溶胶凝胶快速热解法制备ZrO_2超细粉体

采用溶胶凝胶快速热解法制备了ZrO2 超细粉体 ,详细考察了各种制备参数对胶凝时间以及样品性质的影响规律。结果表明 :胶凝时间受溶液中脲含量及胶凝温度影响显著 ;而热解温度、胶溶剂用量、胶凝温度和溶液组成对样品的性状、比表面积、孔分布及粒径均有不同程度的影响     

溶胶共沉淀法制备氧化锆氧化铝复合粉体

用溶胶共沉淀法辅以共沸蒸馏法工艺制备ZrO2/Al2O3复合粉体,研究了pH值和锆与铝的离子比对复合粉体和用这种复合粉体制备的瓷体的力学性能的影响.结果表明:随着溶胶体系pH值的增大,粉体粒径也相应增大.在制备粉体的混合溶液的pH值为8.6左右时,粉体没有明显的团聚且粒径分布均匀.随着氧化铝相对含量的提高,高弹性模量的Al2O3在烧结过程中起钉扎作用,阻碍Zr4 (Y3 )扩散传质的进行和晶界的移动,从而抑制了ZrO2晶体的生长,细化了ZrO2晶粒,表现为氧化锆的结晶温度、烧结体密度和复合陶瓷强度的提高.     

制备条件对ZrO_2超细粒子尺寸及分布的影响

本文采用胶体－超临界流体干燥法制备纳米级ＺｒＯ２超细粉料，用透射电镜（ＴＥＭ）、比表面积（ＢＥＴ）和粒度分析法对颗粒尺寸进行观察和测定，并详细考察了制备条件对产品粒子粒度及其分布的影响     

Enhancing soft magnetic properties of FeSiBNbCu nanocrystalline powder cores by coating ZrO2 insulation layer

The insulation coating plays a crucial role in minimizing core loss (P_cv) in soft magnetic powder cores (SMPCs). In this work, we prepared ZrO₂ coating layer on FeSiBNbCu spherical powder by the hydrolysis-precipitation method and investigated the magnetic properties of the FeSiBNbCu@ZrO₂ nanocrystalline SMPCs. ZrO₂ coating layer were successfully fabricated on the powder by adding a proper amount of K₂ZrF₆ in alkaline ethyl alcohol solution. The micromorphology and chemical structure of the ZrO₂ coating layer on the surface of FeSiBNbCu nanocrystalline powder, as well as the conversion mechanisms, has been investigated. The presence of the ZrO₂ coating reduces the P_cv by significantly lowers eddy loss (P_e) of the nanocrystalline SMPCs, meanwhile improves DC bias performance and slightly decreases their permeability. When the additive amount of K₂ZrF₆ is 1.0 wt%, the nanocrystalline SMPCs has best comprehensive soft magnetic properties, including stable effective permeability (μ_e) of 57.8 up to 1 MHz, excellent DC bias performance of 59.3 % at a bias field of 100 Oe, and the lowest P_cv of 194.7 mW/cm³ at a frequency (f) of 150 kHz and maximum magnetic induction (B_m) of 50 mT.     

Ultrafine particles of the ZrO2-SiO2 system prepared by the spray-ICP technique

Ultrafine powders of the ZrO₂-SiO₂ system prepared by spraying aqueous mixed solutions of ZrO(NO₃)₂·2H₂O and silicone oil into an ultrahigh temperature inductively coupled plasma (the spray-ICP technique) have been investigated in connection with particle growth and phase change caused by heat treatment. The prepared powders were composed of roundish ultrafine particles 10 to 20 nm in size, and their components were tetragonal ZrO₂ (t-ZrO₂) and amorphous SiO₂ (a-SiO₂).a-SiO₂ alone did not crystallize below 1400° C, though the particles grew above 900° C.t-ZrO₂ converted to monoclinic ZrO₂ (m-ZrO₂) above 400° C, also followed by particle growth. On the other hand composite powders oft-ZrO₂ anda-SiO₂ exhibited no particle growth below 1200° C. Above 1200° Ct-ZrO₂ converted tom-ZrO₂, and its amount decreased with an increase in SiO₂ content. At 1400° C particle growth occurred, and the round particles of ZrO₂ were dispersed in ana-SiO₂ glass medium. These results indicate that ZrO₂ and SiO₂ mutually block particle growth, and that SiO₂ contributes to the quenching oft-ZrO₂ by keeping the particles of ZrO₂ within the critical particle size oft-ZrO₂.     

