The influence of the certain specific vacuum pre-oxidation process on the phase transformation of thermally-grown oxides（TGO） was studied.The CoCrAlY high temperature corrosion resistance coatings were produced onto...The influence of the certain specific vacuum pre-oxidation process on the phase transformation of thermally-grown oxides（TGO） was studied.The CoCrAlY high temperature corrosion resistance coatings were produced onto the nickel-based superalloy substrate by high velocity oxygen fuel（HVOF）.It suggests that the TGO usually consists of a great number of chromium oxides,cobalt oxides and spinel oxides besides alumina during the initial period of the high temperature oxidation if the specimens are not subjected to the appropriate vacuum pre-oxidation process.Furthermore,the amount of alumina is strongly dependent on the partial pressure of oxygen;while the CoCr2O4 spinel oxides are usually formed under the conditions of higher partial pressure of oxygen during the initial period and the lower partial pressure of oxygen during the subsequent period of the isothermal oxidation.After the appropriate vacuum pre-oxidation process,the TGO is mainly composed of alumina that contains lower Y element,while alumina that contains higher Y element sporadically distributes,and the spinel oxides cannot be found.After a longer period of the isothermal oxidation,a small amount of porous CoCr2O4 and the chrome oxide sporadically distribute near the continuous alumina.Additionally,after the appropriate vacuum pre-oxidation process,the TGO growth rate is relatively slow.展开更多
Within the OECD/NEA Benchmarking of Thermal-Hydraulic Loop Models for Lead-Alloy Cooled Advanced Nuclear Energy Systems （LACANES）, the Institute for Neutron Physics and Reactor Technology takes part in the validatio...Within the OECD/NEA Benchmarking of Thermal-Hydraulic Loop Models for Lead-Alloy Cooled Advanced Nuclear Energy Systems （LACANES）, the Institute for Neutron Physics and Reactor Technology takes part in the validation process of system codes and the characterization of the thermal-hydraulic behavior of an experimental loop operated with liquid lead-bismuth-eutectics. To confirm the calculations, the results were compared to experimental data obtained from the HELIOS facility at the Seoul National University and to the results of other benchmark participants. The comparison showed that the calculations are within measurement tolerance but nevertheless discrepancies among the participants exist. The pressure drop estimation is determined by a variety of empirical correlations for the friction and the form loss coefficients. Hence, uncertainty and sensitivity measures were applied to find out which parameter is more relevant for the overall pressure drop. In the frame of this investigation, the system code TRACE and the software system for uncertainty and sensitivity, SUSA, were used. The results show that the total pressure drop varies between -30 and ＋15% related to the reference case.展开更多
基金Project supported the by State Key Laboratory of Internal Combustion Engines of Tianjin University,ChinaProject(51507077)supported by the National Natural Science Foundation of China+1 种基金Project(15KJB470005)supported by the Natural Science Research of Higher Education Institutions of Jiangsu Province,ChinaProjects(YKJ201308,QKJB201401)supported by Nanjing Institute of Technology,China
文摘The influence of the certain specific vacuum pre-oxidation process on the phase transformation of thermally-grown oxides（TGO） was studied.The CoCrAlY high temperature corrosion resistance coatings were produced onto the nickel-based superalloy substrate by high velocity oxygen fuel（HVOF）.It suggests that the TGO usually consists of a great number of chromium oxides,cobalt oxides and spinel oxides besides alumina during the initial period of the high temperature oxidation if the specimens are not subjected to the appropriate vacuum pre-oxidation process.Furthermore,the amount of alumina is strongly dependent on the partial pressure of oxygen;while the CoCr2O4 spinel oxides are usually formed under the conditions of higher partial pressure of oxygen during the initial period and the lower partial pressure of oxygen during the subsequent period of the isothermal oxidation.After the appropriate vacuum pre-oxidation process,the TGO is mainly composed of alumina that contains lower Y element,while alumina that contains higher Y element sporadically distributes,and the spinel oxides cannot be found.After a longer period of the isothermal oxidation,a small amount of porous CoCr2O4 and the chrome oxide sporadically distribute near the continuous alumina.Additionally,after the appropriate vacuum pre-oxidation process,the TGO growth rate is relatively slow.
文摘Within the OECD/NEA Benchmarking of Thermal-Hydraulic Loop Models for Lead-Alloy Cooled Advanced Nuclear Energy Systems （LACANES）, the Institute for Neutron Physics and Reactor Technology takes part in the validation process of system codes and the characterization of the thermal-hydraulic behavior of an experimental loop operated with liquid lead-bismuth-eutectics. To confirm the calculations, the results were compared to experimental data obtained from the HELIOS facility at the Seoul National University and to the results of other benchmark participants. The comparison showed that the calculations are within measurement tolerance but nevertheless discrepancies among the participants exist. The pressure drop estimation is determined by a variety of empirical correlations for the friction and the form loss coefficients. Hence, uncertainty and sensitivity measures were applied to find out which parameter is more relevant for the overall pressure drop. In the frame of this investigation, the system code TRACE and the software system for uncertainty and sensitivity, SUSA, were used. The results show that the total pressure drop varies between -30 and ＋15% related to the reference case.
