MnO_2添加剂对镍铁尖晶石基惰性阳极耐腐蚀性的影响

Effect of MnO_2 Addition on Corrosion Resistance of Nickel-Ferric Spinel Based Inert Anode

以氧化物NiO和Fe2O3为原料,添加氧化物MnO2,采用高温固相烧结法制备了NiFe2O4基惰性阳极材料,采用失重法测量了阳极试样的静态热腐蚀速率,并对其腐蚀机理进行了初步探讨.实验结果表明,添加2%(ω)MnO2粉末的惰性阳极试样的静态热腐蚀速率最低.由于掺杂的MnO2在晶界处富集,熔盐对晶粒的腐蚀首先在晶界处发生反应生成Mn2AlO4相,而Mn2AlO4相结构致密,冰晶石熔盐通过该相向NiFe2O4尖晶石晶粒内扩散速度减慢,从而降低了腐蚀速率.

The NiFe2O4 inert anode was synthesized by high temperature solid-state reaction sintering method using NiO and Fe2O3 as main raw materials and adding MnO2 powder. The static thermal corrosion rates of inert anode samples were measured by weightloss, and the corrosion mechanism was discussed. The experimental results indicate that the static thermal corrosion rate of the sample added with 2%(ω) MnO2 powder is the lowest. Because MnO2 dopant enriches at crystal boundary, the corrosion reaction of molten salt to crystal grains occurs firstly at the crystal grain boundary, and forms MnAl2O4 phase, which is dense and prevents the cryolite molten salt to penetrate into the inert anode, thus reducing the corrosion.