Study on the Deposition and Characterization of Nanocrystalline Diamond Composite Films

Nanocrystalline diamond composite films were fabricated on the WC-Co substrates using a bias-enhanced hot filament CVD system. Methanol solution pretreatment method for removing the Co in surface of WC-Co substrates was put forward. The composite structure was achieved by regulating the concentration of Ar in a mixture of acetone and a hydrogen gases in different stages. The surface morphologies, nucleation density, diamond films and composition of the nanocrystalline diamond composite films were observed with different techniques. The results showed that the introduction of Ar increased the second nucleation of diamond grains which made the diamond grains finer. Nanocrystallie diamond film can be successfully grown on the microcrystalline diamond films. The two-layer structure has the advantages of good adhesive strength and low surface roughness. Because of nano effects, the hardness of composite films decreases. This is prone to be polished and reduces the work load significantly. It is of great importance for the wide application of diamond films in the precision machining fields.