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Ocak - fiubat / January - February 2005 Seramik Trkiye 119

ZET

Camn kalitesi dflmeden ok defa geri dnfltrlebilmesineramen geri kazanma uygun olmayan baz cam trleri vardr.Hammaddelerin, enerjinin ve doal kaynaklarn korunmas veevre kirliliindeki azalma iliflkisi asndan, camn gerikazandrlmas ynnde kuvvetli bir destek vardr.

Seramik ise camdan daha nce keflfedilmifltir. Seramik sr teknikolarak camdan baflka bir fley deildir. Bu nedenle, atk camlardanartistik seramik srlar oluflturulmas mmkndr.

Cam tozlarna eflitli eriticilerin ve renklendiricilerin eklenmesi ileuygun kompozisyonlar yaratlmfl; krakle, mat, akc, toplanmalve kristal srlar oluflturulmufltur. Ortaya kan artistik srlar

uygulama olarak eflitli seramik objelere aktarlmfltr. Byleceatk camlar artistik sr olarak dekoratif amalarla gnlk yaflantmzataflnmfltr.

1. GRfi

Seramik ve cam bir btnn paralar gibidir, birbirlerinitamamlarlar. Kimyasal olarak ise cam bir tr seramiktir. Temelolarak ayn hammaddelerden oluflurlar. Teknolojik geliflmeler debu nedenden dolay birbirine paralel olarak ilerlemifltir.

Tarihte insanlar tarafndan camn ilk kez eritilmesi, seramiinkullanmndan ok sonradr. mlekiliin tarihesi yaklaflk M..8. binyl ile 6. binyllara rastlamakta olup, dnyann deiflikblgelerinde birbirlerinden kopuk olarak ayr ayr geliflmifltir. Cam

ise yaklaflk M.. 3. binylda Mezopotamyada keflfedilmifltir. Dahasonra Msrdaki zanaatkrlarn yaptklar kefliflerde; mlekamuruna camn ana maddelerinden biri olan sodann eklenmesiile sr yapmnn temelleri atlmfltr. Yzyllar sren aflamalarsonucu zanaatkrlar; camn ve seramiin kimyasn birlefltirerekSeramik Sr Konseptini ni oluflturmufllardr. Gnmzde iseseramik ve cam teknolojileri gemifle oranla ok fazla geliflmifltir.Deiflmeyen tek fley ise camn ve seramiin hammaddeleridir.Seramik srlarnda ise pek ok aflamalar kaydedilmifl, birok yenitr yaratlmfltr.

Camn artistik seramik sr olarak kullanlabilmesinin nedeni ise,camn seramiin temelini oluflturmasdr. Cam, doas gereiseramik srdr. Buradan karak artistik srlara ulaflmak ama

edinilmifltir. Bu sayede ok farkl artistik srlarn oluflturulmasmmkn olabilmektedir.

Atk camlar ileartistik seramiksrlarnn retilmesiProducing artistic glazesfrom cullet

ABSTRACT

Although glass can be recycled infinitely without loss of quality,there are some glass products that are not suitable for recycling,mainly based on the conservation of raw materials and energy,and the associated reduction in pollution.

Ceramic has been found before the discovery of glass. Glaze istechnically nothing but glass. For this reason it is possible to formglaze from crushed glass, called Cullet.

Corresponding compositions are created by adding stiffeners (suchas clay and fluxes), melting agents (such as lead or soda) andcoloring oxides to cullet; cracle, matte, crawling and cristalineglazes are made. Artistic glazes which show up are carried to

various ceramic objects. Thus these cullets have come into ourdaily life as artistic glazes which are used for decorative purposes.

1. INTRODUCTION

Ceramic and glass are like pieces of a whole, they completeeachother. In terms of chemistry, glass is a kind of ceramic. Basicly,they are made of the same raw material. For this reasontechnological development has been paralel in both areas.

Historically, melting of the glass by mankind, for the first time, hasbeen far later than the use of ceramics. Pottery which has a historythat meets years BC 8000-6000, has developed separately in thedifferent parts of the world apart from each other. Glass, on theother hand has been discovered in Mezopotamia approximately

in year 3000 BC. Later, through the discoveries made by thecraftsman in Egypt, the foundations of glaze-making have beenlaid by adding soda to clay, which is one of the basic materials ofglass. After going through many phases through years , craftsmanhave set the Concept of ceramic glaze by combining the glasschemistry and ceramics.

Today, ceramic and glass technologies have improved a lot whencompared with the past. The only thing that remains unchangedis the raw material of glass and ceramic. Ceramic glazes havegone through many phases and many types have been created.

The reason why glass can be used as artistic ceramic glaze is thatglass is the basis of ceramic. Glass, by nature is glaze. Taking

this into consideration, it was aimed to acquire artistic glazes; anddue to that, forming different artistic glazes may be possible. Usingglass is considered as an adventage in making artistic glaze. Glass

Marmara niversitesi Gzel Sanatlar Fakltesi,Seramik - Cam Blm, stanbul

Prof.Dr.AteflArcasoy

Marmara University Faculty of Fine Arts,Ceramics - Glass Department, stanbul

Selen AtakDilaver

Science - TechnologyBilim - Teknoloji


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Ocak - fiubat / January - February 2005 SeramikTrkiye120

Artistik seramik sr yapmnda camn kullanm avantaj olarakkabul edilmelidir. Bunun nedenleri; cam kullanmnn ekonomikolmas, hammaddeye kolay ulafllabilinmesi, pratik olmas, zgnsrlarn ortaya kabilmesidir.

Ancak artistik seramik srlarnn oluflturulmasnda baz snrlarvardr. Cam tozu kullanarak seramik sr oluflturulmas, normalsr oluflumundan teknik olarak farkldr. Normal srlar Segeryntemi kullanlarak hazrlanrken, cam tozu kullanlarak eldeedilen srlarda bu ynteme ihtiya duyulmaz. Cam tozlarna belirlieriticilerin, hammaddelerin ve renklendiricilerin eklenmesi yeterliolabilmektedir. Bunun yannda cam tozu kullanarak tm artistiksrlar da elde edilemez. Yine de bu yntemler ile elde edilen srlar,gnlk yaflamda dekoratif amalar iin kullanlmaya msaittirler.

Geliflen teknoloji iinde atk camlarn kullanm gerek sanatsalgerekse endstriyel olarak gn getike artmaktadr. Bu alflmadaatk camlardan sadece artistik seramik sr oluflturulmasamalanmfltr.

2. ATIK CAMLAR / GER DNfiM

2.1. Camn Kullanm

Camn birok kullanm yeri vardr ve bunlardan en popler, orijinalolan ise ambalajdr. Camn temel zellikleri onu son derece istekuyandran bir madde klar. Hijyeniktir, ntrdr ve iinde saklanabilenieriin karakteristiklerini deifltirmez. Saydam cam iindekilerigrnr klarak tketicilerde daha ok alm istei uyandrr. eriinkorunmas iin renklendirilebilinir ve ieriin gzle grlebilmesirnn satfl iin nemli bir etkendir.

Camlar genellikle renklerine gre snflandrlrlar: Saydam camlar

(kavanozlarn ou), yeflil camlar (flarap flifleleri) ve kahverengicamlar (bira flifleleri).

Kirlenme camn geri kazandrlmasn engeller. Geri dnflmyaplacak cama yanlfl trde bir maddenin karflmas sonutakacak btn geri dnflml camlarn atlmasna neden olur.rnein sadece 25 gr.lk seramik paras btn bir tonluk camnkirlenmesine neden olur. Geri dnflm yaplacak camlarnsadece bu amala toplanmas gerekir. Geri dnflm yaplacakcamlarla ilgili nemli bir kural; iinden bakldnda dflarsgrlemeyen (saydam olmayan) cam geri dnflm iin uygundeildir. Eer cam flpheli ise dier camlar riske sokmamak iinbunun geri dnflm dflnda tutulmas gerekir. Ayrca btnkapaklarn, azlarn ve tpalarn karlmas gerekir. Bu maddelergenellikle elik veya plastikten oluflur, bunlar da aralarnda geri

dnfltrlerek kullanma kazandrlabilirler.

2.2. Hangi Camlar Geri Kazandrlabilir?

Camn kalitesi dflmeden ok defa geri dnfltrlebilmesineramen geri kazanma uygun olmayan baz cam trleri de vardr.Bunlar geri kazandrlacak camda kirlenmeye neden olacak armetal oksitler ieren rnlerdir ve bunlar sonunda rnde kusurlaroluflturarak kalitenin dflmesine neden olurlar.

Geri kazandrlabilen camlar Btn saydam, yeflil, kahverengi flifleler Alkolsz iecek, maden suyu, flarap ve bira flifleleri Btn cam kavanozlar

using is economical, practical, that it is easy to reach the materialand so that original glazes may be formed.

Nevertheless, there are some boundaries of forming glazes.

Technically, forming glazes by using cullet differs from ordinaryglaze forming. The Seger technique is used to prepare ordinaryglaze, while this technique is not needed to prepare glaze obtainedfrom cullet. Adding specific fluxes, raw materials and coloringoxides to cullet, may be sufficient. Besides, all artistic glazes cannot be obtained by using cullet. Still, glazes that are preparedbythis procedure are available for daily decorative purposes.

The use of glass both artistically and industrially is improving dayby day through technical development. Within this work, formingartistic glaze from waste glass is aimed.

2. RECYCLING

2.1. The Use of Glass

Glass has many uses, an done of the most popular and original ispackaging. The unique properties of glass make it a highly desirablematerial. It is hygienic, neutral and does not change thecharacteristics of the content stored in it. Clear glass makes thecontents visible and attractive to consumers. It can also be tintedto protect the contents and supply eye-cathcing ability as well,which is important factor in marketing the product.

Glass is generally classified according to its colour; clear (mostglass jars), gren(wine bottles) and brown/amber (beer bottles)

Contamination prevents glass from being recycled. Putting in thewrong type of material together with recyclable glass will caused

the whole lot to be rejected. For example, just 25 g of ceramic cancontaminate a whole tonne of glass. This then has to go to landfill,as the contaminants cannot be efficiently separated out. Be surethat only recyclable glass is collected for recycling. A simple ruleof thumb is that any thing that you cannot see through, when heldagainst the light is not suitable for recycling. If doubtfull, its beterto leave them out of recycling bin than risk contaminating thewhole lot. Also remember to remove all caps and lids. These aregenerally steel or plastic and be recycled separately.

2.2. What Types of Glass Can and Cannot be Recycled?

Although glass can be recycled infinitely without loss of quality,there are some glass products that are not suitable for recycling.They contain heavy metal oxides that can contaminate recycled

glass and result in imperfection and poor quality of the product.

Glass sutable for recyclingAll clear, gren and amber glass bottles.Soft drink, mineral water, wine, beer.All glass jars.

Glass not suitable for recyclingBroken window glass.Broken wind screends.Heat treated glass e.g. Corning Ware.Pyrex, vision ware, ceramics, vases, china.TV tubes.White opaque bottles.Labotary bulbs& fluorescent tubes.Mirrors.



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Geri kazandrlamayan camlar Krk pencere camlar Otomotivde kullanlan n cam krklar Pyrex, gzlk camlar, seramikler, vazolar, porselen rnler Is uygulanmfl camlar; arkorok kaplar TV tpleri Beyaz opak flifleler Tbbi ve laboratuvar camlar Ampuller ve fluoresan tpleri Cam elyaflar (fiber cam) Aynalar

2.3. Camn Geri Dnflmnn Yararlar

tlmfl cam kullanm doal kaynaklar kurtarr. Geri kazandrlan camlar, harmanlanmfl hammaddelerdenyaplan camlardan daha dflk scaklklarda ifllemden geirilir. Geri dnfltrlen cam hava kirliliini % 20 ve su kirliliini %50orannda azaltr.

