含砂海水中环氧树脂/Q235钢体系的冲刷腐蚀行为研究

目的 研究环氧树脂/Q235钢体系在含砂流动海水中的耐冲刷腐蚀性能.方法 采用旋转冲刷腐蚀试验装置进行不同流速、不同含砂量下环氧树脂/Q235钢体系的冲刷腐蚀试验,利用表面观测、电化学测试以及扫描开尔文探针(SKP)技术研究冲刷腐蚀后体系的腐蚀规律.采用计算流体动力学(CFD)方法模拟计算冲刷流场和砂粒分布.结果 高流速下的砂粒不断冲击涂层表面,导致涂层破损,使基体与海水直接接触,造成基体腐蚀,基体腐蚀又导致涂层的进一步破损.当冲刷流速在5～6 m/s之间时,涂层发生破坏,涂层底部腐蚀连接成片,生成片状腐蚀产物,腐蚀产物表面有较长裂缝.当含砂量达到1.5％(质量分数)时,涂层也发生破坏,但是其以孤立的腐蚀坑为主.Q235钢基体发生点蚀后,点蚀周围的腐蚀敏感性增加.随着腐蚀时间的增加,阳极区逐渐变宽,阴极区逐渐向外移动.腐蚀区域逐渐扩大,形成腐蚀通道.最终,腐蚀通道相互连接,从而在涂层下引起更大范围的腐蚀.结论 与含砂量相比,环氧树脂涂层的冲刷腐蚀对流速敏感性更高.

Erosion-corrosion Behavior of Epoxy Resin/Q235 Steel System in Flowing Seawater Containing Sand Particles

The work aims to study the erosion-corrosion (E-C) resistance of epoxy resin/Q235 steel system in flowing seawater containing sand. The erosion corrosion test of epoxy resin/Q235 steel system with different velocity and sand content was carried out by using the rotary E-C test device. The corrosion behavior of the system after E-C was studied by surface observation, electrochemical test and Scanning Kelvin Probe (SKP) technique. The computational fluid dynamics (CFD) method was used to simulate the flow field and sand distribution. The results show that the sand particles at high speed continuously impact the surface of the coating and results in surface damage. After the coating is damaged, the substrate is in direct contact with the seawater, which causes the substrate corrosion, and further damages the coating. The coating damages when the eroding velocity is between 5 m/s and 6 m/s. The bottom of the coating is corroded and connected into pieces, and forms sheet corrosion products. There are long cracks on the surface of corrosion products. Moreover, the surface of the sample is partially damaged as the sand content reaches 1.5wt%. The E-C form is mainly isolated corrosion pits. With the increase of corrosion time, the anode area becomes wider and the cathode area moves outward. The corrosion area expands gradually, forming corrosion channel, and as a result, causes extensive corrosion under the coating. The coating damage is more sensitive to the flowing rate as compared with the sand content.