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以铝酸钙水泥(CAC)为结合剂的传统Al2O3-MA浇注料在热处理过程中生成CA6,导致浇注料产生膨胀而降低其抗渣性能。巴西研究人员制备了氧化铝溶胶(ColAlu)结合的Al2O3-MA浇注料,以提高其抗渣侵蚀性,并与水合氧化铝(HA)结合和铝酸钙水泥结合的Al2O3-MA浇注料进行了对比。 相似文献
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采用电冶矾土刚玉为骨料,研究了基质中MgO/Al2O3比例对Al2O3-尖晶石浇注料理化性能的影响,并对渣蚀后的样品进行了SEM和EDAX分析,讨论了Al2O3-尖晶石浇注料的渣蚀机理. 相似文献
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研究了几种分散剂对Al2O3-SiC-C系超低水泥高铝浇注料自流性的影响。根据表观黏度、基质的pH值和浇注料的自流值来评价不同分散剂对高铝浇注料性能的影响。研究表明,在Al2O3-SiC-C系浇注料中,加入0.06%聚丙烯酸钠,浇注料的流动性最好。 相似文献
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为了解决Al2O3-SiC-C系铁沟浇注料在高温使用过程中易氧化的问题,以棕刚玉颗粒、致密刚玉细粉、碳化硅颗粒和细粉、球状沥青、硅粉、Secar 71水泥、氮化硅铁等为原料,制备了Al2O3-SiC-C系铁沟浇注料,并研究了添加5%(w)氮化硅铁对该浇注料施工性能、物理性能、抗氧化性的影响,同时分别采用静态抗渣和回转抗渣试验对抗渣性能进行评价。结果表明:1)与不加氮化硅铁的常规铁沟浇注料相比,添加氮化硅铁的铁沟浇注料的常温强度略低,但是同样具备良好的施工性能和足够的脱模强度;2)添加氮化硅铁的铁沟浇注料具有较高的高温抗折强度和高温抗氧化性能;3)添加氮化硅铁的铁沟浇注料具有良好的静态抗渣能力,但是在强氧化环境和热态冲蚀同时作用的铁沟部位,不建议使用含氮化硅铁的Al2O3-SiC-C材料。 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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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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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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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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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
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The influences of Li2O-B2O3-SiO2 glass (LBS) on the activation energy, phase composition, the stability of the structure and microwave dielectric properties of Zn0.15Nb0.3Ti0.55O2 ceramics have been systematically investigated. LBS glass acted as flux former and contributed to the reactive liquid-phase sintering mechanism, which remarkably lowed the sintering temperature from 1150?°C to 900?°C and enhanced the shrinkage and densification of ceramic at the low sintering temperatures. The ceramics with 1.5?wt% LBS glass sintered at 900?°C for 3?h show great properties: εr = 73.59, Q × f = 8024?GHz, τf = 270.54?ppm/°C. 相似文献
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Chao Han Jiagang Wu Chaohui Pu Sha Qiao Bo Wu Jianguo Zhu Dingquan Xiao 《Ceramics International》2012
Pr2O3-doped Ba0.85Ca0.15Ti0.90Zr0.10O3 (BCTZ-xPr) ceramics were prepared by the conventional solid-state method. A tetragonal phase is only observed in these ceramics, and the introduction of Pr2O3 decreases their sintering temperature without affecting negatively the piezoelectric constant. Enhanced ferroelectric properties were obtained in these BCTZ-xPr ceramics. The ceramic with x=0.06 wt% exhibits a good electrical behavior of d33∼460 pC/N, kp∼47.6%, εr∼4638, and tan δ∼0.015 when sintered at a low temperature of ∼1400 °C. As a result, the BCTZ-xPr ceramic is a promising candidate for lead-free piezoelectric ceramics. 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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Sintering kinetics of the system Si3 N4-Y2O3 -Al2 O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si3 N4 were studied with additions of 4 to 17 wt% Y2 O3 and 4 wt% A12 O3 . Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si3 N4 and glass or β '-Si3 N4 , α '-Si3 N4 , and glass. The compositions and amounts of the residual glassy phases are estimated. 相似文献