Kat atn miktar azalr.

Trkiyede, geri dnflmde ilk adm 1970lerin baflnda fiiflecamtarafndan atlmfltr. fiiflecam, 2000 yl sonuna kadar 1 milyon toncam ambalaj atn retime katarak yeniden flifle/kavanoz halinegetirmifltir. Adet olarak 2 milyarn zerinde cam ambalaj ile ifadeedilebilen bu deer doal kaynaklardan 45 trilyon TL deerinde25 bin ton fosil yakt ve 1,2 milyon ton hammadde tasarrufusalamfltr. Her yl ortalama 6570 bin ton atk cam ifllenerek,%36 lk cam kazanm oranna ulafllmfltr.

3. UYGULAMALAR

3.1 Cam Tozlarnn Elde Edilmesi

Uygulamalarda kullanlacak en nemli hammadde olan camtozunu, gnlk kullandmz birok cam objenin ezilerek tlmesiile elde edebiliriz. Bu hammaddenin salanmasnda yaflamortamlarmz biriktirilen flifleler ve kavanozlar bile yeterliolabilmektedir.

fiifleler ve kavanozlar renklerine gre ayrlp, snflandrlrlar.zerlerindeki yabanc maddeler; ktlar, kapaklar vs. titiz birflekilde kartlr. Daha sonra camlar kendi gruplar iinde krlp,ince bir toz haline gelene kadar ezilirler. Bu tozlar bir elektengeirilerek aralarndaki iri cam paralarndan arndrlrlar (Resim1).

Renksiz saydam camdan elde edilen cam tozunun, sadece ezilmekyerine, sr yapmnda kolaylk salanmas ve srn geliflmesinde

tane byklnn salayaca dezavantajlar yznden,tlmesinde yarar vardr. Ancak renkli camlardan elde edilecekcam tozlar iin ayn yntem geerli olmamaktadr. Renkli camlartlerek cam tozu haline getirildiklerinde; frnlama ifllemindensonra camlarn kendi renginden elde edilmek istenen renkkaybolmaktadr. Bunun iin renkli camlar tlmeden ezilmelidir.

3.2. Cam Tozlar Kullanlarak Artistik Seramik Srlarnn EldeEdilmesi

Artistik sr ad altnda toplanan srlar, endstriyel retimde azkullanlan veya hi kullanlmayan, buna karfln, endstriyel yntemlerile retilen paralar da kapsamak zere, kullanld her rnesanatsal deer katan srlardr.

Artistik srlarn tanmlanmasnda n planda gelen iki belirgin zellik,artistik srlarn doku ve renk zellikleridir.

2.3. Views on the Benefits of Glass Recycling

Using cullet saves the natural resources. Recycled glass can be processed at a lower temperature thanblending glass from raw materials. Recycling glass reduces related air pollution by 20 % and thewater pollution 50 %. The quantity of solid waste is reduced.

In Turkey, recycling started in early 70s, by fiiflecam. fiiflecam hasused 1 million tons of waste glass and recycled into bottles and

jars, up till the end of year 2000. By this way, we can say that; thevalue over 2 billion pieces of waste glass which 45 trillion TL. ofnatural resources; 25 thousand of fossil fuels and 1,2 million tonraw material was saved. Every year, approximately 65-70 thousandtons of waste glass has been processed and reached 36 % gainedglass.

3. APPLICATION

3.1. Obtaining Cullet

Cullet which is a primary raw material that will be used in theapplications can be obtained by grinding glass that are used daily.In providing this raw material even bottles and jars collected in ourenviroment can be sufficient.

Bottles and jars are classified according to their colour. Forreignmaterials on them like caps and lids are removed carefully.Afterwards, glass are broken into pieces in their own groups tillthey turn into dust.Then the dust is sifted and the remaining bigglasses are removed.

The ground cullet obtained from transparent glass is moreadventageous than crushed one, only in order to have support inglaze making and to avoid the dis advantages, that the big pieceswill cause. However, the same method wont be valid for culletthat will be obtained from coloured glass. When coloured glassare ground into cullet, the colour which is aimed to obtain fromthe own colour of the glass dissapears after the firing process. Forthis reason coloured glass should be crushed without grinding.

3.2. Obtaining Artistic Glaze by Using Cullet

Glazes that is tittled under artistic glaze wheather used minorlyin industrial production or not used at all, comprising all piecesproduced by industrial techniques adds an artistic value to allproducts they are used in.

Resim 1 / Picture 1



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rnein bir saydam porselen srnda veya rtc bir akini srndailk aranan zellik; hataszlk ve standartlk, ayn renk, doku vegrnt zelliidir.

Artistik srlarda ise renk ve zellikle doku elde etmede,rastlantlardan srn bir zellii gibi yararlanlr.

3.2.1. Doal Krakle Srlar

Krakle sr szc ile seramik srlarnda; yzeyi belirgin bir atlaka ile kaplanmfl srlar tanmlanr.

The two major features that are outstanding in defining artisticglaze are the tissue and colour features of the artistic glaze. Forexample, in a transparent china glaze or opaque stoneware glaze,the first major feature is perfection and standartization; even colour,tissue and appereance.

However, in obtaining colour and especially tissue in artistic glaze,coincidences are taken adventage of just like a caracteristic of theglaze.

1 a

1 b

1c

1d

1e

10 ksm/part cam tozu/cullet





1 ksm/part kaolin/clay





5 ksm/part kalsine/calc. soda





3 ksm/part ZnO

3 ksm/part ZnO

3 ksm/part ZnO

3 ksm/part ZnO

3 ksm/part ZnO

0,57 ksm/part FeO

0,57 ksm/part CuO

0,57 ksm/part CoO

0,57 ksm/part Cr2O3

0,57 ksm/part MnO2

1a da FeO oran az olduu iin sr ak sar renktedir. 1b de iseCuO oran sr iin yeterlidir. 1c ve 1dde CoO ve Cr2O3in boyayczelliklerinin yksek olmas nedeni ile srlar saydamlklarnkaybetmeden, maksimum oranda renklenmifltir. Ancak 1edeMnO2in hacimsel genleflme etkisinden dolay sr kprmfltr(Resim 2).

3.2.2. Mat Srlar

Seramik rnn yzeyi gelen fl yanstmayacak flekilde mat birtabaka ile kapl olan srlar, mat srlar olarak tanmlanrlar. Budeney grubunda ise temel artistik mat sr, izelgede grlenmiktarlarda metal oksitler kullanlarak renklendirilmifltir.

Mat srn renklendirilmesinde, oksit orannn azl veya okluusrn kalitesini etkilemez. 2ada srn kaln srld yerler sar,ince srld yerler ise kahverengidir. 2ede ise MnO2in hacimselgenleflme etkisi nedeni ile sr kprmfltr(Resim 4), (Resim 6).

1a 1b 1c

1e1d

2a 2b 2c

2e2d

Resim 2 / Picture 2

3.2.1. Natural Cracle Glaze

In glazes, the word cracle glaze defines glaze that has a surfaceplainly covered by a net of cracks.



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3.2.3. Akc Srlar

Yaplar gerei, piflme srasnda normalden fazla akan, artistiksrlardr. Genellikle mat veya az akflkan parlak srlarn zerinesrlerek kullanlan akc srlar, piflme srasnda alttaki sr ilebirlikte artistik dokular olufltururlar. Bu deney grubunda (srn

akflkanlk etkisini daha iyi gzlemleyebilmek iin;) biskvi plakannzerine, renksiz mat sr uygulanmfltr. Akflkan sr ise 2.kat olaraksadece plakann st yarsna srlmfltr. Deneme plakalar frnda,yzey ile 60 lik a yapacak flekilde yerlefltirilip, frnlanmfllardr.

In 1a, the glaze is in light yellow caused by small proportion of FeO.However in 1b, the proportion of CuO is sufficient fort he glaze. In1c and 1d, the glazes are coloured maximum without loosingtranparency due to their high dying quality. Whereas in 1e, theglaze is rised because of the volume expansion effect of MnO2(Picture 2).

2 a

2 b

2c

2d

2e











1.25 ksm/part K feldspat/felspar





1.25 ksm/part Na feldspat/felspar





0.4 ksm/part FeO

0.4 ksm/part CuO

0.4 ksm/part CoO

0.4 ksm/part Cr2O3

0.4 ksm/part MnO2

3a 3b 3c

3e3d

3ada FeO orannn az olmas nedeni ile sr; ak sar renktedir.3bdeki srn transparantl yeterlidir. 3cde CoO sr koyu bir rengeboyamfltr. 3dde ise Cr2O3in bir zellii olarak, oksit soda ilekullanldnda srda ayrflmalar oluflabilmektedir. 3ede MnO2inhacimsel genleflme etkileri srda gzlenmektedir. Srlar, mat sr

zerine uygulandklar iin akclk etkileri dengelenmifltir (Resim5).

Resim 3 / Picture 3

Mat sr/ Matte GlazeMat sr/ Matte Glaze

10 ksm/part cam tozu/cullet10 ksm/part cam tozu/cullet

1 ksm/part kaolin/clay1 ksm/part kaolin/clay

1.25 ksm/part K feldspat/felspar1.25 ksm/part K feldspat/felspar

1.25 ksm/part Na feldspat/felspar1.25 ksm/part Na feldspat/felspar

3 a

3 b

3c

3d

3e
















0.54 ksm/part FeO

0.54 ksm/part CuO

0.54 ksm/part CoO

0.54 ksm/part Cr2O3

0.54 ksm/part MnO2



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Ekim - Aralk / October - December 2004 SeramikTrkiye124

3.2.4. Toplanmal Srlar

Piflme srasnda damarlar ve adacklar fleklinde toplanarak yzeydeartistik dokular oluflturan srlardr. Bu gruptaki srlar ilgili izelgedegrlen miktarlarda metal oksit katklar ile renklendirilmifllerdir.Srlar plakalara aflr kaln miktarlarda srlmfllerdir.

3.2.2. Matte Glaze

Glaze that are covered with a matte layerfor the ceramic not to reflect the light,is defined as Matte Glaze. In thisexperiment group, the essential artisticmatte glaze is coloured by using theamounts of metal oxide shown on therelevant table.

In colouring matte glaze, the quality ofthe glaze is not a effected by theproportion of the oxide. In 2a the partsthat the glaze is applied in thick layersare yellow, whereas the parts that isapplied in thin layers are in Brown. In 2eglaze is rised because of the volumeexpansion of MnO2 (Picture 4),(Picture 6).

4a 4b 4c

4e4d

Resim 4 / Picture 4

4 a

4 b

4 c

4 d

4 e




10 ksm /part cam tozu/cullet

10 ksm /part cam tozu/cullet






2.5 ksm/part PbO4

2.5 ksm/part PbO4

2.5 ksm/part PbO4

2.5 ksm/part PbO4

2.5 ksm/part PbO4

5 ksm/part MgO

5 ksm/part MgO

5 ksm/part MgO

5 ksm/part MgO

5 ksm/part MgO

0.55 ksm/part FeO

0.55 ksm/part CuO

0.55 ksm/part CoO

0.55 ksm/part Cr2O3

0.55 ksm/part MnO2

Resim 5 / Picture 5

Resim 6 / Picture 6

3.2.3. Flowing Glazes

These are the artistic glazes that are more flowing during firingdue to their structures. Flowing glazes which are usually used byapplying less flowing bright glazes form artistic tissues togetherwith the glaze underneath during the firing process. In thisexperiment group (in order to observe the flowing effect of theglaze) transparent matte glaze is applied over the biscuit plaque.Flowing glaze on the other hand is applied as a second layer onthe top of the plaque. The experimental plaques are placed tomake an angle of 60 in the kiln and fired.

