真空吸气剂吸氢后样品的热解动力学及热重分析

采用热重分析方法,以氮气为载气,对真空吸气剂吸氢后的样品进行了热解实验。含100%PdO的吸气剂吸氢后的热解分为PdO脱氢、Pd脱氢和PdO分解三个区域,对应的温度区间分别为202~284℃,593~780℃和800~900℃。PdO吸氢是物理吸附,Pd吸氢既有物理吸附也有化学吸附。热重分析的升温速率设定为20℃/min。Ag2O分解与样品脱氢存在明显的协同作用,主要体现在593~780℃的热解区间。吸氢后样品的热解动力学采用3个一级反应来描述。在不同的升温速率和PdO含量的情况下,活化能和频率因子之间存在"动力学补偿效应",其反应性能得到了很大的提高。在常压下,随着吸气剂中Ag2O含量的增加,其活化所需的最高温度明显下降。     

活性炭和TiF3共掺杂对NaAlH4放氢-再氢化性能的影响

采用高能球磨法制备了活性炭(AC)和TiF3共掺杂NaAlH4复合储氢材料,研究了TiF3和AC共掺杂NaAlH4后复合材料的吸/放氢性能。结果表明:共掺杂10%(质量分数)AC和3%(摩尔分数)TiF3明显降低了NaAlH4前两步放氢温度,且较单一掺杂而言,共掺杂AC和TiF3更有利于NaAlH4放氢温度的降低;160℃下NaAlH4+TiF3+AC样品在170 min内放氢5.0%(质量分数),完成理论放氢量的93%;4次吸放氢循环后NaAlH4+TiF3+AC依然具有良好的循环稳定性,在160℃、真空下起始放氢以及130℃、9 MPa起始吸氢条件下,NaAlH4可逆储氢量可达4.8%(质量分数)。     

复合改性活性炭的表征及其吸附模拟烟气中SO_2的研究

为了研究单一金属盐和复合金属盐改性活性炭材料对SO_2吸附性能的影响,以活性炭(activated carbon,AC)为载体,通过水热法制备ZnO/AC复合材料、Fe_2O_3/AC复合材料、ZnFe_2O_4/AC复合材料以及空白AC材料。采用场发射扫描电镜(SEM)、X射线能谱仪(EDS)、X射线衍射仪(XRD)、傅立叶变换红外光谱仪(FTIR)、物理吸附仪(BET)及X射线光电子能谱分析仪(XPS)对复合材料结构及化学组分进行表征,并且在常温条件下考察活性炭复合改性前后对模拟烟气中SO_2的吸附性能。结果表明,复合改性后活性炭材料成功负载金属氧化物活性组分,比表面积孔容减小,孔径增大并且对SO_2的去除效率显著提高。通过AC、ZnFe_2O_4以及4种复合材料脱硫效率的比较发现,负载ZnFe_2O_4的活性炭材料的脱硫效率最高,其比表面积和孔容分别为435.9m~2/g、0.37cm~3/g,脱硫性能试验中样品的击穿时间为136.0min,硫容达到168.3mg/g。     

Pd/C纳米催化剂的制备及催化Heck反应研究

以高比表面积椰壳活性炭为载体,柠檬酸钠为还原剂,在100℃条件下对H2PdCl4溶液进行还原负载,制备了直径在3~10nm的Pd/C催化剂。控制柠檬酸钠与H2PdCl4的量,制备了6个不同粒径Pd粒子负载的Pd/C催化剂,制备条件温和。该催化剂能够高效催化Heck反应的进行,反应无需无水无氧条件,无需配体的参与,重复利用次数较多。     

活性炭纤维对贵金属的吸附

活性炭纤维（ACF）具有优越的氧化还原吸附特性，通过创麻基活性炭纤维（水蒸气活化和磷酸化学活化）与硝酸银溶液反应而将银引入纤维中，X射线衍射分析表明ACF上负载的都是纳米银热处理可使它们的畸变减小且在高于150℃时才长大此外，用其它基体的ACF也可还原吸附贵金属离子（Au+、Pt4+、Pd2＋），并得到晶体生长有取向的纳先资金属粒子复合的活性炭纤维     

