带冷喷Al/Al_2O_3涂层的20号碳钢管道在保温层下的腐蚀行为

Corrosion Behavior of 20~# Carbon Steel with Cold Sprayed Al-Al_2O_3 Coatings under Insulation

采用浸泡试验模拟涂层管道在保温层下的腐蚀,并通过腐蚀失重法、宏观腐蚀形貌和显微结构观察以及微区成分分析,研究了80℃时,在0.01%(质量分数,下同)NaCl、0.1%NaCl以及1%NaCl溶液中,三种涂层(喷涂粉末分别为100%Al、70%Al+30%Al_2O_3和50%Al+50%Al_2O_3)对20号碳钢管道的防护作用。结果表明:当碳钢管道表面冷喷Al/Al_2O_3涂层后,管道具有较好的抗保温层下腐蚀性能。且当喷涂粉末为纯铝粉时,涂层的耐蚀性最好,加入陶瓷相Al_2O_3后,涂层的沉积厚度与强度均提高,但腐蚀保护效率存在一定程度的下降。综合考虑涂层的耐蚀性和强度,喷涂粉末为70%Al+30%Al_2O_3时所得到涂层最适于工程上使用。

Immersion tests were conducted to simulate the corrosion under insulation （CUI） in 0. 01%, 0. 1% and 10% NaCl solution at 80 ℃. Corrosion protection performance of three different coatings （initial spray powder were 100% Al, 70% Al ＋ 30% Al2O3 and 50% Al＋50% Al2O3 respectively） on 20# carbon steel pipe was analyzed by weight loss, macro-appearance, microstructure and chemical component analysis. The results showed that cold sprayed Al/Al2O3 coating could protect the pipe substance from corrosion under insulation effectively. When Al2O3 was added into spray powder, the deposition efficiency and hardness increased, but the corrosion resistance decreased. Overall, considering both corrosion resistance and strength, the coating sprayed with 70% Al ＋ 30% Al2O3 was most suitable for using in engineering.