Application of fine-grained tungsten carbide based cemented carbides

Application of fine-grained tungsten carbide based cemented carbides

MANUFACTURE TO NEAR-NET OF TUNGSTEN-COPPER SHAPE COMPOSITES Y. Kai et al. (Nippon Tungsten Co., Fukouka, Japan). Nippon Tungsten Rev., Vol 27, 19...

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MANUFACTURE

TO NEAR-NET

OF TUNGSTEN-COPPER

SHAPE

COMPOSITES

Y. Kai et al. (Nippon Tungsten Co., Fukouka, Japan). Nippon Tungsten Rev., Vol 27, 1995, 10-17. Production of W- (10 to 40) %Cu parts, to close dimensional tolerances, by liquid phase sintering or Cu infiltration was investigated. It is reported that parts could be made in W-(15 to 27)YKu with minimal shrinkage from a blend of 1 and 8 urn powder and infiltration.

Hard materials and too/ steels A HISTORY OF FINE-GRAINED HARDMETALS G.E. Spriggs (Rusheen, Castlemain, Ireland). Znt. J. Refi-uctory Metals and Hard Muteriuls, Vol 13, No 5, 1995, 241. 255. The scientific and technological development of fine-grained hardmetals historically

reviewed. 1929 is noted as the

year of identification

Electrical and magnetic ma teriak

the particle size which can be produced. The role of milling is discussed with reference to uniformity of compacts and inhibition of grain growth during sintering

of some aspects of WC

grain refinement and by 1939 the beneficial grain relining effects of VC and TaC had been established. Changes in the definition

A TECHNICAL ECONOMIC ANALYSIS OF MAGNETS AND MAGNETIC MATERIALS

of ‘fine’ are considered, going from pm sizes in early years to nm sizes more recently. The author asks if this is the end of the story.

T. Abraham

APPLICATION

(Business Communications

Co,

Norwalk, Connecticut, USA). Int. J. Powder Metullurgy, Vol 31, No 2, 1995, 133-136. The commercial magnetic magnet

CARBIDE BASED CARBIDES

status of hard and soft

materials is reviewed. Permanent alloys

TUNGSTEN CEMENTED

OF FINE-GRAINED

considered

included

hard

L.J. Prakash (PM Pulvermetall GmbH, Rottenburg, Germany). Znt. J. Refructory Me-

ferrites, Sm-Co, Fe-Nd-B and Alnico. Soft materials were Fe-% electrical steels,

tals und Hard

amorphous

It is noted that sub-micron grade cemented carbides account for 10.15% of

feromagnetic

It is considered

alloys and Fe-Ni.

that

with

continuous

further improvements numerous applications will be found.

novel

1995, 257-264.

the market being characterized

properties

of Science, Beijing,

PM Technology, Vol 13, No 1, 1995,

3-7. (In Chinese.) It is reported that Ar atomized Fe-Nd-B powder consisted of a tetragonal NdzFe,,B phase. The compared

magnetic properties with powder made

comminution

of cast material

MECHANISM OF IMPROVEMENT CORROSION RESISTANCE OF TERNARY NEODYMIUM-BORON

are by

OF

Corporation,

Chiba, Japan).

DIFFUSION

BONDING

CARBIDE ON TO NODULAR CAST IRON BY HOT ISOSTATIC PRESSING C. Feixiong,

L. Shikui

(Central

Iron and

Steel Research Inst., Beijing, China). PM Technology, Vol 13, No 1, 1995, S-13. (In Chinese.) reported of

that

direct

cemented

diffusion

carbide

on

to

and

the

characteristics

bond are

(In

between

phases

in

At pH above 5.8 by a passive film.

performance described. modulus

of bonded

diamond

It is reported is a controlling

TERMINOLOGY

Young’s

factor in bonding.

