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以碱金属氢氧化物及其氧化物和SiC等复配得到了高发射率红外辐射粉料,然后与硅橡胶混合配置,再通过空气喷涂法制备得到了高发射率红外辐射涂层。通过力学、热学、红外辐射、隔热试验等对涂层的各项性能进行了表征。结果表明:辐射涂层具有高红外发射率(>0.85),表现出优异的隔热性能。与添加1 mm长的碳纤维制备的涂层相比,3种添加500μm的短切玻璃纤维制备的自研辐射涂层具有更好的力学性能、界面结合强度以及表面状态。综合对比3种自研辐射涂层,其中添加由SiC以及铁、铝、镁的氧化物组成的辐射填料制备的涂层A效果最优,红外发射率高达0.93,拉伸强度达到2.89 MPa,断裂伸长率达到114%,拉伸剪切强度达到1.36 MPa。 相似文献
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最近发展起来的SiC纤维复合涂层,也就是SiC/SiC层与化学气相沉积(CVD)SiC结合形成复合涂层,已能够在高温下提高C/C复合材料的抗氧化性。形成的SiC纤维复合涂层约300μm厚,生产时先将SiC毡覆盖在3D-C/C基体材料上,然后浸渍一种碳粉与硅粉均匀分散的料浆进行化学气要沉积。通过化学气相沉积(CVD)过程,在复合材料上形成致密的涂层。在CO2-H2O-N2组成的混合气体(CO2 9%、N273%、H2O18%),1700℃下进行5h氧化实验,结果发现有SiC毡增强复合涂层比没有SiC毡增强复合材料失重率低。SiC纤维毡复合涂层由双层结构组成,里层是多气孔的SiC/SiC纤维层,外层为致密的SiC涂层。由于SiC/SiC纤维层热膨胀系数介于C/C复合基体材料与CVD-SiC涂层之间,因此,SiC/SiC中间层在复合材料中起了重要作用,从而由于热膨胀系数不同产生的热应力致使涂层开裂降低到最低程度。涂层试样氧化后,采用缓冲冲床(MSP)测试其残余强度。MSP测试结果表明氧化后C/C复合材料强度值呈发散性,从纤维折断面看有z轴方向分布纤维存在。然而,这种方法仅适用于测试小尺寸试样。从这篇论文中,可看出涂层后的C/C复合材料有高的抗氧化性,其氧化后仍能保持高的残余强度。 相似文献
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《玻璃钢/复合材料》2021,(3)
通过化学气相沉积(CVD)SiC涂层来提高SiC_f/SiC复合材料的耐腐蚀性能,本文以CH_3SiCl_3(MTS)为源气体,在反应烧结SiC基体上制备SiC涂层,控制沉积温度、炉压及H_2/MTS摩尔比等工艺参数,通过X射线衍射实验(XRD)得到不同工艺条件下生成的碳化硅涂层的物相组成和结晶度,通过高温水腐蚀实验检测涂层的耐腐蚀性,并利用扫描电子显微镜(SEM)观察腐蚀前后的表面形貌。结果表明:当沉积时间为8 h,沉积温度从1050℃到1250℃,β-SiC涂层表面平整性提高,沉积厚度由12.97μm急剧增加至71.10μm, SiC晶粒尺寸逐渐增大,最终呈金字塔状;碳化硅涂层腐蚀60 d后,表面呈现针状结构,1250℃下沉积的SiC涂层耐腐蚀性能较好;β-SiC涂层的晶粒尺寸随沉积炉压的增大而增大,结晶度随沉积炉压增大而减小,在200 Pa以下,获得的β-SiC晶粒的结晶度最高(81.08%)、晶粒尺寸最小(13.7 nm);随着H_2/MTS摩尔比增加,β-SiC晶粒结晶度迅速下降,当H_2/MTS=6.5时,结晶度最高(95.91%)。 相似文献
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化学气相反应法制备SiC涂层 总被引:16,自引:1,他引:16
采用化学气相反应法,以3种不同工艺在C/C复合材料表面制备了SiC涂层,并检测了其抗氧化性能.以工业用Si和辅助剂SiO2为原料,在高温、惰性环境中反应产生SiO蒸气,将其引入反应室与C/C复合材料在不同温度下进行气相反应,在试样表面生成一层致密的SiC涂层。X射线衍射分析表明:涂层是由β-SiC组成。从试样截面的扫描电镜可知:不同工艺制得的SiC涂层界面过渡带颗粒的微观形貌各异。经最优工艺制备的涂层过渡带很窄,有β-SiC纳米晶须生成,且其抗氧化性能最佳。 相似文献
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Al/ZnS涂层织物的红外发射性能 总被引:2,自引:0,他引:2
以片状Al粉为金属颜料,加入ZnS、Na2SiO4、羧甲基纤维素钠和不同粘合剂制备低红外发射率涂料。将涂料涂覆在铝板上,比较含4种不同粘合剂涂层的发射率,研究粘合剂对涂层红外发射率的影响。将涂料涂覆在织物上,测量涂层的表观形态,分析工艺处方、织物种类等因素对织物涂层发射率的影响。油性聚氨酯粘合剂涂层的发射率最低,随着Al和ZnS含量的增加,织物涂层发射率逐渐降低,且不同织物基质上的涂层红外发射率不同。当使用油性聚氨酯为粘合剂,铝粉质量分数为35%~40%,ZnS质量分数为2%时,涤纶织物涂层发射率为0.69。 相似文献
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低温化学气相沉积SiC涂层显微结构及晶体结构研究 总被引:4,自引:1,他引:4
在CH_3SiCl_3-H_2体系中,采用化学气相沉积法(CVD)在1000~1300℃制备了SiC涂层。研究了SiC涂层的沉积速率和温度之间的关系,发现低温化学气相沉积SiC为动力学控制过程,反应的表观活化能为85~156 kJ/mol。SiC涂层的外观颜色及涂层表面的显微结构随沉积温度变化而呈现规律的变化:当沉积温度<1150℃时,SiC涂层的外观颜色为银白色,涂层表面致密、光滑;当温度≥1150℃时,SiC涂层外观颜色逐渐变暗,涂层表面变得疏松、粗糙。利用XRD分析了不同沉积温度下SiC涂层的晶体结构,随着温度的升高,SiC涂层的结晶由不完整趋向于完整;当沉积温度≥1150℃,SiC涂层的XRD谱图中除了β-SiC外还出现了少量α-SiC。 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