Effect of type of reinforcing particles on the deposition efficiency and wear resistance of low-pressure cold-sprayed metal matrix composite coatings

Abstract

Low-pressure cold spraying was used to deposit boron carbide (B4C), titanium carbide (TiC), and tungsten carbide (WC) based metal matrix composite (MMC) coatings. Nickel (Ni) was used as the matrix and each carbide powder was mechanically blended with Ni powder prior to spraying. The average velocity of the carbide particles and their momentum during the cold spray deposition were estimated using a mathematical model. The effect of the carbide particle momentum on the Vickers micro-hardness and wear resistance was evaluated. The model showed that the average momentum of WC particles was more than two times greater than that of B4C particles and almost six times greater than that of TiC particles. The higher momentum of the WC particles led to a higher level of work hardening of the matrix, which resulted in improvement of the hardness and wear resistance of the MMC coatings. This led to similar hardness values for the deposited MMC coatings (400kg/mm2) despite the difference in hardness of the selected reinforcing carbides. Furthermore, it was found that the high momentum and high fracture toughness of the WC particles increased the roughness of the coating surface and compacted the coating, which led to higher deposition efficiency for this carbide-metal powder blend on previously deposited coating layers. The lowest wear resistance was achieved by the WC-Ni MMC coatings due to the higher fracture toughness of WC particles and also work hardening of the Ni matrix. The results obtained emphasize the importance of the carbide fracture toughness and particle momentum on the deposition efficiency, hardness, and wear resistance of cold-sprayed MMC coatings.