Zeolite FAU composites with a macro/meso-microporous hierarchical structure were hydrothermally synthesized using macro-mesoporous γ-Al_2O_3 monolith as the substrate by means of the liquid crystallization directing...Zeolite FAU composites with a macro/meso-microporous hierarchical structure were hydrothermally synthesized using macro-mesoporous γ-Al_2O_3 monolith as the substrate by means of the liquid crystallization directing agent(LCDA) induced method. No template was needed throughout the synthesis processes. The structure and porosity of zeolite composites were analyzed by means of X-ray powder diffraction(XRD), scanning electron microscopy(SEM) and N_2adsorption-desorption isotherms. The results showed that the supported zeolite composites with varied zeolitic crystalline phases and different morphologies can be obtained by adjusting the crystallization parameters, such as the crystallization temperature, the composition and the alkalinity of the precursor solution. The presence of LCDA was defined as a determinant for synthesizing the zeolite composites. The mechanisms for formation of the hierarchically porous FAU zeolite composites in the LCDA induced synthesis process were discussed. The resulting monolithic zeolite with a trimodal-porous hierarchical structure shows potential applicability where facile diffusion is required.展开更多
The bonding of β″-Al2O3 and pyrex glass to A1 matrix composites by anodic bonding process is achieved. The microstructure of the bonded interface and the joining mechanisms are analyzed with scanning electron micros...The bonding of β″-Al2O3 and pyrex glass to A1 matrix composites by anodic bonding process is achieved. The microstructure of the bonded interface and the joining mechanisms are analyzed with scanning electron microscope （SEM）, energy dispersive X-ray fluorescence spectrometer （EDX）. It is observed that the bonding region across the interface consists of the metal layer, oxide transitional layer and the ceramic layer, with the transitional layer composed of surface region and sub-surface region. The bonding process can mainly be categorized into anodic bonding process and solid state diffusing process. The pile-up of the ions and its drift in the interface area are the main reasons for anode oxidation and joining of the interface. The temperature, voltage and the drift ions in the ceramic or glass during the bonding process are the essential conditions to solid state diffusing and oxide bonding at the interface. The voltages, temperature, pressure as well as the surface state are the main factors that influence the anodic bonding.展开更多
A γ-Al2O3 particles reinforced Al-Si alloy matrix composite was fabricated by adding NH4Al（SO4）2 to molten aluminum alloy. TEM observation shows that in-situ γ-Al2O3 particles are generally spherical and uniformly...A γ-Al2O3 particles reinforced Al-Si alloy matrix composite was fabricated by adding NH4Al（SO4）2 to molten aluminum alloy. TEM observation shows that in-situ γ-Al2O3 particles are generally spherical and uniformly distributed in the matrix. The results of dry sliding wear tests show that the wear resistance of the composites increases with increasing mass fraction, and the volume loss is considerably lesser than that of the matrix and is lesser than that of the composites by adding γ-Al2O3 particles directly.展开更多
A solid acid catalyst has been prepared by grafting Boron trifluoride on mesoporous molecular sieve MCM 41 and characterized by XRD and FTIR techniques. The XRD and FTIR results indicated that the BF 3·Et 2O inte...A solid acid catalyst has been prepared by grafting Boron trifluoride on mesoporous molecular sieve MCM 41 and characterized by XRD and FTIR techniques. The XRD and FTIR results indicated that the BF 3·Et 2O interlocks with the silicon groups of MCM 41 surface to form strong solid acid. The solid acid catalyst would effectively promote the opening of epichlorohydrin with isobutanol to form 1 isobutoxy 3 chloropropanol, and showed a nice activity and selectivity.展开更多
TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis（SHS） method with reductive process from B2O3-TiO2-AI system. X-ray diffraction（XRD） and scanning electron microscopy（SEM...TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis（SHS） method with reductive process from B2O3-TiO2-AI system. X-ray diffraction（XRD） and scanning electron microscopy（SEM） analyses show the presence of TiB2 and Al2O3 only in the composite powders produced by SHS. The powders are uniform and free-agglomerate. Transmission electron microscopy （TEM） and high resolution electron microscopy （HREM） observation of microstructure of the composite powders indicate that the interfaces of the TiB2-Al2O3 bond well, without any interfacial reaction products. It is proposed that the good interfacial bonding of the composite powders can be resulted from the TiB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers.展开更多
