Thermodynamic assessment of the ZrO2-AlO1.5 system

The ZrO₂-AlO_1.5 quasibinary system has been assessed by means of the CALPHAD (CALculation of PHAse Diagram) technique. The liquid phase, cubic (fluorite-type) zirconia solid solution and tetragonal zirconia solid solution are described by a regular solution model. The monoclinic zirconia and α-AlO_1.5 are treated as stoichiometric phase. A consistent set of optimized parameters describing the system have been obtained to agree with almost all of the avaiable experimental data. Comparisons between the assessed and experimental data are presented. It is shown that further studies are needed for equilibrium solubilities of AlO_1.5 in ZrO₂ phases. Project supported by the National Natural Science Foundation of China and the National Key Laboratory of Powder Metallurgy Synopsis of the first author Wang Tao, born in 1972, doctoral student, majoring in phase diagram and materials design.     

Effect of particle size on phase structure of ZrO2 produced by hydrolysis of ZrOCl2 solution

A method to produce ZrO2 nano-particles is developed and the effect of particle size on the phase structure of ZrO2 is studied. The method is based on the hydrolysis of ZrOCl2 solution in the reverse micelles of a liquid-liquid two-phase system, in which AOT （sodium 2-ethylhexyl sulfosuccinite） and toluene are chosen as the surfactant and organic phase, respectively. The reverse micelles prevent the aggregation of primary particles, the nano-particle size increases as the AOT content decreases. The TEM, XRD and particle-size analysis results show that the occurrence of metastable tetragonal ZrO2 is attributed to the effect of the particle size other than the effect of the crystallite size. The ratio of t-phase to m-phase increases as the particle size decreases, and 28 nm is the critical size for t-phase to m-phase transformation.     

纳米ZrO2的制备及应用研究进展

综述了纳米ZrO2制备和应用的研究进展.     

FHA bioceramic composite materials enhanced by ZrO2

Experiments for investigating the problem to improve the mechanical properties of FHA [Ca₁₀(PO₄)₆F(OH)] biomaterial have been presented in this paper. ZrO₂ micro-particle, as strengthening phase, is added into FHA matrix material to make a composite biomaterial. Various mechanical properties were tested. Distribution behaviour of ZrO₂ particle in sintered material and phase structure changes of material at elevated temperature were investigated by means of X-ray and SEM. Some biologic experiments were also carried out on animals to estimate the biological function of the composite material. Project supported by the National Natural Science Foundation of China Synopsis of the first author Ruan Jianmin, associate professor, born in 1957, specializing in powder metallurgy as well as bioceramic materials     

微乳液法制备ZrO2超细粉及其表征

以可溶性锆盐溶液为水相，环己烷为油相，聚乙二醇辛基苯醚为乳化剂，正戊醇为助乳化剂的微乳液为基础，以氨气作沉淀剂，在微乳液中发生化学反应，产生凝胶状沉淀，凝胶经离心洗涤、焙烧、得到超细单分散ZrO2粒子，此方法结合了微乳液法和凝胶法的优点，用激光光散射仪的形态和大小，X射线衍射仪对样品作物相分析，并研究ZrO2纳米粉对乙醇的敏感性。结果表明，本法所制备的ZrO2超细颗粒粉末尺寸可控制在20nm的范围内，团聚体＜100nm，物相为单斜相，且有分布均匀、敏感性强等特点，是获得优质超细粒子的新方法。     

Influence of ZrO2 on sintering and crystallization of CaO-Al2O3-SiO2 glass-ceramics

ZrO2 was added into CaO-Al2O3-SiO2 glass-ceramics and the effect of ZrO2 on sintering and crystallization of CaO-Al2O3-SiO2 glass ceramics was investigated. The results show that the sintering shrinkage ratio of glass particles decreases with the increase of the content of ZrO2. ZrO2 has an unfavourable effect on sintering shrinkage ratio of glass particles. The sintering shrinkage ratio of glass particles increases with the increase of sintering temperature. The increase of sintering temperature favors the decrease of the liquid phase viscosity of glass particles. ZrO2 has little effect on crystallization of main crystalline phase （β-wollastonite）. However, it promotes the crystallization at relatively low temperature.     

