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以安纳托利亚东南部的天然沥青岩为原料制备泡沫炭。所制泡沫炭的平均孔径和密度分别为150μm和800 kg/m3。主要研究了压力、温度、泄压时间及在最高温度时的停留时间对泡沫形成的影响,同时还评价了炭化过程对泡沫结构的影响。主要研究了压力、温度、泄压时间及在最高温度时的停留时间对泡沫炭进行了表征,并进行了密度及抗压强度分析。结果表明,1 323 K炭化后,泡沫炭压缩强度由10 MPa增加到18.7 MPa。沥青的灰分含量(41.76%)对泡沫炭的密度和压缩强度起重要作用。 相似文献
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中间相沥青基泡沫炭的制备、结构及性能 总被引:3,自引:0,他引:3
以萘系中间相沥青为原料,考察了发泡条件、炭化和石墨化工艺对所制泡沫炭结构和性能的影响.结合粘温曲线、TG-DTG热重曲线以及不同发泡条件下泡沫炭的表面形貌分析,其最佳发泡条件为:发泡温度600℃,升温速率5℃/min,发泡压力5MPa.石墨化升温速率越低越有利于泡沫炭石墨微晶的生长及压缩强度的提高,其中以5℃/min升温至2800℃并恒温30min所制泡沫炭的压缩强度达1.38MPa. 相似文献
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中间相沥青基泡沫炭的制备与结构表征 总被引:11,自引:0,他引:11
将石油系中间相沥青利用限定尺寸法发泡后获得了泡沫炭,泡沫炭再经氧化、炭化和石墨化处理获得了具有良好孔结构的泡沫炭.利用SEM和XRD分析了泡沫炭的形态和结构.发现调整发泡模具中的自由空间可以控制泡沫炭的孔径;炭化和石墨化后泡沫炭的孔径减小,孔壁片层取向接近石墨;泡沫炭的孔壁由平直孔壁和“Y”形孔壁结构成,前者内部片层取向优于后者.大孔径泡沫炭的孔壁具有更紧密的内部分子排列,但其微晶尺寸较小. 相似文献
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纳米碳管对泡沫炭的超临界发泡行为及其力学性能的影响机制 总被引:1,自引:0,他引:1
采用超声波?磁力搅拌的方法, 实现了纳米碳管(CNTs)在中间相沥青(MP)中的均匀分散, 并考察了CNTs对泡沫炭的超临界发泡行为及其压缩强度的影响. 研究结果表明: 在超临界发泡过程中, 处于过饱和状态的甲苯将优先在CNTs/MP固-液界面处成核, 进而不断扩散、聚集、膨胀和发泡, 导致泡沫炭孔结构的均一性得以提高; 当在中间相沥青中均匀分散3.5wt%的CNTs后, 所制泡沫炭的压缩强度由3.2MPa提高到4.7MPa, 升高了46.9%; CNTs良好的导热性能降低了基体碳在石墨化过程中的热应力差异, 使得微裂纹的数量减少, 并且其一维纳米结构使得石墨化泡沫炭的孔壁和韧带结构得以增强. 相似文献
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蒙脱土改性炭泡沫复合材料 总被引:1,自引:0,他引:1
以酚醛树脂、BJO-0930酚醛微球为原材料,与适量蒙脱土混合,采用模压成型法制备出酚醛泡沫前驱体,在Ar气保护下进行800℃炭化处理,得到蒙脱土改性闭孔微球型炭泡沫复合材料。探讨蒙脱土对炭泡沫微观结构、压缩强度和热导率的影响。结果表明,蒙脱土改性炭泡沫复合材料的基体相与微球相结合更紧密,孔隙率降低;压缩强度提高到25.54MPa;热导率也明显降低,800℃下的热导率降为0.588W/(m·K)。 相似文献
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Tannin-based rigid foams and derived glasslike carbon foams are new, lightweight, cellular materials, prepared from 95% natural precursors. They are mainly based on bark extracts that are cross-linked with a little of formaldehyde, in the presence of furfuryl alcohol, blowing agent and acid catalyst. Their carbonaceous counterparts are obtained by pyrolysis in inert atmosphere. Various processing and composition parameters were varied, in order to observe the resultant effects on the pore structure, i.e., cell morphology, apparent density, homogeneity, and surface area. Especially, the amounts of foaming agent, strengthener and additives (nanoclay filler) were changed, and the influences of mould diameter and compression stress during foaming were investigated as well. The foams are found to be slightly orthotropic materials whose pore structure is mainly controlled by the amount of blowing agent, leading to an easily tuneable linear cell density that typically ranges from 50 to 250 pores per inch. All the other parameters have much lower influence. 相似文献
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Cristina Saiz-Arroyo José Antonio de Saja José Ignacio Velasco Miguel ángel Rodríguez-Pérez 《Journal of Materials Science》2012,47(15):5680-5692
Polypropylene (PP) foams have become essential items due to their excellent properties. Nevertheless, obtaining net-shaped PP foams with medium relative densities is a complicated issue. In this article, two processes able to produce moulded PP foams in this density range are presented. One of them is based on a modification of the pressure quench foaming method and therefore uses a physical blowing agent (CO2). The second one is the improved compression moulding technique which uses a chemical blowing agent (azodicarbonamide). PP foams with relative densities in the range between 0.25 and 0.6 and cylindrical shape were prepared using these foaming techniques. A common PP grade (instead a highly branched one) was used to obtain the samples, showing, that by combining the appropriate foaming technique, the adequate moulds, suitable blowing agent and proper foaming parameters, net-shaped PP foams with excellent properties can be produced starting from a conventional PP grade. Samples were characterized by analyzing their cellular structure and their mechanical properties. Results have showed that depending on the chosen foaming route isotropic or anisotropic structures with cell sizes ranging from 40 to 350 μm and open cell content in the range between 0 and 65% can be obtained. Moreover, mechanical properties are highly influenced by the production route and chemical composition of the foams. For instance, the stiffer materials at relative densities higher than 0.4 are the ones produced using the chemical blowing agent while at relative densities lower than 0.4 are the ones produced using the physical blowing agent. 相似文献
