Investigation on tribological characteristics of Al 7075 coated with aluminium chromium nitride (AlCrN) by magnetron sputtering

Abstract

Structural components used in aerospace, automotive, and civil applications should have an increased shelf life. Fretting wear occurring in aluminum alloys decreases the reliability of the components. This study presents the investigations of tribological characteristics of Al7075, coated with Aluminium Chromium Nitride (AlCrN) by Physical Vapor Deposition (PVD) magnetron sputtering technique. Although Al7075 possesses a high strength-to-weight ratio, it has inadequate resistance against fretting wear. The experimental findings of the wear test (Pin on Disc) reveals that AlCrN coating on Al7075 increases the wear resistance and exhibits a low coefficient of friction. A thin film coating of AlCrN given on Al7075 enhances its tribological and corrosion properties. The existence of AlCrN coating composition on the substrate is confirmed by the results of Energy Dispersive Spectroscopy (EDX). Crystal structural phase analyzed using X-ray diffraction (XRD) shows Face Centered Cubic (FCC) structure for coated Al7075 samples. The pin-on-disc test results show that the wear rate has reduced for coated samples. A salt spray corrosion test is executed to evaluate the corrosion rate for 24 h. When comparing coated samples to uncoated samples, it is found that the corrosion rate is lower for coated samples. The average hardness value of the coated Al7075 sample is higher than the uncoated ones. The surface roughness of the coated sample is observed to be less than that of uncoated Al7075 samples.