Transformation toughening of Al2O3/ZrO2 laminated ceramics with residual compressive stress

With the help of scanning electronic microscopy and X-ray diffraction, the relationships of microstructure characteristics, phase assemblage, and fracture micrograph of Al2O3/ZrO2 laminated ceramics were studied. Compared with monolithic Al2O3/ZrO2 ceramics, the existence of surface compressive stresses greatly restrained the growth of ZrO2 and Al2O3 grains at high sinter tem- perature, fined the grain size, and increased the content of metastable t-ZrO2, which made the fracture transformation energy quantity 70% higher than that of the monolithic ceramics. The trans-granular and inter-granular fracture features were observed in the surface and center layers, which further verified that transformation toughening is the main mechanism, whereas, micro-crack toughening is helpful for enhancing fracture toughness.     

Review: Ferromagnetism in Undoped ZrO2 Thin Films

未掺杂氧化锆薄膜的铁磁性研究

宁帅,张政军（清华大学材料学院）

创新点说明：1,通过不同的物理气相沉积方法,实现了对未掺杂氧化锆薄膜的物相调控;2,发现了未掺杂氧化锆薄膜室温铁磁性对物相结构的依赖性;3,通过缺陷分析表征,发现四方相氧化锆的室温铁磁性主要由氧空位缺陷调控。

目的：未掺杂氧化锆薄膜的制备、物相和缺陷调控以及室温铁磁性研究。

方法：脉冲电子束沉积、直流反应磁控溅射、电子束蒸镀。

结果：1,通过不同的物理气相沉积方法,实现了未掺杂氧化锆薄膜的物相调控;2,发现了未掺杂氧化锆薄膜室温铁磁性的物相依赖性;3,通过缺陷分析表征,发现四方相氧化锆的室温铁磁性主要由氧空位缺陷调控。

结论： 1,制备了不同物相结构的未掺杂的氧化锆薄膜;2,发现了四方相氧化锆薄膜可以在室温下呈现铁磁性;3,四方相氧化锆薄膜中的室温铁磁性主要由氧空位缺陷引起。

关键词：氧化锆薄膜,物相调控,室温铁磁性,氧空位缺陷

     

Valence electron structure and properties of stabilized ZrO2

To reveal the properties of stabilizers in ZrO₂ on nanoscopic levels, the valence electron structures of four stable ZrO₂ phases and c-ZrO₂ were analyzed on the basis of the empirical electron theory of solids and molecules. The results showed that the hybridization levels of Zr atoms in c-ZrO₂ doped with Ca and Mg dropped from B17 to B13, the hybridization levels of Zr atoms in c-ZrO₂ doped with Y and Ce dropped from B17 to B15, and that the four stabilizing atoms all made the hybridization levels of O atoms drop from level 4 to level 2. The numbers of covalent electrons in the strongest covalent bond in the descending order are c-ZrO₂>Zr_0.82Ce_0.18O₂>Zr_0.82Y_0.18O_1.91>Zr_0.82Mg_0.18O_1.82>Zr_0.82Ca_0.18O_1.82. The bond energies of the strongest covalent bond and the melting points of the solid solutions in the descending order are Zr_0.82Ce_0.18O₂> c-ZrO₂>Zr_0.82Y_0.18O_1.91>Zr_0.82Mg_0.18O_1.82>Zr_0.82Ca_0.18O_1.82. The percentages of the total number of covalent electrons in the descending order are c-ZrO₂>Zr_0.82Y_0.18O_1.91> Zr_0.82Ce_0.18O₂>Zr_0.82Mg_0.18O_1.82> Zr_0.82Ca_0.18O_1.82. From the above analysis, it can be concluded that the stabilizing degrees of the four stabilizers in the descending order are CaO> MgO>Y₂O₃>CeO₂. Supported by the Major Project of the National Natural Science Foundation of China (Grant No. 90505015)     

Structure and mechanical properties of ZrO2-mullite nano-ceramics in SiO2-Al2O3-ZrO2 system

