Preparation of silicon carbide and tantalum carbonitride composite with high hardness and moderate elastic modulus by laser chemical vapor deposition for anti-erosion protective coatings

Abstract

Maintaining the harness of silicon carbide (SiC), while reducing Young's modulus of ceramic coatings is crucial for developing highly durable coating systems. This study demonstrated the growth of SiC and tantalum carbonitride (TaCN) composite films with high hardness and low modulus using laser-assisted chemical vapor deposition (CVD) with metal-organic precursors. The effects of deposition temperature on phases, chemical compositions, binding states, microstructures and mechanical properties were investigated. The film prepared at a deposition temperature of 1100 °C were grown at a deposition rate of 81.8 μm h−1, which comprised low-crystallinity SiC and TaCN grains smaller than 10 nm finely mixed and dispersed each other, forming a nanometric mosaic structure. The cross-sectional nanoindentation tests revealed a reduced Young's modulus (E*) of 238.2 GPa and a hardness (H) of 30.4 GPa, corresponding to H/E* and H3/E*2 values of 0.127 and 0.493 GPa, respectively. The SiC–TaCN nanocomposite film exhibited superior durability in erosion tests using a zirconia slurry at 20 kPa, compared with a monolithic SiC film and a silicon nitride substrate.