Development of an epoxy-metallic powder sublayer for the cold spray metallization of carbon-fiber reinforced thermoset composites

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This paper investigates the development of a composite sublayer for the cold spray metallization of carbon-fiber reinforced thermoset composites. The hybrid sublayer/carbon-fiber reinforced structure is prepared using a vacuum assisted infusion process. The sublayer consists of a mixture of epoxy with micron-sized metallic powder particles and is directly embedded onto the carbon-fiber reinforced structure during the infusion process. During the cold spray metallization, the erosion of this biphasic sublayer has the capability to produce a metal-to-metal bonding between the cold sprayed powder particles and the sublayer powder particles. The mechanical response of the sublayer due to the high-speed collision of the cold spray powder is investigated using a computational analysis. A decohesion at the epoxy/metallic particle interface within the sublayer, along with the fragmentation of the epoxy matrix upon impact, eases an erosion that prevents the coating formation onto the sublayer. The erosion/coating formation strongly depends on the mechanical property of the spray powder compared to the powder of the sublayer. In the case of a sublayer made of soft metal particles, the plastic deformation during the high-speed collision is better absorbed by such a biphasic sublayer. This circumstance is conducive to an adhesion of the sprayed particles onto the sublayer despite an occurrence of an erosion. Thus, the cold spray deposition of Cu powder onto a biphasic epoxy/Al sublayer results in deposit formation, with Cu particles bonding to Al particles and anchoring to the epoxy matrix.