On the Modification of Hydration Resistance of CaO with ZrO2 Additive

Various ZrO₂/CaO samples were fabricated by cold isostatic pressing and sintered at 1750°C for 4 h. It was observed that the sample with 12% ZrO₂ additive possessed the good hydration resistance and had the lowest apparent porosity of about 0.75%; its weight additive stored after 56 days was less than 0.6 wt%, and it contributed to the occurrence of CaZrO₃ on the surface of CaO. The CaO crucible with 12 mol% ZrO₂ additive did not react with titanium melt during melting TiNi alloy. This provides a support for searching a new refractory with the good hydration resistance for induction melting titanium alloys.     

溶胶-凝胶法制备氧化锆粉体

以正丙醇锆为锆源,采用溶胶-凝胶法制备了ZrO2粉体。研究了硝酸含量对凝胶时间及热处理温度对ZrO2晶型的影响规律。通过控制硝酸含量可以有效改变凝胶时间;通过锆醇盐水解缩聚制备的ZrO2干凝胶,在低温下热处理首先形成ZrO2四方相,在较高温度热处理后才转变为单斜相;锆醇盐水解缩聚制备的氧化锆粉体在1200℃以后烧结过程明显加快。     

Phase formation during crystallization of a Li2O-Al2O3-SiO2 glass with ZrO2 as nucleating agent – An X-ray diffraction and (S)TEM-study

Glass ceramics based on the system Li₂O/Al₂O₃/SiO₂ (LAS) often show a coefficient of thermal expansion close to zero. Although these glass-ceramics are of high economic importance, the fundamentals of the crystallization process are still not fully understood. In this paper, the effect of ZrO₂ addition as a sole nucleation agent on the crystallization of the LAS glass is described predominantly using transmission electron microscopy and X-ray diffraction. The composition of the studied green glass was close to that of the commercially available Robax™ glass (Schott AG), which, however, contained both, ZrO₂ and TiO₂ as nucleating agents. It was found that during thermal treatment, in a first step, already at temperatures around 10–20 K below the glass transition temperature, T_g, ZrO₂ nanocrystals with sizes in the range from 5 to 15 nm were precipitated. The next crystalline phase that forms during the crystallization process was LAS with a structure similar to the hexagonal high temperature phase of quartz. These crystals were much larger than the ZrO₂ crystals. If thermal treatment was carried out at higher temperatures, a dense network of LAS crystals was formed. Differently shaped crystals in samples with different thermal history were visualized, and an enrichment of Ba and Sb in the residual glass phase in the late stages of thermal treatment was found. Also, an enrichment of aluminum around the ZrO₂ crystals was evident, which is a hint at a preceding droplet phase separation from which the ZrO₂ crystals were precipitated. The crystallization is notably different from that of mixed ZrO₂/TiO₂ nucleating agents used in commercial lithium alumosilicate glass ceramics.     

影响CaCl2-NaCl熔盐电脱氧法制备金属Zr的工艺条件

将氧化物转化为金属是熔盐电解精炼干法后处理氧化物乏燃料流程的关键步骤之一。在等摩尔CaCl₂-NaCl混合熔盐体系中，以石墨棒为阳极，采用高温烧结后的ZrO₂模拟UO₂开展了电脱氧制备金属Zr的FFC剑桥工艺条件优化。研究了工艺条件（槽电压、电解时间、烧结温度和电解温度等）对电脱氧制备Zr的影响。采用场发射扫描电子显微镜(SEM)和X射线衍射(XRD)分别分析了电解前后ZrO₂阴极的微观结构和物相组成。优化后的工艺条件为：电压3.4 V、电解时间12 h、烧结温度900 ℃和电解温度722 ℃。同时，研究结果表明, ZrO₂电脱氧还原为Zr时，存在中间产物CaZrO₃和ZrO。     

