Modification of silicon carbide coating by ion implantation

Chemical vapor deposition SiC coating was implanted with Al³⁺, B³⁺ and Si⁴⁺, respectively. The effect of ion implantation on sealing cracks in SiC coating was observed by scanning electron microscope, and the phase present in the coating surface was analyzed by X-ray diffraction. Oxidation was conducted in simulated air at 1300°C for 15 h to evaluate the effect of ion implantation on oxidation resistance properties of the coating. Aluminium ion implantation greatly increases the material oxidation resistance, with a decrease of mass loss of about 0.3% of materials without implantation. Though Al³⁺ implantation is favorable for sealing the cracks in the coating, a glassy non-uniform oxide film with several bubbles and holes can be observed. With B³⁺ implantation, the mass loss of the material decreased to about 0.1% of that without implantation. The formed glass oxide film is uniform and has good liquidity, but the air bubbles and holes affect the glass oxide film s ability to seal the cracks of the coating. After oxidation in simulated air for 15 h, the mass loss of materials with Si⁴⁺ implantation stays nearly the same value as that of materials with B³⁺ implantation. However, there is a trend of increase in mass loss with Si⁴⁺ implantation, which indicates that Si⁴⁺ implantation is not favorable for improving the oxidation resistance of the coating.