无铅压电陶瓷铌酸钾钠的常压烧结及其电学性能

用常压烧结方法制备了Na0.5K0.5NbO3(NKN)无铅压电陶瓷.研究了烧结温度与NKN陶瓷的密度、结构以及电学性能的关系.结果表明:NKN陶瓷与KNbO3相似为正交结构,烧结温度超过1 080 ℃时,出现无压电性第二相.在很小的温度范围内(1020～1100 ℃)烧结体密度有显著不同,当烧结温度为1 080 ℃时,NKN陶瓷烧结密度达到最大值(4.22 g/cm3,相对密度为92%).经1 060℃烧结的NKN陶瓷其压电常数最高,达到122 pC/N;Curie温度为409 ℃;矫顽场为9 kV/cm;剩余极化强度为15 μC/cm2.     

新型高性能陶瓷成型法的研究

探讨了一种新的非化学反应直接凝聚固化成型方法。利用高分子电解质分散剂可以制备固体含量高、流动性良好的陶瓷泥浆。这种泥浆注入非多孔性模具后 ,无需生物酶催化反应 ,只需将温度升至70～80℃ ,泥浆便由分散状态转为凝聚状态 ,泥浆即达到固化成型。这种方法具有工艺简单、容易控制的特点 ,并且可以获得高致密、高均匀性的陶瓷成型体。通过对氧化铝 -高分子电解质 -水系统的吸附及流动特性进行的系统的研究 ,提出了覆盖率理论 ,解释了用经典的DLVO理论难以解释的胶体稳定性与温度敏感特性之间的关系     

钛酸盐陶瓷固化放射性废物

研究了钛酸盐陶瓷的晶体结构和性能,通过PCT实验测定了钛酸锶的浸出率.实验结果表明:钛酸盐陶瓷固化体具有较高的密度,浸出率低,化学稳定性高,是固化放射性废物和进行最终地质处置的理想固化体.展望了钛酸盐陶瓷固化放射性废物的前景.     

烧结温度对氧化锆陶瓷磨球性能的影响

利用滚制成型法制备了氧化锆陶瓷磨球,研究了烧结温度对陶瓷球体积密度和耐磨性的影响.结果表明,滚制法成型的陶瓷球坯体在1550℃、保温2 h的烧结条件下得到最佳效果,其体积密度达到5.91 g/cm3,自磨损率为2.6 ×10-6/h.     

有机硅先驱体在陶瓷成型中的应用

本文介绍用有机硅陶瓷先驱体(Organosilane Preceramic Polymer)成型非氧化物陶瓷制品的研究进展。着重介绍为提高先驱体热解陶瓷产率,降低烧结制品收缩率所采取的先驱体分子设计及成型、交联固化、烧成、烧结工艺的研究状况。     

Na0.5K0.44Li0.06Nb0.94Sb0.06O3无铅压电陶瓷的制备与性能研究

采用传统固相烧结法制备Na0.5 K0.44 Li0.06 Nb0.94 Sb0.06 O3无铅压电陶瓷,研究了烧结温度对陶瓷样品微观结构及电学性能的影响.研究结果表明:烧结温度在1020～1100℃范围内,样品均形成了单一的正交相钙钛矿结构,烧结温度对微观形貌和电学性能有较大影响;与纯KNN陶瓷相比,陶瓷的To-t和Tc均向低温方向移动;当烧结温度为1080℃时晶粒发育比较完全,To-t和Tc分别为45℃和345℃,同时表现出优异的电学性能:d33=200 pC/N,kp=0.365,tanδ=4.67％.     

烧结工艺对石英质多孔陶瓷性能的影响

以石英砂为主要原料,采用液相烧结法,经半干压成型制备石英质多孔陶瓷.采用SEM对多孔陶瓷的显微结构进行表征.探讨了烧结温度、保温时间对多孔陶瓷孔隙率及断裂强度的影响.结果表明:随着烧结温度升高,保温时间延长,石英质多孔陶瓷的孔隙率下降、断裂强度不断增大;最佳烧结温度为1250℃,最佳保温时间为30 min.在最佳烧结工艺条件下,制备得到高孔隙率陶瓷,孔结构单一且孔径分布较窄,平均孔径大约为12.41μm.     

玻璃渗透氧化锆全瓷牙科修复材料的制备与性能表征

采用泥浆法和干压法成型多孔氧化锆陶瓷坯体,经玻璃渗透制备了玻璃氧化锆复合材料,研究了陶瓷坯体的成型和渗透,并对渗透复合材料的性能进行了表征. 结果表明,使用泥浆法成型,氧化锆浆料的固相含量可以达到75%(w),预烧结温度降低至1200℃,坯体预烧结过程中坯体的线收缩率小于0.5%,达到"净成型"要求,3 mm的渗透距离可以在15 min内完成,材料弯曲强度为285 MPa. 使用干压法成型,预烧温度1450℃,收缩率较大,2 mm渗透距离需2 h以上,材料弯曲强度达到400 MPa. 两种方法分别适用于泥浆直接成型工艺和CAD/CAM切削加工,所制复合材料可用于牙冠的核心瓷.     

工艺条件对低温烧结90氧化铝陶瓷显微结构及性能的影响

本文使用CaO-MgO-BaO-SiO2-ZrO2作为90氧化铝陶瓷的烧结助剂,在1420℃烧结得到了密度达3.77g/cm3的90氧化铝陶瓷。探讨了氧化铝粉末的活性、原料细度、成型工艺、烧结温度和保温时间等工艺条件对氧化铝陶瓷的烧结密度及其显微结构的影响。结果表明:活性高细度小的氧化铝粉末可显著降低氧化铝陶瓷的烧结温度,提高烧结体的密度;等静压成型与模压成型试样的烧结密度相近,但前者的强度则比后者提高了60~80%;其它工艺条件对氧化铝陶瓷的结构及性能的影响不显著。     

硅酸铝锂组成的玻璃陶瓷强度的提高

根据研究可以得出结论，以硅酸铝锂组成的玻璃陶瓷通过在NaNO3溶液中进行离子交换可以使制品的强度得到提高。该玻璃陶瓷系按照陶瓷生产工艺，利用高浓度悬浮液以泥浆浇注法在多孔模里浇注成型，随后按照规定的热处理制度对坯体进行烧结和冷却。选择了通过离子交换使制品强度得到提高的最佳的温度—时间制度。     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。