(Pb,Ca,La)TiO3纳米晶的制备及其表征

以金属醇盐和无机盐为原料，用溶胶-凝胶法合成了纳米级（Pb，Ca，La）TiO3用不同的退火温度和时间对样品进行处理后得到相应粒径的纳米晶粉．再用差热分析、X－ray衍射分析；对合成过程进行了研究。用TEM考察样品的粒度和形貌，用FT－IR对（Pb，Ca，La）TiO3纳米晶红外透射谱进行了测试分析．     

微波水热合成法制备TiO_2纳米管的晶型和形貌研究

采用溶胶-凝胶法合成TiO2纳米粉,并分别在500、600和700℃进行煅烧。并以此为前驱物,采用微波水热合成法制备TiO2纳米管。用X射线衍射(XRD)、场发射扫描电镜(FESEM)和场发射透射电镜(FETEM)分别对TiO2纳米粉和纳米管进行表征。结果显示,煅烧温度影响TiO2纳米粉晶粒尺寸,微波水热合成法对TiO2纳米管的晶型和结晶度的影响明显。同时研究TiO2纳米管的晶型和结晶度的变化机制,结果表明,以600和700℃煅烧的TiO2纳米粉为前驱物经微波水热合成法合成的TiO2纳米管中部分热力学亚稳态的锐钛矿向稳定态的金红石进行转变。     

纳米二氧化钛粉体晶相控制实验研究

在水解－沉淀法制备纳米TiO2粉体的过程中，使用不同的沉淀剂获得了晶相不同的纳米TiO2粉体，使用混合沉淀剂，通过控制沉淀剂的比例，制备了晶相组成（金红石与锐钛矿比例）不同的纳米TiO2多晶粉体，采用相同的粉体制备工艺，不同的后续处理工艺，探讨了锐钛矿向金红石转变的相变温度，经分析研究后认为，水解－沉淀法制备的纳米粉体中的锐钛矿向金红石红转变的温度为500－800℃，完全转变的温度在800℃以上；纳米TiO2多晶粉体的晶相组成不仅与沉淀剂的种类，混合沉淀剂中沉淀剂的比例和粉体的煅烧温度有关，而且与粉体的后续处理工艺和粉体表面界面相的稳定性有关。     

钛酸锶铅纳米陶瓷粉的制备及其烧结致密化行为

采用化学共沉淀法制备了一系列(Sr1-xPbx)TiO3陶瓷粉体,通过差热-热重(DTA-TG)分析确定了共沉淀产物的煅烧温度.X射线衍射(XRD)分析表明,化学共沉淀产物基本上呈非晶态,随后煅烧过程中发生晶化,主晶相为立方(Sr1-xPbx)TiO3固溶体.随着Pb含量的增加,逐渐出现游离的四方PbTiO3次晶相.所制得的(Sr1-xPbx)TiO3粉体具有纳米晶粒及纳米颗粒结构,平均晶粒及颗粒尺寸分别为20～30 nm和20～50 nm;颗粒形貌为不规则球形,团聚较为严重,以一次团聚颗粒为主,平均直径为200 nm,较大的二次团聚体平均粒径约为750 nm.纳米粉体烧结成瓷的温度显著降低,在1 150℃烧结基本实现致密化,而且由烧结前的立方相为主完全转变为四方相,没有了游离的PbTiO3并存在铁电畴亚结构.     

纳米TiO2粉体的制备及其表征

采用溶胶-凝胶技术制备了纳米TiO2粉体,并对其热性能、相结构、颗粒大小和分布进行了表征,结果表明,TiO2干凝胶粉经300℃煅烧后已有锐钛矿相出现,经550℃煅烧后有金红石相出现,完全相转变的温度约为600℃,纳米TiO2粉体的颗粒尺寸随煅烧温度的升高而增大,采用溶胶,凝胶技术制备的干凝胶粉经400℃煅烧后可获得团聚轻、颗粒大小分布比较均匀、颗粒尺寸约为15nm的球状TiO2粉体,     

晶化处理温度对钛系凝胶光催化降解性能的影响

采用溶胶-凝胶法制备了掺Pb和Si的TiO2纳米粒子,用XRD和UV-VIS检测技术对所制的样品进行了表征.以苯酚的光催化降解为对象,考察了晶化处理温度及掺Pb、Si对材料结构、组成和光催化性能的影响;结果表明,掺入Pb、Si提高了TiO2纳米粒子中锐钛矿和金红石的晶化温度,TiO2纳米粒子的光催化活性得到较大的提高.在900℃进行晶化处理的SiTiPb复合凝胶的光催化活性最优.     

