The effect of surface roughness of the substrate on fatigue life of coated aluminum alloy by micro-arc oxidation

In the present work, ceramic coatings are deposited on the surface of 2024-T3 aluminum (Al) alloy by micro-arc oxidation (MAO). The Surface roughness of the Al alloy substrate is different in the range from 0.2 mu m to 1.6 mu m. This paper investigates the effect of surface roughness of the Al alloy substrate and surface treatment on the fatigue properties of 2024-T3 Al alloy. The morphology, microstructure, and phase composition of the oxide layers are examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Surface roughness of the coatings was measured using a 3D measuring laser microscope. The fatigue life of the Al alloy is evaluated under high and low cyclic stress. The results of the investigation have shown that the fatigue life of the coated samples with Ra = 0.2 mu m is higher than others. The fatigue life of coated samples with Ra = 0.8 mu m is very close to that with Ra = 1.6 mu m under high cycle fatigue conditions. The reason is that the roughness of the interface between substrate and coating affects the fatigue life of coated samples. In contrast, the fatigue property changes when the coated samples were applied to high alternating stress. The fatigue performance of the coated Al alloy with Ra = 0.8 mu m is the worst, followed with Ra = 1.6 mu m. The rougher surface and the concentrating distribution of hills and valleys lead to this result. (C) 2018 Elsevier B.V. All rights reserved.