ZnO压敏陶瓷的一价离子掺杂

本文研究了一价金属离子掺杂对ＺｎＯ压敏陶瓷电性能的影响。根据晶界的Ｓｃｈｏｔｋｙ势垒模型分析计算了ＺｎＯ晶粒表层１５ｎｍ浅范围的正电荷中心浓度ＮＤ对ＺｎＯ压敏陶瓷小电流区非线性特性的影响。结果表明ＮＤ减小，非线性增强，如果掺入ＺｎＯ压敏陶瓷中的一价金属离子进入了ＺｎＯ晶粒体内对正电中心进行补偿，则会使大电流区的非线性变差。     

ZnO压敏陶瓷的晶粒生长和电学性能

研究了不同价态Co、Mn添加物对低压ZnO压敏陶瓷晶粒生长和电学性能的影响,分析了由于不同价态Mn和Co掺杂所产生的缺陷类型,应用晶粒生长的动力学方程：Gⁿ=Dtexp(-E/RT)确定了晶粒生长的动力学指数和激活能．实验结果表明：对于低压ZnO压敏陶瓷,其晶粒生长的动力学指数n＝6,激活能E＝224±17kJ／mol,随着Mn、Co价态的增加,ZnO压敏陶瓷的平均晶粒大小增加,提高烧结温度,ZnO压敏陶瓷的压敏场强E1mA降低,漏电流IL增加,非线性系数α降低．在低压ZnO压敏陶瓷的制备过程中,烧结温度以不超过1250℃为宜．     

不同受主技能杂对TiO2压敏陶瓷性能的影响

本研究通过在ＴｉＯ２压敏陶瓷制备过程中掺杂不同的受主杂质,讨论了采用不同受主掺杂及不同烧结温度对双功能ＴｉＯ２压敏陶瓷性能的影响。实验结果表明,在１３００℃烧结温度下,以Ｂａ或Ｓｒ掺杂的较Ｐｂ掺杂的Ｔｉ－Ｎｂ－Ｂｉ系压敏陶瓷对改善压敏性能更有利,相对而言,Ｂａ对降低压敏电压,Ｓｒ对提高非线性系数更有效。     

氧化锌压敏陶瓷烧结致密化过程的研究

本文研究了氧化锌压敏陶瓷的致密化过程，结果发现只有当烧结温度升高到一定值时，试样中的ＺｎＯ粉粒产生聚集，致密化过程才开始．致密化是瓷体获得稳定电性能的基础．低熔点添加剂Ｂ２Ｏ３可以降低致密化的起始温度，而致密化过程中的等温烧结对ＺｎＯ压敏陶瓷的最大密度几乎没有影响．     

Sol-Gel法制备ZnO压敏陶瓷及其电性

采用溶胶－凝胶（ｓｏｌ－ｇｅｌ）工艺制备ＺｎＯ电压敏陶瓷粉体．探讨其制备的最佳工艺条件：以 Ｚｎ（ＮＯ_３）_２与 ＮａＯＨ为反应前驱物制取胶体, Ｚｎ^２＋浓度控制在 ０．５ｍｏｌ·Ｌ^－１以上, ｐＨ值７．５左右,预烧温度３００℃,陶瓷烧结温度１２００℃;制得的压敏电阻的非线性系数α＝２８;研究了稀土Ｌａ_２Ｏ_３掺杂对该陶瓷电性的影响：低浓度掺杂时,可提高压敏电压,高浓度掺杂时;不呈现压敏特性;对粉体进行了Ｘ射线衍射和透射电镜分析,预烧后得到五元掺杂的ＺｎＯ粉体粒形呈球状,属六方晶系,粒径分布窄,约为４０～８０ｎｍ．     

工艺和添加剂对TiO2功能陶瓷材料性能的影响

研究了工艺和添加剂对ＴｉＯ２功能陶瓷材料性能的影响。发现提高烧结温度和延长保温时间有利于降低材料的压敏电压和使介电常数升高。当烧结温度在１２５℃至１３００℃之间时，可使材料具有较大的非线系数。添加剂中Ｂｉ２Ｏ３的含量增加，也会降低材料的压敏电压。适量的ＭｎＯ２含量则有利于提高其非线性系数。     

烧结温度对TiO2压敏陶瓷非线性和介电性质的影响

基于一次烧结工艺,通过改变烧结温度,制备5种组分相同、(Sr,Bi,Si,Ta)掺杂的TiO2陶瓷试样.借助于伏安特性、介电频率特性、损耗频率特性及非线性系数的测定,研究烧结温度对TiO2基压敏陶瓷压敏和介电性质的影响.结果表明,在1200～1400℃范围内,随着烧结温度的降低,陶瓷的压敏电压降低、介电常数增大,同时非线性系数有所减小.兼顾陶瓷压敏和介电特性,烧结温度选择1350℃为宜.     

ZnO基陶瓷的导电性能研究

以ＺｎＯ为基添加ＭｇＯ和Ａｌ２Ｏ３制得了ＺｎＯ陶瓷。研究了掺杂含量，烧结温度和降温特性等因素对ＺｎＯ基陶瓷的导电性能影响。研究表明，Ａｌ２Ｏ３含量和烧结温度对ＺｎＯ基陶瓷的电阻率具有较大的影响，ＭｇＯ含量和降温速率对电阻温度系数影响尤为明显。     

Sb掺杂对ZnO-V2O5多元系压敏电阻的影响

本文研究了V/Sb预合成粉、SbVO4和Sb2O3等三种不同形式的Sb掺杂对ZnO-V2O5基压敏陶瓷结构和性能的影响.化学计量比不变情况下,上述Sb掺杂方式的改变,使烧结过程中Sb3 离子在陶瓷样品中的浓度上升,促进Zn7Sb2O12型尖晶石相形成,材料晶粒随之细化.同时材料的压敏电压出现大幅上升,而非线性系数和漏电流密度受Sb掺杂形式的变化影响不大.Sb以V/Sb预合成粉进行掺杂可以获得较大尺寸的晶粒,有利于材料在低压方面的应用.     

湿法合成ZnO压敏陶瓷材料烧结缺陷的研究

研究了湿法合成ＺｎＯ压敏陶瓷材料的烧结缺陷,结果表明,随着烧结温度的提高,有两类微空洞型缺陷存在,它们分别由存在于晶粒表面的ＺｎＯ和晶界中的Ｂｉ２Ｏ３分解挥发产中缺陷的存在是造成ＺｎＯ晶粒极向生长的主要原因。同时讨论了烧结缺陷的产生机理及其对压敏特性的影响。     

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.