In 3a the glaze is light yellow because of the small proportion ofFeO. The transparency of the glaze in 3b is sufficient. In 3c CoOhas dyed the glaze into a darker colour. In 3d, when Cr2O3 istogether with a soda, there may be decomposition in the glazecaused by the characteristic of Cr2O3 . In 3e the volume expansioneffect of MnO2 is observed in the glaze. the flowing effect balanced,as the glazes are applied over the matte glaze (Picture 5).

3.2.4. Crawling Glaze

These are glazes that form artistic tissues over the surface gatheringlike veins and insulas during firing. Glazes in this group are dyedwith metal oxide additions in amounts shown on the table. Theglaze is applied in excessive amounts over the plaques.



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4bde CuOin slyen ile beraber kullanm nedeni ile sr turkuvazyerine yeflile kayan bir renk alr. 4cde CoO ile olduka dzgnkabarklklar elde edilirken, 4dde ise Cr2O3 in verdii bir zellikolarak bunlar yuvarlak hatldr. 4ede ise MnO2in verdii hacimselgenleflme etkisi ile srda kprmeler oluflmufltur (Resim 3).

4. SONU

21. yzyla girildiinde, cam retiminde kullanlan enerji miktar% 25 orannda azalmfltr. Bu dflflte rol oynayan nemli etkenler;gncel yaktlarn kullanlmas, gelifltirilmifl frn tasarmlar, eritmeteknikleri ve geri dnfltrlen cam kullanmnn artmas ile ilgilidir.nk camn en nemli zellii % 100 orannda, ypranmadan vekalitesinde bir dflfl olmadan, defalarca geri dnfltrlebilmesidir.

Geri dnfltrlerek elde edilen atk camlardan artk yeni projelergereklefltirmek gerekmektedir. Bu balamda artistik seramiksrlarnn yapmnda atk camlarn kullanm avantaj olarak kabuledilmelidir. Bunun nedenleri; ekonomik ve pratik olmas, atlye

ortamlarnda kolay elde edilebilmesi, enerjinin ve doal kaynaklarnkorunmas ve evre kirliliindeki azalma iliflkileridir.

Seramik srlarnda kullanlan eriticilerin yerlerinin atk camlar ileyer deifltirmesi sonucu, seramik srlarnn birim maliyetleri degiderek dflmektedir. Atk camlar ile dflk scaklklarda rahatlklagelifltirilebilecek artistik srlardan baflka, raku srlar da arafltrlabilir.ndirgen frn ortamlarnda sr arafltrmalar yaplabilir, lsterli srkompozisyonlar oluflturulabilir.

In 4b, due to the use of CuO with PbO4 the the glaze is closer togreen than turquoise. In 4c regular blisters are obtained whereassmooth, in 4d these are round shaped caused by the characteristicsof Cr2O3. In 4e the glaze is rised again due to the volume expansioneffect of MnO2 ( Picture 3).

4. CONCLUSION

Over the years the amount of energy used to manufacture glass,has reduced by more than 25%. The significant reduction in energyuse is due to the use of natural gas as the dominant energy,improved furnace design and melting techniques, and the increaseduse of cullet. The amazing thing about glass is that it is 100 %recyclable. It does not wear out and can be recycled over and overagain without any reduction in quality.

New projects should be raised upon waste glass that is acquiredthrough recycling. In that aspect, using waste glass in makingartistic glaze should be considered as an adventage. The reasons

for that are that they are economical, practical, are easily acquiredin workshops and that the energy and natural sources are protectedand the correlations in decreasing pollution.

The removal of melters used in ceramic glazes with cullets, hasbrought about a gradual degrease in unit costs of ceramic glaze.apart from artistic glaze that can easily be developed in lowtemperature, raku glazes can also be researched. In reduced kilnenvironment glaze research may be, and lusterware glazecompositions can be formed.

Kaynaka / References

1- ARCASOY, Atefl, Seramik Teknolojisi, stanbul, Marmaraniversitesi Gzel Sanatlar Fakltesi- Seramik Anasanat DalYaynlar No:1, 1983

2- ATAK, Selen, Atk Camlar ile Artistik Seramik Srlarnnretilmesi, Yksek Lisans Tezi, M..Gzel Sanatlar Enstits,2004, stanbul

3- Geri Kazanmlar ve Cam Kumbaralar, evre, Eriflim:20.03.2004, [www document], URL,www.anadolucam.com.tr/cevre/cevre.html

4- Glass, Eriflim:11.11.2002, [www document], URL,www.wastecom.sa.gov.au/wmc/FactSheets/glass.html

Resimler / Pictures

tlmfl renksiz camKrakle sr uygulamas. 1000CKrakle ve toplanmal sr uygulamas Krakle sr: 1000CToplanmal sr: 1200 CMat ve akc sr uygulamas. 1000CAkc sr uygulamas. 1000CMat sr uygulamas. 1200C

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02

03

04

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ZET

Ferrit olarak adlandrlan manyetik seramik malzemeler ilave birmetalik iyon ieren demir oksitli bilefliklerdir. Genellikle ferritler,yumuflak ve sert ferritler olmak zere iki gruba ayrlrlar. Bualflmayla, iyi demanyetizasyon direnlerinin yan sra, maliyetleride dflk olan stronsiyum ferrit kalc seramik mknatslarn retimiincelenmifltir. Demir oksit (Fe2O3) kayna olarak hematit (~%99,97 Fe2O3), stronsiyum oksit (SrO) iin stronsiyum karbonat(SrCO3) ve tane bymesi kontrol iin silika (~% 99 SiO2)kullanlmfltr. Stokiyometrik olmayan SrO.4Fe2O3, SrO.5Fe2O3,SrO.5,5Fe2O3ve stokiyometrik SrO.6Fe2O3 bilefliklerinin karflmlarhazrlanmfl ve karfltrma, tme, kalsinasyon, flekillendirme,balayc uzaklafltrma, sinterleme ve manyetizasyon ifllemleriuygulanmfltr. Kalsinasyon 1000, 1100 ve 1200 Cde 4 saat olarak

yaplmfltr. Kalsine edilen tozlarda oluflan fazlar X-flnlar krnmcihaz (XRD) ile belirlenmifltir. Btn numuneler ayn scaklkta verejimde sinterlenmifllerdir. Daha sonra yzey dzgnlkleri salanp,manyetizr yardm ile manyetik hale getirilmifllerdir. Elde edilenson rn olan stronsiyum hekzaferrit seramik mknatslarnyounluklar ve manyetik zellikleri tespit edilmifltir.

Anahtar Kelimeler : Manyetik seramikler, ferrit, stronsiyumhekzaferrit retimi, manyetik zellikler.

1. GRfi

Ferritlerin yapsnda demir oksit (Fe2O3) ve eflitli ilave metaliyonlar bulunur. Fe2O3 ile birleflen iyonlar kristal yapy ve ferritintipini belirler. Yumuflak ferrritler manyetik alandan karldktansonra manyetik zelliklerini yavafl yavafl kaybetmeye bafllarlar yanigeici manyetiklik sergilerler. Yumuflak feritlerin ou ters spinelyapsnda olup, MO.Fe2O3 veya MFe2O4 genel bileflimine sahiptirler.M iki deerlikli metal iyonunu, (Fe+2, Mn+2, Ni+2 veya Zn+2)gstermektedir. Yumuflak ferritler dakikada bir ok kezmanyetizasyon ve demanyetizasyon edilebildikleri iin, alternatifakm g ve yksek frekans ifllemleri gerektiren uygulamalar iintercih edilirler. En nemli kullanm alanlarndan bazlar dflksinyalli hafza ekirdei, ses ve grnt cihazlar ve kayt kafalardr.Sert ferritler srekli manyetik zellik gsterirler ve bunu yitirmezler.Kalc mknats olarak kullanlan sert ferritlerin ou hekzagonalkristal yapsnda olup MFe12O19veya MO.6Fe2O3kimyasal bilefliminesahiptirler. Bileflimdeki M yerine Ba, Sr veya Pb gelebilir. Bugruptaki en nemli ferrit, 1952de Ferroxdure ticari adyla Philips

Company tarafndan piyasaya srlen baryum hekzaferrittir(BaO.6Fe2O3). Yakn zamanda baryum hekzaferritlerin yerine dahaiyi manyetik zelliklere sahip stronsiyum hekzaferrit (SrO.6Fe2O3)

Stronsiyum hekzaferritseramik mknatsretimiProduction of strontium hexaferriteceramic magnet

ABSTRACT

Magnetic ceramics classified, as ferrites are iron oxide compoundsthat contain an additional metallic ion. Ferrites are commonlydivided into two groups such as soft and hard ferrites. In this study,the production of strontium hexaferrite ceramic permanent magnetswas investigated because of their low cost besides good resistanceto demagnetisation. Hematite (Fe2O3with ~% 99,97 purity), strontiumcarbonate (SrCO3) as SrO source and silica (SiO2 ~% 99 purity) asa grain growth-controlling agent were used for the experimentalwork. Stoichiometric compound of SrO.6Fe2O3 and a series ofnon-stoichiometric compounds SrO.4Fe2O3 , SrO.5Fe2O3 ,SrO.5.5Fe2O3 were prepared by using classical ceramic processingroute. Calcination was done at 1000, 1100 and 1200 C for 4 hours.Phases in the calcined powders were determined by X-ray

diffractometer (XRD). All samples were sintered obeying the samethermal regimes. After surface preparation for smoothness, thesamples were magnetized by using magnetizer. The densities andmagnetic properties of the final products were investigated byusing the relevant techniques.

Key Words: Magnetic ceramics, Ferrite, Production of strontiumhexaferrite, Magnetic properties.

1. INTRODUCTION

Iron oxide (Fe2O3) and various additional metallic ions are presentin the structure of ferrites. Ions combining with Fe2O3 determine

the crystal structure and ferrite type. Soft ferrites are going to loosetheir magnetic properties slowly after removing them from magneticfield. In other words, they exhibit temporary magnetization. Mostsoft ferrites have inverse spinel structure and have the generalcomposition MO.Fe2O3 or MFe2O4, where M is a divalent metal ionsuch as Fe+2, Mn+2, Ni+2 veya Zn+2. Soft ferrites are the obviouschoice for applications requiring ac power and high frequencyoperation since they must be magnetized and demagnetised manytimes per second. Some of the most important uses for soft ferritesare low-signal levels, memory-core, audiovisual, and recording-head applications. Hard ferrites show permanent magneticbehaviour. Most of the hard ferrites, which are used for permanentmagnets, have the general chemical formula of MFe112O19 orMO.6Fe2O3 and these are hexagonal in crystal structure. The mostimportant ferrite of this group is barium hexaferrite (BaO.6Fe2O3),

which was introduced by the Philips Company in 1952 under thetrade name Ferroxdure. In recent years, the barium hexaferriteshave been replaced to some extent by the strontium hexaferrites

Anadolu niversitesi, Malzeme Bilimi ve Mhendislii Blm,ki Eyll Kampus, Eskiflehir

Prof.Dr.NuranAyArafl. Gr.H. BoaPoyraz

Anadolu University, Department of Materials Science and Engineering,Iki Eylul Campus, Eskisehir

Prof.Dr.NuranAyResearch Assist.H. BoaPoyraz


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kullanlmaya bafllanmfltr. Sert ferrit seramik kalc mknatslardflk maliyetlerinden dolay elektrik motorlarnda, jeneratrlerde,rlelerde ve motorlarda genifl bir uygulama alan bulur. Elektrikuygulamalarna rnek olarak hoparlr mknatslar, telefon zilleri

ve alclar gsterilebilir. Bunlar ayn zamanda kap kapamatutalarnda, contalarnda ve mandallarnda ve eflitli oyuncaklardakullanlrlar. [1-5]. fiekil 1de stronsiyum hekzaferritin (SrFe12O19veya SrO.6Fe2O3) kristal yaps gsterilmektedir [6].