SiCp/Al2O3-Al composites were synthesized by means of direct metal oxidation method. The composition and microstructures of the composites were investigated using X-ray diffraction （XRD）, scanning electron microsco...SiCp/Al2O3-Al composites were synthesized by means of direct metal oxidation method. The composition and microstructures of the composites were investigated using X-ray diffraction （XRD）, scanning electron microscopy （SEM） and metallurgical microscope. The effects of technical parameters on the properties of the product were analyzed. The results indicate that the composite possesses a dense microstructure, composed of three interpenetrated phases. Of them, SiO2 layer prohibits the powdering of the composites; Mg promotes the wetting and infiltration of the system and Si restricts the interfacial reaction while improving the wetting ability between reinforcement and matrix.展开更多
Metal matrix composites (MMCs) are gaining widespread recognition in numerous technological fields owing to its superior mechanical properties when compared with conventional metals/alloys. The aluminium based hybrid ...Metal matrix composites (MMCs) are gaining widespread recognition in numerous technological fields owing to its superior mechanical properties when compared with conventional metals/alloys. The aluminium based hybrid composites are increasingly being used in the transport, aerospace, marine, automobile and mineral processing industries, owing to the improved strength, stiffness and wear resistance properties. In the present research work, the composites were prepared using the liquid metallurgy technique, in which 2 - 10 weight percentage of Al2O3 particulates and 1 weight percentage of Graphite were dispersed in the base Al6061 alloy. The Casted hybrid composites were subjected to machining process to prepare the specimens according to ASTM standards. Then, the prepared specimens are subjected for assessing the Microstructure followed by its Mechanical behaviors such as, Hardness, Tensile strength, Compressive strength respectively. The microstructure analysis confirms that homogenous distribution of Al2O3 and Gr in the Al6061 matrix alloy and there was a momentous enhancement in decisive tensile strength, compressive strength and hardness properties of the hybrid composite. However, a substantial increase in the compressive strength was noticed in graphite reinforced composites as the graphite content was increased and there was a significant diminution in hardness coupled with monotonic increases in the ductility. Further, the ultimate tensile strength and compressive strength of the composite was noticed;thus the outcome of the study will provide explicit rationalizations for these observable facts. Therefore, the proposed way out in the study can provide ample of approaches to minimize the existing problem by employing this newer hybrid composites.展开更多
A series of 3.0Mo/MCM-22-Al2O3 catalysts with γ-Al2O3 contents in the range of 0-100 wt% were prepared and applied in the metathesis reaction of ethene and butene-2. Addition of γ-Al2O3did not affect the structure o...A series of 3.0Mo/MCM-22-Al2O3 catalysts with γ-Al2O3 contents in the range of 0-100 wt% were prepared and applied in the metathesis reaction of ethene and butene-2. Addition of γ-Al2O3did not affect the structure of MCM-22 zeolite as evidenced by XRD and N2 adsorption measurements. It was deduced from TPR experiments that γ-Al2O3 phase favored the formation of polymolybdate or multilayered Mo oxide, while more Al2（MoO4）3 species were generated over MCM-22 zeolites. Alumina content in the support was directly related to the metathesis activity of ethene and butene-2 to propene. Mo species with higher valence （Mo6＋or Mo5＋） contributed more to the excellent performance of catalyst than metallic Mo. The best catalyst activity and stability was obtained over 3.0Mo/（MCM-22-30%Al2O3） under the reaction condition of 1.0 MPa and 125℃ using N2 as the pretreatment gas.展开更多
