To clarify the effect of SnO2 particle size on the arc erosion behavior of AgSnO2 contact material, Ag?4%SnO2 (mass fraction) contact materials with different sizes of SnO2 particles were fabricated by powder metallur...To clarify the effect of SnO2 particle size on the arc erosion behavior of AgSnO2 contact material, Ag?4%SnO2 (mass fraction) contact materials with different sizes of SnO2 particles were fabricated by powder metallurgy. The microstructure of Ag?4%SnO2 contact materials was characterized, and the relative density, hardness and electrical conductivity were measured. The arc erosion of Ag?4%SnO2 contact materials was tested, the arc duration and mass loss before and after arc erosion were determined, the surface morphologies and compositions of Ag?4%SnO2 contact materials after arc erosion were characterized, and the arc erosion mechanism of AgSnO2 contact materials was discussed. The results show that fine SnO2 particle is beneficial for the improvement of the relative density and hardness, but decreases the electrical conductivity. With the decrease of SnO2 particle size, Ag?4%SnO2contact material presents shorter arc duration, less mass loss, larger erosion area and shallower arc erosion pits.展开更多
The electrical contact and mechanical performances of Ag-SnO_(2) contact materials are often improved by additives,especially Cu and its oxides.To reveal the improvement mechanism of metal additive,the effects of Cu n...The electrical contact and mechanical performances of Ag-SnO_(2) contact materials are often improved by additives,especially Cu and its oxides.To reveal the improvement mechanism of metal additive,the effects of Cu nanoparticles on the interface strength and failure behavior of the Ag-SnO_(2) contact materials are investigated by numerical simulations and experiments.Three-dimensional representative volume element(RVE)models for the Ag-SnO_(2) materials without and with Cu nanoparticles are established,and the cohesive zone model is used to simulate the interface debonding process.The results show that the stress−strain relationships and failure modes predicted by the simulation agree well with the experimental ones.The adhesion strengths of the Ag/SnO_(2) and Ag/Cu interfaces are respectively predicted to be 100 and 450 MPa through the inverse method.It is found that the stress concentration around the SnO_(2) phase is the primary reason for the interface debonding,which leads to the failure of Ag-SnO_(2) contact material.The addition of Cu particles not only improves the interface strength,but also effectively suppresses the initiation and propagation of cracks.The results have an reference value for improving the processability of Ag based contact materials.展开更多
SnO_(2)has been extensively used in the detection of various gases.As a gas sensing material,SnO_(2)has excellent physical-chemical properties,high reliability,and short adsorption-desorption time.The application of t...SnO_(2)has been extensively used in the detection of various gases.As a gas sensing material,SnO_(2)has excellent physical-chemical properties,high reliability,and short adsorption-desorption time.The application of the traditional SnO_(2)gas sensor is limited due to its higher work-temperature,low gas response,and poor selectivity.Nanomaterials can significantly impact gas-sensitive properties due to the quantum size,surface,and small size effects of nanomaterials.By applying nanotechnology to the preparation of SnO_(2),the SnO_(2)nanomaterial-based sensors could show better performance,which greatly expands the application of SnO_(2)gas sensors.In this review,the preparation method of the SnO_(2)nanostructure,the types of gas detected,and the improvements of SnO_(2)gas-sensing performances via elemental modification are introduced as well as the future development of SnO_(2)is discussed.展开更多
Yttrium-doped SnO2 powders were successfully synthesized by solution co-precipitation method and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The sensitivity of sensors based on...Yttrium-doped SnO2 powders were successfully synthesized by solution co-precipitation method and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The sensitivity of sensors based on Y-doped SnO2 and SnO2 nanocrystals were investigated comparatively. The results indicated that Y-doped SnO2 was with the result of enhancement of sensitivity and selectivity to ethanol and reduction of sensitivity to other gas components. The enhancements of selectivity and sensitivity could be contributed to for two reasons. The first is that rare metal yttrium has a high alkalescence and good catalysis, and the second is that the nanosized crystallite and large specific surface area of Y-doped SnO2 is advantageous for gas-diffusion control as well as an increase in active sites for gas detection.展开更多
According to the principle that fiber-like arrangement of reinforcing particles SnO2 paralleling to the direction of current is propitious to the electrical and mechanical performance of the electrical contact materia...According to the principle that fiber-like arrangement of reinforcing particles SnO2 paralleling to the direction of current is propitious to the electrical and mechanical performance of the electrical contact materials, we proposed and reported a novel precursor route used to prepare Ag/SnO,. electrical contact material with fiber- like arrangement of reinforcing nanoparticles. The mechanism for the formation of fiber-like arrangement of rein- forcing nanoparticles in Ag/SnO2 electrical contact material was also discussed. The as-prepared samples were char- acterized by means of scanning electron microscope （SEM）, optical microscope （OM）, energy-dispersive X-ray spectroscopy （EDX）, MHV2000 microhardness test, and double bridge tester. The analysis showed that the as-prepared Ag/SnO,, electrical contact material with fiber-like arrangement of reinforcing nanoparticles exhibits a high elongation of 24 %, a particularly low electrical resistivity of 2.08 μΩ. cm, and low arcing energy, and thus has considerable technical, economical and environmental benefits.展开更多
基金Project(51274163)supported by the National Natural Science Foundation of ChinaProject(13JS076)supported by the Key Laboratory Research Program of Shaanxi Province,China+1 种基金Project(2012KCT-25)supported by the Pivot Innovation Team of Shaanxi Electrical Materials and Infiltration Technique,ChinaProject(2011HBSZS009)supported by the Special Foundation of Key Disciplines,China
文摘To clarify the effect of SnO2 particle size on the arc erosion behavior of AgSnO2 contact material, Ag?4%SnO2 (mass fraction) contact materials with different sizes of SnO2 particles were fabricated by powder metallurgy. The microstructure of Ag?4%SnO2 contact materials was characterized, and the relative density, hardness and electrical conductivity were measured. The arc erosion of Ag?4%SnO2 contact materials was tested, the arc duration and mass loss before and after arc erosion were determined, the surface morphologies and compositions of Ag?4%SnO2 contact materials after arc erosion were characterized, and the arc erosion mechanism of AgSnO2 contact materials was discussed. The results show that fine SnO2 particle is beneficial for the improvement of the relative density and hardness, but decreases the electrical conductivity. With the decrease of SnO2 particle size, Ag?4%SnO2contact material presents shorter arc duration, less mass loss, larger erosion area and shallower arc erosion pits.
