Research on Microstructure and Tribological Properties of the Cp/AlSn Coatings Deposited by Magnetron Sputtering

Abstract

The influences of microstructure and tribological properties of Cp/AlSn (Cp: carbon particule) composite films were applied to AlZn4.5Mg bearing alloy substrates using the closed-field unbalanced magnetron sputtering ion plating technique. The microstructure, phases and bond states of the coatings were separately characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The friction coefficients were measured using a pin-on-disc set-up. Results showed that the grain size and roughness of the films both decreased with increasing of carbon target current (IC) from 0.2 A to 0.8 A. Phases in the films were Al, Sn and C, although the films transformed from a crystalline state to amorphous when the carbon target current was applied. Al and Sn existed as pure metals. Carbon, composed of sp2and sp3bonds, mainly as sp2bonds, provided transfer films to reduce the friction coefficient of the films from 0.35 to 0.15. The specific wear ratio was a minimum, when the carbon target current was 0.4 A.