多铁材料BiFeO3的制备与表征

以硝酸铁和硝酸铋为反应物,柠檬酸为络合剂,硝酸为催化剂,采用柠檬酸溶胶–凝胶法制备粒径分布均匀的多铁性材料BiFeO3纳米粉体,通过TG-DSC、XRD、FT-IR、SEM及AFM等手段对样品的结构、形貌及纯净度进行表征.研究结果表明,在溶胶过程中前驱液的pH值以及干凝胶的煅烧温度等合成条件对BiFeO3纳米粉体的制备和纯净程度都有一定的影响,最佳的合成条件是前驱溶液的pH=7～8,干凝胶的煅烧温度为600℃.在该条件下得到的BiFeO3纳米粉体中无杂相Bi25FeO40和Bi2Fe4O9等,纳米颗粒尺寸在100 nm左右,分散性良好,饱和磁化强度Ms=1.08 A·m2/kg,剩余磁化强度Mr=0.13 A·m2/kg,矫顽力Hc=15.76 kA/m.     

溶胶-凝胶法制备PZT(95/5)反铁电纳米粉

采用溶胶-凝胶法制备Pb(Zr0.95Ti0.05)O3(简称PZT(95/5))反铁电纳米粉,差热分析确定干燥后粉体的煅烧温度范围为550~750℃。将干燥后粉体分别在550,600,650,750℃下煅烧,保温2 h,经XRD分析发现,随着煅烧温度的升高,主晶相的强度逐渐升高,杂质相的峰高逐渐减弱。当煅烧温度为750℃时,形成了完全的钙钛矿相。所制PZT95/5粉体的平均粒径约100 nm。     

退火工艺对液相自组装法制备BiFeO3薄膜的影响

以Bi(NO3)3·5H2O,Fe(NO3)3·9H2O和柠檬酸为主要原料,采用液相自组装法,以OTS单分子层为模板,在ITO玻璃基片上成功制备了BiFeO3晶态薄膜.研究了退火温度以及保温时间对BiFeO3薄膜的影响.利用DSC/TG对铁酸铋前驱物结晶行为进行了表征,利用XRD和FE-SEM等测试手段对不同退火工艺下...     

高能球磨Al-Y203粉体固相反应制备YAG陶瓷的研究

用高纯Al粉体和Y2O3粉体(Al-Y2O3粉体)为原料采用固相反应法制备了YAG陶瓷. Al-Y2O3粉体高能经过球磨,煅烧生成YAG粉体,再真空烧结制备高致密YAG陶瓷.采用DTA-TG对球磨Al-Y2O3粉体进行分析,采用XRD、SEM对球磨的Al-Y2O3粉体、YAG粉体及YAG陶瓷进行了表征.实验表明:Al-Y2O3粉体在～569℃时,Al粉强烈氧化,并与Y2O3粉反应,600℃煅烧出现YAM相,随煅烧温度升高出现YAP相,1200℃煅烧生成YAG粉体.成型YAG素坯在1750℃保温2h真空烧结出YAG相陶瓷,YAG陶瓷相对密度可达98.6%,晶粒生长均匀,晶粒尺寸为8～10μm.     

化学共沉淀法制备纯相BiFeO_3粉体

以Bi(NO_3)_3·5H_2O和Fe(NO_3)_3·9H_2O为原料,稀硝酸为溶剂,氢氧化钠作为沉淀剂,采用化学共沉淀法制备铁酸铋前驱体,对前驱体进行煅烧处理得到BiFeO_3粉体。研究了沉淀体系pH值和煅烧工艺对BFO结构及光催化性能的影响。采用XRD、SEM对所制备的BFO粉体进行了表征。结果表明,沉淀体系pH值为8~11范围内,并于600℃下煅烧2h可得到纯相BFO粉体。该粉体具有优异的可见光催化性能,且随BFO的晶粒尺寸增大,其可见光催化降解率提高。     

水热法制备K0.5 Bi0.5 TiO3纳米粉体

以Bi(NO3)3·5H2O、Ti(OC4H9)4、KOH为原料,研究和分析了水热条件下纳米K0.5Bi0.5TiO3(KBT)粉体和影响KBT晶体生长与形成的各个影响因素,并利用XRD、TEM、ED等分析方法对所得粉体的晶相、微观形貌、分散性等性质进行了表征.结果表明,反应温度为180℃,保温时间为24h,KOH浓度为4～12mol/L时能制备出纯净的、结晶完整、分散性良好、钙钛矿型的纳米K0.5Bi0.5TiO3晶体,其颗粒尺寸为15～75nm.     

Bi_(12)TiO_(20)粉体的制备及性能研究

采用化学溶液分解法制备了Bi12TiO20粉体.通过XRD及光催化降解甲基橙的分析,研究了制备条件对光催化活性的影响.结果表明,在可见光下,前驱体溶液浓度为0.25mol/L,加热温度为70℃,加热时间为3h,煅烧温度为500℃,煅烧时间为2h时,所制备粉体的光催化活性最好,其光催化降解甲基橙的降解率除个别样品外均大于德国Degussa P25.制备出的Bi12TiO20材料的带隙能约为2.28eV.     

柠檬酸溶胶-凝胶法制备Ca3Co4O9粉体及结构表征

以柠檬酸为络合剂,采用溶胶凝胶法,制备了Ca3Co4O9 粉体,通过差热分析(TG DTA)、红外光谱(FT IR)、扫描电子显微镜(SEM)、选区电子衍射(SAD)、高分辨电子显微镜(HRTEM)、能谱(EDX)等手段对Ca3Co4O9 进行表征。实验结果表明,干凝胶的煅烧温度在750~900℃之间,时间2h,可制备纯相Ca3Co4O9 粉体。该粉体为粒径100~200nm 的片状单晶。     

高能球磨Al-Y2O3粉体固相反应制备YAG陶瓷的研究

用高纯Al粉体和Y₂O₃粉体(Al-Y₂O₃粉体)为原料采用固相反应法制备了YAG陶瓷. Al-Y₂O₃粉体高能经过球磨, 煅烧生成YAG粉体, 再真空烧结制备高致密YAG陶瓷. 采用DTA-TG对球磨Al-Y₂O₃粉体进行分析, 采用XRD、SEM对球磨的Al-Y₂O₃粉体、YAG粉体及YAG陶瓷进行了表征. 实验表明: Al-Y₂O₃粉体在～569℃时, Al粉强烈氧化, 并与Y₂O₃粉反应, 600℃煅烧出现YAM相, 随煅烧温度升高出现YAP相, 1200℃煅烧生成YAG粉体. 成型YAG素坯在1750℃保温2h真空烧结出YAG相陶瓷, YAG陶瓷相对密度可达98.6%, 晶粒生长均匀, 晶粒尺寸为810μm.     

BiFeO_3的水热合成、表征及光催化性能研究

以Bi(NO3)3.5H2O和Fe(NO3)3.9H2O为原料,KOH为矿化剂,聚乙二醇6000为分散剂,水热合成了单相BiFeO3粉体,利用X射线衍射、扫描电镜优化了水热合成条件,利用振动样品磁强计测定了BiFeO3的磁滞回线,并对产物进行了光催化降解甲基橙性能的研究。结果表明,200℃条件下反应6h制备的BiFeO3粉体显顺磁性,紫外光照射4h对甲基橙的降解率可达90%。     

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 Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

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.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

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.     

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.