Sol-gel Method To Prepare Ni-P-SiO₂ Nanocomposite Coating And Its Performance

With the expansion of industrial scale and the development of material science,the properties of nanoparticles have been further studied.The electroless composite plating method can effectively add nanomaterials to the coating.As a result,the hardness,corrosion resistance and bonding strength of the coating have been enhanced to a certain extent,but the effect is not significant.This is due to the dispersion of nanoparticles in the coating.The dispersion of nano particles is usually promoted by physical mechanical dispersing agent or chemical dispersant.The preparation of Ni-P-SiO2 nanocomposite coating by sol-gel method is of great practical significance to the dispersion of nanoparticles and the improvement of coating properties.This paper mainly improves the performance of the composite coating by improving the electroless composite plating process.In this paper,sol-gel method was used to prepare nano SiO2 sol.Through the use of different processes,the sol with good dispersion and moderate particle size was prepared and applied to the chemical composite plating bath to improve the dispersion and binding degree of nano SiO2 particles in the coating.Meanwhile,the degree of dispersion and bonding degree of the coating were recovered by SEM,micro hardness tester,corrosion potentiometer and contact angle measuring instrument.The surface morphology,microstructure,hardness,corrosion resistance and nydrophobicity of the composite coatings were studied.The properties of Ni-P coating were analyzed and compared with those of Ni-P coating.Through experiments,the following conclusions are drawn:1.The ratio of sol reacted material to four ethyl orthosilicate(TEOS)was 3%,the amount of ammonia water was 2mL,and the reaction temperature was set at 30 C.After that,the nano SiO2 sol prepared by sol-gel method showed better stability,characterized by transparency and accompanied by blue light.The average particle size of nano-SiO2 sol prepared under this condition is 45.88 nm,and its dispersion index(PDI)is 0.096.The real problem of nano-SiO2 sol is single peak distribution.The distribution of nano-SiO2 particle size is narrow and uniform as a whole.2.The nano-sol with the best dispersibility was added into the common Ni-P plating solution through a certain proportion to prepare Ni-P-SiO2 composite electroless coating.By comparing and analyzing the micro-structure,element composition and a series of physical and chemical properties of the coating surface,it can be concluded that when the amount of SiO2 sol is 10 ml/L,the dispersion is more uniform and the combination of nanoparticles and the coating is better.3.The composite plating solution was prepared by sol-gel method,and the nanoparticles were combined with the coating evenly distributed inside and outside the surface.Compared with the common Ni-P coating,the hardness of Ni-P-SiO2 nanocomposite coating has been further improved.At the same time,when compared with the common Ni-P coating,the Ni-P-SiO2 coating has higher adhesion,better bonding strength and better wear resistance.Ni-P-SiO2 nanocomposite coatings and common Ni-P coatings were placed in 3.5%NaCl solution at the same time.By testing their polarization curves,it can be concluded that the corrosion resistance of Ni-P-SiO2 nanocomposite coatings is improved compared with that of common Ni-P coatings.The hydrophobicity of composite coatings is also improved compared with that of common coatings.