Effect of spray conditions on the microstructure and properties of micro-plasma sprayed Cu coating

Cu coating is deposited by microplasma spraying system under a low power of 2.8 to 4.2 kW. The effects of the main processing parameters, including plasma arc power, operating gas flow and spray distance, on the particle velocity during spraying, the microstructure and the hardness of the coating are investigated. The experimental results show that the particle velocity is nearly independent of plasma arc power and spray distance, but is significantly influenced by operating gas flow. Moreover, the microhardness of the coating was influenced significantly by plasma arc power and spray distance, and is influenced weakly by operating gas flow. The analysis suggests that the microhardness of the coating is strongly affected by particle temperature. The comparison shows that the microhardness of Cu coating deposited by microplasma spray is comparable to that of the coating deposited by the conventional plasma spray system at a power level of 30 kW.