铸钢用泡沫陶瓷过滤器的研制

本文详述了铸钢用泡沫陶瓷过滤器的研制与应用。试验结果表明：铸钢用泡沫陶瓷过滤器性能优良，有去除钢液中非金属夹杂物的作用，可提高铸钢件的机械性能。     

Al2O3基泡沫陶瓷烧结工艺的研究

采用了常压烧结工艺,考察适用于制备细孔径Al2O3基泡沫陶瓷过滤器的最佳烧结温度方法.通过对泡沫陶瓷烧结工艺的研究,得出最佳烧结温度为1 400℃,保温时间为3 h,可得到抗压强度为2.71 MPa的细孔径氧化铝基泡沫陶瓷过滤器.     

矿用柴油机尾气中碳颗粒净化的研究及其进展

为了防治污染,本文介绍了矿用柴油机尾气中碳颗粒的几种净化方法,即机内净化法(柴油磁化、燃用乳化油、柴油中添入添加剂)和机外净化法(采用水洗过滤装置,采用陶瓷滤芯过滤器、泡沫陶瓷过滤器等)。并详细介绍了各种方法的特点及存在的问题,指出了具体的改进措施。     

有色金属铸件在模具中的过滤

有色金属铸造工业中采用陶瓷泡沫过滤器,能减少铸件氧化夹杂,改善性能,是铸造技术的新发展。开放式陶瓷泡沫具有微孔连续网状结构,制成过滤器后也就具有金属流动的曲折通道,从而起到抑制金属流,形成层流充填型腔。多层泡沫结构吸附氧化夹杂等。现在使用的过滤器有很高的体积孔隙度(90%),很     

自蔓燃高温合成碳化物陶瓷

介绍了自蔓延高温合成（SHS）制备碳化物粉体。单晶、多孔材料和致密材料。重点讨论了通过控制反应参数,控制合成材料的组织结构和性能的一些措施。以催化剂载体、泡沫陶瓷过滤器、粗TiC磨料以及Si-SiC复合材料为例,介绍了SHS在材料合成中的应用和控制方法。参考Ti3SiC2陶瓷的合成,讨论了多元SHS体系中产物相的控制问题。另外,文中还介绍了提高烧结助剂BxC在SiC中的分散性,从而提高SHSSiC烧结性的实例。     

液相等离子喷涂La2O3-Y2O3-ZrO2涂层的组织结构与性能

采用一定化学配比的ZrOCl2·8H2O、YCl3和LaCl3三种盐溶液合成前驱体溶胶作为等离子喷涂液体喂料,制备二元稀土氧化物氧化镧与氧化钇共稳定的氧化锆陶瓷涂层,并测试分析了该涂层的组织结构、高温相稳定性及隔热性能。结果表明,氧化镧与氧化钇共稳定的氧化锆陶瓷涂层具有良好的隔热性能及高温相稳定性。     

莫来石/碳化硅复相泡沫陶瓷的制备及抗压强度研究

以碳化硅微粉作为原料,并选用Al2O3、高岭土和Mg O作为烧结助剂,同时选用羧甲基纤维素钠(CMC)、聚丙烯酰胺(PAM)和可溶性淀粉作为添加剂,通过有机泡沫浸渍法制备出莫来石/碳化硅复相泡沫陶瓷材料。研究了不同原料组成、不同烧结温度等工艺参数对所制备的莫来石/碳化硅复相泡沫陶瓷物相组成、微观结构的影响,同时对莫来石/碳化硅复相泡沫陶瓷的孔隙率、力学性能进行了测试。研究结果表明:莫来石/碳化硅复相泡沫陶瓷的微观结构控制主要受碳化硅含量的影响,随着碳化硅含量的增加,莫来石/碳化硅复相泡沫陶瓷的孔隙率有明显的降低,但抗压强度随之提高;随着烧结温度的提高,孔棱的致密度增加,抗压强度亦显著提高;莫来石/碳化硅复相泡沫陶瓷的最佳烧结温度为1600℃,陶瓷粉料中最佳的Si C含量为35%。在1600℃烧结温度下,碳化硅的含量为35%时,获得了孔隙率为76.19%和抗压强度为4.63 MPa的莫来石/碳化硅复相泡沫陶瓷。     

