Zhao Ying, Cheng Guishi, Xiang Yu, Long Fei, Dong Changqing
National Engineering Laboratory for Biomass Power Generation Equipment, School of the Renewable Energy, North China Electric Power University, Beijing 102206, China.
Department of Mechanical and Material Engineering, Queen's University, Kingston, ON K7L 3N6, Canada.
Materials (Basel). 2018 Nov 6;11(11):2197. doi: 10.3390/ma11112197.
The corrosion of refractories by sodium salts in waste liquid at high temperature has become a serious problem. This paper focuses on the thermodynamic characterization of sodium carbonate (Na₂CO₃) corrosion of six refractories by FactSage modelling in combination with X-ray diffraction (XRD). Three of the refractories are oxides (Fe₂O₃, Al₂O₃, and Cr₂O₃), and the other three are synthetics spinels (magnesium chromium, MgO·Cr₂O₃; magnesioferrite, MgO·Fe₂O₃; and, magnesium aluminium, MgO·Al₂O₃). First, thermodynamic simulations were carried out with the FactSage thermodynamics model using the reaction package to predict the direction of the Na₂CO₃ corrosion reaction in terms of the Gibbs free energy. Then, the reactions between the six refractories and Na₂CO₃ were conducted through a series of refractories/Na₂CO₃ reaction tests. The XRD analytical method was used to describe and understand the chemistry and interpret mineral matter transformation. The products of the tests were also determined by X-ray diffraction and the experimental observations were compared with the results of the thermodynamic simulations. Furthermore, the strength of sodium corrosion of the refractory materials was comprehensively discussed. The results show that MgO·Al₂O₃ has the best thermal stability and it is hard to corrode by Na₂CO₃, while the chrome-containing refractory reacts easily with Na₂CO₃ with a considerably high amount of corrosion product at a temperature of 600 °C. These experimental results are in agreement with the thermodynamic calculations.
高温下废液中钠盐对耐火材料的腐蚀已成为一个严重问题。本文通过FactSage建模结合X射线衍射（XRD），重点研究了碳酸钠（Na₂CO₃）对六种耐火材料的腐蚀的热力学特性。其中三种耐火材料为氧化物（Fe₂O₃、Al₂O₃和Cr₂O₃），另外三种为合成尖晶石（镁铬尖晶石，MgO·Cr₂O₃；镁铁尖晶石，MgO·Fe₂O₃；以及镁铝尖晶石，MgO·Al₂O₃）。首先，使用FactSage热力学模型并结合反应包进行热力学模拟，以根据吉布斯自由能预测Na₂CO₃腐蚀反应的方向。然后，通过一系列耐火材料/Na₂CO₃反应试验，研究了六种耐火材料与Na₂CO₃之间的反应。采用XRD分析方法来描述和理解化学反应，并解释矿物质的转变。试验产物也通过X射线衍射进行测定，并将实验观察结果与热力学模拟结果进行比较。此外，还全面讨论了耐火材料的钠腐蚀强度。结果表明，MgO·Al₂O₃具有最佳的热稳定性，难以被Na₂CO₃腐蚀，而含铬耐火材料在600℃时容易与Na₂CO₃反应，产生大量腐蚀产物。这些实验结果与热力学计算结果一致。
