苯并噁嗪/POSS纳米复合材料的合成与性能研究

以双酚A、多聚甲醛、11-氨基十一酸和环氧化POSS为原料合成了苯并噁嗪-POSS纳米复合材料。采用傅里叶红外光谱、差示扫描量热仪和热重分析分别对其结构、热固化行为和热稳定性进行表征。结果表明:随着POSS含量的增加,其固化起始温度和终止温度呈下降趋势,苯并噁嗪树脂的热稳定性能随之提高,当POSS含量为5%时,双酚A-POSS苯并噁嗪树脂的残炭量达到最大为23.0%。     

聚苯并噁嗪／不完全笼型倍半硅氧烷复合材料的性能研究

制备了双酚A型苯并噁嗪（BZ）／不完全笼型苯基三羟基七聚倍半硅氧烷（（C6H5）7SiO9（OH）3（T7POSS））杂化树脂,并对其固化行为、固化所得复合材料的热性能和动态力学性能进行了表征,差示量热扫描仪（DSC）测试表明,T7POSS能显著降低体系的起始固化温度;动态粘弹分析仪（DMA）、热重分析仪（TGA）测试表明。T7POSS提高了体系的储能模量、玻璃化转变温度Tg和热稳定性。     

RTM改性苯并噁嗪树脂及复合材料性能研究

研究了RTM改性苯并噁嗪树脂及复合材料性能.用DMA研究RTM改性苯并噁嗪树脂体系的储能模量、损耗模量和玻璃化转变温度;用流变仪研究黏度特性;用TGA和TGA微分曲线研究热分解性能;并研究了RTM改性苯并噁嗪树脂及复合材料的力学性能.结果表明:RTM改性苯并噁嗪树脂体系的玻璃化转变温度是206℃;至少有400min的低黏度(η≤0.5Pa.s)时间作为工艺开放期;在氮气气氛下,RTM苯并噁嗪树脂体系热失重分两个主要阶段,在375℃时发生5％热失重,800℃残碳率是45.2％;RTM苯并噁嗪树脂基体拉伸强度72.4MPa,拉伸模量5.07GPa,弯曲强度173MPa,弯曲模量4.6GPa;碳纤维增强RTM苯并噁嗪树脂基复合材料的常规力学性能优异.     

低介电笼型倍半硅氧烷改性氰酸酯-环氧树脂复合材料

采用环氧基倍丰硅氧烷(POSS)对双酚A型氰酸酯和环氧树脂共聚体系进行改性.系统研究了该固化体系的纳米粒子相分散状态、热性能以及力学性能、介电性能.当POSS含量为1%(质量分数)时,POsS以分子级分散在树脂基体中,该固化体系的热性能和机械性能均有明显提高,介电常数和介电损耗显著降低.随着POSS含量的提高,部分POSS以自聚和结晶的状态存在于聚合物中,体系的热性能和机械性能有所下降.     

RTM用苯并(恶)嗪树脂基碳纤维复合材料的性能研究

针对RTM成型工艺对基体树脂的特殊要求,结合MA型苯并(噁)嗪树脂耐烧蚀、高性能的特点,对制造高强度苯并(噁)嗪树脂基碳纤维复合材料进行了研究.系统考察了基体树脂体系的工艺性能、固化反应行为以及力学性能.结果表明:该树脂体系在95～115℃温度区间内至少有350min的低黏度(≤500mPa·s)时间作为工艺开放期,符合RTM成型工艺要求;树脂体系的玻璃化转变温度在223℃;RTM苯并(噁)嗪树脂基碳纤维复合材料的空隙含量仅为0.23％,树脂浇铸体和碳纤维复合材料的常规力学性能优异.MA型苯并(噁)嗪树脂完全可以采用RTM工艺成型高性能复合材料.     

