磁性膨胀石墨的制备及影响因素研究

采用柠檬酸盐溶胶-凝胶法, 以可膨胀石墨、硝酸铁、硝酸钴、柠檬酸为原料制备磁性膨胀石墨, 利用SEM、EDS、XRD和磁滞回线等对其微观形貌和磁性能进行了表征, 研究了原料配比、可膨胀石墨的pH值及膨胀时间对磁性膨胀石墨的磁性能和油吸附性能的影响. 综合磁性强度、油吸附性能及制备成本等指标, 得到最佳的制备条件为: 可膨胀石墨:铁氧体(ω/ω)=2:1, 可膨胀石墨的pH=5, 在900℃膨胀温度下膨胀时间为120s. 试验结果表明: 最佳制备条件 下, 铁氧体在膨胀石墨表面和层间沉积效果良好且分布均匀, 制备出的磁性膨胀石墨具有良好的磁性强度和油吸附性能, 其饱和磁化强度和油吸附容量分别为17.95A·m²·kg^-1和32.6g·g^-1.     

膨胀石墨复合材料的电磁特性及其3mm、8mm波动态衰减性能研究

通过高温下膨化二茂铁与可膨胀石墨混合物的方法, 制得附着铁氧化物的膨胀石墨复合材料. 铁氧化物的主要成分为Fe₂O₃、Fe₃O₄, 随着铁氧化物含量的增加, 其平均电导率呈下降趋势, 而磁化强度逐渐增强, 复合材料呈亚铁磁性. 在不影响膨胀石墨电损耗吸收的同时, 复合材料增加了磁损耗吸收, 其3mm、8mm波动态衰减效果明显优于单纯的膨胀石墨. 二茂铁和可膨胀石墨的质量比为2～3:5时, 3mm、 8mm波动态衰减能力最强.     

经化学镀铜改性膨胀石墨红外/毫米波衰减性能研究

为了提高膨胀石墨的红外/毫米波衰减性能,采用化学镀铜对可膨胀石墨进行表面金属化改性。通过对施镀温度、施镀时间、装载量等因素对增重率的影响,优化了镀铜工艺条件,并对改性后膨胀石墨进行分析表征及红外(3~5,8~14μm)、毫米波(3,8 mm)的衰减性能测试。结果表明,改性后的膨胀石墨表面均匀附着了少量的金属铜;XRD测试显示这些金属铜为微晶结构;在适当的装载量下改性后的镀铜膨胀石墨具有更好的红外、毫米波衰减性能。当装载量为15g/L时,镀铜膨胀石墨对3,8 mm和3~5,8~14μm波的衰减率较好,分别达88.96%,62.85%,82.25%和92.24%,相比未改性膨胀石墨分别提高了约10.34%,9.41%,6.56%和4.86%。     

等离子体法沉积磁性铁涂层及其电磁性能的研究

用铝金属作衬底、FeSO4溶液浓度为20~30g/L和电压130~150V采用等离子体沉积的方法可以制备出磁性铁涂层。XRD分析表明磁性涂层主要由单质铁结晶相组成。8℃,磁性铁涂层比饱和磁化强度达169.0A·m2/kg、剩磁为25.6A·m2/kg和矫顽力为35.34kA/m。磁性铁涂层的饱和磁化强度、剩余磁化强度和矫顽力随着测量温度的升高而降低。磁性铁涂层具有较好的雷达波吸收性能。     

碳纤维/石墨基电控离子分离NiHCF膜电极制备与表征

在碳纤维/石墨基体上通过毛细化学沉积法制备出具有高离子交换容量与高稳定性的铁氰化镍(nickel hexacyanoferrate,NiHCF)薄膜电极.采用循环伏安法考察了在石墨颗粒粒径100μm、PTFE含量0.05g/g石墨、乙醇量4ml/g石墨、制膜液浓度0.1mol/L(含1.07mol/L乙醇)条件下得到碳纤维/石墨基膜电极的离子交换容量、循环寿命与再生能力;并通过SEM、XPS分析了膜电极表面形貌、组成.研究结果表明,此多孔石墨基体电极比表面积大,沉积得到的NiHCF膜具有较大的离子分离能力、良好的循环稳定性与再生能力,可用于电化学控制离子分离(electrochemically controlled ion separation, ECIS)过程.     

铁钴镍合金粒子/石墨薄片复合材料的制备与吸波性能研究

利用超声和酸处理工艺将膨胀石墨剥离成纳米厚度的薄片,并利用简单的共沉积和退火还原工艺在石墨薄片上均匀沉积了铁钴镍磁性合金粒子.样品静磁性能与吸波性能的测试结果表明,此类材料具备优异的软磁性能和电磁波吸收性能.以600℃退火的Fe₃Co₆Ni/石墨薄片作为吸波剂的复合材料在12.6GHz处最大吸收可达-24dB,有效吸收带宽(<-5dB)达8GHz.通过调节合金的元素比例和退火工艺,可以控制样品的吸波性能.     

磁性金属Fe纳米线的制备及其性能

本文尝试采用纳米Au颗粒作为催化剂,利用化学气相沉积法合成铁纳米线。并着重研究了不同沉积温度对纳米线生长过程的影响。研究结果表明,过低沉积温度无法分解二茂铁,而过高沉积温度则会导致二茂铁高温分解副反应发生,生成大量碳颗粒,从而阻碍铁纳米线的生长。作者在600℃沉积温度下,以二茂铁为反应前驱体和蓝宝石作为基板,通过纳米Au颗粒的催化作用首次成功获得了大批量的铁单晶纳米线,并进一步揭示了纳米线的气-固生长机制。此外,本文还对合成的单晶Fe纳米线的磁各向异性进行了探讨。     

膨胀石墨的毫米波二维平面衰减性能研究

本文报道了不同长度膨胀石墨蠕虫的毫米波二维平面衰减实验结果 ,并将其与传统的微波干扰材料———铝箔条的毫米波衰减性能作了对比研究。结果表明 ,尽管膨胀石墨蠕虫在物理形状上与铝箔条有相似之处 ,并且具有一定的导电性能 ,但其对毫米波的衰减特性并不符合半波谐振子模型所推导出的结论。膨胀石墨蠕虫对毫米波的衰减为散射和吸收作用的综合结果。     

特大片鳞片石墨的分选及其制备的柔性石墨（英文）

为了保护近期中国发现的特大片鳞片石墨矿的超大鳞片不受分选加工过程的破坏,设计出"多破少磨+风选+分级磨浮"的联合工艺,对其进行了物理分选,采用碱熔+酸洗法进一步化学提纯,石墨插层化合物法制备出可膨胀石墨,并利用快速加热法得到膨胀石墨。结果显示,提纯后的特大片鳞片石墨的石墨化度高达99.9%,其膨胀石墨产品的膨胀体积高于400 mL/g,随机选取的膨胀石墨单个颗粒的长度大于40 mm,由此膨胀石墨轧制得的柔性石墨电导率高达2.78×10~5 S/m。     

膨胀石墨的毫米波二维平面衰减性能研究

本文报道了不同长度膨胀石墨蠕石的毫米波二维平面衰减实验结果，并将其与传统的微波干扰材料－铝箔条的毫米波衰减性能作了对比研究，结果表明，尽管膨胀石墨蠕虫在物理形状上与铝箔条有相似之处，并且具有一定的导电性能，但其对毫米波的衰减特性并不符合半波谐振子模型所推导出的结论。膨胀石墨蠕虫对毫米波的衰减为散射和吸收作用的综合结果。     

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.