疏水型气相法白炭黑对RTV-1硅橡胶性能影响

对比研究疏水型TS-530和亲水型M-5两种气相法白炭黑对单组分室温硫化(RTV-1)硅橡胶补强和热稳定性的影响及其在体系内的分散性。结果表明,疏水型气相法白炭黑整体补强效果和分散性更好,且填充量为20~25 phr时,补强效果最好;疏水型气相法白炭黑产品的热稳定性优于亲水型产品的热稳定性。     

天甲胶乳对天然橡胶/白炭黑复合材料的增容作用研究

天甲胶乳(MG)是甲基丙烯酸甲酯与天然胶乳的接枝共聚产物,主要用于粘合表面性质不同的材料。在湿法混炼工艺的基础上,以天甲胶乳作为增容剂对天然橡胶/白炭黑复合材料进行增容。研究了MG对复合材料中白炭黑分散性、硫化特性、Payne效应、物理机械性能、动态力学性能的影响。结果表明,采用MG增容天然橡胶/白炭黑复合材料时,白炭黑含量为10 phr时平均粒径最小,分散等级最高,分别为7.6μm和9.9。NR/SiO_2-MG的正硫化时间有所下降,白炭黑为40 phr时T_(90)缩短最明显,从17.2 min降低到13.9 min。在白炭黑含量10 phr时,NR/SiO_2-MG的Payne效应明显降低,白炭黑在NR基体中分散性能提高,胶料加工性能改善。加入增容剂的NR/SiO_2-MG的拉伸强度和撕裂强度都比未添加增容剂样品好。NR/SiO_2-MG的抗湿滑性在白炭黑为20 phr时明显提高,同时NR/SiO_2-MG的滚动阻力明显降低。     

高硬度有机硅橡胶耐热性能与回弹性能的改善

通过添加气相法白炭黑增加硅橡胶硬度,添加金属氧化物(二氧化铈)改善硅橡胶热稳定性。研究了不同粒径、不同用量二氧化铈对硅橡胶耐热性的影响,并分析了填料对硅橡胶回弹性能的影响。     

丁苯胶/甲基丙烯酸锌/气相法白炭黑纳米复合材料

制备了三相纳米复合材料SBR／ZDMA／气相法白炭黑。采用了两种气相法白炭黑,U—fumed silica是一种未改性的气相法白炭黑,M—fumed silica是一种采用硅烷偶联剂Si69表面改性的气相法白炭黑。主要研究了气相法白炭黑和ZDMA之间的协同补强效应。研究结果显示,单独添加同样份数的改性气相法白炭黑和未改性气相法白炭黑对硫化胶物理机械性能的影响不同,改性气相法白炭黑的效果明显优于未改性气相法白炭黑。单独添加气相法白炭黑,体系的物理机械性能仍然维持在较低值。当同时添加气相法白炭黑和ZDMA时,会观察到明显的协同补强效应。交联密度和丙酮抽出试验表明对气相法白炭黑进行表面改性和在体系中添加ZDMA均会减弱气相法白炭黑表面羟基的影响。扫描电镜显示改性后气相法白炭黑在SBR中的分散性得到提高。在体系中添加ZDMA会提高气相法白炭黑的分散性。     

支链型乙烯基硅油改性有机硅灌封材料的性能

采用支链型乙烯基硅油改性的端乙烯基硅油为灌封硅橡胶的基础胶,并分别以沉淀法和气相法白炭黑进行补强,研究了不同用量和品种白炭黑补强对灌封材料的黏度、力学性能、粘接性能和电学性能的影响。结果表明,当401-1500/411-4800=100/15时,灌封材料黏度适中并且力学性能较好;沉淀法白炭黑加入量在20phr～25phr时,灌封材料具有较好的工艺性能,拉伸强度最大值达到2.27MPa,剪切强度最大值达到4.64MPa,电绝缘性良好。     

