Effect of Powder Particle Size on Microstructure and Mechanical Properties of Cold-Sprayed Pure Nickel Coatings

In this study, the effect of particle size on the microstructure and mechanical properties of cold-sprayed nickel coatings was investigated using three particle size ranges of pure nickel powders. The experimental results show that the mechanical properties of the coating fabricated by the fine powder with a D₅₀ of 25 μm are lower (microhardness and tensile strength of 257.5 HV_0.1 and 126 MPa, respectively) compared to those from the coarser particle sizes (D₅₀ = 45 μm and 67 μm) because of the higher yield strength of powder, which makes it difficult to generate sufficient plastic deformation during the spraying process. The powder with the largest particle size, D₅₀ of 67 μm, has a low impact velocity, which does not allow for a high-quality coating due to less plastic deformation, and the porosity is higher up to 0.7%. When the mean particle size of the powder is 45 μm, the coating shows the highest degree of densification, the porosity is 0.4%, and the mechanical properties of the coating are better with the microhardness and tensile strength of 289.2 HV_0.1 and 208 MPa, respectively.