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ZrO_2系陶瓷在结构陶瓷中占有重要地位。为了获得性能优异的ZrO_2陶瓷,须获得高纯,超细,少团聚以及结构可以控制的ZrO_2粉体。Srinivasan和沈志坚等人的研究认为,沉淀过程pH值影响了水合氧化锆凝胶的结构,进而影响了凝胶热分解后ZrO_2和Y_2O_3(MgO)-PSZ的相组成。戴健和仇海波等人的研究还表明通过控制沉淀过程pH值可以获得无团聚,甚至单球分散状的ZrO_2纳米粉。此外,韩利成等人的研究认为,残留Cl~-、NH_4~+离子使干凝胶中非架桥羟基数量增加,导致粉末产生硬团聚体。朱宣惠,Dole等人的研究认为,通过水洗去除Cl~-、NH_4~+离子,再经有机溶剂脱水减少表面张力,可以防止硬团聚的产生。可见在用液相沉淀法制备ZrO_2纳米粉时,沉淀过程的pH值以及NH_4Cl的存在(Cl~-、NH_4~+)对ZrO_2超细粉的相结构以及团聚状态都有重要影响。因此研究pH值,清洗工艺对其析晶过程的影响具有十分重要的意义。
ZrO2-based ceramics occupy an important position in structural ceramics. In order to obtain excellent performance ZrO 2 ceramics, it is necessary to obtain ZrO 2 powders with high purity, fineness, less agglomeration and structure controllable. Srinivasan and Shen Zhijian et al.'s study suggest that the pH value of the precipitation process affects the structure of the hydrated zirconia gel, which in turn affects the phase composition of the ZrO 2 and Y 2 O 3 (MgO) -PSZ after thermal decomposition of the gel. Dai Jian and Qiu Haibo and others also showed that by controlling the pH value of the precipitation process can be obtained without agglomeration, or even single-ball dispersion of ZrO2 nano-powder. In addition, a study by Han Lee-Sung et al. Suggests that residual Cl ~ -, NH_4 ~ + ions increase the number of non-bridging hydroxyl groups in the xerogel, leading to hard agglomerates of the powder. Zhu Xuanhui, Dole et al.'s study suggests that the removal of Cl ~ - and NH_4 ~ + ions by water washing and the reduction of surface tension by organic solvent dehydration can prevent the occurrence of hard agglomeration. It can be seen that the pH value of precipitation process and the presence of NH_4Cl (Cl ~ -, NH_4 ~ +) have an important effect on the phase structure and agglomeration state of ZrO_2 superfine powders when preparing ZrO_2 nano-powders by liquid-phase precipitation. Therefore, it is very important to study the influence of pH value and cleaning process on its crystallization process.