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...     

超声波化学法制备纳米铁酸锌粉末的影响因素

超声辐射Fe(NO3)3·9H2O、不同锌盐和脲的混合水溶液得到前驱体,再经过高温焙烧得到纳米ZnFe2O4粉末.得到的纳米ZnFe2O4粉末用X射线衍射(XRD),傅立叶转换红外光谱(FT-IR)表征得到确认.系统研究了超声波化学法制备纳米铁酸锌粉末工艺中不同锌盐、超声波辐射时间、焙烧温度和焙烧时间等影响因素,结果表明:Fe(NO3)3·9H2O与Zn(NO3)2·6H2O为原料,超声波辐射为4h,焙烧温度为950q℃,焙烧时间为14h可制备结晶良好、分散性好、粒度小于100nm的尖晶石型铁酸锌粉末.     

液相包覆法合成Ba(Mg1/3Ta2/3)O3超细粉体

以水合五氧化二钽(Ta2O5·nH2O)纳米胶粒为活性固相基体,柠檬酸镁、柠檬酸钡混合溶液为包覆相,采用液相包覆-界面反应的方法制备Ba(Mg1/3Ta2/3)O3超细粉体.利用热失重-差热分析、X射线衍射及透射电镜等手段对产物的合成过程与结构形态进行了分析表征.研究表明以该方法能够在800℃下合成出成分均一、纯度较高、具有良好烧结活性的BMT超细粉体,产物粒子的形态接近球形,粒径分布窄,大约为20～30nm.     

溶液雾化焙烧法制备氧化亚镍超细粉体

为研究雾化焙烧法制备氧化亚镍超细粉体过程原理与工艺控制,以六水合氯化镍配制水溶液,以压缩空气为载气,利用双通道内混合气流式喷嘴雾化前驱体溶液,获得微细雾滴直接在竖立管式高温电阻炉内焙烧,制备得到超细氧化亚镍粉体.采用热重-差热分析(TGA-DTA)对NiCl2·6H2O在空气气氛中的热行为进行研究,利用X射线衍射分析(...     

1,2,3,4-丁烷四羧酸锌络合物的合成及其热分解制备纳米氧化锌

用ZnSO4与1,2,3,4-丁烷四羧酸四钠盐反应制备了1,2,3,4-丁烷四羧酸锌络合物.元素分析和热重分析结果表明络合物的分子式为Zn2(C8H6Os)·2H2O.红外光谱分析结果证实Zn2(C8H6O8)·2H2O配合物生成.热重分析结果表明Zn2(C8H6O8)·2H2O的起始分解温度为400℃.研究了其热分解制备纳米氧化锌的新途径.TEM分析表明在400℃C下焙烧Zn2(C8H6O8)·2H2O所得到的氧化锌晶粒尺寸为20～60nm.     

草酸盐法制备硼酸镁晶须及其生长机理

以MgCl2·6H2O、H3BO3和H2C2O4·2H2O为原料,利用草酸盐法制备出长度为4.0～8.0μm,直径为0.6～1.5μm,长径比约为10,形貌良好的硼酸镁晶须。采用XRD、SEM及TG-DTA等分析手段,研究了烧结温度、烧结时间、n(B)/n(Mg)、n(H2C2O4)/n(Mg)对硼酸镁晶须的生长过程和质量的影响,探讨了其最佳制备条件。结果显示,硼酸镁晶须的最佳制备条件为:烧结温度为800℃,烧结时间为4.0h,n(B)/n(Mg)=1.2,n(H2C2O4)/n(Mg)=1.2。根据XRD和TG-DTA分析,MgC2O4前驱体对硼酸镁晶须的形成和生长有较大的促进作用,分解产物不引入其它杂质,使得制备的晶须纯度较高。晶须的生长机理为S-L-S机理。     

共沉淀制备不同粒径Fe3O4纳米颗粒及磁性能的研究

以氯化铁(FeCl3·6H2O)和氯化亚铁(FeCl2·4H2O)为原料,氢氧化钠(NaOH)为沉淀剂,在无表面活性剂作用下共沉淀制备出了不同粒径的Fe3O4纳米颗粒.采用X射线衍射(XRD)、透射电子显微镜(TEM)和振动样品磁强计(VSM)对产物的晶体结构、形貌、粒径及磁性能进行了表征.实验结果表明,n(Fe2+)...     

VOC2O4·H2O热分解制备纳米VO2粉体及相变特性

提出了一种采用草酸氧钒(VOC2O4·H2O)热分解制备纳米VO2的方法.通过热分析(TG-DSC)、XRD和TEM手段,分析了草酸氧钒前驱体的热分解过程,纳米VO2的结构和形貌,测定了纳米VO2粉体的电阻-温度曲线.实验结果表明VOC2O4·H2O热分解开始温度为343℃,在380℃,真空度为20～50Pa的条件下,热分解获得VO2的平均尺寸为22nm,相变温度为69℃.     

TiO2/Mn2O3复合纳米纤维的制备及光吸收性能研究

以聚乙烯吡咯烷酮(PVP)为络合剂,与钛酸四正丁酯 Ti(C4H9O)4]和醋酸锰(Mn(CH3COO)2·4H2O)反应制得前驱体溶液,用静电纺丝法制备PVP/TiO2/Mn2O3纳米复合纤维,在马弗炉中经过煅烧处理过程,获得了TiO2/Mn2O3纳米纤维.采用扫描电镜(SEM)、热分析仪(TG-DTA)、X射线衍射...     

纳米Ni0.5Zn0.5Fe2O4铁氧体的制备及电磁损耗特性研究

采用NH4 HCO3与FeCl3·6H2O、Zn(NO3)2·6H2O、Ni(NO3)2·6H2O进行室温固相反应制得Fe(OH)3、Zn3(OH)4CO3·H2O、Ni3(OH)4CO3·4H2O混合前驱物,先经微波加热,再热分解制得纳米粉体.利用激光粒度分析仪、XRD、SEM和TEM对分解产物进行了表征,获得了形貌为球形、颗粒分布均匀、平均粒度为62nm、尖晶石结构的纳米Ni0.5Zn0.5Fe2O4复合铁氧体粉体.经测试样品的相对介电常数和相对磁导率后,发现该纳米铁氧体粉体在100～1800MHz内具有良好的电损耗和磁损耗性能.     

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.     

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...     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.     

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.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.