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本文采用有机先驱物法制备钡铁氧体磁粉,用有机物控制晶核的生长,得到粒度较小,均匀性好的钡铁氧体磁粉;并用Co2+-Sn4+替代钡铁氧体中部分Fe3+离子,对其改性。用XRD、TSM和Mossbauer谱等手段研究钡铁氧体的性能。结果表明:钡铁氧体磁粉为片状晶体;当控制替代量0.8≤X≤1.2时,可得到较好磁性能的磁粉:Hc=61~124kA/m(762~1560Oe),σs=57.9~59.6emu/g。该磁粉适合于高密度垂直磁记录的要求,且Co2+-Sn4+离子主要替代2b,4fv1和12k位置。即磁铅石结构中的S4层 相似文献
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该试验以59Co作为模拟非放射性同位素,在硼酸存在的条件下研究了铁氧体法去除模拟核电厂放射性废水中Co2+离子的各种工艺条件,结果表明铁氧体法可以有效去除模拟核电厂废水中的Co2+离子.当废水中Co2+离-浓度为5 mg/L、硼酸浓度(以硼计)为1 000 mg/L时,最佳工艺条件:反应时间为60 min、Fe2+/Co“物质的量比为20:1、Fe3+/Fe2+物质的量比3:1、反应温度为40℃、pH为11.在此条件下出水Co2+离子浓度约0.5.μg/L,净化因子达到10 000. 相似文献
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六角晶系M型钡铁氧体(BaO·6Fe2O3)是一种应用范围十分广泛的磁性材料.采用离子替代的方法,可以根据不同的应用需要对其各种性能作调整,如今仍然是磁性材料研究的热门之一.本文综述了近年来国内外一元、二元和三元离子替代M型钡铁氧体所取得的研究成果,并指出了离子替代M型钡铁氧体的下一步研究重点. 相似文献
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溶胶-凝胶法制备W型钡铁氧体及结构分析 总被引:1,自引:0,他引:1
以硝酸钡、硝酸钴、硝酸铁、硝酸镧和柠檬酸为原料,采用溶胶-凝胶法合成了W型钡铁氧体BaCo2Fe16O27和Ba 1-xLaxCo2Fe16O27.通过热重/同步差热分析(TG/SDTA)、X射线衍射分析(XRD)和红外光谱分析(IR)对产物进行了表征,研究了焙烧温度和稀土元素镧的掺杂对晶体结构的影响.结果表明:在制备BaCo2Fe16O27时,当焙烧温度达到1 250 ℃时,产物中不再含有M型钡铁氧体BaFe12O19和CoFe2O4,产物为单一的六方晶系BaCo2Fe16O27铁氧体.在稀土元素镧掺杂实验中,由于镧的加入,产物的红外光谱图在500 cm-1和475 cm-1附近产生新的吸收峰,分析表明分别为Fe2+-O,La-O的吸收峰.另外,稀土元素镧的掺杂对晶胞参数也有一定影响. 相似文献
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阐述了国内外纳米钡铁氧体制备技术的研究进展。纳米钡铁氧体在磁性和吸波性能等方面都展现了优异的特性,具有广阔的应用前景。近年来出现了很多纳米钡铁氧体制备新工艺,溶胶-凝胶法因其在控制产品的成分及均匀性方面具有独特的优越性而成为纳米钡铁氧体粉体和薄膜的主要制备方法,但有些新工艺的机理还需深入研究。分析表明纳米钡铁氧体的制备还需进一步完善,并提出纳米钡铁氧体与导电聚合物的复合、纳米钡铁氧体的掺杂及掺杂后与导电聚合物的复合是纳米钡铁氧体制备的研究方向。 相似文献
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采用溶胶-凝胶法制备了尖晶石型铁氧体Co1-xNaxFe2O4的系列样品,通用XRD,SEM对颗粒的结构、形貌进行了分析。结果表明,所合成的样品均为尖晶石型铁氧体;未掺杂样品CoFe2O4的形貌呈立方颗粒状,粒径均匀,边长约为1μm,掺杂后的样品Co0.8Na0.2Fe2O4颗粒为圆球状,尺寸大约在100~200nm,且有明显团聚的现象。通过对亚甲基蓝的降解情况对其光催化活性进行了研究。结果表明,经过A位Na+掺杂的CoFe2-xCrxO4样品,光催化活性明显提高。 相似文献
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镧和铁掺杂纳米TiO_2的制备及其光催化性能 总被引:1,自引:1,他引:1
采用溶胶-凝胶法,制备了TiO2、Fe3+/TiO2、La3+/TiO2、Fe3+-La3+/TiO2光催化剂。考察了焙烧温度、焙烧时间和掺杂离子的种类和用量对催化剂用于紫外光催化降解亚甲基蓝性能的影响。制备纯TiO2、Fe3+/TiO2和La3+/TiO2的适宜焙烧温度分别为673,673和773 K,适宜焙烧时间为120min(TiO2)、180min(La3+/TiO2)。La3+/TiO2中La3+的适宜掺杂量为1.0%,Fe3+/TiO2中Fe3+的适宜掺杂量为0.04%,Fe3+-La3+/TiO2中,当La3+的掺杂量为1.0%时,Fe3+的适宜掺杂量为0.02%,相应的脱色率为99.83%,99.51%,98.73%。当掺杂量适当时,4种催化剂用于紫外光催化降解亚甲基蓝的活性次序为:La3+/TiO2>Fe3+/TiO2>Fe3+-La3+/TiO2>TiO2。根据XRD结果,由谢乐公式估算出所得光催化剂为纳米粒子。 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
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. 相似文献
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Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
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. 相似文献
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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. 相似文献
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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. 相似文献
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中蓝晨光化工研究院有限公司《塑料工业》编辑部 《塑料工业》2009,37(3)
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. 相似文献
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中蓝晨光化工研究院《塑料工业》编辑部 《塑料工业》2007,35(3):1-25,67
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。 相似文献