Corrosion Behavior of Compocasted ZA27/SiCp Composites in Sodium Chloride Solution

The corrosion behavior of particulate ZA27/SiCp composites in an aerated sodium chloride solution was studied. The composites were synthesized via compocasting with addition of 1, 3 and 5 wt.% SiC particles in the matrix alloy. Composite samples were immersed for 30 days in the 3.5 wt.% NaCl solution open to the atmospheric air. Surface appearance and microstructure of the composites were examined by means of optical microscopy and scanning electron microscopy, while corrosion rates of the composites were determined using the weight loss method. It was revealed that SiC particles were not influenced by corrosion. General uniform corrosion occurred in the composite matrices, mainly in the region of the η phase. Local corrosion was noticed in micro-cracks and near clusters of particulate reinforcements. Results of microstructural examinations and immersion test indicate a slightly lower corrosion resistance of the ZA27/SiCp composites compared to that of the matrix alloy.