The Effect of Ni Coating for Diamond on the Metal/diamond Composite Coatings by Cold Spray Deposition

Metal/diamond composite coatings on Al substrate without grit blasting were deposited by cold spray process with in-situ powder preheating.  The effect of Ni coating for diamond to reduce the fracturing of the diamond during cold spray process was studied.  Microstructural characterization of the as-sprayed coatings with different diamond size and Ni coating thickness was carried out by OM and SEM.  Assessment of basic properties such as the hardness of the coatings and the deposition efficiency of the diamond was also carried out.  Particular attention on the composite coatings was on the diamond fracture phenomenon during the cold spray deposition and the interface bonding between the diamond and the metal matrix.