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利用过氧化氢(H_2O_2)和催化剂二氧化锰(MnO_2)进行化学发泡,基于颗粒稳定泡沫技术,以表面活性剂十二烷基硫酸钠(SDS)为颗粒表面改性剂,用超低固相含量5%~10%(质量分数)的浆料制备了颗粒稳定泡沫。常温常压干燥后在1 430℃烧结2 h制备出闭孔结构的泡沫陶瓷,利用亚微米粉末为原料制备出一种可以与气凝胶相类似的多孔陶瓷材料,其气孔率为98.2%~99.0%。研究了固相含量、H_2O_2和MnO_2加入量对泡沫陶瓷的稳定性影响以及发泡倍率、强度以及孔径与气孔率相互关系。 相似文献
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采用发泡注凝法制备Al_2O_3多孔陶瓷,研究了丙烯酰胺与明胶所组成的二元凝胶体系对陶瓷浆料黏度、发泡效果、坯体强度及陶瓷显微结构的影响,并对烧结陶瓷体的显气孔率、强度等进行了表征。结果表明:丙烯酰胺具有辅助分散作用,可降低明胶对浆料黏度的影响并改善浆料发泡效果;采用二元凝胶体系可制备具有均匀孔径分布的可适当机械加工陶瓷坯体;经1 600℃烧结2 h,可获得显气孔率为70%~90%的Al_2O_3多孔陶瓷,其中显气孔率最高为90.8%的多孔陶瓷其抗压强度高达3.3 MPa。在此基础上,对其进行了表面强化的研究。通过在其表面流延一层高强度多孔薄层,不仅使材料整体抗弯强度从6.4 MPa提高到10.8 MPa,而且可以有效降低高温气流对材料表面的烧蚀程度。 相似文献
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为了降低Al2O3多孔陶瓷制备过程中的干燥后收缩和烧后收缩,提高成品率,将d50分别为25.1、9.4和1.1μm的粗、中、细Al2O3粉体按粗粉中粉细粉质量比分别为50 40 10、10 40 50和100%全细粉的级配方式制备Al2O3泡沫浆料,研究颗粒级配对浆料黏度、干燥生坯的线收缩、烧后试样的线收缩、烧后试样的热导率等性能的影响。结果表明:颗粒级配可以有效提高固含量,且颗粒级配后的发泡浆料在静置30 min后仍能保持稳定,颗粒级配可以明显降低生坯的干燥线收缩以及烧后线收缩,并能降低热导率,提高了发泡法-凝胶注模工艺制备氧化铝多孔陶瓷的成品率。 相似文献
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将海藻酸钠、氧化铝混合制成的浆料定向冷冻,使水定向结冰成孔,再对坯体进行冷冻干燥,使冰升华留下的孔隙结构得以保存,制备具有直通孔结构氧化铝多孔陶瓷。气孔率为66.7%的多孔氧化铝陶瓷具有比传统氧化铝泡沫陶瓷高10倍的渗透率。利用固相体积含量25%的浆料制备的多孔陶瓷抗压强度达到16.03 MPa。通过在原料中加入天然无毒的海藻酸钠作为黏结剂,不仅使整个工艺过程和原料都环境友好,而且使干燥后的坯体具有一定强度,可以满足搬运和机加工的要求。通过控制浆料的黏度和流动性以及分散剂加入量,获得均匀的孔隙结构。此外,还研究了固相含量、烧结温度对气孔率、压缩强度及渗透率等性能的影响。随着固相含量从30%降低到20%,样品的气孔率从61%提高了到72%,而压缩强度从16.03 MPa下降到3.42 MPa,渗透率从0.19×10–11 m2提高到4.51×10–11 m2。随着烧结温度从1 300℃提高到1 500℃,材料的气孔率从69.72%下降到67.02%,而压缩强度从4.45 MPa提高到18.66 MPa,渗透率从4.51×10–11 m2下降到4.09×10–11 m2。 相似文献
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Jin Zhao Chi Yang Shunzo Shimai Xiupeng Guan Guohong Zhou Jian Zhang Juan Liu Shiwei Wang 《Ceramics International》2018,44(1):269-274
Wet foam stability is of prime importance in fabricating porous ceramics with the desired microstructure and mechanical properties. In this research, wet foams were fabricated via direct foaming after separately adding an anionic surfactant (TLS) and a cationic surfactant (DTAC) into alumina slurries with a copolymer of isobutylene and maleic anhydride (PIBM) as both the dispersant and the gelling agent. The foam stability was evaluated by a stability analyzer. The bubble size rapidly increased in the wet foam with TLS as the foam stabilizer and many large bubbles appeared within 60 min. The wet foam containing DTAC was very stable. Cationic DTAC increased the hydrophobicity of alumina particles by interacting with the anionic PIBM adsorbed on the particles. The hydrophobically modified particles acted as the foam stabilizer and enhanced the wet foam stability. Furthermore, the fast gelling speed of the slurry containing DTAC also enhanced the wet foam stability. The average cell size of the ceramic with 82.9% porosity from the wet foam with TLS was 188 µm and the compressive strength was 9.7 MPa. The counterparts from the wet foam with DTAC were 54 µm of average cell size and 18.1 MPa of compressive strength. The superior stability of wet foam brought about a smaller cell size and higher strength of the resultant ceramic. 相似文献
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Xing Du Lei Zhao Xuan He Xin Wang Weimin Qu Hui Chen Huan Chen Junjie Wang Zhongxing Lei 《Journal of Porous Materials》2016,23(2):381-388
Foam instability and long drying cycle limits the widespread use of foaming method. In this paper, a kind of porous mullite ceramic with thermal insulation–mechanical property trade-off were fabricated via novel ultrastable foam and improved gelcasting procedure. The solidification process and stability of foam slurry, as well as the thermal, mechanical property and pore structure of the porous mullite ceramics were investigated. The results showed that porous mullite ceramics with different bulk densities could be prepared via varying volume of foam which was stable enough to be maintained in slurry for a long time. The accelerated gelation rate as well as the gelation degree resulted in the improved gelcasting method led to a shortened period of drying and demould. The obtained pores, which were small, smooth, and unimodal distributed in size in porous mullite ceramics, contributed to achieving the trade-off between thermal insulation and mechanical property. 相似文献
