Deposition Features of Ti Coating Using Irregular Powders in Cold Spray

The investigation on the deposition features of irregular Ti powders coated on Al and stainless steel (SS) substrates was conducted in this study. Ti coating was experimentally produced at different gas inlet temperatures, and then detailed analysis on the critical velocity, coating microstructure, porosity, and microhardness was performed. As an assistant method, numerical simulation was also adopted to study the deformation features of single-irregular Ti particle during the cold spray process. The results reveal that the critical velocity of Ti particle on Al substrate is higher than that on SS substrate due to the different substrate hardness. The coating porosity is shown to be decreasing as the inlet temperature increases and independent to the substrate material. Similar phenomenon is also noticed for coating microstructure, but the changing trend is reverse in this case. Finally, the most important finding is that an additional torque imposed on the irregular particle is generated during the deposition process, which tends to detach the bonded particle from the substrate surface.