超音速电弧喷涂Al涂层在污水储罐中的腐蚀行为  

Corrosion Behavior of Supersonic Arc Spraying Al Coating in Sewage Storage Tanks

作　　者：周攀虎 周勇[1] 董会[1] 孙良 边颖帅 ZHOU Pan-hu;ZHOU Yong;DONG Hui;SUN Liang;BIAN Ying-shuai(School of Materials Science and Engineering,Xi’an Shiyou University,Xi’an 710065,China)

机构地区：[1]西安石油大学材料科学与工程学院,西安710065

出　　处：《表面技术》2020年第8期73-80,共8页Surface Technology

基　　金：陕西省自然科学基金(2020JM-540);西安石油大学“材料科学与工程”省级优势学科资助项目(YS37020203);西安石油大学研究生创新与实践能力培养计划资助项目(YCS19212056)。

摘　　要：目的研究Al涂层在污水储罐不同位置的腐蚀行为,为热喷涂Al涂层服役提供理论基础。方法采用超音速电弧喷涂在Q235B钢表面喷涂Al涂层,采用扫描电子显微镜(SEM)分析Al涂层腐蚀前后的组织形貌,采用能谱仪(EDS)对涂层元素组成进行表征。通过涂层减薄速率、腐蚀形貌特征等,表征涂层在储罐不同位置(水/气界面、水层、水/泥界面和泥层)的腐蚀行为。结果喷涂态Al涂层为典型的层状结构,未发生明显氧化,孔隙率为5.4%,厚度为60μm。涂层浸泡60 d后,水/气界面和水层环境中涂层表面仍保持喷涂态的典型特征,即液滴铺展形成的光滑区域和液滴飞溅形成的粗糙区域。由于初始产物的堵塞隔离作用在涂层表面生成氧化膜,涂层发生的腐蚀形式为均匀腐蚀。水/泥界面和泥层环境中,由于氧浓差腐蚀等因素,使得涂层氧化膜的腐蚀速率大于其钝化速率,涂层腐蚀严重,出现局部腐蚀坑、裂纹和脱落现象,主要发生一层或几层扁平粒子整体剥落造成的局部腐蚀。另外,泥层腐蚀环境中,整个涂层内部的扁平粒子界面已完全腐蚀,涂层为松散状态。结论与海洋中相比,铝涂层在污水储罐中的腐蚀机理有所差别。与普通储罐相比,阳极铝涂层保护储罐的腐蚀形式不同,但是超音速电弧喷涂Al涂层,在此实验环境中保护前后,污水储罐最易失效的位置相同,都为泥层环境。The work aims to provide the theoretical basis for the service of Al coating by studying the corrosion behavior of thermal-sprayed Al coating in different positions of the sewage storage tank.Al coating was deposited on the surface of Q235B steel via supersonic arc spraying.Scanning electron microscopy(SEM)was employed to analyze the microstructure and morphology of the Al coating before and after corrosion and the energy dispersive spectrometer(EDS)was used to characterize the elemental compositions in the coating.The corrosion behavior of coating at different positions of the tank(water/air interface,water phase,water/mud interface and mud phase)was characterized via the thickness reduction rate and corrosion microstructure.The Al coating presented a typical lamellar structure with the porosity of 5.4%and the thickness of 60μm.Additionally,the coating had no evidently oxidation.After immersion for 60 days,the surface of the coating in the water/air interface and the water phase environment still maintained typical characteristics of the as-sprayed coating,i.e.the smooth area formed by droplet spreading and the rough area formed by droplet splashing.The corrosion form of the coating was uniform corrosion because the clogging isolation of the initial products formed oxide film on the coating surface.Due to the factors,such as oxygen concentration corrosion,the corrosion rate of coating oxide film in the water/mud interface and the mud phase environment was higher than passivation rate.The coating had serious localized corrosion,and showed some cracks and spallation during immersion in the water/mud interface and the mud phase.The local corrosion caused by integral peeling of one or several layers of flat particles mainly occurred.In addition,the splat particle interfaces inside the entire coating in the mud phase corrosion environment were all completely corroded,which induced the generation of loose coating.The corrosion mechanism of Al coating in the sewage storage tank is different from that in the ocean.The

关 键 词：污水储罐 超音速电弧喷涂 铝涂层 腐蚀区域 耐蚀性 腐蚀机理 

分 类 号：TG174.44[金属学及工艺—金属表面处理]