Increasing the Fatigue Strength of Aluminum Alloy Parts UsingComposite Coatings for Aerospace Engineering

Abstract

Aluminum alloys are widely used in many arears of engineering including aerospace engineering. Unfortunately, fatigue properties of aluminium alloys are not sufficient and their increase is very important scientific and practical task. The article is devoted to the studies of the Al2O3  composite coatings’ effect on bending fatigue tests of aluminium specimens. Initially, the coatings were formed by converting the surface of aluminum alloy specimens by anodiccathodic microarc treatment to a depth of 90-110 microns. Then the resulting coating was cladded with a “Cr-CrC” surface layer of 9-14 microns’ thickness from the vapor phase. The clad layer filled the pores and cracks of the Al2O3  coating that formed after the microarc treatment. Based on the analysis of bending fatigue tests results, it is shown that the formed composite layer can be used as a reinforcing coating in aerospace engineering. The effectiveness of the developed coating depends on the part’s section thickness and the level of its loading. In the case under consideration, with cyclic bending stresses of less than 95 MPa, the increase in fatigue strength was 1.75-1.8 times.