Hydrophobic modification of stainless steel flowing surface with fluorine- free agent for pumped-storage units and its anti-scaling performance
XIONG Tao1, YANG Xiong1, LIU Ze1, ZHANG Yuquan2*, ZHENG Yuan2, XU Qianxin1, PENG Xuyi1
1. Jiangxi Hongping Pumped Storage Co. Ltd., Jing′an, Jiangxi 330600, China; 2. College of Energy and Electrical Engineering, Hohai University, Nanjing, Jiangsu 210098, China
Abstract：In the operation of pumped-storage units, it is urgent to deal with the problems of scaling and corrosion on the surface of the flowing. Here, a hydrophobic surface was constructed on 304 stainless steel substrate via a chemical grafting method by using a fluorine-free silane coupling agent as the hydrophobic modifier and an environment-friendly ethanol as the solvent. The effects of pretreatment on the surface properties of 304 stainless steel substrate, such as microstructure, roughness and contact angle of water droplets were investigated. The influence of the substrate roughness of 304 stainless steel on the contact angle of water droplets after hydrophobic modification was further analyzed. After a serial treatment of the ″pickling—grinding—modification″ on the 304 stainless steel substrate, the contact angle of surface was significantly increased from the initial 81° to 136°. While, the surface free energy was significantly decreased from the initial 35.8 mN/m to 11.8 mN/m. In the continuous simulation scale experiment, the average weight gain rate of the 304 stainless steel substrate after hydrophobic modification was only 0.21 g/(m2·h), which was about 69% slower than that before the modification(0.68 g·m-2·h-1). The results show that the hydrophobic surface of 304 stainless steel can be effectively constructed on the 304 stainless steel substrate by chemical grafting even using a fluorine-free modifier. The anti-scaling performance of the 304 stainless steel surface can be significantly improved after the hydrophobic modification.
