ZrO2-mullite nano-ceramics were fabricated by in-situ controlled crystallizing from SiO2-Al2O3-ZrO2 amorphous bulk. The thermal transformation sequences of the SiO2-Al2O3-ZrO2 amorphous bulk were investigated by X-ray...ZrO2-mullite nano-ceramics were fabricated by in-situ controlled crystallizing from SiO2-Al2O3-ZrO2 amorphous bulk. The thermal transformation sequences of the SiO2-Al2O3-ZrO2 amorphous bulk were investigated by X-ray diffraction, infrared spectrum, scanning electron microscope and differential scanning calorimetric. And the mechanical properties of the nano-ceramics were studied. The results show that the bulks are still in amorphous state at 900 ℃ and the t-ZrO2 forms at about 950 ℃ with a faint spinel-like phase which changes into mullite on further heating. ZrO2 and mullite become major phases at 1 100 ℃ and an amount of m-ZrO2 occur at the same time. The sample heated at 950 ℃ for 2 h and then at 1 100 ℃ for 1 h shows very dense and homogenous microstructure with ball-like grains in size of 20-50 nm. With the increase of crystallization temperature up to 1 350 ℃, the grains grow quickly and some grow into lath-shaped grains with major diameter of 5 μm. After two-step treatment the highest micro-hardness, flexural strength and fracture toughness of the samples are 13.72 GPa, 520 MPa and 5.13 MPa·m1/2, respectively.展开更多
SiO2-Al2O3-ZrO2 glasses with different nucleating agents were crystallized under special processing schedule. The microstructure and mechanical properties of the glass-ceramics in SiO2-Al2O3-ZrO2 system were investiga...SiO2-Al2O3-ZrO2 glasses with different nucleating agents were crystallized under special processing schedule. The microstructure and mechanical properties of the glass-ceramics in SiO2-Al2O3-ZrO2 system were investigated by differential scanning calorimetry, scanning electron microscopy, X-ray diffraction and three-point bending method. The results show that ZrO2 is not an effective nucleating agent in SiO2-Al2O3-ZrO2 system, while TiO2 is effective for the separation of spinel, and P2O5 facilitates solubility of ZrO2 in glass and crystallization. The main crystalline phases of the glass-ceramics are spinel, anorthite and tetragonal zirconia. With the increase of ZrO2 content in the glass, glass-ceramics show higher bending strength (120MPa) than others.展开更多
Through measuring the coefficient of linear expansion, the structure and properties of the Li2O-Al2O3-SiO2 low expansion glass ceramics containing B2O3 are studied by JR and XRD. It is shoutn that the IR method is eff...Through measuring the coefficient of linear expansion, the structure and properties of the Li2O-Al2O3-SiO2 low expansion glass ceramics containing B2O3 are studied by JR and XRD. It is shoutn that the IR method is efficient in the study of the glass-ceramics structure. There is a " Boron abnormality" in the system which has an important influence on the properties of the glass-ceramics.展开更多
BNp/Al2O3-SiO2 system ceramic matrix composites with different volume fractions (10%-60%) of hexagonal BN particulates (BNp) were prepared by hot-press sintering technique. Phase components, microstructure, mechan...BNp/Al2O3-SiO2 system ceramic matrix composites with different volume fractions (10%-60%) of hexagonal BN particulates (BNp) were prepared by hot-press sintering technique. Phase components, microstructure, mechanical properties and plasma erosion resistance were also investigated. With the increase of h-BNp content, relative density and Vickers' hardness of the composite ceramics decrease, while the flexural strength, elastic modulus and fracture toughness increase and then decrease. The plasma erosion resistance linearly deteriorated with the increase of BNp content which is mainly determined by the density, crystal structure and atomic number of the elements.展开更多
