摘要
[目的]研究磷酸盐封孔NiCrAlY涂层样品在熔融盐中的高温腐蚀行为及机理。[方法]采用超音速火焰喷涂技术在T91钢表面制备NiCrAlY涂层,用磷酸盐封孔剂对其进行封孔,研究了未封孔涂层及封孔涂层样品在涂覆混合盐膜(Na2SO4与NaCl的质量比3∶1)后在750℃下的加速腐蚀行为。通过X射线衍射仪(XRD)、扫描电镜(SEM)和能谱仪(EDS)分析封孔前后涂层及腐蚀产物的物相组成、微观形貌及元素分布。[结果]腐蚀过程中,未封孔的NiCrAlY涂层出现明显增重,形成了外部为疏松的富Ni层,内部为致密的富Cr层的腐蚀产物结构,并在基体侧发生了氧化和腐蚀。封孔涂层在腐蚀过程中表现为失重,磷酸盐封孔剂涂层在高温下发生相转变,封孔剂涂层外层出现较多空隙,表面出现微裂纹并发生轻微脱落,但是封孔剂涂层内层良好,有效抑制了腐蚀介质向Ni Cr Al Y涂层/基材扩散,未对基材金属造成腐蚀。[结论]磷酸盐封孔处理可有效提升NiCrAlY涂层的耐高温腐蚀性能。
[Objective]The high-temperature corrosion behavior and mechanism of phosphated-sealed NiCrAlY coating in molten salts was studied.[Method]NiCrAlY coatings were deposited on T91 steel via high-velocity oxygen fuel(HVOF)spraying,and then sealed with phosphate.Accelerated corrosion tests were performed on both unsealed and sealed coatings under a mixed salt film(Na2SO4/NaCl mass ration=3:1)at 750°C.The phase composition,microscopic morphology,and element distribution of coatings and corrosion products were analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy-dispersive spectroscopy(EDS).[Result]The unsealed coating showed significant weight gain during the corrosion process,forming a bilayer corrosion structure:a loose Ni-rich outer layer and a tight Cr-rich inner layer,with severe oxidation and corrosion at the substrate side of the coating/substrate interface.The sealed coating exhibited weight loss due to phase transformation of the phosphate sealant at high temperatures.Although voids and microcracks formed in the outer sealing layer resulted in a slight exfoliation,the intact inner layer effectively blocked the diffusion of corrosive media into the coating/substrate interface,preventing the corrosion of substrate.[Conclusion]The high-temperature corrosion resistance of NiCrAlY coating can be improved greatly by phosphate sealing.
作者
董猛
谢逍原
卢宇航
郑志强
熊义
柳志浩
刘光明
DONG Meng;XIE Xiaoyuan;LU Yuhang;ZHENG Zhiqiang;XIONG Yi;LIU Zhihao;LIU Guangming(Key Laboratory of High-temperature and High-pressure Materials and Welding,Mechanical Industry,Dongfang Boiler Group Co.,Ltd.,Zigong 643001,China;School of Materials Science and Engineering,Nanchang Hangkong University,Nanchang 330063,China)
出处
《电镀与涂饰》
北大核心
2025年第5期107-114,共8页
Electroplating & Finishing
关键词
镍-铬-铝-钇涂层
磷酸盐
封孔
熔盐
高温腐蚀
nickel-chromium-aluminum-yttrium coating
phosphate
sealing
molten salt
high-temperature corrosion