通过再活化浸渍金属盐的活性炭来发展中孔结构

研究了在椰子壳活性炭上浸渍金属盐（硝酸铁和硫酸铁）后，在二氧化碳气氛中催化活化对中孔结构的影响。发现硝酸铁对活性炭比表面积（-1930m^2／g）的增加和中孔结构（-10nm）的发展更有效。改性活性炭具有发达的中孔结构，显示了更大的维生素B12吸附容量（是改性前的5倍～8倍）和更快的吸附速度。中孔结构的发展基于三个方面的原因：（1）在活化过程中，浸渍在活性炭微孔内的金属盐分解所释放的氧化性气体与微孔碳壁反应，扩大了孔径；（2）在高温下，来自于金属盐的金属氧化物被碳还原，扩大了孔径；（3）在金属铁存在下，碳壁被催化活化，大大提高了活性炭的中孔率。由此提供了一种廉价的从商业活性炭制备中孔活性炭的有效途径。     

新型无氢胺化催化剂PdHx-Pd/C的水合肼还原法制备及形成机制研究

PdH_x是Pd/C催化剂中重要的活性物种, 在常温无氢的条件下不能稳定存在。在常压无氢条件下, 以PdO作前驱体, 用水合肼还原法可制备出PdH_x含量较高, 且能够稳定存在的PdH_x-Pd/C催化剂。通过XRD、XPS和TEM等表征方法研究了PdH_x和Pd颗粒的微观结构、形貌及化学状态; 提出了水合肼还原法生成PdH_x的机理。实验结果表明: PdH_x颗粒的平均粒径为3.9 nm, PdH_x(111)晶面间距比Pd(111)稍大; PdH_x生成于水合肼对PdO的还原过程, 且其晶粒大小与前驱体PdO的粒度大小及结构不完整性密切相关。将该催化剂应用于无氢条件下胺化法合成2, 6-二甲基苯胺的反应中, 其催化性能明显优于普通的Pd/C催化剂。     

负载TiO2活性炭电极材料的制备工艺

采用溶胶-凝胶法对活性炭进行载钛改性,制备TiO2/AC电极材料。通过正交实验考察改性过程中无水乙醇(C2H5OH)、去离子水(H2O)、冰乙酸(CH3COOH)、盐酸(HCl)以及活性炭(AC)这五种成分的最佳加入量。利用比表面积及孔径分析仪(BET)、电化学工作站分别对材料的比表面积和电极比电容进行表征。结果表明,材料组成的最佳加入量为无水乙醇30mL、冰乙酸2mL、盐酸0.3mL、去离子水4.5mL、活性炭2g。各因素对电极的电化学性能影响大小依次为:AC量>CH3COOH量>C2H5OH量>去离子H2O量>HCl量。载钛后活性炭比表面积从680.5m2/g降为523.35m2/g,降低23.1%;比电容从116F/g升到135F/g,升高16.4%。活性炭材料负载TiO2处理后,可以加速电极双电子层的形成,提高电极比电容量。     

金属Mn/活性炭电极材料电化学性能的研究

选用不同孔结构的活性炭采用浸渍法负载Mn金属离子,考察活性炭在负载前后的比电容变化情况。研究表明,金属Mn具有比较明显的准电容效应,其中负载金属Mn的中孔活性炭和微孔活性炭的比电容分别增加63．17％和19．69％,中孔活性炭负载金属Mn时,比电容随负载量的增加而上升;微孔活性炭负载5％时比电容最大为340．16F／g。     

低负载量Pd/CeO2/γ-Al2O3催化剂用于低温催化氧化VOCs

采用直接吸附法制备了Pd负载量为0.03% (质量分数)的Pd/γ-Al₂O₃和Pd/CeO₂/γ-Al₂O₃催化剂, 并用于评价VOCs的催化氧化性能。通过X射线衍射(XRD)、N₂吸附-脱附(BET)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、氢气程序升温还原(H₂-TPR)等对催化剂的结构和表面性能进行了表征。结果表明, 在VOCs体积分数为0.1%, 空速(GHSV)为18000 mL/(g·h)条件下, Pd/CeO₂/γ-Al₂O₃催化剂上甲苯、丙酮和乙酸乙酯实现98%转化率的温度分别为205、220和275 ℃, 比Pd/γ-Al₂O₃分别降低了15、15和20 ℃, 而且即使在较高的气体空速下, Pd/CeO₂/ γ-Al₂O₃催化剂仍能展现出优异的催化氧化性能, 且具有很好的稳定性和选择性。氧化铈的加入对材料的物理化学性质和催化活性有一定的影响, 其中Pd/CeO₂/γ-Al₂O₃含有Ce ³⁺和高含量的PdO, 活性物种主要以PdO形式均匀地分散在载体γ-Al₂O₃表面。另外, PdO与非化学计量的CeO₂之间的金属-载体相互作用增强了Pd/CeO₂/γ-Al₂O₃催化氧化性能。     

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 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.     

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.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.