Effects of microstructure on the oxidation behavior of A3 matrix‐grade graphite

Abstract

The oxidation behavior of matrix-grade graphite in air-or steam-ingress accident scenarios is of great interest for high-temperature gas reactors (HTGRs). In this study, the microstructures of two variants of matrix-grade graphite based on the German

AGR-5/6/7 Irradiation Disassembly and Metrology First Look

“…AGR-5/6/7 used matrix graphite similar to the A3-27 formulation, while the other AGR fuels used an A3-3 formulation. The main difference between A3-3 and A3-27 is the binder, which can cause different microstructure (Bratten et al 2021). Besides different matrix formulas, AGR-5/6/7 matrix has a higher matrix density (Marshall 2019b).…”

Effect of La2O3 content on the oxygen barrier ability of the HfB2‐SiC coating at 1973 K

“…The sealing and deactivation capability of the generated glass against oxygen diffusion is another oxygen barrier core in the passivated oxidation period. For evaluating the deactivation effect of La 2 O 3 over the HfB 2 -SiC coating, the inert factors (α m ) are calculated according to Equation (6). After the addition of La 2 O 3 , the inert factor values of all specimens decrease by 84.57% (HSL5), 39.86% (HSL10), and where a s is the structure factor and a m is the inert factor, m p,j , m s,j , and m c,j are the unit area mass change at the jth weighing for carbon matrix, standard, and coated specimens respectively; m p,0 , m s,0 , and m c,0 correspond to the preliminary mass of their specimens, j denotes the number of weighing times and n = 10.…”

“…Carbon materials are appealing lightweight, high‐strength thermal structural materials used in aerospace equipment components due to their low density, outstanding high‐temperature strength, low coefficient of thermal expansion (CTE), and superior heat shock resistance 1–7 . Nevertheless, the high oxygen sensitivity of carbon materials renders them vulnerable to catastrophic oxidation at high temperatures and aerobic settings over 723 K, resulting in weight loss by gasification, 8,9 which significantly accelerates their structural degradation.…”

“…Carbon materials are appealing lightweight, high-strength thermal structural materials used in aerospace equipment components due to their low density, outstanding hightemperature strength, low coefficient of thermal expansion (CTE), and superior heat shock resistance. [1][2][3][4][5][6][7] Nevertheless, the high oxygen sensitivity of carbon materials renders them vulnerable to catastrophic oxidation at high tem-# Deyu Qian, Yuexing Chen, and Xuanru Ren contributed equally to this work and should be considered co-first authors peratures and aerobic settings over 723 K, resulting in weight loss by gasification, 8,9 which significantly accelerates their structural degradation. The applied protective coating technique can form a diffusion barrier between the carbon material and oxygen, which has proven to be an effective method for improving the high-temperature stability of the carbon materials.…”

Oxidation Experiments and Kinetics Analysis of Nuclear Graphite ET-10 by Gas Analysis and Microstructure Observation

“…The mechanical and thermal properties of graphite are deteriorated by its oxidation [9][10][11][12]. Therefore, many studies have been carried out to investigate the oxidation behavior of different graphite [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The American Society for Testing and Materials (ASTM) issued the ASTM D7542 standard to measure oxidation performances of carbon and graphite materials in 2009 (updated in 2015) [28].…”