热处理温度对有机硅树脂结合不烧铝碳滑板性能的影响

以板状刚玉、石墨、Al粉、Si粉和B4C为主要原料,有机硅树脂作结合剂制备了不烧铝碳滑板试样。研究了在空气中先经240℃24h预处理,然后分别于400℃、600℃、800℃、1000℃、1350℃和1450℃保温3h处理后试样的烧结性能、物相组成和显微结构等变化规律。结果表明:热处理温度对有机硅树脂结合不烧铝碳滑板的性能、物相变化和显微结构影响显著。热处理温度为240~600℃时,有机硅树脂裂解产生质量损失,使试样内部结构松散,显气孔率显著增大,常温耐压强度较低;800~1000℃时,试样边缘部分B4C、Al、Si优先氧化,生成须状Al2O3和针状硼酸铝,有利于边缘骨料与基质结构紧密结合,同时,试样内部局部有柱状氮化物生成,相应的体积密度明显增加,显气孔率急剧下降,常温耐压强度达到最高值;温度>1000℃,试样中石墨大量氧化而留下很多气孔,同时Al、Si等氧化反应加剧,试样质量增加和体积膨胀明显,体积密度下降,显气孔率上升,常温耐压强度有下降趋势。     

Al-Si复合Al_2O_3-β-SiAlON-C材料加热过程中性能、相组成和显微结构的变化

以电熔白刚玉(≤0.5、≤0.088和≤0.045 mm)、熔融石英(≤0.5 mm)、鳞片石墨(≤0.15 mm)、矾土基β-SiAlON(≤0.088 mm)、Al粉(≤0.074 mm)和Si粉(≤0.074 mm)为主要原料,以热固性酚醛树脂为结合剂,制成25 mm×25 mm×125 mm的Al-Si复合Al2O3-β-SiAlON-C试样,经200℃固化24 h后,分别在800、1 000、1 200、1 400和1 600℃下埋炭(石墨)保温3 h,冷却后测定其体积密度、显气孔率、常温耐压强度、常温抗折强度、高温抗折强度和抗热震性,并进行XRD和SEM分析.结果表明:1)随着热处理温度的升高,Al-Si复合Al2O3-β-siAlON-C试样的显气孔率均下降,体积密度、常温耐压强度、常温抗折强度、高温抗折强度、热震后残余抗折强度均逐渐提高,但其抗折强度保持率在经1 000℃热处理后最高,随后逐渐降低;2)在高温还原气氛的热处理过程中,试样中的Al、Si与C(CO)或N2反应,原位生成了AlN、β-SiC、Al4C3和β-SiAlON等非氧化物,对试样具有填充气孔及增强增韧的作用.     

采用微孔CA6-MA骨料的Al2O3-CaO-MgO轻质浇注料的性能

以自合成的微孔CA6-MA颗粒(8～5、5～3、3～1 mm)为骨料,以速烧刚玉粉(≤0.074、≤0.043 mm)、α-Al2O3微粉、纯铝酸钙水泥为粉料,经配料、混练、振动成型、养护、烘干后,分别在1 000、1 200、1 400、1 600℃保温3 h热处理,检测热处理后试样的永久线变化、显气孔率、体积密度、常温抗折强度、常温耐压强度、热态抗折强度和热导率,并分析其显微结构。结果表明:1)试样在1 600℃热处理后的永久线变化为1.14%,1 600℃热处理后试样的显气孔率为59.84%,体积密度为1.51 g.cm-3,常温抗折强度为2.7 MPa,常温耐压强度为7.3 MPa,1 400℃的热态抗折强度为1.4 MPa,1 000℃的热导率为0.219 W.m-1.K-1;2)1 600℃热处理后试样基质中有大量片状CA6,骨料和基质之间结合很好。     

