Abstract: The main reason for the damage of refractories is the penetration and corrosion by alkali ions such as K⁺ and Na⁺ in chemical waste liquid. Effective inhibition of alkali melt penetration is helpful to improve the service life of heat treatment equipment, but the method of simply reducing porosity may deteriorate its thermal shock stability. In this paper, the wetting, corrosion and penetration processes of refractories by Na₂CO₃ melt were studied, and the difference of alkali penetration resistance of different refractories was discussed from the point of view of wettability. Therefore, three types of mullite (high purity sintered mullite, fused mullite and ordinary sintered mullite), andalusite and clay were used as raw materials to prepare refractories by mechanical press forming and high temperature sintering. The alkali corrosion experiment was carried out at 900 ℃ by static crucible method with Na₂CO₃ as alkali corrosive agent. The phase and microstructure of the specimens before and after alkali corrosion were analyzed by X-ray diffractometer and scanning electron microscope, and the wettability of alkali melt to different substrates was tested. The results show that all materials are not damaged, showing excellent corrosion resistance. The ability of each group of specimens to resist the penetration of Na₂CO₃ melt is different. The specimens prepared by high purity sintered mullite have the best corrosion and penetration resistance, while the specimens prepared by fused mullite and ordinary sintered mullite have poor penetration resistance, which is related to the wetting ability of Na₂CO₃ melt to them. In this experiment, the difference of alkali corrosion resistance between refractories is analyzed from the perspective of high temperature wettability, which provided a new idea and theoretical basis for the research and production of aluminum-silicon refractories with excellent corrosion resistance.

Key words: refractory, mullite, Na₂CO₃ melt, wettability, corrosion, penetration