Underground coal gasification （UCG） is one of the clean technologies to collect heat energy and gases （hydrogen, methane, etc.） in an underground coal seam. It is necessary to further developing environ- mentally ...Underground coal gasification （UCG） is one of the clean technologies to collect heat energy and gases （hydrogen, methane, etc.） in an underground coal seam. It is necessary to further developing environ- mentally friendly UCG system construction. One of the most important UCG＇s problems is underground control of combustion area for efficient gas production, estimation of subsidence and gas leakage to the surface. For this objective, laboratory experiments were conducted according to the UCG model to iden- ti[y the process of combustion cavity development by monitoring the electrical resistivity activity on the coal samples to setup fundamental data for the technology engineering to evaluate combustion area. While burning coal specimens, that had been sampled from various coal deposits, electrical resistivity was monitored. Symmetric four electrodes system （ABMN） of direct and low-frequency current electric resistance method was used for laboratory resistivity measurement of rock samples. Made research and the results suggest that front-end of electro conductivity activity during heating and combusting of coal specimen depended on heating temperature. Combusting coal electro conductivity has compli- cated multistage type of change. Electrical resistivity method is expected to be a useful geophysical tool to for evaluation of combustion volume and its migration in the coal seam.展开更多
Ni-Ce0.8Sm.2O.9 （Ni-SDC） cermet was selected as anode material for reduced temperature （800℃） solid oxide fuel cells in this study. The influence of NiO powder fabrication methods for Ni-SDC cermets on the electr...Ni-Ce0.8Sm.2O.9 （Ni-SDC） cermet was selected as anode material for reduced temperature （800℃） solid oxide fuel cells in this study. The influence of NiO powder fabrication methods for Ni-SDC cermets on the electrode performance was investigated so that the result obtained can be applied to make high-quality anode. Three kinds of NiO powder were synthesized with a fourth kind being available in the market. Four types of anode precursors were fabricated with these NiO powders and Ce0.8Sm.2O.9 （SDC）, and then were reduced to anode wafers for sequencing measurement. The electrical conductivity of the anodes was measured and the effect ofmicrostructure was investigated. It was found that the anode electrical conductivity depends strongly on the NiO powder morphologies, microstructure of the cermet anode and particle sizes, which are decided by NiO powder preparation technique. The highest electrical conductivity is obtained for anode cermets with NiO powder synthesized by NiCO3-2Ni（OH）2-4H2O or Ni（NO3）2-6H2O decomposition technique.展开更多
According to the character of gain-frequency characteristic change of electromagnetic response to impact excitation it is possible to trace quality change of components adhesive contact in composite materials and to p...According to the character of gain-frequency characteristic change of electromagnetic response to impact excitation it is possible to trace quality change of components adhesive contact in composite materials and to predict the moment of its destruction.展开更多
In order to improve the properties of inert anode of NiFe2O4 spinel, some additive V2O5 was added to raw materials-powders of NiO and Fe2O3. The powders of NiO, Fe2O3 were mixed with slight amount of V2O5, then they a...In order to improve the properties of inert anode of NiFe2O4 spinel, some additive V2O5 was added to raw materials-powders of NiO and Fe2O3. The powders of NiO, Fe2O3 were mixed with slight amount of V2O5, then they are moulded and sintered at 1200℃ for 6h.The sintering mechanism of powders of NiO and Fe2O3 with some additive V2O5 was researched. The effect of V2O5 on density, electrical conductivity and corrosion resistance of inert anode of NiFe2O4 spinel was studied at the same time. The results show that the sintering mechanism for powders of NiO and Fe2O3 with some additive V2O5 is liquid-phase sintering. Additive V2O5 can increase the density of the samples, especially it improves the corrosion resistance of the samples remarkably. When the amount of V2O5 is 1.5%, the sample’s corrosion rate is 1/80 of that of sample without V2O5. But the electrical conductivity of the samples with V2O5 is lower than that of the sample without V2O5.展开更多
Lithium iron phosphate is a most promising cathode material for Li-ion batteries（LIB）. But the key barrier limiting its application is extremely low electronic conductivity. Meanwhile the low electron conductivity c...Lithium iron phosphate is a most promising cathode material for Li-ion batteries（LIB）. But the key barrier limiting its application is extremely low electronic conductivity. Meanwhile the low electron conductivity can be improved by preparing LiFePO4 with carbon modified. LiFePO4/C was synthesized by high temperature solid-state reaction using iron （II） oxalate, ammonium di-hydrogen phosphate and lithium carbonate with a kind of organic compound （CR） that can be dissolved in the dispersant （ethanol） as carbon sources added to the synthetic precursor in this paper. The samples were characterized by X-ray diffraction, scanning electron microscope observations, charge/discharge test, cyclic voltammetry and carbon analysis. It was believed that the synthesized LiFePO4/C with perfect olivine structure by X-ray diffraction. The carbon brought about two advantages: （i） an optimized particle size of LiFePO4, and （ii） increasing the electronic conductivity and Li+ diffusivity. The cathode material could demonstrate a charge/discharge flat voltage of 3.4V （Vs Li+/Li）. Especially the active material with 20% organic added according to the final product of LiFePO4 showed very good electrochemical performance reaching about initial 162.0 mAh/g specific capacity at 0.1C rate and could also keep excellent discharge capacity even at 3C rate （510 mA/g） current and good cycle performance. The carbon content in the final production was only 5.29%（mass fraction）.展开更多
