Effect of MnO2 on the electrical conductivity of ZrO2

Electrical conductivity of ZrO₂ doped with MnO₂ has been measured at various temperatures for different molar ratios. The conductivity increases due to hopping of oxygen into neighboring vacancies, created by doping. Increase in temperature increases the rate of hopping, which results in the rise in conductivity and after attaining a maximum the conductivity, decrease due to collapse of the fluorite framework. All compositions show phase transition in ZrO₂ from monoclinic to tetragonal at 746 K. The XRD, DTA, and FT-IR studies were carried out for confirming the doping effect and transition in ZrO₂. The text was submitted by the authors in English.     

Y2O3添加剂对ZrO2超微粉体性质的影响

添加0-6mol%Y2O3的ZrO2超微粉体由化学共沉淀法制备，系统地研究了添加剂对粉体粒子粒径，表面性质和团聚状态的影响，结果表明，添加Y2O3组元，使制备的ZrO2粉体粒子粒径减小，对粒子的长大趋势可起到抑制作用，但加剧了粉体粒子的团聚，团聚体颗粒变大，团聚强度升高，随着组元添加量的增多，作用加剧。     

Effect of Catalytic Alcohol Conversion on the Mechanical Strength of Porous ZrO2 and ZrO2 + Y2O3 Materials

The surface and bulk properties of ZrO₂ and ZrO₂ + Y₂O₃ powder compacts are studied by x-ray diffraction, x-ray electron spectroscopy, electron spin resonance, and Raman scattering spectroscopy. Heat treatment in air at 450–800°C and catalytic conversion of methanol and ethanol on the surface of the compacts are found to have a significant effect on their mechanical strength. The results offer some insight into the nature of surface diffusion, which reduces the area of intergranular contacts, thereby raising the mechanical strength of the material, and provide indirect evidence that similar molecular mechanisms underlie the strengthening of metal and oxide powder compacts by heat treatment and catalytic reactions.     

Effect of Processing Route on the Stability of Aqueous ZrO2 suspensions

The relationship between processing route and suspension stability in ZrO2-H2O-PANH4 system was investigated through rheology study. The work showed that two suspensions with identical PAN H4 concentration and final solution condition but prepared by different routes differed greatly in stability. This behavior is attributed to their different distribution state of PANH4 on ZrO2 surface that is determined by the adsorption affinity depending on pH condition in solution. High affinity at pH 5.0 induces a nonuniform distribution of soluble PAA- （polyacrylicacid） on particle surface, which can flocculate the suspension strongly, while low affinity at pH 9.0 induces an uniform distribution of polymer so that the higher stabilization can be achieved. A simple mathematical model was used to account for the observed results.     

Effect of ZrO2 addition on the mechanical properties of porous TiO2 bone scaffolds

This study aimed at the investigation of the effect of zirconium dioxide (ZrO₂) addition on the mechanical properties of titanium dioxide (TiO₂) bone scaffolds. The highly biocompatible TiO₂ has been identified as a promising material for bone scaffolds, whereas the more bioinert ZrO₂ is known for its excellent mechanical properties. Ultra-porous TiO₂ scaffolds (> 89% porosity) were produced using polymer sponge replication with 0–40 wt.% of the TiO₂ raw material substituted with ZrO₂. Microstructure, chemical composition, and pore architectural features of the prepared ceramic foams were characterised and related to their mechanical strength. Addition of 1 wt.% of ZrO₂ led to 16% increase in the mean compressive strength without significant changes in the pore architectural parameters of TiO₂ scaffolds. Further ZrO₂ additions resulted in reduction of compressive strength in comparison to containing no ZrO₂. The appearance of zirconium titanate (ZrTiO₄) phase was found to hinder the densification of the ceramic material during sintering resulting in poor intergranular connections and thus significantly reducing the compressive strength of the highly porous ceramic foam scaffolds.     

