Dependence of the diamond coating adhesion on the microstructure of SiC-based substrates

Diamond thin films were deposited on the SiC-30TiC-10Cr(3)C(2) substrates by using the microwave plasma CVD method and the effect of microstructural morphology of substrate was examined on the diamond-substrate adhesion strength. Two types of substrate were prepared by hot-pressing, one with small and equiaxed beta-SiC grains and the other with large and elongated alpha-SiC grains. The SiC-30TiC-10Cr(3)C(2) substrate surfaces were chemically etched to remove (Ti,Cr)C matrix phase by Murakami solution. Better diamond-substrate bonding was obtained on the substrate composed of large, elongated grains. Vickers indentation results indicated that mechanical interlocking between elongated and protruded grains on the etched surface and diamond thin him resulted in an increase in adhesion strength. (C) 1999 Elsevier Science S.A. All rights reserved.