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PROPERTIES OF ‘ANCORDENSE’

PROCESSED HIGH PERFORMANCE

MATERIALS

A.J.Rawlings et al. (Hoeganaes Corp, Riv-

erton, New Jersey, USA)

Properties of Ancordense processed

materials were analyzed in detail, the

evaluation including strength, impact and

fatigue. Tests were carried out on

conventionally and high temperature

sintered alloys in as-sintered and heat

treated conditions.

tomization

IMPULSE ATOMIZATION FOR

ECONOMY AND FLEXIBILITY IN

POWDER PRODUCTION

H.Henein, L.C.Marin. (University of Alberta,

Canada.)

The Impule Atomization Process was

described. This was reported to allow

control of particle size and size

distribution, morphology and

microstructure. Examples given included,

Cu, Zn, Al and Al alloys. Process economics

were discussed.

A COMPACT ROTATING DISC

ATOMIZER FOR PRODUCTION OF

REACTIVE POWDERS

M.G.Osbome, LEAnderson. (Ames Labora-

tory, USA)

A new centrifugal atomizer was

described. The device uses spray

quenching and was used for rare earth

metals and alloys for magnetic and

electrical uses. The method allows

increased passivation of rare earths which

results in less oxidation of the powders.

CENTRIFUGAL DISPERSION OF

METALLIC BARSTOCK IN INDUCTIVE

PLASMA

F.Folio et al. (University of Clermont-

Ferrand, France.)

A novel atomizer for producing high

purity, fine metal powder from bar was

described. As the bar is drawn into the

machine it is inductively heated to below

the melting point and plasma melted.

Molten metal droplets are atomized on a

dispersion head rotating at 60 000 rpm.

The particles solid@ in Ar. Results were

discussed for industrial potential.

A STUDY OF TWO STAGE

ATOMIZATION

P.Cooper, J.D.Ayers. (Naval Research La-

boratory, USA)

A two-stage atomization process was

described. In stage 1 a liquid metal stream

is impact atomized by spinning impellers.

The resulting spray is further atomized by a

repidly rotating cup containing a

continuous oil film. Tests on Sn were

described. The final powder size was

38 MPR January 997

shown to be l/4 of that atomized in the

first stage only. Mechanisms were discussed

with regard to particle morphology.

A NOVEL INTERNAL MIXING GAS

ATOMIZER FOR PRODUCTION OF FINE

POWDER

JJDunkley, M.S.Sheikaliev. (Atomizing Sys-

terns Ltd., Sheffield, UK)

Types of atomizer nozzle, close coupled,

free fall and internal mixing, were

compared and discussed with reference to

efficiency. It was reported that a new

internal mixing nozzle had been used to

make powders of similar size to products of

other nozzles but at markedly lower gas

flow rates and pressures.

Fatigue

EFFECTSOFPORESTRUCTUREON

BENDING FATIGUE STRENGTH OF

SINTERED STEEL

P.Beiss, M.Dalgic. (Inst. for Materials

Science, Germany.)

Bending fatigue strength of sintered

4%Ni-1.5%Cu-0.5%Mo steel, made from

water atomized or sponge Fe powder, with

alloy elements diffusion bonded, sintered at

1120 to 1280°C to densities of 6.2 to

7.0 gm.cm-3, was investigated up to lo7

cycles. Alloys made from atomized powder

were superior. Results were correlated with

pore structures.

ASSESSMENT OF PERFORMANCE OF

SINTERED CRANKSHAFT BEARING

CAP

A. Romero et al. (Sintermetal SA Ripollet,

Spain.)

Responsibility for part design was

discussed and the tendenncy for PM

designers to be involved with part

function in a system was noted. The case

of an automotive part was used as an

example of how this was done. Studies

entailed strain guage measurement, finite

element analysis, scatter in properties and

derivation of safety margins. Safety factors

were verified by fatigue testing simulating

service conditions.

Refractory and hard

materials and alloys

SINTERING OF TUNGSTEN CARBIDE-

NICKEL CONTAINING CHROMIUM

CARBIDE

G.S.Upadhyaya, D.Banerjee. (Indian Inst. of

Technology, India)

Effects of Ni as a replacement for Co in

WC-lO%Co, on densification and of 2%Cr3Cz

were investigated. Ni was reported to

hinder densification and to reduce

hardness. The use of CrsCz was shown to

make up the loss in hardness and to

increase transverse rupture strength and

corrosion resistance.

FINITE ELEMENT SIMULATION OF

SINTERING OF CEMENTED CARBIDE

COMPACTS

DBouvard, O.Gillia. (Inst. National Poly-

technique, Grenoble, France.)

Stresses and shape changes during

sintering of metals and ceramics were

discussed. Sintering of WC-Co was

simulated by a finite element ‘ABAQUS’

program in an effort to predict the final

shape of a compact. Parameters were

determined by experiment. A range of part

geometries was considered. Predicted and

measured results were compared.

N S TU

OPTIMIZATION OF

SINTERING BY GAS PHASE CONTROL

G.Leitner et al. (tiunhofer Inst., Dresden,

Germany.)

It was reported that thermal analysis

and mass spectroscopy had been used to

study out- gassing and sintering of hard

materials. Volatile products of dewaxing

and sintering were characterized with

regard to temperature. Various processes

were shown to affect the C balance with

resultant detrimental property changes.

Methods of control were shown.

THREE-DIMENSIONAL

MICROSTRUCTURES OF TUNGSTEN

HEAVY ALLOYS SINTERED IN

MICROGRAVITY

R.G.Iacocca, R.M.German. (Pennsylvania

State University, Pennsylvania, USA)

It was reported that use of advanced

image analysis techniques had made it

possible to construct 3-dimensional

images by sectioning of microstructures at

discrete depths. This had been applied to W

heavy alloys, which had been sintered in

microgravity conditions, to analyze

connectivity, contiguity grain shape and

pore morphology.

HOT EXPLOSIVE COMPACTION OF

TUNGSTEN-TITANIUM AND

MOLYBDENUM-TITANIUM ALLOYS

LJ.Kecskes. (US Army Research Laboratory,

USA)

A novel hot explosive compaction

technique, app ed to W-Ti and MO-Ti

powders, was described. The metal powder

mix was surrounded by a calculated

quantity of the exothermic material which

when ignited produced heat and shock

waves to consolidate the metal powder to

near full density. Features of the process

and microstructures were discussed.

HOT SHOCK-WAVE COMPACTION OF

HARDMETALS AND TUNGSTEN

HBAVY ALLOYS

AB.Peikrishvili et al. (Academy of Sciences,

Republic of Georgia.)

A study of high temperature and

pressure shock-wave compaction of WC-Co

and W-Ni-Fe alloy powders was described. It