癸酸与棕榈酸低共熔混合物的制备与热特性分析

在实验测得单一物质熔点和熔化潜热的基础上,利用低共熔混合物配比计算公式对癸酸和棕榈酸低共熔混合物的配比、熔点和熔化潜热进行了理论预测,以指导DSC测试,并对低共熔混合物进行了红外光谱试验,以判断是否有新相生成.实验结果表明,癸酸的熔点和熔化潜热分别为29.85℃和150.32J/g,棕榈酸的熔点和熔化潜热分别为62.13℃和210.13J/g.低共熔混合物的理论配比为85.7:14.3(质量比),相变温度为26.74℃,相变潜热为152.74J/g.低共熔混合物的配比为86.1:13.9(质量比),相变温度为25.39℃,相变潜热为153.58J/g,与理论计算结果较吻合.红外光谱试验结果表明,癸酸和棕榈酸混合物中没有新相生成.     

脂肪酸三元低共熔混合物相变温度和潜热的理论预测

对脂肪酸低共熔混合物相变温度和潜热的理论预测公式进行了选择和实验验证,通过DSC实验测试月桂酸-肉豆蔻酸二元低共熔混合物、月桂酸-肉豆蔻酸-棕榈酸三元低共熔混合物的热物性参数,发现理论预测公式对低共熔质量配比和相变温度的预测与实验结果吻合较好,可以用于计算脂肪酸类低共熔混合物的热特性参数。在此基础上对10种脂肪酸三元低共熔混合物的质量配比、相变温度和潜热进行了预测计算,这10种脂肪酸三元相变温度范围为16.12～38.86℃,相变潜热范围为154.99～177.39J/g。脂肪酸三元低共熔混合物的研究丰富了脂肪酸的相变温度和相变潜热范围,为脂肪酸类相变材料的工程应用提供了更广阔的空间。     

脂肪酸二元低共熔混合物相变温度和潜热的理论预测

对低共熔混合物相变温度和潜热的理论预测公式进行了选择和验证,对脂肪酸类二元低共熔混合物的配比、熔点和熔化潜热进行了理论计算。从实际的计算过程来看,计算值与实验值吻合得很好,可以用来计算脂肪酸类低共熔混合物的热特性参数。在15种脂肪酸类低共熔混合物中,熔点最低为10.2℃,最高为51.5℃;熔化潜热最低为138.6J/g,最高为187.5J/g。从工程实际应用来看,脂肪酸类低共熔混合物适用于低温采暖、生活热水、相变墙体、温控混凝土、相变服装等领域。     

超声化学沉淀法制备纳米NiO

以Ni(NO3)2·6H2O和(NH4)2C2O4·H2O为原料,采用超声沉淀法制备了纳米NiO,并利用XRD、FT-IR和TEM等分析方法对前驱体及产品组成和形貌进行了表征.结果表明,超声沉淀法制备的纳米NiO前驱体是二水合草酸镍.和实验制备的大颗粒Nio相比,纳米氧化镍Ni-O伸缩振动吸收峰及肩峰均发生了红移.纳米...     

液相制备纳米金属粉的粒度及形貌控制研究进展

纳米金属粉的粒度和颗粒形状决定其性能和应用,粒度和形貌的控制对纳米金属粉的制备至关重要.主要从纳米金属粉的粒度可控制备、形貌可控制备和复合结构纳米金属粉的制备3方面阐述了液相制备纳米金属粉的粒度和形貌控制研究现状;并总结了液相制备纳米金属粉的粒度和形貌控制作用机理.     

