扁平なCo相を有する超微粒超硬合金の特性

抄録

Mechanical properties of ultra-fine grained cemented carbides with 12wt% Co binder produced by pulsed-electric current sintering were compared with those of cemented carbides by conventional vacuum sintering. The cemented carbides prepared by pulsed-electric current sintering had 6% higher hardness and 23% higher fracture toughness. These excellent properties seemed to be caused by ultra-fine WC grains and flattened Co phase in the sintered compacts. The flattened Co phase tended to be arranged in a perpendicular direction against a pressurized direction during sintering. However the increasing effect of fracture toughness by the flattened Co became small according to decreasing of Co contents. The fracture toughness of the compacts with Co binder less than 2wt% Co sintered by pulsed-electric current process was about 8% smaller than that by conventional process. But the hardness was about 20% higher than that by conventional process. The transverse rapture strength of ultra-fine grained cemented carbides sintered by pulsed-electric current process was about 28% smaller than that by conventional process.