The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Jonatha D Haftel - One of the best experts on this subject based on the ideXlab platform.
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slow crack growth behavior of zirconia toughened Alumina and Alumina using the dynamic fatigue indentation technique
Journal of the American Ceramic Society, 2011Co-Authors: Subramania Ramalingam, Edwi R Fulle, Ivar E. Reimanis, Jonatha D HaftelAbstract:A dynamic fatigue indentation technique was used to determine the slow crack growth (SCG) parameters of a medical-grade platelet-reinforced zirconia-toughened Alumina and two different fine-grain Aluminas: one a common grade of nominal 99.5% purity, and the other a high-purity (99.94%) medical-grade Alumina. Fatigue tests in bending were performed at various loading rates with precracked Vickers indentations in 100% relative humidity conditions. Inert strength tests were performed in dry nitrogen. The dynamic fatigue analysis accounts for the presence of the indentation. The SCG power law exponent was found to be 36, 65, and 93 for the 99.5% Alumina, the 99.94% Alumina, and the zirconia-toughened Alumina, respectively. The presence of glassy phase likely increases SCG in the 99.5% Alumina compared with the higher purity Alumina. The zirconia-toughened Alumina exhibits a relatively steep R curve that forms due to two toughening mechanisms: platelet reinforcement and transformation toughening. It is apparent that neither of mechanisms degrades significantly due to moisture-assisted SCG.
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Slow Crack Growth Behavior of Zirconia‐Toughened Alumina and Alumina Using the Dynamic Fatigue Indentation Technique
Journal of the American Ceramic Society, 2010Co-Authors: Subramanian Ramalingam, Edwin R. Fuller, Ivar E. Reimanis, Jonatha D HaftelAbstract:A dynamic fatigue indentation technique was used to determine the slow crack growth (SCG) parameters of a medical-grade platelet-reinforced zirconia-toughened Alumina and two different fine-grain Aluminas: one a common grade of nominal 99.5% purity, and the other a high-purity (99.94%) medical-grade Alumina. Fatigue tests in bending were performed at various loading rates with precracked Vickers indentations in 100% relative humidity conditions. Inert strength tests were performed in dry nitrogen. The dynamic fatigue analysis accounts for the presence of the indentation. The SCG power law exponent was found to be 36, 65, and 93 for the 99.5% Alumina, the 99.94% Alumina, and the zirconia-toughened Alumina, respectively. The presence of glassy phase likely increases SCG in the 99.5% Alumina compared with the higher purity Alumina. The zirconia-toughened Alumina exhibits a relatively steep R curve that forms due to two toughening mechanisms: platelet reinforcement and transformation toughening. It is apparent that neither of mechanisms degrades significantly due to moisture-assisted SCG.
Banghao Chen - One of the best experts on this subject based on the ideXlab platform.
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Surface Alumina species on modified titanium dioxide: A solid-state (27)Al MAS and 3QMAS NMR investigation of catalyst supports.
Solid state nuclear magnetic resonance, 2010Co-Authors: Edward W Hagaman, Banghao Chen, Jian Jiao, Zhen MaAbstract:(27)Al MAS and 3QMAS NMR have been used to study Al(2)O(3)/TiO(2) catalyst supports synthesized via excess-solution impregnation and surface sol-gel methods. Temperature and Alumina loading level strongly affect chemical states of aluminum oxide species observed. Surface cations, Al(H2O)6(3+), a surface Alumina monolayer, and disordered transitional Aluminas (multilayers) and alpha-Alumina, coexist on the TiO(2) surface. Chemical shift and quadrupole coupling constants are reported for the major species identified in 3QMAS experiments. Gold particle catalysts prepared from supports calcined at 500 degrees C have optimum catalytic activity in CO oxidation, and smallest gold particle size for supports, which show maximum monolayer type octahedral Alumina on the titania surface.
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surface Alumina species on modified titanium dioxide a solid state 27al mas and 3qmas nmr investigation of catalyst supports
Solid State Nuclear Magnetic Resonance, 2010Co-Authors: Edward W Hagaman, Jian Jiao, Banghao ChenAbstract:Abstract 27Al MAS and 3QMAS NMR have been used to study Al2O3/TiO2 catalyst supports synthesized via excess-solution impregnation and surface sol–gel methods. Temperature and Alumina loading level strongly affect chemical states of aluminum oxide species observed. Surface cations, Al ( H 2 O ) 6 3 + , a surface Alumina monolayer, and disordered transitional Aluminas (multilayers) and α-Alumina, coexist on the TiO2 surface. Chemical shift and quadrupole coupling constants are reported for the major species identified in 3QMAS experiments. Gold particle catalysts prepared from supports calcined at 500 °C have optimum catalytic activity in CO oxidation, and smallest gold particle size for supports, which show maximum monolayer type octahedral Alumina on the titania surface.
Edward W Hagaman - One of the best experts on this subject based on the ideXlab platform.
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Surface Alumina species on modified titanium dioxide: A solid-state (27)Al MAS and 3QMAS NMR investigation of catalyst supports.
Solid state nuclear magnetic resonance, 2010Co-Authors: Edward W Hagaman, Banghao Chen, Jian Jiao, Zhen MaAbstract:(27)Al MAS and 3QMAS NMR have been used to study Al(2)O(3)/TiO(2) catalyst supports synthesized via excess-solution impregnation and surface sol-gel methods. Temperature and Alumina loading level strongly affect chemical states of aluminum oxide species observed. Surface cations, Al(H2O)6(3+), a surface Alumina monolayer, and disordered transitional Aluminas (multilayers) and alpha-Alumina, coexist on the TiO(2) surface. Chemical shift and quadrupole coupling constants are reported for the major species identified in 3QMAS experiments. Gold particle catalysts prepared from supports calcined at 500 degrees C have optimum catalytic activity in CO oxidation, and smallest gold particle size for supports, which show maximum monolayer type octahedral Alumina on the titania surface.