CaO-B203-SiO2 (CBS) glass powders are prepared by conventional glass melting method at different melting temperatures whose properties and microstructures are characterized by X-ray diffraction (XRD) and scanning ...CaO-B203-SiO2 (CBS) glass powders are prepared by conventional glass melting method at different melting temperatures whose properties and microstructures are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is found that there are SiO2 and some unknown phases in CBS glass melting liquid from 1 300 ℃ to 1 500 ℃ and the amount of these phases decreases with the increase of the melting temperature. The CBS glass melted at 1 450 ℃ could be sintered from 830 ℃ to 930 ℃ and the bulk densities of the samples are all higher than 2.4 g/cm^3. From the points of the properties and energy conservation, the melting temperature of 1 450 ℃ is the optimal melting temperature. The glass ceramic sintered at 850 ℃ exhibits better dielectric properties: er=6.33, tan6=2.2×10^-3 at 10 GHz, and the major phases of the samples are CaSiO3, CaB2O4 and SiO2.展开更多
This paper reports that polycrystalline (α-Al2O3:C ceramics are fabricated by conventional ceramics process. The excitation, emission spectra, thermoluminescence (TL) and optical stimulated luminescence (OSL) ...This paper reports that polycrystalline (α-Al2O3:C ceramics are fabricated by conventional ceramics process. The excitation, emission spectra, thermoluminescence (TL) and optical stimulated luminescence (OSL) of α-Al2O3:C polycrystalline ceramics are investigated. There exists 410nm maximum emission peak which is caused by recombination of an electron with F+ centre to produce an excited F centre. The samples show three clear TL glow peaks at 405, 493 and 610 K. The attenuation constant of exponentially decaying fast component (τ1) and slow component(τ2) of OSL curve are 8.43s and 41.73s, respectively. Those fluorescence and thermoluminescence characteristics are similar with α-Al2O3:C crystal.展开更多
The Al2O3 abrasion-resistant ceramics is successfully prepared by using waste aluminum sludge as the main raw material with the addition of a little clay, talc and barium carbonate. The crystal structure and microstru...The Al2O3 abrasion-resistant ceramics is successfully prepared by using waste aluminum sludge as the main raw material with the addition of a little clay, talc and barium carbonate. The crystal structure and microstructure of ceramic are characterized by means of XRD, SEM, etc., and the physical and mechanical properties are also tested. The results show that besides the phase of corundum, a little mullite, Mg-Al spinel and hyalophane phases also exist in the product. These phases are produced via reaction in-situ, which can inhibit the overgrowth of Al2O3 grain in grain boundary, and improve the integral property of the material.展开更多
In this paper, we present a compact low-temperature co-fired ceramic(LTCC) dual-band antenna by using the electromagnetic coupling effect concept for global positioning system(GPS) and universal mobile telecommuni...In this paper, we present a compact low-temperature co-fired ceramic(LTCC) dual-band antenna by using the electromagnetic coupling effect concept for global positioning system(GPS) and universal mobile telecommunication system(UMTS) applications. The overall dimension of the antenna is 8.6 mm × 13.0 mm × 1.1 mm. It consists of double meander lines and a via hole line. The top meander line operates at the upper band, and the bottom radiating patch is designed for the lower band. The via-hole line is employed to connect the double meander lines. Because of the effect of the coupled line,total dimension of the proposed antenna is greatly reduced. With the 2.5: voltage standing wave ratio(VSWR) impedance bandwidth definition, the lower and upper bands have the bandwidths of 110 MHz and 150 MHz, respectively. The proposed antenna is successfully designed, simulated, and analyzed by a high frequency structure simulator(HFSS). And the antenna is manufactured by using the 0.95Zn2SiO4-0.05 CaTiO3ceramics(εr = 7.1, tanδ = 0.00038) that is prepared by ourselves. The results show that the antenna is compact, efficient, and of near omnidirectional radiation pattern.展开更多
