The influence of brighteners on the friction and wear of electrodeposited multilayer films

Abstract

Electrodeposited Cu/Ni multilayer alloy films were prepared on a beryllium bronze substrate by a single bath technique. The tribological behavior of the films was investigated with a DF-PM apparatus which is capable of measuring both the static and kinetic friction coefficients. The effect of the concentration of brighteners on the tribological behavior of Cu/Ni multilayer films was also examined using the same friction and wear apparatus. The surface roughness, crystal orientation, and stress of Cu/Ni multilayers were analyzed with emphasis on revealing the relationship between the structure of the films and their tribological behavior. The results showed that the electrodeposited Cu/Ni multilayer film obtained from the bath containing 0.5 ml l −1 brightener exhibited a low friction coefficient and excellent anti-wear properties. The microstructural observation of the films indicated that highly compact and smooth multilayers were obtained in this case. The results from X-ray diffractometer analysis showed that the orientation of Cu/Ni multilayer films changed from the (200) plane to the (111) plane which is parallel to the surface when the content of the brighteners in the bath increased from 0 to 0.5 ml l −1. Moreover, multilayers with a low level of compressive stress were obtained at a brightener concentration of 0.5 ml l −1. It was supposed that the compactness and smoothness of the Cu/Ni multilayer films, the change in the crystal orientation of the Cu/Ni multilayer films from the (200) plane to the (111) plane, and the low compressive stress of the films jointly contributed to the low friction coefficient and excellent anti-wear properties.