Gas corrosion behavior of calcium hexaluminate materials for hydrogen metallurgy

Abstract

Calcium hexaluminate (CA6) has good chemical stability under H2 atmosphere, which indicates its application prospect in the hydrogen metallurgy field. However, iron ores usually contain SiO2 impurities, which can react with H2 to form Si-containing gases such as SiO (g) and SiO2 (g). The Si-containing gases might corrode CA6-based lining refractories during hydrogen metallurgy. The silica and magnetite were heated in a hydrogen furnace to simulate the gaseous environment of hydrogen metallurgy in this paper. At the same time, the corrosion of CA6 materials at elevated temperature (600 °C–1800 °C) under the hydrogen metallurgy atmosphere were studied. In addition, three SiO2 based raw materials (silica, fused silica and waste silica brick) with different SiO2 contents were used to investigate the effect of impurities on the their H2 corrosion. The result showed that SiO2 based raw materials had good chemical stability under H2 atmosphere at the temperature lower than 1200 °C, obvious weight loss appeared at 1400 °C, the impurities including Fe2O3 and MgO would accelerate mass loss under H2 atmosphere. Gases including SiO (g), SiO2 (g) and H2O (g) could react with CA6 to form corundum and yoshiokaite at 1800 °C, which resulted in 3.16% weight gain after heating at 1800 °C for 8 h under the hydrogen metallurgy atmosphere. No significant mass change and mineral phase transformation appeared at the reaction temperature less than 1600 °C.