制备工艺对纳米级铟锡氧化物(ITO)形貌和电性能的影响

以SnCl4·5H2O、In和浓盐酸为原料,采用化学共沉淀法制备出了纳米级锡掺杂氧化铟(ITO)导电微粉,系统地研究了掺杂量,共沉淀温度,pH值,热处理时间、温度对粉体粒度、形貌和电性能的影响规律。研究表明,合成的ITO粉体分散性较好、导电性能优异,粒径在40nm左右具有立方铁锰矿结构。在ITO纳米导电粉的制备过程中,共沉淀温度和滴定终点pH值对其形貌和性能有很大影响,当共沉淀温度在60℃左右,pH=6时制得的粉体性能最佳。煅烧条件对粉体的形貌、粒度和导电性也有较大的影响,在700℃,4h条件下可以制得导电性能良好,结晶完好,粒度分布均匀的ITO粉体。掺入Sn(Ⅳ)的量对载流子的迁移率有很大的影响,在掺杂浓度为10%左右可制得导电性极佳的纳米ITO粉体。     

纳米γ-Fe_2O_3的室温固相反应工艺研究

采用室温固相法合成了γ-Fe2O3的前驱体FeC2O4·2H2O及纳米γ-Fe2O3。以FeSO4·7H2O和H2C2O4·2H2O为原料,先得到了前驱体FeC2O4·2H2O,通过对反应机理的初步探讨,并研究其物质结构、分解过程和合适煅烧温度,最后在400℃下煅烧前驱体3h得到γ-Fe2O3纳米粒子。经热重(TG-DTA)、X射线衍射(XRD)和透射电镜(TEM)测试手段的分析,结果表明:室温固相法合成纳米γ-Fe2O3产物γ-Fe2O3纯净、粒子为纳米级且分布均匀。     

Bi2O3-Y2O3体系中纳米δ-Bi2O3相的生成规律研究

以分析纯的Bi(NO3)3·5H2O和Y (NO3)3*6H2O作为原料,经反向滴定法化学共沉淀、干燥和430℃焙烧后获得(75mol%Bi2O3+25mol%Y2O3)纳米复合粉体,粉体平均粒度30nm以下;通过常压反应烧结工艺制备了纳米Bi2O3-Y2O3快离子导体,对烧结过程中高导电相(纳米δ-Bi2O3)的形成规律研究结果表明烧结初期以固溶反应为主,后期以晶粒长大为主,晶粒生长规律符合(D-D0)2=K·t抛物线方程;用模式识别技术对δ-Bi2O3相生成的工艺条件进行了优化.     

己二酸直接沉淀法合成超细二氧化钛粉体

以TiCl4和己二酸为原料，在适当的PH值下，合成Ti2O2（OH）2C6H8O4·1．5H2O前体，经洗涤，干燥，煅烧，得到超细二氧化钛粉体。讨论了煅烧温度，煅烧时间，分散剂和干燥方法等因素对二氧化钛粉体粒度的影响。通过对所得粉体的形貌，颗粒尺寸分析，得出制备超细二氧化钛工艺条件为：添加聚乙二醇作分散剂，微波干燥前体，在500℃下煅烧0．5h，得平均粒径为30nm且粒度分布均匀的粉体。     

溶剂热-煅烧法合成纳米ITO粉体

本文采用溶剂热-煅烧法制备纳米铟锡复合氧化物(ITO).以In(4N)、SnCl4·5H2O为起始原料,通过XRD、SEM及微波吸收性能的分析,考察了溶剂热反应中溶剂对ITO粉体结构及性能的影响.研究表明以1,4-丁二醇为溶剂,KBr为矿化剂(浓度0.5mol/L)在260℃下醇热6h,得到结晶性良好的羟基氧化铟和锡掺杂氧化铟的混合物.溶剂热产物在550℃下煅烧2h得到纳米ITO粉体,醇热-煅烧产物的吸波性能良好.     

化学沉淀法制备纳米氧化铝过程中的防团聚研究

分别以无水乙醇、去离子水为溶剂，以NH3·H2O、NH4HCO3为沉淀剂，采用化学沉淀法制备了纳米Al2O3粉体。利用TEM、XRD、nIR和激光粒度仪研究了溶剂、沉淀剂、浓度、前驱体等因素对纳米Al2O3粉体制备过程中的团聚程度的影响。结果表明：当NHaHCO3和Al（NO3）3水溶液浓度分别为3．0mol／L和0．3mol／L时，借助超声分散和微波干燥，得到的纳米Al2O3粉体粒度均匀、分散良好，1100℃煅烧所得粉体平均粒径为20nm。     

苹果酸络合物沉淀法制备纳米二氧化钛粉体

提出了一种苹果酸络合物沉淀法制备高纯纳米二氧化钛粉体方法。使含有适量表面活性剂的Ti4+与C4H4O52-反应生成苹果酸钛络合物前驱体Ti2O2(OH)2C4H4O5·4H2O,经洗涤、干燥,在900℃下煅烧2h,得到纳米TiO2粉体。经XRD和TEM检测,产物纳米二氧化钛为金红石型结构,平均粒径为40nm。     

一种制备氧化镁纤维的方法

尝试以廉价的MgCl2·6H2O和NH3·H2O为原料,通过"假象"工艺制备氧化镁纤维.制得了结晶良好、具有纤维状外形的Mg2(OH)aCl·3H2O单一物相.借助纤维状中间体,采取分段煅烧工艺,即通过控制低温分解条件使之保持原来的晶体形貌,而通过高温处理使纳米MgO颗粒进一步团聚、长大、烧结得到氧化镁纤维.利用SEM和XRD对产物进行了表征,MgO纤维是由纳米氧化镁颗粒烧结而成的"假象"体,直径在0.3-1.2μm之间,长度>50μm.最佳分解温度为873K,最佳煅烧温度1273K.     

纳米氧化铝粉体的绿色合成及其物相转变控制研究

以氯化铝、碳酸钠为原料,采用直接沉淀法,并于500～1,200℃煅烧,制备纳米Al2O3粉体。然后用TiO2、BaO对纳米Al2O3粉体掺杂,控制其物相转变过程。通过X射线衍射仪、差式扫描量热仪和透射电子显微镜分析纯净和掺杂后的纳米Al2O3的物相转变过程。结果表明,直接沉淀法所得水合Al2O3,经500℃煅烧后可转变为纳米活性Al2O3,粒径约为10 nm;纯净和掺杂Al2O3样品经1,200℃煅烧2 h后均为纳米粉体,其粒径为40～50 nm;在较高温度下,掺杂氧化钡对Al2O3的物相转变具有强烈抑制作用,粉体直至1,200℃仍未转变为结晶良好的α-Al2O3物相;而氧化钛则对其物相转变有显著促进作用,在1,000℃时粉体的主要物相即为α-Al2O3,1,100℃之后粉体已完全转变为α-Al2O3。     

醇-水法制备纳米晶NiO粉体

Ni(NO3 ) 2 ·6H2 O和NH4HCO3 在醇 水溶液中反应合成NiCO3 · 2Ni(OH) 2 ·2H2 O前驱体 ,经煅烧后得到大约 10nmNiO粉体。同传统的水溶液法相比 ,醇 水法得到的NiO粉体粒径尺寸小、分布范围窄和团聚少 ,PEG的添加能够减少团聚     

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.     

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...     

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.     

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.     

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 ...