Advanced technology has put an increasing demand on the composite materials, particularly more in the areas of dynamic structures. Among the several types of aluminum alloys being used, Al5000 series are widely used i...Advanced technology has put an increasing demand on the composite materials, particularly more in the areas of dynamic structures. Among the several types of aluminum alloys being used, Al5000 series are widely used in marine and aerospace applications due to their superior corrosion resistance, excellent formability and good welding characteristics. Al5083, a non-heat treatable high Mg-Al wrought alloy, is extensively used for the marine applications. Hence, an attempt has been made in the proposed work to study the effects of Graphite (Gr) and Aluminium oxide (Al2O3) on aluminum hybrid composites involving both hard and soft reinforcements on wear and corrosion properties. The synthesis of hybrid metal matrix composite used in the present study has been carried out by stir casting method. The effects of reinforcement, time duration and particle size on prepared samples of composites have been studied on slurry erosive wear. The static and accelerated corrosion tests have been performed and the microhardness of the developed composites was also investigated. The experimental results on Al5083-Al2O3-Gr hybrid composites revealed that the addition of reinforcement improves the hardness and reduces corrosion and wear rates.展开更多
CaO-SiO2-Al2O3-MgO-Fex O slag occurs in the production process of Corex ironmaking technology. Most of its metallurgical properties, especially the phosphorus property, are different from the slag produced from blast ...CaO-SiO2-Al2O3-MgO-Fex O slag occurs in the production process of Corex ironmaking technology. Most of its metallurgical properties, especially the phosphorus property, are different from the slag produced from blast furnace or converter. In order to explore the dephosphorization ability of CaO-SiO2-Al2O3-MgO-Fex O slag, its phosphorus capacity was measured at 1673 K by gas-slag-metal equilibrium technique. An iron crucible was used as the reaction vessel, Ag alloy with 0.2 % P was used as the metal phase which equilibrated with CaO-SiO2-Al2O3-MgO-Fex O slag, and a constant flow of CO-CO2-N2 gas was used to provide oxygen partial pressure in the experi- ment. The effects of MgO, Fex O and basicity on slag phosphorus capacity were investigated by single factor test. The results show that the phosphorus capacity rises firstly and then decreases with increasing MgO content under the condition of basicity 1.3, Fe2 O content of 20% and A12 03 content of 12%. The phosphorus value reaches maximum as the MgO content is 8%. When the basicity of slag is 1.1, MgO content is 10%, and Al2O3 is 12%, the phos- phorus capacity increases with the increase of Fe, O content. The phosphorus capacity rises linearly when the basicity is increased from 1.1 to 1. 5.展开更多
TWC-equipped exhausts are widely used in gasoline-fueled vehicles to meet stringent emission regulations. The main components in TWCs are precious metals such as palladium (Pd), platinum (Pt), and rhodium (Rh) as the ...TWC-equipped exhausts are widely used in gasoline-fueled vehicles to meet stringent emission regulations. The main components in TWCs are precious metals such as palladium (Pd), platinum (Pt), and rhodium (Rh) as the active component, and inorganic oxides such as γ-alumina (Al 2 O 3 ), ceria (CeO 2 ), zirconia (ZrO 2 ) and ceria-zirconia (CeO 2-ZrO 2 ) are used as the support. Interaction of precious metals and support plays an important role in the thermal stability and catalytic performance of TWCs. The support can improve the dispersion of precious metals and suppress the sintering of precious metals at high temperature. In the same, precious metals can also enhance the redox performance and oxygen storage capacity of support. This paper reviews the reaction phenomenon and mechanism of precious metals (Pt, Pd, Rh) and supports such as Al 2 O 3 , CeO 2-based composite oxides.展开更多
基金the financial support from the National Natural Science Foundation of China(No.20973022 and No.11472048)the State Key Laboratory of Catalytic Materials and Reaction Engineering(RIPP,SINOPEC)(Serial No.33600000-14-ZC0607-0006)
文摘Zeolite FAU composites with a macro/meso-microporous hierarchical structure were hydrothermally synthesized using macro-mesoporous γ-Al_2O_3 monolith as the substrate by means of the liquid crystallization directing agent(LCDA) induced method. No template was needed throughout the synthesis processes. The structure and porosity of zeolite composites were analyzed by means of X-ray powder diffraction(XRD), scanning electron microscopy(SEM) and N_2adsorption-desorption isotherms. The results showed that the supported zeolite composites with varied zeolitic crystalline phases and different morphologies can be obtained by adjusting the crystallization parameters, such as the crystallization temperature, the composition and the alkalinity of the precursor solution. The presence of LCDA was defined as a determinant for synthesizing the zeolite composites. The mechanisms for formation of the hierarchically porous FAU zeolite composites in the LCDA induced synthesis process were discussed. The resulting monolithic zeolite with a trimodal-porous hierarchical structure shows potential applicability where facile diffusion is required.
