Silicon carbide coating of mullite substrates by the CVD technique

Silicon carbide films were applied on polished and rough mullite substrates by the APCVD technique at 1100, 1200 and 1300 °C, using methyltrichlorosilane as precursor gas. XRD analysis shows that graphite films were deposited on substrates at 1100 °C, and only above 1200 °C were deposited β-SiC films. The crystallinity was found to improve as the deposition temperature increases, and no preferential alignment of the crystal structure was observed. Rough substrates produced dense films while polished substrates produced porous ones. Tests on films produced at 1300 °C revealed microhardness to be 3813 kgf/mm2. Wear tests on films produced under the same conditions showed a mass loss of 0.0029 g/km without film detachment, indicating good adherence of the film to the substrate.