Diamond nucleation and growth on different cutting tool materials: influence of substrate pre-treatments

Diamond coated cutting tools seem to be one of the most promising economical and technological applications of the low-pressure diamond deposition methods. The main problem associated to this application is the nucleation and growth of a uniform diamond deposit with a suitable and reliable adhesion, withstanding thermal and mechanical stresses, originating by the severe cutting conditions. In this work we have studied the HF-CVD deposition conditions of diamond on different tool substrate materials: cer-mets (WC, Co); ceramics (SiAlON, Al2O3 + TiC) and whisker reinforced ceramics (Al2O3 + SiC and ZrO2). We have examined, by SEM-EDAX and XPS surface analysis, the influence of chemical, mechanical and physical substrate pretreatments on the substrate surface modification. 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 diamond growth. Raman spectroscopy have evidentiated an excellent diamond film quality, with a small energy shift (1337 cm-1), may be owing to some compressive deformation.