ZrO2-mullite nano-ceramics were fabricated by in-situ controlled crystallizing from SiO2-Al2O3-ZrO2 amorphous bulk. The thermal transformation sequences of the SiO2-Al2O3-ZrO2 amorphous bulk were investigated by X-ray diffraction, infrared spectrum, scanning electron microscope and differential scanning calorimetric. And the mechanical properties of the nano-ceramics were studied. The results show that the bulks are still in amorphous state at 900 ℃ and the t-ZrO2 forms at about 950 ℃ with a faint spinel-like phase which changes into mullite on further heating. ZrO2 and mullite become major phases at 1 100 ℃ and an amount of m-ZrO2 occur at the same time. The sample heated at 950 ℃ for 2 h and then at 1 100 ℃ for 1 h shows very dense and homogenous microstructure with ball-like grains in size of 20-50 nm. With the increase of crystallization temperature up to 1 350 ℃, the grains grow quickly and some grow into lath-shaped grains with major diameter of 5 μm. After two-step treatment the highest micro-hardness, flexural strength and fracture toughness of the samples are 13.72 GPa, 520 MPa and 5.13 MPa·m1/2, respectively.     

改性WO3/ZrO2固体超强酸催化合成乙酰水杨酸

采用共沉淀法制备WO3/ZrO2及Ce、Mn改性WO3/ZrO2固体超强酸,通过XRD、Raman等方法对改性前后催化剂进行表征,并将其分别用于乙酰水杨酸合成反应考察催化性能,结果表明Ce改性WO3/ZrO2固体超强酸催化效果最好.以Ce改性WO3/ZrO2固体超强酸作为催化剂对乙酰水杨酸合成工艺进行优化,考察反应时间、反应温度、反应物配比及催化剂用量对酰化反应的影响.最佳反应条件下乙酰水杨酸收率达94.69％,且催化剂回收容易,重复使用多次仍具有较高活性.     

SO42-/ZrO2-Al2O3固体超强酸催化合成苯甲酸乙酯

采用沉淀-浸渍法制备了SO42-/ZrO2-Al2O3,固体超强酸,研究了SO42-/ZrO2Al2O3固体超强酸催化苯甲酸与乙醇的酯化反应,结果表明最适宜的反应条件为锆铝摩尔比为l2,醇酸摩尔比为5,焙烧温度500～600℃,焙烧、反应各4 h,催化剂的用量为总量的6.64%.此外,还测定了含氯的固体酸的性能,比较了优化后的固体酸与浓硫酸催化性能.     

混凝法去除水中TiO2纳米颗粒

为了探讨混凝法去除水中纳米颗粒的可行性及最佳条件,研究了无机混凝剂（PAC、PFS、PAFC）和有机絮凝剂（CPAM、APAM、NPAM）对TiO₂纳米颗粒的去除效果,并考察了投加量、pH、沉淀时间、水力条件及有机无机复配对TiO₂纳米颗粒去除效率的影响。单独投加PAC、PFS和PAFC时,三者对应的最高去除率分别为92.51%、84.43%、95.66%。单独投加CPAM、APAM、NPAM时三者对应的去除率仅为61.72%、29.06%、55.37%。复配最佳混凝条件为：投加40 mg/LPAC和3 mg/LCPAM,pH值为9,G值143.5/s,沉淀时间15 min,此时,TiO₂纳米颗粒去除率为99.6%。     

CeO2 的加入对(ZrO2)0.86(MgO)0.14陶瓷电导率的影响

对(ZrO     

Preparation of TiO2 photocatalyst loaded with V2O5 for O2 evolution

TiO₂ photocatalysts loaded with V₂O₅ were prepared via a modified hydrolysis process, and characterized by X-ray diffraction, transmission electron microscopy, Raman spectra and diffuse reflectance UV-Vis spectra measurements. The photocatalytic activity of V₂O₅/TiO₂ was investigated by employing splitting of water for O₂ evolution. The results indicate that V₂O₅ loading can pronouncedly improve the photocatalytic activity of TiO₂ with Fe³⁺ as an electron acceptor under UV or visible light irradiation. The optimum mass fraction of the loaded V₂O₅ is 8%, and the largest speed of O₂ evolution for 8%V₂O₅ (mass fraction) loaded TiO₂ catalyst is 118.2 μmol/(L·h) under UV irradiation, and 83.7 μmol/(L·h) under visible light irradiation.     

