ZnO/ZnSnO3纳米复合物的制备及其HCHO气敏性研究

采用水热法在不同温度下制得两种氧化锌/偏锡酸锌(ZnO/ZnSnO3)复合氧化物。通过XRD、SEM、比表面积及孔隙度分析仪分别对复合氧化物的晶体结构、微观形貌、比表面积等进行表征,结果表明,160℃水热条件制得了氧化锌/片状偏锡酸锌纳米复合氧化物,而180℃条件下制得了颗粒状ZnO/ZnSnO3纳米复合物,平均粒径16nm。采用传统旁热式结构对上述两复合氧化物进行HCHO敏感性能研究,结果发现两种复合氧化物对甲醛都表现出良好的气敏特性,其中氧化锌/片状偏锡酸锌复合氧化物的甲醛气敏特性尤为突出,工作温度110℃时对0.5×10-6甲醛有很好的响应。     

Zn_2SnO_4多面体的水热合成及气敏性能研究

采用水热法合成了锡酸锌(Zn_2SnO_4)多面体,通过X射线衍射和扫描电子显微镜对其物相和形貌进行了表征,并测试了基于Zn_2SnO_4多面体所制得的气敏元件的气敏性能。研究结果表明,气敏元件对乙醇具有良好的选择性,在300℃的最佳工作温度下,气敏元件对浓度为1000mg/L的乙醇气体的灵敏度达到19.2。     

偏锡酸锌气敏材料敏感机理的研究

偏锡酸锌是一种重要气敏材料,通过对其材料及元件进行的电导率与温度的关系,电阻与真空度的关系,Ｘ光电子能谱等的测试分析,了偏锡酸锌气敏材料的敏感机理。     

苯甲酸对化学沉淀法制备氧化锌纳米粉体的影响

利用化学沉淀法,对前驱体沉淀物在采用苯甲酸水热改性和未改性2种条件下分别制备氧化锌粉体,通过X射线衍射、扫描电镜等表征手段考察苯甲酸水热改性对氧化锌颗粒形貌的影响,并对苯甲酸水热改性片状氧化锌纳米颗粒的形成机理进行探讨。结果表明:在未改性条件下制得的氧化锌为颗粒状,平均粒径为300~400 nm;采用苯甲酸对前躯体沉淀物进行水热改性可得片状氧化锌纳米颗粒,片层厚度为30~60 nm。     

纳米SnO_2/SiO_2复合材料的制备及其对H_2气敏性研究

采用锡粒氧化法合成纳米二氧化锡(SnO2),并以KH-550为改性剂,对纳米二氧化锡进行表面化学修饰,制得SnO2/SiO2复合材料,研究了不同条件下制得的SnO2/SiO2复合材料对H2的气敏性能。实验结果表明较佳的SnO2/SiO2复合材料制备工艺条件为:室温条件下,改性剂与纳米二氧化锡质量百分比为9%,在甲苯溶剂中反应3h。制备的SnO2/SiO2复合材料对1000ppm H2的气体灵敏度为37.506。     

纳米三氧化钨的水热合成及其性能研究

以钨酸为前驱体,利用水热合成法制备出纳米三氧化钨粉体,通过透射电子显微镜(TEM)对合成产物进行了结构表征,前驱体钨酸的制备温度对纳米三氧化钨的形貌有较大影响,钨酸的制备温度为60℃时合成出具有纳米尺寸的菱形结构。比较不同条件下制备的纳米三氧化钨的气敏性能,随着乙醇和丙酮浓度的升高,它们的输出电压均呈现出上升的趋势,80℃下制备的钨酸水热合成的纳米三氧化钨不具有稳定的电压,具有菱形结构的纳米三氧化钨材料具备优异的气敏性能。     

纺丝法制备多级SnO2纳米纤维及其气敏特性研究

为了提高SnO2的气敏性能,以PVP为有机溶剂,采用静电纺丝法制备了多级结构的SnO2纳米纤维,利用XRD,SEM和TEM等技术对材料的结构、形貌进行了表征,并制备了SnO2旁热式气敏元件.采用静态气体测试系统对SnO2元件进行了气敏测试.在工作温度300℃时,对0.5~50 ppm甲醛进行了气敏测试.测试结果表明:SnO2气敏元件对甲醛气体具有优异的响应灵敏度,快速的响应及响应恢复特性、较好的选择性.采用静电纺丝制备的多级结构SnO2纳米纤维对甲醛表现出良好的气敏特性.     

微波水热合成γ-AlOOH和γ-Al2O3纳米片

以九水合硝酸铝和尿素为原料,聚乙烯吡咯烷酮为表面活性剂,在180℃微波水热条件下反应30min,制备了γ-AlOOH片状结构产物。此前驱物经600℃热分解2h,得到γ-Al2O3纳米片。采用SEM、TEM、SAED和XRD等方法对样品进行表征,并测试了γ-Al2O3纳米片对刚果红染料的吸附性能。实验结果表明,采用微波水热法可以得到长度约为1μm,厚度为30nm的γ-AlOOH纳米片,该产物经煅烧处理后可以得到微观形貌保持不变的γ-Al2O3纳米片,且片状结构表面存在介孔结构。γ-Al2O3纳米片状结构表现出对废水中刚果红污染物的强吸附性能。     

Cu2+掺杂ZnO纳米棒的制备及气敏性能研究

通过溶剂热法(无水乙醇)制备了Cu2+(0～6mol%)掺杂ZnO纳米棒粉体,采用X射线衍射仪和扫描电镜对掺杂ZnO纳米粉体的晶体结构和微观形貌进行了表征.研究了Cu2+掺杂比例、溶剂热反应温度及时间对材料气敏性能的影响;考察ZnO(120℃,10h)和3mol%Cu2+掺杂ZnO(120℃,10h)粉体对应元件对甲醛、乙酸、甲苯、乙醇、丙酮、三甲胺等六种气体的气敏性能.结果表明:通过溶剂热法制备的ZnO粉体为纳米棒状结构,棒长度和直径随Cu2+掺杂比例不同发生变化;3mol%Cu2+掺杂ZnO(120℃,10h)样品对应元件对低浓度乙醇有很好的选择性,在395℃工作温度下对1×10–3乙醇的灵敏度为380.5,响应和脱附时间分别为5 s和40 s,对1×10–6乙醇的灵敏度可达4.2.     

纳米NdFeO_3和GdFeO_3的制备及其气敏性能

以Nd2O3或Gd2O3和FeCl3·6H2O为主要原料,以NaCl为助熔剂,利用固相反应法制备了NdFeO3和GdFeO3纳米晶。用XRD、TEM分别对产品进行了物相和形貌表征,将获得的纯相样品制成烧结型气敏元件,研究了其对丙酮、甲醛、乙醛、乙醇和乙酸的敏感性能。结果表明:纯相纳米NdFeO3和GdFeO3的制备条件分别为900℃煅烧2h与1000℃煅烧4h;其气敏性能测试结果显示,基于NdFeO3材料的元件对被试气体在310℃时均有较强的响应,其中对1000ppm(10-6)酒精灵敏度高达187,基于GdFeO3材料的元件对1000ppm的丙酮、乙酸和甲醛最佳工作温度为260℃,其中对1000ppm甲醛灵敏度达67.1,且该元件在315℃时对1000ppm酒精和乙醛有较强的响应,其中对酒精的灵敏度达90.8。     

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.……     

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.     

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.     

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.     

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.     

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