Oxidation Behavior of Chemically Vapor-Deposited Silicon Carbide

Active to passive transition in the oxidation of silicon carbide at high temperature and low pressure in molecular and atomic oxygen

“…Just at the transition, Equilibrium 20 is also valid (6) SiC(s) + 3/202(g ) ~--SiO2(s ) + CO(g) AG o (20) (7) with…”

Oxidation behaviour of SiC/SiC ceramic matrix composites in air

“…However, the oxidation rates of CVD SiC were higher than those of sintered SiC due to the presence of free silicon. Schiroky [7] studied oxidation behaviour of CVD SiC at 1200-1800 • C. At >1500 • C, growth of uniform films of amorphous silica was observed and with bubble formation between 1700 and 1800 • C due to the high CO pressure at SiC-SiO 2 interfaces. Oxidation of CVD SiC was also investigated by Narushima et al [8] at 1550-1700 • C. They observed that the parabolic oxidation behaviour of CVD SiC consists of stage I and stage II as a result of a change in diffusion rate of oxygen in the SiO 2 film due to crystallization from amorphous silica to ␤-cristobalite.…”

Blowing of silica microforms on silicon carbide

“…We present results of a phenomenon that we term ÔmicroblowingÕ, where the SiO 2 scale produced by the oxidation of SiC is blown into complex shapes in a similar way to conventional glass blowing techniques. To the best of our knowledge, only simple bubbles have been previously reported e.g., [11,[21][22][23].…”

“…Silicon carbide based ceramics are known to be inherently unstable in oxidizing atmospheres, although they can exhibit oxidation resistance by the formation of a thin, dense and self healing protective silica film at the gas-solid interface [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The oxidation process is well established as being initially rapid [2,3] with a brief (<1 h) linear region, followed by a parabolic region slowing down noticeably with progress of passive oxidation.…”