钛酸铝陶瓷的性能及其应用

本对钛酸铝陶瓷的结构、热稳定性、微裂纹、低热膨胀性、机械强度及应用进行了综合阐述,并对工艺条件及添加剂对钛酸铝陶瓷性能的影响进行了讨论,给出了改善钛酸铝陶瓷性能的方法和途径,最后提出了钛酸铝陶瓷的研究开发方向。     

钛酸铝陶瓷及其研究现状

本文简述了钛酸铝陶瓷的制备及性能,论述了钛酸铝陶瓷的稳定性、微裂纹、低热膨胀性,讨论了工艺条件及外加剂对钛酸铝材料性能的影响,最后提出了改善钛酸铝陶瓷性能的技术途径。     

钛酸铝陶瓷及其研究新进展

为了总结近年来国内外对钛酸铝陶瓷的最新研究进展,推动钛酸铝的研究,本文综述了钛酸铝陶瓷的易分解和低强度机理,着重介绍了采用添加剂法、复合相法以及新的合成、成形、烧结等工艺改善钛酸铝陶瓷性能方面的研究进展,并对其最新的应用研究进展作出简单的介绍,更在此基础上提出了钛酸铝陶瓷的发展动向。     

添加剂对钛酸铝陶瓷性能影响

钛酸铝陶瓷以其独特的低膨胀和耐高温性能而倍受青睐,但其较低的强度及一定温度范围内的不稳定性制约了该材料的实际应用,采用添加剂方法可以改善材料性能。讨论了添加剂对钛酸铝陶瓷性能影响的机理,重点介绍了不同添加剂对钛酸铝陶瓷性能的影响。最后在总结前人工作的基础上,对添加剂的发展方向作了合理的预测和展望。     

铸铝用钛酸铝陶瓷升液管的研制

介绍了一步法生产钛酸铝陶瓷升液管的配方组成和生产工艺 ,重点讨论了添加剂和烧成温度对钛酸铝陶瓷升液管性能的影响。结果表明 :添加少量的添加剂和采用中—低温烧成技术 ,可以得性能优异的钛酸铝陶瓷升液管     

铸铝用钛酸瓷升液管的研制

介绍了一步法生产钛酸铝陶瓷升液管的配方组成和生产工艺，重点讨论了添加剂和烧成温度对钛酸铝陶瓷升液管性能的影响。结果表明：添加少量的添加剂和采用中一低温烧成技术，可以得性能优异的钛酸铝陶瓷升液管。     

钛酸铝材料性能及合成工艺

钛酸铝陶瓷集低膨胀和高熔点为一体,但强度低且在一定温度范围内易分解。本文综述着重介绍了钛酸铝陶瓷的结构、性能和合成工艺,并提出了钛酸铝陶瓷的研究开发方向。     

石墨钛酸铝复合除气转子的研制

采用石墨与钛酸铝陶瓷保护套管复合制成石墨钛酸铝复合除气转子,进行了陶瓷保护套管用钛酸铝材料的研究,以及复合除气转子中间过度层的研究。利用钛酸铝具有高熔点（1860℃）、低膨胀和低导热等特性制成保护套管,经过对石墨进行表面处理及合适的中间过度层,经适当的复合工艺制成石墨陶瓷复合除气转子。结果表明,这种转子具有很好的抗热震性及优良精练除气效果。已在使用中显示出性能优异,完全满足铝合金铸件精练除气工艺要求。     

钛酸铝陶瓷及其改性研究

钛酸铝陶瓷作为一种重要的抗热震材料,集低热膨胀率和高熔点于一体。本文从钛酸铝陶瓷的结构、性能、常用的添加剂等几个方面,介绍了目前对钛酸铝改性方面的研究以及国内外的研究成果。     

钛酸铝陶瓷升液管的研制

介绍了二步法制备钛酸铝陶瓷升液管的工艺。讨论了添加剂和工艺因素对钛酸铝陶瓷升液管性能的影响。研究结果表明，添加适量的添加荆和采用合理的制备工艺参数，可以制备出性能优良的钛酸铝陶瓷升液管，满足铝合金低压铸造机的使用要求。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.