Preparation and properties of Ni-SiO2 superhydrophobic coating by brush plating on inner wall of pipeline

Abstract

Coal is easy to stay on the inner wall of the pipeline during transportation. In order to solve this problem, it is usually necessary to improve the hydrophobicity of the inner wall of the pipeline. In this study, 45 # steel, which is wear-resistant and has good machinability, is used as the matrix for coal pipeline. Ni-SiO2 composite coatings were prepared on the inner surface of 45 # steel pipelines using a novel brush plating tool, and the hydrophobicity of the coatings were evaluated. Firstly, a series of four-factor and three-level orthogonal tests were conducted to investigate the impact of brush plating working voltage (12V, 14V, 16V), nanoparticle concentration (1g/L, 2g/L, 3g/L), brush plating duration (2min, 3.5min, 5min), and bath temperature (25 ℃, 35 ℃, 45 ℃) on the hydrophobicity of the composite coating. Subsequently, optimum process parameters were determined. Then 1H, 1H, 2H, 2H- perfluorodecyltrimethoxysilane was used to modify the coating surface in order to further improve its hydrophobicity. Scanning electron microscope (SEM), energy spectrum analyzer (EDS), optical contact angle measuring instrument, white light interferometer, Vickers hardness tester, scratch tester, friction and wear meter and electrochemical workstation were used to evaluate the coating's related properties. The experimental results show that the Ni-SiO2 nano-composite coating has a higher angle (135°) when the operational voltage of brush plating is 14V, the amount of nanoparticles is 3g/L, the brush plating time is 2min, and the bath temperature is 35 ℃. The concentration of nanoparticles is the biggest factor affecting the hydrophobicity through orthogonal test analysis, so the control variable method is used to further study the influence of the concentration of nanoparticles on the comprehensive performance of the coating. It was found that with the increase of nanoparticle concentration, surface quality and comprehensive performance of the coating showed a trend of increasing first and then decreasing, and the surface of the coating was rougher when the nanoparticles were added at 4g/L, and the maximum porosity was 31.34%. At this time, the contact angle of the super hydrophobic coating has reached 150.1°, which has reached the super hydrophobicity, and the coating has good hardness, wear resistance and corrosion resistance.