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491.
针对高超声速飞行器飞行时翼前缘存在着严重的气动加热问题,为了保证翼前缘的尖锐外形,提出疏导式热防护结构,利用内置高温热管结构为翼前缘提供热防护。采用数值模拟和电弧风洞试验的方法对翼前缘疏导式结构进行了分析,得到翼前缘内置高温热管具有的防热效果。数值模拟结果表明在一定热环境条件下,翼前缘驻点温度下降了304K,尾部最低温度升高了130K,实现了热流从高温区到低温区的疏导,减弱了翼前缘的热载荷,强化了翼前缘的热防护能力。通过电弧风洞试验可以获得相同的热防护结果,并且在一定飞行条件下高温热管可以自适应启动,验证了数值模拟方法的准确性以及翼前缘内置高温热管疏导式热防护结构的可行性。 相似文献
492.
Chun-Shan Wang Rong-Wen Yang Kuo-Run Hsu 《Journal of polymer science. Part A, Polymer chemistry》1998,36(4):645-653
A series of novel perfluorononenyloxy group containing polyarylates were synthesized by a high-temperature solution condensation of 5-(perfluorononenyloxy)-isophthaloyl chloride ( II ) with various aromatic diols in o-dichlorobenzene. All the polyarylates were amorphous and readily soluble in many organic solvents such as o-chlorophenol, o-dichlorobenzene, chloroform, and polar aprotic solvents at room temperature or on heating. Transparent, tough, and flexible films of these polymers could be cast from the o-chlorophenol solutions. The polymers having inherent viscosity of 0.61–1.63 dL/g were obtained in quantitative yields. These polymers were thermally quite stable. The glass transition temperatures of these polyarylates were in the range of 219–242°C by DSC and 224–251°C by DMA, and the 10% weight loss temperatures in nitrogen and air were above 415 and 397°C, respectively. Moreover, these polymers maintained good mechanical properties (G′ ∼ 108 Pa) up to 220°C and had lower moisture absorption than common polyarylates. The dielectric constants of these polymers ranged from 3.23 to 3.75. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 645–653, 1998 相似文献
493.
Yasuo Saegusa Masahiro Horikiri Daisuke Sakai Shigeo Nakamura 《Journal of polymer science. Part A, Polymer chemistry》1998,36(3):429-435
Two fluorine-containing aromatic polybenzothiazoles were synthesized by direct polycondensation of 4,4′-(hexafluoroisopropylidene)dibenzoic acid and tetrafluoroterephthalic acid with 2,5-diamino-1,4-benzenedithiol dihydrochloride using phosphorus pentoxide/methanesulfonic acid or polyphosphoric acid as both condensing agent and solvent. The effect of introduction of fluorine atom on the synthesis and properties of these polymers was discussed in detail. The perfluoroisopropylidene unit-containing polybenzothiazole was amorphous, and showed good solubility in organic solvents, excellent mechanical properties, and high thermal stability. The perfluoro-p-phenylene unit-containing polybenzothiazole was crystalline, and exhibited lyotropic behavior in concentrated sulfuric acid. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36 : 429–435, 1998 相似文献
494.
铝基矿物在钙基固硫过程中的固相反应机理分析 总被引:1,自引:0,他引:1
在高温电阻炉中对高硫煤掺入钙铝基添加剂后进行燃烧试验,分析了不同条件下煤中加入添加剂后固硫效率、固硫灰渣的矿物组成及微观形貌的变化特性;综合采用TG-FTIR-XRD研究了化学纯矿物CaO-A12O3-CaSO4体系中硫酸钙的高温热分解过程及产物组成.结果表明,A12O3的加入通过固相反应来影响钙基固硫效率,A12O3对固硫效率的影响并非呈单一性;低温下生成Ca-Al酸盐矿物削弱了固硫反应,而高温下CaSO4与灰中生成的含Ca、Al类矿物反应形成高温固硫物相硫铝酸钙并抑制其分解则提高了钙基固硫效率. 相似文献
495.
使用具有微弱自身水硬性的转炉钢渣制备了"无熟料"胶凝材料,改变早期水化环境,并通过压汞法和扫描电子显微镜测试了长龄期(10年)后钢渣体系硬化浆体的孔结构和微观形貌,研究了早期高温强碱环境对于钢渣长龄期水化的影响.结果显示:早期高温强碱环境对钢渣体系的后期孔结构产生不利影响;早期高温强碱环境并不影响凝胶产物的种类,产物都... 相似文献
496.
497.
SOI高温器件及其在汽车电子等领域中的应用 总被引:2,自引:0,他引:2
石油钻井,航空航天,汽车等工业领域急需在高温下工作的器件和电路。SOI技术在高温器件和电路方面有着广泛的应用前景。文章简要介绍了SOI技术应用于制造高温器件和电路方面的进展情况。 相似文献
498.
LOU Ping WU Hang-Sheng 《理论物理通讯》2001,(7)
A mean-field spin-density wave (SDW) analysis of pseudogap in the underdoped cuprates is proposed on the dependence of the energy gap which mimics the pseudogap near (π, 0) point at least. It implies that the pseudogap structure near (π, 0) is not sensitive to the long-range order and will survive leading to the pseudogap phenomenon in the underdoped metallic phase. On the other hand, in the long-range ordering antiferromagnetic region, the mean-field SDW theory holds and the pseudogap structure predicated by the theory should be observable experimentallyv. Then one prediction is that the pseudogap would smoothly extrapolate between itinerant antiferromagnetic phase and underdoped metallic phase. 相似文献
499.
压电陶瓷高温极化机理研究 总被引:5,自引:3,他引:2
介绍了压电陶瓷高温极化机理,通过电畴的形成及顺电铁电相变机理对其进行了解释。 相似文献
500.
A. G. Merzhanov 《Russian Chemical Bulletin》1997,46(1):1-27
The review is devoted to the problem of self-propagating high-temperature synthesis (SHS). The fundamentals of SHS are briefly
considered, the most promising results of the experimental diagnostics and modeling of SHS processes are presented, new nonlinear
phenomena and the data of thermodynamic calculations, as well as kinetic and macrokinetic studies are discussed. The main
types of the SHS technology and their application for the preparation of new compounds, materials, and items along with technical
and economical effectiveness are considered. New directions and perspectives of SHS are discussed.
The review was prepared from materials of the author's report in the Session of the Presidium of the Russian Academy of Sciences
in May, 1996. (Translated by E. Batova.)
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 8–32. January, 1997. 相似文献