MnOx/ZrO2纳米催化剂的制备及对CO-SCR-NO性能研究

以氧氯化锆和硝酸锰为主要原料，采用Sol—Gel—VFD技术制备了MnOx／ZrO2超细粉体材料。用XRD，TG—DSC，TEM和BET等技术对试样进行了表征，用微反应器-气相色谱仪在线研究了试样不同配合比例对试样催化还原NO的活性的影响。结果表明：用Sol—Gel—VFD技术可制得粒子尺寸约为20nm、具有高催化活性的负载型MnOx／ZrO2纳米催化剂，锰由低价向高价转变。添加了Ce组分能提高MnOx／ZrO2纳米催化剂催化还原NO的活性。     

Preparation and photoluminescence properties of three-dimensionally ordered macroporous ZrO2:Eu3+

Three-dimensionally ordered macroporous (3DOM) ZrO2:Eu3+ (0.5%, 1%, 2% and 5%) were successfully prepared using a polystyrene (PS) colloidal crystal template in combination with a sol-gel method. The structure, morphology, porosity, and optical properties of the materials were well characterized by X-ray diffraction (XRD), Field emission scanning electron micrograph (FESEM), N2 adsorption, and photoluminescence (PL) spectra. The results indicated that the closely packed material exhibited three-dimensional ordering of pores and a strong red (5)D0-->(7)F2 transitions under charge transfer excitation. Strong PL and abundant porosity are of particular interest and give this multifunctional material future potential.     

Mechanochemical synthesis of ultrafine ZrO2 powder

The synthesis of ultrafine zirconia powders by mechanochemical reaction of ZrCl₄ with CaO has been investigated using x-ray diffraction, TEM and DSC measurements. Mechanical milling resulted in a nanoscale mixture of CaO and amorphous ZrCl₄. with no evidence of any reaction having occurred. Subsequent heat treatment at temperatures above 300 °C resulted in the formation of separated particles of cubic ZrO₂,5–10 nm in diameter, within an CaCl₂ matrix. Measurements of the effect of particle size on the crystal structure of ZrO₂ are also reported.     

Laser processing of ZrO2 coatings

Potential materials for protective heat-resistant coatings are the so-called fragmentary porous ceramic layers penetrated by a net of microcracks. The fragments can be shifted easily during thermal cycling procedure, and the micro-cracks prevent the throughout crack propagation, which could destroy the coating. Laser surface processing of coatings is one of the effective ways to form the fragmentary layered structure.

The peculiarities of laser processing of ZrO₂+Y₂O₃ plasma sprayed coatings deposited onto the steel substrate with the Ni-Cr-Al-Y sub-layer alloy were investigated. The coatings were processed by CW CO₂ and Nd:YAG lasers (Fig. 1). The laser processing resulted in melting of the coating surface. The modified coating consisted of a number of macro fragments with sizes 200-500 μm and in turn they consisted of a number of micro-fragments with sizes 20-70 μm. Both types of the fragments are separated by wide (10-15 μm) or narrow (1-5 μm) cracks accordingly. The structure and some properties of the modified coatings such as heat-resistance, hardness, surface roughness, and tightness are investigated depending on the laser output parameters.     

Deposition of Laser Mirrors by Laser Beam Evaporation

A 200W c.w. CO₂ laser has been used to evaporate thin multilayer films of HfO₂-SiO₂ and ZrO₂-SiO₂. Higher values of laser damage resistance were found compared to similar layers produced by electron-beam evaporation.     

ZrO2/Al2O3多孔陶瓷的制备与力学性能

采用凝胶-发泡法制备了ZrO2/Al2O3多孔陶瓷,研究了陶瓷浆料的流变性,固相含量对多孔陶瓷坯体显微结构与力学性能的影响,以及烧结助剂MgO含量与多孔陶瓷抗压强度及气孔率之间的关系.结果表明,在分散剂含量为0.4％(质量分数),球磨4 h,pH值为4的条件下,陶瓷浆料的黏度较低,有利于凝胶注模.固相含量增加,坯体气孔率下降.过高的固相含量使浆料流动困难,注模时引入空气导致坯体内形成较大的气孔甚至裂纹,使坯体抗压强度下降.由ZrO2引起的相变增韧及微裂纹增韧可有效改善多孔陶瓷的力学性能.随烧结助剂含量增加,多孔陶瓷气孔支撑体致密化程度增大,气孔率降低,抗压强度明显升高.多孔陶瓷的抗压强度最高达30 MPa.引入适量的ZrO2及烧结助剂,可制备气孔率适中、抗压强度高的多孔陶瓷.     

