A comparison of cold spray deposition behavior between gas atomized and dendritic porous electrolytic Ni powders under the same spray conditions

Two Ni powders, a porous dendritic electrolytic nickel (E Ni) powder and a gas atomized nickel (GA Ni) powder, were cold sprayed under the same spraying parameters to evaluate the dependence of deposition behavior on powder microstructure. GA Ni powder was not successfully deposited while a dense coating was obtained with porous irregular E Ni powder with a high deposition efficiency of 73.3%. This was ascribed to both irregular morphology and porous microstructure of E Ni particles. With a particle preheating step, irregular morphology contributes to both higher impact velocity and higher particle temperature. Porous microstructure leads to lower critical velocity. The results indicate that, via introducing irregular morphology and/or pores into the feedstock, metallic coatings of high quality can be easier deposited by cold spray.