Steam pressure and velocity effects on high temperature silicon carbide oxidation

The effects of steam pressure, velocity, and composition on SiC oxidation kinetics were studied. Pressure effects were tested at 1200 degrees C from 0.1 to 1.4 MPa at a steam velocity of 0.25 cm/s. Velocity effects were tested in two furnaces at 0.45 MPa, 1200 degrees C and 0.1 MPa, 1600 degrees C with velocities ranging from 0.25 to 137 cm/s. Steam composition was altered by changing the reaction vessel material. Oxide morphology and composition were determined using optical and electron microscopy, and X-ray diffraction. Porous oxides were observed whenever structural SiC from the reaction vessel saturated the steam with volatilized silica, H-2, and CO. Oxidation kinetics were calculated by the change in SiC thickness. The steam velocity/recession rate followed a power-law relationship of similar to 0.35 while the steam pressure/recession rate followed a power-law relationship of similar to 1.78.