Bi_2O_3对堇青石陶瓷的烧结行为、相变和热膨胀性能的影响

采用X射线衍射仪、差热分析仪和热膨胀仪等手段研究了由氧化物粉末 (MgO、Al2 O3 和SiO2 )制备堇青石陶瓷时 ,添加Bi2 O3 对堇青石陶瓷相变和性能的影响 ,分析了Bi2 O3 在烧结过程中的作用机理是低温产生液相促进烧结。试验表明 ,Bi2 O3 能明显降低烧结温度 ,在 12 5 0℃烧成 3h后的陶瓷是由α堇青石和少量的 μ堇青石组成。随着Bi2 O3 含量增加 ,陶瓷的致密度和热膨胀系数逐渐升高。Bi2 O3 的添加量 (质量分数 )为 0 .0 4 ,原料相石英消失。Bi-O膨胀系数较Si-O的大和Bi3 + 离子进入堇青石晶格中是引起堇青石陶瓷热膨胀系数升高的主要原因。     

Bi2O3对堇青石陶瓷的相组成、微观结构和性能的影响

采用X射线衍射、扫描电镜、差热分析和热膨胀仪等手段研究了由氧化物粉末(MgO，Ai2O3和SiO2)制备堇青石陶瓷时，添加Bi2O3对堇青石陶瓷相变、相组成和性能的影响，Bi2O3在烧结过程中的作用机理是低温产生液相促进烧结。试验表明，在1350℃烧结3h，该陶瓷由堇青石和孤立分布的玻璃相组成。随Bi2O3含量增加，陶瓷的致密度、弯曲强度和热膨胀系数逐渐升高。Bi2O3的添加量(质量分数)大于4％时，原料相石英消失。硅氧网络骨架结合力减小和一定量的玻璃相是引起堇青石陶瓷热膨胀系数升高的主要原因。     

Bi2O3对堇青石陶瓷的烧结行为、相变和热膨胀性能的影响

采用X射线衍射仪、差热分析仪和热膨胀仪等手段研究了由氧化物粉末(MgO、Al2O3和SiO2)制备堇青石陶瓷时，添加Bi2O3对堇青石陶瓷相变和性能的影响，分析了Bi2O3在饶结过程中的作用机理是低温产生液相促进烧结。试验表明，Bi2O3能明显降低饶结温度，在1250℃烧成3h后的陶瓷是由α堇青石和少量的μ堇青石组成。随着Bi2O3含量增加，陶瓷的致密度和热膨胀系数逐渐升高。Bi2O3的添加量(质量分数)为0．04，原料相石英消失。Bi—O膨胀系数较Si—O的大和Bi^3 离子进入堇青石晶格中是引起堇青石陶瓷热膨胀系数升高的主要原因。     

晶化处理对堇青石微晶玻璃晶相及其性能影响的研究

以堇青石的理论化学组成为基础玻璃配方,采用熔融法制备堇青石微晶玻璃。利用DSC-TG、XRD、SEM研究堇青石微晶玻璃的析晶特性和微观形貌,并对其热膨胀性能以及烧结性能进行测试。结果表明:微晶玻璃初晶相为亚稳MgAl_2Si_3O_(10)相,终晶相为α-堇青石相,随着热处理温度升高,亚稳MgAl_2Si_3O_(10)相向α-堇青石相转变。在1000～1200℃的温度范围内,堇青石微晶玻璃的结构和性能较为稳定。     

烧结助剂对堇青石-莫来石复相陶瓷的致密化和烧结特性的影响（英文）

以高岭土、滑石、工业氧化铝为原料,加入不同含量的B_2O_3、Nd_2O_3、Y_2O_3烧结助剂,通过原位反应烧结法合成了堇青石-莫来石复相陶瓷,研究了烧结助剂对其致密度和烧结特性的影响。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和能谱仪(EDS)表征试样的晶相组成和微观结构。利用FactSage 6.0软件对系统的相组成和液含率进行了模拟对比分析。结果表明:B_2O_3具有最好的助烧结性。添加2.0%B_2O_3的复相陶瓷样品的烧结温度降低,致密度和机械强度提高,其经1 420℃烧成后吸水率和抗折强度分别为0.03%和116.70 MPa。经XRD分析和FactSage模拟证实,由于B_2O_3的液相烧结作用,物质间的固相扩散转变为液相扩散,促进了样品中四方堇青石的生成(未添加B_2O_3样品相组成为六方堇青石)。SEM和EDS结果表明,2.0%B_2O_3促进了晶体的生长与发育,四方柱状或块状堇青石与针棒状莫来石相互交织穿插排列,赋予样品较高的致密度和强度。     

