Effect of electroless process parameters for nickel-phosphorous coatings on carbon fibres

Purpose - The purpose of this paper is to investigate the deposition of uniform, adherent and crack-free Ni-P thin films on carbon fibres using the electroless deposition technique. Design/methodology/approach - Before applying the electroless process, the carbon fibre surfaces must be subjected to several treatment processes to remove the organic binder, etching and surface metallization. The surface morphology of the Ni-P coatings was assessed using a scanning electron microscope (SEM). The chemical compositions of Ni-P layers were identified by energy dispersive X-ray analysis (EDS). The bond strength of the coated layer was determined by measuring the electrical resistance at the fibre/coating interface. The magnetic properties of the fibres were estimated using a hysteresis diagram. The tensile performance of single fibres coated by Ni-P has been investigated with respect to coating thickness. Findings - Pre-treatment processes are used to improve the adhesion of Ni-P layers and to obtain homogeneous coatings. The influence of plating parameters (temperature, pH and time) on the coating thickness of the Ni-P layer was investigated. It was found that the coating thickness increased as the pH value, plating time and the temperature of the bath increased. The results revealed that a complete and uniform Ni-P coating on fibre could be obtained at optimum conditions 85 degrees C, pH 6, for 60 min, and the results indicated that the P content in the electroless deposit is approximately 3.4 wt%. The tensile strength values are improved significantly after coating and increased by 3-5 times with increasing of coating thickness from 0.3 to 2 mu m. Originality/value - The results presented in this work are an insight into understanding of the deposition and adherence of Ni-P thin films on carbon fibre using the electroless technique and behaviour of the coated fibre.