Structure, electrochemical and wear-corrosion properties of electroless nickel–phosphorus deposition on CFRP composites

Abstract

This work evaluates the microstructure, and mechanical, elcetrochemical and wear-corrosion properties of electroless nickel–phosphorus (ENP) coatings on carbon-fiber-reinforced plastic (CFRP) composites commonly used in aeronautical and astronautical applications due to their superior properties such as high specific strength and modulus. Experimental results demonstrate that a uniform ENP coating was successfully deposited on a CFRP substrate via electroless plating after appropriate sensitization, activation and mechanical polishing pre-treatments of the CFRP substrate exhibited excellent protection from corrosion and wear corrosion for CFRP composites. The microstructure, phosphorus content, thickness and electrochemical and wear-corrosion properties of the ENP coatings were strongly correlated with the pre-polishing condition (the corresponding surface roughness) of the CFRP substrate. High P content (P > 7 wt.%), low micro-porosity, smooth morphology, high thickness and hardness of ENP coatings on the CFRP substrate were obtained when substrate surface roughness was ≥0.3 μm (grinding with 800-grade emery paper). The resulting electrochemical behavior exhibited a strong passivity that is favorable to enhanced wear-corrosion resistance properties.