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《Journal of the European Ceramic Society》2020,40(12):4243-4252
The interaction of amino acids (glycine, L-valine, L-isoleucine and L-leucine) with alumina surface was studied to induce partial hydrophobization and production of ultrastable particle-stabilised foams. The evaluation of these amino acids was carried out by mechano-quantum simulations followed by experimental tests (foamability, zeta potential, contact angle and foam lifetime measurements). The experimental results agreed with the trends pointed out by the simulations. The selected amino acids interact with alumina particles in aqueous media and in a broader pH range, leading to hydrophobization of surfaces, which was more intense for amino acids with higher molecular mass (isoleucine and leucine). As a consequence, ultrastable foams with a longer lifetime (> 100 h) were produced and the foam microstructure was preserved from ageing phenomena. Moreover, the attained foams were stable at different pH, opening up new possibilities to develop macroporous multiphasic ceramics, which can result in novel materials for thermal insulation at high temperatures. 相似文献
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Porous alumina-hydroxyapatite (HA) and alumina-tricalcium phosphate (TCP) composites have been fabricated to investigate the effect of HA and ??-TCP addition on protein foaming-consolidation derived porous alumina. HA and ??-TCP loadings along with yolk content, starch content, and sintering temperature were varied to modulate performance of the porous composites. The rheological behavior of slurry shifted from pseudoplastic flow to a Newtonian fluid with increasing yolk concentration. The foaming capacity of slurry increased with yolk addition. The addition of starch into slurry resulted in bigger pore size and avoided the porous bodies from cracks. The shrinkage of sintered bodies increased with increasing HA loading, but decreased with increasing ??-TCP loading. The compressive strength of porous alumina-HA body was found 2.9?MPa at 45.8% porosity and 20.4?MPa at 36.8% porosity. The increasing porosity of porous alumina-TCP body from 56.1 to 61.6% improved the compressive strength from 3.1 to 4.2?MPa. Increasing sintering temperature resulted in large grain size among powder particles, thus improving the compressive strength of porous bodies. Preliminary results of DF-1 cells culture on the surface of porous alumina and alumina-TCP samples are also reported. 相似文献
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Alumina foams with porosity ranging between 50% and 92% were fabricated by foaming followed by coagulation of ovalbumin based aqueous slurries. Different combinations of ovalbumin–water mix and alumina loading provided a means to vary slurry viscosity over a wide range. Slurry viscosity influenced the foaming behavior leading to variation in microstructure and mechanical properties of alumina foams. Controlling the slurry viscosity resulted in controlled the total porosity, microstructures and mechanical properties. Mechanical properties were correlated with different micro-mechanical models. Both microstructure and mechanical properties agreed well as closed cell alumina foam due to presence of low percent area of interconnections. 相似文献
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Urs T. Gonzenbach ré R. Studart David Steinlin Elena Tervoort Ludwig J. Gauckler 《Journal of the American Ceramic Society》2007,90(11):3407-3414
Direct foaming of colloidal suspensions is a simple and versatile approach for the fabrication of macroporous ceramic materials. Wet foams produced by this method can be stabilized by long-chain surfactants or by colloidal particles. In this work, we investigate the processing of particle-stabilized wet foams into crack-free macroporous ceramics. The processing steps are discussed with particular emphasis on the consolidation and drying process of wet foams. Macroporous alumina ceramics prepared using different consolidation and drying methods are compared in terms of their final microstructure, porosity, and compressive strength. Consolidation of the wet foam by particle coagulation before drying resulted in porous alumina with a closed-cell structure, a porosity of 86.5%, an average cell size of 35 μm, and a remarkable compressive strength of 16.3 MPa. On the other hand, wet foams consolidated via gelation of the liquid within the foam lamella led to porous structures with interconnected cells in the size range from 100 to 150 μm. The tailored microstructure and high mechanical strength of the macroporous ceramics can be of interest for the manufacture of bio-scaffolds, thermal insulators, impact absorbers, separation membranes, and light weight ceramics. 相似文献
