微波熔盐法合成片状晶体SrTiO3

采用在熔盐法中引入微波场的人工晶体生长新技术，在低温下成功地合成出了片状晶体SrTiO3。首先在助熔剂NaCl-KCl中合成片状前驱体Sr3Ti2O7，然后在片状晶体Sr3Ti2O7上外延生长制备出片状晶体SrTiO3，采用XRD和SEM分析产物的结构。结果表明，利用微波熔盐法在750℃保温3h得到了尺寸为10μm的片状Sr3Ti2O7，将前驱体Sr3Ti2O7和TiO2在微波场中于700℃保温2h得到了10～20μm的片状晶体SrTiO3。和常规熔盐法相比，微波熔盐法降低了SrTiO3的合成温度，节省了晶化时间，大幅度地降低了能耗。     

两步熔盐法合成片状SrTiO3

以SrCO3和TiO2为原料,采用两步熔盐法合成出片状SrTiO3.首先在助熔剂NaCl中,1300℃保温6h合成出片状中间体;然后以片状中间体为模板晶粒,在助熔剂KCl中,1200℃保温4h制备出片状SrTiO3.所得产物过筛后,采用X射线衍射(XRD)和扫描电镜(SEM)分析粉体的相组成和显微结构,结果表明:中间体是由各向异性的Sr3Ti2O7、Sr4 Ti3O10、Sr2TiO4和各向同性的SrTiO3晶粒组成,而且各向异性晶粒的(001)和(200)峰均增强,片状晶粒为长方形,边长为40～60μm.SrTiO3粉体的相组成为纯钙钛矿相,其它杂相组分未曾检出,而且＞5μm粉体的(200)峰增强,说明该粉体为片状晶粒,呈正方或长方形,边长约为50μm.     

两步熔盐合成技术制备片状SrTiO3晶体

采用两步熔盐法制备钙钛矿结构的片状SrTiO3晶体,利用XRD、SEM等手段研究了Sr3T2O7和SrTiO3晶粒的形成过程和微观形貌.结果表明,在SrCO3-TiO2-KCl体系中,片状Sr3Ti2O7的形成分两步进行,先由SrCO3、TiO2反应生成细小的Sr3Ti2O7相颗粒,再通过溶解一析出反应进行晶粒取向性生长,最终成为以(001)为主面的片状晶粒.1200℃保温4h后得到长10～20μm、厚约3μm的片状Sr3Ti2O7晶体.在Sr3Ti2O7-TiO2-KCl体系中,发现含Ti、Sr、O、K的晶须状中间化合物,同时出现较多等轴状SrTiO3颗粒,而且片形SrTiO3晶体较其前驱体Sr3Ti2O7有所增厚.这表明片形SrTiO3晶体的形成主要是Sr3Ti2O7因Sr、O析出产生切变而成,TiO2能够促进Sr3Ti2O7中Sr、O的析出,KCl熔盐同时起着传质介质和反应助剂的作用.     

工艺参数对熔盐法制备Bi4Ti3012的影响

为了获得片状粉体用于无铅压电陶瓷晶粒的定向生长，采用NaCl-KCl熔盐法制备了各向异性的片状Bi4Ti3O12粉体，研究了预烧温度和熔盐含量对粉体的显微组织结构和形貌各向异性的影响，计算了粉体径向尺寸与厚度尺寸的比值以表征粉体的各向异性．研究表明：随着预烧温度的升高，粉体尺寸不断增加，各向异性逐渐增大，最佳预烧温度为950℃；采用熔盐法可制备出纯Bi4Ti3O12相粉体，随熔盐含量增加，钛酸铋粉体尺寸及各向异性程度明显增大，并在烧结后的Bi4Ti3O12陶瓷中有织构产生．     

工艺参数对熔盐法制备Bi4Ti3O12的影响

为了获得片状粉体用于无铅压电陶瓷晶粒的定向生长,采用NaCl-KCl熔盐法制备了各向异性的片状Bi4Ti3O12粉体,研究了预烧温度和熔盐含量对粉体的显微组织结构和形貌各向异性的影响,计算了粉体径向尺寸与厚度尺寸的比值以表征粉体的各向异性.研究表明:随着预烧温度的升高,粉体尺寸不断增加,各向异性逐渐增大,最佳预烧温度为950℃;采用熔盐法可制备出纯Bi4Ti3O12相粉体,随熔盐含量增加,钛酸铋粉体尺寸及各向异性程度明显增大,并在烧结后的Bi4Ti3O12陶瓷中有织构产生.     

