Fe2O3对攀钢高炉钛渣碳氮化过程的影响

采用X射线衍射、扫描电镜以及能谱分析仪、图象分析仪等研究了Fe2O3加入量(质量分数分别为0、4.3%、7.2%、10%)及烧成温度(1000℃、1200℃、1300℃、1450℃)对攀钢高炉钛渣碳氮化过程的影响。结果表明:攀钢高炉钛渣进行碳氮化处理时,先期还原得到的金属铁可以充当Ti(C,N)的生长核心;随烧成温度的升高,附着在金属铁上的Ti(C,N)因金属铁的聚集而团聚长大,Fe2O3外加量增加,上述倾向越明显;当Fe2O3的加入量增加到10%时,在1450℃下保温2h,金属铁与Ti(C,N)的团聚体的平均尺寸可增大3倍以上,达到7.4μm。     

高铝矾土-硅粉氮化合成SiAlON的过程研究

分别以w(Al2O3)为68.08%和45.56%的两种高铝矾土及硅粉为原料,按合成SiAlON的理论配比配料(Si粉过量5%),成型后在流动N2(流量为0.06~0.1m3.h-1)中进行热重分析,同时测定试样在不同温度(900~1500℃)保温6h后的质量变化,并分析氮化后试样的物相变化,从而探讨该试样的氮化过程及其机理。结果表明,高铝矾土-硅粉试样在流动N2中的氮化反应过程可大致分为3个阶段:1)Si粉氮化阶段(900~1200℃),Si粉氮化生成Si3N4和Si2N2O;2)SiAlON形成阶段(1300~1400℃),生成O’-SiAlON和β-SiAlON;3)β-SiAlON的生长发育阶段(1450~1500℃),部分O’-SiAlON转化为β-SiAlON,Al2O3在β-SiAlON中的固溶度增加。     

非水解溶胶-凝胶碳热还原氮化法制备TiN粉体工艺研究

以四氯化钛和异丙醚为原料,二氯甲烷为溶剂,以非水解溶胶-凝胶法制备的Ti O2凝胶为钛源,选用分子量为1300000的聚乙烯吡咯烷酮(PVP)为碳源,采用碳热还原氮化法合成Ti N粉体。通过XRD和FE-SEM研究了PVP用量、合成温度及保温时间、氮气流量对Ti N粉体合成的影响。结果表明,适当增加PVP用量有助于Ti N的合成,但残余游离碳也相应增多;氮气流量一定时,升高合成温度及延长保温时间,有利于Ti N粉体纯度的提高,残余的游离碳变少,晶胞参数接近于标准值;当合成温度为1300℃,保温时间为5 h,氮气流量为40 m L/min时,制备出的Ti N粉体纯度高,晶粒发育良好,形状近似球形,粒径约为0.4μm。     

碳热还原法合成硼化钛

以金红石型TiO2、石墨和B2O3为原料,采用碳热还原法合成了TiB2粉末。借助X射线衍射、扫描电子显微镜和透射电子显微镜等分析手段,研究了工艺条件对合成TiB2的影响。结果表明:合成温度、球磨时间、保温时间、合成气氛是影响TiB2合成的主要因素。随着合成反应温度升高,TiO2的碳热还原顺序依次为:TiO2→Ti4O7→Ti6O11→Ti5O9→Ti3O5→Ti2O3。TiB2的生成反应温度开始于1300℃左右。真空下合成TiB2的最佳工艺条件为:球磨时间为24h,合成温度为1450℃,保温时间为3h。合成TiB2粉末的纯度达到98%,晶粒发育完整,平均粒径为2～3μm。     

原位生成陶瓷相结合Ti(C,N)复合材料及其性能研究

以TiO₂粉、鳞片石墨和Si粉为原料，采用碳热还原氮化法在1 450℃保温2 h制备了陶瓷相结合Ti(C,N)复合材料。研究了Si粉加入量(加入质量分数分别为0、5%、15%、25%)对材料物相组成、显微结构、物理性能及抗氧化性的影响。结果表明：适量Si粉的引入有利于细化Ti(C,N)晶粒，提高Ti(C,N)复合材料的常温力学性能与抗氧化性。当Si粉加入量为5%(w)时，原位生成陶瓷相结合Ti(C,N)复合材料的综合性能较优，其显气孔率、常温抗折强度和常温弹性模量分别约为(38.8±1.6)%、(62.5±2.4)MPa及(59.6±2.2)GPa。随Si粉加入量(w)进一步增加至15%或25%,复合材料的体积密度和力学性能下降。     

