氟硅油用作高温航空润滑油的研究

对氟硅油的性能进行了研究,主要包括热氧化安定性、润滑性和黏温性能等.结果表明:氟硅油的热氧化稳定性温度可达250℃;通过分子结构中引入了Cl元素,其润滑性能得到明显的提高;此外还具有优异的黏温性能和低温性能.该油的最高使用温度比酯类油提高了50℃以上.     

氟硅油高温性能的研究

对氟硅油的高温性能,包括热氧化安定性、粘度－温度性能、高温蒸发损失、与橡胶的相容性、润滑性等进行了研究,并同国外同类产品和国内的酯类航空润滑油进行了比较。研究结果表明,氟硅油的热氧化安定性明显优于酯类油。通过加入合适的抗氧剂,其热氧化安定性还可明显提高。     

1,3,5-三甲基-1,3,5-三(3′,3′,3′-三氟丙基)环三硅氧烷的阴离子开环(共)聚合研究进展

1,3,5-三甲基-1,3,5-三(3′,3′,3′-三氟丙基)环三硅氧烷(F3)的阴离子开环聚合可以合成优越耐油耐溶剂性能的聚甲基三氟丙基硅氧烷(PMTFPS),但在开环聚合过程中“反咬”与再分布副反应严重,要得到高分子量、高产率的氟硅聚合物材料,必须严格控制聚合反应条件。文中总结了本体、溶液、细乳液中F3的阴离子开环聚合影响因素、机理与动力学,以及F3与其它单体共聚合反应等方面的研究进展。     

聚甲基三氟丙基硅氧烷合成的研究进展

聚甲基三氟丙基硅氧烷(PMTFPS)可通过1,3,5-三甲基-1,3,5-三(3′,3′,3′-三氟丙基)环三硅氧烷(D3F)的阴离子开环聚合制备。归纳总结了PMTFPS合成方法的最新研究进展,主要从聚合机理、工艺条件的研究进行了总结与分析;并对合成方法目前存在的问题和发展方向进行了展望。     

溶剂法醇解合成3,3,3-三氟丙基三甲氧基硅烷的研究

以3,3,3-三氟丙基三氯硅烷和甲醇为原料,采用溶剂法醇解合成3,3,3-三氟丙基三甲氧基硅烷,研究了原料配比、N2流量、滴加速度、反应温度及反应时间等因素对合成的影响,运用GC-MS、FT-IR等手段对反应过程和结果进行了综合分析,提出了最佳合成条件.     

多功能基共改性聚甲基三氟丙基硅氧烷的合成表征与膜形貌

通过聚甲基三氟丙基含氢硅氧烷与端烯丙基聚氧乙烯醚、丙烯酸十八醇酯、烯丙基缩水甘油醚的硅氢化加成反应,制备了一种十八酯基/聚醚/环氧基共改性聚甲基三氟丙基硅氧烷(PSA-PFMS)。用红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、场发射扫描电镜(FESEM)、原子力显微镜(AFM)等仪器分别对PSA-PFMS的结构、成膜形态及性能进行表征和研究。结果表明,在棉纤维和单晶硅表面,PSA-PFMS均可成膜。在单晶硅表面,可形成粗糙度大(2μm×2μm的扫描范围内,硅膜的均方粗糙度达1.197 nm)、呈微观相分离结构的疏水膜。该膜附着在纤维表面,能使处理后织物表面水的静态接触角达到129.2°。     

3,3,3-三氟丙基三甲氧基硅烷的合成研究

以3,3,3-三氟丙基三氯硅烷和甲醇为原料,采用溶剂法合成3,3,3-三氟丙基三甲氧基硅烷,讨论了氮气流速、反应温度、原料配比、溶剂种类、滴加方式等因素对产物收率的影响.并用GC-MS对产物进行了分析.通过实验得出该反应较优的反应条件为:用正己烷作溶剂,N2流速为100mL/min,3,3,3-三氟丙基三氯硅烷和甲醇的摩尔比为1∶3.1,反应温度在70℃左右,3,3,3-三氟丙基三甲氧基硅的产率可达89.4%.     

4-氰基-3,5,2′-三氟-4′-(反-4″-正丙基环己基)联苯的合成

以4-正丙基环己酮,3-氟溴苯和液晶中间体4-溴-2,6-二氟苯基氰为原料经5步反应合成4-氰基-3,5,2′-三氟-4′-(反-4″-正丙基环己基)联苯,经IR、MS、1HNMR数据分析确定了目标化合物结构.     

Synthesis and Thermal Oxidation Stability of Nanocrystalline Niobium Diboride

Inorganic Materials - A method has been developed for the synthesis of nanocrystalline NbB2 powder with an average particle size of 65 nm. The material has been prepared by reacting Nb and...     

