Influence of SiC_P content and inhibitor on the corrosion behavior of SiC_P/Al metal matrix composites

The corrosion behavior of ZL101A aluminum alloy and silicon carbide particulate/aluminum (SiC_P/Al) metal matrix composites was studied in a medium of aqueous sodium chloride (NaCl) solution, where the SiC_P/Al composites contained 5vol%, 10vol%, 15vol% and 20vol% SiC_P. Corresponding ZL101A base aluminum alloy was subjected to identical test conditions to study the influence of SiC_P on corrosion characteristics. By means of immersion test at room temperature, sodium molybdate (Na₂MoO₄) and sodium silicate (Na₂SiO₃) were used as inhibitors. Weight loss and scanning electron microscopy (SEM) were used to evaluate the corrosion rate and surface microstructure of the SiC_P/Al metal matrix composites. The results show that average corrosion rate do not vary greatly in relation to the amount of SiC_P reinforcement, even some degree of decrease. Normal pit initiation and propagation were altered by the presence of the SiC_P reinforcement. Pits on the SiC_P/Al composites were significantly more numerous, shallow, and wide spread than on the ZL101A matrix materials. It was found that more effective to prevent the pit initiation on the surface of the SiC_P/Al composites with Na₂MoO₄, Na₂SiO₃. No obvious effectiveness was observed when containing of the SiC_P reinforcement with 15vol% and 20vol% in the SiC_P/Al composites.