Pd负载型介孔ZrO2-TiO2复合材料的设计合成及其CO催化氧化性能研究

为了有效去除大气污染物中的CO,使用氧化还原法制备层状锰氧化物MnO_x-L,并用离子交换法制备了负载不同质量分数Fe的Fex/MnO_x-L催化剂.使用扫描电子显微镜（scanning electron microscope,SEM）、X射线衍射（X-ray diffraction,XRD）技术、比表面积测定（brunauer emmett teller,BET）、热重分析（thermogravimetric analysis,TGA）、氢气程序升温还原（hydrogen temperature-programmed reduction,H₂-TPR）、氧气程序升温脱附（oxygen temperature-programmed,O₂-TPD）、X射线光电子能谱（X-ray photoelectron spectroscopy,XPS）等技术表征催化剂形貌、结构及性能.层状锰氧化物MnO_x-L具有典型的八面体层状结构,Fe负载对催化剂结构影响不大,但对其理化性质产生了影响.Fe负载改变了催化剂的还原性及其表面的m（Fe²⁺）/m（Fe³⁺）和m（O_ads）/m（O_latt）比例,提高了样品的催化活性.在所有Fex/MnO_x-L样品中,Fe5/MnO_x-L具有最高的低温还原性、氧移动性,m（Fe²⁺）/m（Fe³⁺）及表面吸附氧最高.催化氧化CO反应中,Fe5/MnO_x-L具有最佳的催化活性（t₅₀=80℃和t₉₀=150℃）,这与Fe和MnO_x-L载体之间的相互作用有关.

     

Preparation of nano-TiO2 by liquid hydrolysis and characterization of its antibacterial activity

The nano-TiO2 particles were prepared by liquid hydrolysis method and characterized using XRD. Its antibacterial activity against two representative bacterial, Escherichia coli and Staphylococcus aureus, was also studied. The experimental results showed that the nano-TiO2 calcinated at 600-700 ℃ contained the obvious anatase phase and exerted excellent antibacterial activity. The feature of antibacterial activity of nanoTiO2 was non-strains specificity and exerted best antibacterial activity at concentration of 0.8 g/L.     

Properties of plasma sprayed NiCrAlY+(ZrO2+Y2O3) coating on refractory steel surface

NiCrAlY+(ZrO₂+Y₂O₃) thermal barrier coating was prepared on the surface of refractory steel 1Cr18Ni9Ti with plasma spraying technique. The phases and microstructure of the thermal barrier coating were determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the bonding between thermal barrier coating and substrate is sound. The surface hardness of 1Cr18Ni9Ti reaches up to 1 000 HV, but that of substrate is only 300 HV. The patterns sprayed with CoNiCrAlY+(ZrO₂+Y₂O₃) ceramic coating have a good heat insulation effect at 800 °C for heat insulation temperature difference reaches 54 °C, which increases the operating temperature and service life of refractory steel. Foundation item: Project (5040202140) supported by Scientific Research Common Program of Beijing Municipal Commission of Education     

H2O2—Br2溴化对甲苯腈制备对腈基苄溴

研究了在过氧化氢的存在下,用液溴和过氧化氢溴化对甲苯腈制备对腈基苄溴的方法,在回流状态下,把86．4液溴慢性滴加到58．5g对甲苯腈和200g环已烷的混合物中,并分次加入质量分数30％过氧化氢68．2g,反应2h,过滤出沉淀物,用质量分数95％乙醇重结晶,得到腈基苄溴80．3g,收率81．6％。     

基于溶胶凝胶法的TiO2溶胶的制备

用N-N二甲基乙酰胺(DMAC)作溶剂,钛酸丁酯作前驱物,冰乙酸为稳定剂,通过溶胶凝胶法制得了二氧化钛(TiO2)溶胶,并且对加水方式、加水量、溶剂量、pH值、温度等影响因素进行了考察.结果表明,当采用分散加水方式,温度在25℃～35℃以下,DMAC与钛酸丁酯的体积比为3.5:1,V(H2O)/V(Ti(OC4H9)4...