Microwave plasma CVD of diamond films on high concentration alloys: Microstructure, hardness and wear properties

Polycrystal diamond films were synthesized on high concentration alloys (HCAs) by microwave plasma chemical vapour deposition. It was found that the continuous diamond films formed in a short period, e.g., 10 min. The carbides including the stable MC [0 1 1] (M = Mo, Nb, Ta, Ti and Zr) and metastable carbides (e.g., Mo2C, Ti2C and Mo3C2) were identified by X-ray diffraction and transmission electron microscopy. The diamond/carbide interface had an orientation relationship as [0 1 1]Diamond//[0 1 0]Mo2C. The hardness of MoHfNbTaTiZr HCA at the CH4 concentration of 9% for 20 min was as high as 1238.2 HV0.3. The friction coefficient was 0.56-0.73 for the specimens with continuous diamond films. No spallation of films after friction indicated good wear resistance and adhesion.