UN燃料具有铀密度高、熔点高、热导率高、热膨胀系数低、辐照稳定性好等优点，是未来空间核电源、核火箭、快堆和ADS的重要候选燃料。本文采用金属铀粉与氮气在300～400℃直接发生化合反应，制得单相U2 N3粉末。粒度为38.3μm的 U2 N3...UN燃料具有铀密度高、熔点高、热导率高、热膨胀系数低、辐照稳定性好等优点，是未来空间核电源、核火箭、快堆和ADS的重要候选燃料。本文采用金属铀粉与氮气在300～400℃直接发生化合反应，制得单相U2 N3粉末。粒度为38.3μm的 U2 N3粉末在1600℃真空热压烧结，制得相对密度为93.5％、存在少量金属铀相的U N陶瓷；而18.1μm的U2 N3粉末在1550℃真空热压烧结，制得相对密度为96.1％、不残留金属铀相的 U N陶瓷，U与N的总质量分数为99.57％，每个金属杂质含量均低于50μg/g ，氧含量为1048μg/g ，碳含量为502μg/g。U2 N3在1027℃以上将会完全分解成UN ，UN在1627℃以上也会发生分解。展开更多
This paper is a report on the development of a convenient approach to fabricating a very efficient hybrid photoelectrocatalyst for water splitting.This photoelectrocatalyst consists of nickel-cobalt layered double hyd...This paper is a report on the development of a convenient approach to fabricating a very efficient hybrid photoelectrocatalyst for water splitting.This photoelectrocatalyst consists of nickel-cobalt layered double hydroxide as the core,cadmium sulfide as the shell,and nitrogen,hence NiCo-LDH@CdS-N.For the electrocatalytic activity to be improved,the H_(2) and O_(2) binding energy needs to be weakened.The interstitial nitrogen doping on NiCo-LDH@CdS can increase electrocatalytic activity to a great extent.NiCoLDH@CdS nanoparticles are obtained by subjecting to nitriding the NiCo-LDH@CdS electrode coated with polyvinylpyrrolidone nanosheets.This electrode has a large specific surface area,allows fast transfer of electrons,and exhibits long-term stability.The experimental results presented in this paper reveal that interstitial nitrogen doping largely reduces H_(2) and O_(2) binding energy and lowers the activation barrier for the formation and splitting of water.展开更多
Nitriding process of medium carbon ferromanganese was carried out in the solid state, on lab and bench scale at temperature range 1023-1323 K using different nitrogen and hydrogen pressures. The influence of H2/N2 gas...Nitriding process of medium carbon ferromanganese was carried out in the solid state, on lab and bench scale at temperature range 1023-1323 K using different nitrogen and hydrogen pressures. The influence of H2/N2 gas ratio, temperature and time on nitriding process of fine (-2 mm) medium carbon ferromanganese were investigated. Nitrogen content, in weight percent ranging from 2.1 to 9.7 could be obtained. The optimum temperature and time of nitriding process was found to be 1223 K and 21.6 ks respectively. The results showed that nitrogen content is mainly depending on time and temperature of nitriding process. The comparison between results of lab and bench scale, at optimum conditions, showed good coincidence. At optimum conditions;1223 K, 21.6 ks and at 2/8 of H2/N2, nitrogen content of fine medium carbon ferromanganese was 9.5%.展开更多
Investigation of some kinetics aspects of the reaction between nitrogen and medium carbon ferromanganese （MC-FeMn） was made. Nitriding process of fine medium carbon ferromanganese was carried out at temperature rang...Investigation of some kinetics aspects of the reaction between nitrogen and medium carbon ferromanganese （MC-FeMn） was made. Nitriding process of fine medium carbon ferromanganese was carried out at temperature ranging from 973 to 1 223 K and time up to 480 min. Nitriding was carried out under nitrogen and hydrogen gas pressures. At temperature of 573 K, hydrogen gas was injected with pressure of about 0.2 MPa followed by injection of nitrogen gas up to 1.2 MPa. Sample mass was 35 g, nitrided in cylindrical chamber with 34 mm in inner diameter and 1 200 mm in length. The change in nitrogen pressure was taken as an indication for nitrogen pickup. The mass gain i.e. nitrogen pickup in kilograms per surface area （m2） was determined by time at different temperatures. Nitriding rate constants were calculated and the activation energy of nitriding process was derived from Arrhenius equation. The nitriding rate constant was found to be increased by increasing temperature of the reaction. The activation energy of nitriding process of fine medium carbon ferromanganese at time ranging up to 28 800 s is around 140 kJ/mol. It was found that the rate controlling step of the nitriding process of MC-FeMn is diffusion mechanism.展开更多
文摘This paper is a report on the development of a convenient approach to fabricating a very efficient hybrid photoelectrocatalyst for water splitting.This photoelectrocatalyst consists of nickel-cobalt layered double hydroxide as the core,cadmium sulfide as the shell,and nitrogen,hence NiCo-LDH@CdS-N.For the electrocatalytic activity to be improved,the H_(2) and O_(2) binding energy needs to be weakened.The interstitial nitrogen doping on NiCo-LDH@CdS can increase electrocatalytic activity to a great extent.NiCoLDH@CdS nanoparticles are obtained by subjecting to nitriding the NiCo-LDH@CdS electrode coated with polyvinylpyrrolidone nanosheets.This electrode has a large specific surface area,allows fast transfer of electrons,and exhibits long-term stability.The experimental results presented in this paper reveal that interstitial nitrogen doping largely reduces H_(2) and O_(2) binding energy and lowers the activation barrier for the formation and splitting of water.
文摘Nitriding process of medium carbon ferromanganese was carried out in the solid state, on lab and bench scale at temperature range 1023-1323 K using different nitrogen and hydrogen pressures. The influence of H2/N2 gas ratio, temperature and time on nitriding process of fine (-2 mm) medium carbon ferromanganese were investigated. Nitrogen content, in weight percent ranging from 2.1 to 9.7 could be obtained. The optimum temperature and time of nitriding process was found to be 1223 K and 21.6 ks respectively. The results showed that nitrogen content is mainly depending on time and temperature of nitriding process. The comparison between results of lab and bench scale, at optimum conditions, showed good coincidence. At optimum conditions;1223 K, 21.6 ks and at 2/8 of H2/N2, nitrogen content of fine medium carbon ferromanganese was 9.5%.
文摘Investigation of some kinetics aspects of the reaction between nitrogen and medium carbon ferromanganese （MC-FeMn） was made. Nitriding process of fine medium carbon ferromanganese was carried out at temperature ranging from 973 to 1 223 K and time up to 480 min. Nitriding was carried out under nitrogen and hydrogen gas pressures. At temperature of 573 K, hydrogen gas was injected with pressure of about 0.2 MPa followed by injection of nitrogen gas up to 1.2 MPa. Sample mass was 35 g, nitrided in cylindrical chamber with 34 mm in inner diameter and 1 200 mm in length. The change in nitrogen pressure was taken as an indication for nitrogen pickup. The mass gain i.e. nitrogen pickup in kilograms per surface area （m2） was determined by time at different temperatures. Nitriding rate constants were calculated and the activation energy of nitriding process was derived from Arrhenius equation. The nitriding rate constant was found to be increased by increasing temperature of the reaction. The activation energy of nitriding process of fine medium carbon ferromanganese at time ranging up to 28 800 s is around 140 kJ/mol. It was found that the rate controlling step of the nitriding process of MC-FeMn is diffusion mechanism.
