The investigation results of the structure and wear resistance of composite chemical coatings on the nickel base obtained by means of mutual codeposition with nanodispersed particles of aluminum oxide and potassium polytitanate are presented. The investigations are carried out by scanning electron microscope. It is found, that composite nickel penetrates into the base metal to a depth of about 5 µm, forming diffusion layer, which provides an increased cohesive strength of the coating with base metal. Composite coating has abundance of inclusions of different size along the whole surface; which are absent in the base coating. Nanodispersed particles penetrate into the coating; accelerate the nickeling process, which provides the increase of the coating wear resistance.

The article presents the results of research on the establishment of an effective nanoscale phase and modes of applying nanocomposite electroplating coatings based on chromium. As a result of the conducted studies, it was found that it is advisable to use a nanodispersed aluminum oxide powder as a nanoscale phase. The method of mathematical planning of the experiment was used to determine the optimal modes of coating and the concentration of nanoscale particles in the electrolyte. The microhardness of the obtained coatings was chosen as an optimization parameter, since it significantly affects their wear resistance. The highest microhardness of a nanocomposite electrolytic coating based on chromium is achieved when the electrolyte is heated to a temperature of 50 °C, a current density of 59 A/dm2 and a concentration of nanoscale phase particles in the electrolyte of 3.2 g/l, which ultimately corresponds to an increase in microhardness to 14.32 GPa. It is also established that nanocomposition coatings have a positive microhardness gradient in thickness, which allows leveling the difference in the values of the microhardness of the coatings and the base metal and will help to increase the adhesion strength of the coatings to the base on the one hand and their wear resistance on the other. Based on the microhardness measurements of chromium-based nanocomposition coatings, statistical series were formed. 30 samples were subjected to measurements. According to the results of microhardness measurements, the average square deviation of the values of nanocomposition coatings based on chromium was 0.05 (coefficient of variation 0.283). To equalize the obtained experimental microhardness information, the law of normal distribution is chosen, since the coefficient of variation, according to which the greatest probability of microhardness values of nanocomposite coatings based on chromium is observed in the range of 14.32–14.37 GPa.

Предложена физико-математическая модель механизма упрочнения гальванических покрытий наноразмерными материалами. Установлено, что на механизм упрочнения наибольшее влияние оказывают структурные превращения, происходящие в нанокомпозиционных покрытиях. Исходя из физических процессов, происходящих в гальванических покрытиях при модификации их наноразмерными материалами, была обоснована и исследована физико-математическая модель механизма их упрочнения. Представленная модель позволяет прогнозировать степень упрочнения нанокомпозиционных покрытий в зависимости от используемых нанодисперсных материалов и расстояния между ними в покрытии. Рис. 4. Схема конструкции установки для ультразвуковой подготовки зерна к помолу

By adding nanosized materials to electrolytes, coatings with improved physical and mechanical properties can be obtained. Galvanic coatings are used to solve the problems of machine-building and repair production, both in the automotive industry and in construction, aviation, radio and electronic industries. The most interesting were potassium polytitanates. To obtain chromium-based nanocomposite electroplating coatings, the following group of nanosized particles was selected for research: Al2O3, AlN, SiC, TiC, WC, K2OnTiO2. The article considers methods of increasing sedimentation resistance of electrolytes for application of nanocomposite electroplating coatings based on chromium. To obtain chromium-based nanocomposite electroplating coatings, a self-regulating chromium electrolyte was selected. The method of plasma re-condensation is selected, allowing to obtain various nanodisperse materials with particle size from 10 to 100 nm. Studies have shown that electrolyte suspension obtained by ultrasonic generator treatment with frequency of 22 kHz for 10-12 min is most resistant. Coating application should be carried out under constant action of ultrasonic oscillations of ultrasonic bath with frequency of 18 kHz. The microhardness of the coatings obtained by this method, using nano-sized particles Al2O3, reaches 14.1 GPa, which is 1.03... 1.21 times the microhardness of the coatings obtained with other particles and 1.47 times the microhardness of the coatings without adding nano-sized particles.