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采用氧化铝为主要原料制备出多孔陶瓷分离膜支撑体,对原料粉体做了TG/DSC曲线分析,研究了支撑体的烧结温度对收缩率的影响及烧结温度、保温时间和原料粉体粒径对孔结构、孔径的影响,造孔剂用量对孔隙率的影响。结果表明:在烧结温度为1200℃,保温时间4h,控制造孔剂用量大于20%时,制备出孔径分布均匀,孔隙率大于50%,符合透水要求的多孔陶瓷分离膜支撑体。 相似文献
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《中国陶瓷》2019,(9)
实验以黄土为原料,利用滚压成型制备黄土基陶瓷膜支撑体试样,研究了高岭土添加量和烧结温度对支撑体试样的抗折强度、纯水通量及微观形貌的影响。采用万能材料试验机、扫描电镜、实验室自制装置等仪器设备进行表征,并利用X射线粉末衍射仪、压汞仪对最佳样进行物相组成、孔径分布分析。结果表明:高岭土添加量为4%、烧结温度为1120℃时,烧结得到的黄土基支撑体的性能最佳,此时支撑体的抗折强度为67 MPa,纯水通量为1465 L/(m~2·h·bar),中值孔径为3568.40 nm,主峰孔径分布范围为1416.59~5532.03 nm,孔隙率为16.67%,微观结构良好,物相组成中莫来石和石英含量较高。 相似文献
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《耐火材料》2019,(3)
为节约制作成本,降低SiC陶瓷膜支撑体烧结温度,以SiC和ρ-Al_2O_3为主要原料,采用碱式碳酸镁(BMC,外加质量分数分别为0、0. 5%、1%和1. 5%)为助烧结剂,于1 300~1 420℃无压烧结制备出原位反应结合SiC支撑体,并研究了BMC添加量对支撑体性能的影响。结果表明:添加BMC加剧了SiC表面氧化,使原位反应结合温度降低(1 300℃),促进SiC颗粒间颈部形成,提高了试样的强度;当BMC添加量从0. 5%逐渐增加到1. 5%,试样在不同温度烧后的显气孔率逐渐降低; BMC助烧剂的最佳添加量为1. 0%(w),在1 360℃烧后制备的多孔SiC支撑体的常温抗折强度为25. 3 MPa,是未添加助烧剂的2. 7倍,且在1 050℃风冷热震5次后,常温抗折强度保持率90%以上,热震后的常温抗折强度19 MPa以上,可满足高温烟气净化用膜支撑体的指标要求。 相似文献
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以粒度≤0.063mm的SiC为主要原料,分别加入30%(质量分数)的Al2O3-Y2O3与10%的Al2O3-高岭土复合助烧剂,并外加不同量(分别为12.8%、26.3%、30.0%和36.4%)的造孔剂羧甲基纤维素钠(CMC),制样后首先在空气炉中经过300℃2h或1100℃4h的预烧,然后在真空炉中于1550℃4h真空烧结而制备成SiC多孔陶瓷,并研究了助烧剂种类以及造孔剂CMC外加量对SiC多孔陶瓷显微组织、显气孔率及抗折强度的影响。结果显示:采用Al2O3-Y2O3作为助烧剂的SiC多孔陶瓷比Al2O3-高岭土作助烧剂的具有较高的抗折强度,显气孔率稍有减小;随着羧甲基纤维素钠量的增加,加入两种助烧剂的SiC多孔陶瓷均表现为显气孔率增加,抗折强度降低。 相似文献
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陶瓷支撑体是多孔陶瓷膜应用的基础。对于传统陶瓷支撑体(如氧化铝),昂贵的原料价格及较高的烧结成本限制了其进一步应用。因此,选用合适的天然矿物原料来实现陶瓷支撑体的低成本制备成为当前研究重点。本工作以高岭土、滑石、碳酸钙为原料,制备出系列多孔陶瓷支撑体。采用热膨胀仪、X射线衍射仪、扫描电子显微镜、压汞仪、万能试验机对坯体的烧结特性以及多孔陶瓷支撑体的物相组成、显微结构、孔径尺寸分布、抗弯强度和耐酸碱腐蚀性进行了研究。结果表明:坯体具有优良的低温烧结特性,通过化学反应烧结机制实现了多孔陶瓷支撑体的制备。烧结温度在1 000~1 200℃间较为适宜,所得支撑体的显微结构均匀,孔径呈单峰分布,开口气孔率、平均孔径尺寸、抗弯强度、0.1 MPa气体压力差下氮气通量分别为49.8%~49.4%、1.09~1.83μm、40.57~28.85 MPa、119~340 m3·m–2·h–1,同时具有良好的耐碱腐蚀性能。 相似文献
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以煅烧α-Al2O3为原料,稀土氧化镧(La2O3)为添加剂,羧甲基纤维素为成型粘结剂,通过混料、困料、研磨、模压成型、高温烧结等工序制备了氧化铝多孔陶瓷,研究了烧结温度及La2O3添加量对氧化铝多孔陶瓷的线收缩率、体积密度、孔隙率、抗折强度和微观形貌的影响。结果表明:在相同烧结温度下,随稀土添加量的增加,多孔陶瓷的体积密度、线收缩率与抗折强度均降低,而孔隙率则逐渐增加。微观形貌与X衍射分析表明,稀土La2O3的加入,抑制了氧化铝颗粒间的烧结,并在高温下与氧化铝反应生成了片状晶体LaAl11O18,片状晶LaAl11O18阻碍了氧化铝晶粒的长大,进而抑制了坯体的收缩,最终使得氧化铝多孔陶瓷具有较高的孔隙率。 相似文献
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Graphite trifluoromethylsulfate C12SO3CF3, a new binary graphite salt is formed by the irreversible solvolysis of C8SO3F in a large excess of trifluoromethylsulfuric acid. The salt is identified as a stage one intercalation compound with a C0 value of 8.12 Å and characterised by microanalysis, epr and 19F NMR spectroscopy. Both Raman spectra, in the back scattering configuration, and IR spectra, in transmission as well as reflection geometries, are used to support an ionic formulation as C12+SO3CF3?. 相似文献
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The mixed ionic and electronic conductors of La0.9Ca0.1Ni0.5Co0.5O3-Ce0.8Sm0.2O1.9 (LCNC-SDC) are investigated systematically for potential application as a cathode for solid oxide fuel cells based on a Ce0.8Sm0.2O1.9 (SDC) electrolyte. The electrochemical impedance spectroscopy (EIS) measurements are performed in air over the temperature range of 600-850 °C to determine the cathode polarization resistance. The exchange current densities for oxygen reduction reaction (ORR), determined from the low-field cyclic voltammetry, high-field cyclic voltammetry, and EIS data are systematically investigated. The activation energies (Ea) for ORR determined from the slope of Arrhenius plots are in the range of 102.33-150.73 kJ mol−1 for LCNC-SDC composite cathodes. The experimental results found that LCNC-SDC (70:30) composite cathode has a maximum exchange current density and a minimum polarization resistance of 0.30 Ω cm2 for 850 °C among LCNC-SDC composite cathodes. 相似文献
