| Abstract Scope |
Silicon carbide ceramic matrix composites (SiC CMC) are proposed for use as high-temperature aeroturbine components. In this application, SiC CMCs experience peak temperatures of 1300ºC but degrade more rapidly between 600 and 800°C. Oxidation of SiC CMCs with boron nitride fiber interphase coatings form silica, boria, and borosilicates. Thermogravimetric analysis was used to study SiC CMCs in a flowing oxygen environment for 1- and 50-hours at 600, 700, and 800°C. SEM/EDS was used to characterize the composite before and after oxidation. Inductively coupled plasma optical emission spectroscopy was used to accurately quantify the borosilicate glass composition. At 600°C, boria and borosilicates formed but silica formation was negligible. At 700°C, the lowest oxidation rate was observed as boria volatilized but silica formation was minimal. By 800°C, although boria volatilization was rapid, silica formation was measurable leading to higher weight gain. Understanding these oxidation rates can drive design choices for SiC CMCs. |