高温窑炉内衬用隔热材料的对比研究

将一种新型无纤维高温隔热材料——泡沫陶瓷和市面上的8种在1 600℃以上高温窑炉内衬用陶瓷纤维隔热材料的物理性能、显微结构和物相组成进行对比。结果表明:(1)泡沫陶瓷Zeolite CF3100表现出不同于陶瓷纤维的显微结构,开孔和闭孔气孔分布均匀、致密性好,不含有纤维、粒状或球状颗粒,也不含无机或有机结合剂,物相中莫来石和刚玉相的总含量最高、非晶相含量最低,且不含有方石英相,其性能高于其它陶瓷纤维产品;(2)其它8种陶瓷纤维产品性能各有优劣。     

铝用泡沫陶瓷过滤板改性研究

以氧化铝为主要原料,按照优化设计的成分配方添加辅助配料,采用有机泡沫前驱体浸渍法,研制了用于铝液过滤净化用的高性能泡沫陶瓷过滤板。性能表征的结果表明：添加了改性剂的泡沫体的通孔率在90％以上,抗压强度最高可达2MPa;考虑到材料的形状稳定性因素,在基本组分中添加8％左右的膨润土可使泡沫陶瓷过滤器的改性效果达到最佳。扫描电镜对材料的微观形貌进行的表征结果表明：泡沫陶瓷基体材料结晶度越高,材料常温强度越高。     

高温合金用陶瓷泡沫过滤器的发展

据美国铸造工作者学会会刊1985年第93卷P339-342报道:采用多孔陶瓷泡沫过滤器过滤铸造合金技术正在得到广泛的应用。但是,在过滤器的材质和设计等方面仍有许多问题值得进一步研究。为了在1500～1700℃温度下过滤高温合     

Catalytic oxidation of formaldehyde over CeO_2-Co_3O_4 catalysts

A series of CeO_2-Co_3O_4 mixed oxide catalysts with different Co/(Co+Ce) atomic ratios were synthesized by citric acid sol-gel method and used for catalytic oxidation of formaldehyde(HCHO). Many techniques such as Brumauer-Emmett-Teller(BET), X-ray diffraction(XRD), scanning electron microscopy(FE-SEM), temperature programmed reduction(H_2-TPR), temperature-programmed desorption(O_2-TPD) and X-ray photoelectron spectroscopy(XPS) were used to characterize catalysts. The results of catalytic performance tests showed that the catalyst CeO_2-Co_3O_4 with Co/(Co+Ce) ratio of 0.95 exhibited the best performance, and the temperature of complete oxidation of HCHO was 80 oC. The analytical results indicated that the addition of CeO_2 enhanced the specific surface area of Co_3O_4 and the fine dispersion of both of them. Moreover, the strong interaction between CeO_2 and Co_3O_4 resulted in the unique redox properties, which enhanced the available surface active oxygen and led to high valence state of cobalt oxide species. All those effects played crucial roles in the excellent performance of CeO_2-Co_3O_4 for the HCHO oxidation.     

High activity of CeO_2-TiO_2 composites for deep oxidation of 1,2-dichloroethane

CeO_2-TiO_2 catalysts prepared by different methods were investigated for deep oxidation of 1,2-dichloroethane(DCE),as a typical representative of the chlorinated volatile organic compounds(CVOCs).Characterization analysis reveals that CeO_2-TiO_2 catalysts prepared by sol-gel and coprecipitation methods exhibit higher specific area,CeO_2 and TiO_2 particles are highly dispersed into each other and the reducibility and mobility of active oxygen species are obviously promoted due to the strong interaction between the two catalysts CeO_2 and TiO_2,resulting in higher catalytic activity for DCE oxidation to and less chlorinated byproduct.The high calcination temperature would lead to the formation of a new monoclinic phase Ce_(0.3)Ti_(0.7)O_2 and sintering,which is the main reason for the catalytic activity for DCE oxidation markedly decreases.     