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Yun Liu Guoqiang Tan Zhengjun Chai Long Lv Zhongwei Yue Mintao Xue Huijun Ren Ao Xia 《Ceramics International》2019,45(3):3522-3530
Bi0.96Sr0.04Fe0.98Co0.02O3/CoFe2O4(BSFCO/CFO) bilayered thin films with different thicknesses of the BSFCO layer are synthesized on FTO/glass substrates by chemical solution deposition method (CSD). The influence of BSFCO thickness on the microstructure, dielectric relaxation, ferroelectric properties and resistive switching (RS) of the thin films are researched. Strain exists in the prepared thin films and gives rise to structural distortion, which has an effect on charged defects and ferroelectric polarization. Dielectric relaxation that is closely related to the interfacial polarization at the BSFCO/CFO interface is observed, and the dielectric loss peaks along with decreasing intensity shift to high frequency with decreasing strain. The Maxwell-Wagner two-layer model is adopted to investigate the mechanism of dielectric relaxation, and the relaxation time τ is calculated and it shown to be directly proportional to the strain. It is found that the dielectric properties, including low dielectric loss, can be improved by controlling the BSFCO layer thickness. The ferroelectric properties improve with the decreasing strain, the 12-BSFCO/CFO thin film possesses a large Pr ~ 102.9?μC/cm2 at 660?kV/cm. The observed resistive switching (RS) behavior is attributed to the interfacial conduction mechanism, it is found that strain-dependent the ferroelectric polarization switching modulates the width of depletion layer and the height of potential barrier at the interface, resulting in the different resistance states. 相似文献
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采用固相法制备了 Na0.5Bi0.5TiO3–K0.5Bi0.5TiO3–BaTiO3–SrTiO3(NBT–KBT–BT–ST)陶瓷,该体系是按(1–2x)(0.8NBT–0.2KBT)–x(0.94NBT–0.06BT)–x(0.74NBT–0.26ST) (x = 0.10、0.20、0.25、0.30、0.35、0.40、0.45)组合而成的,研究了该系陶瓷的结构与电性能。结果表明:所有样品都处于三方–四方准同型相界区域。该系陶瓷在准同型相界附近表现出了优异的压电性能,压电常数 d33、机电耦合系数 kp和剩余极化强度 Pr随 x 的增加先升高后降低,其中 x=0.35 陶瓷的电性能最佳:d33= 210 pC/N,kp= 0.319,Pr= 39.3 μC/cm2,Ec= 20.2 kV/cm,是一种良好的无铅压电陶瓷候选材料。依据准同型相界组成的线性组合规律来寻找具有优异压电性能的 NBT–KBT–BT–ST 陶瓷准同型相界组成是可行的。 相似文献
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以尿素为沉淀剂,柠檬酸钠为络合剂,采用均相沉淀法制备Ni~(2+)-Fe~(3+)-CO_3~(2-)-LDHs。以制备的Ni~(2+)-Fe~(3+)-CO_3~(2-)-LDHs为前驱体,分别与Na Cl和对甲苯磺酸钠进行离子交换反应得到Ni~(2+)-Fe~(3+)-C_7H_7SO_3~--LDHs新型催化剂,成功实现对甲苯磺酸根负载Ni~(2+)-Fe~(3+)-LDHs。研究表明,Ni~(2+)-Fe~(3+)-C_7H_7SO_3~--LDHs为介孔材料,比表面积为165.6 m~2·g~(-1),平均孔径为14.7 nm,较大比表面积和空隙结构增强了其吸附性能和催化活性。 相似文献
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Surface-phase ZrO2 on SiO2 (SZrOs) and surface-phase La2O3 on Al2O3 (SLaOs) were prepared with various loadings of ZrO2 and La2O3, characterized and used as supports for preparing Pt/SZrOs and Pt/SLaOs catalysts. CH4/CO2 reforming over the Pt/SZrOs and Pt/SLaOs catalysts was examined and compared with Pt/Al2O3 and Pt/SiO2 catalysts. CO2 or CH4 pulse reaction/adsorption analysis was employed to elucidate the effects of these surface-phase oxides.
