ZrO2增韧Al2O3陶瓷耐磨性的研究

本文对五种不同含量ZrO_2增韧Al_2O_3陶瓷在磨粒磨损条件下的耐磨性进行了试验研究。试验结果表明,ZrO_2增韧Al_2O_3陶瓷的磨损机理不同于金属,它并不是简单的显微切削机理或犁沟机理,其耐磨性与陶瓷的硬度和弹性模量没有单调的依赖关系,而与材料的断裂韧性和抗弯强度呈现比较一致的趋向关系。扫描电镜对摩擦表面和抗弯断口的对比观测表明,ZrO_2增韧Al_2O_3陶瓷磨损破坏机理属于一次性脆性断裂机理。因此,欲提高该陶瓷的耐磨性应当着重于提高陶瓷的韧性和强度。利用ZrO_2的马氏体相变,可望提高陶瓷的韧性和强度,故可望提高Al_2O_3基陶瓷的耐磨性。     

氧化锆增韧氧化铝基陶瓷刀具的制备及其切削性能

以α-Al2O3、Zr O_2、Ce O_2粉体为原料,在1 550℃烧结制备了含有10%(体积分数)、20%、30%的ZrO_2–CeO_2[Ce O_212%(摩尔分数),Zr O_288%]增韧Al2O3陶瓷样品。分析了样品相对密度、硬度、抗弯强度及断裂韧性。结果表明,在1 550℃烧结条件下制备的30%ZrO_2–CeO_2增韧Al2O3陶瓷样品致密度只有97.5%,而在1 600℃烧结时,致密度达到99.6%。在1 550℃烧结时,Zr O_2增韧Al2O3陶瓷材料都残留少量m-Zr O_2,而在1 600℃烧结时,样品中m-Zr O_2完全转化为t-Zr O_2,随着Zr O_2含量增加,材料致密度、硬度及断裂韧性均有所降低,弯曲强度先上升后下降。用Al2O3陶瓷刀具材料高速切削灰铸铁时,发现添加10%ZrO_2–CeO_2增韧Al2O3陶瓷样品的切削性能优于其它材料。在1 550℃烧结制备的10%、20%和30%ZrO_2–CeO_2增韧Al2O3陶瓷样品的主要磨损机理都为磨粒磨损与黏结磨损,而1 600℃烧结制备的30%ZrO_2–CeO_2增韧Al2O3陶瓷样品的主要磨损机理为磨粒磨损。     

晶须含量和取向对Al2O3—SiCw陶瓷刀具材料的增韧特性及切削性能的影响

晶须含量和取向不同将影响到Al_2O_3 SiCw陶瓷刀具材料的力学性能,由此将进一步影响到该刀具材料的切削性能。本文测量了不同晶须含量和不同晶须取向的Al_2O_3-SiCw材料的断裂韧性,分析了晶须含量和晶须取向对该刀具材料增韧效果的影响。试验了不同晶须含量和不同晶须取向的Al_2O_3 SiCw刀具的切削性能。结果表明:晶须含量和取向对刀具材料的磨损和破损有很大的影响。因此在实际应用中应根据刀具损坏方式的不同分别选用不同晶须含量和不同晶须取向的Al_2O_3-SiCw刀具材料。以充分发挥该刀具材料的增韧补强效果。     

Ce-TZP材料形状记忆效应的研究

本文对相变增韧氧化锆陶瓷Ce-TZP材料的形状记忆效应进行了研究。研究结果表明:在张应力作用下,含有10mol％CeO_2的Ce-TZP陶瓷具有形状记忆效应。材料的形状记忆效应,由材料内稳定剂的含量及材料的显微结构所决定。记忆量与材料的变形量和环境的温度有关。本文还在理论上对产生形状记忆的条件及其机理作了初步分析和探讨。     

原位SrO.6Al2O3/Ce-TZP复合材料的显微结构与力学性能

通过在Ce-TZP基体中加入AlOOH和SrCO3制备了原位SrO@6Al2O3棒晶/Ce-TZP复合材料,研究了材料的显微结构和力学性能.结果表明,原位生成的SrO@6Al2O3棒晶在基体中分布均匀,复合材料的力学性能有明显的提高.在相当于Al2O3加入量为30vo1%时,强韧化效果最好.原位棒晶增韧和相变增韧起到协同增韧的作用.     

