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The use of advanced thermal spray technology for surface modification of aluminum alloy parts for automobiles can greatly improve the surface properties and service life of the parts while saving resources and reducing environmental pollution. In this paper, a Ni60A coating was prepared on the surface of aluminum alloy 109 (ZL109) by supersonic plasma spraying (HEPJet). The spraying process parameters were optimized based on the response surface methodology (RSM). The effects of the main factors such as spraying power, spraying distance, and Ar flow rate on the porosity and microhardness of the coating were analyzed by the Box–Behnken method (BBD). The response surface of the porosity and microhardness of the coating was constructed by establishing the appropriate mathematical model. The response surface of porosity and microhardness of the coating was constructed by establishing a relevant mathematical model. The results show that the established mathematical model is reliable, and the spray power has the greatest influence on the porosity and microhardness of the coating. The optimal porosity and microhardness of the coating predicted by the model are 0.85% and 971.1HV0.1, respectively, which is close to the experimental results. The porosity and microhardness of the coating measured by the experiment are 0.87% and 959.8HV0.1, respectively. The coatings prepared with optimal parameters have good compactness, small porosity, and high hardness. [ABSTRACT FROM AUTHOR]

Diamond-Cu composites have been considered to be the next generation of electronic packing materials. One of the key stumbles for such an application is the joining problem between diamond-Cu composites and other materials due to the poor wettability of the diamond particles in the composites. In order to overcome this hurdle, pure Cu powder was thermally sprayed onto diamond-Cu substrate by low-temperature high-velocity oxygen fuel spraying process. Microstructure and some fundamental properties of the coating obtained were systematically investigated, and morphologies of the single splat deposited on the diamond-Cu substrate were also observed. The splats obtained have good adhesion with the substrate as fine particles flattened sufficiently, while the coarse particles were significantly deformed. The coating was quite dense with porosity lower than 1%, oxygen content under 0.5% and thermal conductivity about 266 Wm K and still remained on the diamond-Cu substrate after 50 thermal shock cycles between 300 °C and water bath at room temperature. Meanwhile, the solderability of the coating was significantly improved. Therefore, Cu coating deposited on diamond-Cu substrate by low-temperature high-velocity oxygen fuel spraying process can be beneficial in electronic industry assisting with soldering and improved wettability for joining of other materials. [ABSTRACT FROM AUTHOR]