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.
Highlights
As a result of the current rapid technology innovation and economic development, there has been an increase in the demand for lightweight Al alloys with superior mechanical properties in critical industrial sectors such as aerospace and automotive
The concentration of Al2O3 ceramic particles retained in the composite coatings AMC7 and AMC10 shows a negligible difference; comparing the concentration of A l2O3 in the feedstock powder blends and in the composite coatings, a difference emerges suggesting a change in their deposition efficiency
The higher amount of the Mg in the Al–Mg alloy further improved the microstructure of the coatings, as the porosity of AMC10 reduced by ~ 70% compared to AMC7, with the underlying mechanisms needing further investigation
Summary
As a result of the current rapid technology innovation and economic development, there has been an increase in the demand for lightweight Al alloys with superior mechanical properties in critical industrial sectors such as aerospace and automotive. The fabrication of protective metal matrix composite (MMC) coatings on Al alloys is an effective way to produce high-performance materials as required in these sectors. MMC coatings combine the properties of a ductile metallic matrix and the high strength of a reinforcement phase for a specific performance [1]. The size, weight fraction and distribution of the reinforcement. Coventry CV1 5FB, UK particles and the interfacial bonding between the matrix and reinforcement predominately determine the properties of MMC coatings [5]. A higher weight fraction of reinforcement particles and a shorter mean free path between these particles improve the load sharing capacity, hardness and resistance to wear [6]
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