二次纳米自组装制备纳米氧化锆体相催化剂

以二次纳米自组装法制备纳米氧化铝和纳米氧化锆粉体,采取混捏挤条法和压片法分别制备纳米氧化锆体相催化剂。采用BET、SEM等技术对催化剂进行了表征,考察了2种制备方法对催化剂结构与性质的影响。     

ZrO2纳米颗粒的添加对ZrO2/HA复合陶瓷物相和力学性能的影响

将液相掺杂CeO2和Fe2O3的钇稳定四方ZrO2纳米粉作为着色剂添加到微米ZrO2/HA体系中,1400℃烧结制备了ZrO2/HA纳米复合陶瓷.利用X射线衍射分析了复合陶瓷的物相组成;三点弯曲法、单边切口梁法及压痕法测试了陶瓷的力学性能;讨论了纳米氧化锆的添加对复合陶瓷力学性能及物相组成的影响,分析纳米氧化锆导致复合陶瓷力学性能改变的原因.根据复合陶瓷断裂前后单斜相氧化锆的含量变化,证实氧化锆纳米粉的添加不仅有利于复合陶瓷中四方相氧化锆的稳定存在,而且可以提高基体相变四方相氧化锆的含量,相变增韧作用加强.力学性能测试结果显示:体系中适量纳米氧化锆的存在可以提高材料的抗弯强度和断裂韧性20%以上,密度和硬度少量增加,但由于没有新物相引入,对弹性模量未造成影响.     

纳米氧化锆的制备及其在催化领域中的应用

介绍了纳米氧化锆的制备方法，综述了近年来国内外使用纳米氧化锆为催化剂、催化剂助剂及催化剂载体的研究进展，分析了纳米氧化锆的发展前景。     

辅助溶胶–凝胶法制备纳米氧化锆粉体

以八水氧氯化锆为锆源,聚环氧乙烷-聚环氧丙烷-聚环氧乙烷三嵌段共聚物(P123)为分散剂,采用P123辅助溶胶-凝胶法制备纳米氧化锆粉体。在制备过程中,P123经碳化生成的纳米碳颗粒起到了将氧化锆颗粒隔离分散的作用,因此在该方法中无需水洗/醇洗过程去除杂质离子即可获得纳米氧化锆粉体。结果表明:当P123与理论合成氧化锆的质量比为80%,煅烧温度为1 100℃时,能够得到分散性好,粒径分布较窄,中位粒径(D50)仅为158 nm的纳米氧化锆粉体。该方法为环保、高效制备纳米粉体提供了一种新的思路。     

纳米氧化锆粉体的制备

归纳、总结了纳米氧化锆粉体制备的14种方法，分别对每种制备方法的优缺点进行了分析，对制备纳米氧化锆粉体的影响因素进行了探讨，提出了制备纳米氧化锆粉体需要进一步研究和解决的理论问题和技术问题。     

纳米氧化锆在催化领域中的应用

综述了近年来国内外将纳米氧化锆作为催化剂、催化剂助剂及催化剂载体的研究进展,展望了纳米氧化锆在催化剂领域的发展方向.     

纳米颗粒粒径对等离子喷涂法制备氧化锆纳米涂层的影响

利用扫描电镜(SEM)、场发射扫描电镜(FESEM)、透射电镜(TEM)、比表面积吸附法(BET)等分析测试技术,研究了3种不同纳米尺寸氧化锫粉粒的造粒性能、沉积效率以及对等离子喷涂涂层晶粒大小、涂层熔融性能、结合强度的影响.结果表明:纳米氧化锆粉体一次颗粒粒径大小显著影响纳米粉体的喷雾造粒性能、沉积效率、涂层表面粗糙度、涂层晶粒粒径和结合强度大小.本试验中,利用颗粒一次粒径范围为50～70 nm的纳米氧化锆粉体,等离子喷涂制备了晶粒粒径范围为80～120 nm,沉积效率为43%,涂层表面粗糙度为5.92 μm,结合强度为27 MPa的纳米结构氧化锆涂层.     

