Application of Cr – Ni coatings by chemical-thermal treatment from lowmelting metal solutions

Improving the performance properties of parts and structures, such as corrosion resistance and wear resistance, is an extremely important area of materials science research. Surface alloying with corrosion-resistant elements such as chromium and nickel makes it possible to solve this problem. The work is aimed at obtaining chromium-nickel diffusion coatings on the surface of carbon steels by chemical-thermal treatment from a solution of chromium and nickel in eutectic (Pb-Bi), by subsequent and simultaneous diffusion deposition of chromium and nickel. The eutectic alloy of bismuth and lead with a melting point of 125 °C was chosen as the transport melt. Diffusion saturation with chromium Kh99 and nickel N-1 of samples from carbon steel grades 20, 45 and U8 was carried out. Metallographic analysis was performed, Vickers microhardness measurements were made in order to study the structure, evaluate the character of the obtained coatings and reveal regularities depending on the saturation mode and the processed material. At formation of chromium-nickel coatings on carbon steels in surface layers a carbide layer on the basis of chromium is formed. The hardness of such a layer can be HV1800-2000. The chemical composition of the surface of the treated samples was evaluated by X-ray fluorescence analysis.