ZrB2对浸入式水口用ZrO2-C材料性能的影响

浸入式水口渣线材料性能的优劣决定着连铸安全和效率的高低,为提高浸入式水口渣线的性能,本研究在ZrO2-C材料中加入ZrB2,探讨ZrB2对ZrO2-C材料性能尤其是抗侵蚀性的影响.结果表明:ZrB2添加到ZrO2-C材料中后,会显著提高材料的抗氧化性,其机理是高温下ZrB2生成B2O3,B2O3在高温下为液相,堵塞气孔,大幅度减缓氧化.适量ZrB2添加到ZrO2-C材料中后,可以提高材料的抗侵蚀性.但ZrB2容易在CO气氛下生成B2O3,B2O3易使氧化锆脱溶、分解,加速ZrO2-C材料的侵蚀.     

The ZrO2-rich region of the ZrO2-MgO system

The solubility limits of MgO in tetragonal zirconia were studied by combining the differential thermal analysis data and X-ray disappearing phase method. From these experiments a eutectoid reaction, tetragonal ZrO₂ solid solution monoclinic ZrO₂ solid solution + MgO, at 1120±10 °C and 1.6±0.2 mol% MgO was established. The solubility of MgO in tetragonal ZrO₂ diminished as the temperature increased, and at 1700 °C the solubility was less than 0.5 mol% MgO. The extent of the cubic zirconia solid solution single field was determined by using precise lattice parameter measurements and SEM observations. In this way an invariant eutectoid point, cubic ZrO₂ solid solution tetragonal ZrO₂ solid solution + MgO, was located at 1420±10 °C and 14.8±0.5 mol% MgO.     

Effect of ZrO2 inclusions on fracture properties of MgCr204

The effects of unstabilized ZrO₂ inclusions on the strength, fracture surface energy and thermal-shock resistance of MgCr₂O₄ have been evaluated. The fracture surface energy for MgCr₂O₄-ZrO₂ composites was observed to depend on the agglomerate particle size distribution, and volume fraction of the ZrO₂ inclusions. Large, nonuniformly distributed ZrO₂ inclusions tended to produce a relatively small increase in the fracture surface energy of MgCr₂O₄. The fracture surface energy increased with increasing ZrO₂ content to a maximum value of 24.5J m^–2 at 16.5 vol % ZrO₂, and decreased as the ZrO₂ content increased further. It is proposed that this four-fold increase in fracture surface energy results from the absorption of energy due to microcrack formation in the MgCr₂O₄ matrix, which results primarily from the tensile stresses due to the tetragonal monoclinic phase transformation of ZrO₂ and the associated volume expansion. The improvement in mechanical properties, specifically the four-fold increase in fracture surface energy, resulted in a substantial increase in thermal-shock resistance of MgCr₂O₄-ZrO₂ composites as indicated by the results of thermal-shock experiments.     

表面活性剂对Cu-H_2O和ZrO_2-H_2O纳米流体稳定性的影响

通过添加表面活性剂制备了Cu-H2O和Zr O2-H2O纳米流体,研究了十二烷基苯磺酸钠、十六烷基三甲基溴化铵和辛基苯基聚氧乙烯醚等表面活性剂对Cu-H2O和Zr O2-H2O纳米流体分散稳定性的影响;并利用分子动力学方法计算出不同表面活性剂分子与Cu/Zr O2颗粒表面的相互作用能。结果发现添加表面活性剂可较大程度地提升纳米流体的稳定性,而尤以添加十二烷基苯磺酸钠的效果最为明显,计算结果也显示十二烷基苯磺酸钠分子与Cu/Zr O2间的吸附作用最强。此外,还模拟了SDBS与Cu-H2O纳米流体中Cu颗粒的吸附行为。     

Effect of agglomerates in ZrO2 powder compacts on microstructural development

Ultrafine zirconia powders were prepared by a coprecipitation and spray-drying method. Agglomerates may be fragmented or present in green bodies after compaction. The effect of agglomerates on sintering and microstructural development was studied and it was found that the agglomerate content in compacts was a major factor affecting the microstructure development and the sintered densities. The interaction between agglomerates themselves, and between agglomerates and the primary particle matrix is discussed. It is argued that the hard agglomerates in the powder from the water-washed coprecipitates are formed by oxobridging between non-bridging hydroxyl groups present in the zirconium hydroxide structures due to the effect of hydrogen bonding in the aqueous system. The substitution of organic -OR groups for the non-bridging hydroxyl groups removes this hydrogen-bonding effect between the zirconium hydroxide units and thus eliminates the cause of agglomeration.     

