含FeO熔渣对ZrO2固体电解质侵蚀性研究

采用热力学计算软件FactSage中的Equilib平衡计算模块,模拟研究静态条件下SiO2-CaO-Al2O3-MgO-FeO五元渣系对ZrO2材质的侵蚀特性。利用MgO稳定的ZrO2固体电解质管与碳饱和铁液以及酸性渣构建可控氧流电池,分别进行电池在开路条件与外加电势条件下的侵蚀实验,并通过SEM、EDS分析检测,讨论酸性渣可控氧流电解时ZrSiO4新相的形成机理以及对固体电解质导电性能的影响。结果表明,ZrO2的侵蚀程度随温度的升高和渣中FeO含量的增加而增加;在低碱度和高碱度条件下,熔渣与氧化锆之间分别会有ZrSiO4和CaZrO3生成;相对于静态以及开路条件,外加电势电解条件下酸性熔渣与氧化锆之间易形成新相层,从而显著增大电池内阻,阻碍氧离子迁移,但也能减轻或阻碍熔渣对ZrO2固体电解质的渗透侵蚀;可控氧流电解时酸性渣中初始FeO含量最好低于20%,碱度R最好在0.23～0.80之间。

Study on the corrosion of ZrO2solid electrolyte by molten slag containing FeO

The corrosion characteristics of SiO2-CaO-Al2O3-MgO-FeO molten slag system on ZrO2 material were investigated by using the Equilib Module in FactSage software.An electrolytic cell with controlled oxygen flow was constructed by employing MgO partially stabilized ZrO2 solid electrolyte tube,carbon-saturated molten iron and molten acid slag.The corrosion experiments of the cell were carried out under open-circuit and applied voltage conditions,respectively.The results were analyzed by SEM and EDS,and the formation mechanism of ZrSiO4 phase and the effect on conduction performance of ZrO2 solid electrolyte were discussed when the acid slag was electrolyzed with controlled oxygen flow.The results show that,the corrosion of ZrO2 increases along with the increase of temperature and FeO content in molten acid slag;ZrSiO4 and CaZrO3 can be formed between molten slag and ZrO2 under low and high basicity conditions,respectively.In comparison with the static condition and open-circuit condition,the new phase can be easily formed between the molten acid slag and ZrO2 in applied voltage.And the internal resistance of the cell has increased remarkably and the oxygen ion migration is hindered.However the penetration corrosion of molten slag to ZrO2 solid electrolyte can be reduced or prevented.When the molten slag is electrolyzed with controlled oxygen flow,the initial content of FeO in slag should be below 20% and slag basicity should be between 0.23 and 0.80.