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surface Alumina species on modified titanium dioxide a solid state 27al mas and 3qmas nmr investigation of catalyst supports
Solid State Nuclear Magnetic Resonance, 2010Co-Authors: Edward W Hagaman, Jian Jiao, Banghao ChenAbstract:Abstract 27Al MAS and 3QMAS NMR have been used to study Al2O3/TiO2 catalyst supports synthesized via excess-solution impregnation and surface sol–gel methods. Temperature and Alumina loading level strongly affect chemical states of aluminum oxide species observed. Surface cations, Al ( H 2 O ) 6 3 + , a surface Alumina monolayer, and disordered transitional Aluminas (multilayers) and α-Alumina, coexist on the TiO2 surface. Chemical shift and quadrupole coupling constants are reported for the major species identified in 3QMAS experiments. Gold particle catalysts prepared from supports calcined at 500 °C have optimum catalytic activity in CO oxidation, and smallest gold particle size for supports, which show maximum monolayer type octahedral Alumina on the titania surface.
Mianyin Bian - One of the best experts on this subject based on the ideXlab platform.
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Comparison of effect of La-modification on the thermostabilities of Alumina and Alumina-supported Pd catalysts prepared from different Alumina sources
Applied Catalysis B: Environmental, 2001Co-Authors: Zhuxian Yang, Xiaoyin Chen, Guoxin Niu, Yong Liu, Mianyin BianAbstract:Abstract The thermostability of La-free and La-modified Aluminas derived from different Alumina sources including pseudo-boehmite, aluminum sulfate, aluminum nitrate, and aluminum chloride have been studied by characterizations of BET specific surface area (BET) and X-ray powder diffraction (XRD). Further, the activity and thermal durability of monolith-supported Pd catalysts using above different Alumina as washcoats for simultaneously catalytic oxidation of C3H8, C3H6 and CO have been investigated using continuous flowing reaction. The experimental results show that the oxidation activity over the Alumina-supported Pd catalysts does not keep in agreement with the surface area of Aluminas derived from four aluminum sources. Lanthanum modification improves the activity of all catalysts calcined over 1000°C for simultaneously catalytic oxidation of C3H8, C3H6 and CO. Alumina source plays a role on the activity and thermostability of Alumina and Alumina-supported Pd catalysts. The experimental results show that pseudo boehmite is the best Alumina source used for catalytic oxidation at high temperature over 1000°C.
Ivar E. Reimanis - One of the best experts on this subject based on the ideXlab platform.
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slow crack growth behavior of zirconia toughened Alumina and Alumina using the dynamic fatigue indentation technique
Journal of the American Ceramic Society, 2011Co-Authors: Subramania Ramalingam, Edwi R Fulle, Ivar E. Reimanis, Jonatha D HaftelAbstract:A dynamic fatigue indentation technique was used to determine the slow crack growth (SCG) parameters of a medical-grade platelet-reinforced zirconia-toughened Alumina and two different fine-grain Aluminas: one a common grade of nominal 99.5% purity, and the other a high-purity (99.94%) medical-grade Alumina. Fatigue tests in bending were performed at various loading rates with precracked Vickers indentations in 100% relative humidity conditions. Inert strength tests were performed in dry nitrogen. The dynamic fatigue analysis accounts for the presence of the indentation. The SCG power law exponent was found to be 36, 65, and 93 for the 99.5% Alumina, the 99.94% Alumina, and the zirconia-toughened Alumina, respectively. The presence of glassy phase likely increases SCG in the 99.5% Alumina compared with the higher purity Alumina. The zirconia-toughened Alumina exhibits a relatively steep R curve that forms due to two toughening mechanisms: platelet reinforcement and transformation toughening. It is apparent that neither of mechanisms degrades significantly due to moisture-assisted SCG.
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Slow Crack Growth Behavior of Zirconia‐Toughened Alumina and Alumina Using the Dynamic Fatigue Indentation Technique
Journal of the American Ceramic Society, 2010Co-Authors: Subramanian Ramalingam, Edwin R. Fuller, Ivar E. Reimanis, Jonatha D HaftelAbstract:A dynamic fatigue indentation technique was used to determine the slow crack growth (SCG) parameters of a medical-grade platelet-reinforced zirconia-toughened Alumina and two different fine-grain Aluminas: one a common grade of nominal 99.5% purity, and the other a high-purity (99.94%) medical-grade Alumina. Fatigue tests in bending were performed at various loading rates with precracked Vickers indentations in 100% relative humidity conditions. Inert strength tests were performed in dry nitrogen. The dynamic fatigue analysis accounts for the presence of the indentation. The SCG power law exponent was found to be 36, 65, and 93 for the 99.5% Alumina, the 99.94% Alumina, and the zirconia-toughened Alumina, respectively. The presence of glassy phase likely increases SCG in the 99.5% Alumina compared with the higher purity Alumina. The zirconia-toughened Alumina exhibits a relatively steep R curve that forms due to two toughening mechanisms: platelet reinforcement and transformation toughening. It is apparent that neither of mechanisms degrades significantly due to moisture-assisted SCG.
