Oxidation of SiC in low-pressure CO2 plasma: Formation of silica nano-needles
Résumé
Samples of silicon carbide were exposed to carbon dioxide plasma at high temperature to study thermal and chemical degradation, as well as the evolution of surface morphology. Scanning electron microscope images revealed that the samples remained fairly intact up to a temperature of approximately 1700 K, when surface modification and degradation started to occur. The oxidation at high temperature caused the formation of liquid silica droplets that were several μm in diameter at a temperature exceeding 1800 K. Sharp nano-needles were found that stretched perpendicularly from the surface at this temperature. Increases in temperature resulted in increased density of the droplets with nano-needles until the entire surface was covered with the nano-needles at a temperature of approximately 1850 K. Further increases of temperature caused rapid degradation of material and loss of the nano-needles. These results are explainable by the particularities of passive oxidation of SiC upon treatment with plasma particles.