Cold gas sprayed filler coatings for brazing of light alloys

Application of cold gas spraying to the deposition of braze filler coatings has been investigated. Different light weight alloy substrates, i.e. aluminium AA1050, AA3005, AA5754, AA7022, magnesium AZ91 and titanium Ti-6Al-4V, were used. Filler coating materials depend on the substrate melting temperature. Therefore, for aluminium alloys Al-12Si zinc based fillers are used for AZ91 pure zinc and for Ti-6Al-4V different Cu-Ni blends are used. Cold gas spraying process parameters are varied with regard to process gas (nitrogen) temperature and pressure, powder feedrate and spray distance. Correlation of the process characteristics to economical aspects is given. The viability of the filler coatings produced is illustrated by different optimised brazing/soldering processes. In the case of aluminium braze joints a full metallographical investigation was carried out by optical and scanning electron microscopy as well as EDX analyses. The results obtained are compared with those of conventional filler material additions.