共查询到19条相似文献,搜索用时 93 毫秒
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汽车尾气净化器用蜂窝陶瓷载体对材料的抗热冲击性能要求很高,要求材料具有特别低的热膨胀系数。本文通过对堇青石陶瓷的平均热膨胀系数及微观热膨胀系数的分析,研究了堇青石蜂窝陶瓷的热膨胀特性。 相似文献
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酸处理对堇青石质蜂窝陶瓷性能的影响 总被引:1,自引:0,他引:1
用硝酸溶液对堇青石质蜂窝陶瓷样品进行处理。测定了酸处理时间不同的样品的热膨胀系数、气孔率和吸水率及抗压强度,研究了酸处理对堇青石质蜂窝陶瓷性能的影响规律,通过SEM分析了酸处理前后样品的断面形貌.并用ICP测定了酸处理液中的各种离子浓度,探讨了酸处理影响性能的机理。试验结果表明:酸处理能显著降低堇青石质蜂窝陶瓷的热膨胀系数,增加显气孔率和吸水率,但削弱了材料的机械强度。 相似文献
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采用溶胶-凝胶法制备了化学组成为CaZr4P6O24(CZP)的溶胶态前驱物,用其涂覆薄壁蜂窝堇青石陶瓷,经过700℃焙烧2h转化为具有低热膨胀特性的结晶态CZP涂层。用X射线衍射和BET(Brunauer-Emmett-Teller)氮吸附法表征了涂层的物相和孔结构,用扫描电镜观察了涂层表面及涂层与基体的界面结合处的形貌,用能量色散光谱仪分析了涂层中的元素分布及含量。结果表明:在蜂窝堇青石陶瓷基体上形成的涂层组成为CZP;表面沉积了19.5%(质量分数)CZP的蜂窝堇青石陶瓷的BET比表面积、孔体积和平均孔径分别为16.4m2/g,0.0225mL/g和2.74nm。CZP涂层与蜂窝堇青石基体的界面结合良好。发动机台架性能试验结果表明:"CZP-蜂窝堇青石"复合载体负载的单钯催化剂表现出与"γ-Al2O3-蜂窝堇青石"负载的单钯催化剂相近的三效转化活性。 相似文献
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堇青石峰窝状结构填料的制备和应用 总被引:1,自引:0,他引:1
本文研究了利用堇青石为主要原料制备蜂窝状结构填料的工艺过程,重点考察了增塑剂的组成和焙烧温度对填料性能的影响,测试了堇青石的稳定性和峰窝状结构填料的热膨胀系数,工业试验表明:该蜂窝状结构填料是一种有效的气体分布器,可以使催化剂铂的损失减少12.5%. 相似文献
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HIROYUKI IKAWA TADASHI OTAGIRI OSAMU IMAI MASAHARU SUZUKI KAZUYORI URABE SHIGEKAZU UDAGAWA 《Journal of the American Ceramic Society》1986,69(6):492-498
The crystal structure of high cordierite and that of high cordierite solid solutions containing either Mn or Ga or Ge were refined. The structural changes caused by substitutions and the characteristic features of deformations of each T1O4 , T2O4 tetrahedron and MO6 octahedron were clarified. Thorough crystal chemical considerations led to a conclusion that the structure of Mn-bearing solid solution at room temperature may be regarded as a model structure of high cordierite at an elevated temperature. On the basis of the thermal expansion mechanism derived from this consideration, the thermal expansion behavior of the solid solutions is presented. 相似文献
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A novel design for diesel particulate emission filter based on wall structure of pore channels of honeycomb filter is proposed. Our anticipation in this new design is that, if whiskers are coated on walls of the pore channels of honeycomb filter, the trapping efficiency of honeycomb filter will be improved and also the pressure drop will be substantially reduced. In present study, cordierite whiskers were coated on cordierite based honeycomb support (diameter 13 cm, and height 14.5 cm, 600 cells/inch2) by in-situ method. Whisker coating was carried out on walls of the pore channels of cordierite support from aqueous slurry containing a mixture of kaolin, talc, alumina and silica. Coating was performed by wash coat method. Firing was carried out at 1350C for 4 h under flowing air atmosphere. XRD measurements revealed us complete formation of cordierite phase. SEM analysis on the coating showed the formation of three-dimensional network of cordierite whiskers on cordierite support. In order to evaluate the particulates trapping efficiency of the newly developed honeycomb filter, smoke test was carried out with a 2L diesel engine for the both un-coated and coated cordierite honeycomb samples and the results were discussed with respect to their microstructures. 相似文献