(SrO.6Fe2O3), which have superior magnetic properties comparedwith the barium hexaferrites. Hard ferrite ceramic permanentmagnets find widespread use in electrical motors, generators,relays and motors. Electronic applications include magnets for

loudspeakers, telephone ringers and receivers. They are also usedfor holding devices for door closers, seals, and latches and in manytoy designs [1-5]. Crystal structure of strontium hexaferrite isshown in Figure 1 [6].

Ceramic magnets consist of chemically combined mixtures ofmetallic oxides that produce a dense, homogeneous, crystallinestructure possessing the important property of high resistivity [7].The raw materials for making ferrite magnets are normally ironoxide and carbonates of Ba or Sr. The magnetic properties offerrites are largely dependent on the processing routes of thesynthesized powders [7]. There have been many studies on therelated subjects. Traditionally, strontium hexaferrite powders aresynthesized by a mixed oxide ceramic method, which involves thesolid-state reaction between SrCO3 and Fe2O3 at a high calcination

temperature (~1200 C) [8]. Besides this, to prepare ultra-fineSrFe12O19 powder low temperature chemical methods such ashydrothermal [9-10], salt-melt [11], co-precipitation [12-15], sol-gel [16] and sonochemical [17] have been also employed. Ceramicmagnets are produced by mixing Fe2O3 with BaO, BaCO3 or Srcompounds followed by calcination at 1000-1200 C and shapingand sintering at 1200-1300 C [18]. In general, better magneticproperties are obtained when the calcination temperature is inbetween 1100-1200 C [7]. In the result of a study it was determinedthat grain growth is low and grain structure is fine in the magnets,which were sintered in 1200-1250 C [19]. The samples sinteredat 1250 C had the highest density achieved [19]. With the otherstudy of which the effect of ratio of SrO to Fe2O3 in strontiumhexaferrite on magnetic properties was investigated, the bestmagnetic properties was obtained (with controlled addition of SiO2and CaO) by the optimum Fe2O3/SrO ratio varying from 5.75 to5.85 [20]. Murillo et. al. [21] produced permanent anisotropicmagnets by powder injection moulding under magnetic field inorder to align the magnetic particles. Sintering followed thisprocedure and highly magnetic materials were obtained.In this existing study, strontium hexaferrite ceramic magnets havebeen produced by the result of calcination, sintering andmagnetization processes of stoichiometric and non- stoichiometricmixtures.

2. EXPERIMENTAL STUDIES

In this study, strontium carbonate (Aldrich Chemicals, % 98 SrCO3),hematite (~% 99,97 Fe2O3) provided from Kale Maden and

amorphous silica (SIGMA-Aldrich Chemicals, ~% 99 SiO2) that hasa particle size between 0.5-10 m were used as raw materials.Figure 2 shows the production flow chart of strontium hexaferriteceramic magnets. Fe2O3/SrO molar ratio in the recipe preparedwas determined as 4, 5, 5.5 and 6. 1 wt. % SiO2 was added to eachcomposition in order to prevent grain growth. The samples werecoded as H-4, H-5, H-5.5 and H-6 depending on the Fe2O3/SrOmolar ratios. After mixing in dry medium, raw materials weremilled for 4 hours. Deionised water and Zr balls were used asmilling media. Milled materials were dried in Nve FN 500 dryingoven and then calcinated at 1340 C in Nabertherm N 20/HRfurnace. Calcination process was performed using alumina cruciblesat temperatures 1000 C, 1100 C and 1200 C. Holding time wasdetermined 4 hours and heating rate was 5 C/min. The powder

obtained at the end of the calcinations process was milled for 4hours in a medium containing Zr balls and deionised water.

fiekil 1: Stronsiyum hekzaferritin (SrFe12O19) kristal yaps.

Figure 1:The crystal structure of strontium hexaferrite (SrFe12O19).

Seramik mknatslar nemli bir zellik olan yksek elektrikseldirencin salanmas iin youn, homojen ve kristalin yapda metaloksitlerin kimyasal olarak balanmasyla elde edilmektedirler [7].Normalde seramik mknats yapmnda hammadde olarak demiroksit ve Ba, Sr gibi karbonatlar kullanlr. Ferritlerin manyetikzellikleri ounlukla sentezlenen tozlarn retim yntemlerinebaldr [7]. lgili konularda pek ok alflma mevcuttur. Stronsiyumhekzaferrit tozlar geleneksel olarak, SrCO3 ve Fe2O3n yksekkalsinasyon scaklklarnda (~1200 C) kat-hal reaksiyonu sonucuelde edilirler [8]. Bunun dflnda ultra-ince SrFe12O19 tozuhazrlamak iin hidrotermal [9-10], tuz-ergitme (salt-melt) [11],birlikte-ktrme [12-15], sol-jel [16] ve sonokimyasal [17] gibi

dflk scaklk kimyasal yntemleri de kullanlmaktadr. Seramikmknatslar genelde BaO veya BaCO3 veya Sr bilefliklerinin Fe2O3ile karfltrlmas ve bu tozlarn 1000-1200 C arasnda kalsinasyonifllemi yapldktan sonra flekillendirilip 1200-1300 oC sinterlenmesiyleretilirler [18]. Genelde kalsinasyon scakl 1100-1200 C arasndaiken daha iyi manyetik zellikler elde edilmektedir [7]. Yaplan biralflma sonucunda 1200-1250 Cde sinterlenen mknatslardatane bymesinin dflk ve tane yapsnn ok dzgn olduubelirlenmifltir [19]. En yksek younlua ise 1250 Cde sinterlenmiflnumunelerde ulafllmfltr [19]. Stronsiyum hekzaferritte Fe2O3/SrOorannn manyetik zelliklere etkisinin incelendii bir baflkaalflmayla en iyi manyetik zelliklerin (kontroll SiO2 ve CaOilaveleri ile) optimum orann 5,75-5,85 olmas sonucu ortaya ktbelirlenmifltir [20]. Murillo ve arkadafllar [21] manyetik partikllerinhizalanmas amacyla manyetik alan altnda toz enjeksiyon kalplama

sonucu sinterleme yapp anizotropik Sr-ferrit kalc mknatslarnretmifl ve yksek manyetik zelliklere sahip malzemeler eldeetmifllerdir.


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Ocak - fiubat / January - February 2005 SeramikTrkiye


H-4 (I)

H-5 (I)H-5,5 (I)

H-6 (I)

H-4 (II)

H-5 (II)

H-5,5 (II)

H-6 (II)

H-4 (III)

H-5 (III)

H-5,5 (III)

H-6 (III)

NumuneSample

Kalsinasyon scakl ( C) Sinterleme scakl ( C) Ynsal (bulk) younluk (gr/cm3) Relatif Br (mV) Kalc manyetizasyon (G : gauss)Calcination temperature ( C) Sintering temperature (C) Bulk density (gr/cm3) Relative Br (mV) Permanent magnetization

1000

10001000

1000

1100

1100

1100

1100

1200

1200

1200

1200

1250

12501250

1250

1250

1250

1250

1250

1250

1250

1250

1250

4,66

4,134,22

4,36

4,77

4,28

4,33

4,50

4,93

4,81

4,71

4,80

4,13

3,773,68

3,52

4,29

4,00

3,79

3,65

3,78

4,49

4,56

4,14

590

538,57525,71

478,57

612,86

571,43

541,43

512,86

540

641,43

651,43

591,43

2-Numunelerde istenilen younlua tam olarak ulafllamamfltr.Daha yksek scaklklarda sinterleme ile veya souk izostatikpresleme (CIP) ile daha yksek younluklara ulafllabilir.

3-Manyetik zellik testi sonucu en iyi kalc manyetizasyonu, 1200Cde kalsine edilmifl H-5 (III) ve H-5,5 (III) numuneleri gstermifltir.

2.Actually it wasnt reached to the desired densities in the samples.Higher densities can be reached with the sintering in hightemperatures or with the cold isostatic pressing (CIP).

3.As a result of magnetic property test, H-5 (III) and H-5.5 (III)samples that have been calcined at 1200 oC showed the bestpermanent magnetization.

130

izelge 1: retilen stronsiyum hekzaferrit seramik mknatslarnn baz zellikleriTable 1: Some properties of produced strontium hexaferrite ceramic magnets.


1- Smith, W. F.,Materials Science and Engineering, 2nd Edition,McGraw-Hill, s: 809-856 (1993).2- Lloyd, A., Applications of Hard and Soft Ferrites, KeyEngineering Materials, Vols. 122-124, s:175-182 (1996).3 - Schneider, S. J.,Ceramics and Glasses (Engineered MaterialsHandbook), Part : Magnetic Ceramics (Ferrites), ASMInternational, 1161-1165 (1991).4- W.D. Kingery,H.K. Bowen, D.R. Uhlmann, Introduction toCeramics, John Wiley and Sons, (1960).5- Levinson, L.M., Electronic Ceramics : Properties, Devicesand Applications, General Electric Company, Marcel Dekker,Inc., New York, (1988).6- Smith, J. & Wijn, H. P. J., Ferrites, Philips ResearchLaboratories, Philips Technical Library, s: 177-184 (1959).7- Valenzuela, R., Magnetic Ceramics, Cambridge UniversityPress, s: 98-120 (1994).

8- Haberey, F., and Kockel, A., The Formation of StrontiumHexaferrite SrFe12O19 from Pure Iron Oxides and StrontiumCarbonate, IEEE Trans. Magn., Mag-12 (1976) 983-985.9- Ataie, A., Haris, I. R., Ponton, C. B., Magnetic Properties ofHydrothermal Synthesized Strontium Hexaferrite as a Functionof Synthesis Conditions, Journal of Materials Science, 30 (1995)1429-1433.10-Wang, J. F., Ponton, C. B., Haris, I. R., A Study of the MagneticProperties of Hydrothermally Synthesized Sr-Hexaferrite withSm Substitution, Journal of Magnetism and Magnetic Materials,234 (2001) 233-240.11-Guo, Z. B., Ding, W. P., Zhong, W., Zhang, J. R., Du, Y. W.,Preparation and Magnetic Properties of SrFe12O19ParticlesPrepared by the Salt-Melt Method, Journal of Magnetism andMagnetic Materials, 175 (1997) 333-336.12- Calleja, A., Tijero, E., Martinez, B., Pinol, S., Sandiumenge,

F., Obradors, X.,Hexaferrite Particles by Co-Precipitation andLyophilization, Journal of Magnetism and Magnetic Materials,196-197 (1999) 293-294.

