Abstract
In low-pressure cold spray (LPCS) process, compressed air is used as a process gas. The most important process parameters are the gas (air) preheating temperature and the gas pressure. Maximum preheating temperature of air is 650ºC and pressure is 9 bar in the LPCS system used in the present study. Powders used in LPCS process contain hard particles (Al2O3) with metallic powders. LPCS is the method to spray soft metallic coatings with ceramic hard phase for different application areas. For example LPCS opens a way to produce thick coatings for electrical and thermal conductive applications and for corrosion protection. Aim of this study was to investigate microstructural properties such as microstructure and denseness of LPCS coatings. Also mechanical properties (hardness and bond strength) were studied. One interest of this study was to clarify the effect of hard phase on different coating properties. Coating materials were Cu, Ni, and Zn. Substrate material were carbon steel and copper. LPCS coatings seemed to be dense according to SEM studies but corrosion tests were needed to identify existence of porosity. Through-porosity was observed in the structures of the LPCS coatings during the corrosion tests. Bond strengths of LPCS Cu and Zn coatings were found to be reasonable and furthermore, hardnesses were quite high indicating reinforcement effect of hard phase and work hardening.
