Study of influence of plasma spray conditions on the mechanical properties of Ni-50%Cr coatings

The influence of plasma spray parameters on the mechanical properties of plasma sprayed N-50% Cr coatings were studied systematically by the orthogonal regression experimental design method. The properties include adhesive strength, microhardness, abrasive wear and erosion wear. The three spray parameters used as variables are plasma arc current, Ar flow and spray distance. The relationships between the properties and the three spray parameters are as follows: With the increase in spray distance, the coating hardness is increased and the wear resistance including abrasive wear and erosion wear are improved. The argon flow influences the adhesive strength significantly. With the increase in argon flow, the adhesive strength of the coating is decreased, while the microhardness and abrasive wear resistance tends to be increased. The influence of arc current and argon flow on the abrasive wear resistance presents a contrary tendency to that of the erosion resistance. It can be considered that such a difference results from the preferred deposition of oxides along lamellar interfaces and from the different wear mechanism. Furthermore, there is little significant difference between the erosion rates and the jet angles of 30 and 90 degrees.