No 6, 1993-1994, 357-368. The waste products, and their potential environmental impact, associated with the production of ammonium paratungstate, are reviewed. Steps to minimize environmental damage, and to recover valuable materials from waste are out,lined both in respect of AJ’I and other scrap byproducts of W manufacture and processing. DISSOLUTION OF MOLYBDENUM MANDREL WIRE FROM TUNGSTEN FILAMENTS K.Vadasdi et al (Hungarian Academy of Sciences, Budapest, Hungary) Int. J. Refractory Metals & Hard Materials, Vol 12, No 6, 1993-1994, 369-377. The chemistry of dissolution of MO mandrel wire, used in making W lamp filaments, is outlined and attention is drawn to possible environmental problems arising from the use of nitric/sulphuric acid mixtures. A novel method of dissolving Mo in presence of W, using H peroxide, is described. MO is recovered and environmental pollution is minimized.
COATING AND FIBRE EFFECTS IN SILICON CARBIDE REINFORCED TITANIUM F.H. Frees. (University of Idaho, Moscow, Idaho, IJSA) Jvwnal of Metals, Vol 46, No 11, 1994, 62-67. The state of the art of continuous fibre reinforced Ti alloy composites is reviewed. A new method for coating tibres, which enhances the behaviour of Ti/SiC tibre metal matrix composites is described.
Composite SPRAY FORMING COMPOSITES
materials OF METAL MATRIX
A. Lawley, D. Apelian (Drexel liniversity, Philadelphia, IJSA) Powder Metwlluryy, Vol 37, No 2, 1994, 123-128. Spray forming, a hybrid PM process, is discussed and it is noted that in spray forming intcbrfacial properties are not compromized and there is no need to handle fine metal powders. Modification to the Osprey process of spray forming to produce discontinuously reinforced metal matrix composites, reactive and inert techniques, are outlined with respect to the mechanisms involved.
Electrical and magnetic materials EFFECTOFLEADCONTENTON STRUCTURE AND PROPERTIES OF LEAD BASED CERAMIC DIELECTRICS M.Kosec et al (Inst. ‘Josef Stefan’, Ijub,jiana,
Slovenia) Scierrcr f!f Sitctrriny, Vol 26, No 1, 21-27. Studies of La doped sintered I’bOPbTiO:j-PbZrO:I ceramic dielectrics are described. Structures are correlated with the phase diagram. It is reported that the dielectric constants depend on the Ti:Zr ratio which is infiuenced by t.ht concentration of PbO.
Hard materials and tool steels INCLUSIONS DIAMONDS L. Varga Budapest,
et al (Technical llnivcrsity 01 Budapest, Hungary) Iv/t. .I.
Vol 12, No 6, 1993-1994, 349-355. The formation of inclusions in synthetic diamonds is discussed with retilrencc to the effects of high pressures and tempcraturrs. A relationship between parameter changes and the morphology of the inclusions is demonstrated. PROPERTIES BINDERLESS
OF ULTRAFINE GRAIN CEMENTED CARBIDE
been made by vaccuum si ntc%ring at 1440 C followed by HII’. Loss 01’ Al by volatilization is repotlrd. The st ruct urcs aye shown to bc I’in (b with fctw pores. Transvrrsc rupt urc st rongt h ol 1.8 Gl’a and Korkwrll hardncbss of %%A arc’ reported. TRIBOLOGY OF BORON CARBIDETITANIUM BORIDE CERAMICS AND MOLYBDENUM-IRONBORON CERMETS S. Ozaki ct. al (Toyo Kohan Ltd, Ilagashtoyoi Kudamatsu, .Japan) .J..Jtcptr~/ SOC.. Powdw ctnd I’owdr~r MotcL//tfI:%(/, Vol 4 I, No I, 1994, 22.26. (In .Japancscb). Friction and wear charactc>ristics 01’I%,(‘Tiz ceramic and Mo~Frl%~-Fc c(~rmcl materials wrrc invc*stigated. Th(* materials showcbd tow coc~ffic~it~nts ot frict.ion and wear ratcbs up to X00 (‘. This was attributcxd lo t tic\ lubricating cff+cts of oxidr lilms. STRUCTURES AND PROPERTIES OF TITANIUM-TITANIUM CARBIDE HARDMETALS WITH ALLOY ADDITIONS
S. 1masat.o et al (Nippon Tungsten (:o, Fukuoka, .Japan) lVQ?p(~rc 7hgsten Rrw., Vol 26, 1994, 9-20. It is reported that sintered WC:J’%Ti(:21%,TaCwithout binder has low strength. Effects of initial powder particle size on strength and sintering characteristics wer(’ investigated. The required sintering temperature is reduced by small partick% size. Addition of grain growth inhibitors, (:r or V carbides . , rcsultcd in increased hardness, up to Rockwell hardness 95.5A, and bend strergth. Tht* strurturc is shown to consist of fine and uniform carbides.
