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1.
冷冻干燥法制备MgO—ZrO2超细粉末   总被引:15,自引:3,他引:12  
采用冷冻干燥法制得了烧结性能良好的c-ZrO2(10%MgO,以摩尔计)超细粉末,并冷冻干燥工艺进行了探索,粉末的煅烧温度为800℃,成型后试样经1600℃,2h烧成,相对体积密度达到了95%以上,且全部为立方相。  相似文献   

2.
本文采用XRD分析对硼砂和熔块配合料不同温度焙烧的试样进行系统的物相鉴定。确定硼砂在100—400℃变为β—Na2B4O7,500—600℃变为α—Na2B4O7,700℃熔化。而以硼砂19%,长石18%,石英24%,硅灰石11%,锆英粉12%,ZnO10.5%,滑石2%,KNO33.5%为配方的熔块配合料焙烧过程的物相变化大体是:600℃左右Na2B4O7先开始熔化,600℃到900℃滑石、ZnO、硅灰石、长石先后完全熔化,而石英和锆英石分别于700℃和1100℃开始熔化,直到1300℃虽己基本熔化,但仍有少量残存。熔体成分由硼酸盐变成硼硅酸盐,最后变成锆硼硅酸盐熔融体。  相似文献   

3.
以Na2O·mSiO2为原料,用沉淀的方法并经850℃和1350℃热处理6h后,可以分别制得石英相和方石英相的SiO2粉末。经分析表明,其平均粒径分别为1.0μm和1.2μm,粒径分布范围较窄;SiO2纯度≥99Wt%。  相似文献   

4.
研究了不同反应体系组成的乙烷造反然的反应性能,考究了乙烷-氧-水反应体系氧化裂解制乙烯的反应条件。结果表明,在不同反应体系中,以C2H6-O2-H2O氧化裂解制乙烯反应性能最佳,800℃的乙烷转化率为85.1%,乙烯选择性为68.1%,乙烯收率可达58%,C2H6-O2-H2O氧化裂解帛乙烯体系最佳工艺参数;反应温度为850℃,原料气组成为50.5%,C2H6+25.2%O2+24.3%H2O停留  相似文献   

5.
对会ZrO25mol%~25mol%的MgO-ZrO2材料的烧结,显微结构和力学性能进行了研究。与纯MgO材料相比,ZrO2的添加能起到促进烧结和提高材料强度和抗热震性的作用。1780℃烧结试样的显气孔率由16%降至1%.常温抗折强度由56MPa提高到90MPa以上,1400℃高温抗折强度由7.2MPa提高到47MPa以上,热震稳定性也随着ZrO2含量的增加而提高。  相似文献   

6.
用固体超强酸催化合成尿囊素的研究   总被引:6,自引:0,他引:6  
利用正交实验考察了固体超强酸Fe2O3-SO4^2-作催化剂,以乙醛酸水溶液和尿素为原料合成尿囊素的条件。实验表明,反应温度80℃,时间2 ̄4h,较高的乙醛酸浓度,尿素与乙醛酸摩尔比4:1,催化剂用量0.5%,催化剂在500℃下焙烧为较佳合成条件,收率可达45%以上。  相似文献   

7.
高铝质电极孔预制块的生产与使用吉林丰满耐火材料厂许庆和1生产1.1原料选用Al2O380%~90%,Fe2O3<3.0%,CaO<0.8%,吸水率不大于5%,耐火度>1770℃的I级高铝熟料;Al2O360%~70%,Fe2O30~1%,Cao17%...  相似文献   

8.
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   

9.
由陶瓷复合材料的抗热冲击实验,证明添加W(ZrO2)=20%时可使Al2O3复合陶瓷的热震温度达到370℃,如何添加V(SiCw)=20%可使Al2O3复合材料的热震温度达到430℃,使Si3N4复合材料的热震温度达到650℃;如果采用V(SiCw)=20%,同时添加Al2O3,Y2O3等活性剂,由于强化晶界的作用,可使Si3N4复合材料的热震温度达到700~750℃,还对各添加剂使陶瓷材料抗热冲  相似文献   

10.
水法杀虫双单钠盐原粉结晶工序的工艺探讨   总被引:2,自引:0,他引:2  
探讨杀虫双原药有效体含量≥32%,原药中Na2S2O3含量≤4%,结晶pH值为4.0-5.5。在0℃以下,搅拌结晶,可得杀虫双原粉含量92.04%左右,出粉率58.59%、NaCl含量小于5%,Na2S2O3含量小于1.5%。  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   

13.
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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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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