13 - Ataie, A., Heshmati-Manesh, S.,Synthesis of Ultra-Fine Particlesof Strontium Hexaferrite by a Modified Co-Precipitation Method,Journal of European Ceramic Society, 21 (2001) 1951-1955.14-Chen, D. H., Chen, Y. Y., Synthesis of Strontium FerriteNanoparticles by Co-Precipitation in the Presence of PolyacrylicAcid, Materials Research Bulletin, 37 (2002) 801-810.15-Wang, J. F., Ponton, C. B., Haris, I. R.,Ultrafine SrM Particleswith High Coercivity by Chemical Coprecipitation, Journal ofMagnetism and Magnetic Materials, 242-245 (2002) 1464-1467.16-Martinez Garcia, R., Reguera Ruiz, E., Estevez Rams, E.,Structural Characterization of Low Temperature SynthesizedSrFe12O19, Materials Letters, 50 (2001) 183-187.17-Sivakumar, M., Gedanken, Zhong, W., Du, Y. W., Bhattacharya,D., Yeshurun, Y., Fehner, I.,Nanophase Formation of StrontiumHexaferrite Fine Powder by the Sonochemical Method UsingFe(CO)5, Journal of Magnetism and Magnetic Materials, 268

(2004) 95-104.18-Davis, J. R., Metals Handbook (Desk Edition), ASMInternational, 20.5-20.11, (1999).19-King, H. W., Payzant, E. A., Wallace, J. B., Smith, S. W. and20- Arnold, D. F.,Solid State Phenomena, Vol. 25 & 26 (1992)157-164.21-Choroust, V.,Effect of Silicon and Calcium Oxides onStrontium Ferrite , Pokroky Praskove Metal., Vol 35, No 1 (1997)24-29.22- Murillo, N., Gonzales, J., Guraya, C., Gutierrez, M., Seco, F.J., Structural and Magnetic Properties of Sintered Sr-FerritesFabricated by Powder Injection Molding, Journal of Magnetismand Magnetic Materials, 203 (1999) 165-168.23-Kaczmarek, W. A., Idzikowski, B., Mler, K.-H., XRD andVSM Study of Ball-Milled SrFe12O19Powder, Journal ofMagnetism and Magnetic Materials, 177-181, (1998) 921-922.

24-Seyyed Ebrahimi, S. A.,Optimisation of Hydrogen Treatmentof Strontium Hexaferrite Powder, Key Engineering Materials,Vols. 224-226 (2002) 155-158.


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Feldispatlar, genellikle seramik, porselen ve cam retimendstrisinde ve dier retim kollarnda, rnein aflndrclar,sabunlar, camlar ve emayelerde hammadde olarakkullanlmaktadr. Snrl kaynaklara sahip doal hammaddelerintam olarak ne kadar uzun sre ihtiyalar karfllayacabilinmemektedir. ngiltere ve baz Avrupa lkelerinde feldispatyerine cornish stone ad verilen ksmen kaolonize olmufl potasyum

feldispat ieren malzemeler kullanlmaktadr. Bylesi alflmalar,dnyada rezervi gittike azalan hammaddeler yerine alternatifolanlarnn kullanlmas ynnde hzlanmaktadr. Bu alflmada,deiflik oranlarda farkl tr feldispatlarn yer karosu bnyesine veretilen son rne etkilerinin incelenmesi amalanmfltr. Bu amadorultusunda, pegmatit, nefelin siyenit ve sodyum feldispat ayrayr arlka % 20, 25 ve 30 oranlarnda seilmifl reeteye ilaveedilip toplu klme, su emme, kuru, piflme mukavemetleri veDTA analizleri yaplmfltr. Son olarak her bir ilaveye ait numuneyeHarkort ve otoklav testleri uygulanmfltr.

Anahtar Kelimeler: Feldispat, pegmatit, nefelin siyenit, sodyumfeldispat, piflme mukavemeti.

1. GRfi

Yaplarn i ve dfl yzeylerinin kaplanmas iin seramikhammaddelerden retilen eflitli zellik ve boyutlardaki rnlerekaro seramik ad verilmektedir. Karo seramik endstrisinin nemlirnleri: Fayans, duvar karosu, yer karosu, mozaiktir [1, 2]. Bu trrnlere ait zellikler izelge 1 de verilmifltir.

Yer karosu retiminde, genel olarak; kil, feldispat, kuvars, albit, azmiktarda biskvi kr ve viskozite ayarlayc olarak Na-silikatkullanlr.

Yeryzn oluflturan minerallerin en nemlilerinden biri olanfeldispatlar, bir mineral gurubu olarak yerkabuunun yaklaflk %60 n oluflturmakta ve ou lkelerdeki magmatik, metamorfik

ve sedimanter yataklarda bulunmaktadr. Feldispatlar geneldesusuz alminyum silikatlar olarak tanmlanrlar. Feldispatlar temel gurupta incelenirler [3, 4]:

ABSTRACT

Feldspar has been used as a raw material for ceramic industriesand other fabrication units. It is also used as a raw material insoaps, glasses and enamels. It is not known exactly how long thenatural raw materials that have limited sources are going to meetthe demands. In England and some European countries, insteadof feldspar, partially kaolinized, potassium feldspar containingCornish Stone have been used. In place of raw materials whose

reserves are decreasing day by day in the world, as mentionedabove, some studies concerning this manner are growing. In thisstudy, the investigation on the effects for the additions of differentamounts and types of feldspars in green and final body was aimed.For this purpose, 20, 25 and 30 wt % pegmatite, syenite, andsodium feldspar were added to chosen recipes and total shrinkage,water absorption, dry and fired strength measurements and DTAanalysis were conducted. Finally, Harcourt and autoclave testswere applied to chosen samples.

Key Words: Feldspar, Pegmatite, Syenite, Sodium feldspar, Firedstrength

1. INTRODUCTION

Materials, produced from ceramic raw materials with differentproperties and sizes used to cover inside and outside of buildings,are called as tile ceramics. The important products belonging totile ceramic industry are faince, wall tile, floor tile and mosaic[1-2]. The properties of these materials are listed in Table 1.

For the floor tile production, generally: clay, feldspar, quartz, albite,biscuit fragment (in small amounts) and Na-silicate for alignmentof of viscosity are used as raw materials.

Feldspars, which are the most important minerals forming thecrust of the earth as 60 % are found in magmatic, metamorphicand sedimentary beds. Feldspars are generally described as non-aqueous aluminum silicates. They are usually classified in three

main groups [3-4];

Farkl tr feldispatilavelerininyer karosubnyesine etkilerininincelenmesiThe investigation for the effectsof different feldspar additions

on floor tile body

Anadolu niversitesi, Malzeme Bilimi ve Mhendislii Blm, 26555, EskiflehirArafl. Gr. AliCeylan

Anadolu University, Materials Science and Engineering Dept., 26555, EskiflehirResearch. Assist. AliCeylan

Dumlupnar niversitesi, Seramik Mhendislii Blm, Merkez Kampus, KtahyaArafl. Gr.M. FarukEbeolugil

Dumlupnar University, Ceramic Engineering Dept., Center Campus, KtahyaResearch. Assist.M. FarukEbeolugil

Kale Seramik anakkale Kalebodur Seramik San. A.fi, 17430, an-anakkaleYer Karosu Ar-Ge Gelifltirme YneticisiAliKk

Kale Ceramic, anakkale Kalebodur Ceramic Industry, Share Company 17430, an anakkale

Floor Tile Research. Development Manager AliKk



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fiekil 1: Deiflen oranlardaki pegmatitin toplu klmeye etkisi.Figure 1. The pegmatite effect on total shrinkage.

izelge 7. Nefelin siyenit miktarnn deiflken olduu karflmlarn harkortve otoklav sonular

Table 7. Harcourt and autoclave test results of mixtures with syenite

Testler / Tests

Otoklav / Autoclave

Harkort / Harcourt

Numune 1Sample 1

Olumlu / Positive

Olumlu / Positive

Numune 2Sample 2

Olumlu / Positive

Olumlu / Positive

Numune 3Sample 3

Olumlu / Positive

Olumlu / Positive

izelge 8. Sodyum feldispat miktarnn deiflken olduu karflmlarn harkortve otoklav sonular

Table 8. Harcourt and autoclave test results of mixtures with albite

Testler / Tests

Otoklav / Autoclave

Harkort / Harcourt

Numune 1Sample 1

Olumlu / Positive

Olumlu / Positive

Numune 2Sample 2

Olumlu / Positive

Olumlu / Positive

Numune 3Sample 3

Olumlu / Positive

Olumlu / Positive

fiekil 2: Deiflen oranlardaki nefelin siyenitin toplu klmeye etkisiFigure 2. The syenite effect on total shrinkage.

3. SONULAR VE RDELEME

Killer kurutulduklarnda, flekillendirme suyunun kilden uzaklaflmas

sonucu klme sergilerler. Kil taneleri arasnda yer alan su kildenuzaklafltka taneler birbirine yaklaflr ve klme ortaya kar.Kurutulan bir masse flekillendirme suyunu tamamen kaybedinceyekadar klr. Boyutlardaki klme kil piflirildiinde de devameder. Bu kez klmenin nedeni, yapsndaki organik maddelerinyanmas, gazlarn uzaklaflmas, kristal suyun ayrlmas ve karmaflkkristal ve faz deiflimleri ile oluflan yeniden yaplanmadr. Birbaflka deyiflle, yapdaki ergitici feldispat ve mevcut safszlklarnergiyerek dier yksek scaklkta ergiyen tanecikleri kuflatmas ileyoun bir yap haline dnflmesi gerekleflir. Bu olaya karonunpiflmesi veya sinterlenmesi ad verilir ve bundan dolay seramikmalzeme pifltiinde klme gsterir [7-9]. fiekil 1-3 arlka %20, 25 ve 30 oranlarnda pegmatit, nefelin siyenit ve sodyum feldispatilavesi ile oluflan % toplu klme deerlerini gstermektedir.

3P X L

2 a2 x b

: Mukavemet (kg/cm2)P: Yk (kg)L: Mesnet aral (cm)a: Kalnlk (cm)b: Genifllik (cm)

DTA analizi Linseis Thermawaage L81 marka cihaz kullanlarak,5 C/dk stma hz ile 1000 C ye kadar yaplmfltr. Harkort testibtn bir karonun 15 C ile 145 C arasnda 10 defa evrimyaplp, sl floka dayanm zellii belirlenmifltir. Otoklav testinde,karolar otoklava yerlefltirilmifl 2 saat sre ile 16 C de 500 KPa

basn uygulanarak srn atlama zellii llmfltr.

Su emme, piflen rnn ak gzeneklerine alabilecei su olaraktanmlandndan su emmeyi etkileyen birok faktr vardr. Bunlar;kilin karakteri, safszlklar, presleme basnc, flekillendirme rutubetive rnn piflme scakldr [6].

Ham (yafl) mukavemet, kuru mukavemet ve piflme mukavemetinilmek iin karo numunelere 3 noktal eme testi uygulanmfltr.Mukavemet deerleri afladaki forml kullanlarak hesaplanmfltr.

DTA analysis was performed by using Linseis Thermawaage L81type instrument. In this measurement, maximum temperaturewas kept as 1000 C with a heating rate of 5 C/min. Harcourt testwas applied with 10 cycles between temperatures 15 C and 145C. By doing, thermal shock resistance was measured. In autoclave

test, tiles were placed in autoclave and cracking behaviour of glazedsamples was measured during 2 hours holding at 16C underpressure of 500 KPa.

=3P X L

2 a2 x b

: Strength (kg/cm2)P: Mass or pressure (kg)L: The distance between bars (cm)a: Thickness (cm)b: Width (cm)

3. RESULTS AND DISCUSSION

The reason why clays are showing shrinkage when they are driedis due to the evaporation of shaping water. As water evaporatesbetween clay grains, grains come closer and shrinkage takesplace. Dried masse continues to shrink until all shaping waterevaporates. During firing, shrinkage still continues. At this time,the reasons for such an attitude are firing organics, gasevaporations, the evaporation of crystal water and with complexcrystal and phase changes due to reconstruction. With another

saying, feldspar and other liquid forming impurities melt andsurround the refractory materials, by doing this, again shrinkagewas observed. This phenomenon is named as firing or sinteringof tile body. During this, tile is showing shrinkage [7-8]. Figs. 1-3indicate percentage of total shrinkages when 20, 25 and 30 wt %pegmatite, syenite and sodium feldspar added to starting recipes.

