含氟聚氨酯防护涂层体系在模拟海洋环境下的防护性能

Protective Performance of Fluoropolyurethane Coating System in Simulated Marine Environment

目的考核评价Q345低合金钢表面“热喷锌铝基底”和“磷化膜基底”的含氟聚氨酯防护涂层体系在模拟海洋环境下的防护性能。方法分别制备2类含氟聚氨酯防护涂层体系划痕和非划痕试样,采用实验室多因素组合循环试验方式对涂层试样进行模拟加速试验,分析涂层的外观、光泽、色差的变化情况;对比分析划痕部位涂层的耐腐蚀扩展性能,并采用金相法分析热喷锌铝层试验前后的截面变化;分别采用傅里叶变换红外光谱和电化学阻抗谱表征涂层的老化特征和电化学性能。结果2类含氟聚氨酯防护涂层体系试验后的变色等级为1级,失光等级为2级,保护性漆膜综合老化性能等级为0级。磷化膜基底层试样划痕部位的含氟聚氨酯防护涂层出现了鼓泡、锈蚀等现象,单边腐蚀宽度为9.18 mm;热喷锌铝基底层试样划痕部位的含氟聚氨酯防护涂层未出现鼓泡现象,单边腐蚀宽度仅为2.58 mm。含氟聚氨酯防护涂层红外光谱特征峰的形状、位置、强度均未发生明显变化;磷化膜基底层试样涂层体系0.01 Hz阻抗模值(|Z|0.01 Hz)为2.3×10^(9)Ω·m^(2),热喷锌铝基底层试样涂层体系0.01 Hz阻抗模值(|Z|0.01 Hz)为4.6×10^(9)Ω·m^(2)。结论含氟聚氨酯防护涂层具有较好的抗光老化和耐蚀性能。热喷锌铝基底层相较于磷化膜基底层,不仅可以提高涂层体系的持久耐蚀性能,而且能够有效缓解涂层破损后发生的腐蚀扩展现象。

Under the marine atmospheric environment,due to the combined effect of strong solar radiation,high temperature,high humidity and Cl^(−),the resin macromolecules of polyurethane coating are prone to aging and degradation,resulting in discoloration,powdering and decline in protective performance of the coating surface,which seriously affects the safety of equipment service.Based on this background,many new protection systems have been developed to improve the coating performance.It is very important to quickly evaluate the performance of these coatings in marine environment.The work aims to evaluate the protective performance of"hot sprayed zinc aluminum base fluoropolyurethane heavy protective coating system"and"phosphating film base fluoropolyurethane heavy protective coating system"on Q345 low alloy steel surface in simulated marine environment.Q345 steel was into long squares of 100 mm×35 mm×20 mm as the base materials.The phosphating sample plate and hot sprayed zinc aluminum alloy sample plate were prepared.Then,fluoropolyurethane coating system was sprayed on the surface of the test sample,and scratch samples and non-scratch samples were prepared respectively,and simulated accelerated tests were carried out on the coating samples by laboratory multi-factor combined cycle test.The changes of appearance,gloss and color difference of the coating were analyzed.The corrosion resistance of the coating at the scratch position was compared and analyzed,and the cross-section changes of the hot sprayed zinc aluminum coating before and after the test were analyzed by metallographic method.The aging characteristics and electrochemical properties of the coating were characterized by Fourier transform infrared spectroscopy and electrochemical impedance spectroscopy.After the test,the discoloration grade of two types of fluoropolyurethane protective coating systems was grade 1,the light loss grade was grade 2,and the comprehensive aging performance grade of protective paint film was evaluated as grade 0.The fluoropolyurethane heavy protective coating on the scratch part of the sample of the phosphating film base layer bubbled and rusted,and the unilateral corrosion width was 9.18 mm.The fluoropolyurethane heavy protective coating on the scratch part of the hot sprayed zinc aluminum base layer sample did not bubble,and the unilateral corrosion width was only 2.58 mm.The shape,position and intensity of characteristic infrared peaks of fluoropolyurethane protective coating did not change significantly.The impedance modulus|Z|at 0.01 Hz of the coating system of the phosphating film base layer sample was 2.3×10^(9)Ω·m^(2) and thermal sprayed zinc aluminum base layer sample was 4.6×109Ω·cm2.Fluoropolyurethane protective coating has good light aging resistance and corrosion resistance.Compared with the phosphating film base layer,the hot sprayed zinc aluminum base layer can not only improve the durable corrosion resistance of the coating system,but also effectively alleviate the corrosion expansion after the coating is damaged.The fluoropolyurethane heavy protective coating system based on hot sprayed zinc aluminum layer can be used as a metal surface protection technology in marine environment.