Hot corrosion behavior of MoSi₂-based coating on Nb alloy exposed to Na₂SO₄ salt was investigated by contrast with the oxidation performance at 1000 °C for 0.5 h, 1 h and 2 h. The phases and microstructures evolutions of the corroded coatings were analyzed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). With the oxidation time prolonging, the profile of splats disappeared gradually. After oxidation for 2 h, SiO₂ particles were generated on the surface of the coating and the mass loss was 1.59 mg/cm², implying that oxidation is a slow degradation process. MoSi₂-based coating exhibited a serious corrosion with Na₂SO₄ salt, forming corroded products such as cristobalite scale and sodium molybdates. With the elongation of corrosion time, the surface morphology of cristobalite layer underwent the transformation from lotus leaves into granules due to basic fluxing of the cristobalite preferentially on the grain boundary. The formed cristobalite scale would spall off due to its loose structure and coefficient of thermal expansion (CTE) mismatch with MoSi₂-based coating, leading to a serious mass loss with 2.5 mg/cm² after hot corrosion for 2 h.

通过在1000°C下0.5 h，1 h和2 h的氧化性能对比研究了MoSi ₂基涂层在暴露于Na ₂ SO ₄盐的Nb合金上的热腐蚀行为。通过扫描电子显微镜（SEM），能量色散谱仪（EDS），X射线衍射（XRD）和X射线光电子能谱（XPS）分析了腐蚀涂层的相和微观结构演变。随着氧化时间的延长，金属片的轮廓逐渐消失。氧化2小时后，涂层表面产生SiO ₂颗粒，质量损失为1.59 mg / cm ²，这表明氧化是一个缓慢的降解过程。MoSi ₂基涂层表现出对Na ₂ SO ₄盐的严重腐蚀，形成腐蚀产物，如方石英鳞片和钼酸钠。随着腐蚀时间的延长，方石英的表面形态发生了从荷叶向颗粒的转变，这是由于方石英的基本通量优先在晶界发生。形成的方石英鳞片由于其松散的结构和与MoSi ₂基涂层的热膨胀系数（CTE）不匹配而散裂，导致热腐蚀2 h后质量损失为2.5 mg / cm ²。