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The wear resistance of 17-4PH stainless steel was improved at wide temperature (25–200 °C) by depositing multi-layered Cr/CrC/DLC coating. The results showed that the lubricating effect of the transfer layer led to a reduction of the friction coefficient to 0.03. DLC coating had a protective effect on the 17-4PH substrate, and the surface of the coating was basically not worn at 25–100 °C. This study focused on the wear mechanism and frictional chemical reaction mechanism of multi-layered coatings at wide temperatures. With the increase of temperature, the wear mechanism of DLC coating changed from abrasive wear to adhesive wear, and finally delamination. The complex tribochemical reaction in the wear process led to the dynamic change of its graphitization transformation, which affected the formation of the transition layer and the change in surface mechanical properties of the coating. This was mainly because the transition layer Cr/CrC and Si 3 N 4 played a role in inhibiting the graphitization transformation of DLC layer during the wear process, thus affecting the friction properties of DLC. [Display omitted] • The dynamic process of graphitization and the lubrication of the transfer layer lead to COF to 0.03. • The dynamic process of graphitization intensification and inhibition appears. • The graphitization of DLC is inhibited by the transition layer and the counter abrasive materials. [ABSTRACT FROM AUTHOR]

In current work, the wear resistance of CuNiAl was improved by the application of an aromatic thermosetting co-polyester (ATSP)-based coating on its surface. Tribological behaviors of the ATSP coating at stresses of 1.52, 3.04 and 3.75 MPa under different lubrication conditions (dry friction and oil) were studied by the fretting wear test. The morphology and chemical composition of the coating were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and three-dimensional (3D) optical microscope. Results showed that at the same conditions, the friction torque of the ATSP coating was lower than that of CuNiAl. Significantly, wear was reduced by more than 90% after the application of the ATSP coating. The wear mechanism of the ATSP coating was slight deformation with pits induced by plastic deformation and fatigue crack propagation. The ATSP coating underwent molecular chain breakage during wear and chemical reaction with the friction pair to form a transfer film which played an important role in the reduction of wear. • The friction and wear properties of ATSP coating under fretting wear were investigated. • ATSP coating can significantly improve the wear resistance of CuNiAl. • ATSP coatings undergo complex chemical changes during wear。. • Transfer film is an important factor in reducing ATSP friction and wear. [ABSTRACT FROM AUTHOR]