掺杂TiO2对硅气凝胶高温绝热性能的影响

以TiO2作为红外遮光剂,采用溶胶凝胶工艺,研究了遮光剂添加量、超声功率和时间、pH值等对硅气凝胶性能的影响,从而制备出具有高温绝热性能的硅气凝胶。利用扫描电子显微镜(SEM),BJH比表面积及孔结构测定,红外线光谱分析仪(FT-IR)等手段对所得样品进行表征。结果表明:当TiO2掺量为5%时,表观密度为0.122g/cm3,比表面积497.23m2/g,平均孔径24.8nm,孔隙率高达95%。     

利用粉煤灰常压干燥合成SiO2气凝胶的研究

为了实现粉煤灰回收利用的新途径,研究了一种利用粉煤灰为硅源常压干燥合成SiO2气凝胶的工艺.通过正交实验研究粉煤灰与氢氧化钠反应生成水玻璃的最佳工艺条件;所得水玻璃溶液通过硫酸催化或树脂交换碱催化法获得水凝胶,利用三甲基氯硅烷/乙醇/正己烷对水凝胶进行改性处理,在常压干燥下制备了SiO2气凝胶.利用BET、SEM和FTIR对气凝胶的微观结构及性质进行了研究,结果表明,所得气凝胶的比表面积为362.2～907.9m2/g、孔体积为0.738～4.875cm3/g、平均孔径为7.69～24.09nm,其中树脂交换碱催化法所得气凝胶的比表面积可达907.9m2/g,孔体积达4.875cm3/g.     

改性剂对二氧化硅气凝胶性能的影响

本文以正硅酸乙酯(TEOS)为前驱体,通过酸碱两步溶胶-凝胶法,常压干燥制备疏水性SiO2气凝胶。研究了两种改性剂(三甲基氯硅烷、六甲基二硅氮烷)对二氧化硅气凝胶结构和性能的影响。对制备的气凝胶样品进行表面微观形态分析、热重差热分析、傅里叶红外分析以及比表面积分析。结果表明,通过改性制备的样品具有较好的性能,使用六甲基二硅氮烷改性得到的SiO2气凝胶密度为0.204g/cm3,接触角为128°,BET比表面积为973m2/g,平均孔径7.57nm;使用三甲基氯硅烷改性得到的SiO2气凝胶密度为0.115g/cm3,疏水性优良,接触角为158°,BET比表面积为1067m2/g,平均孔径13.40nm。综合考虑各种因素,采用TMCS进行改性制备得到的SiO2气凝胶综合性能更加优异。     

水玻璃法SiO_2气凝胶的制备及其疏水改性

以水玻璃为硅源,水为溶剂,采用冷冻干燥法制备了纳米多孔SiO_2气凝胶材料。采用三甲基氯硅烷(TMCS)和六甲基二硅胺烷(HMDS)进行疏水改性,以减少样品在使用过程中的收缩和坍塌。结果表明,TMCS疏水改性SiO2气凝胶的表观密度为0.1682g/cm3,比表面积为363m2/g,HMDS疏水改性SiO_2气凝胶的表观密度为0.2536g/cm3,比表面积为336m2/g。SEM测试结果表明,所得产品具有非晶纳米介孔结构。接触角测定分析表明,TMCS疏水改性SiO2气凝胶与水的接触角为149°,表现出良好的疏水性。     

间苯二酚-糠醛气凝胶的制备与表征

以氢氧化钠为催化剂和乙醇为溶剂合成间苯二酚-糠醛凝胶,经乙醇超临界干燥后得到有机气凝胶.间苯二酚与催化剂的摩尔比、间苯二酚与糠醛的摩尔比以及反应物总浓度等制备条件是影响有机气凝胶密度的主要因素.TEM和N2吸附法表明,有机气凝胶具有典型的三维纳米网络结构,网络颗粒约为10nm,平均孔径为7.8nm,其BET表面积和中孔体积分别为589 m2/g和1.106 cm3/g.     

分子筛吸附性能分析

对一种沸石分子筛样品的比表面积、孔体积以及孔分布进行了测试分析.该样品的吸附等温线呈现I型,比表面积为756.3m2/g.由αs法和t-图法得到该样品的微孔体积非常接近,约0.22 mL/g.由DFT法得到该样品的孔径为0.6 nm.     

石墨纤维的比表面积与孔隙结构的测定与分析

为了定量地描述和分析石墨纤维的比表面积和孔隙结构,采用低温氮吸附法测定石墨纤维在液氮温度和不同压力条件下的氮气吸附-脱附等温曲线.研究表明石墨纤维属于微孔材料,含有大量的微孔和极少量的介孔;石墨纤维的BET比表面积、总孔体积和平均孔径分别为541.00m2/g、0.2436cm3/g、1.8010nm,其微孔的比表面积...     

SiO2-TiO2复合气凝胶制备研究

采用同步溶胶凝胶方法,制备了TiO2分布均匀的SiO2-TiO2复合气凝胶.研究了SiO2溶胶预反应时间、不同催化剂和螯合剂对复合溶胶凝胶过程的影响,并用BET、SEM和XRD等测试方法对其结构进行了表征;复合SiO2-TiO2气凝胶具有典型的气凝胶特征,其比表面积为483.35m2/g,密度在0.1～0.12g/cm3范围内.     

常压干燥法制备TiO2气凝胶

以钛酸丁酯为原料, 以甲酰胺为干燥控制化学添加剂控制凝胶网络结构, 采用溶胶－凝胶法制得TiO₂醇凝胶; 结合正硅酸乙酯母液浸泡和低表面张力溶剂替换及常压干燥等后处理步骤, 实现了TiO₂气凝胶的常压干燥法制备. 采用XRD、BET、TEM、SEM、EDS及FT-IR等测试手段对样品进行表征. 结果表明：所制备的TiO₂气凝胶为无定形结构, 表观密度为0.375g/cm³, 比表面积达523m²/g, 平均孔径约9.9nm; 经850℃空气气氛下煅烧4h后, TiO₂气凝胶转变为锐钛矿型结构, 平均孔径增大到16.3nm, 比表面积仍达208m²/g. 本研究提出的制备方法简单, 所制备的气凝胶比表面积高、热稳定好.     

掺杂六钛酸钾晶须SiO_2气凝胶复合材料的研究

以正硅酸四乙酯(TEOS)为硅源,在溶胶-凝胶过程中添加六钛酸钾晶须制备SiO2复合凝胶,通过表面改性和超临界CO2干燥技术获得了大块无裂纹的SiO2气凝胶复合材料。由分析可知,SiO2溶胶的凝胶时间与溶胶体系酸碱性有密切关系,而掺杂不同含量的六钛酸钾晶须对凝胶时间无显著影响;用红外光谱(FT-IR)、BET技术等进一步对其表征,结果表明,制备的样品密度范围为0.20g/cm3~0.29g/cm3,经过疏水改性后,气凝胶表面存在大量憎水基团。BET检测显示,SiO2气凝胶复合材料比表面积达到700m2/g以上,平均孔径为18nm左右,是一种轻质纳米多孔材料。     

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.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

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.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

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.     

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