功能材料二氧化钛光催化反应活性的研究

TiO2是一种高效节能的光催化功能材料,本文分析了TiO2光催化技术研究现状,探讨了光催化反应机制,并详细讨论了影响TiO2光催化反应活性的主要因素:(1)一般而言,锐钛矿型TiO2的光催化活性高于金红石型TiO2;(2)晶粒尺寸小,光生电子和空穴从TiO2体内扩散到表面的时间短,它们在TiO2体内的复合几率减小,光催化活性高;(3)金属离子掺入TiO2晶格中可能引起晶格位置缺陷或改变结晶度,抑制电子与空穴的复合,延长载流子的寿命,从而使光催化性能得以改善;(4)贵金属沉积可提高催化剂表面光生载流子的分离效率,有利于生成更多的·OH;(5)半导体耦合可提高系统的电荷分离效果,扩展对光谱吸收范围.     

Pb2+改性TiO2薄膜性能的研究

以玻璃为载体,采用溶凝胶胶法制备Pb2 -TiO2薄膜.采用AFM、XRD等技术,考察Pb2 掺杂后对TiO 2晶型结构和光催化活性的影响,结果表明,在相同制备条件下掺杂后使TiO2晶型由锐钛型向金红石型转变温度降低,经AFM分析,掺杂后使TiO2粒径增大,苯酚水溶液的光催化氧化分解反应结果表明,掺杂后TiO2的光催化活性有所提高.     

TiO2/SnO2复合薄膜的低温制备及其光催化性能

采用溶胶-凝胶法合成了TiO2溶胶和SnO2溶胶，使用浸渍提拉法在低温下制备出底层为金红石型SnO2，表层为锐钛矿型TiO2的复合膜．考察了不同SnO2薄膜层数对TiO2／SnO2复合膜光催化活性的影响，并对其光催化活性提高的机理进行了探讨．结果表明，SnO2层的加入能有效提高TiO2薄膜的光催化活性，随着SnO2薄膜层数的增加，光催化活性先增大后减小，但始终高于单一的TiO2薄膜．这是由于SnO2的导带电位低于TiO2的导带电位，SnO2的价带电位高于TiO2的价带电位，紫外光照下，TiO2中产生的光生电子注入到SnO2层，SnO2中空穴注入到TiO2层，有效抑制了薄膜内电子-空穴对的复合，增加了复合薄膜表面空穴的浓度，因而光催化活性得到了显著的提高．     

氧化钛基光催化材料的离子掺杂和酸化改性

本文基于光催化反应的机理分析,采用了金属离子掺杂和表面酸化相结合的改性方法对TiO2颗粒做了优化处理.对改性后的样品利用XRD、FTIR和PL等测试技术对样品进行了表征并以亚甲基兰为模拟污染物进行了光催化降解实验.结果表明包覆在粉体表面的新相以金红石为主;Fe离子掺杂降低了光生电子和空穴的复合几率;表面酸化增加了TiO2表面以双齿桥方式配位的羟基,此种羟基对TiO2光催化活性有重要影响;铁离子掺杂和表面酸化协同的改性方法可以明显提高TiO2粉体的光催化活性.     

Yb-TiO2光催化剂的制备及性能研究

采用溶胶-凝胶法制备了稀土Yb掺杂纳米TiO2光催化剂(Yb-TiO2),采用XRD、UV-Vis、FT-IR等方法对其进行表征和分析,并以亚甲基蓝(MB)作为目标降解物,考察了热处理温度以及Yb掺杂量对样品性能的影响。实验结果表明,Yb掺杂样品均为金红石相和锐钛矿相的混晶相,Yb的掺入拓展了TiO2对可见光的吸收范围,有效地抑制了光生电子-空穴对的复合,提高了TiO2的光催化活性。当pH值=2.5、n(Yb)∶n(Ti)=0.005、热处理温度为650℃时,制备的样品其光催化活性明显优于Degussa P25。     

