纳米莫来石的制备及其对氧化铝陶瓷性能的影响

以硝酸铝和硅溶胶为原料,采用溶胶-凝胶法合成了纳米莫来石粉体,进而探讨了纳米莫来石对氧化铝陶瓷烧结性能、抗弯强度以及抗热震性能的影响.结果发现,在1100 ℃煅烧硝酸铝与硅溶胶先驱体时仅有少量Al2O3生成,当将煅烧温度升高到1200 ℃时,获得了单一的莫来石晶相,粉体的平均粒径在50～60 nm之间;在氧化铝中添加2wt%～10wt%的纳米莫来石,可以有效促进陶瓷体的致密烧结,并获得良好的抗弯强度与抗热震性能;纳米莫来石含量为5wt%的陶瓷,在1650 ℃烧结后的抗弯强度为247.49 MPa,经过1200 ℃热震后的抗弯强度为218.52 MPa;当纳米莫来石的添加量超过10wt%时,将降低陶瓷的饱和体积密度,并恶化陶瓷的抗弯强度与抗热震性能.     

Al2O3基泡沫陶瓷的研究

以Al2O3和锆英石为主要原料制备了具较高强度及抗热震性的泡沫陶瓷并进行了性能研究与应用试验。结果表明：当锆英石含量为30%时,材料的抗弯强度最大,达3.84MPa;随锆英石含量的提高,抗热震性能增强;泡沫陶瓷的孔隙率与锆英石含量无关,为80-81%,泡沫陶瓷过滤器能有效滤除铸液中夹杂物。     

CeO2对氧化铝基陶瓷的烧结性、力学性能和抗热震性的影响

通过适当工艺制备出了添加不同含量CeO2(0～2wt%)的氧化铝基陶瓷,研究了CeO2对氧化铝基陶瓷的烧结性、力学性能和抗热震性的影响.实验结果表明:CeO2添加剂可以改善氧化铝基陶瓷的显微结构,有利于材料的致密化,提高力学性能和抗热震性.但不同含量的CeO2对其性能有不同的影响.当CeO2的含量为1.5wt%时,氧化铝基陶瓷的致密度最大,抗弯强度和断裂韧性最高;而当CeO2的含量为1wt%时,抗热震性最佳.抗热震性的提高主要归因于增韧作用,同时气孔率也有影响.     

添加剂对SiC-Al2O3陶瓷过滤器性能的影响

采用有机泡沫浸渍工艺制备泡沫陶瓷过滤器.研究添加剂SiO2微粉和CeO2对碳化硅-氧化铝基泡沫陶瓷过滤器的影响.采用正交实验并对陶瓷进行性能检测,结果表明,SiO2,微粉和CeO2的加入量与烧成温度之间存在最佳配比.采用最佳配方在1 380℃下制得的碳化硅-氧化铝基泡沫陶瓷过滤器常温抗压强度为2.10Mpa,热震稳定性为20次.     

锆英石加入量对莫来石-刚玉材料性能的影响

以板状刚玉、电熔莫来石、Al2O3粉、硅线石和粘土为原料,制备了莫来石-刚玉高温窑具,并研究了锆英石加入量对其力学性能和抗热震性能的影响.试验结果表明,随着锆英石细粉的增加,抗折强度有所下降,抗热震性能有较大改善,当锆英石细粉加入量为12%时,获得较好的热震性能.同时还发现随着烧成温度的升高,试样热震性能出现下降.     

