羟基磷灰石的制备、X-ray衍射表征和成型工艺探讨

以沉淀法合成羟基磷灰石（简称HAP）粉末，对生坯进行单向干压成型，设计正交实验，探讨了各主要因素（烧结温度、烧结保温时间和粘结剂）对成型过程的影响。实验结果可知HAP粉末成型的最佳条件为：烧结温度1100℃．烧结保温时间3小时，粘结剂为聚乙烯醇。     

羟基磷灰石-玻璃复合陶瓷的微波烧结

采用沉淀法合成羟基磷灰石粉体,将R2OAl2O3B2O3SiO3体系玻璃粉按一定的比例与HAP粉混合,采用等静压成型和干压法成型2种成型方法对羟基磷灰石玻璃复合粉体成型,分别在1150℃、1200℃、1250℃下微波烧结。利用XRD、IR和SEM等手段对烧结过程中的相变和陶瓷显微结构进行研究,结果表明随着烧结温度的升高,羟基磷灰石玻璃复合陶瓷的结构逐渐致密;烧结温度低于1200℃时主晶相没有发生明显变化,当烧结温度达到1250℃时等静压成型的样品中HAP发生了明显的分解;等静压成型的羟基磷灰石—玻璃复合陶瓷的致密度优于普通干压法成型的陶瓷。     

直接干压成型与真空烧结技术制备Nd:YAG透明陶瓷

以高纯氧化物粉体为原料,采用直接干压成型与固相反应烧结技术制备Nd:YAG透明陶瓷,并对其光学透过率和烧结致密化行为进行了研究。结果表明,经1 760℃烧结10 h后,250 MPa成型压力下的样品透过率最高,在1 064 nm处达到83.8%。其素坯的气孔率为40.5%,气孔平均孔径74.5 nm。烧结后陶瓷的显微结构致密,晶界干净清晰,断裂方式为沿晶断裂。将250 MPa成型压力下获得的陶瓷素坯在不同温度和时间下烧结,得到致密化轨迹、晶粒生长曲线以及显微结构演变等信息。通过理论拟合,得出低温下陶瓷致密化和晶粒生长的控制机制为晶界扩散。     

亚微米高纯透明氧化铝陶瓷材料的制备方法

该技术属于透明氧化铝陶瓷材料制备技术领域。其特征在于它依次含有如下的步骤:用干压加冷等静压的成型工艺把α-Al2O3粉末成型;然后对这些坯体使用无压预烧结:无压预烧结的温度为1200～1350℃,时间为30～480min;把预烧结后的坯体置入热等静压炉中进行后处理,处理温度为1150～1350℃,压力为140～190MPa,保温保压的时间为30～60min,用Ar气作保护气,得到的陶瓷体相对密度大于99.9%;最后对烧结出的陶瓷体进行平面磨制和抛光。它不用加任何添加剂,工艺简单;采用低温烧结,能耗低;尤其是晶粒尺寸小于1μm,故称为亚微米氧化铝陶瓷。因而具有较高…     

氮化硅陶瓷的无压烧结工艺优化及性能研究

以α-Si3 N4为原料,Y2 O3和MgO为复合烧结助剂,通过无压烧结制备出氮化硅陶瓷。为了优化实验配方和工艺参数,采用正交实验研究了成型压力、保压时间、保温时间、烧结温度、烧结助剂含量以及配比对氮化硅陶瓷气孔率和抗弯强度的影响规律。结果表明,影响氮化硅陶瓷气孔率的主要因素是烧结助剂含量和配比,而影响其抗弯强度的主要因素是烧结助剂配比和烧结温度。经分析得出,最佳工艺参数为成型压力16 MPa,保压时间120 s,保温时间2 h,烧结温度1750℃,烧结助剂含量12wt％,烧结助剂配比1∶1;经最佳工艺烧结后的氮化硅陶瓷,相对密度为94．53％,气孔率为1．09％,抗弯强度为410．73 MPa。     

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.     

微波烧结工艺制备纳米羟基磷灰石陶瓷

采用微波烧结法对分别以沉淀法和溶胶凝胶法制备技术的羟基磷灰石(HAP)进行烧结,获得了高强度且晶粒可控的HAP陶瓷。利用X射线衍射、场发射扫描电子显微镜、电子万能材料试验机对样品的相组成、微观形貌和力学性能进行了表征。结果表明:以溶胶凝胶法所制备的HAP粉末为原料的陶瓷材料更容易烧结致密;相比无压烧结,微波烧结能够在保证力学性能的基础上降低烧结温度,控制晶粒生长。当以溶胶凝胶法制备的HAP粉末为原料,压制成型,在微波烧结工艺下烧结制度为1 100℃恒温30 min时,可获得弯曲强度为93 MPa、晶粒大小约为300 nm的高强度HAP陶瓷材料。     

Sr0.5Zr2（PO4）3陶瓷的力学性能研究

用共沉淀法和低分子有机溶剂分散获得SZP粉体，经干压成型和烧结得到SZP陶瓷。研究了其力学性能与烧结温度烧结时间和添加剂用量的关系。最佳工艺条件为：添加Mg06wt%,1300℃或Zn03wt%,1200℃均烧结1．5小时，SZP陶瓷的抗压强度分别可达244．0MPa和226．2MPa。     

成型方式对反应烧结碳化硼基复合材料性能的影响

本文针对干压成型结合冷等静压成型对反应烧结碳化硼基复合材料样品性能的影响进行研究.考察了成型压力、保压时间、加压方式对压坯密度和强度的影响.结果表明:采用100 MPa干压2 min,再经过150 MPa冷等静压保压1 min,压坯密度由干压压制时最大密度1.86 g/cm3升高到1.96 g/cm3,压坯强度可达到2.0 MPa.保压时间和加压方式对压坯的密度、强度的影响不大.干压结合冷等静压相对于干压成型,在相同的烧结温度下样品性能有明显的提高,烧结后样品密度为2.44 g/cm3,显微硬度为2394 kg/cm2,三点抗弯强度为241 MPa.     

硅溶胶凝胶工艺成型钛酸铝-莫来石复相陶瓷的研究

利用硅溶胶凝胶化反应实现了钛酸铝-莫来石复相陶瓷的原位凝固成型，研究了钛酸铝在硅溶胶中的分散行为和氯化铵浓度对浆料固化时间的影响规律，从显微结构入手对比分析了不同成型工艺对钛酸铝复相陶瓷强度的影响。结果表明：硅溶胶通过静电排斥和位阻效应显著提高了钛酸铝浆料的分散性。随着氯化铵浓度的提高，浆料的固化时间缩短。硅溶胶凝胶成型试样的烧成强度明显高于干压和凝胶注模成型的试样，其主要原因是由于硅溶胶凝胶成型的试样颗粒分散好、烧结程度高以及在烧成过程中原位形成的细小莫来石对钛酸铝晶粒生长的抑制作用。     

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。