以乙酸酐为反应介质制备低硫可膨胀石墨

本文报道了一种制造低硫可膨胀石墨的新方法，即于２５℃，在含有少量硫酸的乙酐溶液中制备低硫可膨胀石墨。其最佳参数是：乙酐与石墨的重量比为１：１；高锰酸钾与石墨的重量比为６％；硫酸和石墨的重量比为１３％；反应时间２ｈ；反应温度２５℃，所制得的可膨胀石墨含硫量为０．９１％，膨胀容积为每克可膨胀石墨２４０ｍＬ，比传统方法制得可膨胀石墨含硫量降低了三倍左右。迄今为止，未见文献做过类似报道。     

混酸法制备低硫可膨胀石墨

用硫酸（９８％）、硝酸（６５％）和草酸的混合液与天然鳞片石墨反 制备低硫可膨石墨，最佳反应条件是：石墨、硫酸（８％）、硝酸（６５％）、草的重量比为１：２．３：１．７：０．０５，反庆时间为４５ｍｉｎ，反应温度为２５℃，可膨胀石墨的含硫量为１．６３％时，膨胀容积为２５０ｍＬ／ｇ。其终端产品柔性石墨的含硫量为７８０ｐｐｍ。     

影响膨胀石墨膨胀容积因素的研究

以硫酸（98％）为插层剂、过氧化氢（30％）为氧化剂，用化学法制备膨胀石墨。通过正交实验确定最佳制备备件。结果表明：当石墨与硫酸重量比为1：3，硫酸与过氧化氢体积比为1：0．1，反应时间90min，反应温度50℃，膨化温度1000％，膨化时间20s时，膨胀石墨的膨胀容积可达250ml／g。     

制备无硫可膨胀石墨的研究

用硝酸（65％）和乙酸酐混合液、高锰酸钾和天然鳞片石墨反应制备无硫可膨胀石墨,最佳反应条件是：石墨、乙酸酐、硝酸、高锰酸钾的重量比为1：0．8：0．5：0．07,反应时间为40min,反应温度为30℃,可膨胀石墨的膨胀容积为280mL／g;不含硫,含氮量为1．27％,其终端产品柔性石墨不含氮．迄今为止,未见文献报道．     

制备低硫可膨胀石墨的新方法

研究了一种以冰醋酸为反应介质,在少量浓Ｈ２ＳＯ４存在下,以重铬酸钾作为氧化剂制备低硫可膨胀石墨的新方法。在最佳制备条件下,可膨胀石墨产品的含硫量仅为０．６８％,膨胀石墨产品的含硫量为０．０８％,膨胀容积２６０ｍＬ·ｇ－１,水分０．１０５％,挥发分５．５％,灰分０．７６％,ｐＨ值５,并采用紫外分光光度计对产品进行了分析。     

高倍率膨胀石墨的制备及性能表征

以鳞片石墨(0.300mm)为原料,高锰酸钾为氧化剂,采用化学氧化和分步插层的制备工艺,乙酸辅助插层,高温膨胀制备具有低硫高倍率膨胀石墨(EG),探讨其最佳工艺条件并对其性能进行了表征。结果表明:石墨(g)∶硫酸(ml)∶高锰酸钾(g)=1.0∶6.0∶0.2,反应温度40℃,反应时间为90min;乙酸辅助插层时间为120min,抽滤洗涤至pH值为5~7,60℃干燥烘干可膨胀石墨,900℃下高温膨胀30s,即可得高倍率膨胀石墨;膨胀石墨的性能表征对研究其吸附行为和机理有重要意义。     

以冰醋酸为介质制备低硫可膨胀石墨

以冰醋酸为介质，用酸性高锰酸钾作氧化剂制备低硫可膨胀石墨，筛选出制备的最佳条件，采用ＵＶ－Ｖｉｓ，ＸＲＤ等手段对石墨层间化合物予以分析。     

再次插入法制备超大膨胀体积石墨层间化合物(英文)

为进一步增大膨胀石墨的膨胀体积,用二次插入的方法制备了石墨层间化合物。首先用化学氧化法制备了膨胀体积为250mL/g的可膨胀石墨,然后以膨胀体积为250mL/g的可膨胀石墨为原料,用二次插入的方法制备了膨胀体积为380mL/g的膨胀石墨。讨论了各种反应物比率、反应温度和反应时间对膨胀体积的影响。对制得的膨胀石墨进行了各种表征,XRD谱显示产物保持了天然石墨的层状晶体结构,但是产物的石墨层间距离增大。扫描电镜照片显示通过二次插入石墨层间确实被进一步打开。结果显示这种新的制备方法是可行的,它为纳米石墨材料的研究提供了新的思路。     

HClO4-GIC的制备及其柔性石墨的性能

以天然鳞片石墨、高氯酸、硝酸为原料，采用化学法经插层、水洗、干燥、膨化等工艺过程制备膨胀石墨；以石墨蠕虫的膨胀体积为判据，采用正交实验方法确定工艺参数对石墨蠕虫膨胀体积的影响大小：探讨了反应温度、时间、膨化温度，GIC的挥发分对膨胀体积的影响；利用XRD表征了天然鳞片石墨、酸化石墨、柔性石墨的微观结构；利用EDS确定了插入物为HClO4；并对制备的柔性石墨的力学、电／热性能进行了测试。结果表明：工艺参数影响大小依次为反应温度、高氯酸／硝酸间的配比及反应时间、鳞片石墨／高氯酸间的配比。在较宽的温度范围内（室温～100℃），可容易地制备出GIC，且能在低温200℃下膨化。以最佳工艺条件：鳞片石墨：高氯酸：硝酸=1：4：0．15（质量比）制备的GIC，在200℃下膨化，可以制备出膨胀体积达360mL/g的膨胀石墨；在高温900℃下膨化，可以制备出膨胀体积达540mL/g的高倍膨胀石墨。石墨蠕虫经压制成型制备的柔性石墨的抗拉强度、电阻率同其表观体积密度存在密切的相关性，密度增加，抗拉强度增加，电阻率下降；其电阻率与导热率间也存在密切的相关性，电阻率下降，导热率提高，且其导热率高于同电阻率的人造炭／石墨材料的导热率。     

膨胀石墨对水面浮油的吸附性能

以硫酸为插层剂、过氧化氢为氧化剂,用化学法制备了膨胀石墨,分析了膨胀石墨对水面原油的吸附过程,测试了膨胀石墨对水面原油和齿轮油的最大吸附量。结果表明:膨胀石墨对水面原油和齿轮油的最大吸附量均与油的黏度和温度有关,最大吸附量随温度的升高而升高,随黏度的升高而降低。     

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.