Some corrosion characteristics of aluminium-mica particulate composites

Abstract

The corrosion behaviour of cast Al-2% Mg, Al-2% Mg-3.5% mica and Al-4% Cu-1.5% Mg-2.5% mica in non-deaerated 3.5% NaCl solution, under simple immersion, erosion-corrosion and corrosive wear conditions was evaluated using weight-loss measurements, electrochemical techniques and scanning electron microscopy. The composites were found to corrode faster than the matrix alloys under all the conditions studied. This was attributed to the mica particles preventing the formation of a continuous passive film and providing sites for pitting and crevice corrosion. Under erosion-corrosion and corrosive wear conditions, the mica particles easily debond from the matrix and cause weakening of the alloy. The corrosion resistance of the materials was found to be in decreasing order: Al-2% Mg > Al-2% Mg-3.5% mica > Al-4% Cu 1.5% Mg-2.5% mica. © 1989.