氯氧化锆前驱体制备纳米氧化锆的机理探讨

介绍了以无机盐氯氧化锆为前驱体，以氢氧化铵为水解促进剂，通过溶胶-凝胶法制备纳米二氧化锆的工艺条件。结合XRD和TG—DSC等测试手段，研究了溶胶-凝胶法制备纳米二氧化锆的机理。结果表明，锆原子在胶体中是以氢氧化锆四聚物的形式存在的，纳米氧化锆是四聚物脱去质子进一步缩聚的结果。     

聚乙二醇分子量对氧化锆粉体粒径的影响研究

为了控制纳米氧化锆粉体的粒径并降低制备成本,以不同分子量(MW)的聚乙二醇(PEG)作为分散剂,采用辅助溶胶-凝胶法制备纳米氧化锆粉体。利用傅里叶变换红外光谱对凝胶体进行了表征,采用激光粒度仪、X射线衍射仪和扫描电镜对纳米氧化锆粉体进行表征。实验结果证明,不同分子量的PEG具有不同的碳转化率,分解所得的碳颗粒所形成的碳隔离作用有助于控制粉体的团聚,纳米氧化锆的粒径与分散剂的碳转化率成反比。     

牙用纳米ZrO_2-白榴石复合烤瓷的制备及性能研究

以钾长石、碳酸钾和纳米氧化锆为主要原料,通过高温固相法,一次性合成了一种牙用白榴石-氧化锆复合烤瓷粉.利用X射线衍射仪和扫描电镜分析烤瓷材料的物相结构,利用万能试验机和热膨胀仪分别测试样品的弯曲强度和热膨胀系数.结果表明:纳米氧化锆的加入,既有利于烤瓷材料的弯曲强度的提高,又有助于调节烤瓷材料的热膨胀系数.当氧化锆的添加量为8%(质量分数),合成烤瓷粉的煅烧温度为1 200 ℃,熔附温度为900 ℃时,样品的弯曲强度为112MPa,热膨胀系数为14.4×10-6/K.     

超细二氧化锆干燥方式探讨

介绍了几种常用的制备纳米粉体的干燥方法。研究了水热反应制备二氧化锆粉体过程中，直接干燥法、共沸蒸镏和超临界干燥3种常用的干燥方法对最终产品粒子大小和微观形态的影响。通过比较，直接干燥法制备的纳米粒子粒径大于100nm，而采用共沸蒸馏和超临界干燥制得的粉体分散性好，可制备出粒径小于10nm的粉体。因此，共沸蒸馏和超临界干燥法是良好的干燥方法。     

Preparation of Zirconia Base Solid Solution Nanopowder by Exothermal Solid-State Synthesis

A new method is put forward to prepare nanometer zirconia base solid solution by exothermal solid-state synthesis. This method is realized by agitating solid mixture of sodium hydroxide, zirconium oxychloride, and yttrium/calcium nitride. Fresh and final powders are studied by X-ray fluorescence, X-ray photoemission spectroscopy, X-ray diffraction, and transmission electron microscopy. The results show the obtained tetragonal/cubic zirconia solid solution nanopowders are highly pure and distribute around 5 nm. It is suggested that the coordinated water of zirconium oxychloride acts as micro medium and the nuclei of solid solution are formed under the superalkaline environment and grow during heat treatment. This method may be useful to prepare other metal oxide nanopowders.     

Microstructure of Mica-Based Nanocomposite Glass-Ceramics

A high-strength machinable glass-ceramic was prepared by controlling the crystallization of ZrO₂-containing Ca_0.43K_0.14Mg₃ (Si₃AlO₁₀)F₂ glass. A unique microstructure of the glass-ceramic was observed, using transmission electron microscopy (TEM): zirconia particles of nanometer size, 20–50 nm, were embedded in calcium mica crystal. After zirconia particles grew in nanometer size, the mica crystals were precipitated to embed the particles. The particles were identified as transformable tetragonal zirconia crystals. This texture leads to high strength (500 MPa in bending) and good machinability.     