微纳米α-Al2O3是一种重要的功能材料,因其优异的硬度、耐磨性、耐腐蚀性和高热稳定性,在表面涂层领域得到了广泛应用。随着微纳米技术的发展,微纳米级α-Al2O3作为添加剂在各涂层体系中的应用得到了深入研究,显示出其能够显著改善涂层...微纳米α-Al2O3是一种重要的功能材料,因其优异的硬度、耐磨性、耐腐蚀性和高热稳定性,在表面涂层领域得到了广泛应用。随着微纳米技术的发展,微纳米级α-Al2O3作为添加剂在各涂层体系中的应用得到了深入研究,显示出其能够显著改善涂层性能的潜力。微纳米α-Al2O3颗粒具有较大的比表面积和表面活性,能够增强涂层的机械性能,如硬度和耐磨性,同时提高涂层的耐腐蚀性和耐高温性能。微纳米α-Al2O3也是一种极优良的改性材料,其与有机硅烷、树脂等材料复合改性,既能大幅提升转化膜的应用效果,对其稳定性和耐候性也有较大的促进作用。在金属表面涂层、陶瓷涂层以及复合材料涂层中,微纳米α-Al2O3添加剂被广泛用于提高涂层的使用寿命和稳定性。此外,它在电子器件、航天航空和汽车工业等高技术领域也展现了广阔的应用前景。未来,随着表面技术的发展,微纳米α-Al2O3无铬钝化领域的市场应用将大幅增长,与其他功能性材料的协同作用和复合材料开发也将成为研究的重点。Micro-nano α-Al2O3 is an important functional material, because of its excellent hardness, wear resistance, corrosion resistance and high thermal stability, has been widely used in the field of surface coating. With the development of micro-nano technology, the application of micro-nano α-Al2O3 as an additive in various coating systems has been deeply studied, showing its potential to significantly improve coating properties. Micro-nano α-Al2O3 particles have a large specific surface area and surface activity, which can enhance the mechanical properties of the coating, such as hardness and wear resistance, while improving the corrosion resistance and high temperature resistance of the coating. Micro-nano α-Al2O3 is also an excellent modified material, and its composite modification with organosilane, resin and other materials can greatly improve the application effect of conversion film, and also has a greater role in promoting its stability and weather resistance. In metal surface coatings, ceramic coatings and composite coatings, micro-nano α-Al2O3 additives are widely used to improve the service life and stability of coatings. In addition, it also shows broad application prospects in high-tech fields such as electronic devices, aerospace and automotive industries. In the future, with the development of surface technology, the market application of micro-nano α-Al2O3 chromium-free passivation will grow significantly, and the synergy with other functional materials and the development of composite materials will also become the focus of research.展开更多
Ba 3Zn Z Co 2 Z Fe 24 O 41 /SiO 2 ( Z varies from 0.0 to 1.2 in step of 0.4) microcrystalline glass ceramics were prepared by citrate sol gel process at 1 200 ℃ in the system of BaO Fe 2O 3 CoO ZnO SiO 2. The samples...Ba 3Zn Z Co 2 Z Fe 24 O 41 /SiO 2 ( Z varies from 0.0 to 1.2 in step of 0.4) microcrystalline glass ceramics were prepared by citrate sol gel process at 1 200 ℃ in the system of BaO Fe 2O 3 CoO ZnO SiO 2. The samples were characterized by X ray diffraction (XRD) and scanning electron microscopy (SEM). The complex dielectric constant and complex permeability of Ba 3Zn Z Co 2 Z Fe 24 O 41 /SiO 2 microcrystalline glass ceramics were measured in the range of 0.16.0 GHz by transmissioneflection coaxial line method. The natural resonance phenomenon was observed in μ ″ spectra for all the Ba 3Zn Z Co 2 Z Fe 24 O 41 /SiO 2 microcrystalline glass ceramics, which was closely affected by the substitution of Zn 2+ ion.展开更多
Al2O3f/Al2O3 ceramic matrix composites(CMC)are promising candidate materials of blades and combustor liners of future gas turbines in light of their higher temperature capability,higher environmental stability and oxi...Al2O3f/Al2O3 ceramic matrix composites(CMC)are promising candidate materials of blades and combustor liners of future gas turbines in light of their higher temperature capability,higher environmental stability and oxidizing-free capacity[1–3].Nevertheless,grain growth,sintering and creep deformation at high operation temperatures are still serious problems for Al2O3f/Al2O3 ceramic matrix composites,which can lead to a reduction in the strength and damage tolerance[2].Moreover,Al2O3 can be corroded by the high temperature water vapor in combustion environments and yields volatile products,such as Al(OH)3[4].Consequently,environmental barrier coatings(EBCs)are necessary for Al2O3f/Al2O3 ceramic matrix composites,which can protect Al2O3f/Al2O3 CMC from high temperature and flowing combustion gas corrosion and thus increase the high temperature capability and the service life of components.展开更多
