目的 为了提高热喷涂涂层在苛刻环境下的耐蚀性，采用封孔剂对热喷涂涂层进行封孔，研究封孔对涂层抗热腐蚀性能的影响。方法 采用超音速火焰喷涂在20#钢表面制备Inconel 625涂层。采用正硅酸乙酯作为封孔剂基料，Cr2O3、Al2O3、ZrO2、CeO2等氧化物为填料，制备了封孔剂，采用封孔剂对制备的涂层进行封孔。研究了封孔剂对涂层耐蚀性能的影响，将封孔和未封孔的涂层涂覆75%Na2SO4+25%NaCl混合盐膜后，在650 ℃下进行腐蚀，间隔一定时间取出样品称量，获得腐蚀动力学曲线。采用XRD、SEM、EDS对高温腐蚀产物成分、结构、形貌进行分析。结果 未封孔的Inconel 625涂层腐蚀160 h后增重约4.4 mg/cm2。表面腐蚀产物有双层结构，外层富Ni较疏松、多孔，内层富Cr较为致密。同时涂层/腐蚀层界面一侧有S元素富集。封孔层在高温熔盐中轻微熔解，封孔样品腐蚀160 h后，失重仅约0.45 mg/cm2。在腐蚀过程中Ni通过封孔层向外扩散并被氧化，生成的氧化物可填补封孔层缺陷。涂层/封孔层界面形成富Cr2O3的氧化层，进一步提高了封孔涂层的抗热腐蚀性能。结论 封孔层提高了涂层致密性，能有效抑制腐蚀介质在热喷涂涂层中的扩散，封孔能明显提高Inconel625涂层的抗热腐蚀性能。

The work aims to seal the thermal spray coating with sealant, and study effect of sealing on the thermal corrosion resistance of the coating to improve the corrosion resistance of thermal spray coatings in severe environments in view of that the existence of pores and defects in thermal spray coatings is one of the important reasons for coating failure. Inconel 625 coating was prepared on 20# steel substrate by high velocity oxygen fuel spray deposition. The sealing agent was prepared with TEOS as the sealing agent base material and Cr2O3, Al2O3, ZrO2 and CeO2 as fillers. Then, the sealing agent was used to seal the pores existed in the Inconel625 coating. The effect of sealing agent on corrosion resistance of coating was studied and the coatings with and without sealing agent were corroded in film of mixed salts 75wt%Na2SO4+25wt%NaCl (mass fraction) at 650 ℃, and the change of sample mass was obtained at intervals during the test to study the corrosion kinetic. The compositions, structures and morphologies of corrosion products were investigated by XRD, SEM and EDS. For unsealed Inconel 625 coating, the gained mass was about 4.4 mg/cm2 after 160 h. The unsealed Inconel 625 coating had a duplex microstructure and the outer Ni-rich layer was looser and porous, and the inner Cr-rich layer was compact. Meanwhile, the S element was detected at the coating/corrosion interface. For sealed Inconel 625 coating, the mass loss was about 0.45 mg/cm2 after 160 h because the sealing agent dissolved in the molten salt during the corrosion process. During the corrosion process, Ni diffused in the sealing layer and oxidized to fill the defects of the sealed layer. A Cr2O3-rich oxide layer formed at the coating/sealed layer interface, and then further improved the hot corrosion resistance of the sealed coating. The sealant improves the compactness of the coating and effectively inhibits the diffusion of corrosive media in the thermal spray coating. Then, the hot corrosion resistance of Inconel 625 coating is improved obviously through sealing.