Surface modification of carbon-fiber-reinforced plastic by using photo-activated chlorine dioxide radicals as pretreatment of electroless plating

Abstract

Carbon fiber reinforced plastic (CFRP) plays an important role in industrial fields of automobiles, aerospace transportations and astronautics on account of its high stiffness and light weight. To further expand its utilizations, coating with metals can provide with metallic appearance while improving water-resistance, durability and electric conductivity. In general, the composites of CFRP are hydrophobic and have low affinities to metals. Therefore, it requires the surface pretreatments to increase the wettability and surface energy for stronger adhesive properties with metals via enhancing both mechanical and chemical bonding. In this study, photo-oxidized chlorine dioxide radicals were used to introduce oxygen–containing functional groups on CFRP surface. The hydrophilicity and adhesion strength to metals were successfully improved by the introduction of oxygen functional groups via eco-friendly photo-oxidation by photo-activated ClO2• radicals. The improvement of hydrophilicity was determined by water contact angle measurement, and the incorporation of oxygen was confirmed by infrared (IR) and X-ray photoelectron spectroscopy (XPS) analysis. Scanning electron microscopy (SEM) observations revealed that the surface smoothness and structure of CFRP were maintained after pretreatment. Electroless plating of nickel and copper was then performed on both untreated and oxidized CFRP, demonstrating the enhanced adhesion properties of CFRP to both metals.