Wear Resistance of Nickel Composite Coatings with Micron-Sized and Submicron-Sized Particles of SiC

Introduction. Electrolytic deposition of nanoparticles is gaining interest with their increasing demand for restoring surface layers of machine parts and mechanisms. To create composite coatings with nanoparticles, it is necessary to solve two main tasks: to ensure a sufficient number of particles in the coating and to prevent their agglomeration in the coating solutions.These coatings with nanoparticles are wear-resistant and are used, for example, in automobile and tractor engines. In this study, there are considered the process of electrolytic production of composite coatings based on a nickel matrix with micron-sized and submicron-sized silicon carbide (SiC) particles from Watts nickel solutions and the resistance of nickel composite coatings to sliding wear.Aim of the Study. The study is aimed at considering detailed the effect of the size and number of particles in the coating solution on the number of codeposed particles. It is also necessary to study how the particle size affects the codeposition of micron-sized and submicron-sized particles of the non-Brownian type.Materials and Methods. A conventional nickel-plating electrolyte was used for nickel-based composite coatings with SiC. There was measured particle number density for each coating solution. It was assumed that the particles had the same size and shape of a sphere. The concentration of particles in the coating solutions ranged from 0.28 to 104 g/l. Electrodeposition was carried out on vertical electrodes, and the coating solution was stirred with a magnetic stirrer during electrodeposition. The Vickers microhardness with a load of 30 g was measured and wear tests were performed for unidirectional and bidirectional sliding.Results. The results of studying the wear resistance of nickel composite coatings during sliding have been obtained. The results of codeposition and a model based on the density of codeposed particles are presented. There has been made the conclusion about effect of codeposed particles on the wear resistance of Ni-SiC composite coatings.Discussion and Conclusion. It was determined that the best sliding resistance was obtained using Ni-SiC composite coatings containing 4–5 volume percentage of submicron-sized SiC particles. The study showed that the size and density of SiC particles in the coating solution are important for producing galvanically wear-resistant composite coatings, based on the relationship between the density of deposited particles and the density of particles in solutions.