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1.
溶胶—凝胶法制备SiC—AlN复合超细粉末的研究   总被引:2,自引:0,他引:2  
用溶胶-凝胶碳热氮化法在1550-1650℃,50min下制得平均粒径为0.2μm左右的SiC-AlN复合超细粉末,粉末烧结性能良好,在较低合成温度下(1550-1600℃),粉末中出现晶须。本研究还探讨了粉末氮化合成条件对粉末颗粒及物相的影响。  相似文献   

2.
用m-ZrO2和γ-Al2O3超微粉为原料,在四组配料中各加入2%TiO2,第五组配料中未加TiO2。经混合、成型、干燥、1550—1580℃煅烧后,获得了抗热震、耐侵蚀的合成原料。可用作改进连铸用功能耐火材料使用性能的原料。  相似文献   

3.
采用钛酸丁酯和醋酸铅作为原料,通过溶胶-凝胶(Sol-Gel)方法合成了纳米级PbTiO3超细粉末。实验结果表明:采用Sol-Gell方法可以制得纯度为含PbTiO3,99.67wt%,平均粒径为60nm的高纯、超细、粒径分布范围窄的PbTiO3粉末。PbTiO4干凝胶在400℃下热处理2h后,可以得到结晶程度很高的纳米级PbTiO3超细粉末。同时通过对醋酸铅(Pb(Ac)2·3H2O)脱水方法的探讨,得出在190℃下加热数小时可以有效地脱去醋酸铅中的结晶水。  相似文献   

4.
研究了热压法制备的Y2O3稳定的四方ZrO2多晶体(Y-TZP)在单轴压缩试验中的超塑性变形特性。结果表明热压Y-TZP可以超塑性压缩变形至-1.30。讨论了应变速率和温度对超塑性变形的影响。本试验中最佳变形条件为温度1450~1550℃,初始应变速率ε=10-4~10-5S-1。研究了变形前后试样的显微结构的变化。  相似文献   

5.
以NaOH为催化剂,山梨醇与油酸之比为1:1.2,在温度180~190℃、水抽真空的条件下,加热4h合成Span-80。该产品经精制后,产率高,质量好。  相似文献   

6.
对用溶胶-凝胶法制备的莫来石先驱粉末的晶化及烧结行为为进行了研究,先驱粉末在1000℃煅烧1h形成少量尖晶石,在更高的高度由这种尖晶石相及无定形SiO2相形成莫来石,煅烧后的粉末具有很高的活性,在1550℃烧成0.5h,烧结体相对密度达到98.7%,陶瓷显微结构由细小等轴莫来石晶粒构成,随着烧成时间的延长或烧成温度的升高,烧结体中柱状莫来石晶粒变得越来越多。  相似文献   

7.
工艺参数对TiO2碳热还原合成Ti(C,N)粉末的影响   总被引:4,自引:0,他引:4  
本文探讨了TiO2碳热还原法合成Ti(C,N)粉末过程中合成温度,保温时间,N2气流量,C/Ti比值等工艺参数的变化对粉末性状的影响,实验表明,N比C更易于Ti结合,改变工艺对数可调整Ti(C1-xNx)的x值。在1400~1700℃间可获得x值的0.6~0.85的Ti(C1-xNx)粉末。  相似文献   

8.
提出了N-丁基环庚烷-2-酮的合成方法,研究了催化剂、反应时间、温度等因素对产物收率的影响。以四丁基溴化铵为催化剂,在甲苯—氢氧化钾固—液相中进行反应,80~90℃反应4h,收率达84.7%—88.5%。  相似文献   

9.
合成了4-(5-溴-2-噻唑偶氮)邻苯二酚(5-Br-TAPC)显色剂,并用于钛(Ⅳ)显色反应研究。在pH4.4和OP存在下,5-Br-TAPC与钛(Ⅳ)形成2:1的配合物,其最大吸收波长为544nm,对比度(△λ)114nm,摩尔吸光系数ε644为8.61L·mol-1·cm-1,表观稳定常数为4.98×109(25℃,μ0.1),在0μg~14μg钛/25ml范围内遵从比耳定律。该法用于钢样的分析取得了满意的结果。  相似文献   

10.
反-1,4-聚异戊二烯的结晶行为   总被引:1,自引:0,他引:1  
用膨胀计法研究了负载型钛催化合成反-1,4-聚异戊二烯(TPI)的结晶行为,其本体结晶动力学实验数据符合Avrami方程。结晶速率常数k在20~45℃时,随温度升高而减小;Avrami指数n在20~30℃时,接近1,在45℃时,接近2。同时还考察了交联对TPI结晶速度和结晶度的影响,并用DSC观察了交联TPI熔融吸热峰的变化。  相似文献   

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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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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   

15.
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   

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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