Friction-wear behaviours of micro-arc oxidation films in situ grown on 7475 aluminium alloys

An oxide film was prepared on 7475 aluminium alloy using a micro-arc oxidation (MAO). The surface–interface morphologies, chemical compositions and phases of the obtained MAO films were analysed using a field emission scanning electron microscope, energy dispersive spectrometer and X-ray diffractometer, respectively, and the friction-wear properties of the MAO film under the different loads and wear speeds were investigated using a wear test. The results show that there are a large number of convexes and concave features on the MAO film, which are primarily composed of Al and O, and the phases of MAO film are composed of α-Al2O3 and γ-Al2O3. The MAO film is in situ produced on the 7475 aluminium alloy, forming a metallurgical bonding with the substrate. The average coefficients of friction (COFs) and wear depths before and after MAO decreased by 40, and 26·5%, respectively. The COFs of MAO films decrease with the wear loads and speeds, while the wear volumes increase with the wear loads and speeds...