溶胶-凝胶法制备纳米TiO2

用溶胶 -凝胶法制备纳米TiO2 粉晶。用X射线粉末衍射 (XRD)对不同温度热处理的系列粉末进行了研究 ,结果表明用溶胶 -凝胶法制备的TiO2 纳米晶其晶型转变温度与凝胶时间有关     

溶剂对溶胶-凝胶燃烧法合成YAG粉体的影响

以Y(NO3)3.6H2O、Al(NO3)3.9H2O和柠檬酸为原料,分别以去离子水和无水乙醇为溶剂,采用溶胶-凝胶燃烧法合成YAG粉体。借助FT-IR、XRD、SEM等分析仪器研究了溶胶-凝胶燃烧法合成YAG粉体的过程,重点讨论了前躯体溶液不同溶剂对溶胶-凝胶燃烧法合成过程及合成产物的影响。结果表明:去离子水和无水乙醇对合成的YAG粉体的形貌和分散性有重要的影响。     

Cu/SiO2纳米复合气凝胶的制备与表征

采用含铜硅酸乙酯(CuTEOS)进行溶胶-凝胶反应来制备高Cu含量的Cu/SiO2纳米复合气凝胶,复合气凝胶中的Cu含量可在小于66%(质量分数)的范围内调节.研究了水量、催化剂浓度、溶剂量及含铜硅酸乙酯的组成对溶胶-凝胶过程的影响.本研究中Cu/SiO2纳米复合气凝胶中粒子粒径大部分小于25nm,其孔径小于50nm,比表面积在400～650m2/g范围内.     

由多聚硅氧烷制备二氧化硅气凝胶

SiO2 气凝胶是一种新型轻质纳米多孔材料。本工作以多聚硅氧烷 (E -4 0 )为硅源 ,用溶胶 -凝胶法制备出了SiO2气凝胶。研究了催化剂、温度、水等因素对其溶胶 -凝胶过程的影响 ;讨论了F离子以及水对E -4 0水解 -缩聚反应的作用机理 ;并用孔径分布测定仪、TEM等方法对其微结构进行了研究。结果表明 :由E -4 0为硅源制备的SiO2 气凝胶骨架颗粒为十几nm ;孔径分布较广 ,其峰值在 3 0nm附近 ,此外 ,还存在几nm的微孔。     

溶胶-凝胶法制备三元金属氮化物薄膜及其最新研究进展

三元金属氮化物薄膜是一类在电子、铁磁等领域具有广阔应用前景的新材料,主要有立方金属(反)钙钛矿和立方η碳化物(η-carbide)两种结构类型,由于其卓越的性能如高硬度、超导性、催化性以及各种不同的磁学性能而引起人们广泛的研究。本文主要介绍了三元氮化物结构特性以及溶胶-凝胶法(Sol-gel)在这些氮化物制备方面的应用,阐述并分析了溶胶-凝胶法的优缺点;简述了溶胶-凝胶法制备其他三元金属氮化物薄膜(如铁磁薄膜)的应用;最后指出了溶胶-凝胶法目前存在的一些问题。     

二氧化硅气凝胶的制备方法研究

二氧化硅气凝胶的制备主要经历溶胶-凝胶过程以及随后的超临界干燥过程.详细描述了这2个阶段的特点,并对不同干燥方法进行了比较.同时也对影响二氧化硅气凝胶结构和性质的因素进行了分析.     

有机硅溶胶-凝胶防腐蚀涂层研究进展

有机硅溶胶-凝胶涂层是指以烷基烷氧基硅烷为前驱体通过溶胶-凝胶技术制备的涂层。有机硅是分子水平上的有机-无机杂化分子,因此有机硅溶胶-凝胶涂层兼具了有机材料和无机材料的性能,并且能通过合理的调控有机和无机成分来获得所需的性能。其热稳定、耐刮擦性与无机材料的结合性能明显高于普通的有机材料,柔韧性与有机材料的结合性能明显高于一般的无机涂层。近年来,这种新型的、具有特殊性能的涂层被广泛研究用来保护金属材料(如铝、铁、镁、铜基材料)。介绍了有机硅溶胶-凝胶涂层涉及的基本反应、硅烷在金属表面上的成键机理以及在不同金属上的应用等方面的研究进展,并展望了有机硅溶胶-凝胶涂层应用前景及未来的研究方向。     

改性溶胶-凝胶法制备ZrO_2纳米晶粉及其团聚控制

对溶胶 -凝胶法进行改性 ,使凝胶聚沉为沉淀物 ,进而可以成功地合成ZrO2(9%Y2O3)纳米粉体。采用热重 -差热(TG -DTA)分析、粒度分布分析、透射电子显微镜(TEM)和X射线衍射(XRD)测试法对粉料制备工艺过程进行了研究。结果表明 ,改性的溶胶 -凝胶法在聚沉前加入分子量大小不同的表面活性剂 ,聚沉后采用无水乙醇超声分散 ,可以有效地消除团聚现象。沉淀产物在450℃以下可以完全分解为ZrO2(Y2O3)粉体 ,600℃煅烧颗粒晶粒度为14nm。     

二氧化硅凝胶的疏水改性及表征

以正硅酸乙酯为原料,经溶胶-凝胶过程制备二氧化硅溶胶,再利用二甲基二乙氧基硅烷(DDS)对其进行改性,制备疏水性二氧化硅凝胶.用红外光谱、接触角,热重分析及原子力显微镜等测试方法对试样的结构、疏水性、热稳定性及形貌进行分析.结果表明,改性后的样品是表面存在疏水基团—CH3的疏水凝胶;热稳定性较好,600℃之后没有明显的质量损失,热处理温度定于400℃可保证其疏水性;表面均一平整,孔隙率较高.     

溶胶法原位复合聚乙烯醇/羟基磷灰石水凝胶的结构与性能研究

研究了制备聚乙烯醇(PVA)/羟基磷灰石(HA)复合水凝胶的溶胶法原位复合技术,将无机纳米粉体的溶胶-凝胶合成反应引入高分子基体。对该法制备的复合水凝胶的相结构、微观形貌和拉伸强度进行了分析,并与物理共混法复合水凝胶加以比较。结果表明,溶胶法原位复合可以在富水基体中制备晶相的HA粉体,且粉体粒径小于200nm,分散良好,复合材料的力学性能也有进一步改善。     

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.……     

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.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.