DIAMOND NUCLEATION AND GROWTH ON DIFFERENT CUTTING-TOOL MATERIALS - INFLUENCE OF SUBSTRATE PRETREATMENTS

Diamond coated cutting tools seem to be one of the most promising econ omical and technological applications of the low-pressure diamond depo sition methods. The main problem associated to this application is the nucleation and growth of a uniform diamond deposit with a suitable an d reliable adhesion, withstanding thermal and mechanical stresses, ori ginating by the severe cutting conditions. In this work we have studie d the HF-CVD deposition conditions of diamond on different tool substr ate materials: cer-mets (WC, Co); ceramics (SiAlON, Al2O3 + TiC) and w hisker reinforced ceramics (Al2O3 + SiC and ZrO2). We have examined, b y SEM-EDAX and XPS surface analysis, the influence of chemical, mechan ical and physical substrate pretreatments on the substrate surface mod ification. Strong Co etching and reducing seems to be the best WC, Co substrate pre-treatment for a suitable diamond nucleation and adhesion ; the SiAlON ceramics are very good substrates for high quality diamon d growth. Raman spectroscopy have evidentiated an excellent diamond fi lm quality, with a small energy shift (1337 cm(-1)), may be owing to s ome compressive deformation.