The maximum total shrinkage was observed in the case of syeniteaddition, since it has the highest alkali content. When the addedamount of three different materials increased, the total shrinkagewas observed to increase. In the presence of alkalis, the amountof formed liquid phase is high and evaporative characters materials

can evaporate easily. At the same time sintering can take placevery easily due to the materials easily dissolving and forming liquidphase.



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fiekil 7:Deiflen miktarlardaki pegmatitin (a) kuru ve (b) piflme mukavemetine etkisi.Figure 7. The effect of pegmatite on (a) dry and (b) firing strength.

fiekil 4: Deiflen oranlardaki pegmatitin su emme zelliine etkisi.

Figure 4. The pegmatite effect on water absorption.

fiekil 3: Deiflen oranlardaki sodyum feldispatn toplu klmeye etkisi.Figure 3. The sodium feldspar effect on total shrinkage

fiekil 5: Deiflen oranlardaki nefelin siyenitin su emme zelliine etkisi.

Figure 5. The syenite effect on water absorption.

fiekil 6: Deiflen oranlardaki sodyum feldispatn su emme zelliine etkisiFigure 6. The sodium feldspar effect on water absorption.

En yksek toplu klme deeri nefelin siyenitte gzlenmektedir.

Her bir ilavenin oranlar arttka % toplu klme artmaktadr.Bunun yannda sodyum feldispat ilavesi ile toplu klmede fazlabir artfl gzlenmemektedir. Nefelin siyenitte alkali oksit oranolduka yksektir. Bunu sodyum feldispat ve pegmatittirizlemektedir. Bu oranlara gre % toplu klme en ok alkaliieren nefelin siyenitte daha sonra sodyum feldispatta ve en azpegmatitte gzlenmektedir. Alkalilerin fazla olmas durumundasv faz oluflumu artmakta ve sv faz ierisinden uucu karakteresahip maddeler daha kolay uzaklaflabilmektedir. Ayn zamanda,cams faz ierisinde znebilen maddeler ve sv faz ile sinterlemedaha kolay olmaktadr. Alkali ierii yksek ilavelerde % topluklme miktar daha yksektir. Bu durumda oluflan cams faznviskozite davranfl uucu maddelerin uzaklaflmasnda veyounlaflma zerinde etkindir.

High level of alkali containing samples were showed very hightotal shrinkage %. At the same time the viscosity of glassy phaseis effective in evaporation of materials and densification.

fiekil 4-6 farkl oranlarda pegmatit, nefelin siyenit ve sodyumfeldispat ilavelerinde su emme deiflimlerinin yzde oranlarngstermektedir. Su emme grafiklerinden farkl oranlarda pegmatit,nefelin siyenit ve sodyum feldispat ilavelerinde, ilave edilen malzememiktar arttka su emme deeri dflmektedir. En dflk su emmedeeri nefelin siyenitte gzlenmektedir. Nefelin siyenit ilave edilmiflnumunelerin su emme miktarlarnn dflk olmasnn ak poroziteorannn dflk olmasndan kaynakland dflnlmektedir. Budurumda sz konusu numunelerin daha iyi sinterlendii ifadeedilebilir. Yer karosu standart su emme deerinin % 3 ve alt olduubilinmektedir. Burada, nefelin siyenitin arlka % 30 ilavesindeelde edilen su emme deerinin ~ % 2,7 olduu grlmektedir.

Figs. 4-6 are showing percentage of water absorption for pegmatite,syenite and sodium feldspar containing bodies. From waterabsorption graphs, with their incoorporation water absorptionswere observed to decrease.



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fiekil 10:Arlka % 25 pegmatit ilaveli numunenin DTA erisi.Figure 10. DTA curve of 25 wt % pegmatite added sample.

fiekil 8:Deiflen miktarlardaki nefelin siyenitin (a)kuru ve (b)piflme mukavemete etkisi.Figure 8. The effect of syenite on (a) dry and (b) firing strength

fiekil 9:Deiflen miktarlardaki sodyum feldispat (a) kuru ve (b) piflme mukavemete etkisi.Figure 9. The effect of sodium feldspar on (a) dry and (b) firing strength

fiekil 11:Arlka % 25 nefelin siyenit ilaveli numunenin DTA erisiFigure 11. DTA curve of 25 wt % syenite added sample.

fiekil 7-9 pegmatit, nefelin siyenit ve sodyum feldispat ilavesindekuru ve piflme mukavemetleri deerlerini gstermektedir. Her farkl ilavede arlka yzde oranlar arttnda kuru mukavemetazalmaktadr. En dflk kuru mukavemet deeri nefelin siyenitilaveli numunede gzlenmektedir. Nefelin siyenitten sonra endflk kuru mukavemet sodyum feldispat ilaveli numunedegzlenmifltir. En yksek kuru mukavemet deeri ise pegmatitilaveli numunede gzlenmifltir. Burada, bnyedeki SiO2 miktar ilekuru mukavemetin ters orantl olduu ifade edilebilir.

Yaplan ilavelerin miktar arttka piflme mukavemetleri artmaktadr.En yksek piflme mukavemet deeri nefelin siyenit ilaveli numunedegzlenmektedir. En dflk deer ise sodyum feldispat ilavelinumunede gzlenmektedir. Nefelin siyenitte piflme mukavemetininyksek oluflunun sv faz sayesinde younlaflmann daha fazlaolmasndan kaynakland dflnlmektedir.

The lowest absorption was observed for syenite containing ones.It is thought that this happens because of low level of open porosityin structure.In this case, we can say that this material was wellsintered. The standard value of water absorption is known as 3 %

and below. At 30-wt % syenite addition, water absorption valuewas found ~2.7 %. This value is appropriate for standard.

Figs. 7-9 are exhibiting the dry strength and fired strengths ofpegmatite, syenite and sodium feldspar added bodies. With eachdifferent addition, dry strength was observed to decrease. Thelowest dry strength was found in syenite added bodies. Aftersyenite, sodium feldspar showed lowest value. The highest drystrength value was observed for pegmatite added samples. It canbe said here; dry strength has transverse relationship with increasingSiO2 content.

fiekil 10 arlka % 25 pegmatit ilaveli numunenin DTA erisinigstermektedir. Burada 100 C de fiziksel su , 300 C de kristalsuyu uzaklaflmaktadr ve 570 C de kuvars dnflmgzlenmektedir. fiekil 11 arlka % 25 nefelin siyenit ilavelinumunenin DTA erisini gstermektedir.

The highest fired strength value was observed with syenite input.However, the lowest value was observed in the case of sodiumfeldspar incoorporation. High amount of alkali in syenite helps andmakes easy densification and firing.



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fiekil 12:Arlka % 25 sodyum feldispat ilaveli numunenin DTA erisiFigure 12. DTA curve of 25 wt % sodyum feldispat added sample

Bu eride de pegmatitte gzlenen davranfllarn benzerigzlenmektedir. fiekil 12 arlka % 25 sodyum feldispat ilavelinumunenin DTA erisini gstermektedir. Burada da dier ikisindeoluflan benzer davranfllar gzlenmektedir.

izelge 6-8 pegmatit, nefelin siyenit ve sodyum feldispat ilavelerindeHarkort ve otoklav deneyi sonular verilmektedir. Bu deneylersonucunda her bir ilave iin olumlu sonu gzlenmifltir.

4. GENEL SONULAR

Kullanlan her bir malzemenin standart yer karosu zellikleri iinsalad avantajlar ve dezavantajlar mevcuttur. Pegmatit ve sodyumfeldispat standartlara uygun toplu klme ve kuru mukavemetzellii salamfllardr. Nefelin siyenit standartlara uygun su emme

deeri salarken (~ % 2.7), pegmatit ve sodyum feldispat ilavelinumunelerin su emme deerleri standartlarn zerindedir. Bu daistenmeyen bir zelliktir. Piflme mukavemetleri herbir numuneiin standartlarn zerindedir. Toplu klme en yksek nefelinsiyanitte gzlenmifltir, bu durum nefelinin kullanm asndan birdezavantajdr. Pegmatit ve sodyum feldispatn toplu klmedeerleri birbirine yakn olup standartlarn dflndadrlar. Bualflmann sonucu olarak, bu hammaddenin yer karosubnyesinde kombinasyonlar halinde kullanlmas nerilmektedir.

TeflekkrYazarlar Kale Seramik, anakkale Kalebodur Seramik San. A.fi.ye teknik desteklerinden dolay teflekkr ederler.

Fig.10 is showing DTA curve for 25 wt % pegmatite added sample.From this curve, at 100 C, physical water is evaporating, at 300C, cyrstal water is released and at 570 C, quvars transformationtakes place. Fig. 11 is showing DTA curve for 25 wt % syenite added

sample, from this curve, one can also see the same behaviors asmentioned for pegmatite. Fig. 12 is showing DTA curve for 25-wt% sodium feldspar added sample. In this case, we can also seethe similar manner in Figs.10-11.

Tables 6- 8 are showing the Harcourt and autoclave tests resultsfor the pegmatite, syenite and sodium feldspar added samples.According to these tests, all samples found satisfactory.

4. GENERAL RESULTS

The used raw materials have both advantages and disadvantagesfor standard tile body production. Pegmatite and sodium feldsparshowed suitable total shrinkage and dry strength according tostandards. As syenite is providing appropriate water absorption

(~2.7 %), the other two additives values were found to be over thestandard. Firing strengths for each sample were found to be withinstandard values. Even more, their firing strengths were found tobe higher from standard value. The highest total shrinkage wasobserved in syenite added samples, this effect is a disadvantageof syenite. The total shrinkages of pegmatite and sodium feldsparbeing close to each other are far from standards. As a result ofthis study, we propose to use these three materials in a suitablecombination.

AcknowledgmentThe authors would like to thank to the Authorities of Kale Ceramic,anakkale Kalebodur Ceramic Industry for their technical supports.


[1]. Tre, .,Siyenit Hammaddesinin Seramik Bnyelere Etkilerininncelenmesi, Yksek Lisans Tezi, Anadolu niversitesi, 1999.[2]. Youssef, N.F., Abadir, M.F., and Shater, M.A.O., Utilizationof Soda Glass (Cullet) in the Manufacture of Wall and Floor Tiles,J. of Eur. Ceram. Soc., Volume 18, Issue 12, 1721-1727, November1998.[3]. Aksoy, D.,Dnyada ve Trkiyede Feldspat ve Nefelinli Siyenit,M.T.A. Gn. Md. Arafltrma Planlama Koord. Dairesi, EkonomikEtdler Birimi, Ankara, Mays 1996, (eviri) Bolger, R., IndustrialMinerals, May 1995.[4]. Clarke, M.L., Rendell, H.M., Infra-red Stimulated

Luminescence Spectra of Alkali Feldspars, RadiationMeasurements, Volume 27, Issue 2, 221-236, April 1997.

[5]. Uz, B., Mineraller, Kurtifl Matb., stanbul, 1990.[6]. Correia, S.L., Hotza, D. and Segadaes, A.M., SimultaneousOptimization of Linear Firing Shrinkage and Water Absorptionof Triaxial Ceramic Bodies Using Experiments Design, Ceram.International, Volume 30, Issue 6, 917-922, 2004.[7]. Dana, K., Das, S. and Swapan, K.D., Effect of Substitution ofFly Ash for Quartz in Triaxial Kaolin- Quartz-Feldispar System,J. of Eur. Ceram. Soc. , Volume 24, Issues 10-11, 3169,September 2004.[8]. Wall, F., Zaitsev, A.N., Mariano, A.N., Rare Earth Pegmatitesin Carbonatites, Journal of African Earth Sciences, Volume 32,Issues 1, A35-A36, January 2001.

