Determination of the active-to-passive transition in the oxidation of silicon carbide in standard and microwave-excited air

The active-to-passive transition is determined on sintered silcon carbide for two atmospheres: standard air and air excited by micrwaves, as a function of oxygen partial pressure and temperature. The experiments were done at low total pressure ranging from 10(3) to 25 x 10(3) Pa and at high temperature from 1385 to 1765 degrees C at a constant air flow rate. The results are compared with literature data and we try to explain why they are so many differences between all the experimental and theoretical results.