WC-Co cutting tool surface modifications induced by pulsed laser treatment

Many innovative industrial materials like carbon fibers, metal matrix composites (MMC), hypereutectic Al/Si alloys are very hard and difficult to machine with traditional cutting tools. CVD diamond coated inserts seem to be the most promising system to overcome the problem. The WC.xCo hard metal. a widespread used and cheaper bulk material, could be a convenient substrate for diamond film coatings. The Go-rich binder phase, however, constitutes a severe obstacle for diamond deposition and adhesion, owing to its catalytic effect for amorphous carbon or soot formation. Several chemical and physical methods have been developed to etch Co from the surface: however, no definite and reliable procedure has been achieved. In our experiments, we treated the WC.xCo hard metal substrates with ArF(lambda = 193 nm, hv = 6.4 eV) and CO(2) (lambda = 10.6 mu m, hv = 0.12 eV) pulsed lasers, at different fluences and incident angles, to modify both the chemical composition and the structure of the surfaces. The morphological and chemical effects have been studied by SEM/EDAX microscopy and XPS surface analysis. Diamond nucleation and adhesion are compared with results obtained on the: plain tool substrates.