Using the results of physical and chemical researches and mechanical tests of the Pd-Au-Cu-Sn system alloys, a new palladium-based alloy has been chosen and studied in detail. It has a higher plasticity and a lower ha...Using the results of physical and chemical researches and mechanical tests of the Pd-Au-Cu-Sn system alloys, a new palladium-based alloy has been chosen and studied in detail. It has a higher plasticity and a lower hardness than the Palladent alloy, widely used in prosthetic dentistry: its hardness is lower than 300 MPa, and its specific elongation is 10%~14 %. At the same time, such important practical characteristics of the alloys as the strength of adhesion to ceramics and thermal expansion coefficient are almost similar.展开更多
Palladium-based alloy is a kind of material with a high glass forming ability and can be easily formed into an amorphous state. After an annealing process, it can also be maintained at a crystallized state. To study t...Palladium-based alloy is a kind of material with a high glass forming ability and can be easily formed into an amorphous state. After an annealing process, it can also be maintained at a crystallized state. To study the thermal and electrical transport properties of crystallized palladium-based alloys, the steady-state T-type method, standard four-probe method, and AC heating-DC detecting T-type method were used to measure the thermal conductivity, electrical conductivity, and Seebeck coeffi- cient of crystallized Pd4oNiloCu3oP2o and Pd43Nilo- Cu27P2o alloys respectively. The results show that compared to amorphous samples, the thermal conductivity and electrical conductivity of crystallized palladium-based alloys are significantly higher, while the Seebeck coeffi- cient is lower. The ratio of crystallized and amorphous thermal conductivity is higher for Pd43Ni10Cu27P2o alloy fiber which has a higher glass forming ability, while the ratio of electronic thermal conductivity almost remains constant for both alloy fibers. The results also show that the slope of electrical resistivity to temperature is a function of elemental composition for crystallized quaternary palla- dium-based alloy fibers. The sensitivity of thermal conductivity and electrical conductivity to the composition is high, while the correlation between Seebeck coefficient and composition is relatively weak.展开更多
Shear bands in the interior of Pd（79）Cu6Si（10）P5,Pd（79）Cu3Ag3Si（10）P5, and Pd（79）Cu4Au2Si（10）P5 bulk metallic glasses were investigated by optical microscopy（OM） and scanning electron microscopy（SEM）. ...Shear bands in the interior of Pd（79）Cu6Si（10）P5,Pd（79）Cu3Ag3Si（10）P5, and Pd（79）Cu4Au2Si（10）P5 bulk metallic glasses were investigated by optical microscopy（OM） and scanning electron microscopy（SEM）. No shear bands can be observed in the samples before etching. By etching in aqua regia solution, shear bands are found to be susceptible to preferential etching, and multiple etched bands could be observed. The thickness of the etched bands is about 1-7 μm. Therefore, the preferentially etched shear bands found in the study are called the ＂extended＂ shear bands.The ＂extended＂ shear bands can be divided into three classes according to their features： early, developing, and well-developed ＂extended＂ shear bands with thickness of about 1, 5, and 7 μm, respectively. The interface between the well-developed ＂extended＂ shear bands and the matrix is clearer than that of the others.展开更多
A nanocatalyst composed of 10wt% Pd supported on TiO2 was synthesized using one-step flame spray pyrolysis with a highly-quenched premixed stagnation flame.The as-prepared nanoparticles,having a mean diameter of appro...A nanocatalyst composed of 10wt% Pd supported on TiO2 was synthesized using one-step flame spray pyrolysis with a highly-quenched premixed stagnation flame.The as-prepared nanoparticles,having a mean diameter of approximately 10nm,were then subjected to isothermal oxidation and reduction in a fixed bed reactor.The potential roles of Pd and PdO as well as possible synergistic effects between these two active species were explored during methane conversion.The lowest light-off temperature T20 was obtained at a Pd ratio of 53% and this result can be reasonably explained based on a surface Pd-PdO site pair mechanism.Additionally,differences in the hysteresis behavior during methane oxidation were noted throughout a heating-cooling cycle over the temperature range of 200-600℃,such that the degree of hysteresis was strongly correlated with the Pd ratio.展开更多
文摘Using the results of physical and chemical researches and mechanical tests of the Pd-Au-Cu-Sn system alloys, a new palladium-based alloy has been chosen and studied in detail. It has a higher plasticity and a lower hardness than the Palladent alloy, widely used in prosthetic dentistry: its hardness is lower than 300 MPa, and its specific elongation is 10%~14 %. At the same time, such important practical characteristics of the alloys as the strength of adhesion to ceramics and thermal expansion coefficient are almost similar.
文摘Palladium-based alloy is a kind of material with a high glass forming ability and can be easily formed into an amorphous state. After an annealing process, it can also be maintained at a crystallized state. To study the thermal and electrical transport properties of crystallized palladium-based alloys, the steady-state T-type method, standard four-probe method, and AC heating-DC detecting T-type method were used to measure the thermal conductivity, electrical conductivity, and Seebeck coeffi- cient of crystallized Pd4oNiloCu3oP2o and Pd43Nilo- Cu27P2o alloys respectively. The results show that compared to amorphous samples, the thermal conductivity and electrical conductivity of crystallized palladium-based alloys are significantly higher, while the Seebeck coeffi- cient is lower. The ratio of crystallized and amorphous thermal conductivity is higher for Pd43Ni10Cu27P2o alloy fiber which has a higher glass forming ability, while the ratio of electronic thermal conductivity almost remains constant for both alloy fibers. The results also show that the slope of electrical resistivity to temperature is a function of elemental composition for crystallized quaternary palla- dium-based alloy fibers. The sensitivity of thermal conductivity and electrical conductivity to the composition is high, while the correlation between Seebeck coefficient and composition is relatively weak.
基金financially supported by the National Natural Science Foundation of China (Nos. 51101133 and 51101134)the Encouraging Foundation for Outstanding Youth Scientists of Shandong Province, China (No. BS2012CL036)the Shandong Provincial Natural Science Foundation, China (No. ZR2011EL025)
文摘Shear bands in the interior of Pd（79）Cu6Si（10）P5,Pd（79）Cu3Ag3Si（10）P5, and Pd（79）Cu4Au2Si（10）P5 bulk metallic glasses were investigated by optical microscopy（OM） and scanning electron microscopy（SEM）. No shear bands can be observed in the samples before etching. By etching in aqua regia solution, shear bands are found to be susceptible to preferential etching, and multiple etched bands could be observed. The thickness of the etched bands is about 1-7 μm. Therefore, the preferentially etched shear bands found in the study are called the ＂extended＂ shear bands.The ＂extended＂ shear bands can be divided into three classes according to their features： early, developing, and well-developed ＂extended＂ shear bands with thickness of about 1, 5, and 7 μm, respectively. The interface between the well-developed ＂extended＂ shear bands and the matrix is clearer than that of the others.
文摘A nanocatalyst composed of 10wt% Pd supported on TiO2 was synthesized using one-step flame spray pyrolysis with a highly-quenched premixed stagnation flame.The as-prepared nanoparticles,having a mean diameter of approximately 10nm,were then subjected to isothermal oxidation and reduction in a fixed bed reactor.The potential roles of Pd and PdO as well as possible synergistic effects between these two active species were explored during methane conversion.The lowest light-off temperature T20 was obtained at a Pd ratio of 53% and this result can be reasonably explained based on a surface Pd-PdO site pair mechanism.Additionally,differences in the hysteresis behavior during methane oxidation were noted throughout a heating-cooling cycle over the temperature range of 200-600℃,such that the degree of hysteresis was strongly correlated with the Pd ratio.