A ternary composite of TiO2 and a SiO2-Al2O3 aerogel with good photocatalytic activity was prepared by a simple sol-gel method with TiO2 nanoparticles and SiO2-Al2O3 aerogels derived from industrial fly ash.The struct...A ternary composite of TiO2 and a SiO2-Al2O3 aerogel with good photocatalytic activity was prepared by a simple sol-gel method with TiO2 nanoparticles and SiO2-Al2O3 aerogels derived from industrial fly ash.The structural features of the TiO2/SiO2-Al2O3 aerogel composite were investigated by X-ray powder diffraction,Fourier transform infrared spectroscopy,transmission electron microscopy,gas adsorption measurements and diffuse reflectance UV-visible spectroscopy.The optimal conditions for photocatalytic degradation of 2-sec-butyl-4,6-dinitrophenol(DNBP],included an initial DNBP concentration of 0.167 mmol/L at pH = 4.86 with a catalyst concentration of 6 g/L,under visible light irradiation for 5 h.A plausible mechanism is proposed for the photocatalytic degradation of DNBP.Our composite showed higher photocatalytic activity for DNBP degradation than that of pure TiO2.This indicates that this material can serve as an efficient photocatalyst for degradation of hazardous organic pollutants in wastewater.展开更多
Lu2O3-doped ZnO-Bi2O3-based varistor ceramics samples were prepared by a conventional mixed oxide route and sintered at temperatures in the range of 900-1 000°C,and the microstructures of the varistor ceramics sa...Lu2O3-doped ZnO-Bi2O3-based varistor ceramics samples were prepared by a conventional mixed oxide route and sintered at temperatures in the range of 900-1 000°C,and the microstructures of the varistor ceramics samples were characterized by X-ray diffractometry(XRD)and scanning electron microscopy(SEM);at the same time,the electrical properties and V-I characteristics of the varistor ceramics samples were investigated by a DC parameter instrument for varistors.The results show that the ZnO-Bi2O3-based varistor ceramics with 0.3%Lu2O3(molar fraction)sintered at 950°C exhibit comparatively ideal comprehensive electrical properties.The XRD analysis of the samples shows the presence of ZnO,Bi-rich,spinel Zn7Sb2O12 and Lu2O3-based phases.展开更多
基金Project(2003AA332040) supported by the National High Technology Research and Development Program of China
摘要ZrO2-mullite nano-ceramics were fabricated by in-situ controlled crystallizing from SiO2-Al2O3-ZrO2 amorphous bulk. The thermal transformation sequences of the SiO2-Al2O3-ZrO2 amorphous bulk were investigated by X-ray diffraction, infrared spectrum, scanning electron microscope and differential scanning calorimetric. And the mechanical properties of the nano-ceramics were studied. The results show that the bulks are still in amorphous state at 900 ℃ and the t-ZrO2 forms at about 950 ℃ with a faint spinel-like phase which changes into mullite on further heating. ZrO2 and mullite become major phases at 1 100 ℃ and an amount of m-ZrO2 occur at the same time. The sample heated at 950 ℃ for 2 h and then at 1 100 ℃ for 1 h shows very dense and homogenous microstructure with ball-like grains in size of 20-50 nm. With the increase of crystallization temperature up to 1 350 ℃, the grains grow quickly and some grow into lath-shaped grains with major diameter of 5 μm. After two-step treatment the highest micro-hardness, flexural strength and fracture toughness of the samples are 13.72 GPa, 520 MPa and 5.13 MPa·m1/2, respectively.
摘要SiO2-Al2O3-ZrO2 glasses with different nucleating agents were crystallized under special processing schedule. The microstructure and mechanical properties of the glass-ceramics in SiO2-Al2O3-ZrO2 system were investigated by differential scanning calorimetry, scanning electron microscopy, X-ray diffraction and three-point bending method. The results show that ZrO2 is not an effective nucleating agent in SiO2-Al2O3-ZrO2 system, while TiO2 is effective for the separation of spinel, and P2O5 facilitates solubility of ZrO2 in glass and crystallization. The main crystalline phases of the glass-ceramics are spinel, anorthite and tetragonal zirconia. With the increase of ZrO2 content in the glass, glass-ceramics show higher bending strength (120MPa) than others.
