改性高岭土/钛氧化物复合材料的制备及其高电流变活性

采用sol-gel法和机械化学法相结合制备了改性高岭土/钛氧化物颗粒,与甲基硅油配制成电流变液。XRD、FTIR分析表明,钛氧化物以含介孔的非晶态形式包覆在经过机械化学法制备的高岭土/NaCl复合物上,形成改性高岭土/钛氧化物复合颗粒。电流变性能测试表明,当颗粒体积分数为25％,E=3 kV/mm时,复合颗粒电流变液的静态屈服应力达7 kPa,是高岭土电流变液的9倍。同时发现钛氧化物含量对电流变效应有重要影响。电流变液介电性能的变化是其流变学性能提高的起源。     

硅油端基对草酸氧钛电流变液性能的影响

以草酸氧钛纳米颗粒为分散相,以粘度相近、端基不同的硅油(羟基硅油、甲基含氢硅油、二甲基硅油)为基液制备电流变液,测试其剪切屈服强度、零场粘度、漏电流密度、剪切稳定性、沉降稳定性,以研究硅油端基结构对电流变液性能的影响。测试结果表明,以极性端基能够提高电流变液的剪切屈服强度、电流变效率及沉降稳定性,但导致漏电流密度增大;空间位阻作用较小的端基能够提高电流变液的剪切屈服强度、电流变效率,降低漏电流密度,但导致沉降稳定性变差。     

硅油端基对草酸氧钛电流变液性能的影响

以草酸氧钛纳米颗粒为分散相,以黏度相近,端基不同的硅油(羟基硅油、甲基含氢硅油、二甲基硅油)为基液制备电流变液,测试其剪切屈服强度、零场黏度、漏电流密度、剪切稳定性、沉降稳定性,以研究硅油端基结构对电流变液性能的影响。测试结果表明,以极性端基能够提高电流变液的剪切屈服强度、电流变效率及沉降稳定性,但导致漏电流密度增大;空间位阻作用较小的端基能够提高电流变液的剪切屈服强度、电流变效率,降低漏电流密度,但导致沉降稳定性变差。     

温度对电流变体智能材料的性能影响

本文通过化学合成的方法制备了含氯离子(Cl-)的草酸氧钛钡(BTO)颗粒材料,以甲基硅油Ⅰ为基础液,制备了电流变体,考察了该体系的粘度和流变等性能随温度的变化规律。     

电喷法钛氧/聚乙烯吡咯烷酮/硬脂酸颗粒及其电流变性能

采用电喷法制备钛氧/聚乙烯吡咯烷酮/硬脂酸(钛氧/PVP/SA)微纳米颗粒。SEM、粒径分析表明钛氧/PVP/SA颗粒为规则球状,平均尺寸为236.7nm;FT-IR表明PVP、SA成功引入钛氧颗粒;XRD表明钛氧/PVP/SA颗粒为无定形态。分别以电喷法钛氧/PVP/SA、水解沉淀法钛氧/PVP/SA颗粒为分散相,制备质量分数为43%的电流变液。电流变性能测试结果表明,电喷法钛氧/PVP/SA电流变液比水解沉淀法钛氧/PVP/SA电流变液具有更高的剪切屈服强度及剪切稳定性。     

聚苯胺修饰草酸氧钛钡电流变性能的研究

采用原位氧化聚合法对草酸氧钛钡(BTO)粒子进行聚苯胺(PAn)修饰.发现聚苯胺的修饰极大地改善了草酸氧钛钡粒子与硅油的漫润性和所配制的电流变液的力学性能.当聚苯胺的修饰量为1.7%时,复合粒子表现出最佳的电流变效应,其静态剪切应力高达54.5kPa,是未修饰草酸氧钛钡粒子电流变液剪切应力的3.3倍.界面极化能力的增强和浸润性的改善是其ER性能显著提高的主要原因.     

包覆型高岭土/二氧化钛纳米复合颗粒的电流变效应

采用溶胶-凝胶法制备了一种新型高岭土/二氧化钛纳米复合电流变液材料.XRD、FT-IR、SEM分析表明TiO₂以纳米晶的形态包覆于高岭土表面.电流变性能测试表明,不同的TiO₂质量比的复合颗粒电流变液效应不同,且都比纯高岭土电流变有显著提高.同时当复合颗粒中TiO₂质量百分比在34％,颗粒硅油体积分数为25％,直流电场为3kV/mm时,高岭土/二氧化钛纳米复合材料电流变液的静屈服应力达3.4kPa,是纯高岭土电流变液的5倍.     

乳状电流变基液及其对材料性能的影响

研究试制了乳状电流变基液，以二甲基硅油为基体，二甲基亚砜作添加剂，在超声波的作用下使二甲基亚砜分散于硅油中形成稳定的乳状液，测试了该乳液的介电常数，电导率及介电损耗。以此乳液作基液，与稀土改性TiO2和BaTiO3等固体颗粒配成电流变液，并对其流变性能进行测试。实验结果表明：用该乳液作基液配制的电流变液化用纯硅油作基液配制的电流变液介电性能有较大的改善，电流变性能显著提高。     

SDBS改性丙三醇氧钛颗粒的电流变性能研究

以十二烷基苯磺酸钠(SDBS)为表面活性剂,通过水热法对丙三醇氧钛(Gly-O-Ti)电流变颗粒进行表面改性。研究了SDBS对Gly-O-Ti电流变液性能的影响并讨论了其作用机理。结果表明在Gly-O-Ti电流变液制备过程中加入适量SDBS,可有效提高体系的电流变力学性能,并降低其漏电流密度。     

改性纳米氧化钛电流变液的制备及其特性

利用水解法与溶液沉积法, 合成了丙烯酰胺、十二烷基苯磺酸钠(SDBS) 改性氧化钛纳米电流变颗粒。经XRD 测定颗粒为无定形态, 用TEM 观察了粒子的形貌, 粒度分析表明颗粒粒径分布为70～300 nm , FTIR 图谱显示氧化钛上修饰有丙烯酰胺、SDBS。SDBS 的加入影响了颗粒的尺寸、表面性质及颗粒与硅油的润湿性, 最终引起电流变液介电性质的改善。丙烯酰胺的加入量也会影响电流变效应。电流变性能测试表明, 当SDBS/ 水质量比为1. 875 % , 丙烯酰胺/ 水质量比为0. 750 %时, 材料呈现最佳的电流变效应, 5 kV/ mm 直流电场下的静态剪切应力可达90 kPa , 电流变液具有极好的抗沉淀稳定性。这种优异的电流变效应源于颗粒界面极化的增强。      

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.