CORROSION OF SIC MONOFILAMENT TI-15-3-3-3 METAL-MATRIX COMPOSITES IN 3.15 WT.PERCENT NACL/

The corrosion behavior of silicon carbide monofilament/Ti-l5-3-3-3 (Si C MF/Ti-15-3) metal-matrix composites (MMCs) were examined in 3.15 wt. % NaCl solutions at 30 degrees C. Electrochemical experiments were con ducted on monolithic ultrapure Ti, Ti-15-3 alloy, hot-pressed SiC, SiC monofilament and the SiC/Ti-15-3 MMC to identify the degradation mech anisms that operate in the SiC/Ti-15-3 MMC. At oxidizing potentials, t he Ti-15-3 matrix passivated, whereas the carbon cores and carbon-rich surfaces of the SiC MFs were severely damaged. The anodic polarizatio n curve of the actual MMC and a curve generated using the mixed-potent ial theory were compared. The curves were very similar, indicating tha t MMC processing did not significantly affect the electrochemical diss olution behavior of the MMC constituents. Galvanic corrosion between t he SiC monofilament and Ti-15-3 matrix metal was negligible. The MMC h ad excellent corrosion resistance in the open-circuit condition.