Cr2O3对(Co,Ta)掺杂的SnO2压敏电阻电学特性的影响

研究了Cr对(Co,Ta)掺杂的SnO2压敏材料电学性质的影响.当Cr2O3的含量从0增加到0.15mol%时,(Co,Ta)掺杂SnO2压敏电阻的击穿电压从206V/mm增加到493V/mm;1kHz时的相对介电常数从1968猛降至498;晶界势垒高度分析表明,SnO2晶粒尺寸的迅速减小是样品击穿电压增高、相对介电常数急剧降低和电阻率迅速增大的主要原因.对Cr含量增加引起SnO2晶粒减小的原因进行了解释.掺杂0.15mol% Cr2O3的SnO2压敏电阻非线性系数为24,击穿电压达498V/mm,在高压保护领域有很好的应用前景.     

CuO掺杂对 SnO2压敏材料性能的影响

研究了掺杂 CuO对 SnO2· Ni2O3· Ta2O5压敏材料电学性能的影响.实验发现,随着 CuO的 掺杂量从 0.50mol%增加到 1.50mol%,材料的压敏电场强度从 132V/mm升高到 234V/mm,相对 介电常数从 4663减小到 2701.电场强度变化的原因是 CuO掺杂引起的晶粒尺寸变化,随掺杂量 增加晶粒尺寸从 18.8μ m减小到 13.3μ m.未固溶于 SnO2晶格而偏析在晶界上的 CuO阻碍了相 邻 SnO2晶粒的融合 ,这导致了晶粒尺寸的减小.为了解释 SnO2· Ni2O3· Ta2O5· CuO电学非线性 性质的起源,本研究对前人的晶界缺陷势垒模型进行了修正.对该压敏材料进行了等效电路分析, 实验测量与等效电路分析结果相符.     

Na对SnO2-CoO-Nb2O5系压敏材料电学性能的影响

研究了Na对新型(Co，Nb)掺杂SnO2压敏材料微观结构和电学性质的影响。当Na2CO3的含量从0增加到1.2mol％时，(Co，Nb)掺杂SnO2压敏电阻的击穿电压从275V／mm增到919V／mm。样品的微观结构分析发现，当Na2CO3的含量从0增加到1．2mol％时，SnO2的晶粒尺寸明显的变小。晶界势垒高度测量揭示，SnO2的晶粒尺寸的迅速减小是压敏电压急剧增高的原因。对Na含量增加引起SnO2晶粒减小的根源进行了解释。掺杂0．4mol％Na2CO3的SnO2压敏电阻非线性系数达28．4．击穿电压为755V／mm，掺杂1.2mol％Na2CO3的SnO2压敏电阻非线性系数为11．5，击穿电压高达919V／mm，它们在中高压保护领域会有很好的应用前景。本文并指出替代Sn的受主离子Na不应处于SnO2晶格中，而是处于间界上，从而进一步解释了压敏电压急剧增高的原因。     

Ag掺杂对新型SnO2压敏材料的电学性质的影响

烧渗银电极对压敏电阻的性能是有很大影响的.为了弄清Ag对(Co、Nb)掺杂的新型SnO2压敏材料电学性质的影响,做了组分为SnO2+1.50%CoCl2*6H2O+0.10%Nb2O5+x%Ag2O(x=0.00、0.02、0.50和1.00)的系统实验.当AgO的含量从0.00增加到1mol%时,(Co, Nb)掺杂SnO2压敏电阻的击穿电压从349V/mm增大到429V/mm,1kHz时的相对介电常数从2240减小到1560.晶界势垒高度测量揭示,SnO2的晶粒尺寸的迅速减小是击穿电压急剧增高和介电常数迅速减小的主要原因.对Ag掺杂量增加引起SnO2晶粒减小的根源进行了解释.     

Pb掺杂SnO2压敏电阻的晶粒尺寸效应

研究了Pb3O4对(Co，Nb)掺杂SnO2压敏材料电学性质的影响，当Pb3O4的含量从0．00增加到0．75％(摩尔分数，下同)时，(Co，Nb)掺杂SnO2压敏电阻的击穿电压从426V／mm迅速减小到160V／mm，40Hz时的相对介电常数从1240迅速增加到2760，这说明Pb3O4是调控SnO2压敏材料击穿电压和介电常数的敏感添加剂，晶界势垒高度测量表明，在实验范围内Pb的含量对势垒高度的影响很小，随着Pb含量的增加，SnO2的晶粒尺寸的迅速长大是击穿电压迅速减小和介电常数迅速增大的主要原因，对样品的复阻抗进行了测量，发现未掺杂Pb的样品具有最低的晶界电阻，而掺杂0．50％Pb3O4的样品具有最高的晶界电阻，提出了一个修正的缺陷势垒模型，指出了替代Sn的受主不应当处于晶界上，而应处于耗尽层的Sn的晶格位置。     

