Effect of Carbon Fiber Orientation when Cold Spraying Metallic Powders onto Carbon Fiber Reinforced Polymers

Carbon fiber reinforced polymers (CFRPs) have outstanding strength-to-weight ratios and are widely implemented throughout the aerospace and energy sectors. However, the properties of CFRPs can be affected by differences in the distribution and orientation of the carbon fibers, which can play a role when searching to modify the surface properties of the substrate, notably through metallization. A previous study on the pull-off testing of CFRPs via cold spray showed that better adhesion strengths could be obtained when near-surface features such as carbon fibers or surfacing elements were present, and provided potential to obtain mechanical interlocking. This study explores the effect of the fiber orientation (i.e. unidirectional vs. perpendicular to the substrate) on the deposition and bonding of a pure metallic (Sn) coating to a thermoplastic Polyether-Ether-Ketone (PEEK)-CFRP substrate. Characterization of the coatings was performed and some aspects of tribological testing (namely wear and transverse scratch testing) were carried out to assess the effect of the substrate on the properties of the coatings. Initial results seem to indicate that the perpendicular fibers lead to better coating deposition. A strong emphasis will be placed on the correlation between the interfacial processes and wear behavior of the coatings.