PRODUCTION OF CUTTING TOOL MADE OF DIAMOND-COATED TUNGSTEN CARBIDE-BASED SINTERED HARD ALLOY

摘要

PURPOSE:To increase the diamond deposit forming velocity by reducing the Co content in a sintered hard alloy substrate to be coated with diamond, and uniformly dispersing Co in the substrate. CONSTITUTION:Powdery WC, Co, and C are mixed in a specified ratio under ordinary conditions to obtain raw powder, and the raw powder is compacted into a green compact. The green compact is primarily sintered in vacuum at 1400-1500 deg.C. Hot hydrostatic press is applied on the primarily sintered compact at 1300-1500 deg.C and 100-1000 atm pressure to eliminate bores. The pressed compact is secondarily sintered in vacuum at 1400-1500 deg.C to uniformly disperse the Co phase. Consequently, a sintered band alloy substrate consisting of 0.1-1% Co, a trace amt. of finely and uniformly dispersed free C corresponding to C01-C08 of the ISO standard, and the balance WC and having =99% theoretical density ratio is obtained. An artificial diamond coating layer is formed on the surface of the substrate by low-pressure vapor phase synthesis.