Wear resistance of nanocrystalline composite NI-B coatings

Abstract

The nanocrystalline composite electrochemical coatings prepared with nickel matrix and boron particles were investigated. Nickel plating bath of low nickel ion concentration (0.76 mol/dm 3) with brightening organic compound, surfactants and dispersed boron particles content was used for coatings electrodeposition. Boron particles content was determined gravimetrically. The dependence of boron content in composite Ni-B coatings on the concentration and kind of the organic additives was investigated. The coatings structure was established using TEM. The microhardness of the deposited layers was measured by Vickers' method at the load of 0.01 and 0.05 kg. The wear experiments of Ni-B coatings were made without lubrication using the technique based on measuring system comprising a flat surface and a ball. On the basis of measurements of wear traces diameter, the wear depth was calculated and assumed as a measure of wear resistance. Tribological properties were investigated using the disc-block measuring system. Friction tests were made on Amsler A-135 machine. The obtained results suggest that the organic compounds used in the experiments had a significant effect on the increase of boron content in coating and the development of nanostructure of nickel matrix.