Investigation of impact behavior of cold-sprayed large annealed copper particles and characterizations of coatings

摘要

In this research, large gas-atomized copper powder was selected as the feedstock. Some powder was annealed in a vacuum circumstance to avoid to the greatest extent the effect of grain boundaries on the high velocity impact behavior of particles during cold spraying. Some powder was oxidized in a resistance furnace to clarify the effect of surface oxide films. Both the annealed and the oxidized Cu powders were deposited by cold spraying with respect to the single impacts and coating deposition under the same gas condition. In addition, the rebounded copper particles were collected for morphology analysis compared to the adhered particles. The results show that the average size of the rebounded particles is apparently increased compared to the starting powder because of the rebound of the larger particles and the intensive plastic deformation of particles. For the deposited particles, obvious plastic deformation causes the higher hardness of the coatings. The last but not the least finding in this study is the rebounded particles also experienced large deformation and possible shear instability at the impact interfaces.