二次水热法制备鸟巢状TiO2/Co3O4纳米结构及其锂电性能

以TiO_2粉末和NaOH为原料,在机械外力场作用下,采用水热法制备TiO_2纳米线。随后将得到的TiO_2纳米线与六水合硝酸钴(Co(NO_3)_2·6H_2O)和尿素(Urea)共同水热反应制备TiO_2/Co_3O_4纳米结构材料。分别利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、电池充放电测试仪和电化学工作站等,对材料的相组成、微观形貌、锂电性能和阻抗性能进行测试。结果表明,TiO_2/Co_3O_4纳米复合材料为鸟巢状结构,其在33.5mA/g电流密度下恒电流充放电的首次放电容量为777mAh/g,充电容量为759mAh/g,100次循环后的可逆容量仍保持在663mAh/g,具有良好的循环稳定性和电化学特性。     

正极材料LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2的表面包覆改性研究

采用沉淀法对镍钴猛锂正极材料(LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2)分别以氧化钇(Y_2O_3)、磷酸钇(YPO_4)、氧化铝(Al_2O_3)和磷酸铝(AlPO_4)行了表面包覆。采用X射线衍射光谱法(XRD)、扫描电子显微镜法(SEM)、电化学交流阻抗谱(EIS)及恒流充放电等方法表征了材料的结构、形貌及电化学性能。结果表明,包覆剂没有改变材料的晶体结构,可以均匀包覆在LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2材料表面,并且显著提高了材料的电化学性能。在2.5~4.5V电压范围和20mA/g电流密度下,包覆0.5%AlPO_4的材料首次放电容量为198.6mAh/g,50次循环后材料的放电容量保持到196.1mAh/g,而包覆Y_2O_3、YPO_4、Al_2O_3的材料其电化学性能均低于AlPO_4包覆材料。     

牺牲棉纤维模板法制备褶皱状SnO2负极材料及其电化学性能

以棉纤维作为模板, 制备褶皱层状SnO₂。通过XRD、SEM、TEM、CV、恒流充放电、EIS等测试手段对材料结构、形貌和电化学性能进行了表征。结果表明: 产物具有由粒径16~21 nm的SnO₂纳米颗粒构成的褶皱状形貌。电化学测试表明该材料在电流密度70 mA/g时循环50次后放电比容量仍高达614 mAh/g, 甚至在电流密度为3000 mA/g时放电比容量仍达到405 mAh/g, 表现出优异的循环性能和倍率性能。     

碳包覆空心Fe3O4纳米粒子作为锂离子电池负极材料的电化学性能研究

以二茂铁为铁源,石油渣油为碳源,通过加压热解和空气氧化制备了碳包覆空心Fe3O4纳米粒子。采用X射线衍射(XRD)、透射电镜(TEM)以及高倍透射电镜(HRTEM)等测试方法对样品的形貌和结构进行表征。采用恒流充放电和交流阻抗方法测试碳包覆空心Fe3O4纳米粒子作为锂离子电池负极材料的电化学性能。在电流密度为0.2mA/cm2时,首次放电比容量高达1294.7mAh/g,30次循环之后其放电比容量为392.1mAh/g;电流密度为1mA/cm2时,首次放电比容量为216.3mAh/g,30次循环之后其放电比容量为113mAh/g。     

MoP纳米粒子锂离子电池负极材料的制备及其电化学性能

用直流电弧等离子体法制备金属钼纳米粉体再使其与赤磷发生固相反应,用两步法制备出磷化钼纳米粒子。使用X射线衍射(XRD)和透射电镜(TEM)等手段表征磷化钼纳米粒子的结构并进行了电化学性能测试。结果表明,MoP纳米粒子呈球状,粒径为20~50 nm;在电流密度为100 mA/g的条件下MoP纳米粒子负极材料的首次放电比容量达到746 mAh/g,50次循环后放电比容量为241.9 mAh/g;电流密度为2000 mA/g时放电比容量为99.90 mAh/g,电流密度恢复到100 mA/g其放电比容量仍然保持247.60 mAh/g。用作锂离子电池的负极材料,MoP纳米粒子具有优异的稳定性和可逆性。     