V~(5+)-Sr~(2+)共掺杂对TiO_2基压敏陶瓷性能的影响

研究了V~(5+)-Sr~(2+)共掺杂对TiO_2基压敏陶瓷电学性能的影响。采用固相烧结方法制备V~(5+)-Sr~(2+)共掺杂TiO_2样品。利用XRD衍射仪检测物相和SEM测定显微结构。用压敏电阻直流参数仪测定V~(5+)-Sr~(2+)共掺杂TiO_2样品在不同烧结温度和掺杂量下的电学性能。结果表明:掺杂0.35mol%的V_2O_5,XRD衍射仪没有检测到第二相的产生。随着SrCO_3掺杂量以及烧结温度的增加,样品压敏电压和非线性系数都有不同的变化趋势。当烧结温度为1 300℃、Sr~(2+)掺杂量为0.5mol%时,样品的各项电学性能最优:V~(5+)-Sr~(2+)共掺杂TiO_2样品压敏电压达到16.3V/mm,非线性系数α达到5.6。     

B_2O_3掺杂氧化锌压敏电阻烧结工艺的微观结构和电气特性

研究了在不同烧结温度下制备的直流ZnO压敏陶瓷的微观结构和电气特性。通过扫描电子显微镜,电流-电压的伏安特性,电容-电压和从小电流到大电流范围的X射线衍射图测量不同烧结温度下样品的电气参数和微观结构。实验结果表明在1150℃下烧结的样品晶粒尺寸比较均匀,非线性系数和泄漏电流分别为66和0.96μA/cm~2,电压梯度为381 V/mm,直流氧化锌压敏电阻的综合性能达到最优。随着烧结温度的升高,ZnO晶粒尺寸(d)会变大,导致单位长度内晶界数量减少使氧化锌压敏电阻的电压梯度减少。晶粒的尺寸的增加可以阻断三角区的互联互通,使泄漏电流减小。当烧结温度高于1 150℃时,会造成Bi_2O_3的挥发使非线性系数降低。获得电压梯度为381 V/mm的直流氧化锌压敏电阻有利于优化超高压避雷器结构、电阻柱上的电位分布更加均匀。综上所述,制备B_2O_3掺杂的氧化锌压敏电阻配方最佳的烧结温度为1 150℃。     

Sr掺杂对WO3-CeO2低压压敏陶瓷电性能的影响

制备了不同掺量SrCO3的WO3-CeO2系列低压压敏陶瓷．研究结果表明：随着SrCO3掺量的增加，WO3，晶粒尺寸逐渐减小，样品的压敏电压明显增大，非线性系数α先增大后减小．在SrCO3掺量为0．5％（摩尔分数）时，样品表现出较好的压敏性能，其压敏电压可低至9．1V／mm，非线性系数高至3.3．探讨了Sr元素掺杂的作用机理．     

稀土氧化物Pr2O3掺杂对高压ZnO压敏电阻性能的影响

采用低温固相化学反应法制备了Pr2O3掺杂的ZnO纳米复合粉体,并用此粉体在不同烧结温度下制备了高压ZnO压敏电阻.采用X射线衍射、比表面测试、透射电镜、扫描电镜等手段对制备的ZnO纳米复合粉体及高压ZnO压敏电阻进行了表征,并与未掺杂ZnO压敏电阻进行了对比研究,探讨了稀土氧化物Pr2O3掺杂对高压ZnO压敏电阻电性能的影响机制.结果表明:较低的烧结温度(1030～1130℃)时,掺杂的稀土氧化物Pr2O3偏析于ZnO晶界中,有活化晶界、促使晶粒生长的作用;同时,Pr2O3掺杂导致1080℃烧结的ZnO压敏陶瓷体中晶体相互交织形成晶界织构,比未掺杂的更均匀和致密,这有助于高压ZnO压敏电阻晶界性能的改善,从而提高其综合电性能.当烧结温度为1080℃时,Pr2O3掺杂的高压ZnO压敏电阻的综合电性能最佳:电位梯度为864.39 V/mm,非线性系数为28.75,漏电流为35 μA.     

Zn_2SnO_4掺杂对SrTiO_3陶瓷烧结温度和储能性能的影响

采用固相反应法制备了SrTiO_3+xmol%Zn_2SnO_4(x=1,2,5,10)陶瓷,研究了Zn_2SnO_4掺杂对SrTiO_3陶瓷烧结温度和储能性能的影响。结果表明,Zn_2SnO_4掺杂可将SrTiO_3陶瓷的最佳烧结温度从1 400℃降低至1 200℃。随着掺杂量的增加,SrTiO_3陶瓷的室温介电常数逐渐减小,击穿电场和储能密度呈现先增大而后减小的趋势。当Zn_2SnO_4掺杂量为2 mol%时,样品具有最大的击穿电场250 kV/cm和最高的储能密度1.06 J/cm~3。相较于未经掺杂的SrTiO_3陶瓷,储能密度提高了1.8倍。深入研究表明,由于烧结温度降低,SrTiO_3陶瓷的平均晶粒尺寸从5.5μm降低至0.8μm左右,从而增加了晶界的相对含量,提高了材料的绝缘性能,进而增强了SrTiO_3陶瓷的击穿电场,最终导致了SrTiO_3陶瓷储能密度的提高。     

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.