锆刚玉-莫来石质泡沫陶瓷过滤器的研制

以刚玉粉、锆英石粉、SiO2微粉、聚乙烯亚胺(PEI)等为主要原料,以孔数(PPI)为10~15的软质聚氨酯泡沫为载体,采用有机泡沫浸渍法于1400℃6h烧后制备了锆刚玉-莫来石质泡沫陶瓷过滤器,分别研究了聚乙烯亚胺、锆英石和SiO2微粉的加入量对浆料稳定性、过滤器强度和抗热震性的影响。结果表明:当聚乙烯亚胺加入量为0.08%(质量分数,下同),锆英石加入量为20%,SiO2微粉加入量为3%时,采用合适的工艺可制备出气孔率大,强度高,抗热震性好的锆刚玉-莫来石质泡沫陶瓷材料。其具体性能指标为:气孔率83%,耐压强度2.4MPa,抗折强度为1.3MPa,抗热震性达6次。     

稀土掺杂Al2TiO5-TiO2-SiO2多相泡沫陶瓷的制备与性能

用有机先驱体浸渍法制备了CeO2和Er2O3等稀土掺杂的Al2TiO5-TiO2-SiO2多相泡沫陶瓷.研究了CeO2和Er2O3等稀土掺杂对Al2TiO5-TiO2-SiO2多相泡沫陶瓷力学性能的影响.结果表明:CeO2和Er2O3掺杂可以显著增强Al2TiO5-TiO2-SiO2多相泡沫陶瓷的抗弯强度,在1 250℃,以质量分数为0.5?O2 0.5%Er2O3掺杂,陶瓷样品的抗弯强度最佳,达到177.4MPa;在50～1 000 ℃,热膨胀系数为5.2×10-6/℃,显气孔率超过76%.     

电熔锆莫来石对Al_2O_3-Cr_2O_3耐火材料抗热震性能的影响

为研究添加电熔锆莫来石颗粒对Al_2O_3-Cr_2O_3耐火材料抗热震性能的影响,以电熔刚玉、电熔氧化铬、氧化铬绿和煅烧α-Al_2O_3粉等为主要原料,分别添加10%(w)的电熔锆莫来石颗粒和3%(w)的m-ZrO_2微粉,对试样进行水冷法抗热震试验、模拟开停车热震试验(2001 600℃)和常温物理性能检测,并重点研究了电熔锆莫来石颗粒对试样抗热震性能的影响机制。结果表明:添加电熔锆莫来石颗粒和m-ZrO_2微粉没有对烧后试样的常温物理性能和显微结构造成较大影响;添加电熔锆莫来石颗粒可以显著提高Al_2O_3-Cr_2O_3试样抗热震性能,效果与添加m-ZrO_2微粉试样的相同;电熔锆莫来石颗粒在烧成过程中析出的SiO_2相,增强了电熔锆莫来石颗粒与基质的结合程度,引导裂纹向电熔锆莫来石颗粒内部扩展,且电熔锆莫来石的共晶及多裂纹结构对裂纹的扩展起"分裂"和"吸收"等作用,从而使得添加电熔锆莫来石的试样获得优异的抗热震性能。     

用于太阳能储热的粘土结合SiC复相陶瓷结构分析

采用SiC粉、高岭土、苏州土为主要原料制备了太阳能储热用粘土结合SiC复相陶瓷.对烧结样品进行了XRD、SEM、EPMA测试分析,同时测试了样品的抗弯强度和热导率.研究结果表明,在1 400℃烧结温度下保温2 h获得了性能优良的粘土结合SiC复相陶瓷样品,主晶相由SiC、莫来石、刚玉和方石英组成,其抗弯强度为65.5 MPa,热导率为8.9W/(m·K),该复相陶瓷具有优良的抗热震性能,有望应用于太阳能热发电中的储热材料.     

低硅铝锆碳滑板的性能研究

针对传统的以锆莫来石为原料的铝锆碳滑板中SiO2含量较多,在浇铸钙处理钢时侵蚀严重的问题,用部分稳定ZrO2(PSZ)代替锆莫来石原料,加入板状刚玉、活性α-Al2O3、炭黑、Si粉、B4C粉和热固性酚醛树脂,分别在1300℃、1400℃、1500℃烧后制成了低硅铝锆碳滑板,并测定了试样的抗渣性、热膨胀系数、膨胀率和热震后强度损失率。结果表明:低硅铝锆碳滑板的烧成温度以1300~1400℃为宜,在此温度下烧成的试样性能优良,其抗热震性和抗渣性均优于以锆莫来石为原料的传统铝锆碳滑板。     

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.     

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。     

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.