Ce—TZP陶瓷的压缩应力应变特性

本文采用宏微观相结合的方法,对12mol％Ce-TZP+10wt％Al_2O_3陶瓷材料的压缩应力应变特性进行了研究。通过实验首次发现该材料在室温下应力应变关系的伪弹性行为,证实了在加卸载过程中材料内部发生的可逆马氏体相变机理,并同时讨论了室温下材料内部出现可逆铁弹性畴转的可能性。最后就上述两种机理对静止与扩展裂纹的增韧效应进行了分析,提出了可逆相变条件下的增韧计算公式。     

钢纤维及化学镀镍增强Al2O3—SiO2基陶瓷的研究

本文介绍了采用不锈钢纤维及化学镀镍增韧补强Al_2O_3—SiO_2基陶瓷材料的方法:研究了不锈钢纤维含量及化学镀镍对材料性能的影响;探讨了其强韧化机理。结果表明,不锈钢纤维和化学镀镍均对材料有明显的强韧化效果。     

等离子喷涂制备Al_2O_3-Cr_2O_3复相涂层组织及性能

采用等离子喷涂技术在45钢基体上制备Al_2O_3-Cr_2O_3复相涂层,通过SEM、XRD、万能试验机、硬度仪和磨损试验机等设备测定并分析了涂层组织结构,物相组成,以及涂层结合强度、孔隙率、硬度、磨损率等性能。结果表明:随着Cr_2O_3含量的增加,γ-Al_2O_3亚稳定相的比例逐渐降低,α-Al_2O_3稳定相的比例逐渐提高;复相涂层相比单一涂层,组织更加致密,综合性能更优,并且在40%氧化铬含量时最佳:孔隙率1.1%,结合强度12 MPa,剪切强度23.45 MPa,硬度为1010 HV,磨损率0.34%。     

原位SrO·6Al2O3／Ce—TZP复合材料的显微结构与力学性能

通过在Ce-TZP基体中加入AlOOH和SrCO3 制备了原位SrO·6Al2 O3 棒晶 /Ce -TZP复合材料 ,研究了材料的显微结构和力学性能。结果表明 ,原位生成的SrO·6Al2 O3 棒晶在基体中分布均匀 ,复合材料的力学性能有明显的提高。在相当于Al2 O3 加入量为 3 0vo1 %时 ,强韧化效果最好。原位棒晶增韧和相变增韧起到协同增韧的作用     

添加ZrO2对Al2O—SiC系复相陶瓷力学性能的影响

通过ZrO2强化增韧Al2O3-SiC系陶瓷，其复合材料的力学性能在一定程度上获得改善。ZrO2外加含量在0－40wt%范围内，复相陶瓷的断裂韧性保持上升，而其硬度则呈下降的趋势。少量添加ZrO2(≤10wt%)时，其强度得到提高，当ZrO2含量为10wt%左右，强度达到最大值；超过该含量后强度迅速下降。研究结果表明，复相陶瓷力学性能与瓷体中的二相粒子的相变增韧和热应力共配有关。X射线衍射分析研究表明，随着ZrO2含量增加，材料断口相变量增大，断裂韧性也相应提高，确是ZAS（ZrO2增韧Al2O3-SiC)复相材料中ZrO2(t)→ZrO(m)相变增韧起主要作用。当ZrO2添加含量增加时，二相粒子与基体热膨胀系数不匹配，而在复合材料中产生内应力导致瓷体强度降低，研究还表明10wt%ZrO2增韧Al2O3-SiC陶瓷是一种较佳的高温耐磨材料。     

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。