水热组装法制备碳纳米管网状支撑氮掺杂多孔碳材料及其储能特性研究

采用水热组装法制备了碳纳米管/氮掺杂多孔碳复合电极材料。通过扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、拉曼光谱(Raman)、N2吸附-脱附(BET)和X射线光电子能谱(XPS)表征了复合材料的微观形貌和结构;并采用循环伏安法、恒流充放电和交流阻抗谱测试了复合材料的储能特性。结果表明,水热组装法成功地合成了具有高比表面积(1 039m~2/g)的碳纳米管/氮掺杂多孔碳复合材料。并且该复合材料表现出优异的储能特性,在1A/g下,其比电容高达261F/g,远远高于氮掺杂多孔碳(214F/g)和碳纳米管(109F/g)的比电容;在功率密度为10 500 W/kg下其能量密度仍为53.75 Wh/kg。     

碳纳米管增强2024铝基复合材料的力学性能及断裂特性

为了研究碳纳米管对铝基复合材料性能的影响,采用冷等静压、热挤压方法制备了质量分数1.0%的多壁碳纳米管增强2024Al基复合材料.采用扫描电镜、透射电镜和拉伸试验对复合材料的显微组织进行了观察和分析,并对其力学性能进行了测试.结果表明,碳纳米管均匀地分布在复合材料中,碳纳米管和铝基体的界面结合良好,没有发现界面产物Al4C3的形成;复合材料的断口上存在大量的撕裂棱,韧窝,并涉及碳纳米管的拔出或拔断与桥接,与2024Al基体材料相比,复合材料的硬度、弹性模量和抗拉强度显著提高,同时复合材料的延伸率却并不下降.碳纳米管的加入可以显著提高铝基复合材料的力学性能.     

搅拌摩擦加工法制备碳纳米管增强铝基复合材料

为了制备晶粒细小、 组织均匀的复合材料, 提高材料的力学性能, 用搅拌摩擦加工法制备碳纳米管增强铝基复合材料, 并对不同碳纳米管含量的复合材料的微观结构、 拉伸性能及断口形貌进行分析。结果表明: 碳纳米管添加到铝基体中, 搅拌摩擦中心区晶粒细小, 碳纳米管与基体之间结合良好, 未发现明显的缺陷; 碳纳米管对基材有明显的强化作用, 铝基复合材料抗拉强度随着碳纳米管含量的增加而提高; 碳纳米管体积分数为7%时, 抗拉强度达到201 MPa, 是基材的2.2倍; 复合材料在宏观上呈现脆性断裂特征, 微观上呈现韧性断裂特征, 其断裂机制以CNTs/Al界面脱粘、 基体撕裂和增强体断裂为主。      

填料对聚丙烯导热复合材料导电和流变性能的影响

分别制备了炭黑、碳纳米管、炭黑/碳纳米管简单共混以及炭黑碳纳米管化学键合聚丙烯复合材料,研究了不同体系的导热、导电和流变性能。研究发现,使用炭黑/碳纳米管简单共混或化学键合掺杂的复合材料热导率分别达到0.60W/mk和0.63 W/mk,而使用炭黑或碳纳米管杂化的组分热导率仅仅为0.36 W/mk和0.45 W/mk。掺杂碳纳米管或炭黑/碳纳米管简单共混填料的复合材料体积电阻下降了6个数量级,而掺杂炭黑或炭黑/碳纳米管化学键合填料的复合材料均有较好的绝缘性。掺杂杂化组分后,复合材料均出现了剪切变稀现象,在储能模量与频率曲线上低频区出现"第二平台",但掺杂炭黑/碳纳米管化学键合样品的第二平台极微弱。微观结构发现填料在基体中分散良好,填料间形成了很好的架桥。研究结果表明,简单使用炭黑、碳纳米管掺杂对复合材料的热导率改善不佳,使用炭黑/碳纳米管简单混合虽能大幅提高热导率,但影响复合材料的绝缘性能,而将炭黑/碳纳米管化学键合后可满足制备导热绝缘复合材料的要求。     

碳纳米管增强铝基复合材料的界面研究进展

碳纳米管以其稳定的结构、优异的力学性能,成为复合材料的理想增强相。其增强效果受多方面因素影响,界面是决定其增强效果的关键因素之一,也是金属基复合材料的研究重点。简要介绍了碳纳米管增强铝基(CNTs/Al)复合材料的界面结合机制及界面对复合材料性能的影响,评述了热膨胀系数、制备方法、碳纳米管纯度等多种因素对CNTs/Al复合材料界面的影响,并提出了改善界面的方法。     

碳纳米管增强铝基复合材料分散方法研究进展

碳纳米管与铝基体的结合,可以获得导电和导热性良好及综合力学性能优异的复合材料,有望成为新一代轻质高强、结构功能一体化的复合材料.在制备碳纳米管增强铝基复合材料过程中,碳纳米管的团聚将降低界面结合,诱发缺陷产生,导致性能大幅下降,因此,调控优化碳纳米管的分散状态、含量成为获取良好界面结合,获得高性能碳纳米管增强铝基复合材...     

碳纳米管/陶瓷基复合材料研究进展

介绍了碳纳米管的结构、制备、处理及性能,综述了碳纳米管/陶瓷基复合材料的制备方法以及碳纳米管/陶瓷基功能复合材料的研究进展,并对复合材料制备中碳纳米管的分散、取向与阵列、烧损和复合材料的界面等问题进行了分析.     

CNTs/AZ91碳纳米管镁基复合材料的制备及性能研究

为了研究加入碳纳米和铝含量不同以及不同热处理方式对镁基复合材料机械性能和组织结构的影响,采用搅拌铸造法制备了碳纳米管增强镁基复合材料(CNTs)/AZ91,测试复合材料在铸态T4态和T6态的机械性能,并对材料的微观组织进行观察和分析,研究发现加入碳纳米管后材料强度有所提高,然而塑性却下降了,同时碳纳米管能明显细化复合材料微观组织。当铝含量增加时,复合材料的弹性模量有所提高,而合理的热处理则使复合材料的机械性能有所提升,为生产及科研提供了参考依据。     

两亲性聚合物/碳纳米管复合材料的研究进展

两亲性聚合物具有独特的pH/温度响应、自组装等特性,将其与碳纳米管结合制成的两亲性聚合物/碳纳米管复合材料具有广阔的应用前景.介绍了两亲性聚合物/碳纳米管复合材料的3种制备方法,即原子转移自由基聚合法、可逆加成一断裂链转移自由基聚合法和氮氧自由基聚合法,综述了两亲性聚合物/碳纳米管复合材料在两亲性、pH/温度响应性等方面的应用进展.     

两亲性聚合物/碳纳米管复合材料的研究进展

两亲性聚合物具有独特的pH/温度响应、自组装等特性,将其与碳纳米管结合制成的两亲性聚合物/碳纳米管复合材料具有广阔的应用前景.介绍了两亲性聚合物/碳纳米管复合材料的3种制备方法,即原子转移自由基聚合法、可逆加成-断裂链转移自由基聚合法和氮氧自由基聚合法,综述了两亲性聚合物/碳纳米管复合材料在两亲性、pH/温度响应性等方面的应用进展.     

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.