In the present study, application of cold gas spraying technology (CGS) for deposition of braze filler coatings is investigated. Pure copper coating were deposited on magnesium alloy AZ31B substrate by CGS. Then coated magnesium samples were joined to AISi 1008 steel in vacuum furnace by contact reaction brazing (CRB) process. The microstructure of coated and brazed samples was investigated. The experimental results proved the feasibility of using cold spraying coatings as filler interlayer for precision brazing. Cold spraying performed well due to the low thermal impact on the copper powder and the magnesium substrates with low oxygen content. The bonding temperature influenced the dissolution of Cu coatings, as well as the eutectic reaction between Cu coating and magnesium substrate. The initial thickness of Cu coatings was 50pm while the brazed seam has a thickness of 300pm after eutectic reaction. Within a certain range, the shear strength of brazed joints showed a trend of increasing firstly and then decreasing as the heating temperature increased. Maximum shear strength 37MPa was gained at brazing temperature of 530°C and holding time of 60 min for brazed joint. Intermetallic phases and interfacial defects such as microcracks, unmelted coatings, overheated compounds were responsible for the low strength of the joints.
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