熔盐法制备片状钛酸铋粉体的研究

采用NaCl-KCl熔盐法制备了生长各向异性的片状Bi4Ti3O12粉体.研究了预烧温度及熔盐含量对粉体形貌及显微结构的影响.结果表明,750℃预烧所得Bi4Ti3O12粉体为单一的钙钛矿型结构,随熔盐含量的增加,Bi4Ti3O12粉粒的尺寸及生长的各向异性程度均有所增大,预烧温度的增加也促进了粉粒的生长,获得明显生长各向异性的钛酸铋粉体的最佳预烧温度为950～1000℃.     

乙二醇溶剂热合成自组装SrTiO3片状纳米结构及其光催化性能

以钛酸四正丁酯((C4H9O)4Ti)水解沉淀的钛羟基氧化物和硝酸锶(Sr(NO3)2)为反应原料,以氢氧化钾(KOH)为矿化剂,以乙二醇((HOCH2)2)为溶剂,经200℃溶剂热反应得到了由纳米颗粒自组装形成的SrTiO3片状纳米结构。分别用XRD、SEM、TEM表征SrTiO3粉体的物相结构和微观形貌。通过光催化降解罗丹明B(RhB)对比研究了乙二醇溶剂热合成的纳米颗粒自组装SrTiO3片状纳米结构和水热合成的SrTiO3粉体的光催化性能,结果表明,乙二醇溶剂热合成的SrTiO3自组装片状纳米结构具有更加优异的光催化性能。     

非化学计量Bi2O3对制备Bi4Ti3O12粉体影响的研究

制备晶粒形貌生长各向异性的中间化合物Bi4Ti3O12粉体是采用流延成型和模板晶粒生长(TGG)等工艺方法制备(Na0.5Bi0.5)TiO3基无铅压电织构陶瓷的关键技术.以NaCl-KCl熔盐法制备了生长各向异性的Bi4Ti3O12粉体,利用X射线衍射和扫描电子显微镜研究了非化学计量Bi2O3对粉体相结构和微观形貌的影响,优化了制备Bi4Ti3O12粉体的工艺参数,并探讨了Bi4Ti3O12粉体在熔盐中的生长机理.研究表明,随着Bi2O3过量程度的增加,所得Bi4Ti3O12粉体颗粒的平均尺寸和均匀程度均增加,当Bi2O3过量7.5%时达到最佳值,其平均粒径为8～10 μm.     

Ba0.8Sr0.2Ti0.5Mn0.5O3纳米晶体的合成及气敏性质研究

采用复合碱媒介法(CHM),在合成BaMnO3和Ba0.5Sr0.5MnO3的基础上,以Sr(NO3)2、BaCO3以及MnO2和TiO2为原料,在200℃、24h的生长条件下,用20%的Sr离子替代20%的Ba离子,用50%的Ti离子替代50%的Mn离子成功合成了Ba0.8Sr0.2Ti0.5Mn0.5O3纳米晶体。采用XRD、SEM及EDS对产物的晶相、形貌和成分进行了分析,对Ba0.8Sr0.2Ti0.5Mn0.5O3制作的电极进行了气敏性质的测定。     

离子阱中过渡金属Ti~ ,Co~ 与O_2的化学反应

利用激光溅射的方法产生并在射频离子阱中囚禁了Ti＋，Co＋离子，利用离子阱的质量选择存储和离子存储时间长等特点，开展了Ti＋，Co＋与O2的化学反应研究，得到了反应物的速率常数和反应产物分支比。结果表明，Co＋比Ti＋具有更大的化学活性，并且其二级产物（CoO2＋）具有更大的解离速率，因而更具有催化特性。     

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.