CeO_2/CuO catalysts using different template agent for preferential CO oxidation in H_2-rich stream

The CeO_2/CuO catalysts using different template agent(F68 L64, F127 and P123) were synthesized by the simple template and impregnation method. They were characterized by FESEM, XRD, N2 physisorption and H2-TPR techniques. It is found that the CeO_2/CuO catalysts are double pore distribution, and CeO_2 can enter into the gap of CuO supports and form the contact interface of copper and cerium. Among the asprepared catalysts, the CeO_2/CuO-F127 catalyst displays better activity at lower temperature and the CeO_2/CuO-P123 catalyst presents higher activity at higher temperature. The CeO_2/CuO-P123 catalyst has the smallest crystallite sizes of CuO and CeO_2 as well as the largest size of cubes, which may improve the interaction of copper and cerium and enhance the performance of CO oxidation.     

Influence of cobalt on performance of Cu-CeO_2 catalysts for preferential oxidation of CO

Copper and cobalt oxides supported on CeO_2 were investigated for preferential oxidation of carbon monoxide(CO-PROX) in the presence of excess hydrogen and CO_2.(Cuo)_(1-x)(Co_3 O_4)_(x/3)-(CeO_2)_(2.5)(x=0,0.25,0.50,0.75,0.85 and 1) catalysts were prepared by coprecipitation method.These mixed oxide catalysts were characterized by several physicochemical techniques,such as BET surface area(S_(BET)),X-ray diffraction(XRD),high resolution transmission electron microscopy(HRTEM),temperature programmed reduction(TPR) and X-ray photoelectron spectroscopy(XPS).XRD studies show the peaks related to CuO and Co_3 O_4 phases in copper and cobalt containing CeO_2 catalysts.The average particle size of the CeO_2 crystallites is in the range of 8-10 nm as evaluated from HRTEM studies.XPS studies demonstrate that Cu,Co and Ce in(cuO)_(1-x)(Co_3O_4)_(x/3)-(CeO_2)_(2.5) catalysts are presented in+2 and +1,+3 and +2 and +4 and +3 oxidation states,respectively.The catalyst with x=0.75 shows better activity and selectivity towards CO-PROX.Though the catalyst with only copper(CuO-CeO_2,x=0) shows good activity but reverse water gas shift(RWGS) reaction is noticed at high temperature.On the other hand,RWGS reaction is suppressed on the cobalt containing CuO-ceO_2 catalyst.Cobalt on CeO_2 with x=1 shows hardly any activity for PRoX reaction at low temperatures.No methanation activity is observed on CuO-CeO_2 or Co_3O_4-CeO_2 catalysts.In contrast,combination of copper and cobalt on CeO_2 shows methanation of CO where enhanced activity is observed with increasing in cobalt content.     

Determination of the Phase Distribution in Sintered TRIP‐Matrix / Mg‐PSZ Composites using EBSD

Metal matrix composites (MMC) containing TRIP‐steel/Mg‐PSZ were processed by cold pressing and conventional sintering in different atmospheres. The MMC was based on austenitic steel in the system Fe‐Cr‐Mn‐Ni showing transformation induced plasticity (TRIP). Depending on the sintering temperature, the sintering atmosphere and the steel composition the phase compositions of MgO partially stabilized zirconia (Mg‐PSZ) were analysed by scanning electron microscopy (SEM), energy dispersive X‐ray microanalysis (EDX) as well as electron backscatter diffraction (EBSD). The interactions between the alloying elements of austenitic stainless steel and the ceramic stabilizer (MgO) as well as the technological parameters lead to a significant change in the phase composition of the Mg‐PSZ. The changes can be analysed by EBSD due to the high spatial resolution.     