Pt-NbOx/C、Pt-ZrO2/C复合氧电极催化剂的制备及性能研究

以NbOx、ZrO2作为助催化剂,采用分步法制备得到Pt-NbOx/C、Pt-ZrO2/C复合催化剂,采用XRD、SEM等手段分析了催化剂的物相及形貌特征。通过循环伏安法、阴极极化曲线等电化学方法对催化剂的电化学性能进行了研究。结果表明,Pt均匀分布在载体表面,颗粒大小均在5 nm以下;NbOx和ZrO2的加入没有改变氧的还原反应机理,与Pt/C、Pt-ZrO2/C催化剂相比,Pt-NbOx/C复合催化剂催化氧电化学还原过程的活性有了明显提高。     

低温陈化法制备纳米ZrO2及条件对粒径的影响

为了制得可控粒径的ZrO2粉并提高其均匀性,采用低温陈化法合成了ZrO2纳米粉,并讨论了反应条件对样品粒径的影响.通过DTA,XRD,TEM和粒度分布仪等检测手段对产品进行了表征.结果表明:在500℃得到了晶化较好的单斜相ZrO2,选择适当的合成条件:控制Zr4+与CO(NH2)2的摩尔比为1∶3,溶液pH为1.5,加入少量聚乙二醇800(PEG-800),可得到粒度分布集中,均匀性较好,粒径约为24.4 nm的样品.该法工艺简单、得到的ZrO2粉体粒径分布较窄.     

油酸改性纳米ZrO2粉体及其机制研究

采用水热法制备了平均粒径小于10nm左右的氧化锫.用油酸对纳米ZrO2粉体进行了表面改性,研究了改性工艺条件中油酸添加量对亲油改性效果的影响.按质量百分比油酸:乙醇:水=l:2:2的比例配制改性剂,油酸添加量为ZrO2的lO%(摩尔分数)时,改性的ZrO2粉体在二甲苯中分散稳定性最佳.通过FT-IR分析表明,油酸与纳米ZrO2是以氢键和共价键两种形式结合,在无机纳米粒子表面形成单分子膜.     

ZrW2O8 / ZrO2 可控热膨胀复合材料的制备

采用分步加热固相法成功制备了纯度较高的各向同性负热膨胀材料ZrW₂O₈ 。将ZrW₂O₈ 与ZrO₂ 按一定比例混合, 在1200 ℃烧结24 h 制备了热膨胀系数可控的ZrW₂O₈ / ZrO₂ 复合材料。研究结果表明, 通过改变ZrW₂O₈ 的体积分数, ZrW₂O₈ / ZrO₂ 复合材料的热膨胀系数可以控制为负、正或零。当ZrW₂O₈ 的体积分数为37 %时, 复合材料的热膨胀系数接近零。为了得到致密的ZrW₂O₈ / ZrO₂ 复合陶瓷, 采用Al₂O₃ 作为烧结剂, 取得了较好的效果。0. 35 wt % Al₂O₃ 的加入可以在不影响复合材料热膨胀性能的前提下, 显著提高复合材料的致密度。     

微波辅助合成二氧化锆微粉的研究进展

微波辅助合成是近年来备受国内外研究者关注的制备纳米粉体的新方法。简要介绍了微波辅助合成法及其在无机材料合成方面的应用，综述了微波辅助法合成二氧化锆微粉的研究进展，指出了应用中存在的一些问题，展望了在离子液体中微波辅助合成纳米二氧化锆微粉的应用前景。     

纳米ZrO2应用现状及前景研究

综述了纳米氧化锆在陶瓷增韧、催化作用、传感器以及功能薄膜等领域的应用,由于纳米ZrO2具有超塑性行为,被用作陶瓷增韧的材料;纳米ZrO2的化学稳定性好,粒子尺寸小,比表面积大,使催化性能大大提高;由于纳米ZrO2禁带宽、折射率高,被广泛应用于各种光学薄膜;纳米氧化锆涂层晶粒堆积紧密、气孔率低、涂层的结合性能较好,被广泛用作热障涂层.综合分析认为纳米氧化锆具有十分广阔的应用前景.