基金National Natural Science Foundation of China (No.50375105,No. 50671070)
文摘The bonding of β″-Al2O3 and pyrex glass to A1 matrix composites by anodic bonding process is achieved. The microstructure of the bonded interface and the joining mechanisms are analyzed with scanning electron microscope （SEM）, energy dispersive X-ray fluorescence spectrometer （EDX）. It is observed that the bonding region across the interface consists of the metal layer, oxide transitional layer and the ceramic layer, with the transitional layer composed of surface region and sub-surface region. The bonding process can mainly be categorized into anodic bonding process and solid state diffusing process. The pile-up of the ions and its drift in the interface area are the main reasons for anode oxidation and joining of the interface. The temperature, voltage and the drift ions in the ceramic or glass during the bonding process are the essential conditions to solid state diffusing and oxide bonding at the interface. The voltages, temperature, pressure as well as the surface state are the main factors that influence the anodic bonding.
基金the Key Project of Ministry of Education of China (No.105055).
文摘A γ-Al2O3 particles reinforced Al-Si alloy matrix composite was fabricated by adding NH4Al（SO4）2 to molten aluminum alloy. TEM observation shows that in-situ γ-Al2O3 particles are generally spherical and uniformly distributed in the matrix. The results of dry sliding wear tests show that the wear resistance of the composites increases with increasing mass fraction, and the volume loss is considerably lesser than that of the matrix and is lesser than that of the composites by adding γ-Al2O3 particles directly.
文摘A solid acid catalyst has been prepared by grafting Boron trifluoride on mesoporous molecular sieve MCM 41 and characterized by XRD and FTIR techniques. The XRD and FTIR results indicated that the BF 3·Et 2O interlocks with the silicon groups of MCM 41 surface to form strong solid acid. The solid acid catalyst would effectively promote the opening of epichlorohydrin with isobutanol to form 1 isobutoxy 3 chloropropanol, and showed a nice activity and selectivity.
文摘TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis（SHS） method with reductive process from B2O3-TiO2-AI system. X-ray diffraction（XRD） and scanning electron microscopy（SEM） analyses show the presence of TiB2 and Al2O3 only in the composite powders produced by SHS. The powders are uniform and free-agglomerate. Transmission electron microscopy （TEM） and high resolution electron microscopy （HREM） observation of microstructure of the composite powders indicate that the interfaces of the TiB2-Al2O3 bond well, without any interfacial reaction products. It is proposed that the good interfacial bonding of the composite powders can be resulted from the TiB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers.
基金National Natural Science Foundation of China (50372037)Scientific Research Foundations of Shaanxi University of Science and Technology (SUST-B14)
文摘SiCp/Al2O3-Al composites were synthesized by means of direct metal oxidation method. The composition and microstructures of the composites were investigated using X-ray diffraction （XRD）, scanning electron microscopy （SEM） and metallurgical microscope. The effects of technical parameters on the properties of the product were analyzed. The results indicate that the composite possesses a dense microstructure, composed of three interpenetrated phases. Of them, SiO2 layer prohibits the powdering of the composites; Mg promotes the wetting and infiltration of the system and Si restricts the interfacial reaction while improving the wetting ability between reinforcement and matrix.
文摘Metal matrix composites (MMCs) are gaining widespread recognition in numerous technological fields owing to its superior mechanical properties when compared with conventional metals/alloys. The aluminium based hybrid composites are increasingly being used in the transport, aerospace, marine, automobile and mineral processing industries, owing to the improved strength, stiffness and wear resistance properties. In the present research work, the composites were prepared using the liquid metallurgy technique, in which 2 - 10 weight percentage of Al2O3 particulates and 1 weight percentage of Graphite were dispersed in the base Al6061 alloy. The Casted hybrid composites were subjected to machining process to prepare the specimens according to ASTM standards. Then, the prepared specimens are subjected for assessing the Microstructure followed by its Mechanical behaviors such as, Hardness, Tensile strength, Compressive strength respectively. The microstructure analysis confirms that homogenous distribution of Al2O3 and Gr in the Al6061 matrix alloy and there was a momentous enhancement in decisive tensile strength, compressive strength and hardness properties of the hybrid composite. However, a substantial increase in the compressive strength was noticed in graphite reinforced composites as the graphite content was increased and there was a significant diminution in hardness coupled with monotonic increases in the ductility. Further, the ultimate tensile strength and compressive strength of the composite was noticed;thus the outcome of the study will provide explicit rationalizations for these observable facts. Therefore, the proposed way out in the study can provide ample of approaches to minimize the existing problem by employing this newer hybrid composites.
