Copper metallization of carbon fiber-reinforced epoxy polymer composites by surface activation and electrodeposition

• Published in: Surface & coatings technology 2024-07, Vol.487, p.131016, Article 131016
• Main Authors: Basheer, Bashida, Akhil, M.G., Rajan, T.P.D., Agarwal, Pankaj, Vijay Saikrishna, V.
• Format: Article
• Language: English
• Subjects: Adhesion; Electrical conductivity; Electrodeposition; Epoxy‑carbon fiber composite; Sn/Ag activation; Surface activation
• ISSN: 0257-8972
• DOI: 10.1016/j.surfcoat.2024.131016

The application of polymer metallization in lightweight and high-strength materials for the sporting goods, automotive, aerospace and construction sectors has attracted considerable attention. The present study aims to deposit a thin, uniform copper (Cu) layer on an epoxy‑carbon fiber (epoxy-Cf) composite material for lightweight, high-frequency radio reflector applications (Ka-Band and higher frequencies) required in space missions. In this work, a surface-activated electroplating technique in which the surface of the substrate is activated with a Sn/Ag system, followed by conventional electroplating is studied. Surface activation deposits layers of conducting metal ions on the surface of the epoxy-Cf composite, which significantly improves the electrical conductivity of the composite surface. The subsequent electrodeposition takes place from a CuSO4 solution with a pH value of 4 at three different current density values of 0.05 A/dm2, 0.5 A/dm2 and 1 A/dm2. The presence and abundance of metallic Cu over epoxy-Cf composite were confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. The morphology and elemental composition of the coating were characterized by scanning electron microscopy equipped with energy dispersive spectroscopy. With current density and coating thickness, morphology of the deposit changed from cauliflower-like to spherical along with grain refinement. Microhardness test shows a hardness of 330 HV and the pull-off adhesion test gave a bond strength of 1.69 MPa for 27.56 μm thick copper deposit. A major challenge encountered during the deposition of Cu is the oxidation of the metal followed by immediate tarnishing. This issue has been effectively addressed by employing benzotriazole solution as a protective agent. •Electrolytic Cu metallization of surface activated CFRP•Surface activated CFRP shows two-fold increase in surface electrical conductivity.•The thickness, morphology and grain size of Cu can be tuned with current density.•Adhesion strength and microhardness of Cu improved with current density.•Benzotriazole treatment imparts oxidation resistance to the deposited copper.