Abstract: The surface and backside morpologies of diamond thin film as well as the surface morphology of the cobalt cemented tungsten carbide (YG8) insert after
deposited using D. C. plasma jet CVD method were observed by SEM. The cross-sectional morphology and microstructure of a CVD diamond thin film grown onto the cemented carbide insert were studied by means of TEM. Fourier transformated
laser Raman spectrometry was also used to characterize the structure compositions of the diamond thin film deposited and the cemented carbide insert
surface after diamond thin film delaminated. The results show that there exists a thin layer of graphite carbon (tens of nanometers) at the interface of a diamond thin film
coated cemented carbide insert. It has been seen, However, that diamond particles can be grown directly onto WC crystals at partial zones. Typical cross-sectional
morphology of a diamond thin film coated cemented carbide insert formed on the basis of pertreatment processes such as chemically cobalt-removed and plasmaetching
decarbonized treatments is as follows: diamond thin film; graphite carbon thin layer; small WC grains layer, retained decarbonized layer (W and η phases); YG8
cemented carbide substrate.

Key words: diamond thin film, cemented carbide, interface, cross-sectional morphology