w^6＋掺杂TiO2纳米材料化学吸附与氧敏特性研究

以TiCl3为钛源，采用溶胶-凝胶法制备W^6＋掺杂TiO2纳米粉体，经400℃低温烧结1h，即可得到以金红石相为主相的TiO2基氧敏材料。采用XRD、BET、TPD等手段对其进行表征、分析，结果表明W^6＋掺杂有利于形成以金红石相为主相的晶体结构，使样品的晶粒尺寸减小、比表面积增加，使氧敏特性提高，其中12％（摩尔分数）W^6＋／TiO2的氧气化学吸附量最大，敏感层表面对氧气的活性最高；在低工作条件（115℃）及1×10^-4氧气下，W^6＋掺杂TiO2的厚膜型气敏元件氧敏特性得以明显提高，且掺杂12％（摩尔分数）W^6＋灵敏度最佳（S=16．5）。     

S／TiO2纳米氧敏材料的结构与吸脱附特性

以TiCl3为钛源,采用溶胶一凝胶法,在500℃(1h)烧结获得非金属离子(硫)掺杂TiO2的纳米粉体,利用XRD,FT-IR,UV-vis,ESEM,Zeta电位,XRF,TPD等表征S/TiO2结构特性.结果表明,硫掺杂有利于其向金红石相转变,低掺杂浓度(2at%)时,硫主要以S4 形式存在,当掺杂量为25at%时,部分掺杂硫以S2-形式替代O2-,由于两者间的电负性差异,导致表面上Ti3 、Ti4 周围的电子云密度增加,从而提高样品对氧气的吸附活性,使其表面的富余电子向吸附氧转移,提高了氧敏特性.S/TiO2敏感体表面的吸附氧以氧分子形式脱附(≤550℃),而在高温(≥600℃)下主要以SO2形式脱附.     

硅基板上Fe掺杂TiO2氧敏薄膜的制备、结构与性能研究

采用溶胶-凝胶法,以Ti(OC4H9)4为前驱体,用提拉法在硅基板上制备了掺Fe的TiO2氧敏薄膜,对薄膜物相结构进行了X射线衍射(XRD)测定,利用扫描电镜(SEM)对薄膜微结构进行了观察.结果表明在硅基板上生长的TiO2薄膜中锐钛矿相为均匀小晶粒分布结构,金红石相以大尺度团聚结构形貌出现.Fe离子的掺杂对硅基板上制备的TiO2薄膜中金红石相的形成有很大的影响.Fe的掺入降低了金红石相的形成温度约100℃,Fe掺量在6mol%时,形成金红石相的量达到最大,即析晶能力最强.薄膜中形成晶相的晶格常数在＜6mol%的低Fe范围内,随较小的Fe离子取代较大的Ti离子,锐钛矿相和金红石相的晶格常数都随之减小;在＞6mol%的高Fe掺量范围内,随Fe掺量的增加,体系缺陷过量增加,晶格结构畸变严重,伴随着畸变能的释放,金红石相的晶格常数c轴逐渐增长,a轴略有下降(或基本不变).TiO2氧敏薄膜的氧敏性能受金红石相含量和氧空位浓度控制.当Fe离子掺杂浓度为6mol%时,金红石相及相应氧空位达到最大值,TiO2氧敏薄膜的氧敏性能也达到最大值,比刚形成金红石相的薄膜的氧敏性能增加近19倍.     

超细Mo-30Cu复合粉末的烧结行为

采用溶胶-喷雾干燥-煅烧-氧还原方法制备了晶粒尺寸为17-30 nm的超细Mo-30Cu复合粉末,在制备过程中经历了一系列的相转变,由喷雾干燥复合盐前驱体Cu7.6O8(NO3)+(NH4)2(Mo4O13)+(NH4)6(Mo7O24)(H2O)4+Cu4Mo5O17+CuMoO4在450℃煅烧后转变为CuMoO4+MoO3复合氧化物,在300℃低温还原转变为MoO2+Cu2O+Cu三相,再在700℃高温还原完全转变为Mo+Cu两相复合粉末.该粉末在1050-1200℃烧结时从亚稳态Mo(Cu)固溶体逐渐转变为Mo和Cu相,在1050℃烧结后得到致密度为99.7%的细晶合金.合金的最大抗拉强度可达755 MPa,最大延伸率可达15.8%.     