Ag~+/TiO_2-ZnO纳米复合薄膜的制备及双亲性能

采用溶胶-凝胶法制备了TiO2薄膜、TiO2-ZnO纳米薄膜和Ag+/TiO2-ZnO纳米薄膜。通过X射线衍射和原子力显微镜表征了样品的晶相、晶粒尺寸和形貌。以水(H2O)作为极性溶液参照物、苯(C6H6)作为非极性溶液参照物,研究了掺杂量、煅烧温度、表面处理对薄膜光致双亲性的影响。结果表明:在ZnO/TiO2复合薄膜中,适量掺杂Ag+会提高其双亲性,摩尔比为1%时最佳。煅烧温度的不同能够导致薄膜的晶粒粒径、晶型及薄膜表面的粗糙度发生变化,从而影响薄膜的双亲性能。煅烧温度为550℃、经酸溶液或热处理后Ag+/TiO2-ZnO纳米薄膜的双亲性最佳,其晶粒粒径约为21.1nm。此时,亲水角和亲油角分别为2°和0.5°。Ag+/TiO2-ZnO纳米薄膜的双亲性明显高于纯TiO2和TiO2-ZnO纳米薄膜。     

溶胶-凝胶正交试验法制备纳米TiO2薄膜及其光电催化性能评价

以钛酸丁酯用量、涂层数、煅烧温度和时间为影响因素,设计L9(3)4正交试验,用溶胶-凝胶法制备了纳米TiO2薄膜,以暂态电流积分电量作为评价指标,考察了这4个因素对纳米TiO2薄膜的光电催化性能的影响,从而得出了最佳的制备工艺:钛酸丁酯用量10mL、煅烧温度550℃、煅烧时间3h、涂层数2层.并对最佳制备工艺下制得的TiO2薄膜进行微观结构表征.     

纳米TiO_2薄膜电极的制备及其光电化学响应

采用溶胶-凝胶法在氧化铟锡(ITO)导电玻璃上制备了纳米TiO2薄膜电极,研究了不同制备条件下TiO2薄膜的光电化学响应。利用X射线衍射仪对纳米TiO2的晶型结构进行了分析,利用原子力显微镜(AFM)对薄膜的表面形貌进行了表征。结果表明:随煅烧温度升高,锐钛矿(101)晶面的衍射峰强度增强;加入抑制剂且煅烧温度为650℃时制备的纳米TiO2为锐钛矿晶型,薄膜粒度分布均匀、尺度适宜,且表面存在一定孔隙。暂态电流测试表明:在光强为6.6mW/cm2、极化电位为+0.3V时,随着预吸附时间的延长,瞬时产生的峰值电流逐渐增大;当预吸附时间为300s时,随着煅烧温度的升高,TiO2薄膜电极对H2O分子的催化氧化光电流由24.2μA(450℃)提高到49.0μA(650℃)。     

直接氮化法制备纳米晶TiN薄膜

首先采用溶胶-凝胶法在Al2O3基体上制备了TiO2纳米晶薄膜，然后在管式气氛炉中，用氨气作为还原剂，直接氮化制备TiO2纳米晶薄膜；从而成功地的α-Al2O3陶瓷基片上制备了纳米晶TiN薄膜。利用XRD、XPS、FE-SEM等分析技术，研究了制备的纳米晶TiN薄膜的相组成及形貌。结果表明最佳工艺条件为：氮化温度为700℃，氮化时间为1h。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.