低温常压烧结制备碳化硅-莫来石复相材料

将6H-SiC和α-Al2O3按质量比为7:3混合,添加0～10%的[BaO+TiO2]作为烧结助剂,球磨后的均匀粉体压制成生坯,在1 200℃预氧化1 h后在氢气气氛下常压烧结1h制备SiC-莫来石复相材料。研究了烧成温度和BaO–TiO2含量对该复相材料烧结性能和相组成的影响。结果表明:1500℃下,随着烧结助剂含量的增加,烧结致密性明显提高,当含量(质量分数)达到8%时,获得显气孔率为0.17%的致密复相材料。预氧化时,烧结助剂中的BaO与α-Al2O3及SiC氧化生成的方石英反应,生成钡长石BaAl2Si2O8,烧成过程中,钡长石转化成玻璃相,促进莫来石的生成,同时促进烧结。复相材料主晶相为6H-SiC和莫来石,次相为玻璃相和Al2SiO5。     

钾长石含量对硬质粘土烧结的影响

以硬质粘土粉(w(Al2O3)>38%,粒度为0.002～0.11mm)和钾长石粉(w(K2O Na2O)=13.13%,粒度为0.005～0.11mm)为原料,配制成钾长石粉加入量分别为0、3.76%、5.30%和6.84%的试料(对应的w(K2O Na2O)分别为0.11%、0.6%、0.8%和1.0%),湿磨2h,烘干后以150MPa压力压制成20mm×10mm的试样,然后在1500～1600℃煅烧3h。对煅烧后试样进行了物理性能检测、物相分析和显微结构分析,以研究钾长石含量对粘土烧结的影响。结果表明:钾长石粉加入前后试样的烧结温度分别为1550℃和1500℃;加入钾长石能消除粘土原料煅烧过程中形成的方石英相,使烧成试样中只出现莫来石晶相;加入3.76%～6.84%钾长石粉的试样中莫来石含量达61%～66%,并且莫来石发育较好,呈针状,长度达8μm,直径约0.5μm。     

原位生长莫来石棒晶增强钡长石复合材料的制备

采用固相反应烧结法制备了原位生长莫来石棒晶增强钡长石复合材料,研究了原料体系、烧成温度对试样相组成、致密化和显微结构的影响.结果表明:(1)粘土-碳酸钡-氧化铝体系可以得到原位莫来石棒晶增强钡长石复合材料,而氧化硅-碳酸钡-氧化铝体系则不能;(2)两个原料体系烧成试样的相组成不同影响其致密化程度;(3)原位莫来石棒晶增强钡长石复合材料中莫来石棒晶形成空间网状结构,棒晶长径比随烧成温度升高而降低.     

以粉煤灰和赤泥为原料烧结陶瓷工艺与性能研究

本文研究了在1050 ℃至1200 ℃之间温度对以粉煤灰赤泥为原料烧结陶瓷的物相和烧结性能的影响.结果表明:实验用粉煤灰原料的主要矿相组成为石英(SiO_2)和莫来石(3Al_2O_3·2SiO_2),赤泥原料的主要矿相组成有钙铝黄长石(Ca_2Al_2SiO_7)、石英(SiO_2)、钙铁榴石(Ca_3Fe_2+3(SiO_4)_3)和钙钛榴石(Ca_3TiFeSi_3O_(12));以粉煤灰赤泥为原料的5组不同配比试样在1200 ℃时试样气孔率相对降低,体积密度和抗压强度相对程度增大;其中5#试样在经1200 ℃烧结后的气孔率为1.67%,体积密度为2.10 g·cm~(-3),抗压强度为123.23 MPa,达到较好的烧结致密状态,试样主要物相是钙钠长石和莫来石.试样内莫来石的形成及玻璃液相的增加促进烧结并在1200 ℃达到致密烧结状态.     

白云石质煤矸石的烧结及其熟料的抗水化性

首先分析了某矿区白云石质煤矸石的化学矿物组成,然后研究了该煤矸石(粒度0.1 mm)的烧结(分别在1 500、1 550、1 600、1 650℃保温3 h煅烧)及其烧后熟料颗粒(3~5 mm)的抗水化性,并分析了熟料物相组成和显微结构。结果表明:该矿区白云石质煤矸石在1 600℃3 h煅烧后具有致密的组织结构,试样的显气孔率为0.56%,体积密度达到3.14 g.cm-3,在(0.15±0.01)MPa的蒸汽压力下蒸煮12 h尚未完全水化,而且在空气中放置40 d仍未粉化,具有较好的抗水化性。这主要是由于白云石质煤矸石原料中所含的Al2O3、TiO2、Fe2O3等杂质在烧结过程中反应生成了不易水化的C4AF等低熔物,不仅促进了材料的烧结,而且在游离CaO表面形成保护膜,从而在一定程度上提高了材料的抗水化性。     

