Nanocrystalline diamond coating of silicon nitride ceramics by microwave plasma-assisted CVD

The present study reports for the first time NCD coating of Si3N4 substrates by microwave plasma-assisted chemical vapour deposition (MPACVD) using Ar/H2/CH4 gas mixture and varying the substrate temperature (650-1050 °C) and deposition time. Optimal deposition conditions result in growth rates up to 3.0 μm h−1 that allowed the production of continuous NCD films with low roughness (Ra≈22 nm) and grain size of about 10 nm at the lower temperatures and longer deposition times.