The influence of DLC coating on the mechanical and frictional properties of unpeened and peened Cu-based bimetal under dry sliding conditions

In this study, the influence of a combination of high-frequency ultrasonic peening (HFUP) technique and diamond-like carbon (DLC) coating on the mechanical and frictional properties of Cu-based alloy sintered on steel by a powder metallurgy (P/M) technique was investigated. The frictional behavior of the Cu-based alloy specimens was assessed using a Schwingung Reibung Verschleiss (SRV) pin-on-disk tribometer sliding against a Cr-plated bearing steel pin under dry sliding conditions. The purpose of this study is to develop a thin wear resistant layer for Cu-based alloy and to extend its application in the automotive industry. Results showed that the over-coated DLC coating deposited onto a peened Cu-based alloy specimen had higher mechanical and lower frictional properties compared to that of the over-coated DLC coating deposited onto an unpeened Cu-based alloy specimen, which may be ascribed to the undulated microstructure caused by HFUP technique resulting in good adhesion. It was revealed that the deposited DLC coating was beneficial for improving the mechanical and frictional properties of Cu-based alloy. Hence, it is expected that the results of this investigation can be applied to improve the frictional behavior of an internal combustion engine (ICE) components which are made of bimetals (sintered Cu-based alloy on a steel back).