表面有阳极氧化层的氘化钛热解吸动力学研究

应用反应速率分析方法,测定了氘化钛和表面有阳极氧化层的氘化钛在恒容体系和600～800℃范围内的热解吸反应速率常数,得到氘化钛和阳极氧化的氘化钛热解吸氘的活化能分别为(24.9±1.0)kJ/mol和(38.5±1.2)kJ/mol;氘化钛表面氧化层越厚,表观活化能越大;实验表明氘化钛表面阳极氧化层具有阻氘性能.     

攀枝花产海绵钛氢化脱氢动力学

通过压力组成等温曲线测试仪(PCT)测试了工业海绵钛在400~600℃温度下的吸放氢特性。应用反应速率分析方法计算了实验温度下的反应速率常数,并通过阿伦尼乌斯方程计算出实验条件下海绵钛吸放氢表观活化能。经过完全活化后,海绵钛吸氢表观活化能为(34.42±0.02)kJ/mol,氢化钛粉的脱氢表观活化能为(29.93±0.01)kJ/mol。这个结果表明,氢原子在金属相间的扩散速率是控制海绵钛氢化与脱氢反应的主要因素。     

酚醛树脂-双马来酰亚胺体系的固化动力学

采用非等温DSC法探讨了酚醛树脂与双马来酰亚胺体系的固化反应,在30 ℃～400 ℃范围内以不同升温速率(5 ℃/min、10 ℃/min、15 ℃/min、20 ℃/min)进行动态固化行为分析.应用Kissinger、Crane和Ozawa法求得了固化反应的表观活化能、固化反应级数、凝胶温度和固化温度等动力学参数.结果表明,固化体系的平均表观活化能为109 kJ/mol,反应级数为0.94,凝胶温度Tgel为79.68 ℃,固化温度Tcure为121.93 ℃,表观活化能E是固化度α的增函数.     

真空碳热还原钛精矿中铁的等温动力学北大核心CSCD

采用等温动力学研究的方法在1100~1300℃下对攀枝花钛精矿真空碳热还原中铁的动力学进行了研究。研究结果表明:还原温度的升高和保温时间的延长,能促进钛精矿中Fe3O4的还原以及铁的聚集长大;钛精矿中的铁在1100~1250℃保温的前期即0~30 min时,还原反应受界面化学反应控制,反应的表观活化能为207.92 kJ/mol;在1100~1200℃保温的后期即30~90min时,还原反应受内扩散控制,反应的表观活化能为521.47 kJ/mol。     

真空碳热还原钛精矿中铁的等温动力学

采用等温动力学研究的方法在1100～1300℃下对攀枝花钛精矿真空碳热还原中铁的动力学进行了研究。研究结果表明:还原温度的升高和保温时间的延长,能促进钛精矿中Fe_3O_4的还原以及铁的聚集长大;钛精矿中的铁在1100～1250℃保温的前期即0～30 min时,还原反应受界面化学反应控制,反应的表观活化能为207.92 kJ/mol;在1100～1200℃保温的后期即30～90min时,还原反应受内扩散控制,反应的表观活化能为521.47 kJ/mol。     

储氢材料67Mg29C3Ni1Al的放氢动力学研究

采用氢气反应球磨法,将煤基微晶碳及少量Ni和Al添加到镁粉中在1MPa氢气中球磨3h制得储氢材料67Mg29C3Ni1Al.放氢测试结果表明,温度越高,放氢速度越快,放氢量越大,数据拟舍得出放氢反应为表观一级反应.根据阿伦尼乌斯方程计算得出,在300～350℃范围内,放氢反应表观活化能为(138.0±6)kJ/mol.与储氢材料70Mg30C及纯MgH2相比,微晶碳和催化剂Ni、Al缩短了储氢材料的放氢时间,加快了放氢速度,提高了放氢量,降低了表观活化能,放氢动力学性能得到了改善.     

苯并噁嗪-酚醛-环氧豆油三元聚合体系的热分解行为研究

通过热重分析法研究了苯并噁嗪-酚醛-环氧豆油(BA-NP-ESO)三元聚合体系在不同升温速率下的热分解动力学。利用Kissinger-Akahira-Sunose(KAS)法和Flynn-Wall-Ozawa(FWO)法求取了三元聚合体系热分解过程的表观活化能,当分解率在0.3～0.9范围内时,反应属于同一机理,两种方法求得的活化能分别为241.1kJ/mol和253.7kJ/mol。运用Coats-Redfern法和Achar法对非等温动力学数据进行分析,得到热分解反应的机理函数,其热分解反应为四级反应,符合随机成核和随后生长机理,两种方法求得的表观活化能分别为250.21kJ/mol和266.96kJ/mol,与KAS和FWO法的结果较为一致。     

碳助磨制备纳米镁铝储氢合金的结构及储氢性能研究

以改性无烟煤为助磨剂,在氢气气氛下球磨制备了具有纳米结构的镁铝合金储氢材料,通过SEM,XRD,TPD等手段对比研究了球磨吸氢材料及静态再吸氢材料的晶相结构及放氢动力学性能.结果表明:改性无烟煤具有良好的助磨作用,经5.5h球磨,材料平均粒度可达74nm;镁铝合金经反应球磨后,其中的Mg转化成了β-MgH2和γ-MgH2,放氢峰温低于300℃;静态再吸氢后,MgH2全部以β-MgH2存在,且晶体粒度增长60％,Mg17Al12分解为单质Mg和Al,其中单质Al使储氢材料放氢活化能降低,用Kissinger方程计算出球磨储氢和再吸氢材料的放氢一级表观活化能分别为107.3kJ/mol和67.1kJ/mol.     

烟煤粘结纳米镁基储氢材料的制备及吸放氢性能

以Mg、烟煤和碳化无烟煤为原料,经H2反应球磨、热处理制备了烟煤粘结的纳米镁基储氢材料,研究了储氢材料结构及吸放氢性能,并计算了材料的吸氢动力学参数。结果表明,在600℃热处理时材料中的Mg容易与煤中的C发生反应生成Mg2C3;添加15%(质量分数)烟煤,经500℃热处理能有效粘结纳米Mg颗粒,且未见Mg2C3生成。储氢材料的吸氢速率随温度升高而增大,在2MPa H2下吸氢量在350℃达到最大值,约3.77%(质量分数),在400℃时吸氢量略有下降。根据Arrhenius公式得出储氢材料在300~350℃下吸氢的一级反应表观活化能为56.6kJ/mol H2。用TPD测定了储氢材料的放氢温度,表明材料在250℃开始放氢,388℃时达到放氢高峰。储氢材料中的C可结合少量H,该类H在加热时会以CH4等烃的形式释放出来。     

热分析在PVA纤维预处理中的应用

用差热、热重法对原丝的热性能及由不同预处理方法所引起的PVA纤维的热行为变化进行了研究;并通过模拟脱水条件,用不同升温速率,求出了经不同预处理纤维的脱水反应活化能。结果表明,PVA原丝在230℃有一软化点,三种预处理都不同程度地影响了原丝的热效应变化;纤维在180～340℃主要为脱水反应;原丝及经脱水剂、O_3和O_3综合脱水剂处理的纤维,其脱水反应的表观活化能分别为:164.3kJ/mol,92.9kJ/mol,130.5kJ/mol和117.6kJ/mol。     

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.