TESTING

IMAGING AND MODELS GRAINED HARDMETALS B. Roebuck Teddington,

tools are

that

PROPERTIES FOR FINE-

(National Physical Laboratory, Middlesex, UK). Znt. J. Kefiac-

tory Metals and Hard Materials, Vol 13, No 5, 1995, 265-279. The hardness of WC hardmetals, particle

for

size

and

powders

of

and

it

relative

availability

is discussed.

standardization

emphasized

the

of

The need

terminology is

noted

is that

improvements in the technology of testing and characterization are required. These issues and models for prediction of hardness and magnetic properties from grain size are considered,

the Hall-Petch

relationship in particular. The use coercivity measurements for estimation

of of

grain

in

size

and

the

are are

caution

mentioned.

critically

needed

Published

reviewed

with

regard to the need for standardization

of

for grain size measurement. OF BORON CARBIDE

MANUFACTURE

S.M. Joo et al. (Chungnam

National

lltri

tory Metals and Hard Materials, Vol 13, No 5, 1995, 281-296. Aspects and liquid

of powder production, milling phase sintering of WC based

Synthesis of B,C was investigated a11(1is shown to be possible by reacting :! 1i;ir.l~

materials

are

BzO:r, 6 to 7 parts Mg and 1 to 1.4 parts 01’ C. The B,C particles are showu IO I),* spherical and pure. ParticI(b si/.cb is

production

to be more effective than Co against pitting.

particle

of

discussed. WC

are

growth considered.

that 50-150 nm represents

1996

bonding

versity, Daejeon, Korea). J. Korean Ztrsl. u/’ Metals, Vol 32, No 10, 1994, 1243-1249. (III Korean.)

Keplacement of Fe by Ni and Co enhances corrosion resistance at pH2.7. Ni is shown

MPR February

of

FROM OXIDE BY SELF-PROPAGATING HIGH TEMPERATURE SYNTHESIS

W.D. Schubert et al. (Technical University of Vienna, Vienna, Austria). Znt. J. Refiuc-

40

and

mechanisms

cutting performance. Investigations of mechanical properties and cutting

PREPARATION

ASPECTS AND LIMITS OF ULTRAFINE TUNGSTEN CARBIDE POWDER AND

Ni-Ti) -B magnets had been elucidated with some improvements made. These are attributed to small differences in of pH2.7. is inhibited

chemical

methods

HARDMETAL

solutions corrosion

with the is and

equations

described fracture

powder

matrix in cutting tool materials discussed with respect to physical

structures

It is reported that the mechanism of corrosion resistance of sintered Nd- (Fe-Co-

potential

449-453. (In Japanese.) Bonding of diamond

extrapolation

are

ON

OF

T. Fujimori et al. (Chiba Inst. of Technology, Narashino, Japan). J. Japan Sot. Powder and Powder Metallurgy, Vol 41, No 4, 1994,

nodular cast iron had been achieved by HIP using Ni foil as an interlayer. Interface strength and evaluated.

OF THE MATRIX

CUTTING PROPERTIES DL4MOND TOOLS

ultraline

OF CEMENTED

OF MECHANICAL

J. Japan Inst.

ofMetals, Vol 59, No 2, 1995, 206-212. Japanese.)

corrosion

EFFECT

PROPERTIES

to

bonding

(Kawasaki Steel

to result in

service lives of components.

It is

MAGNETS Y. Fukuda, M. Shimotomai

by a balance

to use is reported

increased

China).

13, No 5,

materials as well as forming tools and in wear resistant applications. Matching

IRON-NEODYMIUM-BORON

0. Tong et al. (Academy

Vol

between hardness and toughness. The materials are used for cutting a wide range of metallic and non-metallic

MICROSTRUCTURE AND HARD MAGNETIC PROPERTIES OF ATOMIZED POWDER

Materials,

by addition of VC. Grain growth in the solid state is considered. Discontinuous grain growth in ultraline materials is noted. It is suggested that there is a lower limit of ZOO-300 nm for the grain size of WC and that finer sizes can only be attained by completely new technology.

Methods reviewed

of and

It is suggested a lower limit to

reduced by increased

reaction

liressrii~(~.