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元素掺杂对堇青石晶体结构及热膨胀系数的作用 总被引:7,自引:0,他引:7
堇青石陶瓷在抵抗热震和热膨胀方面具有独特的优点,特别适合用于象汽车尾气净化载体和集成电路基板等对热膨胀要求极为严格的场合,为了进一步降低堇青石陶瓷的热膨胀系数和改善晶体热膨胀的各向异性效应,目前大多采用掺杂元素的方法,如Ga、Ge、Fe和Ca,本文阐述了堇青石晶体的热膨胀机理,按照元素的性质详细叙述了各类元素的掺杂对堇青石的晶格常数格沿α堇青石两个晶轴a、c方向热膨胀系数的影响。 相似文献
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Masaki Katayama Makiko Kato Shingo Kuramochi 《Journal of the American Ceramic Society》2013,96(6):1863-1868
Dense cordierite ceramics were prepared from a sol mixture of alumina, silica, and magnesia, and the relationship between microstructure and thermal expansion was clarified for sinters with relative density greater than 97%. In the dense cordierite ceramics, submicrometer‐sized primary cordierite crystals aligned in the same crystal orientation and constituted the domain structure. We discovered that these domain structures could be easily observed by optical polarizing microscopy and quantified by digital image analysis of the photographs. The occurrence of microcracks between domains larger than 40 μm was induced by the thermal expansion anisotropy of the cordierite crystal axes. As a result, the mean thermal expansion coefficient of the cordierite ceramics decreased to 0.4 × 10?6 K?1 from the average value of the crystal axes of 1.7 × 10?6 K?1. This lower thermal expansion coefficient could be theoretically explained by partial microcracking. 相似文献
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VOCs大多具有毒性,并伴有刺激性的恶臭,直接排放会威胁人类健康,并对环境造成严重污染。目前,催化燃烧技术是工艺较为成熟,同时也是应用较为广泛的VOCs的净化方法。实际过程使用的催化燃烧催化剂多为具有规整结构的蜂窝状催化剂,活性组分通常为Pt、Pd、Ru等贵金属。从整体式催化剂的角度出发,制备了Al_2O_3和TiO_2两种涂层的整体式催化剂用于催化燃烧消除苯的实验,未添加铈锆粉时的活性顺序:Pt/Al_2O_3/堇青石Pt/TiO_2/堇青石;添加铈锆粉后的活性顺序:Pt/CZ-Al_2O_3/堇青石Pt/CZ-TiO_2/堇青石,同时铈锆粉的添加还可以提高催化剂的热稳定性。 相似文献
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Development of a high-temperature combustion catalyst system and prototype catalytic combustor turbine test results 总被引:3,自引:0,他引:3
A new combustion catalyst system for gas turbines composed of high-temperature durable ceramic catalysts made of fine manganese-substituted hexaaluminate particles and noble metal-carrying cordierite honeycomb catalysts has been developed. A 160 kW prototype catalytic combustor turbine rigged with a 220 mm in diameter catalyst system was constructed and tested including a continuous 215-hour operation and repeated sudden stops. The results showed practical combustion performance with ultra-low NOx emissions less than 40 ppm (converted to 0% oxygen) and the feasibility of long term catalyst durability. 相似文献