Microstructure, mechanical and wear resistance properties of low-pressure cold-sprayed Al-7 Mg/Al2O3 and Al-10 Mg/Al2O3 composite coatings

Abstract

Aluminium alloy-based metal matrix composites have successfully provided effective wear resistance and repair solutions in the automotive and aerospace sectors; however, the design and manufacture of these alloys are still under development. In this study, the microstructure, mechanical properties and wear resistance of low-pressure cold-sprayed Al-7 Mg/Al2O3 and Al-10 Mg/Al2O3 composite coatings were investigated. The specific wear rates of the coatings were measured when testing them against alumina (Al2O3) counterbody, and the results showed that the cold-sprayed Al-10 Mg/Al2O3 composite coating showed less wear due to its superior hardness, lower porosity and shorter mean free path compared to the Al-7 Mg/Al2O3 composite coating. The microstructural analysis of the worn surfaces of the composite coatings revealed abrasive wear as the primary wear mechanism, and more damages were observed on Al-7 Mg/Al2O3 composite coatings. Most notably, Al2O3 particles were pulled out from the coating and were entrapped between the Al2O3 counterbody and the coating contact surfaces, resulting in a three-body abrasion mode.