摘要Through measuring the coefficient of linear expansion, the structure and properties of the Li2O-Al2O3-SiO2 low expansion glass ceramics containing B2O3 are studied by JR and XRD. It is shoutn that the IR method is efficient in the study of the glass-ceramics structure. There is a " Boron abnormality" in the system which has an important influence on the properties of the glass-ceramics.
基金Project(HIT.NSRIF.2010112)supported by the Fundamental Research Fund for the Central Universities,ChinaProjects(50902030,51021002)supported by the National Natural Science Foundation of China
摘要BNp/Al2O3-SiO2 system ceramic matrix composites with different volume fractions (10%-60%) of hexagonal BN particulates (BNp) were prepared by hot-press sintering technique. Phase components, microstructure, mechanical properties and plasma erosion resistance were also investigated. With the increase of h-BNp content, relative density and Vickers' hardness of the composite ceramics decrease, while the flexural strength, elastic modulus and fracture toughness increase and then decrease. The plasma erosion resistance linearly deteriorated with the increase of BNp content which is mainly determined by the density, crystal structure and atomic number of the elements.
基金Project(2007AA03Z0455) supported by the National High Technology Research and Development Program of ChinaProject(BE2010194) supported by Science&Technology Pillar Program of Jiangsu Province, China+1 种基金Project(KF201103) supported by the State Key Laboratory of New Ceramic and Fine Processing, Tsinghua University, ChinaProject supported by the Priority Academic Development of Jiangsu Higher Education Institutions, China
摘要CaO-B203-SiO2 (CBS) glass powders are prepared by conventional glass melting method at different melting temperatures whose properties and microstructures are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is found that there are SiO2 and some unknown phases in CBS glass melting liquid from 1 300 ℃ to 1 500 ℃ and the amount of these phases decreases with the increase of the melting temperature. The CBS glass melted at 1 450 ℃ could be sintered from 830 ℃ to 930 ℃ and the bulk densities of the samples are all higher than 2.4 g/cm^3. From the points of the properties and energy conservation, the melting temperature of 1 450 ℃ is the optimal melting temperature. The glass ceramic sintered at 850 ℃ exhibits better dielectric properties: er=6.33, tan6=2.2×10^-3 at 10 GHz, and the major phases of the samples are CaSiO3, CaB2O4 and SiO2.
基金supported by the National Natural Science Foundation of China (Grant No. 60578041)the Sciences and Technology Commission Foundation of Shanghai,China (Grant No. 08520707300)the Key Basic Research Project of Science and Technology of Shanghai (Grant No. 09JC1406500)
摘要This paper reports that polycrystalline (α-Al2O3:C ceramics are fabricated by conventional ceramics process. The excitation, emission spectra, thermoluminescence (TL) and optical stimulated luminescence (OSL) of α-Al2O3:C polycrystalline ceramics are investigated. There exists 410nm maximum emission peak which is caused by recombination of an electron with F+ centre to produce an excited F centre. The samples show three clear TL glow peaks at 405, 493 and 610 K. The attenuation constant of exponentially decaying fast component (τ1) and slow component(τ2) of OSL curve are 8.43s and 41.73s, respectively. Those fluorescence and thermoluminescence characteristics are similar with α-Al2O3:C crystal.
基金This project was sponsored by "863" Project (No. 2003AA322020)
摘要The Al2O3 abrasion-resistant ceramics is successfully prepared by using waste aluminum sludge as the main raw material with the addition of a little clay, talc and barium carbonate. The crystal structure and microstructure of ceramic are characterized by means of XRD, SEM, etc., and the physical and mechanical properties are also tested. The results show that besides the phase of corundum, a little mullite, Mg-Al spinel and hyalophane phases also exist in the product. These phases are produced via reaction in-situ, which can inhibit the overgrowth of Al2O3 grain in grain boundary, and improve the integral property of the material.