[9]. Cornelius, S., Hurlburt, J.R.,Mineraller, Cilt2, eviren : nan,K., Tanyolu, E., Doyuran Matbaas, stanbul, 1982.



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GRfi

Gzenekli malzemelere olan ilgi yeni retim yntemleri ve yeniuygulama alanlarndaki geliflmelere paralel olarak her geen gnartmaktadr. Gzenekli seramikler geleneksel s yaltm ve yap

malzemesi olarak kullanlagelmifltir. Yksek scaklk, kimyasaldayanm ve yksek yapsal homojenlik gibi ilgi ekici zelliklerindendolay, bu uygulama alanlarnn dflnda filtre malzemesi, katalizrdestek malzemesi ve membran formunda da kullanlmaktadr.Gzenekli seramikler as seramikler ve kpk seramiklerdiye iki ana grup altnda toplanabilir. Ksaca, as seramikler,seramik matris ile evrilmifl ve birbirine kenetlenmifl bir gzenekliyap iken kpk seramikler srekli bir seramik matris iindedalmfl kapal gzeneklerden meydana gelmektedir. Szkonusuyaplarn geirgenlikleri farkl olup, as trde yksek, kpkslerdedflktr. Geirgenlikteki bu farkllk hcre yaplarnn ak veyakapal olmasndan kaynaklanmaktadr [1]. Gzenekli ve a yaplmalzemeler dflk arlk, yksek yzey alan ve dflk sl iletkenlikgibi dikkat ekici zelliklere sahiptir. As yapdaki gzeneklimalzemelerin en yaygn uygulama alanlar dkm filtreleri, dizel

motor egsoz filtresi, katalizr destek malzemesi ve endstriyelscak gaz filtresidir. Hem as hem de kpk seramikler hafif plakamalzemesi, yaltm malzemesi, scaklktan koruma malzemesi vegaz yakma odasnn duvar malzemesi olarak kullanlmaktadr.

1. SIVI METALN FLTREDEN GERLMES

Demirdfl metallerin daha karmaflk uygulamalarndaki artfllabirlikte metalin kalitesinde daha belirgin geliflmelerin salanmasnaolan ihtiya da artmaktadr. Kalite gvence programlarnn dadevreye sokulmasyla rekabet edilebilir fiyat dzeylerinde, dahayksek kaliteli dkmlere olan talep kendini daha belirgin birbiimde hissettirmifltir. Bu tr gereksinimler, paralarn tekrarifllenme orannn, hurdaya ayrlan miktarn ve hata tespiti iin

harcanan srenin mmkn olduunca dflk seviyelere naslekilebilecei ynndeki alflmalara olan ilgiyi artrmfltr.

Metalik olmayan kalntlar yapda oksit tabakas, oksit paracklar,karbrler, nitrrler, borrler, fosfatlar, slfitler, metaller araskalntlar ve eflitli kirlilikler fleklinde yer alabilirler. Kayna okeflitli olabilen kalntlarn en nemlileri aflada sralanmaktadr.Bu tr kalntlar dkmhanelerde oluflan hurdalarn ananedenidir[2]:

i. Bafllang hammaddeleriii. Frn refrakterleriiii. Akflkanlafltrc hammaddelerden kaynaklanan atklariv. yi denetlenememifl sl ifllemlerv. Aktarma ve dkme aflamalarnda oluflan oksitler

vi. Kalp malzemesi ve kaplamalarvii. Metal besleme sistemindeki trblans akfl

INTRODUCTION

The interest in porous ceramics has increased concurrently withnew processes and applications. Traditionally porous ceramicshave been used as thermal insulation and building materials. In

addition to these areas because of their attractive properties,including good temperature and chemical resistance and highstructural uniformity, they are being used as filters, catalyst supportsand membrane applications. Generally porous ceramics can begrouped in two basic categories: reticulate ceramics and foamceramics. Briefly, a reticulate ceramic has a porous structurecomprised of interconnected voids enclosed by a web of ceramicwhile a foam ceramic has closed voids within a continuous ceramicmatrix. Permeability of these structures are different, high andlow in reticulate and foam ceramic structures, respectively. Thedifference between these porous structures is due to the open-versus closed-cell structures [1]. These porous network structureshave remarkable properties such as relatively low mass, highsurface area and low density, and low thermal conductivity. Themost common applications of reticulate porous ceramics aremolten metal, diesel engine exhaust filters, catalyst supports andindustrial hot-gas filters. Both reticulate and foam ceramics areused as light-structure plates, thermal insulating materials, fireprotection materials, and gas combustion burners.

1. LIQUID METAL FILTRATION

Non-ferrous metals have an increasing usage for more sophisticatedapplications and this fact has led to ever-greater demands formajor improvements in metal quality. By the introduction of QualityAssurance programmes demand for higher quality castings atcompetitive prices, has been further supported. These requirementsincreased interest in ways of keeping the amount of reworking,scrap and inspection times as low as possible.

Presence of non-metallic inclusions can take a range of formsincluding films and particles of oxides, carbides, nitrides, borides,phosphates, sulphides, inter-metallic inclusions and sludge, whichcan originate from a number of sources including the following,is one of the basic causes of scrap in the foundry [2]:

i. Charge materialsii. Furnace refractoriesiii. Flux residuesiv. Poorly controlled metal treatmentsv. Oxide produced in transfer and pouringvi. Mould materials and coatingsvii. Turbulent flow through the running system

As a result of these inclusions following events are occurred:i. A reduction in mechanical propertiesii. Poor machinability with consequent high tool wear

Seramikdkm filtreleriCeramic molten metal filters

Arafl. Gr. AyfleKalemtafl

Anadolu niversitesi,Mhendislik-Mimarlk FakltesiMalzeme Bilimi ve Mhendislii Blm, Eskiflehir

Yrd. Do. Dr. GrsoyArslan

Research Assist. AyfleKalemtaflAnadolu University, Faculty of Engineering and Architecture,Department of Materials Science and Engineering, Eskiflehir

Assist. Prof.GrsoyArslan


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iii. A reduction in metal fluidityiv. Poor surface quality affecting subsequent finishing treatmentsv. High scrap ratesvi. Lack of pressure tightness

Inclusions have severe effects on foundry profitability by causinggreater proportion of rejects, increased costs of rectification, andcastings of poor appearance. Thus to solve this problem effortshave been made such as changing refractory material, meltingpractices, pouring procedures and gating systems. Only partialsuccess is obtained by all these alterations however varying fromcase to case [3]. Consequently increasing use of ceramic filtershas ensured the cleanliness of the majority of cast metals andalloys. Running system can be used for its primary purpose ofmetal delivery to the castings cavity whilst ceramic filter is usedto provide inclusion-free castings and improve yield by overcomingmost of the previous problems experienced at filtration process[4].

In non-ferrous foundries, energy and cost savings can be achievedby the use of filters for straining the molten metal prior to casting.Many foundries do not yet filter, perhaps because they are unawareof the likely cost benefits. Inserting a disposable ceramic filter justahead of the mould can provide a cost-effective way of improvingproduct quality and reducing operating costs. Studies were madein aluminium and copper-based alloy foundries, which provedconclusively significant cost savings for little expenditureon anaverage about $800/year per tone of good castings. Other non-energy related savings were almost as high as well [5].The cost of adjusting patterns or dies to accommodate filters isminimal. The benefits of filtering molten metal prior to castinginclude:

Higher casting quality (and hence customer satisfaction)

Reduced scrap and reject rates Higher overall yields and Reduced energy, metal, sand and labour costs

2. TYPES OF MOLTEN METAL FILTERS

Various kinds of filters are available including: strainers cores,sieve cores, filter clothes, steel gauze screens, wire wool, cellularfilters and ceramic foams. In Figure 1 different types of ceramicmolten metal filters are seen. Depending on the number of poresper unit (ppi=pores per inch) porous ceramic filters are classifiedranging from 3 ppi to 40 ppi as rough and fine, respectively. Generallyporosity content of the filters varies between 75 to 80%. Effectiveand efficient filtering can be achieved using high numbered filters

in molten metals with high melt flow and low surface tension [6].

Steel gauze screens and filter clothes have been used in the primaryand secondary aluminium industries for several years. In the non-ferrous metal industry different filters such as open weave fibreglasscloth, steel gauze screens and wire wool have been used with onlylimited success. These materials have an effect in reducingturbulence but are not particularly effective in filtering fine non-metallic from the metal, also in the case of steel containing filtersthe problem of iron contamination on remelt can become asignificant factor.

Strainer cores have been used extensively in the iron-casting field,but are not really a filter as such. Principally these materials aredesigned to act as a choke in the system, primarily positioned at

the base of the down sprue, to affect a full sprue and cause slagflotation.

Bu kalntlar yznden flu olumsuz sonular ortaya kmaktadr:

i. Mekanik zelliklerde ktleflmeii. Zayf ifllenebilirlik ve bunun sonucu takm eliklerinde yksek aflnmaiii. Metalin akclnda azalma

iv. Rtufl ifllemlerini etkileyen kt yzey kalitesiv. Yksek skarta oranvi. Basn dayanmnn olmamas

Kalntlar, skarta orann ve onarm masraflarn artrmak ve dekt grnml dkmlere neden olmak suretiyle dkmhanelerinkarll zerinde ciddi olumsuz etkilere yol amaktadr. Dolaysyla,sorunun giderilmesi amacyla refrakter malzemesinin deifltirilmesi,dkme koflullarnn ve besleme sistemlerinin yenilenmesi gibieflitli abalar sarf edilmifltir. Ancak, btn bu tedbirlere ramenelde edilen baflar ksmi olmufl ve durumdan duruma da deifliklikgstermifltir [3]. Sonuta, seramik filtrelerin artan oranda kullanmdaha temiz dkm metal ve alaflmlarn retimini beraberindegetirmifltir. Bylece besleme sistemi birincil amac olan dkmboflluuna metali aktma grevini stlenirken, seramik filtrekalntsz dkmlerin elde edilmesini salamakta, ayrca filtrasyonsrecinin belli bafll problemlerinin ounu ortadan kaldrarakverimi artrma grevini yerine getirmektedir [4].

Demir dfl metal dkmhanelerinde, ergimifl metali dkm ncesifiltrelerden szmek suretiyle enerji ve maliyet kazanmlarsalanabilmektedir. Ancak, buna ramen bir ok dkmhane,belki de salayaca maliyet dflflnden habersiz olduu iin,ergimifl metali halen filtre ile szmemektedir. Atlabilir zelliktebir seramik filtrenin tam kalbn azna yerlefltirilmesi ile hem rnkalitesi ekonomik bir flekilde arttrlabilir hem de iflletme maliyetiazaltlabilir. Kk yatrmlarla belirgin maliyet dflfllerininsalanabileceini tartflmasz bir flekilde ortaya koyan alflmalaralminyum ve bakr esasl alaflmlar dken dkmhanelerde

gereklefltirilmifltir. Bu alflmalara gre bir ton iyi dkm baflnaortalama 800 $lk bir tasarruf salamak mmkndr. Enerjikaynakl olmayan dier kazanlar da neredeyse ayn dzeydegerekleflmifltir [5]. Filtrelerin montaj iin kalplarda yaplmasgereken ayarlamalar iin gereksinim duyulan harcamalar okdflk dzeylerdedir.

Ergimifl metalin dkm ncesi filtrelenmesi ile salanacak yararlarflu unsurlar iermektedir:

a b

c d

fiekil 1:Seramik eriyik metal filtre eflitleri (a) preslenmifl seramik filtre [7], (b) kpkseramik filtre [7], (c) seramik membran filtre [8], (d) ekilmifl (extruded)seramik filtre [9].

