Hybrid Metallic Coatings on Polymer-based Composites

Carbon fiber-reinforced polymer composites (CFRPs) are poor electrical conductors; hence, they are susceptible to structural damage from lightning strikes. Metallization of the composites through several approaches, including cold spray (CS), has been an active area of research. Previous study showed that Cu can be cold sprayed onto a CFRP if a Cu electroplated interlayer is deposited prior to cold spray. In addition, erosion of the electroplated layer was caused by cold spray deposition of Cu particles. In this present study, Cu powders were cold sprayed onto an electroplated Ni interlayer to address the erosion problem. Deposition efficiency (DE) of the cold-sprayed coatings was measured and characterization of the coatings through scanning electron microscopy and microhardness were performed. The results showed that relative hardness of the particle to the substrate played a significant role in deformability of the particle and the subsequent DE. Therefore, cold spray deposition of soft Cu particles onto a hard Ni interlayer was not possible due to the variation of their hardness values. These results suggest that the hybrid coating can be fabricated with suitable DE only if the substrate and deposited materials have similar hardness values.

 

Keywords: Cold spray; Deposition efficiency; Hybrid coating process; Lightning strike.