基金Project supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20133718120009)the Natural Science Foundation of Shandong Provence,China(Grant Nos.ZR2013FQ002 and ZR2014FQ006)+2 种基金the China Postdoctoral Science Foundation(Grant No.2014M551935)the Qingdao Municipality Postdoctoral Science Foundation,Chinathe Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents,China(Grant Nos.2013RCJJ042 and 2014RCJJ052)
摘要In this paper, we present a compact low-temperature co-fired ceramic(LTCC) dual-band antenna by using the electromagnetic coupling effect concept for global positioning system(GPS) and universal mobile telecommunication system(UMTS) applications. The overall dimension of the antenna is 8.6 mm × 13.0 mm × 1.1 mm. It consists of double meander lines and a via hole line. The top meander line operates at the upper band, and the bottom radiating patch is designed for the lower band. The via-hole line is employed to connect the double meander lines. Because of the effect of the coupled line,total dimension of the proposed antenna is greatly reduced. With the 2.5: voltage standing wave ratio(VSWR) impedance bandwidth definition, the lower and upper bands have the bandwidths of 110 MHz and 150 MHz, respectively. The proposed antenna is successfully designed, simulated, and analyzed by a high frequency structure simulator(HFSS). And the antenna is manufactured by using the 0.95Zn2SiO4-0.05 CaTiO3ceramics(εr = 7.1, tanδ = 0.00038) that is prepared by ourselves. The results show that the antenna is compact, efficient, and of near omnidirectional radiation pattern.
摘要微纳米α-Al2O3是一种重要的功能材料,因其优异的硬度、耐磨性、耐腐蚀性和高热稳定性,在表面涂层领域得到了广泛应用。随着微纳米技术的发展,微纳米级α-Al2O3作为添加剂在各涂层体系中的应用得到了深入研究,显示出其能够显著改善涂层性能的潜力。微纳米α-Al2O3颗粒具有较大的比表面积和表面活性,能够增强涂层的机械性能,如硬度和耐磨性,同时提高涂层的耐腐蚀性和耐高温性能。微纳米α-Al2O3也是一种极优良的改性材料,其与有机硅烷、树脂等材料复合改性,既能大幅提升转化膜的应用效果,对其稳定性和耐候性也有较大的促进作用。在金属表面涂层、陶瓷涂层以及复合材料涂层中,微纳米α-Al2O3添加剂被广泛用于提高涂层的使用寿命和稳定性。此外,它在电子器件、航天航空和汽车工业等高技术领域也展现了广阔的应用前景。未来,随着表面技术的发展,微纳米α-Al2O3无铬钝化领域的市场应用将大幅增长,与其他功能性材料的协同作用和复合材料开发也将成为研究的重点。Micro-nano α-Al2O3 is an important functional material, because of its excellent hardness, wear resistance, corrosion resistance and high thermal stability, has been widely used in the field of surface coating. With the development of micro-nano technology, the application of micro-nano α-Al2O3 as an additive in various coating systems has been deeply studied, showing its potential to significantly improve coating properties. Micro-nano α-Al2O3 particles have a large specific surface area and surface activity, which can enhance the mechanical properties of the coating, such as hardness and wear resistance, while improving the corrosion resistance and high temperature resistance of the coating. Micro-nano α-Al2O3 is also an excellent modified material, and its composite modification with organosilane, resin and other materials can greatly improve the application effect of conversion film, and also has a greater role in promoting its stability and weather resistance. In metal surface coatings, ceramic coatings and composite coatings, micro-nano α-Al2O3 additives are widely used to improve the service life and stability of coatings. In addition, it also shows broad application prospects in high-tech fields such as electronic devices, aerospace and automotive industries. In the future, with the development of surface technology, the market application of micro-nano α-Al2O3 chromium-free passivation will grow significantly, and the synergy with other functional materials and the development of composite materials will also become the focus of research.