硅灰-氮化硅体系材料高温反应的研究

将硅灰(w(SiO2)=94.5%,平均粒度0.08μm)和氮化硅(粒度≤0.074mm)按1:1质量比混合后成型,在空气中埋炭条件下分别经1300℃、1450℃、1500℃、1550℃、1600℃处理3h后水冷,对其显微结构及物相进行了分析。结果表明:在1550℃以上,以硅灰和氮化硅为原料反应生成Si2N2O比较明显,氮化硅颗粒的边角变得圆滑,而且分布在含Si2N2O的连续胶结相中,形成胶结相包裹Si3N4的致密结构;1500℃以下,氮化硅仍然棱角分明,基本上未形成Si2N2O,只是硅灰中的SiO2析晶,析晶比较显著的温度为1300℃。     

碳热还原氮化法制备碳氮化钛粉末

以物质的量比为1∶2.5的TiO_2粉和活性炭粉为原料,于N2气氛下采用碳热还原氮化法在不同的合成温度(分别为1500℃、1600℃、1650℃、1700℃、1750℃,N2压力固定为0.1MPa)和N2压力(分别为0.05MPa、0.1MPa、0.15MPa、0.2MPa,温度1700℃)下保温3h合成了碳氮化钛粉末。研究结果表明提高合成温度和降低N2压力有利于合成碳含量高的碳氮化钛粉末;在N2压力为0.1MPa的条件下,于1700℃保温3h热处理后,可以获得平均粒径为2μm的碳氮化钛粉末。     

热压工艺制备高纯致密Ti3AlC2材料

原料配比为n(TiC)：n(Ti)：n(Al)：n(Si)=2：1：1：0．2的起始混合粉料在1300--1500℃温度下，30MPa压力下热压2h制得高纯致密Ti3AlC2块体材料。添加适量硅作助剂显加快Ti3AlC2的反应合成，使Ti3AlC2在1200℃的温度下大量生成，能谱仪分析表明Si在材料中均匀分布。1300℃和1400℃烧结所得Ti3AlC2颗粒均呈六方板状结晶形貌，其在平面内尺寸大小分别为3～6μm和10～20μm。     

C-Si复合还原氮化合成矾土基β-SiAlON

设计β-SiAlON的z值为3,以68%的生矾土(粒度≤0.074mm,烧后Al2O3含量约68%)、13%的硅粉(粒度≤0.021mm)和19%的炭黑(粒度≤5μm)为原料混合均匀后,装入坩埚中,在氮化炉中分别于1100℃、1200℃、1300℃、1350℃、1400℃、1450℃、1500℃和1550℃氮化处理6h后,测氮化后试样的质量变化率,并借助XRD、SEM及EDS等手段,同时研究了C-Si复合还原氮化合成矾土基β-SiAlON的反应过程。研究结果表明:(1)采用C-Si复合还原氮化的试样,在1100~1200℃时主要是Si与氮气和SiO2反应生成的Si2N2O;1300~1400℃时,C开始参与还原氮化反应,体系中开始有β-SiAlON生成;1450~1550℃时,β-SiAlON量逐渐增多,1500℃达到最大值。(2)与单一采用C、Si的试样相比,采用C-Si复合还原氮化的试样生成的β-SiAlON含量相对高,结晶形貌相对较好。     

碳热还原法合成TiB_2的热力学分析与研究

以30μm TiO2(w(TiO2)>99.8%,金红石型)、50 μm B2O3(w(B2O3)>99.5%)及10μm石墨粉(w(C)>99%)为原料,按n(TiO2):n(B2O3):n(C)=1:1:5进行配料后放入不锈钢球磨罐中抽真空球磨24 h,然后将反应混合物移入石墨坩埚内置于热压炉中,分别在1 250、1 350、1 400、1 500、1 600、1 700℃保温4 h进行反应.对以TiO2、B2O3、石墨粉为原料合成TiB2的反应体系进行了热力学计算,并对反应产物进行XRD与SEM分析.热力学计算表明,上述3种原料通过碳热还原反应合成硼化钛的反应开始温度为1 556 K.而合成产物的XRD分析表明,生成硼化钛的开始温度为1 350℃以上.碳热还原TiO2和B2O3合成TiB2的反应机理应为C还原TiO2,其中间产物为Ti3O5、Ti2O3、TiO,然后这些中间产物与B2O3一起逐渐被C还原生成TiB2.SEM分析表明,TiB2颗粒呈不规则短柱状,粒度为5～10m;当反应温度达到1 700℃以上时,硼化钛晶粒有长大的现象.     

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。