Influence of Secondary Parameters in Cold Gas Spraying of Al6061

Systematic studies on optimizing deposit performance in cold spraying mainly concern the variation of primary process parameters as gas pressure and gas temperature. However, energy densities of the spray-jet exposed to the deposit surface might have similar influence as substrate heating. In order to supply more details, this study systematically investigates the influence of secondary parameters by robot kinematics on deposit performance. As model material, an Al6061 powder in sizes of 20-45μm was cold sprayed on Al6061-T6 substrates. Fixed primary spray parameter sets were adjusted for sufficiently high impact to critical velocity ratios. Secondary parameters were varied with respect to the standoff distance, the spray velocity of the cold spray gun, the line spacing and the powder feed rate. Deposit analyses concerned deposition efficiency, microstructure, porosity, hardness and electrical conductivity. The results show that lower spray velocities and to some extend shorter stand-off distances lead to better deposit performance. In addition, lower feed rates prove as beneficial for reaching better deposit properties. The findings are discussed in terms of locally reached surface temperature and particle impact energy. The study thus suggests that careful tuning of secondary parameters can be used as additional tool for adjusting the needed deposit performance.