SiO2无溶剂纳米流体粒径和含量对环氧树脂力学和热性能的影响

为了改善纳米二氧化硅(SiO2)在树脂基体中的分散性,同时研究SiO2粒径对树脂基体性能的影响,采用St?ber法制备了50,90 nm和220 nm三种不同粒径的纳米SiO2,并通过表面接枝硅烷偶联剂及聚醚胺的方法制备了相应的SiO2无溶剂纳米流体(NF).利用红外光谱(FT-IR)、透射电镜(TEM)、热失重(TGA)和差示扫描量热法(DSC)等测试方法对流体的化学结构和物理形貌等理化性质进行了表征.测试了不同粒径和不同含量SiO2纳米流体/环氧树脂(NF/EP)复合材料的力学性能,结果表明,复合材料的力学性能随着流体含量的增加呈现先升后降的趋势;50 nm SiO2流体对环氧树脂冲击性能改善明显,当添加量为1 phr时,弯曲强度增加了11.64％,冲击强度增加了54.55％;而220 nm SiO2流体对弯曲性能改善更为明显,当添加量为1 phr时,弯曲强度提高17.51％,冲击强度提高50.00％.玻璃化转变温度和线膨胀系数测试的结果表明,NF/EP有更高的玻璃化转变温度和更低的线膨胀系数.NF/EP因具有良好的力学性能和低的线膨胀系数,可用作电子灌封树脂.     

无机填料对PVC/CPE/CB复合材料导电性能的影响

研究了具有不同粒子形态的无机填料(球形的纳米二氧化硅、片状的滑石粉和纤维状的玻璃纤维),以及不同粒径的碳酸钙(纳米碳酸钙、超细碳酸钙)对聚氯乙烯(PVC)/氯化聚乙烯(CPE)/导电炭黑(CB)复合材料导电性能的影响。电性能测试和扫描电镜形态结构分析结果表明,添加纤维状填料比球形和片状填料更有利于复合材料导电性能的保持;粒径较小的纳米碳酸钙对复合材料的导电性能影响较小。当炭黑含量为12phr时,添加15phr纳米碳酸钙后复合材料的电阻率仅为6.04×106Ω.cm。     

天然橡胶/顺丁橡胶共混胶体系裂纹生长行为的形态演变机理

研究了不同共混比例的顺丁橡胶(BR)与天然橡胶(NR)组成的共混胶的裂纹尖端生长行为。采用裂纹扩展在线研究平台(DMA-Crack Growth)、超高速摄像仪、扫描电子显微镜和扫描探针显微镜对裂纹尖端进行实时追踪观测,拍摄不同共混比例的橡胶裂纹尖端的裂纹扩展动态图像。结果表明,共混比例达到m(BR)/m(NR)=50/50时,韧带均匀分布在裂纹尖端,韧带多而细且均匀,可以有效减缓橡胶裂纹扩展速度;橡胶开裂的断面随着BR共混比例的增加,表面形貌由类三角形向扇形形貌过渡。最后讨论了裂纹增长的机理。     

接枝改性白炭黑对溶聚丁苯橡胶裂纹生长行为的影响

白炭黑是一种重要的橡胶填料,通过硅烷偶联剂改性,制备了不同接枝率白炭黑填充的溶聚丁苯橡胶。研究表明,接枝改性后白炭黑在橡胶基体中的分散得到改善,增强效果提升,裂纹生长速率随接枝率显著降低。进一步在动态载荷下对橡胶裂纹尖端进行正面观察其韧带生成、生长以及断裂的情况,发现随接枝率的提高,裂纹尖端韧带分布呈均匀化和细化的趋势。基于开裂形态与断裂面分析揭示了改性白炭黑填充溶聚丁苯橡胶抗裂纹生长能力提高的原因。     

单晶γ-TiAl中孔洞位置对裂纹扩展影响的分子动力学模拟

运用分子动力学方法对单晶γ-TiAl合金的裂纹扩展过程进行了研究,分析了不同孔洞位置对裂纹扩展的影响,得到相应的原子轨迹、能量演化以及应力-应变关系。结果表明无孔洞时,裂纹以脆性解理方式快速扩展至材料断裂,能量曲线只有一个波峰;L=1.6nm时裂纹先以脆性解理的方式扩展,孔洞抑制裂纹扩展,孔洞周围发射位错,裂纹以尖端空洞形核、长大成微裂纹,最终微裂纹与主裂纹连接的方式扩展,能量曲线有多个峰值;L=4.8nm时,裂纹初始扩展过程与L=1.6nm时相似,后期未出现空洞形核、长大成微裂纹并与主裂纹结合的现象;另外孔洞距裂尖距离不同,发射第一个位错的方向不同。     

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 ...     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

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