钠离子对TiO_2薄膜结构及其光催化活性的影响

采用溶胶-凝胶浸渍提拉法在不同玻璃基板上制备TiO2薄膜,并通过降解浸渍在薄膜表面的甲基蓝来评价其光催化活性。利用X射线衍射(XRD)、X射线光电子能谱(XPS)和紫外-可见(UV-Vis)吸收光谱等研究了晶型、表面元素分析和光吸收性能。并采用平行电极法测定TiO2薄膜的光电流,研究了薄膜表面载流子的复合情况。结果表明,薄膜的催化性能主要与基板热扩散到薄膜中的Na+和晶相相关。Na+抑制锐钛矿相TiO2的形成,并且在一定条件下促进由锐钛矿向金红石相的转变。Na+的扩散对TiO2晶粒尺寸影响不大。重要的是,扩散至薄膜的Na+不仅影响TiO2薄膜的晶相转变,而且成为光生电子与空穴的复合中心,同时影响其光催化活性。     

La/TiO2-SiO2薄膜的光催化性能研究

采用溶胶-凝胶法制备了不同掺杂量的La／TiO2-SiO2复合薄膜．通过XRD、FE-SEM和AFM研究了复合薄膜的微观结构，采用紫外光照射下亚甲基蓝的分解实验比较薄膜的光催化性能．结果表明：La掺杂可显著提高TiO2-SiO2复合薄膜的光催化活性，以5％掺杂量为最佳，其光降解率比掺杂前提高了约23％．薄膜活性提高的主要原因是La掺杂后细化了TiO2的晶粒，提高了薄膜的比表面积，使其具有更高的氧化还原电势，La^3＋取代Ti^4＋进入到TiO2晶格，引起晶格膨胀，这种不同价离子的取代导致TiO2粒子表面电荷分布不平衡，从而提高了光生电子-空穴的分离效率．     

稀土掺杂TiO2光催化材料的制备和性能

采用溶胶-凝胶法制备了5种稀土（Pr、Nd、Sm，Eu、Dy）掺杂TiO2光催化薄膜，研究了稀土掺杂量，镀膜层数、烧结温度和烧结时间对光催化活性的影响．结果表明，各因素对材料的催化活性均存在一最佳值．薄膜中仅含TiO2而未见稀土氧化物，除掺锴TiO2薄膜完全由金红石相组成外，其余均由锐钛矿相和金红石相的混晶组成，其中金红石相所占比例较大，薄膜表面均存在大量缺陷；稀土掺杂TiO2薄膜对罗丹明B的光降解率可达89．3％．稀土掺杂TiO2显著提高了TiO2对可见光的响应能力，提高了材料的光催化活性．     

金红石二氧化钛纳米片的性质及其光催化活性

采用溶胶-凝胶、质子交换和层状剥离的方法, 制备出金红石TiO₂纳米片。利用X射线电子衍射谱(XRD)、透射电子显微镜(TEM)、紫外-可见吸收光谱(UV-Vis)、X光电子能谱(XPS)的价带谱和荧光光谱(PL)等对样品进行了表征, 研究了光生载流子的转移过程。结果证明: 金红石TiO₂纳米片具有较大的比表面积(185.7 m²/g), 厚度约5 nm, 与金红石TiO₂样品相比, 金红石TiO₂纳米片的禁带宽度增加, 氧化还原能力增强; 此外, 纳米片结构能够促使光生载流子快速转移到纳米片的表面并产生有效分离, 阻止了光生电子和空穴的复合, 提高了光催化反应中光生载流子的利用率。金红石纳米片的这些特性导致其具有较高的光催化活性, 紫外光催化降解对氯苯酚的实验表明: 金红石TiO₂纳米片的光催化活性高于金红石TiO₂和锐钛矿TiO₂样品。     

Sb对直流反应磁控溅射制备TiO2薄膜的影响

用直流磁控溅射方法在Si(100)面及载玻片上制备了Sb掺杂TiO2薄膜.利用XRD光谱研究了Sb对其薄膜结晶情况的影响,用AFM观察其表面形貌,利用分光光度计测量了TiO2薄膜的光学特性及其对亚甲基蓝的分解活性,通过测量和计算表面对水的接触角来衡量光致亲水性.研究结果表明纯TiO2薄膜为锐钛矿型,适量Sb的掺杂能使TiO2薄膜的结晶有显著改善,并出现Ti2O3和金红石相TiO2,薄膜的光催化活性和光致亲水性明显改善.随着掺杂量的增加,TiO2薄膜的吸收边逐渐红移.但Sb掺杂过量时,破坏了二氧化钛原有的晶格结构,光催化活性和光致亲水性也相应降低.     

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.