The growth and interface characteristics of diamond films on cemented carbide substrates

Growth characteristics and interface structures of diamond films on cemented carbide substrates synthesised by D.C. plasma jet CVD have been investigated to obtain better understanding of characteristics of diamond growth and diamond/substrate interface, and to improve the adhesion between the diamond films and cemented carbide substrates. The diamond films were characterized by Raman spectroscopy, SEM and indentation test. It is found that content of diamond in the films is greatly affected by the methane concentration in hydrogen. The cross-sections of diamond films show that diamond films grow in a columnar structure. The observation of interface sides of diamond films reveals that interface sides are uneven, and column bases are separated by holes. The results of indentation test suggest that the diamond films with high purity, proper film thickness and proper surface treatment exhibit high adherence to cemented carbide substrates. Even under a load of 150 kgf in indentation test, some films do not crack.