K. Tokumoto (tt al (Nippon Tungstc>n Co, Fukuoka. .JaJ)an) .J..Jtrptr I( SK. J’owdcr w,d J’owdn~’ M~~trclltryJ,/J.b’ot 4 l, No l, 1994, 27.:J2. (In .Japanc>sc\). I’ropc~rtit~s and srrrc.1 ur(>s of ‘I’i8.4~01% (Cr, MO or W) -47’:,‘l’i(: w(‘r(’ invcstigatcd. Thr phascbs wer(’ ti)und in Tim (:r-Tic: wcr(l TiC, r and p Ti. ‘I&) phascss wcrc obscxrvc>d in Ti-Mo-Tic:, Tic: and aTi. The> alloy with W containc>tl thrc,c> phases, Tic:, BTi and W. The> grain sizcb 01 thr alloy with W was linc>r I harl I ho alloys with (:r or MO and I hcb bc*ntl strcqlh ant1 hardness wcr(’ hightbr.
EFFECTS OF SUBSTRATE ON PROPERTIES OF COATINGS ON CEMENTED CARBIDES
PRODUCTION OF DIAMOND ABRASIVE TOOLS BY EXTRUSIONN
A. Fukawa (Toshiba Tungaloy (:o J,td, Kawasaki, Japan) .J.~Japm SOC. J’owdw and Powder Metc~llury~, Vol 4 1, No I, 1994, (In .Japanese). A study of the effects of t.h(l ccxmcntcd carhidc substrates on the properties of chemically vapour dcpositcd (coatings is described. The imJ)rovcmcnts in cutting performance due to the coatings is correlated with the structures of the suhstratcs.
V. Manukydn (%tal (Armc,nian l’ol.ytylt~chnic. Insl, Tcbrcxvan, Armenia) Sr-ir),rtr.c,f!/’ Sirttvrin!/, vol 26, No l, 1994, 2!)&:J(i. It is reportctl 1hat rnc’tal bontl(~tl diamond lools c’an bc made t1.v(-xl rusion. st rucl ur(bs and propc>rt i(ss, t’rocessing, much high(>r than I’or hot pr”ss”d malctrials, arc’ tl(~scribc~tl. EXPLOSIVE PROCESING SPEED STEEL
Z.Z. Xi0 (\I al. (Ilnivcbrsily of S(+nc,c, and Tochnolom. Ikijing, (China.) .J. I lniversity of Scic,nc.c> and Tc~chnolo~y 01’ tkbijing, No 67, IRR:J, lO~l:l. (In (:hincse). K. Kobayashi rt al (National Industrial An invcbstigation of cbxplosivt> sintcbring Research Inst, Nagoya, .Japan) ,J..JuJNL~/ ol’ two high spcscd stcbc>ts is dcscribcd. I1 SOC. Powder w,d I’owdw M~%ctll~~~J.y. Vol is rc~por’tc~tt that part ial rnc-lting 01 41, No 1. 1994, 14-17. (In .Japancsc). the powdclr occurs at part iclr surl’accts It is reported that W(‘~8,liwt’~:>F‘~~~ 1.4’:~AI t hc c’xlcsnt tlcpc~ntting on I hv cbnc-rgy and WC-(i,7’~,Fc-:).fl’:,Al hardmc~tals had inrpartcsd.
PREPARATION OF HARDMETALS BONDED WITH IRON-ALUMINIUM ALLOY
MPR June 1995