Degradation of aluminum metal matrix composites in salt water and its control

Alloy Al 6013-20 Si in tempers 0, F and T4 showed good resistance to corrosion in salt spray tests. The corrosion rate of the alloy decreased with increased exposure time due to the formation of bochmite (AlO - OH), Studies conducted in 3.5 wt.%. NaCl solution containing suspended particles of polystyrene showed a linear increase in the erosion-corrosion rate with velocity. The localized attack was concentrated mainly on the Al 6013/SiC interface. A high dislocation density was observed at the Al 6013/SiC interface, which interfered with the formation of a homogeneous protective film of bochmite on the alloy surface. Addition of cerium chloride drastically suppressed the rate of corrosion. Sodium molybdate offered a lesser degree of protection compared to cerium chloride. (C) 2002 Elsevier Science Ltd. All rights reserved.