溶胶－凝胶工艺合成ZrO_2超微粉末的研究

以自制Ｚｒ（ＯＣ_３Ｈ_７）_４和Ｙ（ＣＨ_３ＣＯＯ）_３为原料，应用溶胶、凝胶法制备了组份为ＺｒＯ_２－９ｍｏｌ％Ｙ_２Ｏ_３超微粉末．实验表明：温度、湿度、溶液的浓度．介质和催化剂等是影响形成溶胶、凝胶的主要因素．通过ＴＧ－ＤＴＡ、ＸＲＤ、ＢＥＴ比表面积测量以及ＴＥＭ等分析手段研究了粉末的结构与性能．结果表明：钇稳定立方相二氧化锆（ＹＳＺ）超微粉末的合成温度在４７０℃左右．粉末经５００℃以上热处理后变为纯立方相结构．５００℃煅烧２ｈ后的超微粉末颗粒呈球形或近似球形，比表面积为６４．０４ｍ￣２／ｇ，粒径为１５．７ｎｍ．随着烧结温度的升高，ＹＳＺ超微粉末的比表面积减小，粒径增大，预示着颗粒间发生团聚，一次颗粒间的团聚引起了表面积的明显损失和界面的形成．     

Preparation and properties of cubic ZrO2 stabilized with Ni(II)

Samples of cubic stabilized ZrO₂ have been prepared by the code-composition of nickel nitrate and zirconyl nitrate at 500°C. A comparison of the stability towards reduction of the bulk NiO and the Ni(II) in the cubic stabilized ZrO₂ deomstrates the influence of the stabilization of cubic ZrO₂ with Ni(II).     

硬脂酸法制备纳米ZrO2

以氧氯化锆为原料，采用硬脂酸溶胶工艺制备出了纯氧化锆及钇稳定的氧化锆（YSZ）纳米晶。用傅立叶变换红外光谱（FT－IR）和热重（TG）、差热（DTA）分析仪对反应历程进行了分析，X射线衍射仪（XRD）进行物相分析及粒径计算，透射电镜（TEM）观察粒子形貌。结果表明，该工艺方法简单且制备的纳米晶颗粒均匀，分散性较好。     

溶胶-凝胶法制备ZrO2缓冲膜的研究

本文用溶胶-凝胶技术,以无机盐氧氯化锆（ZrOCl2·8H2O）为前驱体,在不锈钢表面上制备了含SiO2相的ZrO2缓冲膜,并用真空蒸镀法在其上沉积一层厚度为150nm的金膜．通过XRD、FTIR、SEM及AES等测试手段对ZrO2缓冲膜的性能及其热处理过程中的物理化学变化进行了表征.结果表明;不锈钢箔基体上的四方ZrO2膜在（200）晶面上有择优取向的特点,缓冲膜与基体之间存在着一定程度的互扩散作用．同时,法向热发射率的测试结果表明,850℃热处理后材料仍能保持极低的热发射率（ε=0．043）,说明缓冲膜有效地阻挡了金膜与基体之间的高温互扩散作用．     

Fabrication and microstructure of ZrO2-Ni functional gradient material by powder metallurgy

Functional gradient material (FGM) of the ZrO₂-Ni system was developed by a powder metallurgical process, and investigated for its microstructure by means of X-ray diffractometry (XRD), electron probe microanalysis (EPMA), transmission electron microscopy (TEM) and optical microscopy. It was shown that the sintered body of ZrO₂-Ni FGM is almost fully densified, and its chemical composition and microstructure have the expected gradient distribution. With composition variation, the microstructure changes gradually from zirconia particles dispersed in a nickel matrix to the converse with nickel particles dispersed in a zirconia matrix, with network structures in the intermediate composition range. Therefore, no distinct interfaces appear in the FGM due to the gradient change of components, that is, both zirconia and nickel are present everywhere in the microstructure. In phase composition, the sintered ZrO₂-Ni FGM consists of nickel, tetragonal zirconia and a little monoclinic zirconia. No reaction between nickel and zirconia has been detected. The substructure of nickel and monoclinic zirconia are twins, and strain fringes can also be found in zirconia.     

Preparation and properties of Y2O3-doped ZrO2 thin films by the sol–gel process

Y₂O₃-doped ZrO₂ (YZ) thin films were prepared on alumina substrates by the dip-coating process. The dip-coating solution consisted of a homogeneous sol, and was prepared by using the respective chlorides as raw materials, with ethylene glycol, 2-butanol and distilled water as solvents. The thin films containing 0–20 mol % Y₂O₃ were successfully produced by thermal treatment above 600 °C. The characterization for the film preparation was performed by means of thermogravimetric–differential thermal analysis for the thermal analysis, and scanning electron microscopy for the morphological analysis and thickness measurements. The properties of the films were characterized in terms of a study of the crystalline phase, the crystallite size, the microstructure and the electrical conductivity by using X-ray diffraction, scanning electron microscopy and the complex impedance techniques. In all YZ thin films, the tetragonal phase was stable at low temperatures as a result of the crystallite size effect. However, at higher temperatures, the tetragonal phase was transformed into either the monoclinic phase or the cubic phase, depending on the doping concentration. The YZ thin film of 8 mol% Y₂O₃ content was stabilized to almost cubic phase at 1000 °C. Resonable conductivity behaviour at YZ was observed for the YZ thin films. The electrical conductivity of YZ thin films was similar to the values of the sintered body. This revised version was published online in November 2006 with corrections to the Cover Date.