基金provided by the Ministry of EducationScience of Russian Federation (No. P1679),Far Eastern Federal University
文摘Underground coal gasification （UCG） is one of the clean technologies to collect heat energy and gases （hydrogen, methane, etc.） in an underground coal seam. It is necessary to further developing environ- mentally friendly UCG system construction. One of the most important UCG＇s problems is underground control of combustion area for efficient gas production, estimation of subsidence and gas leakage to the surface. For this objective, laboratory experiments were conducted according to the UCG model to iden- ti[y the process of combustion cavity development by monitoring the electrical resistivity activity on the coal samples to setup fundamental data for the technology engineering to evaluate combustion area. While burning coal specimens, that had been sampled from various coal deposits, electrical resistivity was monitored. Symmetric four electrodes system （ABMN） of direct and low-frequency current electric resistance method was used for laboratory resistivity measurement of rock samples. Made research and the results suggest that front-end of electro conductivity activity during heating and combusting of coal specimen depended on heating temperature. Combusting coal electro conductivity has compli- cated multistage type of change. Electrical resistivity method is expected to be a useful geophysical tool to for evaluation of combustion volume and its migration in the coal seam.
文摘Ni-Ce0.8Sm.2O.9 （Ni-SDC） cermet was selected as anode material for reduced temperature （800℃） solid oxide fuel cells in this study. The influence of NiO powder fabrication methods for Ni-SDC cermets on the electrode performance was investigated so that the result obtained can be applied to make high-quality anode. Three kinds of NiO powder were synthesized with a fourth kind being available in the market. Four types of anode precursors were fabricated with these NiO powders and Ce0.8Sm.2O.9 （SDC）, and then were reduced to anode wafers for sequencing measurement. The electrical conductivity of the anodes was measured and the effect ofmicrostructure was investigated. It was found that the anode electrical conductivity depends strongly on the NiO powder morphologies, microstructure of the cermet anode and particle sizes, which are decided by NiO powder preparation technique. The highest electrical conductivity is obtained for anode cermets with NiO powder synthesized by NiCO3-2Ni（OH）2-4H2O or Ni（NO3）2-6H2O decomposition technique.
文摘According to the character of gain-frequency characteristic change of electromagnetic response to impact excitation it is possible to trace quality change of components adhesive contact in composite materials and to predict the moment of its destruction.
文摘In order to improve the properties of inert anode of NiFe2O4 spinel, some additive V2O5 was added to raw materials-powders of NiO and Fe2O3. The powders of NiO, Fe2O3 were mixed with slight amount of V2O5, then they are moulded and sintered at 1200℃ for 6h.The sintering mechanism of powders of NiO and Fe2O3 with some additive V2O5 was researched. The effect of V2O5 on density, electrical conductivity and corrosion resistance of inert anode of NiFe2O4 spinel was studied at the same time. The results show that the sintering mechanism for powders of NiO and Fe2O3 with some additive V2O5 is liquid-phase sintering. Additive V2O5 can increase the density of the samples, especially it improves the corrosion resistance of the samples remarkably. When the amount of V2O5 is 1.5%, the sample’s corrosion rate is 1/80 of that of sample without V2O5. But the electrical conductivity of the samples with V2O5 is lower than that of the sample without V2O5.
文摘Lithium iron phosphate is a most promising cathode material for Li-ion batteries（LIB）. But the key barrier limiting its application is extremely low electronic conductivity. Meanwhile the low electron conductivity can be improved by preparing LiFePO4 with carbon modified. LiFePO4/C was synthesized by high temperature solid-state reaction using iron （II） oxalate, ammonium di-hydrogen phosphate and lithium carbonate with a kind of organic compound （CR） that can be dissolved in the dispersant （ethanol） as carbon sources added to the synthetic precursor in this paper. The samples were characterized by X-ray diffraction, scanning electron microscope observations, charge/discharge test, cyclic voltammetry and carbon analysis. It was believed that the synthesized LiFePO4/C with perfect olivine structure by X-ray diffraction. The carbon brought about two advantages: （i） an optimized particle size of LiFePO4, and （ii） increasing the electronic conductivity and Li+ diffusivity. The cathode material could demonstrate a charge/discharge flat voltage of 3.4V （Vs Li+/Li）. Especially the active material with 20% organic added according to the final product of LiFePO4 showed very good electrochemical performance reaching about initial 162.0 mAh/g specific capacity at 0.1C rate and could also keep excellent discharge capacity even at 3C rate （510 mA/g） current and good cycle performance. The carbon content in the final production was only 5.29%（mass fraction）.
