ADHESION IMPROVEMENT OF DIAMOND FILMS ON STEEL SUBSTRATES USING CHROMIUM NITRIDE INTERLAYERS

Direct deposition of diamond on ferrous materials suffers from adhesio n problems due to the build up of a graphitic layer at the interface. A successful solution to this problem was attained through the use of an intermediate layer consisting of 20 mu m thick nitrided chromium fi lm. The initial stage of diamond deposition resulted in the partial ca rburization of the chromium nitride interlayer onto which a continuous diamond film was deposited. The adhesion of the diamond film to the s ubstrate was enhanced by complicated mechanical building and chemical bonding of the interfacial region and was measured by an indentation t est. No delamination events occurred during indentation up to loads of 1000 N. Phase transformation into the interlayer, diamond particle de nsity and quality of obtained films were studied for different times o f deposition. The samples were examined by a number of complementary t echniques: AES, XRD, Raman Spectroscopy, SEM and EDS. Residual stresse s in deposited films were calculated from the shift of the diamond pea k in the Raman spectrum and were compared to thermal stresses resultin g from mismatch of the thermal expansion coefficients of diamond and t he substrate. It is suggested that a chromium nitride interlayer could be employed in the deposition of diamond. films on iron based alloys for industrial purposes. (C) 1997 Elsevier Science S.A.