高性能苯并(噁)嗪基复合材料研究进展

综述了近年来国内外在苯并(噁)嗪树脂基复合材料方面的研究进展,重点介绍了以苯并(噁)嗪为基体的复合材料在耐热、增韧、增强等方面包括化学改性和物理共混研究进展,并初步判断了今后以苯并(噁)嗪树脂为基体的复合材料的发展方向.     

低介电常数苯并噁嗪树脂的合成

以双酚A、甲醛分别和苯胺、间甲苯胺、对甲苯胺、3,5-二甲基苯胺为原料合成苯并噁嗪树脂.通过对比固化后树脂的介电常数,表明苯胺苯环上甲基的存在和不同位置对苯并噁嗪固化树脂介电常数存在影响.同时采用在树脂中引入氟原子的方法来降低树脂的介电常数.以甲醛、3,5-二甲基苯胺和双酚AF为原料合成了一种介电常数为2.93(1MHz),玻璃化转变温度为287℃的苯并噁嗪树脂.     

苯并噁嗪共混树脂及其玻璃纤维布增强复合材料的制备与性能

采用氨基保护和还原方法合成了对氨基苯炔丙基醚(APPE),与苯酚和多聚甲醛通过Mannich缩合制备了含炔丙基的苯并噁嗪(P-APPE).采用溶液共混的方法,将P-APPE与苯酚/苯胺型苯并噁嗪(PAF)和含硅芳炔树脂(PSA)共混得到了改性苯并噁嗪树脂.用差示扫描量热法、动态热力学分析、热失重分析和宽频介电仪研究了该树脂体系的热性能和介电性能.研究结果表明:PSA加入到苯并噁嗪树脂中可提高共混树脂的热性能,加入质量分数为14.3％的PSA可使共混树脂的Tg从195℃提高至235℃,其5％热失重温度从350℃提高至399℃;共混树脂的介电损耗因子和介电常数随PSA加入量的增加而降低.玻璃纤维布增强的共混树脂复合材料的层间剪切强度和弯曲强度在加入质量分数为5.3％的PSA后下降超过50％.     

苯并噁嗪共混树脂及其玻璃纤维布增强复合材料的制备与性能

采用氨基保护和还原方法合成了对氨基苯炔丙基醚(APPE), 与苯酚和多聚甲醛通过Mannich缩合制备了含炔丙基的苯并噁嗪(P-APPE)。采用溶液共混的方法, 将P-APPE与苯酚/苯胺型苯并噁嗪(PAF)和含硅芳炔树脂(PSA)共混得到了改性苯并噁嗪树脂。用差示扫描量热法、动态热力学分析、热失重分析和宽频介电仪研究了该树脂体系的热性能和介电性能。研究结果表明: PSA加入到苯并噁嗪树脂中可提高共混树脂的热性能, 加入质量分数为14.3%的PSA可使共混树脂的 T _g从195℃提高至235℃, 其5%热失重温度从350℃提高至399℃; 共混树脂的介电损耗因子和介电常数随PSA加入量的增加而降低。玻璃纤维布增强的共混树脂复合材料的层间剪切强度和弯曲强度在加入质量分数为5.3%的PSA后下降超过50%。     

一种中低温注射成型改性苯并噁嗪树脂的研究

以苯酚-苯胺型苯并噁嗪(P)、对羟基苯甲醛-苯胺型苯并噁嗪(B)、环氧F-51和固化剂#594为原料,采用共混的方式制备了树脂传递模塑(Resin Transfer Molding,RTM)用树脂体系.研究结果表明,该树脂体系在低温下(40℃)即可达到使用要求,且树脂体系的稳定性良好,在5h内黏度基本保持稳定;树脂体系固化物具有较好的耐热性能,Tg为167℃.采用双Arrhenius方程建立了树脂体系的化学流变学模型,经计算求得树脂体系的加工窗口为39～60℃.通过DSC研究确定了树脂体系中的固化反应顺序依次为:环氧基团反应、噁嗪环的开环及与环氧的共聚等反应.     

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.