Carbores P加入量对硅溶胶结合铁沟浇注料性能的影响

为了获得更加环保的Al2O3-Si C-C铁沟浇注料,在w(电熔棕刚玉颗粒)为60%、w(Si C颗粒和细粉)为21%、w(硅灰)为3%、w(α-Al2O3微粉)为3%、w(白刚玉微粉)为10.5%、w(Si粉)为2.5%的基础配方中,分别以质量分数为0、1%、2%、3%和4%的环保型含碳材料Carbores P等量替代白刚玉微粉,外加质量分数为7%的硅溶胶为结合剂,制成Al2O3-Si C-C浇注料,研究了Carbores P加入量对110℃干燥后及1 100和1 500℃烧后试样显气孔率、体积密度、烧后线变化率、常温耐压强度、常温抗折强度和高温抗折强度的影响。结果表明:随着Carbores P加入量的增加,干燥及烧后试样的显气孔率逐渐增大,干燥后试样的体积密度逐渐减小,1 100℃烧后试样的线膨胀率逐渐增大,干燥后试样的常温抗折强度和常温耐压强度以及1 100和1 500℃烧后试样的常温抗折强度变化均不大;1 100和1 500℃烧后试样的体积密度、1 500℃烧后试样的线膨胀率、1 100和1 500℃烧后试样的常温耐压强度、干燥后试样的高温抗折强度等均呈先增大后减小的变化趋势,均在Carbores P加入量为2%(w)时达到了最大。     

结合剂对Al2O3-MgAl2O4-SiC-C质铁沟浇注料性能的影响

以电熔镁铝尖晶石(粒度为5～3mm、3～1mm)和电熔白刚玉颗粒(粒度<1mm)以及白刚玉细粉、碳化硅细粉、活性αAl2O3微粉、Si粉和球状沥青等为主要原料,在保持基料的配比不变的条件下分别采用铝酸钙水泥(w,3%) SiO2微粉(w,2%)及ρAl2O3(w,4%)为结合剂,振动成型为Al2O3-MgAl2O4-SiC-C试样,室温养护24h后脱模,分别于110℃24h、1100℃3h和1500℃3h(埋炭)条件下热处理,然后测定试样的体积密度、显气孔率、线变化率、抗折强度、耐压强度和抗渣性。试验结果表明:铝酸钙水泥 SiO2微粉结合的浇注料流动性较好,经110℃24h、1100℃3h和1500℃3h(埋炭)热处理后,试样的显气孔率较小,体积密度较大,常温耐压强度和常温抗折强度优于以ρAl2O3为结合剂的;但是,采用铝酸钙水泥 SiO2微粉作结合剂的试样经1500℃埋炭3h处理后的线变化率较大,试样的高温抗折强度和抗侵蚀性能也明显低于ρAl2O3结合试样的。     

添加Si粉-埋碳热处理对刚玉浇注料性能的影响

为了进一步提高刚玉浇注料的高温使用性能,在超低水泥刚玉浇注料中加入不同质量分数(分别为0、4%、6%、8%、10%)的Si粉,经振动浇注成型、养护、烘干后,在埋碳条件下于1 400℃热处理6 h,测定试样的加热永久线变化率及烧后试样的显气孔率、体积密度、常温抗折强度、常温耐压强度以及1 200和1 400℃的热态抗折强度,并对部分热处理后试样进行了XRD和SEM分析。结果表明:1)在刚玉浇注料中引入Si粉,并在埋碳条件下热处理可显著提高浇注料的热态强度。2)埋碳热处理后,试样中不仅形成了非氧化物SiAlON和SiC,而且生成了莫来石,可有效提高浇注料在1 400℃的热态强度。     

