纳米ZnO对MC尼龙结构和性能的影响

采用原位聚合反应制备了纳米ZnO/MC尼龙6复合材料。对所制备的复合材料进行力学性能、 形貌、 结构检测及DSC、 XRD分析, 结果表明: 复合材料中的ZnO粒径小于100nm, 分布均匀; 纳米ZnO/MC尼龙6复合材料拉伸强度比纯MC尼龙6提高20%; 断裂伸长率提高33%; 弯曲模量提高36%; 冲击强度提高87%。纳米ZnO的加入对α晶型的衍射特征峰影响不大, 不改变尼龙6的结晶形态, 但使晶粒度加大, 结晶度减小; 动态高温XRD分析表明, 加入纳米ZnO, 能提高MC尼龙融熔温度, 纳米ZnO/MC尼龙6复合材料的结晶形态和相对结晶度在高低温度间基本是可逆的。      

ZnO粒径对MC尼龙/纳米ZnO复合材料力学性能的影响

用三种粒径范围的纳米ZnO合成MC尼龙/ZnO复合材料。考察了纳米ZnO的粒径对复合材料力学性能和在复合材料中的分散状况的影响。研究表明,平均粒径为30nm的ZnO合成的MC尼龙/纳米ZnO复合材料中ZnO粒子达到纳米级分散,粒子分布均匀,ZnO对MC尼龙的力学性能提高幅度最大,增强增韧作用非常明显;平均粒径为200nm的纳米ZnO在复合材料中,虽然粒径较大,但分散较均匀,无明显团聚,ZnO对MC尼龙的力学性能也有一定的提高,但提高幅度不大;平均粒径为60nm的ZnO分散难度大,ZnO在复合材料中既有小颗粒的分散,也有大颗粒的团聚体,使材料的力学性能明显不如前两种复合材料。     

MC尼龙和MC尼龙/纳米ZnO复合材料晶面间距的膨胀系数和收缩系数

采用原位聚合反应制备铸型(MC)尼龙6/纳米ZnO复合材料,并用动态高温X射线衍射(XRD)法对合成的MC尼龙/纳米ZnO复合材料进行研究,考察其在升温和降温过程中α<,1>和α<,2>晶面间距的变化、结晶结构的热稳定性.结果表明,随着温度的升高,MC尼龙的α<,1>(200)和α<,2>(002+202)晶面分别发生...     

合成条件对Bi_2MoO_6/ZnO纳米复合材料光催化性能的影响

采用水热法在不同的反应温度、反应时间和不同pH值条件下原位合成纳米Bi_2MoO_6/ZnO复合材料,使用XRD,SEM分析了产物的相结构与微观相貌,通过Bi_2MoO_6/ZnO光催化降解亚甲基蓝溶液,分析复合物的光催化性能。研究结果表明,在pH=6、反应温度为160℃、反应时间为12 h的条件下,可以得到结晶度较高的Bi_2MoO_6/ZnO纳米复合材料,且在可见光照射条件下90 min,对亚甲基蓝的降解率最大达到97.6%。Bi_2MoO_6/ZnO纳米复合材料在光降解领域具有潜在应用价值。     

碳纳米管掺杂ZnO复合材料的乙醇气敏特性研究

采用简单的一步式水热法制备了颗粒状纳米ZnO,以纳米ZnO为基体材料通过球磨法进行碳纳米管(CNTs)掺杂制备CNTs-ZnO复合材料，研究了改变CNTs含量(1%、3%、5%)对ZnO传感器气敏性能的影响。结果表明：通过CNTs掺杂，ZnO传感器的灵敏度得到大幅度提高且工作温度呈现降低的趋势，其中3%-CNTs/ZnO复合材料在最佳工作温度360℃下对乙醇浓度为100×10^-6的响应值(S=R_a/R_g)为98.329,是纯纳米ZnO的2.5倍。优异的性能主要归因于CNTs的掺杂增加了CNTs-ZnO复合材料的比表面积，而且可以促进CNTs在ZnO界面形成p-n异质结。     

Gd_2O_3/MC尼龙纳米复合材料的制备及性能研究

用原位分散聚合法制备了一系列Gd2O3/ME尼龙纳米复合材料,用SEM观察了Gd2O3纳米粒子在MC尼龙基体中的分散情况,用XRD研究了复合材料的晶体结构,并对复合材料的力学性能进行了表征.研究结果表明:(1)用原位分散聚合法制备Gd2O3//ME尼龙纳米复合材料是可行的,Gd2O3纳米粒子均匀分散在MC尼龙基体中,团聚情况较少;(2)GD2O3纳米粒子没有改变MC尼龙的结晶形态,但使其晶格尺寸发生了一定程度的改变;(3)纳米Gd2O3的加入可明显改善MC尼龙的力学性能,对MC尼龙同时具有增强和增韧双重效果.随着纳米Gd2O3用量的增加,复合材料的拉伸强度、断裂伸长率、缺口冲击强度、弯曲强度和弯曲模量都呈先升后降的趋势.当纳米Gd2O3用量为0.5%时,复合材料的综合性能最好,其拉伸强度、断裂伸长率、缺口冲击强度、弯曲强度和弯曲模量分别比MC尼龙基体提高19.6%、47.2%、19.7%、9.3%%和11.7%.     

