Ce、Nb对Al_(66)Mn_9Ti_(25)金属间化合物形变和断裂行为的影响

本工作研究了微量Ｃｅ、Ｎｂ对Ａｌ６６Ｍｎ９Ｔｉ２５金属间化合物显微组织、微裂纹生成及扩展倾向、维氏硬度、压缩性能、断裂特征、变形亚结构的影响。结果表明，添加微量Ｃｅ有显著的促进晶粒枝晶化和第二相弥散化作用，从而使微裂纹生成和扩展以及沿晶开裂受到一定程度的抑制，因而，压缩强度明显提高，压缩塑性也有改善。微量Ｎｂ的加入，显微组织仍保持等轴状晶粒和粗大第二相，压缩性能未能改善。

Mn-Ce-Nb-O_x/P84 catalytic filters prepared by a novel method for simultaneous removal of particulates and NO

The Mn-Ce-Nb-O_x/P84 catalytic filter for removal of particulates and NO simultaneous was prepared by a novel method(foam coating method). The process parameters including the concentrations of PTFE emulsion, particle size of catalyst and calcination temperature for preparation of catalytic filters were analyzed. In addition, the physical properties and performance for removal of NO(NH_3-SCR) and particulates of Mn-Ce-Nb-O_x/P84 catalytic filter prepared under the optimized parameters, were also systematic studied. Results show that the process parameters had significant influences on stability and performance of catalytic filter, The Mn-Ce-Nb-O_x/P84 catalytic filter prepared by foam coating method under the optimized parameters, has satisfactory physical properties and catalytic performance for removal of NO and particulates at 140-220 ℃. The NO removal efficiency of catalytic filter can reach95.3% at 200 ℃ as the catalyst loading amount is 450 g/m^2, Moreover,the dust removal efficiency of MnGe-Nb-O_x/P84 catalytic filter reaches as high as 99.98%, and the PM2.5 removal efficiency also reaches99.98%. The anti-sulfur performance of Mn-Ce-Nb-O_x catalytic filter is also attractive, after injecting150 ppm SO_2, the NO removal efficiency still retains up to 85%. It is indicated that the foam coating method can not only make a bond of high strength between catalyst and filter, but also make the catalytic filter possessing an excellent and stable performance for removal of NO and particulates.

Modified Ceria-Zirconia Fluorite-Like Catalysts for the Combustion of Methane

For dispersed ceria-zirconia-based solid solutions prepared via the polymerized complex method and annealed at 700 ℃, effects of bulk doping by Ca, Mn, Co, Bi or Nb cations and surface modification by Mn and Pt on their structural features, surface/bulk oxygen reactivity and catalytic activity in methane combustion are considered. With up to 20 mol% doping, a structural type of homogeneous solid solutions of anion-deficient fluorite with disordered anion vacancies is formed. Doping by transition metal cations or Pt increases the mobility and reactivity of the surface/bulk oxygen. A broad variation in specific rates of methane combustion for the studied systems was observed, suggesting structural sensitivity of this reaction. In general, there is no universal relationship between the oxygen mobility, the reactivity and the catalytic activity in methane combustion, which is explained by the factor of specific methane activation on surface active sites. For the Pt-promoted samples, Pt efficiency in methane activation depends on the Pt-support interaction, and the most favorable ones being mixed Pt/MnOx and Pt/NbOx clusters on the surface of the supports that exhibit high lattice oxygen mobilities.

铌、铈、锰掺杂对钛酸钡基陶瓷性能的影响

在钛酸钡中以五氧化二铌、三氧化二铈形式引入铌、铈元素,采用了固相法反应制备Nb、Ce双施主掺杂的微米级钛酸钡基正温度系数(PTC)陶瓷粉;同时研究了加入受主元素Mn对PTC陶瓷材料性能的影响。利用XRD和SEM分析了样品的物相及微观相貌,发现样品结晶完整,颗粒均匀。实验表明,以Ce、Nb、Mn进行掺杂可有效改善材料在室温条件下的PTC性能;当掺入0.2 mol%Nb_2O_5、0.3 mol%Ce_2O_3、0.08 mol%Mn(NO_3)_2时,制出室温电阻率为616Ω·cm、升阻比大于10、居里温度为60℃的PTC热敏陶瓷;并利用制成的PTC材料作为加热源对受控器件进行加热实验。