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CPham V. H.; 倉田 正輝; 永江 勇二; 石橋 良*; 佐々木 政名*
Corrosion Science, 255, p.113098_1 - 113098_9, 2025/10
Being expected as materials for accident tolerant fuel cladding tube, oxidation behavior and kinetics of silicon carbide (SiC) under extreme conditions like severe accidents must be elucidated. In this study, oxidation tests of SiC at 1400-1600 C for 1-5 h, at atmospheric pressure, under two different flow rates of H
O/Ar gas mixture have been conducted to investigate the influence of steam flow rate on the formation of SiO scale and its subsequent volatilization. The oxidation tests were conducted via a newly developed test facility using laser as a heat source. Oxidation kinetics of SiC was evaluated via mass change of samples before and after the oxidation tests. Parabolic oxidation rate representative for SiO formation and linear volatilization rate reflecting its volatilization were calculated, based on these mass changes. The Arrhenius dependence of the parabolic oxidation and linear volatilization rate constants were then plotted. Results of this study indicated that SiC exhibits excellent performance under the conditions investigated. Steam flow rate has a significant influence on volatilization of SiO but has minor effects over its formation. Oxidation of SiC in steam at high temperature may follow mass gain or mass loss regime, depending on the steam flow rate. Two oxidation patterns were suggested and discussed. In the first oxidation pattern, the SiO formation is dominated over its volatilization. The second oxidation pattern (steady stage) is reached when the SiO formation rate is equivalent to its volatilization rate. Time to reach this steady stage was defined, based on the parabolic oxidation rate and linear volatilization rate.
倉田 正輝; Pham, V. H.; 永江 勇二
no journal, ,
Since the disaster at Fukushima Daiichi Nuclear Power Plant, development of accident tolerant fuel to manage severe accidents has been proposed. As temperature of fuel rods could reach to temperatures above 2000C during the accident, investigation of oxidation behavior at such temperatures for fuel claddings must be conducted. Nevertheless, there is no test facility capable for operating at such conditions. In this study, we developed a laser heating facility for steam oxidation of cladding materials at extreme temperatures. Main features of the facility are controlled environment, in situ observation, extreme fast heating and cooling rate and off gas analysis. As the heat is focused on the test sample only, the facility can be operated at temperatures above 2000C. Preliminary tests have been conducted for monolithic SiC at 1400-1800C for 1-7 h under 0.96 atm steam partial pressure. Results of the investigation showed that SiC underwent a mass loss which obeyed paralinear laws. Based on the mass change data, parabolic oxidation rate and linear volatilization rate of the process were obtained. The apparent activation energy of the oxidation process was calculated to be 96 kJmol 
. Bubbling phenomenon was observed on SiC sample surface at 1800C.
Pham, V. H.; 永江 勇二; 倉田 正輝; 石橋 良*; 山下 真一郎
no journal, ,
In this study, oxidation of SiC under various flow rates of steam was investigated at 1400C using laser heating. Results of the investigation indicated that the mass evolution of SiC underwent a mass gain with 0.1 g/min of steam flow rate. Whereas, the mass evolution experienced a mass loss with 3 g/min of steam. Based on the data of mass change under the investigated conditions, the parabolic and linear rate constants were calculated and reported.
