Ni-Ni3B composite coating

Abstract

The paper compares the microstructure and tribotechnical characteristics of composite coatings of 70 wt.% Ni-20 wt.% Cr-5 wt.% Si-5 wt.% B. These coatings are produced by slip casting and unidirectional solidification. The coating composition is substantiated and coating restructuring mechanisms in the forming process are discussed. Natural composite Ni-Ni3B forms the basis of the coating. The fine lamellar eutectic, which occupies ∼50.5% of the coating, consists of Ni3B, a nickel solid solution doped with chrome and silicon, and CrB crystals. The microhardness of the coating and phase constituents are determined. The method of contact eutectic vacuum melting with controlled cooling permits obtaining the nonporous coating without slag inclusions and with homogeneous oriented structure. The mechanism of 3 to 5 times increase in the wear resistance of homogeneous nonporous coatings and their potential application in friction units of machinery are discussed.