氧化钪稳定氧化锆粉体材料制备过程研究

发布时间：2018-07-03 07:19

  本文选题：氧化 + 稳定　； 参考：《北京有色金属研究总院》2014年硕士论文

【摘要】：氧化钪稳定氧化锆(ScSZ)具有优良的氧离子传导性能,已经成为中温固体氧化物燃料电池(SOFC)首选的新型电解质材料。近年来,随着美国、日本在中温SOFC的技术发展,推动了对ScSZ粉体的应用。目前,国内外对ScSZ粉体制备技术的研究报道较少,商业化的粉体主要由日本第一稀有元素公司提供,而国内产品存在电导率低、批次不稳定等缺点。因此,开展高性能ScSZ粉体材料制备及其合成过程机理研究具有重要意义。 本文选择易于工业化的氯化物体系,采用共沉淀法合成ScSZ前驱体,分别研究了微波水热法及高温分解法后处理过程对ScSZ目标粉体性能的影响。主要研究内容及结果如下： (1)研究了pH值对锆化合物沉淀过程的影响,结果表明随着pH值增加,粉体的硬团聚现象逐渐增加,但在高pH条件下沉淀得到的粉体一次粒径的均匀性较好。 (2)研究了pH值对钪化合物沉淀体系的影响,结果表明pH值较低时,Cl-参与反应生成的Sc(OH)2.6Cl0.4-H20结构阻碍前驱体γ-ScOOH.nH2O薄片的生长,随着pH值的增加该影响逐渐减弱。 (3)为了得到均匀的钪锆铈共沉淀粉体,研究了钪锆铈混合沉淀体系的Zeta电位变化规律,并结合该体系的Ksp,确定合理的混合体系沉淀pH值为8-9之间。利用在线颗粒分析系统FBRM和PVM对共沉淀过程进行实时图像及粒径分析,发现在常温条件下反应体系主要发生无定形沉淀。同时研究了高温陈化对反应体系中的晶体生长的影响,发现高温条件下晶体呈一维方向生长,但晶体结构不稳定,烘干后晶体坍塌转为无定型态。 (4)研究了微波水热法和高温分解法对ScSZ前驱体进行后处理研究。高温分解研究结果表明,煅烧温度为420℃～1000℃区间均可获得立方相结构,通过球磨后该粉体的粒径小且分布均匀,压制陶瓷片的电导率为170.50ms/cm,通过二次焙烧处理后,电导率进一步提高到180.25ms/cm。微波水热条件试验表明,在水热温度为150℃、水热时间为2.5h、添加矿化剂下制备出结晶度好、比表面积高的粉体,其中值粒径Dso为6.1pmm,粒径分布(D90-D1o)/2D5o为1.0,压制陶瓷片的电导率为125.65ms/cm,低于高温分解球磨后的粉体,不过从能耗方面考虑,微波水热法仍具有一定的发展潜力。
[Abstract]:Scandium-stabilized zirconia (ScSZ) has become the preferred electrolyte material for medium temperature solid oxide fuel cells (SOFC) due to its excellent oxygen ion conductivity. In recent years, with the development of medium temperature SOFC technology in America and Japan, the application of ScSZ powder has been promoted. At present, there are few reports on the preparation technology of ScSZ powder at home and abroad. The commercial powder is mainly supplied by the first rare element Company of Japan. However, the domestic products have the disadvantages of low conductivity and unstable batch. Therefore, it is of great significance to study the preparation and synthesis mechanism of high performance ScSZ powder. In this paper, ScSZ precursor was synthesized by coprecipitation method in chloride system which is easy to industrialize. The effects of microwave hydrothermal method and high temperature decomposition process on the properties of ScSZ target powder were studied. The main contents and results are as follows: (1) the effect of pH value on the precipitation process of zirconium compounds is studied. The results show that the hard agglomeration of powders increases with the increase of pH value. However, the uniformity of the primary particle size of the powders obtained by precipitation at high pH was better. (2) the effect of pH value on the precipitation system of scandium compounds was studied. The results show that the SC (OH) 2.6Cl0.4-H20 structure of the precursor 纬 -ScOH.nH2O is hindered when pH value is low. (3) in order to obtain homogeneous Scandium zirconium cerium coprecipitation powder, the growth of precursor 纬 -ScOH.nH2O wafer is gradually weakened with the increase of pH value. The Zeta potential of the mixed precipitation system of scandium zirconium and cerium was studied and the pH value of the mixed system was determined to be between 8-9. The real-time image and particle size analysis of the coprecipitation process were carried out by using the on-line particle analysis systems FBRM and PVM. It was found that the amorphous precipitation occurred mainly in the reaction system at room temperature. At the same time, the effect of aging on the crystal growth in the reaction system is studied. It is found that the crystal grows in one-dimensional direction at high temperature, but the crystal structure is unstable. The crystal collapses into an amorphous state after drying. (4) the microwave hydrothermal method and the high temperature decomposition method were studied for the post-treatment of ScSZ precursor. The results of high temperature decomposition show that the cubic phase structure can be obtained at the range of 420 鈩，

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