前处理清洁度对涂装维修后涂层附着力的影响

Effect of pretreatment cleanliness on adhesion of the coating repainted after repairing

设计了不同前处理清洁度等级的钢板,并模拟桥梁工程涂装维修工况,用环氧底漆和低表面处理环氧底漆分别制备了标准试样、模拟锈蚀试样、模拟维修试样及模拟维修时返锈试样,采用划格法及拉开法测试了盐雾试验前与盐雾试验144 h和240 h后涂层的附着力,分析了不同试样的附着力变化情况。结果表明,维修涂装前处理清洁度对涂层的附着力有明显影响。St3级试样的涂层附着力显著优于St2级试样,划格法附着力评级提升1个等级,破坏强度普遍提高30%。在盐雾试验过程中,St3级试样涂层的破坏强度比St2级试样涂层高70%以上,St2级试样涂层的失效速度显著大于St3级试样涂层。

Some steel plates pretreated with different cleanliness grades were designed,and the painting and repair conditions for bridge engineering were simulated.Standard samples as well as artificially rusted samples,repaired samples,and re-rusted samples were prepared with conventional epoxy primer and low-surface-treatment epoxy primer,respectively.The adhesion of coatings was measured by cross-cut method and pull-off method before and after a 144-hour or 240-hour salt spray test,and the adhesion variation of different samples was analyzed.The results showed that the cleanliness of pretreatment has a great effect on the adhesion of coating.The coating on a St3-grade sample has much higher adhesion than that on a St2-grade sample,which was shown by the fact that the former’s cross-cut adhesion was one grade higher than the latter’s,and the former’s breaking strength was generally 30%higher than the latter’s.During the salt spray test,the breaking strength of the coating on a St3-grade sample was at least 70%higher than that on a St2-grade sample,indicating that the failure rate of the coating on a St2-grade sample was much higher than that on a St3-grade sample.