基金supported by the National Natural Science Foundation of China (Grant No. 20903088 and 20773120)the Ministry of Science and Technology of China through the National Key Project of Fundamental Research (Grant No.2009CB623507)
文摘A series of 3.0Mo/MCM-22-Al2O3 catalysts with γ-Al2O3 contents in the range of 0-100 wt% were prepared and applied in the metathesis reaction of ethene and butene-2. Addition of γ-Al2O3did not affect the structure of MCM-22 zeolite as evidenced by XRD and N2 adsorption measurements. It was deduced from TPR experiments that γ-Al2O3 phase favored the formation of polymolybdate or multilayered Mo oxide, while more Al2（MoO4）3 species were generated over MCM-22 zeolites. Alumina content in the support was directly related to the metathesis activity of ethene and butene-2 to propene. Mo species with higher valence （Mo6＋or Mo5＋） contributed more to the excellent performance of catalyst than metallic Mo. The best catalyst activity and stability was obtained over 3.0Mo/（MCM-22-30%Al2O3） under the reaction condition of 1.0 MPa and 125℃ using N2 as the pretreatment gas.
文摘Advanced technology has put an increasing demand on the composite materials, particularly more in the areas of dynamic structures. Among the several types of aluminum alloys being used, Al5000 series are widely used in marine and aerospace applications due to their superior corrosion resistance, excellent formability and good welding characteristics. Al5083, a non-heat treatable high Mg-Al wrought alloy, is extensively used for the marine applications. Hence, an attempt has been made in the proposed work to study the effects of Graphite (Gr) and Aluminium oxide (Al2O3) on aluminum hybrid composites involving both hard and soft reinforcements on wear and corrosion properties. The synthesis of hybrid metal matrix composite used in the present study has been carried out by stir casting method. The effects of reinforcement, time duration and particle size on prepared samples of composites have been studied on slurry erosive wear. The static and accelerated corrosion tests have been performed and the microhardness of the developed composites was also investigated. The experimental results on Al5083-Al2O3-Gr hybrid composites revealed that the addition of reinforcement improves the hardness and reduces corrosion and wear rates.
基金Item Sponsored by the State Key Program of National Natural Science Foundation of China(U1360205)National Natural Science Foundation of China(51174074)
文摘CaO-SiO2-Al2O3-MgO-Fex O slag occurs in the production process of Corex ironmaking technology. Most of its metallurgical properties, especially the phosphorus property, are different from the slag produced from blast furnace or converter. In order to explore the dephosphorization ability of CaO-SiO2-Al2O3-MgO-Fex O slag, its phosphorus capacity was measured at 1673 K by gas-slag-metal equilibrium technique. An iron crucible was used as the reaction vessel, Ag alloy with 0.2 % P was used as the metal phase which equilibrated with CaO-SiO2-Al2O3-MgO-Fex O slag, and a constant flow of CO-CO2-N2 gas was used to provide oxygen partial pressure in the experi- ment. The effects of MgO, Fex O and basicity on slag phosphorus capacity were investigated by single factor test. The results show that the phosphorus capacity rises firstly and then decreases with increasing MgO content under the condition of basicity 1.3, Fe2 O content of 20% and A12 03 content of 12%. The phosphorus value reaches maximum as the MgO content is 8%. When the basicity of slag is 1.1, MgO content is 10%, and Al2O3 is 12%, the phos- phorus capacity increases with the increase of Fe, O content. The phosphorus capacity rises linearly when the basicity is increased from 1.1 to 1. 5.
基金National Science technology Support Plan Projects"(2012BAE06B00)
文摘TWC-equipped exhausts are widely used in gasoline-fueled vehicles to meet stringent emission regulations. The main components in TWCs are precious metals such as palladium (Pd), platinum (Pt), and rhodium (Rh) as the active component, and inorganic oxides such as γ-alumina (Al 2 O 3 ), ceria (CeO 2 ), zirconia (ZrO 2 ) and ceria-zirconia (CeO 2-ZrO 2 ) are used as the support. Interaction of precious metals and support plays an important role in the thermal stability and catalytic performance of TWCs. The support can improve the dispersion of precious metals and suppress the sintering of precious metals at high temperature. In the same, precious metals can also enhance the redox performance and oxygen storage capacity of support. This paper reviews the reaction phenomenon and mechanism of precious metals (Pt, Pd, Rh) and supports such as Al 2 O 3 , CeO 2-based composite oxides.