流延法制备SOFC NiO/YSZ阳极的研究

流延法制备了SOFC NiO/YSZ阳极,比较了NiO(微米级)和NiO(纳米级)两种NiO,发现由NiO(纳米级)制备的电池在800℃最大放电功率密度257.1mW/cm2,而由NiO(微米级)制备的电池相同条件下仅为124.9mW/cm2,原因在于NiO(纳米级)粒径小,制备的阳极三相反应区大.NiO(纳米级)经700℃煅烧后制备的电池最大功率密度增加到369.0mW/cm2,而 800℃和900℃煅烧时减少到169.5和159.0mW/cm2,因为700℃煅烧增加了NiO的活性,而800和900℃煅烧的NiO粒径增大到1.35μm,制备的阳极减小了反应活性区.YSZ在1200℃煅烧后,粒径从0.2μm增加到34μm,由于YSZ粒径远大于NiO,导致NiO之间接触不良,制备的电池性能下降到120.0mW/cm2,继续球磨12h后,YSZ粒径减小到0.70μm,NiO和YSZ之间分布均匀,制备的电池放电功率密度提高到447.9mW/cm2.     

NiO包覆Ni纳米颗粒的制备及其氧化特性研究

通过对直流电弧等离子体制备的Ni纳米颗粒钝化处理得到NiO包覆Ni纳米颗粒。并对试样的组成成分、形貌、晶体结构、粒度和氧化特性采用高分辨透射电子显微镜(HRTEM)、X射线衍射(XRD)、透射电子显微镜(TEM)和选区电子衍射(SAED)、热重和差示扫描量热分析仪(TGA/DSC)等手段进行分析。结果表明:经过表面钝化处理的NiO包覆Ni纳米颗粒具有明显的核-壳结构,内核为纳米Ni,外壳为NiO氧化物。颗粒呈球形,粒度均匀,分散性良好,粒径分布在20~70nm范围内,平均粒径为44nm,壳层氧化膜的厚度为5~8nm。壳核结构防止了纳米Ni颗粒的进一步氧化和团聚。     

均匀沉淀法制备纳米氧化镍的正交实验研究

以Ni(NO3)2·6H2O和CO(NH2)2为原料,采用均匀沉淀法制备了纳米氧化镍(NiO).同时,利用正交实验探讨了不同工艺参数对合成纳米NiO的影响,并得出了最佳工艺条件.实验得出的最优工艺参数为:反应温度115℃,尿素对镍盐的物质的量之比为4:1,反应时间2.5h.产品分析表明,最佳工艺条件下所制备的纳米NiO呈球形,分散性良好,纯度较高,属立方晶系结构,平均粒径约为8nm.     

纳米SiO2对静电纺LA-PA/PET复合相变纤维形态和热学性能的影响

以月桂酸和棕榈酸二元低共熔混合物(LA-PA)、聚对苯二甲酸乙二酯(PET)和纳米二氧化硅(SiO2)为原料,通过静电纺丝的方法成功制备了新型的LA-PA/PET/SiO2定形相变复合纤维。分别采用扫描电子显微镜(SEM)和差示扫描量热仪(DSC)研究了纳米SiO2对静电纺LA-PA/PET/SiO2复合相变纤维的形貌结构和热学性能的影响。SEM观察结果显示,随着纳米SiO2的加入,复合相变纤维表面呈现出光滑的形态特点,纤维直径有所降低;且随着纳米SiO2含量的增加而逐渐减小。DSC分析结果表明纳米SiO2的含量对复合相变纤维的熔化焓值和结晶焓值有一定的影响,对相变温度没有显著性的影响。     

多孔NiO纳米棒:可牺牲模板法制备及其磁性(英文)

本文基于微乳液法制备了长度几微米、直径20-100纳米的NiC2O4纳米棒,以此为可牺牲模板得到多孔NiO纳米棒,并采用FESEM、TEM、HRTEM、XRD、FTIR对产物的形貌和结构进行了表征。研究表明,所制多孔NiO纳米棒是由NiO颗粒组成,且NiO颗粒的直径可随热处理温度变化。同时研究了NiO纳米棒的磁性性能,制备的NiO纳米棒显示出随NiO颗粒尺寸变化的铁磁性特征。     

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.