基金Projects(11872257,11572358)supported by the National Natural Science Foundation of ChinaProject(ZD2018075)supported by the Hebei Provincial Education Department,China。
文摘The electrical contact and mechanical performances of Ag-SnO_(2) contact materials are often improved by additives,especially Cu and its oxides.To reveal the improvement mechanism of metal additive,the effects of Cu nanoparticles on the interface strength and failure behavior of the Ag-SnO_(2) contact materials are investigated by numerical simulations and experiments.Three-dimensional representative volume element(RVE)models for the Ag-SnO_(2) materials without and with Cu nanoparticles are established,and the cohesive zone model is used to simulate the interface debonding process.The results show that the stress−strain relationships and failure modes predicted by the simulation agree well with the experimental ones.The adhesion strengths of the Ag/SnO_(2) and Ag/Cu interfaces are respectively predicted to be 100 and 450 MPa through the inverse method.It is found that the stress concentration around the SnO_(2) phase is the primary reason for the interface debonding,which leads to the failure of Ag-SnO_(2) contact material.The addition of Cu particles not only improves the interface strength,but also effectively suppresses the initiation and propagation of cracks.The results have an reference value for improving the processability of Ag based contact materials.
基金supported by National Natural Science Foundation of China(No.61761047 and 41876055)the Department of Science and Technology of Yunnan Province via the Key Project for the Science and Technology(Grant No.2017FA025)Program for Innovative Research Team(in Science and Technology)in University of Yunnan Province。
文摘SnO_(2)has been extensively used in the detection of various gases.As a gas sensing material,SnO_(2)has excellent physical-chemical properties,high reliability,and short adsorption-desorption time.The application of the traditional SnO_(2)gas sensor is limited due to its higher work-temperature,low gas response,and poor selectivity.Nanomaterials can significantly impact gas-sensitive properties due to the quantum size,surface,and small size effects of nanomaterials.By applying nanotechnology to the preparation of SnO_(2),the SnO_(2)nanomaterial-based sensors could show better performance,which greatly expands the application of SnO_(2)gas sensors.In this review,the preparation method of the SnO_(2)nanostructure,the types of gas detected,and the improvements of SnO_(2)gas-sensing performances via elemental modification are introduced as well as the future development of SnO_(2)is discussed.
基金NSFC (20471055)Henan Outstanding Youth Science Fund (0612002700)
文摘Yttrium-doped SnO2 powders were successfully synthesized by solution co-precipitation method and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The sensitivity of sensors based on Y-doped SnO2 and SnO2 nanocrystals were investigated comparatively. The results indicated that Y-doped SnO2 was with the result of enhancement of sensitivity and selectivity to ethanol and reduction of sensitivity to other gas components. The enhancements of selectivity and sensitivity could be contributed to for two reasons. The first is that rare metal yttrium has a high alkalescence and good catalysis, and the second is that the nanosized crystallite and large specific surface area of Y-doped SnO2 is advantageous for gas-diffusion control as well as an increase in active sites for gas detection.
基金National Major Scientific&Technological Achievement Transformation Project
文摘According to the principle that fiber-like arrangement of reinforcing particles SnO2 paralleling to the direction of current is propitious to the electrical and mechanical performance of the electrical contact materials, we proposed and reported a novel precursor route used to prepare Ag/SnO,. electrical contact material with fiber- like arrangement of reinforcing nanoparticles. The mechanism for the formation of fiber-like arrangement of rein- forcing nanoparticles in Ag/SnO2 electrical contact material was also discussed. The as-prepared samples were char- acterized by means of scanning electron microscope （SEM）, optical microscope （OM）, energy-dispersive X-ray spectroscopy （EDX）, MHV2000 microhardness test, and double bridge tester. The analysis showed that the as-prepared Ag/SnO,, electrical contact material with fiber-like arrangement of reinforcing nanoparticles exhibits a high elongation of 24 %, a particularly low electrical resistivity of 2.08 μΩ. cm, and low arcing energy, and thus has considerable technical, economical and environmental benefits.
