Ion Implantation in WC--Co: Analysis of Treated Surfaces and Testing of Industrial Tools

Conventional microhardness and indentation (scratch) testing have been conducted on cemented tungsten carbide samples implanted with nitrogen ions at 90 keV as a function of ion dose and sample temperature during implantation. The main results obtained are: (a) N implantation can increase the surface hardness up to 40%; (b) the optimum dose lies between 1-3 x 10 exp 17 atoms cm exp --2 for the different grades evaluated, and an excess dose can cause softening; (c) there is little variation with implantation temperature of the hardening effect between 140 and 400 deg C. No hardening is observed at 550 deg C, with a reduced hardness increase obtained at 70 deg C. A programme of industrial trials, considering several different applications of WC--Co tools has been started. In particular, field tests of drills and routers were conducted by a company specializing in a computer-controlled drilling and cutting out of glass fibre/epoxy resin printed circuit boards. Preliminary results are reported, together with microanalysis of the treated surfaces. Graphs, photomicrographs. 14 ref.--AA