稀土掺杂TiO2在1064nm激光激发下的上转换发光

为研究TiO2材料的上转换发光特性,采用溶胶-凝胶与共沉淀法制备了La3+、Yb3+和Er3+稀土离子掺杂的TiO2粉末.利用SEM和XRD表征发光材料的结构,探讨了试样在1064nm激发光源常温激发作用下,稀土氧化物的掺杂比例、煅烧温度对上转换发光特性的影响.实验表明,1064nm激光常温激发TiO2基掺杂稀土La2O3、Yb2O3、Er2O3的最佳比例为39∶ 10∶1,经1300℃煅烧可制备出明亮绿色发光的上转换材料.     

TiO_2基气敏元件工作温度影响机理

对TiO2基气敏材料的能带结构及测试气体分子轨道能量进行理论计算,结合实验,对TiO2-SnO2复合材料气敏元件工作温度的影响机理进行理论研究.结果表明:掺杂使TiO2能带带隙中产生掺杂能带,导带产生负移,有利于电子热激发.对比未掺杂TiO2气敏元件,在工作温度为260℃时,掺杂使TiO2元件电阻值由44.5Mù下降到22.5Mù.气体分子LUMO能级降低,有利于降低气敏反应的活化能,从而降低气敏元件的工作温度及提高灵敏度.     

（Sr^2＋，Bia^3＋，Si^4＋，Ta^5＋）掺杂的TiO2压敏陶瓷中Ta^5＋的研究

研究Ta2O5对(Sr,Bi,Si,Ta)掺杂的TiO2基压敏陶瓷压敏特性及电容特性的影响,发现按配方TiO2+0.3%(SrCO3+Bi2O3+SiO2)+0.1%Ta2O5配制的样品具有最低压敏电压(E10mA=1.2V·mm-1)、最大相对介电常数(εra=2.002×105)及较小非线性系数(a=2.6).考虑到材料的低压敏电压和大介电常数的要求,Ta2 O5最佳掺杂量在0.085mol%与0.1mol%之间.     

金属离子掺杂TiO2的光催化性能研究

用醇盐水解法制备了Ce4+、Ag+、Fe3+、Fe2+、Sn4+、Zn2+、Mo6+等金属离子掺杂的TiO2复合微粒.以罗丹明6G降解为目标反应,研究了所制备的复合微粒光催化活性与选择性.并用IR、XRD、TEM及BET等技术,对TiO2复合微粒进行了表征.结果显示在TiO2内掺入Ce4+、Ag+、Sn4+,可使纳米TiO2的光催化活性增强,而Fe3+、Fe2+、Zn2+、Mo6+等金属离子掺杂的二氧化钛复合微粒的催化活性呈下降趋势.     

Fe3+-SiO2掺杂纳米TiO2的制备及其光催化降解甲基橙的研究

以三嵌段非离子表面活性剂P123为模板,采用水热法制备了Fe3+-SiPO2掺杂纳米TiO2,通过X射线衍射(XRD)、红外光谱(FT-IR)、紫外-可见吸收光谱(UV-Vis)等手段考察了Fe3+-SiO2掺杂纳米TiO2的结构与光学特性.实验结果表明:Fe3+、SiO2掺杂进入TiO2的晶格,可获得高纯度锐钛矿相纳米TiO2.Fe3+和SiO2的加入有助于抑制金红石相的形成和晶粒长大,提高了TiO2的热稳定性.Fe3+-SiO2掺杂将TiO2的光响应范围拓宽至可见光区,提高了纳米TiO2的光催化性能.与纯纳米TiO2相比,Fe3+-SiO2掺杂纳米TiO2光催化降解甲基橙的性能显著提高.     

WO3∶Mo纳米晶的制备及其光学氢敏特性研究

用水热法制备了不同掺杂浓度的WO3∶Mo纳米晶粒,研究了WO3∶Mo的微结构和形貌,分析了Mo的掺杂浓度对微结构的影响,并研究了该材料对氢气的光学敏感特性。结果表明,所有样品均呈现六方相结构,掺杂浓度为2%(原子分数)样品的(200)晶面的衍射峰最强;随着掺杂量的增加,样品的带隙减小;当工作温度为200℃时,掺杂浓度为2%(原子分数)的样品对浓度5.0×10-4的氢气表现出良好的光学氢敏特性。     

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.……     

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.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

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.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.