Solid solutions of metastable tetragonal ZrO2 and Ce3ZrO8 in the system ZrO2-CeO2

In the system ZrO₂-CeO₂, metastable t-ZrO₂ solid solutions containing up to 30 mol% CeO₂ crystallize at temperatures of 385–430 °C from amorphous materials prepared by the hydrazine method. Crystalline Ce₃ZrO₈ solid solutions are formed in as-prepared powders between 30–75 mol % CeO₂. The variation of the lattice parameters of both solid solutions is determined as a function of CeO₂ content. The value of the lattice parameter of pure Ce₃ZrO₈ (cubic) is a = 0.5342 nm. Detailed characterization of the Ce₃ZrO₈ powder has been performed. Crystallite size and particle size are strongly dependent on the heating temperature. Specific surface areas do not drop below 40 m²g^–1 until the heating temperature is above 1000°C.     

Effect of ZrO2 on conductivity of PVC-PMMA-LiBF4-DBP polymer electrolytes

The preparation and characterization of composite polymer electrolytes of PVC-PMMA-LiBF₄-DBP for different concentrations of ZrO₂ have been investigated. FTIR studies indicate complex formation between the polymers, salt and plasticizer. The electrical conductivity values measured by a.c. impedance spectroscopy is found to depend upon the ZrO₂ concentration. The temperature dependence of the conductivity of the polymer films seems to obey the VTF relation. The conductivity values are presented and results discussed.     

亚微米ZrO_2粉体对氧化铝陶瓷力学性能的影响

在高纯Al2O3粉体中添加质量分数为16%的亚微米ZrO2粉体,制备Al2O3-ZrO2复合粉体,通过X射线衍射仪、电子探针和扫描电子显微镜分别对样品的相组成和显微结构进行分析,研究不同烧结温度下亚微米ZrO2粉体对氧化铝陶瓷抗折强度和硬度的影响。结果表明,在1 450℃时无压烧结2 h,Al2O3-ZrO2复相陶瓷的晶粒粒径约为0.5μm,抗弯强度高达797 MPa,提高了46%,维氏硬度为17.9 GPa。     

铂修饰LSM电极对ZrO2氧敏特性的影响

以固相反应合成La0．7Sr0．3MnO3和YSZ，采用密封材料封装烧结LSM和YSZ，丝网印刷LSM作电极，制备极限电流型氧传感器。在500℃测试氧敏元件极限电流随氧气浓度变化的响应。测试结果表明，LSM电极经Pt修饰后，提高了氧敏元件信号的稳定性，与相同条件制备的Pt电极信号差别不大。     

沉淀法制备条件对ZrO_2纳米微粒性质的影响

综述了国内外沉淀法制备纳米ZrO2微粒的条件控制及相应的产品性质,综合分析了制备过程中锆盐浓度、稳定剂盐(Y3+、Mg2+、Ca2+、Ce4+等)的浓度及种类、pH值、沉淀处理和热处理等操作对产品性质的影响,并总结了相应的影响机理;根据材料科学发展方向及市场要求,对ZrO2纳米微粒制备领域研究的重点和热点进行了展望。     

过渡层ZrO2对不同沉积厚度TiO2薄膜结构的影响

TiO2作为高介电常数材料已被广泛研究.为了防止TiO2与Si基底发生反应,在Si与TiO2之间加入与TiI2结构相似热稳定性好的ZrO2作为过渡层.改变TiO2薄膜厚度,并在900℃对薄膜进行1h退火处理.通过XRD分析显示,随着TiO2厚度减小,各衍射峰强度逐渐降低,但各峰位及其相对强度无明显变化.通过SEM可以发现,热处理前各薄膜均无裂纹和孔洞.热处理后,TiO2厚度为150m及80nm的薄膜平整光滑无裂纹孔洞,晶粒排列致密晶界清晰,当TiO2厚度降为30nm时,薄膜仍平整光滑,只在晶界上出现因热处理而产生的缩孔.