NiCrAl-NiC封严涂层在硫氯酸盐中的热腐蚀行为

Hot corrosion behavior of NiCrAl-NiC sealing coating in thiochlorate

为探究NiCrAl-NiC封严涂层在高温熔盐环境下的腐蚀行为,使用大气等离子喷涂技术制备NiCrAl-NiC封严涂层。通过测量NiCrAl-NiC封严涂层的失重情况研究涂层的动力学变化,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、激光共聚焦显微镜等方法,探讨NiCrAl-NiC封严涂层在650℃下混合硫氯酸盐(75%Na_(2)SO_(4)+25%NaCl)中的热腐蚀行为。结果表明:在进行10 h的热腐蚀实验后,NiCrAl-NiC封严涂层呈现出快速增重状态,增重速率为32.041 mg^(2)·cm^(-4)·h^(-1)。在进行20 h的热腐蚀实验后,涂层由于表面氧化膜的脱落而发生减重现象。在热腐蚀进行了30 h后,涂层表面膜的生长覆盖了整个涂层,涂层表面形貌均匀,表面孔隙减少,可以对基体起到很好的保护作用。在完整的氧化膜的保护作用下,进行了40 h热腐蚀实验的NiCrAl-NiC封严涂层的质量变化速率为0.064 mg^(2)·cm^(-4)·h^(-1);通过XRD测试探究涂层热腐蚀后氧化膜的组成,发现热腐蚀后涂层表面的氧化膜以NiO和NiCr_(2)O_(4)为主。在热腐蚀过程中,尖晶石结构的NiCr_(2)O_(4)对涂层的热腐蚀起到了阻碍作用,是涂层腐蚀进程缓慢的主要原因。

To investigate the corrosion behavior of NiCrAl-NiC sealing coating in high-temperature molten salt environments,NiCrAl-NiC sealing coating was prepared using atmospheric plasma spraying technology.By measuring the weight loss of NiCrAl-NiC sealing coating,the dynamic changes of the coating were studied.The thermal corrosion behavior of NiCrAl-NiC sealing coating in a mixture of thiochlorate(75%Na_(2)SO_(4)+25%NaCl)at 650℃was discussed using scanning electron microscopy(SEM),X-ray diffraction(XRD),laser confocal microscopy,and other methods.The results show that after 10 h of hot corrosion experiments,the NiCrAl-NiC sealing coating exhibites a rapid weight gain state,with a weight gain rate of 32.041 mg^(2)·cm^(-4)·h^(-1).After conducting a 20 h hot corrosion experiment,the coating experienced weight loss due to the detachment of the surface oxide film.After 30 h of hot corrosion,the growth of the facial mask on the coating surface covers the entire coating.The surface morphology of the coating is uniform,and the surface pores are reduced,which can play a good role in protecting the substrate.Under the protection of a complete oxide film,the mass change rate of the NiCrAl-NiC sealing coating after a 40 h hot corrosion experiment is 0.064 mg^(2)·cm^(-4)·h^(-1).Through XRD testing,it is found that the composition of the oxide film on the surface of the coating after hot corrosion is mainly NiO and NiCr_(2)O_(4).During the hot corrosion process,the spinel structure of NiCr_(2)O_(4)hinders the hot corrosion of the coating,which is the main reason for the slow corrosion process of the coating.