Preparation and simulation of cold sprayed copper coatings on metal substrate

Experimental study on preparation of copper coatings on three typical metallic substrate was been carried out on self-made equipment.Under same process conditions,copper coatings on copper and aluminum substrate were successfully produced by cold-gas spraying,however,the coating was not obtained on steel substrate.Microstructure and phases of the coating was examined by means of SEM and XRD,and hardness of the coatings was tested.The results show that the interface between coatings and substrate,and the interface between particles are well bonded.Average microhardness of the coatings is about 150HV0.1.Jet-like metal is observed on the coatings surface,indicating adiabatic shear instability and severe deformation occurs in particles,and the compression rate of particle reachs 69% by computation.No oxidation of the copper powder occurs in the process of spraying.The process of copper particles impacting on the substrate was numerically simulated,and the criterion for effective bonding was discussed.The critical deposition velocities of copper on copper,aluminum and steel substrate are 600m/s,500m/s,and 800m/s,respectively,based on the simulation.This can explain the different deposition behavior of copper particle on three substrate.