Влияние условий электроосаждения никеля на физико-химические и коррозионные свойства покрытий

Abstract

Galvanic coating of steel products is one of the main methods of corrosion protection, and nickel is one of the most common metals used in the process. Nickel-based electrochemical coatings are widely used as corrosion-resistant and protective coatings. This study focuses on the investigation of formation of nickel-based galvanic coatings under various conditions: at different temperatures, current densities, and using various mixing methods. The coatings were produced by the process of galvanostatic deposition using Watts nickel electrolyte. The effects of the conditions of electrodeposition process on the characteristics and the corrosion resistivity of the resulting coatings were studied. By using optical microscopy, a relation between the electrolysis conditions and the surface morphology or the size of the growing nickel crystals was discovered. It was established that increase of current density increases the microhardness of the coatings, due to the formation of coarse-grained nickel deposits. Highest corrosion resistivity is achieved by creating finely-grained nickel coatings, which are formed under low current density, low temperature and with mechanical mixing. The optimal conditions for producing high quality nickel coatings were established as follows: current density of 25 mA/cm 2 , temperature 20 o C, and using mechanical stirring. The nickel coatings, deposited under these conditions, have a high quality and the process of electrodeposition of nickel characterized by a high current efficiency.