A Numerical Approach to Study the Oxide Layer Effect on Adhesion in Cold Spray

Due to the high strain rate deformation of particles in cold spray (CS), in situ investigation is challenging. It has been shown that metallurgical bonding is one of the main adhesion mechanisms of particles during coating buildup. Although several numerical studies have been done to study CS particle impact, very few were able to predict the occurrence of bonding based on the process physics. In this study, a novel finite element method is proposed to predict the occurrence of localized metallurgical bonding in the CS process that accounts for the native oxide layer which covers copper particles. The predicted critical velocity of was compared to experimental data to validate the proposed model. In addition, it was shown that the predicted bonding locations at the particle/substrate interface are consistent with experimental observations. The oxide removal process during impact was observed, and its effects on particle deformation/deposition were explained. Moreover, the effects of the oxide thickness and the impact velocity on the particle deposition were investigated and compared with experimental data. This comparison again illustrated the ability of the proposed model in predicting the material behavior during the deposition process. (AU)