EFFECT OF CURING CONDITIONS ON PROPERTIES OF IRON-RESIN M A T E R I A L S F O R LOW F R E Q U E N C Y USES
C.Gelinas et al. (Quebec Metal Powders Ltd, Quebec, Canada.) Production of Fe-resin materials, by blending Fe powder with a thermosetting resin followed by heating to melt the resin, which flows round the Fe particles, was described. The materials were shown to have good dielectro-magnetic properties for pulsed DC and low frequency AC applications and to have low eddy current losses. Properties of Fe-0.8%resin, pressed at 65°C and 13.8 MPa and cured at various temperatures were presented. DEVELOPMENT OF A SOFT M A G N E T I C I R O N . A L U M I N I U M ALLOY FOR AUTOMOTIVE APPLICATIONS
T.Nielson et al. (Williams International, USA.) Materials for soft magnetic applications were discussed with respect to properties and the traditional use of pure Fe, low C steel and Fe-(2 to 3)%Si. It was reported t h a t a soft magnetic alloy, Fe-I%A1, had been developed. This was shown to have high permeability, low coercivity and high saturation magnetization. Effects of process conditions on structure and properties were described.
Crack detection and prevention USE OF RESONANT INSPECTION TO O P T I M I Z E DIE WALL LUBRICATION
R.Nath, P.Bowen. (Gasbarre Products, USA.) Resonant inspection was discussed with reference to use of the technique at all stages from product design d e v e l o p m e n t and process design t h r o u g h to final inspection of parts. The potential for detection of defective parts prior to sintering was reviewed with respect to s u b s e q u e n t detection of defects in sintered products. A practical study, using resonant inspection of green and sintered p a r t s was described. Influence of lubricant was investigated with regard to the effects of reducing the l u b r i c a n t concentration of powders and optimization of die wall lubrication. N O N - D E S T R U C T I V E T E S T I N G OF SUB-SURFACE AND SURFACE B R E A K I N G D E F E C T S IN G R E E N COMPACTS
D.Apelian et al. (Worcester Polytechnic Inst., USA.)
40 MPR March 1999
The importance of non-destructive testing was noted. It was reported that a new electrostatic t e s t device, for green parts, had been developed. A multi-point probe is placed on the test piece and current is injected in different directions. Differences in voltage drop are monitored by an a r r a y of recording contact pins. The device was tested against compacts containing h a r d plastic inserts, to simulate subsurface and surface b r e a k i n g defects. Electrical resistivity was discussed with reference to material compositions and defect sizes. E v a l u a t i o n was against production samples. PM98. The following abstracts are from papers which were presented at t h e 1998 P o w d e r M e t a l l u r g y W o r l d Congress, which was held in G r a n a d a , S p a i n , in O c t o b e r 1998.
Hard materials MEASUREMENT OF FRACTURE T O U G H N E S S O F M I C R O G R A I N E D WC BY TWO M E T H O D S
L.Guerra-Rosa, J.C.Fernandes. (Inst. Superior T~chnico, Portugal.) The need to be able to measure plane strain fracture toughness, Klc, of hard and brittle materials, for inter-material comparison and forensic investigation, was discussed with regard to test methods. An investigation of fracture toughness of micrograined WC-4%Co, in the form of parallelopiped specimens 20 by 6.5 by 6.5 mm in size, too small for most test methods, was described. Indentation and 3point loading bend tests were used and consistent values of K1¢ were obtained. FRACTURE TOUGHNESSMICROSTRUCTURE RELATIONSHIPS IN U L T R A F I N E WC-Co
N.Sacks et al. (University of Cape Town, South Africa.) An investigation of hardness and indentation fracture toughness of fine grained WC-Co, made from various powders, was described. Influences of composition and particle morphologies were evaluated together with the effects of vacuum annealing at 700 to 1000°C. R E L I A B I L I T Y C H A R A C T E R I S T I C S OF HARDMETALS
H.Reshetnyak, J.Kiibarkeep. (Tallinn Technical University, Estonia.) Strength properties and wear resistance of WC-Co and TiC based hardmetals, bonded to steel substrates, were investigated. The materials were used in sheet metal blanking operations. It was shown that standard mechanical properties do not allow estimation of reliability
in metal forming applications. Wear resistance is related to elasto-plastic properties and resistance to brittle fracture, as shown by edge chipping, depends on the ability of both phases to absorb energy by m e a n s of localized plastic strain. For reliability evaluation of hardmetals factors were deduced and described. PERFORMANCE OF CEMENTED C A R B I D E T O O L S IN M A C H I N I N G PRINTED CIRCUIT BOARD
J.Aucote, A.Grearson. (Sandvik Hard Materials, Coventry, UK.) It was reported t h a t the wear of cemented carbide tools, used for cutting printed circuit board, is clue to attack on the Co binder by constituents of the PCB. Tool wear can be minimized by reduction in %Co in the tool and by reduction in the Br content in the PCB. PROPERTIES AND COMPOSITION OF TITANIUM CARBIDE-NIOBIUM CARBIDE CEMENTED CARBIDES
L.Bodrova et al. (Ternopil State Technical University, Ternopil, Ukraine.) Properties and structures of TiCNbC-(Fe-Cr), with nitrides added to inhibit grain growth. Cemented carbides were investigated as functions of composition. Powders were pressed and liquid phase sintered. Alloys were shown to have good oxidation resistance, up to 1000°C, when heated in air. Strength increased with increase in %NbC.
Powder injection moulding I N J E C T I O N M O U L D E D TUNGSTEN H E A V Y ALLOY
Y.Li et al. (PM Research Inst., Changsha, China.) MIM feedstocks of W-2%Ni-l%Fe, with various solids loadings, were prepared to investigate the rheological properties, sintering shrinkage and assintered mechanical properties. The feedstocks were considered as pseudoplastic fluids. Injection moulded and sintered alloys were reported to have better mechanical properties than pressed and sintered materials. The optimum soIids loading was shown to be 47vo1%. Solvent debinding was used and a model for this was presented. NOVEL STAINLESS STEELS FOR INJECTION MOULDING
O.Markus et al. (ETH, Ziirich, Switzerland.) Stainless steels for two applications, first, in medical prostheses where Ni may present allergy problems and second, where higher hardness, above