The zirconia can be homogeneously dispersed on SiO2 to form a stable surface-phase oxide. The lanthana cannot be spread well on Al2O3, but it forms a stable amorphous oxide with Al2O3. The Pt/SZrOs and Pt/SLaOs catalysts showed higher steady activity than did Pt/SiO2 and Pt/Al2O3 by a factor of three to four. The Pt/SZrOs and Pt/SLaOs catalysts were also much more stable than the Pt/SiO2 and Pt/Al2O3 catalysts for long stream time and for reforming temperatures above 700 °C. These findings were attributed to the activation of CO2 adsorbed on the basic sites of SZrOs and SLaOs. 相似文献
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Cu2O/TiO2, Bi2O3/TiO2 and ZnMn2O4/TiO2 heterojunctions were studied for potential applications in water decontamination technology and their capacity to induce an oxidation process under VIS light. UV–vis spectroscopy analysis showed that the junctions-based Cu2O, Bi2O3 and ZnMn2O4 are able to absorb a large part of visible light (respectively, up to 650, 460 and 1000 nm). This fact was confirmed in the case of Cu2O/TiO2 and Bi2O3/TiO2 by photocatalytic experiments performed under visible light. A part of the charge recombination that can take place when both semiconductors are excited was observed when a photocatalytic experiment was performed under UV–vis illumination. Orange II, 4-hydroxybenzoic and benzamide were used as pollutants in the experiment. Photoactivity of the junctions was found to be strongly dependent on the substrate. The different phenomena that were observed in each case are discussed. 相似文献
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A bi-layered composite cathode of La0.8Sr0.2MnO3 (LSM)-YSZ and LSM-La0.4Ce0.6O1.8 (LDC) was fabricated for anode-supported solid oxide fuel cells with a thin YSZ electrolyte film. The cell with the bi-layered composite cathode displayed better performance than the cell with the corresponding single-layered composite cathode of LSM-LDC or LSM-YSZ. At 650 °C, the cell with the bi-layered composite cathode gave a higher maximum power density than the cells with the single-layered LSM-LDC and LSM-YSZ composite cathodes, by 52% and 175%, respectively. The impedance spectra results show that the thin LSM-YSZ interlayer not only improves the cathode/electrolyte interface but also reduces the polarization resistance of the cathode. The activation energy for oxygen reduction on the bi-layered composite cathode is much smaller than that on LSM-YSZ composite cathode, and it is suggested that the special redox property of Ce4+/Ce3+ in LDC facilitates the oxygen reduction process on the bi-layered composite cathode. The cell with the bi-layered composite cathode operated quite stably during a 100 h run. 相似文献
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Thadsanee Thongkanluang Treedej KittiauchawalPichet Limsuwan 《Ceramics International》2011,37(2):543-548
Green pigments with high near infrared reflectance based on a Cr2O3-TiO2-Al2O3-V2O5 composition have been synthesized. Cr2O3 was used as the host component and mixtures of TiO2, Al2O3 and V2O5 were used as the guest components. TiO2, Al2O3, and V2O5 were mixed into 39 different compositions. The spectral reflectance and the distribution of pigment powder were determined using a spectrophotometer and a scanning electron microscope, respectively. It was found that a pigment powder sample S9 with a Cr2O3-TiO2-Al2O3-V2O5 composition of 80, 4, 14 and 2 wt%, respectively, gives a maximum near infrared solar reflectance of 82.8% compared with 49.0% for pure Cr2O3. The dispersion of pigment powders in a ceramic glaze was also studied. The results show that the pigment powder sample S9 is suitable for use as a coating material for ceramic-based roofs. 相似文献