Co_3O_4纳米片的制备及其电化学性能

以六水合硝酸钴[Co(NO_3)_2·6H_2O]为钴源、六次甲基四胺[CH_2)_6N_4]为水解剂,采用均相沉淀法制得β-氢氧化钴[β-Co(OH)_2]。β-Co(OH)2前驱体在400℃经煅烧2h制得四氧化三钴(Co_3O_4)材料。用X-射线衍射和扫描电镜对前驱体和目标产物进行了表征。结果表明,所得Co_3O_4为二维片状。电化学测试结果显示,Co_3O_4负极材料具有高的比容量和良好的循环性能。在100mA/g的电流密度下,首次充电比容量达到827mAh/g。恒流充放电50次后,容量保持率为88.5%。     

泡沫镍负载Co_3O_4纳米线制备及其超电容性能研究

以硝酸钴、尿素为原料,泡沫镍为基底,通过水热、煅烧法制备了Co_3O_4纳米线阵列,并采用扫描电子显微镜、透射电子显微镜及X射线衍射对Co_3O_4纳米线的微观形貌及晶体结构进行了分析。采用电化学工作站测试了Co_3O_4纳米线阵列作为超级电容器电极的电化学性能。结果显示:Co_3O_4纳米线阵列作为超级电容器电极材料在5mA/cm~2的电流密度下,具有高达1670F/g的比电容。同时显示出良好的倍率特性和较高的循环稳定性,应用前景良好。     

新型负极材料CrNbO_4的电化学性能研究及球磨改性

采用高温固相法制备CrNbO_4,并首次研究其作为锂离子电池负极材料的电化学性能。使用X射线衍射分析(XRD)、扫描电子显微镜(SEM)、充放电测试、循环伏安(CV)测试和电化学交流阻抗测试(EIS)对材料的结构、形貌和电化学性能进行表征。样品CrNbO_4在0.001~3.0V电压区间,电流密度为16 mA/g时,充放电50次后放电容量可以保持在63.5mAh/g。通过球磨,CrNbO_4的首次放/充电容量由212.9/100.9 mAh/g提高到572.3/343.5mAh/g,同时电流密度提高10倍,充放电50次后改性样品的放电容量仍可维持81.3mAh/g,有效提高了电化学性能。     

铁基普鲁士蓝正极材料的制备及储钠性能的研究

用简单的共沉淀法合成铁基普鲁士蓝正极材料,并研究合成温度对材料微观形貌和储钠性能的影响。研究结果显示,随着合成温度的提高,产物颗粒尺寸变大,钠含量增加。FeHCF-40℃电极材料,在30 mA/g电流密度下,首次放电比容量为132.3 mAh/g,循环100次后,放电比容量仍有102.4 mAh/g,容量保持率为77.4%;且当电流密度增大到1 500 mA/g时,仍可实现80.3 mAh/g的比容量,显示出优异的倍率性能和循环性能。     

碳芯结构LiFePO_4/C复合材料的表征及电化学性能

采用环氧树脂为碳源制备出碳芯结构LiFePO4/C复合材料.利用X射线衍射、扫描电镜、透射电镜和X光电子能谱等分别对复合材料的晶体结构、表面形貌及表面成分进行表征,采用恒电流充放电和电化学阻抗方法研究试样的电化学性能.实验结果表明:碳芯结构复合材料是由无定形碳线和纳米LiFePO4颗粒组成.碳芯结构LiFePO4/C复合材料在15mA/g的电流密度下,首次放电容量达到166mAh/g,当电流密度增加到750mA/g,放电容量高达131mAh/g,经过50次循环后,容量保持率高达99.2%.     

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.