MC尼龙/Dy_2O_3纳米复合材料的制备及性能研究

用原位分散聚合法制备了MC尼龙/Dy2O3纳米复合材料,采用SEM、XRD、力学性能测试等对复合材料进行了分析。研究表明,加入少量纳米Dy2O3可明显改善MC尼龙的力学性能和耐磨性,起到同时增强、增韧和耐磨的作用,当纳米Dy2O3的用量为0.5%时,复合材料的拉伸强度和断裂伸长率达到最大值,分别比MC基体提高15.9%和49.3%,当纳米Dy2O3的用量为1.0%时,复合材料的缺口冲击强度达到最大值,比MC尼龙提高26.8%,磨耗体积达到最小值,比MC尼龙降低84.6%。     

稀土氧化物/MC尼龙纳米复合材料的制备及性能研究

用原位分散聚合法制备了一系列稀土氧化物(La2O3、Sm2O3、Nd2O3、Gd2O3、Dy2O3)/MC尼龙纳米复合材料,用SEM观察了稀土氧化物纳米粒子在MC尼龙基体中的分散情况,用XRD研究了复合材料的晶体结构,并对复合材料的力学性能进行了表征.研究结果表明:用原位分散聚合法制备稀土氧化物/MC尼龙纳米复合材料是可行的,稀土氧化物纳米粒子均匀分散在MC尼龙基体中,团聚情况很少;稀土纳米氧化物没有改变MC尼龙的结晶形态,但使其晶格尺寸发生了一定程度的改变;稀土纳米氧化物可显著改善MC尼龙的力学性能,对MC尼龙同时具有增强和增韧的双重效果.     

纳米ZnO填充乙烯-醋酸乙烯酯共聚物的动态流变行为

为提供纳米ZnO/乙烯-醋酸乙烯酯共聚物(EVA)复合材料加工及性能优化的理论依据,通过熔融共混法制备了纳米ZnO/EVA复合材料,采用DSC研究了复合材料的熔融结晶行为,采用旋转流变仪分析了纳米ZnO质量分数以及偶联剂表面处理对复合材料体系动态流变行为的影响。结果表明:随着纳米ZnO质量分数的提高,纳米ZnO/EVA复合材料的结晶温度和熔融温度均先上升后下降;但改性纳米ZnO质量分数对改性纳米ZnO/EVA复合材料的熔融温度和结晶温度影响不大。当纳米ZnO的质量分数大于20%时,纳米ZnO/EVA体系的复数黏度发生突变,储存模量-角频率曲线在低频区出现第二平台,对应于应变扫描曲线上出现的两段线性黏弹区域,表明因纳米ZnO粒子间相互关联、团聚及粒子与基体间的相互作用形成了局部有序的逾渗网络结构;而纳米ZnO经偶联剂表面处理后,体系的复数黏度下降,储存模量-角频率曲线没有出现平台,说明改性纳米ZnO在复合材料体系中分散得更加均匀。研究表明偶联剂对纳米ZnO的表面处理改善了纳米ZnO在EVA中的分散性。     

不同形貌聚苯胺/氧化锌复合材料的制备与光催化性能EI北大核心CSCD

通过水热法制备了球形、棒状和花形的纳米氧化锌;并利用原位聚合法制备了对应形貌的氧化锌/聚苯胺复合材料。用X射线衍射(XRD)、热重分析(TG-DTG)和扫描电镜(SEM)等测试手段,对氧化锌及复合物进行了结构表征。以次甲基蓝为模拟污染物,在紫外灯下考察了复合物材料的光催化性能和动力学特征。结果表明,聚苯胺(PANI)/氧化锌(ZnO)复合材料的光催化性能远高于纯纳米ZnO,而不同形貌的PANI/ZnO其光催化降解效率也不同,依次为球形>棒状>花形;PANI/ZnO(球形)的失水温度和分解温度与纯PANI相比分别提高了123.3℃和47.6℃。光催化动力学研究表明,以球形和棒状氧化锌为原料制备的PANI/ZnO复合材料符合一级动力学,PANI/ZnO(花形)复合物符合二级动力学。     

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