Figure 1: Ceramic molten metal filter types (a) pressed ceramic filter [7], (b) foamceramic filter [7], (c) ceramic membrane filter [8], (d) ceramic extruded filter [9]


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Daha iyi bir dkm kalitesi (ve dolaysyla da yksek mflterimemnuniyeti) Daha dflk hurda ve skarta oranlar Daha yksek toplam verimlilik ve

Daha dflk enerji, metal, dkm kumu ve iflilik maliyeti

2. ERGMfi METAL FLTRE TRLER

Filtre maa, elek maa, elik tl elekler, tel iplik, hcre filtre veseramik kpkler gibi ok eflitli filtre trleri bulunmaktadr. fiekil1de seramik eriyik metal filtrelerin deiflik trleri gsterilmektedir.Gzenekli seramik filtreler, birim uzunluk baflna dflen gzeneksaysna bal olarak kaba ve ince diye iki grupta toplanmaktadr.Genelde filtrelerin gzenek oran %75-80 arasnda deiflmektedir.Eriyik akfl yksek ve yzey gerilimi dflk olan eriyik metallerdeetkin ve verimli bir filtreleme ifllemi ince filtreler ile yaplabilir [6].

elik tl elekler ve filtre keeleri alminyum endstrilerindeyllardan beri kullanlmaktadr. Demir-dfl metal endstrisinde

ak rlmfl cam fiber keeleri, elik tl elekler ve tel yn gibieflitli filtreler ancak snrl bir baflar ile kullanlagelmifltir. Bu filtremalzemeleri her ne kadar trblans azaltmada yararl iseler deince, metalik olmayan safszlklarn metalden uzaklafltrlmasndaetkin olmamaktadr. Ayrca, elik ieren filtrelerde tekrar ergitmeaflamasnda meydana gelen demir kirlenmesi nemli bir sorunyaratabilir.

Filtre keeleri dkme demirlerde yaygn biimde kullanlmaklaberaber aslnda bir filtre malzemesi deildir. Temelde bunlarsistemde bir tkanma etkisi yaratmak zere tasarlanmfl olup, tambir yolluk ve cruf flotasyonunu salamak iin alt yolluun tabannayerlefltirilmektedirler.

Elek maalarn gzenekleri filtre maalarnkinden incedir ve svmetalin akarken gerinmesini salamak zere tasarlanmfllardr.Filtre keeleri, alminyum iin rlmfl cam fiber yaplardr veyksek scaklk uygulamalar iin (dkme demirler dahil) rlmflrefrakter cam keeleridir. Her ne kadar trblans azaltma eilimleriolsa da filtreleme verimleri ve filtre ile elek maalar gibi gzeneklialanlar nispeten dflktr. Ayrca, yeterli byklkte bir parannengel olmamas durumunda tkama grevini de stlenebilirler.rnein, elek maalar metal geifli iin yaklaflk % 45 civarndabir ak alana sahip iken keelerin ak alan yaklaflk % 25dir [4].

Hcresel filtreler, tipik olarak kare kesit geiflli bir ar peteiyapsndadrlar ve seramik duvarlarn ince olmas nedeniyle yaklaflk% 75e kadar varan bir gzeneklilie sahip olabilmektedirler.Hcresel filtrelerin hcre yaps eleme verimliliini snrlamaktadr.

Eleme verimlilii filtre yzeylerinde biriken kalntlardan nemlioranda etkilenmektedir.

Seramik kpk filtrelerin gnmzde kullanmda olan filtrelerarasnda en yksek etkinlie sahip filtre eflidi olduu ilerisrlmektedir. boyutlu a yaplar sayesinde metal akfl iinok dolambal bir gzergah oluflturmakta ve bylece de yksekbir filtrasyon verimlilii salamaktadrlar. Byle bir yap eriyik metalile seramik filtre arasnda olaanst yakn bir temasa yol amakta,bu sayede ok kk kalntlar ekim ve emilme yoluyla filtrenini duvar yzeylerinde birikmekte ve de metaldenuzaklafltrlmaktadr. Seramik kpk filtrelerin kullanmna iliflkintemsili bir akfl flemas fiekil 2de gsterilmifltir.

Seramik filtreler her ne kadar alminyum ve demir dkm

sektrlerinde yaygn bir kullanma sahip olsalar da elik sektrndeok daha az kabul grmektedirler.

Sieve cores have finer holes than strainer cores and in actual factare designed to strain the liquid metal as it passes through.

Filter clothes are woven fibreglass structures for aluminium and

woven refractory glass clothes for higher temperature applicationsincluding cast irons. Although they have a tendency to reduceturbulence, they have a low filtering efficiency and like strainercores and sieve cores, they have a small open area and could actas a choke, unless sufficiently large piece is used to counteractthis. For instance, sieve cores tend to have approximately 45%open area for metal passage and clothes approximately 25% [4].

Cellular filters have a typically honeycomb structure, with squaresection passages, which due to the thin ceramic walls can haveup to approximately 75% open area. Cell structure of cellular filterslimits its efficiency and relies heavily on the build-up of inclusionson the face of the filter to effect removal.

Ceramic foam filter is claimed to be the most highly efficient filter

currently in use. Pores of ceramic foam filters have a 3-D network,which provides a very tortuous path for metal flow thus providehigh filtration efficiency. This kind of structure allows extremelyintimate contact between the metal and the ceramic structure,which effects the removal of very small inclusions by attractionand absorption to the internal ceramic pore surfaces. Arepresentative flowchart for the usage of the ceramic foam filtersis seen in Figure 2.

Ceramic filters are widely used in the iron and aluminium alloycastings sector but they are accepted to a much lesser extent inthe steel sector. This is due to the two main problems. Firstly, thehigh pouring temperature of steel can lead to the catastrophic


fiekil 2 : Seramik kpk filtrelerin kullanm [10].Figure 2 : The usage of the ceramic foam filter [10]


23/24


Bu, temelde flu iki ana problemden kaynaklanmaktadr: eliinyksek dkme scakl, filtrenin dflk sl flok direnci nedeniyleaniden krlmasna neden olabilir. Daha nceki filtreleme ifllemlerininkalntlar ve crufun varl filtrenin dkmn ortasnda tkanmasna

yol amaktadr. Bu ikinci sorun eliin hzl souma eilimi yzndendaha da bymektedir. Filtrenin kapanmas durumunda, hemdkm hem de kalp hurdaya kmaktadr. Tipik metal dkmscaklklar ve seramik filtre malzemeleri izelge 1degsterilmektedir.

3. METAL DKM FLTRELERNN RETM

Poroz seramiklerin retiminde kullanlan ok sayda yntembulunmaktadr [12]: Kapslsz HIP (Scak zostatik Presleme), zelbir sl ifllem uygulanarak amur formda veya yafl halde kabarckoluflturulmas, reaksiyon sinterlemesi, ksmi younlaflma salamakamacyla sinterleme koflullarnn ayarlanmas, n sinterlemesiyaplmfl granl veya fiberlerin istiflenmesi, aerojel ve sol-jelmetotlar, eflitli organik katklarn pirolizi, polimerik snger yntemi.

failure due to thermal shock. Secondly, the presence of inclusionsand dross from earlier metal treatments causes the filter to blockpart way through mould filling. The latter problem is accentuatedby the rapid freezing of the steel. If the filter gets blocked, the

castings are mis-run and the mould and castings are scrapped.Typical metal casting temperatures and ceramic filter materialsare shown in Table 1.

3. PROCESSING OF MOLTEN METAL FILTERS

Numerous processing routes are available to realize porousceramics [12]: capsule free HIP, bubbles generation into a slurryor at a green state during a specific thermal treatment, reactionsintering, control of the sintering conditions in order to achieve apartial densification, stacking of pre-sintered granules or fibres,aero gel and sol-gel methods, pyrolysis of various organic additives,polymeric sponge method. Schwartzwalder et al firstly describedpolymeric-sponge technique in 1963. In Fig 3 [13] there is a generalflow chart, which describes the steps of polymeric-sponge technique.


This technique included the impregnation of a polymeric sponge

with ceramic slurry followed by a thermal treatment, which leadsto the burning out of the organic portion and to the sintering of theceramic skeleton. Many steps must be optimised to develop afoam product having the desired performances, namely: the choiceof the polymeric template; the preparation of the ceramic slurry;the impregnation; the thermal cycle comprising drying, burningout of the volatile components, sintering of the ceramic portion.A variety of open-cell, semi-closed and closed-cell sponge materialsare suited to replication process; their pore size determines thepore size of the ceramic foam after the shrinkage linked to thefiring step. The sponge should volatilise at low temperature withoutyielding noxious by-products; in addition, it must readily soften andburn off, without inducing sensible residual stresses and disruptingthe non-sintered ceramic network. Its resiliency, its hydrophobicbehaviour and its ability to be uniformly covered are other significant

properties. Many polymeric-sponge materials can satisfy theserequirements, namely poly (urethane), cellulose, poly (vinyl chloride),poly (styrene), latex. In some cases, sponge like polymers (likepolysilanes, polycarbosilanes) have been used to prepare ceramicfoams by pyrolysis: these pyrolyzed porous networks were thenimmersed in ceramic slurries to obtain composite foam.

One of the key steps of this process is undoubtedly the elaborationof appropriate ceramic slurry able to uniformly cover the polymericwalls, to easily sinter in a dense ceramic network, able to withstandthe in-use constraints. Common slurry for this application is formedby a ceramic powder, a dispersion medium (generally water) andsome additives. A pure, fine ceramic powder having a narrowparticle size distribution is usually requested: dimensions lowerthan 45 m are common, and generally the mean particle size isclose to few microns. In addition, equiaxial particles should leadto a more

Polimerik snger yntemi ilk olarak Schwartzwalder ve ark.

tarafndan 1963 ylnda bilim dnyasna sunulmufltur [13]. fiekil3de polimerik snger ynteminin basamaklarn gsteren genelbir akfl flemas verilmektedir. Bu teknikte polimerik sngere birseramik amuru emdirildikten sonra organiklerin yanmasn veseramik yapnn sinterlenmesini salamak amacyla bir sl ifllemuygulanr. stenen performansa sahip kpk rnn eldeedilebilmesi iin pek ok basaman zenle gereklefltirilmesigerekir: Kullanlacak polimerik malzemenin seimi, seramikamurun hazrlanmas, emdirme ifllemi, kurutma, organiklerinuzaklafltrlmas ve seramik yapnn sinterlenmesi basamaklarnierir. ok eflitli ak, yar kapal ve kapal hcreli sngermalzemelerinin kullanlmas mmkndr. Seilen sngermalzemesinin por boyutu piflirme sonras meydana gelen ekmeile beraber seramik yapnn por boyutunu belirler. Sngermalzemesinin dflk scaklklarda zararl yan rnler

oluflturmakszn buharlaflmas istenir. Bununla birlikte sngerinkolayca yumuflamas ve yanmas, yapda nemli oranda kalntgerilme oluflturmamas ve sinterlenmemifl a yapsnda flekilbozukluklarna yol amamas istenir. nemli dier zellikler iseesneklik, su sevmezlik ve homojen bir flekilde kaplanabilmefleklinde sralanabilir. Bu zellikleri salayan ok sayda sngermalzemesi mevcuttur. rnein, poliretan, selloz, polivinil klorr,polistrin, lateks. Baz durumlarda piroliz yntemiyle seramikkpklerin retiminde sngerimsi polimerlerin (rnein, polisilanlar,polikarbosilanlar) de kullanlabildii bilinmektedir. Piroliz edilenbu poroz

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