高质量四脚状ZnO纳米结构的制备及其影响因素

采用汽相传输法制备高质量四脚状ZnO纳米结构(T-ZnO).以ZnO纳米晶为同质催 化剂,在锌源-衬底间添加蒸汽过滤器,研究过滤器和纳米晶对产物组成和形态的影响,以及 T-ZnO的结构特征.实验结果表明,T-ZnO为纤锌矿结构,分布均匀、尺寸一致,由四个柱 状纳米棒和一个球形核心组成.纳米棒直径约为60nm,沿<0001>晶向生长.过滤器的使用可 有效地去除产物中颗粒,而ZnO纳米晶的使用明显降低其尺寸,提高其均匀性.     

T-ZnO晶须增强环氧树脂复合材料的力学行为

研究了以四脚状氧化锌（T-ZnO）晶须为增强剂，环氧树脂复合材料的力学行为。结果表明，由具有三维空间结构的T-ZnO晶须为增强剂所制备的环氧树脂复合材料具有各向同性的力学性能，T-ZnO晶须填加质量分数为6%时，就可使材料的力学性能改善；拉伸强度提高到169%，拉伸功几乎提高了100%，冲击强度提高到300%，抗弯的断裂功提高到158%，而压缩强度略有下降。     

四脚状氧化锌晶须的微波电磁性能

以锌粉为原料,采用碳还原剂控制法制备了四脚状氧化锌晶须。用光学显微镜、扫描电子显微镜及X射线衍射分析方法对产物进行了表征。实验结果表明,该晶须为纯氧化锌,属于六方晶系纤锌矿结构;整个氧化锌晶须基本为四脚状晶须结构。通过热力学分析及试验表明,在1220~1350 K的温度时,可以得到完整的四脚状氧化锌晶体。用波导法对所得晶须进行了磁导率和介电常数的测量。微波电磁性能试验表明,四脚状氧化锌晶须是一种介电损耗材料,具有一定的微波吸收性能。     

T-ZnO_w制备过程中工艺参数的影响

采用常压下直接热蒸发锌粉的方法制备了四针状氧化锌晶须(T-ZnOw)。研究了升温速率及保温温度对晶须产量、结构及形态的影响。利用SEM及XRD对产物进行了表征。实验结果表明前期升温速率为3℃/min时,所制备T-ZnOw形貌最为规整,且产率高达95%。随着前期升温速率的提高,产物是不均匀的四针状氧化锌晶须,晶须尺寸增加。随着保温温度的增加,晶须细化,但晶须结构的完整性及产量都有所下降。     

蓝晶石制备莫来石晶须的研究

为了降低莫来石晶须的合成温度及生产成本,研究了以蓝晶石为主要原料烧结制备莫来石晶须的影响条件,通过烧结实验发现,原料的粒度、升温速率和催化剂添加量对莫来石晶须的制备有较大影响,影响顺序为：原料粒度〉催化剂添加量〉升温速率。晶须的最佳合成条件为：原料粒度为-325-＋400目,混合样（蓝晶石和氧化铝）与A1F3比例为10：4．0,以1150℃作为成核温度,保温lh,以1250℃作为晶化温度,保温4h,烧结过程中的升温速率为5E／rain,莫来石晶须的产率可以达到64％。     

T-ZnO晶须表面改性及在环氧树脂抗静电漆中的应用

研究了T-ZnO晶须对环氧树脂复合材料抗静电性的影响.采用SEM、IR等测试手段,对T-ZnO晶须改性前后的变化进行了表征与分析,结果表明:以无水乙醇为溶剂,表面活性剂聚乙二醇改性的具有半导体性的T-ZnO晶须均匀分散在环氧树脂中,相互搭接形成导电通路,而起抗静电作用,使环氧树脂材料的体积电阻率降低了4～5个数量级.     

自石灰石矿粉中直接提取CaCO3晶须的碳化-分解法研究

提出一种自石灰石矿粉中直接提取CaCO_3晶须的碳化-分解方法。该方法能够以天然石灰石矿粉为原料,通过水溶性碳酸的作用溶解出Ca(HCO_3)_2,进而在升温条件下通过Ca(HCO_3)_2的分解反应得到形貌规整的棱锥状CaCO_3晶须。扫描电镜观测与X射线衍射分析显示,Ca(HCO_3)_2分解温度对CaCO_3晶须微观形貌的影响显著,晶须长度与长径比随分解温度的升高均呈上升趋势,但分解温度超过80℃会导致文石晶相向方解石晶相转化。实验结果表明,80℃、2h条件下,Ca(HCO_3)_2分解产物中文石晶相含量较高,晶须几何形貌更为合理,其平均长度为14.61 μm、长径比为8.10。     

四角状氧化锌晶须表面镍镀层的制备及电磁性能

采用化学镀方法在四角状氧化锌晶须(T-ZnO)表面制备了镍镀层,并对其电磁性能进行了研究.采用XRD,SEM及EDS对化学镀镍后的T-ZnO晶须进行了结构、形貌以及成分表征.结果表明:随着化学镀时间的延长,在T-ZnO晶须表面包覆了一层镍镀层,镀层具有非晶结构,含有少量的磷,约2%(质量分数).使用波导法对化学镀镍前后的T-ZnO晶须进行了电磁参数的测量.结果表明:化学镀后晶须的微波吸收性能明显增加,在频率为11.7GHz处反射率可达-17.5dB左右,而且最大吸收峰的频率随镍析出量的变化而改变,这样有利于实现吸收频带的展宽.     

四针状氧化锌晶须的研究进展

四针状氧化锌晶须是唯一具有三维空间结构的晶须,在复合材料上的应用受到了越来越多的重视.介绍了T-ZnO的制备方法;侧重从晶体结构特征和生长习性方面综述、讨论T-ZnO的生长机理研究,并指出了存在的问题和进一步研究的方向;最后概述了T-ZnO应用方面的研究.     

不同形态低维ZnO晶须的制备及表征

采用热蒸发法制备出高纯度线状、棒状、多脚状的不同形态ZnO晶须材料.研究了氮气流量、反应温度、反应时间(保温时间)等因素对产物规整率、转化率及长径比的影响.利用SEM对产物形态进行表征.结果表明:采用不同条件的热蒸发法可制备出高质量不同形态的ZnO晶须.反应过程中锌蒸压气对产物形态的影响较大.以陈化锌粉为原料,在1000～1100℃保温较短的时间,并始终以0.2m3/h通入高纯氮气,得到棒状晶须;保温时间较长,得到线状晶须.而多脚状ZnO晶须则是在通入高纯氮气时间较短的情况下得到的.     

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.