【作者】 高晓宝；

【导师】 刘宁；

【作者基本信息】 合肥工业大学 ， 材料学， 2006， 硕士

【摘要】 自从1994年Ishihara和Goodenough发现Sr,Mg掺杂的LaGaO₃具有较高的氧离子电导率以来,很多科研工作者对这一新型电解质材料进行了研究,研究表明Sr,Mg掺杂的LaGaO₃（LSGM）基钙钛矿型氧化物在中温（600～800℃）和较宽的氧分压范围内呈现出较高的氧离子电导率和稳定性,是一种很有发展前途的中温电解质材料。但是在实际应用中,人们发现较差的力学性能导致这种材料难以得到广泛的应用。Yasuda等人的研究表明,在LaGaO₃基体中分散加入2wt%氧化铝可以在不降低电解质的电导率的同时大幅度的提高材料的机械性能。本文在此基础上,用不同粒度的氧化铝分散加入到基体中,并分别与没加氧化铝的材料进行比较,研究加入的氧化铝的粒度对力学性能提高的影响,并对材料的显微组织分析进行了分析。 本课题通过固相反应法制备了LSGM1520粉体,在其中均匀掺杂两种粒度的氧化铝,最终烧结制得电解质材料。对所制备的材料进行XRD物相分析,采用扫描电镜进行显微组织分析和能谱分析。此外,研究了材料的抗弯强度、断裂韧性和硬度。 XRD分析结果显示,三种材料都为两相结构（LaGaO₃+LaSrGa₃O₇）。氧化铝的添加使得杂相的含量略有增加,氧化铝进入了主相和杂相晶格之中。对所制备的材料进行SEM分析可知,添加细氧化铝材料的晶粒尺寸最小,相分布最为均匀,未添加氧化铝材料的晶粒粗大,杂相分布偏析,添加粗氧化铝的材料的显微结构介于两者之间。对应的添加细氧化铝材料的抗弯强度最高,粗氧化铝添加的抗弯强度次之,未添加氧化铝材料的抗弯强度最差。更多还原

【Abstract】 Sr- and Mg-doped lanthanum gallate（LSGM） first synthesized by Ishihara and Goodenough appears high oxygen ionic conductivity, which has been widely investigated by many scientists. The results show that Sr- and Mg-doped LaGaO₃ was one of the most promising electrolyte candidates for intermediate-temperature solid oxide fuel cells because of its high and exclusive oxygen ionic conductivity at 873-1073K and excellent stability over a broad range of oxygen partial pressure. But the weak mechanical properties of these LaGaO3 -based materials limited their practical application. As was pointed out in Isamu Yasuda’s paper, the mechanical strength has been greatly improved without deleteriously affecting conductivity by dispersing 2wt% alumina into the matrix of LSGM. Then in this work, the effects of alumina with different particulate size dispersion on mechanical properties were investigated.In this work, the powder of Sr- and Mg-doped LaGaO₃ material was prepared by conventional solid state reactive firing, alumina with 7μm and 200nm was dispersed respectively. Room-temperature X-ray diffractometry was performed on the sintered samples , the surface and fracture surface of specimen were observed by SEM. Fracture strength , fracture toughness and hardness were researched.The phase structure of three materials were two-phase region, cubic-perovskite and LaSrGa₃O₇, determined from XRD. The weight ratio of LaSrGa₃O₇ increases a little with the alumina dispersion. Alumina was dissolved into crystal lattice of LSGM. The grain size of electrolyte material dispersed with sub-micron alumina was minimum, the value of material dispersed with micron alumina was medial and the grain size of material without alumina was maximum.更多还原