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1.
以硅藻土为硅质原料,采用动态水热法合成了具有良好片状结构的托贝莫来石,并研究了原料中铝组分及十二烷基硫酸钠(SDS)对产物形貌的影响及其机理。结果表明:在合成温度为200 ℃、时间为6 h、液固比为20 mL/g、SDS添加量为2.4%、搅拌转速为160 r/min条件下,可以合成出片状结构良好的托贝莫来石产物;以纯二氧化硅为硅源作为对比,当硅藻土作为硅源时,硅藻土中的含铝组分是片状托贝莫来石生成的主要因素之一;铝原子可通过对桥联四面体中硅原子的取代阻碍硅氧四面体双链的生成,进而促使晶体向片状的晶形生长;此外,十二烷基硫酸钠作为一种阴离子型表面活性剂,可与托贝莫来石(001)晶面的H—O发生键合,阻碍晶体在(001)晶面的生长,对片状晶形的生长同样具有促进作用。  相似文献   

2.
以山西某地普通粉煤灰为原料,采用动态水热法合成纳米复合托贝莫来石晶须,考察了CaO/SiO2摩尔比、反应温度、液固比、反应时间的影响. 结果表明,以预活化的普通粉煤灰为原料,控制CaO/SiO2摩尔比为1.0、液固比为25 mL/g,在220℃下水热反应10 h,可制备出晶须长/径比大于20的纳米复合托贝莫来石晶须,优化条件下晶须可相互缠绕成中空球形颗粒,纯度达80%以上.  相似文献   

3.
亚熔盐法粉煤灰脱铝渣水热处理后碱含量的影响因素   总被引:1,自引:0,他引:1  
以亚熔盐法处理粉煤灰的脱铝渣为原料,采用动态水热法分解脱碱,研究了不同A/S(Al2O3/SiO2质量比)、C/S(CaO/SiO2质量比)和不同脱铝溶出工艺对硅渣碱含量的影响. 结果表明,随脱铝渣A/S增加,碱含量先降低后升高,脱铝渣A/S为0.11,硅渣Na2O含量降至1.18%,适当的A/S有利于提高硅渣中含铝托贝莫来石的晶化程度;脱铝渣C/S为0.98,硅渣Na2O含量仅有1.31%,随脱铝渣C/S增加,硅渣碱含量增加,C/S过高会降低硅酸钠钙(NaCaHSiO4)的分解率,不利于生成含铝托贝莫来石相;溶出时间和停留时间较长的脱铝渣在脱碱过程中不易生成含铝托贝莫来石.  相似文献   

4.
原位合成莫来石晶须增强氧化铝基陶瓷   总被引:13,自引:1,他引:12  
采用原位反应合成法研制了自生莫来石晶须增强氧化铝基陶瓷材料。研究了莫来石晶须的形成过程、微观形貌、化学成分以及复合材料的显微结构和力学性能。结果表明,添加适量的AlF3可以促进原位反应合成进程和莫来石晶须的生成。莫来石晶须的直径为0.2~1.0μm,长径比为8~30,可以显著提高复合材料的强度、韧性和抗热震性。  相似文献   

5.
以H_2SO_4、(NH_4)_2SO_4为焙烧助剂对粉煤灰进行焙烧-水浸处理,提取粉煤灰中Al组分,其剩余的残渣作为一种二次废弃物保留了大量的非晶态SiO_2组元,以提取铝组分后富含非晶态SiO_2的残渣为原料,首先在Ca、Si摩尔比为0.5、0.67、0.83、1.00、1.16条件下调配CaO–Al_2O_3–SiO_2–H_2O体系凝胶,在探索最佳水热条件制备出铝代托贝莫来石的同时深入研究其形成机制,并对合成的系列1.1 nm铝代托贝莫来石粉体进行表征。结果表明:在水热反应环境(180℃,24 h)下,凝胶不断晶化,随着体系温度升高至240℃,在形成的莫来石晶体结构当中发生了Al对Si的同型取代,伴随着反应温度继续升高,1.1 nm铝代托贝莫来石可进一步转化为加藤石。  相似文献   

6.
通过溶胶─凝胶工艺制备了莫来石前驱体,加入适当矿化剂经高温煅烧合成了高纯、单相莫来石晶须。XRD及SEM分析结果显示:晶须直径为50~100nm,长度为3~8μm,晶须尺寸均匀性好,表面光洁,直晶率高。运用所制备的晶须制备了多孔基板试样,并与普通粒子堆积法烧成样品显微结构与性能进行比较,进而分析了低维晶须材料与普通粒子的堆积成孔方式的异同。在此基础上,对莫来石晶须在其它方面的应用进行了展望。  相似文献   

7.
《陶瓷》2017,(8)
以煤矸石和硫酸铝为原料,硫酸钠为反应介质,采用烧结法制备莫来石晶须。利用XRD、SEM、DSC等测试方法,研究了煅烧温度和保温时间对莫来石晶须的影响。研究结果表明:温度过低时熔融性差不利于莫来石晶须形成;而温度过高时,已合成的莫来石晶须相发生二次分解,均使莫来石产率降低。经过实验,得出最佳条件:1 100℃保温3h时,合成莫来石晶须长为3~4μm、直径为50~100nm。  相似文献   

8.
以无水三氯化铝为铝源、正硅酸乙酯为硅源、无水乙醚为氧供体、选用K_2SO_4-KCl作为熔盐,采用非水解溶胶-凝胶工艺结合熔盐法制备莫来石晶须,借助XRD、SEM和TEM等测试手段研究了在熔盐环境下莫来石干凝胶的物相转变以及熔盐的引入、热处理温度及保温时间对莫来石晶须形貌的影响。结果表明:引入熔盐后,非水解溶胶-凝胶法在850℃即可合成莫来石晶相,且熔盐K_2SO_4-KCl对莫来石晶体的一维生长有显著促进作用;热处理温度过低或过高、保温时间过短或过长均不利于莫来石晶须的制备,900℃保温3 h能制备出产率高、直径在100~150 nm,长径比为20~35、沿[001]方向择优生长的莫来石晶须。  相似文献   

9.
《粘接》2006,27(6):55-55
营口威克斯化学有限公司利用丰富的铁矿资源,采用先进的技术生产出氢氧化镁晶须(M-HOW),具有增强、增韧、阻燃、抑烟、填充等功能,非常适宜用作胶粘剂和密封剂的增强剂、增韧剂、阻燃剂等。氢氧化镁晶须为白色粉束,无毒、无味、无腐蚀,直径0.1~3μm,长度5—100μm,Mg(OH)2含量大于98%,其余为钙、铁、硅、铝、钠、钾等杂质。  相似文献   

10.
采用非水解溶胶-凝胶法合成莫来石晶种,然后将晶种与钼酸锂熔盐混合制备莫来石晶须。借助XRD、FE-SEM、TEM等测试手段研究熔盐用量、热处理时间等工艺参数对制备莫来石晶须的影响,探讨了莫来石晶须的生长机理以及晶须增强钛酸铝陶瓷的力学性能。结果表明:熔盐用量过多或过少,热处理时间过长或过短均不利于莫来石晶须的制备;莫来石晶种与钼酸盐熔盐的质量比为1∶2,热处理时间为6h能够制得产率高、长径比大于50的莫来石晶须;莫来石晶须用于增强钛酸铝陶瓷,可使其抗折强度提高3.15倍。  相似文献   

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12.
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   

13.
14.
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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17.
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   

18.
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   

19.
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   

20.
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   

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