On The Preparation And Anti-corrosion Performance Of Electroless Composite Coating Containing MoS₂ Nanoparticles

Electroless plating technology is an effective means in surface treatment. It can be used for compositing nanoparticles in coatings via electroless plating technology in order to take use of some advantages of nanoparticles. However, the dispersion of nanoparticles in plating bath is one of key steps to obtained desired plating coatings.In this thesis, it studied the suitable surfactant to disperse the nano-MoS2 particles in the nickel-electroless bath. At first, anionic surfactant, cationic surfactant, non-ionic surfactant and their mixture were used to measure their sedimentary properties. According to the respective microstructures of the composite coatings with nanoparticles, the optimum allocation were selected via using a compositing surfactant of cationic (cetyltrimethyl ammonium bromide, C₁₉H₄₂BrN) + non-ionic (Tween-80). At the same time, both mechanical stirring and ultrasonic dispersion technique were also applied together to disperse M0S2 nanoparticles in the electroless plating process.After using the single factor method to analyze main parameters such as the content of nano-MoS2 powder in the bath, pH range and temperature of the bath, the optimal process parameters of preparing electroless plating coating with nanoparticles were gained via the orthogonal test. The optimized process parameters were as follows: content of nano-MoS2 particles 2g/L; pH 4.6 and temperature 88℃.The thickness, hardness, porosity, cohesive strength and wear resistance of the composite coatings were measured respectively. The results indicated that the composite coatings with P content of 10.23 wt% and M0S2 content of 3.18wt% prepared showed better comprehensive properties.The corrosion resistance of the composite coating was investigated by weight loss method and electrochemical measurement. Meanwhile, the corrosional surfaces were studied and analyzed through optical microscope, X-ray spectrometer (XRD) and scanning electron microscopy (SEM). The anti-corrosion mechanism of the composite coatings was also discussed in 3.5% NaCl solution. The investigation on the relationship between heat-treatment and the corrosion resistance of the composite coating showed that the corrosion resistance became worse because of the occurrence of transformation from non-crystalline to crystalline, and then increased the metastable intergradation of the composite coating in the salt spray test.