对-叔丁基杯[6]芳烃对LLDPE热氧稳定性的影响(英文)

用差示扫描量热仪(DSC)和热失重分析仪(TGA)研究了线性低密度聚乙烯(LLDPE)/对叔丁基杯[6]芳烃共混物的热性能。DSC结果显示,在空气氛围中,纯LLDPE和LLDPE/对叔丁基杯[6]芳烃共混物的热降解温度分别是205℃和250℃。TGA研究表明,对叔丁基杯[6]芳烃使LLDPE的热氧化降解温度提高30℃。上述结果说明,对叔丁基杯[6]芳烃能大大提高LLDPE的热性能,这主要是由于对叔丁基杯[6]芳烃能够提供-OH反应性基团,其氢原子具有相当的活性,能够与LLDPE热分解生成的活性游离基反应生成氢过氧化物,而自身生成了较为稳定的游离基,从而终止了游离基链的传递和增长。     

Effect of Cr Substitution on Thermal Stability of Magnetization and Oxidation Resistance of SmFeN Compounds

We investigated the effects of Cr element substitution on thermal stability of magnetic flux and oxidation resistance of SmFeN compounds by X-ray diffraction (XRD), thermogravimetry analysis (TG), and flux aging loss measurement methods. We found that with increases in Cr substitution, the irreversible flux losses of bonded magnets made from these alloys decrease remarkably. When Cr substitution reaches 2 at%, the beneficial effect reaches a maximum; the irreversible flux loss of such bonded magnets exposed to a temperature 170 $^{circ}$C for 2 h is only 4.97%. The oxidation resistance of SmFeN magnetic powders is also notably improved with the increased Cr substitution .      

界面改性对T－300／聚酰亚胺复合材料热氧稳定性的影响

采用电化学法连续处理碳纤维，通过阳极氧化剥除Ｔ－３００碳纤维表面耐热性差的环氧涂层，重新涂覆了几种耐热涂层。研究了在３１６℃条件下，５００小时热氧化对Ｔ－３００／聚酰亚胺复合材料层间剪切强度的影响，并且用ＳＥＭ观察了碳纤维表面处理前后的涂层剥落现象及表面形貌。     

航空润滑油的氧化安定性

用腐蚀和氧化安定性试验研究了航空润滑油的氧化安定性。对国内的酯类航空润滑油及俄罗斯相同等级产品的氧化安定性进行了对比评定。     

Thermal Oxidation of Silicon Carbide Substrates

Thermal oxidation was used to remove the subsurface damage of silicon carbide (SiC) surfaces. The anisotrow of oxidation and the composition of oxide layers on Si and C faces were analyzed. Regular pits were observed on the surface after the removal of the oxide layers, which were detrimental to the growth of high quality epitaxial layers. The thickness and composition of the oxide layers were characterized by Rutherford backscat-tering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS), respectively. Epitaxial growth was performed in a metal organic chemical vapor deposition (MOCVD) system. The substrate surface morphol-ogy after removing the oxide layer and gallium nitride (GaN) epilayer surface were observed by atomic force microscopy (AFM). The results showed that the GaN epilayer grown on the oxidized substrates was superior to that on the unoxidized substrates.     

导电聚苯胺的热稳定性

导电聚苯胺的电导率热稳定性一直是涵待解决的问题。由于这一问题的存在，聚苯胺难以保证经过常见工程塑料加工温度（如PC/ABS的235℃混炼温度）热处理后电导率不发生大幅度减弱甚至变为绝缘体。然而，综观国内外有关聚苯胺热稳定性理论和实验研究的文献十分有限。结合目前国内国际的研究状况，总结和分析了聚苯胺热稳定性的改善，提出了改善聚苯胺热稳定性能的方法，同时也为制备聚苯胺类导电塑料给出了一些创新性建议。     

脂肪族聚酯的热稳定性研究

用热失重(TG)和F lynn方法(等转化率方法)研究了聚丁二酸乙二醇酯(PESu),聚丁二酸丁二醇酯(PBSu),聚丁二酸已二醇酯(PHSu),聚癸二酸己二醇酯(PHSe)的热稳定性。结果表明,这些聚酯的热分解温度和分解活化能均随酯基浓度的降低而升高。该研究可对脂肪族聚酯的分子设计、合成和加工工艺提供参考。     

Comparison of Oxidation and Thermal Shock Performance of Thermal Barrier Coatings

Operating temperatures in gas turbine engines have reached to 1200°C with the latest developments in coating technology. Thermal shock and furnace oxidation tests are widely used to determine thermal barrier coating (TBC) performance and its durability in aircraft applications. This paper presents the results of thermal shock and furnace oxidation tests, carried out with regard to the microstructure and TGO (thermally grown oxide) growth behavior of TBC systems. Isothermal oxidation behavior of TBCs was evaluated through examination of microstructure, formation, and growth behavior of TGO layers at 1200°C for different time periods in furnace oxidation tests. On the other hand, thermal shock behavior of TBC was evaluated through examination of its durability at 1200°C with thermal shock test, which was carried out until the coating failure became visible. The relationship between the TGO growth and oxidation behavior was discussed using furnace oxidation test results.     

Thermal Oxidation of Co/GaAs Structures

The kinetics and mechanism of GaAs oxidation in Co/GaAs structures are studied. The interfacial transition layer is shown to influence Co/GaAs oxidation and to lead to predominant growth of cobalt arsenate. This improves the dielectric properties of the structure compared to the oxidation of free GaAs surfaces. A model for the thermal oxidation of Co/GaAs structures is proposed which takes into account the formation of an interfacial transition layer at the initial stages of oxidation.