INFLUENCE OF MICROSTRUCTURE ON MECHANICAL PROPERTIES OF Ni-Cr THERMAL SPRAY COATING OF CRANK-SHAFT IN MARINE ENGINES

Abstract

This article presents about influence of microstructure on the mechanical properties of Ni-Cr thermal spray coating on C45 steel applied for reparing the crankshaft of marine engines. The research results show that: Before heat treatment, the microstructure of the coating has separation compared to the base metal. After heat treatment by full annealing, there were diffusion and formation of a bond layer between the matrix and coating layer. It is this changing about microstructure that affects the mechanical properties of the coating, resulting to improve the effectiveness of maintenance of marine engine’s crankshaft. The hardness value of the coating increases up to 300HV; the adhesion of the coating is up to approximately 30MPa; the value of wearing is reduced to about 1.1,10⁹kg/N.m