低品位煤矸石制备多孔莫来石研究

为了综合利用低品位煤矸石,首先对其原矿进行低温(400℃以下)煅烧和酸洗除杂的预处理,然后以预处理后的煤矸石为主要原料,适量添加氧化铝使n(Al2O3)n(SiO2)=1 1,以平均粒径5.6~6.2μm的交联丙烯酸树脂做造孔剂,PVA溶液为结合剂,经反应烧结制备多孔莫来石,并研究了造孔剂添加量对多孔莫来石显微结构和性能的影响。结果表明:以低品位煤矸石为主要原料,经过低温煅烧和酸处理后,适量添加氧化铝和造孔剂,经1 600℃2 h反应烧结可一步制备出主晶相为莫来石的多孔莫来石;随着造孔剂添加量的增加,多孔莫来石的显气孔率和线收缩率明显增大,体积密度、热导率和耐压强度显著降低,但其质量分数增加到30%后,这些性能的变化趋于平稳。     

工艺条件对高铝粉煤灰制备莫来石性能的影响

以内蒙古中西部地区某电厂煤粉炉高铝粉煤灰为原料,经碱液预脱硅、酸洗除杂活化处理,烧结得到莫来石.研究了不同工艺条件对烧结莫来石产品性能的影响及不同烧结条件下的莫来石产品物相及显微形貌转变规律.实验结果表明,经过预处理后,粉煤灰中的Al2O3含量由47.58wt％提高至65.35wt％,当原料平均粒径为2.89 μm,烧结温度为1600℃,恒温时间为2h时,经预处理后的粉煤灰烧结得到莫来石相含量高、长约10 μm左右的棒状晶体,且理化性能良好,满足相关行业标准要求.     

高强度堇青石-莫来石棚板的研制

以堇青石(1～0.5、0.5～0.2、<0.088 mm)和莫来石熟料(M60,1～0.5 mm)为主要原料,加入25%(w)的由轻烧MgO粉、α-Al2O3微粉及添加剂(紫木节和KOH)组成的混合粉,按堇青石与莫来石的质量比分别为40:35、42.5:32.5和45:30配料、混练、成型后,分别在1 300、1 350和1 400℃均保温3 h条件下烧成,合成出堇青石-莫来石质棚板试样,并检测试样的常温及高温物理性能,同时进行XRD、SEM及EDS分析.结果表明:按m(堇青石):m(莫来石)=45:30配料,在1 350℃ 3 h合成的棚板材料的各项性能指标最好,其主要晶相为堇青石和莫来石,且显微结构均匀,晶间生成大量的原位堇青石和莫来石晶粒,骨料之间的"联接桥"发育良好,材料具有较高的抗折强度.     

添加MgO对不同SiO2含量的ZrO2-Al2O3-SiO2陶瓷烧结的影响

以高纯石英砂、α-Al2O3、ZrO2为原料,MgO为添加剂(添加质量分数分别为0、1%、2%、3%),经研磨、造粒、成型,并在1 600℃烧结2 h后获得了SiO2含量(w)分别为4%、8%、12%的ZrO2-Al2O3-SiO2系陶瓷试样。采用XRD、SEM对试样进行物相和显微结构的分析。结果表明:1)所制备的ZrO2-Al2O3-SiO2陶瓷的主要物相是单斜氧化锆、莫来石和刚玉,随着SiO2含量(w)由4%增加到12%,SiO2与Al2O3反应生成的莫来石量增加,体积膨胀效应越发明显,导致烧结试样的致密度降低;2)添加MgO促进了ZrO2-Al2O3-SiO2陶瓷的烧结,在SiO2含量为4%(w)的陶瓷中加入1%(w)的MgO时,烧结试样的致密度最大,其相对密度达到90.49%,体积密度为3.90 g·cm-3。     

常压烧结制备ZrN(ZrON)-SiAlON复合陶瓷

以粉煤灰(≤74μm)、锆英石(≤44μm)和活性炭为原料,采用碳热还原氮化法在1 550℃保温6 h合成了ZrN-SiAlON复合材料。以加工成的ZrN-SiAlON复合微粉为主原料,加入聚乙烯醇结合剂,分别在1 450、1 500和1 550℃下埋炭粉常压烧结1 h制备ZrN(ZrON)-SiAlON复合陶瓷,研究了烧成温度对复合陶瓷相组成、显微结构和烧结性能的影响。结果表明:1)控制烧成温度可以制备出不同组成的β-SiAlON基复合陶瓷;在1 550℃保温1 h制备的复合陶瓷的主晶相为ZrN、ZrON和β-SiAlON(z=2,Si4Al2O2N6);2)从不同温度烧后试样的微观结构中均能观察到ZrN(ZrON)、β-SiAlON和一种铁硅系化合物存在,且ZrN(ZrON)颗粒均匀地分布于β-SiAlON基质中;3)提高烧成温度会使复合陶瓷的收缩率增大,当烧成温度由1 450℃升至1 550℃时,试样的体积收缩率由19.4%增加至40.3%。     

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。