SO42-/ZrO2轻质烷烃异构化催化剂的制备和工业应用进展

硫酸化氧化锆固体酸（SO₄^2-/ZrO₂）烷烃异构化催化剂兼具高活性、可再生和环境友好的优点,具有广阔的应用前景。本文综述了SO₄^2-/ZrO₂催化剂在轻质烷烃异构化中的工业应用进展,包括市场现状、现有技术、经济性等方面,并对专利和文献中报道的催化剂制备技术进行了论述总结。重点针对催化剂的关键制备参数以及对催化剂结构和异构化性能的影响进行了深入分析和探讨,包括氢氧化物前体的沉淀和焙烧条件、助剂的添加和改性作用、催化剂预处理条件和原料水含量的影响等。最后对催化剂开发和工业化中的难点给出了分析和建议,并展望了未来的催化剂发展方向,指出拓宽催化剂的原料适应性、发展新型制备技术和助剂体系、结合催化剂再生等工艺研究是未来的发展方向。     

Atomistic investigation of pseudoelasticity in zirconia nanopillars

Molecular dynamics simulations are performed to investigate the underlying atomistic mechanism of the pseudoelastic behavior of zirconia nanopillar. For the [0 0 1]-oriented zirconia nanopillar subjected to uniaxial compressive loading, the strain up to 13.1% can be recovered through inverse martensitic transformation, while larger strain leads to the loss of pseudoelasticity. The irreversible deformation arises owing to the crack propagation, which results from the shear deformation along the phase interfaces. The energy and stress analysis reveals that the responsible mechanism for the pseudoelasticity is the high surface-stress-induced internal stresses at the nanometer scale. The size effect on the martensitic transformation and pseudoelasticity is also elucidated. The simulation results facilitate our understanding of the pseudoelasticity in zirconia nanopillar at the atomic scale.     

Sintering Behavior of Nanocrystalline Zirconia Doped with Alumina Prepared by Chemical Vapor Synthesis

Powders of nanocrystalline zirconia doped with 3–30 mol% alumina have been synthesized using chemical vapor synthesis (CVS). Dense or mesoporous ceramics of small and narrowly distributed grain and pore sizes in the nanometer range are obtained via pressureless vacuum sintering. The microstructural development of the doped samples is strongly dependent on the alumina content. Sintering of zirconia samples with 3 and 5 mol% alumina at temperatures of 1000°C for 1 h results in fully dense, transparent ceramics with grain sizes of 40–45 nm and homogeneous microstructures.     

纳米级氧化锌的研究进展

纳米氧化锌具有许多优异的性能 ,用途广阔。本文综述了纳米氧化锌的研究现状、制备方法、表征方法 ,并提出了研究方向     

Addition of carbon nanotubes during the preparation of zirconia nanoparticles: influence on structure and phase composition

Zirconia powder with an average particle size of 10 nm was prepared by adding carbon nanotubes (CNTs) in the hydrolytic process of ZrO(NO₃)₂. The formation of zirconia nanoparticles was attributed to the addition of CNTs, which affected the zirconia precursor structure. The relation between the stability of cubic (c) and tetragonal (t) phase zirconia at room temperature, and the zirconia particle size and addition of carbon was studied. It was revealed that zirconia particles with nanometer size had took the form of t-phase and that the addition of carbon tended to favor m-phase ZrO₂ to c-phase ZrO₂ transformation and c-phase ZrO₂ stabilization at low temperature.     

Fabrication of High-Strength Continuous Zirconia Fibers and Their Formation Mechanism Study

Continuous zirconia fibers with a nanometer ceramic structure and a tensile strength up to 2.8 GPa were fabricated by pyrolyzing polyacetylacetonatozirconium precursor fibers through a special atmosphere heat treatment. DSC-TGA, GC-MS, IR, SEM, and TEM were used to study the fiber transformation mechanism during heating. Results showed that special atmosphere heat treatment could make the organics in the fibers come out directly without carbonization and remove them almost entirely under 400°C, and the obtained zirconia fibers had few defects, good continuity, and high strength.     

UV固化材料进展

由于UV固化技术固有的特点使其在近几年各个领域都获得了高速的发展,但所占市场份额仍然很小。经过学术界和各大公司的努力,目前已经在UV固化材料方面取得了可喜的成绩。稀释单体、预聚体在数量和质量上都有大幅度增加,发展方向是降低刺激性、低毒和赋予特殊功能:在双光子引发自由基聚合、阳离子光固化、杂混光固化、光产碱催化聚合、无光引发剂光固化、水基固化方面取得了一定的进展;UV粉末涂料克服了传统粉末涂料的缺点脱颖而出,成为近年来研究开发的热点;UV固化纳米材料更是集纳米技术、纳米材料、UV固化技术于一体,预计将会开发出具有特殊功能的新材料;UV固化技术在电子、信息领域也具有很好的发展前景。