蓝晶石对硅溶胶结合Al_2O_3-SiC-C浇注料性能的影响

为了提高Al2O3-Si C-C浇注料在高温使用过程中的体积稳定性,用蓝晶石粉部分替代Al2O3-Si C-C浇注料中的白刚玉粉,研究了蓝晶石加入量(质量分数分别为0、1%、2%、3%、4%、5%和6%)对浇注料经烘干和1 400℃保温3 h热处理后物理性能的影响。结果表明:随着蓝晶石加入量的增加,试样经1 400℃保温3 h热处理后由微收缩逐渐变为微膨胀,体积稳定性以蓝晶石加入量为5%(w)时为最好。经110℃烘24 h后试样的显气孔率、常温耐压强度和常温抗折强度变化都很小,体积密度基本上呈降低趋势;经1 400℃保温3 h热处理后试样的显气孔率基本上呈先升高后降低的变化趋势,体积密度则呈相反的变化趋势,并且均以蓝晶石加入量3%(w)为拐点;常温耐压强度和常温抗折强度略有降低,但降低幅度很小。同一配比的试样,1 400℃保温3 h热处理后的体积密度、显气孔率、常温耐压强度、常温抗折强度均比经110℃烘24 h后的高。XRD、SEM和EDS分析表明,蓝晶石发生了一次莫来石化反应而产生体积膨胀,有效缓解了试样的烧结收缩,使试样具有较好的体积稳定性。     

埋炭气氛下热处理C-Al体系物相和显微结构的演变

为了研究含铝粉的碳复合耐火材料物相和显微结构的变化过程,以-195鳞片石墨和w(Al)=99%的铝粉(≤0.074 mm)为主要原料,按1:1的质量比配料后,加入约占粉料总质量15%的酚醛树脂混合均匀,在液压机上成型。试样经250℃烘干12 h后,分别经800、1 000、1 200、1 400、1 600℃保温3 h埋石墨热处理,用XRD测定烧后试样的物相,并用SEM观察其断口形貌。研究表明:800℃时,铝粉熔融,并和树脂碳在石墨边缘形成粒状Al4C3;1 000℃时,Al4C3增多并发育长大,同时开始出现AlN;1 200℃时,Al4C3发育,呈板状,同时部分氮化成纤维状的AlN;1400℃时,Al4C3生成量减少,氮化或氧化成纤维状的AlN或Al2O3;1 600℃时,Al4C3消失,Al2O3或AlN长大、粗化。     

Al2O3质原料种类和粒度对镁铝碳材料性能的影响

改变镁铝碳材料中Al2O3质原料的种类(分别为特级高铝矾土熟料和电熔刚玉)和粒度(特级高铝矾土熟料的粒度分别为5~3和3~1 mm,电熔刚玉的粒度分别为3~1和≤1 mm),经混练、成型、干燥、固化(180℃保温48 h)、热处理(1 600℃保温3 h)后,检测试样的显气孔率、体积密度、耐压强度、加热永久线变化和抗渣侵蚀性。结果表明:1)当Al2O3质原料种类相同时,Al2O3质原料的粒度越小,镁铝碳试样的加热永久线变化越大,抗渣侵蚀性越差;2)当Al2O3质原料粒度相同时,采用特级高铝矾土熟料的试样的加热永久线变化大于采用电熔刚玉的,抗高碱度渣侵蚀性也差于采用电熔刚玉的。     

电熔白刚玉细粉对RH炉用刚玉质浇注料性能的影响

为进一步提高RH炉用刚玉质浇注料的抗热震性,以烧结刚玉为骨料,烧结刚玉粉、活性氧化铝微粉和铝酸钙水泥(Secar 71)为基质,用电熔白刚玉粉替代基质中烧结刚玉粉,研究了电熔白刚玉加入量对RH炉浇注料1 600℃烧后体积密度、显气孔率、线变化、常温抗折强度、常温耐压强度以及抗热震性能的影响,并用SEM对试样进行显微结构分析。结果表明:随着电熔白刚玉粉加入量的增加,试样的体积密度、热震次数逐渐增加,显气孔率、线变化率逐渐减小,这与试样中生成的六铝酸钙量有关。当电熔白刚玉粉替代量为20%(w)时,试样的抗热震性最好。     

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。