摘要Ba 3Zn Z Co 2 Z Fe 24 O 41 /SiO 2 ( Z varies from 0.0 to 1.2 in step of 0.4) microcrystalline glass ceramics were prepared by citrate sol gel process at 1 200 ℃ in the system of BaO Fe 2O 3 CoO ZnO SiO 2. The samples were characterized by X ray diffraction (XRD) and scanning electron microscopy (SEM). The complex dielectric constant and complex permeability of Ba 3Zn Z Co 2 Z Fe 24 O 41 /SiO 2 microcrystalline glass ceramics were measured in the range of 0.16.0 GHz by transmissioneflection coaxial line method. The natural resonance phenomenon was observed in μ ″ spectra for all the Ba 3Zn Z Co 2 Z Fe 24 O 41 /SiO 2 microcrystalline glass ceramics, which was closely affected by the substitution of Zn 2+ ion.
基金financial supported by the National Natural Science Foundation of China(Nos.51672064 and U1435206).
摘要Al2O3f/Al2O3 ceramic matrix composites(CMC)are promising candidate materials of blades and combustor liners of future gas turbines in light of their higher temperature capability,higher environmental stability and oxidizing-free capacity[1–3].Nevertheless,grain growth,sintering and creep deformation at high operation temperatures are still serious problems for Al2O3f/Al2O3 ceramic matrix composites,which can lead to a reduction in the strength and damage tolerance[2].Moreover,Al2O3 can be corroded by the high temperature water vapor in combustion environments and yields volatile products,such as Al(OH)3[4].Consequently,environmental barrier coatings(EBCs)are necessary for Al2O3f/Al2O3 ceramic matrix composites,which can protect Al2O3f/Al2O3 CMC from high temperature and flowing combustion gas corrosion and thus increase the high temperature capability and the service life of components.
基金supported by the National Natural Science Foundation of China(21377018)the Natural Science Foundation of Liaoning Province of China(2013020116)the Fundamental Research Funds for the Central Universities(DUT15ZD240)~~
摘要A ternary composite of TiO2 and a SiO2-Al2O3 aerogel with good photocatalytic activity was prepared by a simple sol-gel method with TiO2 nanoparticles and SiO2-Al2O3 aerogels derived from industrial fly ash.The structural features of the TiO2/SiO2-Al2O3 aerogel composite were investigated by X-ray powder diffraction,Fourier transform infrared spectroscopy,transmission electron microscopy,gas adsorption measurements and diffuse reflectance UV-visible spectroscopy.The optimal conditions for photocatalytic degradation of 2-sec-butyl-4,6-dinitrophenol(DNBP],included an initial DNBP concentration of 0.167 mmol/L at pH = 4.86 with a catalyst concentration of 6 g/L,under visible light irradiation for 5 h.A plausible mechanism is proposed for the photocatalytic degradation of DNBP.Our composite showed higher photocatalytic activity for DNBP degradation than that of pure TiO2.This indicates that this material can serve as an efficient photocatalyst for degradation of hazardous organic pollutants in wastewater.
基金Project(50902061)supported by the National Natural Science Foundation of ChinaProject(2011-22)supported by the State Key Laboratory of Inorganic Synthesis and Preparative Chemistry of Jilin University,China+3 种基金Project(20100471380)supported by the China Postdoctoral Science FoundationProject(J50102)supported by the Leading Academic Discipline Program of Shanghai Municipal Education Commission,ChinaProject(10KJD430002)supported by the Universities Natural Science Research Program of Jiangsu Province,ChinaProject(2010002)supported by the Jiangsu University Undergraduate Practice-Innovation Training Program,China
摘要Lu2O3-doped ZnO-Bi2O3-based varistor ceramics samples were prepared by a conventional mixed oxide route and sintered at temperatures in the range of 900-1 000°C,and the microstructures of the varistor ceramics samples were characterized by X-ray diffractometry(XRD)and scanning electron microscopy(SEM);at the same time,the electrical properties and V-I characteristics of the varistor ceramics samples were investigated by a DC parameter instrument for varistors.The results show that the ZnO-Bi2O3-based varistor ceramics with 0.3%Lu2O3(molar fraction)sintered at 950°C exhibit comparatively ideal comprehensive electrical properties.The XRD analysis of the samples shows the presence of ZnO,Bi-rich,spinel Zn7Sb2O12 and Lu2O3-based phases.