Nanocrystalline electrochemical composite coatings with nickel matrix and boron

Abstract

The possibilities of producing a wear and corrosion resistant nanocrystalline composite coatings with a nickel matrix have been investigated. A Watts type nickel plating bath with low concentration of nickel ions (0·75 mol dm–3), organic addition agents and boron as dispersed particles were used for deposition of the nanocrystalline composite electrochemical coatings. The crystalline growth and preferred orientation of the prepared deposits were studied by X-ray analysis. The content of particles in coatings was examined gravimetrically. The roughness, microhardness and the wear of the coatings Ni–B were measured. Voltammetry was used for examination of the corrosion resistance of samples of composite coatings in 0·5M NaCl. The results suggest that the effect used of the organic compounds was the development of the nanostructure of the nickel matrix. The wear resistance increased with increasing microhardness of deposits. Strengthening the nanocrystalline nickel matrix with boron particles gave a positive effect in the form of high wear resistance. All of the Ni–B composite layers had better corrosion resistance than the nickel coating, which had a microcrystalline structure.