Abstract

A previous study showed that Cu can be cold sprayed onto carbon fiber-reinforced polymers (CFRPs) if a Cu interlayer is deposited prior to low-pressure cold spraying. In this present study; one layer of Cu powders was cold sprayed onto a Sn cold sprayed CFRP and a Ni electroplated interlayer. Two layers of Cu powders were also cold sprayed onto a Cu electroplated CFRP to investigate the effect of second particle layer on deposition efficiency/behavior of the impacting particles. Deposition efficiency (DE) of the cold-sprayed coatings was measured and characterization of the coatings with scanning electron microscopy and microhardness testing were performed. The results showed that relative hardness of the particle to the substrate played a significant role in deformability and impact mode of the particle; as well as the subsequent DE. Therefore; cold spray deposition of Cu particles onto a soft Sn interlayer and a hard Ni interlayer was not possible due to interlayer erosion and the presence of a very hard substrate; respectively. DE of Cu-on-Cu coated CFRP decreased as compared to one pass spraying; due to rebounding of the particles from a harder interlayer (first-layer coating) than the electroplated layer underneath. These results suggest that for a low-pressure cold spraying; Cu can be successfully cold sprayed onto an electroplated Cu interlayer due to the similarity in their hardness values while spraying one layer. However; spraying further passes resulted in rebound of the particles and decrease in overall DE.

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