Corrosion of SiC monofilament/Ti-15-3-3-3 metal-matrix composites in 3.15 wt.% NaCl

The corrosion behavior of silicon carbide monofilament/Ti-15-3-3-3 (SiC MF/Ti-15-3) metal-matrix composites (MMCs) were examined in 3.15 wt.% NaCl solutions at 30 °C. Electrochemical experiments were conducted on monolithic ultrapure Ti, Ti-15-3 alloy, hot-pressed SiC, SiC monofilament and the SiC/Ti-15-3 MMC to identify the degradation mechanisms that operate in the SiC/Ti-15-3 MMC. At oxidizing potentials, the Ti-15-3 matrix passivated, whereas the carbon cores and carbon-rich surfaces of the SiC MFs were severely damaged. The anodic polarization curve of the actual MMC and a curve generated using the mixed-potential theory were compared. The curves were very similar, indicating that MMC processing did not significantly affect the electrochemical dissolution behavior of the MMC constituents. Galvanic corrosion between the SiC monofilament and Ti-15-3 matrix metal was negligible. The MMC had excellent corrosion resistance in the open-circuit condition.