Mesoporous CeO_2-C hybrid spheres as efficient support for platinum nanoparticles towards methanol electrocatalytic oxidation

The development of direct methanol fuel cells(DMFCs) is partially limited by the poor kinetics of methanol oxidation reaction(MOR) at the anode side.It was reported that the interaction between Pt and CeO_2 enhances the electrocatalytic performance of Pt catalyst for MOR.In this work,a hybrid material(CeO_2-C) composed of CeO_2 and carbon was successfully prepared by a simple hydrothermal method followed by calcination in inert atmosphere.The hierarchically porous nanostructure and especially good electronic conductivity of CeO_2-C make it an excellent support for Pt particles for application in electrocatalytic process.TEM investigation reveals that triple-phase interface of Pt,carbon and CeO_2 forms in Pt/CeO_2-C catalyst.Performance of the as-prepared catalyst for MOR was studied in alkaline medium.The Pt/CeO_2-C catalyst shows superior catalytic performance for MOR compared with Pt/CeO_2 and the physical mixture of Pt/CeO_2 and acetylene black(Pt/CeO_2+C).The significantly improved performance can be attributed to the synergetic effect between Pt particles and CeO_2-C support,and the better conductivity of CeO_2-C.This study provides a possible method to expand the application potential of CeO_2 materials in MOR,and may also be used in other electrocatalytic process.     

Effect of cerium oxide prepared under different hydrothermal time on electrocatalytic performance of Pt-based anode catalysts

In this paper,CeO_2 with a pore size of 2-4 nm was synthesized by hydrothermal method.The CeO_2 modified graphene-supported Pt catalyst was prepared by the microwave-assisted ethylene glycol reduction chloroplatinic acid method,and the effect of the addition of CeO_2 prepared by different hydrothermal reaction time on the catalytic performance of Pt-based catalysts was investigated.The microstructures of CeO_2 and catalysts were characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),specific surface area and pore size analyzer(BET),scanning electron microscopy(SEM) and electron spectroscopy(EDAX),transmission electron microscopy(TEM),and the catalysts electrochemical performance was tested by electrochemical workstation.The results show that the catalytic performance of the four catalysts with CeO_2 is better than that of the catalyst without CeO_2.Adding CeO_2 with a specific surface area of 120.15 m~2/g prepared by hydrothermal reaction time of 39 h to Pt/C synthesis catalyst,its electrocatalytic performance,stability and resistance to poisoning are the best.The electrochemical active surface area is 102.83 m~2/g,the peak current density of ethanol oxidation is 757.17 A/g and steady-state current density of 1100 s is 108.17 A/g which shows the lowest activation energy for ethanol oxidation reaction.When the cyclic voltammogram is scanned for 500 cycles,the oxidation peak current density retention rate is 87.74%.     

CeO2基固体电解质材料研究进展

稀土或碱土氧化物掺杂铈基电解质在中低温下具有高的离子电导率,被认为是一种很有前途的电解质材料.本文主要对各种掺杂铈基电解质材料研究及在固体氧化物中的应用进行了综述.对掺杂铈基电解质的制备方法进行简单介绍.     

制备条件对大颗粒氧化铈流动性的影响

对草酸沉淀法和碳酸氢铵沉淀法制备大颗粒氧化铈的流动性进行了研究。在草酸沉淀法中,研究了搅拌速度、沉淀温度、陈化时间、沉淀剂的加入速度和灼烧温度等条件对C eO2流动性能的影响,这些制备条件对C eO2粉体的流动性影响不是很大,制得的大颗粒氧化铈的流动性指数介于70~80之间,流动性良好;碳酸盐沉淀法制备大颗粒C eO2,晶种和添加剂可以改善C eO2粉体的流动性,加入适量的晶种和添加剂,也可以制得流动性指数都介于70~80之间,流动性良好的大颗粒C eO2。     

高比表面积纳米CeO_2的制备

采用模板法制备高比表面积纳米CeO_2. 详细考察了铈盐和NaOH滴加速度、晶化时间和温度、铈盐种类、表面活性剂用量等对CeO_2比表面、晶粒尺寸的影响. 结果表明, 当CeCl_3加入速度=2.5 ml·min~(-1)、 NaOH加入速度=3 ml·min-1、晶化温度=90 ℃、晶化时间=24 h、 CeCl3∶ C_(12)H_(25)SO_4Na∶ NaOH∶ H2O=1∶ 2.7∶ 7.3∶ 1100(摩尔比)、焙烧温度=200 ℃时, CeO_2的比表面积和晶粒尺寸分别为457 m~2·g~(-1)和2.0 nm. 这种高比表面纳米CeO_2与常规CeO_2相比, 具有独特的物理、化学性质, 有望成为一种应用广泛的新型材料.