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Li Zhang Haiting Wang Bin Zheng Huiling Du Anniina Salonen 《Journal of surfactants and detergents》2019,22(5):1237-1245
The demands on foam stability are variable and changing, which is why design of foams that are both ultrastable and stimulable is important. We study foams stabilized using surfactant particles made through precipitation of sodium dodecyl sulfate with alkali chlorides. We have previously shown that depending on the concentrations of surfactant and salt, the foams can be ultrastable or age like common surfactant foams. We now show that the adsorption of surfactant crystals changes with the type of salt added and how the crystals are made, as well as the surfactant concentration. We see differences in foam stability if the crystals are made prior to foaming or if they are formed concomitantly with foaming. The adsorption of the crystals is improved if the crystals are made during generation, possibly because of their smaller size. The foams destabilize when heated above the Krafft boundary. We show that through tuning the surfactant concentration and salt type or concentration, we can modulate the melting temperature, and hence the destruction temperature of foam between 22 and 50 °C. Precipitated surfactant particles are versatile alternatives to stabilize ultrastable and stimulable foams. 相似文献
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Kuttan Prabhakaran Nitin Madhusudan Gokhale Suresh Chandra Sharma Ramji Lal 《Journal of the American Ceramic Society》2005,88(9):2600-2603
A novel process for low-density alumina foams has been studied. Aqueous acidic sucrose solution containing aluminum nitrate when concentrated by heating formed a viscous resin. The resin mixed well with aqueous alumina slurry and the resulting powder-filled resin underwent foaming on heating in a Teflon mold. The green foams produced had very good handling strength. Binder removal and sintering of the green foam prepared at sucrose to alumina weight ratio in the range 0.69–1.03 produced alumina foam bodies with porosities 93.5%–96.7%. Microstructure of the foams depends on sucrose to alumina weight ratio such that a clear transition from reticulated structure to cellular foam structure took place at sucrose to alumina weight ratio below 0.89. Average pore size depends on sucrose to alumina weight ratio and was observed in the range 0.48–2.69 mm. 相似文献
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《Journal of the European Ceramic Society》2014,34(10):2443-2452
Herein an alternative approach was considered for addressing one difficulty of ceramic foams that the foam slurry with a high content of bubbles which were obtained via direct foaming, cannot maintain well for a long time at room temperature. It is fascinating that the foam slurry mentioned above could stably mold and dry at room temperature, based on an animal protein as foaming agent, kaolin, talc powder and alumina as raw materials, alpha-tricalcium phosphate prepared via co-precipitation as curing agent, and hydrophobic activated carbon powders as stabilizing agent. Effects of the calcination temperatures, the contents of alpha-tricalcium phosphate and activated carbon powder on microstructures, crystal phases, compressive strength and open porosities of ceramic foams were studied systematically. The results indicated that ceramic foams with a high open porosity and uniform pore distribution and sizes sought for application in catalysts supports, could be produced by adjusting these parameters. 相似文献
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详细说明了用网状弹性聚氨基甲酸乙脂切片浸渍陶瓷料浆研制AS型泡沫陶瓷过滤器的工艺。采用非磷酸盐添加剂粘合,由碳化硅、氧化铝、硅胶及少量硅酸铝纤维制成的AS型泡沫陶瓷过滤器抗压强度可达1.65MPa而厚度仅为15mm,并且不会造成环境污染,完全可以满足过滤铁熔液的要求。 相似文献