MgO-Mg_2TiO_4复相材料的制备及其抗电解质侵蚀研究

Preparation of MgO-Mg_2TiO_4 composite and its corrosion resistance to electrolyte

在轻烧氧化镁粉(粒度≤45μm)中分别添加0、1%、2%、5%、10%(w)的化学纯TiO2,经球磨混合、干压成型后,分别在1 400、1 500和1 600℃保温3 h反应烧结,然后检测试样的显气孔率、体积密度和抗AlF3-Na3AlF6-K3AlF6侵蚀性,并分析其物相组成和显微结构。结果表明:1)采用反应烧结法可以制备MgO-Mg2TiO4复相材料。随着TiO2添加量从0增加到5%(w),试样致密化程度明显提高,同时Mg2TiO4生成量逐渐增多,氧化镁晶粒逐渐长大;添加10%(w)TiO2的材料,由于生成Mg2TiO4较多,体积膨胀较大,其致密度比添加5%(w)TiO2的略低。2)随着TiO2添加量从0增加到5%(w),由于材料致密度提高以及化学稳定性好的Mg2TiO4分布于方镁石晶粒周围,因此MgO-Mg2TiO4复相材料抗AlF3-Na3AlF6-K3AlF6侵蚀性逐渐提高;由于添加10%(w)TiO2的材料的致密度比添加5%(w)TiO2的低,因而抗侵蚀性稍差。

MgO-Mg2TiO4 composite was prepared by adding chemically pure TiO2 （0, 1 % ,2% ,5% and 10% in mass） in light-burned magnesia （particle size ≤45μm） ,ball milling ,dry pressing ,and reaction sintering at 1 400,1 500 and ] 600 ℃ for 3 h, respectively. Apparent porosity, bulk density and corrosion resistance to AIF3-Na3AIF6-K3AIF6 were investigated. Phase composition and microstructure were analyzed. The results show that： （1）MgO-Mg2TiO4 composite can be synthesized by reaction sintering;with TiO2 addition in- creasing from 0 to 5%, the specimen is denser obviously accompanying with more Mg2TiO4 forming and MgO grains growing;the specimen with ：10% TiO2 obtains a slightly lower density than that with 5% TiO2 due to larger volume expansion resulting from the formation of more Mg2TiO4; （2）with TiO2 addition in- creasing from 0 to 5%, corrosion resistance to AIF3-Na3AIF6-K3AIF6 of the specimens improves gradually owing to the density increase and the Mg2TiO4 possessing good chemical stability distributing along peri- clase grains;compared with the specimen with 5% TiO2 ,that with 10% TiO2 owns a little worse corrosion re- sistance because of lower density.