Study on Cold Spraying of Al-based Brazing Alloys

The cold spray process is interesting for brazing technology due to its special properties: low oxidation of spray materials and rupture of oxide scales on the substrate and particles surfaces during deposition. In the present study, two brazing alloys AlSi₁₂ and AlSi₁₀Cu₄ were deposited onto 6063 and 3003 aluminium alloys using the cold spray process. The influence of the spray parameters on the particle velocity was investigated by means of DPV 2000. The influence of spray materials and parameters on coating build up and on coating microstructure was investigated. Some of the AlSi₁₂ coated samples were heat-treated at 500 and 600 °C to investigate the effect of the rupture of oxide scales on the diffusion processes. Some of the AlSi₁₂ deposited samples were brazed under argon atmosphere using a flux or without any fluxes. The results show that the process gas temperature influenced the particle velocity and the deposition behaviour of the powders significantly. The AlSi₁₂ powder showed a much better deposition behaviour than the AlSi₁₀Cu₄ powder. Due to the rupture of oxide scales, silicon in the brazing alloy coating could diffuse into the substrate. The brazed samples show a very good bond between the substrate and the brazing alloy.