纳米四方多晶氧化锆粉体的低温制备及反应机理研究

采用引入有机添加剂的低温超强碱法制备出纳米四方多晶氧化锆粉体.采用X射线荧光光谱、X射线衍射、透射电镜对粉体物相组成和微观结构进行了分析.结果表明,有机添加剂-低温超强碱法在反应初期氧化锆晶核就已经形成,这与普通的湿化学法显著不同;同时有机添加剂的引入,在反应开始就减少了粉体的团聚,利于获得分散性好的高质量粉体;所制备的粉体具有粒度小、粒度均匀和分散性好等特点;该方法具有低温高效节能的特点.     

均相沉淀-发泡法制备纳米氧化锆材料的研究

以ZrOCl2·8H2O和尿素为原料,利用均相沉淀发泡工艺制备出了纳米氧化锆粉体材料,并用差热热重(DTATG)、X射线衍射(XRD)、比表面和孔隙度(ASAP)和透射电镜(TEM)等方法对样品进行了表征。结果表明,在600℃下焙烧的氧化锆样品为纯度较高的纳米四方多晶氧化锆粉体,属于介孔材料,氧化锆粉体粒度较均匀、分散性好且平均粒径约为5nm。     

X射线小角散射法对纳米氧化锆粒度分布的研究

采用小角X射线散射法，在普通的X射线衍射仪上实现纳米级氧化锆粒度分布的表征；并按照国标（GB／T13221-2004）的标准，使用SAXS程序计算出纳米氧化锆的粒度分布范围在1-36nm之间。与纳米氧化锆的TEM图像相比较，对比结果表明该方法测得的纳米氧化锆粒度可靠。     

氧化锆超细粉的绿色合成及粉末性能表征

以低温强碱绿色合成法制备的氧化锆为研究对象,借助于X射线荧光光谱,X射线衍射,透射电镜,粒径分析等测试方法对粉末性能进行了表征,研究表明,绿色合成法具有较大的参数可调容量,制备的粉末纯度高,杂质少,没有检测到较难清除的氯离子并对此进行了分析,粉末主晶相为四方／立方相的氧化锆,无单斜相存在,其一次颗粒尺寸约为7nm,二次颗粒分布狭窄约为1μm,粉末团聚体完全破碎时的压力为250MPa,其单斜相和四方／立方相保持平衡共存的临界粒径为12．6nm。     

模板法制备纳米TiO2及其对纤维素纺织品的抗紫外整理

以廉价无机盐为原料，纳米碳黑作为模板，采用模板法制备了小粒径、窄分布的无团聚纳米金红石TiO2粉体，并用激光粒度分析仪、X射线衍射仅、透射电镜（TEM）、紫外分光光度计等手段对纳米TiO2结构性能进行了表征，研究了纳米TiO2粉体对纤维素织物的抗紫外线整理效果，结果表明：采用模板法所制备的TiO2粉体粒度小（17．56nm）、分布均匀、分散稳定性好；平均粒径为30nm左右的纳米TiO2整理后的纤维素织物抗紫外线效果明显提高。模板碳黑在前驱体的制备以及热处理转相过程中发挥了良好的阻团聚作用。     

Co-Mn-Ni-O热敏纳米粉体的制备及其特性

采用液相共沉淀法用草酸作为沉淀剂制备了Co—Mn—Ni—O陶瓷热敏电阻纳米粉体，并采用综合热分析(TG、DTA)、X射线衍射(XRD)和扫描电子显微技术(SEM)对该法制备的粉体和对照粉体进行了综合表征，结果显示用该方法可以制备品粒平均粒径在9nm左右、粉体颗粒形貌呈球形、颗粒粒径在50～100nm范围内、粒度分布范围较窄约Co—Mn—Ni—O三元系NTC热敏纳米粉体粉体，能够满足Co—Mn—Ni—O陶瓷热敏电阻对粉体的要求。     

纳米氧化锆的制备新工艺研究

以ZroCl2·8H2O和H2O2为原料,采用中和沉淀法制备纳米氧化锆,在制备工艺过程中2次(前驱体制备过程和研磨过程)加入分散剂(表面活性剂)来抑制粉体的团聚.探讨了有关因素对制备氧化锆产品的影响,例如前驱体氢氧化锆的煅烧温度对氧化锆晶型的影响,表面活性剂对产品粒径的影响,煅烧时间对ZrO2平均粒径的影响,研磨助剂对ZrO2平均粒径的影响等,研究得到了最佳工艺条件,并在优化实验条件下制备出平均粒径为50nm、粒径分布均匀的球形纳米氧化锆粉末.     

纳米氧化锌的制备及粒度表征

应用有机物包覆,高温烧结的方法成功制得纳米氧化锌粉体;用X射线衍射线线宽法(谢乐公式)、透射电镜图像分析法和X射线小角散射法对制备的纳米氧化锌进行表征。结果表明,该法制得的纳米氧化锌颗粒呈球形,无明显团聚,粒度分布比较均匀,粒度约为50nm。3种表征方法中用X射线衍射线线宽法得到的平均粒径值最小,其它2种测量方法所得到粉末粒度结果基本一致。     

柠檬酸根对纳米Fe3O4制备及其性能的影响

采用化学共沉淀法制备了纳米Fe3O4粉体材料.用溶液吸附法、透射电镜、X射线衍射仪和古埃磁天平法对添加柠檬酸根前后的纳米Fe3O4粉体材料的结构及性能进行了表征和分析.结果表明:添加柠檬酸根制备的纳米Fe3O4粉体材料的比表面积为1.499,晶粒粒径为8nm,磁化率为11.6534,颗粒度小,分散性好,磁性能更高.     

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。     

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...     

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.     

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.     

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.     

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.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.