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Formulation optimization of unreinforced and lignin nanoparticle-reinforced phenolic foams using an analysis of variance approach 总被引:1,自引:0,他引:1
Formulations of unreinforced and lignin nanoparticle-reinforced phenolic foams were optimized using an analysis of variance approach. The variables studied in the formulation of phenolic foams were stirring speed (650–850 rpm) and blowing agent amount (1.5–3.5 wt.%). For lignin nanoparticle-reinforced phenolic foams, the variables were lignin nanoparticle weight fraction (1.5–8.5 wt.%) and blowing agent amount (1.5–3.5 wt.%). The responses measured for both foams were density, compressive modulus, and compressive strength. In addition, the morphology of the foams was observed using scanning electron microscopy (SEM) to determine cell size distributions. The results showed that the variables studied exhibited a strong influence on the responses and the cell size distribution of the foams. Statistical models allowed for prediction of the properties of the foams and for comparison of the properties of unreinforced and lignin nanoparticle-reinforced phenolic foams. The incorporation of lignin nanoparticles in phenolic foams results in a compressive modulus and compressive strength that has up to 128% and 174%, respectively, of the values for unreinforced foams. The amount of blowing agent saved to produce a reinforced foam was up to 31% of the amount necessary to produce an unreinforced foam of the same density. 相似文献
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金属泡沫材料研究进展 总被引:14,自引:2,他引:12
综述了金属泡沫材料的各种制备方法。液相法制备金属泡沫材料包括气体吹入法、固体发泡剂法和固体—气体共晶凝固法、熔模铸造法、渗流铸造法、喷射沉积法以及粉末加压熔化法等制备方法。采用金属粉末烧结法、浆料发泡法等制备工艺可以从固相制备金属泡沫材料。电沉积法以及气相沉积法可用于制备高孔隙率的金属泡沫材料。最后简要总结了金属泡沫材料的应用。 相似文献
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以1-氟-1,1-二氯乙烷(HCFC-141b)作发泡剂,研究了偏氯乙烯(VDC)共聚物颗粒的发泡能力、中空颗粒的泡孔结构及发泡倍率。实验发现,VDC-甲基丙烯酸甲酯(MMA)共聚物的发泡能力较强,而VDC-丙烯腈(AN)共聚物颗粒很难发泡,当引入第三单元苯乙烯(St)后可改善其发泡性能。VDC—AN—St共聚物颗粒的发泡倍率随着发泡剂浓度的增加或发泡温度的提高而先增加后减小,气泡将随着发泡温度的提高而最终全部破裂塌陷。由破泡和扩散造成的发泡剂损失对VDC共聚物颗粒发泡能力的影响已不能忽略。 相似文献
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Flexible foams are prepared using carboxyl-terminated butadiene-acrylonitrile rubber (CTBN), diglycidyl ether of bisphenol A epoxy resin and a chemical blowing agent. Central composite design experiments are conducted to investigate the influences of three independent variables, i.e., the ratio of CTBN to epoxy resin, the amounts of curing agent (dicyandiamide) and blowing agent (azodicarbonamide), on the foam performances. After that, epoxy foams are also characterized for mechanical properties to explore the effects of the aforesaid ratio, accelerator type, starch and foaming methods. SEM analysis is used to evaluate the changes in cell characterizations. 相似文献
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聚甲基丙烯酰亚胺(PMI)泡沫制备及结构表征 总被引:4,自引:0,他引:4
以甲基丙烯酸、甲基丙烯腈和甲基丙烯酰胺为主要单体原料,在适当的发泡剂存在下,以过氧化物为引发剂引发单体共聚,制得甲基丙烯酸-甲基丙烯腈-甲基丙烯酰胺共聚物,并在高温下进行发泡和环化反应,制得聚甲基丙烯酰亚胺(PMI)泡沫,并表征了PMI泡沫的结构. 相似文献
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The production of magnesium integral foam components with a dense shell and a porous core is investigated. High pressure casting methods are used where liquid magnesium mixed with a blowing agent is injected into a permanent steel mould. A compact shell develops due to fast cooling at the walls. Larger cooling times in the core allow the decomposition of the blowing agent and the evolution of a foam structure. The resulting integral foams show a high weight‐specific stiffness combined with high energy absorption capability. For the first time, foam stabilizing without additives is realized. Stabilization is by foaming during solidification with the primary α‐phase particles acting as obstacles slowing down cell wall thinning. 相似文献