凝胶浇注法制备Ni/TiO_2-Ce_(0.8)Sm_(0.2)O_(1.9)多孔阳极材料的研究

Gel-cast Ni/TiO_2-Ce_(0.8)Sm_(0.2)O_(1.9) cermet as anode materials for solid oxide fuel cells

以硝酸盐和氧化物为原料,通过凝胶浇注法制得了摩尔分数为10%TiO2-Ce0.8Sm0.2O1.9(TiO2-SDC)粉体,采用X射线衍射、透射电镜对粉体的相组成和颗粒形貌进行了分析。结果表明,干凝胶在600℃下煅烧后,TiO2和Sm2O3能完全固溶进CeO2晶格中,形成具有单一立方相结构和纳米粒度的TiO2-SDC粉体;凝胶浇注法和机械混合法制备的成形坯在1 300℃下烧结所得NiO/TiO2-SDC烧结体的孔隙率分别为31.0%和19.0%,还原后Ni/TiO2-SDC材料的孔隙率分别为36.4%和23.0%。SEM观察表明,凝胶浇注法制备的NiO/TiO2-SDC烧结体和Ni/TiO2-SDC金属陶瓷的微结构更加疏松,两相颗粒分布更为均匀;在测试温度范围内,凝胶浇注法制备的Ni/TiO2-SDC阳极材料的电导率明显高于由机械混合法制备的Ni/TiO2-SDC材料,773 K下两者的电导率分别为648 S/cm和430 S/cm。

TiO2 doped Ce0.8Sm0.2O1.9（TiO2-SDC） powder was prepared from the corresponding nitrates and oxides by a gel-casting method. Phase composition and particle size and shape of the powder were investigated by XRD and TEM. It was shown that nanosized TiO2-SDC powder with single cubic phase structure can be obtained by calcining the dried gels at a relatively low temperature-600 ℃. Microstructure observation shows that NiO/TiO2-SDC ceramics and Ni/TiO2-SDC cermet fabricated from the gel cast NiO/TiO2-SDC powder have more uniform and finer grain and pore size than those from the mechanically mixed NiO/TiO2-SDC powder. Furthermore, Ni/TiO2-SDC cermet prepared from the gel cast NiO/TiO2-SDC composite shows higher electrical conductivity than that of Ni/TiO2-SDC cermet from the mechanically mixed NiO/TiO2-SDC powder,and at 773 K in H2, their conductivity is 648 S/cm and 430 S/cm, respectively.