聚合物包覆热分解法制备纳米氧化锌的工艺研究

采用聚合物包覆热分解法化学工艺制备了纳米氧化锌，对其工艺进行系统的比较研究，对所得粉体进行XRD与SEM表征。发现利用该工艺所得粉体为六方晶系纤锌矿结构（空间群为P63mc）的纳米氧化锌。该方法制备的氧化锌衍射峰尖锐，表明此种方法合成的氧化锌结晶程度高。所得的氧化锌粉体XRD图谱中没有杂质衍射峰，说明产物纯度都很高。产品SEM表征结果显示了此工艺产物在形貌方面的高度一致性—为菊花状氧化锌纳米杆团簇，文中对产物形貌形成的原因做了详细的探讨。     

预处理基底上择优取向的ZnO纳米柱的制备

在预处理基底上，采用化学溶液沉积法在低温下制备氧化锌纳米柱薄膜。通过X射线衍射（XRD）和扫描电镜（SEM）表征了氧化锌纳米柱的形貌和晶体结构。研究表明，控制制备过程中的工艺条件：氨水含量、烧结温度、沉积温度、ZnCl2浓度，可以达到优化氧化锌纳米柱的形貌和晶形取向的目的，最后得到单分散性、规整、高度取向的氧化锌纳米柱。并利用晶体生长理论和预处理基底的形貌表征等对反应机理、晶体取向进行讨论。     

预处理基底上择优取向的ZnO纳米柱的制备

在预处理基底上,采用化学溶液沉积法在低温下制备氧化锌纳米柱薄膜.通过X射线衍射(XRD)和扫描电镜(SEM)表征了氧化锌纳米柱的形貌和晶体结构.研究表明,控制制备过程中的工艺条件:氨水含量、烧结温度、沉积温度、ZnCl2浓度,可以达到优化氧化锌纳米柱的形貌和晶形取向的目的,最后得到单分散性、规整、高度取向的氧化锌纳米柱.并利用晶体生长理论和预处理基底的形貌表征等对反应机理、晶体取向进行讨论.     

不同衬底生长氧化锌纳米棒阵列及其场发射性能的研究

采用低温水热法在五种不同基底上制备得到了氧化锌纳米棒阵列，通过SEM、TEM、XRD、EDS和XPS表征研究了所得产物的微观形貌和元素组成，并对不同基底生长的氧化锌纳米棒阵列进行了场发射性能和附着力测试。结果表明：硅片、导电玻璃、镍片、不锈钢和镍钛合金上生长的氧化锌纳米棒样品的开启电场依次升高；由于氧化锌纳米棒与硅基底之间具有更好的附着性能，硅片基底制备的氧化锌纳米棒场发射性能最好，并显示出最好的发射稳定性，在电流密度0.5mA/cm²下持续工作15h时，其电流波动小于10%。     

氨水对纳米氧化锌的影响

以六水硝酸锌为锌源,氨水为沉淀剂,聚乙二醇为分散剂,直接制备了纳米氧化锌.利用X射线衍射(XRD)和透射电子显微镜(TEM)对纳米氧化锌的晶体结构、尺寸和形貌进行了表征.结果表明,在氨水的质量分数为19％,温度为60℃的条件下合成的纳米氧化锌属于六方纤维矿单晶结构,呈棒状形貌,直径约为72nm,长径比约为8.5.讨论了氨水作用下纳米氧化锌的形成机理以及氨水浓度对产物形态和纳米氧化锌收率的影响.     

表面活性剂对纳米氧化锌形貌和发光性能的影响

以二水合乙酸锌和氢氧化钠为原料,分别以表面活性剂十六烷基三甲基溴化铵(CTAB)和聚乙烯吡咯烷酮(PVP)为结构导向剂,采用简单的水热法制备了不同形貌的纳米氧化锌。研究了两种表面活性剂对纳米氧化锌形貌和光致发光性能的影响,并探讨了表面活性剂的作用机理。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和室温光致发光光谱(PL)等测试方法对样品的结构、形貌和发光性能进行了表征。结果表明:添加了表面活性剂后,样品形貌和尺寸都更加均匀,紫外发射峰强度相对增加。     

ZnO/Al2O3复合纳米颗粒的制备与表征

以硫酸锌和氢氧化钠为原料,采用直接沉淀法制备了纳米氧化锌,并用硫酸铝水解生成的三氧化铝对钠米氧化锌进行了表面改性,并采用IR、TEM、SEM、XRD等手段对改性前后的粉体进行表征研究.TEM和SEM分析结果表明,改性后粉体颗粒的粒径小、团聚现象减轻.此外,进行了粉体的光催化降解甲基橙的实验研究.实验结果表明,改性后ZnO粉体的光催化活性明显下降,这进一步证明了纳米氧化锌颗粒表面存在三氧化二铝的包覆层.     

ZnO/Al2O3复合纳米颗粒的制备与表征

以硫酸锌和氢氧化钠为原料,采用直接沉淀法制备了纳米氧化锌,并用硫酸铝水解生成的三氧化铝对钠米氧化锌进行了表面改性,并采用IR、TEM、SEM、XRD等手段对改性前后的粉体进行表征研究.TEM和SEM分析结果表明,改性后粉体颗粒的粒径小、团聚现象减轻.此外,进行了粉体的光催化降解甲基橙的实验研究.实验结果表明,改性后ZnO粉体的光催化活性明显下降,这进一步证明了纳米氧化锌颗粒表面存在三氧化二铝的包覆层.     

纳米铝酸锂粉体制备的正交实验研究

采用柠檬酸盐水解法制备出纳米LiAlO2粉体，并通过正交实验法来优化制备纳米LiAlO2的工艺条件，据此获得了制备纳米LiAlO2粉体的最优工艺为：煅烧温度690℃，柠檬酸与金属盐的比例为1：1，保温时间为2h，Li^＋的浓度为0.5mol／L。通过X射线衍射、扫描电镜等分析手段对制得的LiA102粉体颗粒的物相、晶粒尺寸和微观表面形貌进行表征。由SEM图谱可知，在最佳条件下制得的LiA102粉体颗粒尺寸在100nm左右。     

以汞为反应介质制备氧化锌纳米空心球

以汞为反应介质, 表面活性剂胶束为模板, 通过锌的氧化反应制备了氧化锌空心球. 采用SEM、EDX、TG、DTA、XRD、IR等测试手段对产物的形貌和结构进行了表征, 并考察了表面活性剂对产物生长的影响. 研究表明, 氧化锌空心球为无定型结构, 壁厚为纳米尺度, 由氧化锌纳米粒子组装而成, 煅烧后转变为六方纤锌矿结构. 加入适量PEG或CTAB, 能制备出氧化锌空心球; 不加入表面活性剂、加入过量PEG或SDBS, 则不能制备出氧化锌空心球.     

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.