碳铬渣合成堇青石的反应机理及结构表征

以高碳铬铁合金渣、工业氧化铝粉和硅微粉为主要原料,通过高温固相法合成制备堇青石。利用X射线衍射和扫描电子显微镜等研究了烧成温度、保温时间对堇青石材料结晶度、晶粒尺寸、晶相组成和显微结构的影响规律。结果表明:样品中堇青石主要由镁橄榄石进一步反应生成,其最佳烧结制度为1 350℃,保温3 h,堇青石含量在87%左右;随着烧结温度和保温时间升高,样品相对结晶度降低,堇青石晶粒尺寸则逐渐增加,晶胞参数沿a轴晶向轴方向增大,c轴方向减小,晶胞体积变大。铬元素固溶进堇青石晶格是使其晶胞参数变化的主要原因。     

高能球磨作用对合成堇青石基陶瓷的相组成和相变机理的影响

采用XRD分析研究了由分析纯的氧化物粉末制备堇青石基陶瓷时,高能球磨作用及热处理温度对堇青石陶瓷相组成和相变过程的影响,并分析了高能球磨在堇青石陶瓷烧成过程中的作用.结果表明经高能球磨处理的试样在低温烧成(900℃)时,首先出现中间相镁铝尖晶石(MgAl2O4),但1100℃时中间相又消失;与未球磨的试样比较,高能球磨不仅能够降低堇青石的相变温度,而且可大大加快中间相和原料相向α-堇青石转变的速度;同时发现提高烧成温度有利于中间相向堇青石的转变.此外,还研究了粉末的状态(即是否经成型处理)对堇青石陶瓷相组成的影响.结果表明,加压成型使Si4+、Mg2+和Al3+易于扩散,能促进早期的固相烧结和后期的液相烧结,有利于主晶相α-堇青石的合成,但对相组成没有太大影响.     

碳化硅/堇青石复相多孔陶瓷的制备及性能研究

采用碳化硅、烧高岭土、氢氧化铝、滑石为主要原料,石墨为造孔剂制备了碳化硅/堇青石复相多孔陶瓷.研究了烧结温度和烧结助剂二氧化铈对碳化硅/堇青石复相多孔陶瓷气孔率和强度的影响,并分别用XRD和SEM分析晶相组成和断面显微结构表明:制备出的SiC多孔陶瓷的主相是SiC,结合相是堇青石与方石英,多孔陶瓷具有相互连通的开孔结构;在1350℃烧结,并保温3h,当造孔剂含量为15％时,碳化硅/堇青石复合多孔陶瓷性能最佳,其气孔率31.80％,相应的弯曲强度为63.74 MPa.在1200℃下,添加不同含量的CeO2,对烧结样品的相组成有影响,能够降低生成堇青石的温度,在CeO2含量为3％的样品中,堇青石的峰最明显,但是过量的氧化铈会抑制了堇青石的生成;随着CeO2加入量的增加,其气孔率和弯曲强度也会随之变化,1200℃下,在CeO2加入量为4％时其弯曲强度最优.但随着CeO2的含量的增加,其气孔率逐渐下降.     

锂辉石与氧化锆对堇青石陶瓷热膨胀率的影响

以粘土、滑石、氧化铝等为原料 ,压制成型后于 1 3 70～ 1 40 0℃烧成 ,合成了堇青石陶瓷。研究了外加 5 %～ 1 0 %的β 锂辉石或氧化锆对堇青石陶瓷热膨胀率的影响。结果表明 ,这两种添加剂均能降低堇青石陶瓷的热膨胀率。XRD分析表明 ,添加锂辉石或氧化锆的堇青石试样中分别形成了莫来石和锆英石晶体     

碳化硅-堇青石多孔陶瓷的制备及其性能

以碳化硅粉末、高岭土和滑石等为原料,按堇青石的化学计量比设计原料配比,制备了堇青石理论生成量分别为0、10%、15%、20%、100%的碳化硅-堇青石多孔陶瓷,测定了试样的抗折强度、显气孔率和热膨胀系数,并分别用XRD和SEM分析了试样的晶相组成和断面形貌。结果表明:与碳化硅多孔陶瓷相比,碳化硅-堇青石多孔陶瓷的抗折强度显著提高,热膨胀系数明显降低,但显气孔率有所降低。SEM分析结果表明:碳化硅-堇青石多孔陶瓷中碳化硅颗粒排列较紧密,断面呈“网格状”结构;而在多孔碳化硅陶瓷中,晶粒形貌清晰且排列较疏松,气孔平均孔径较大。     

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。