Oxidation Behavior of Nuclear Graphite(IG110) with Surface Roughness

2006 ◽  
Vol 43 (10) ◽  
pp. 613-618 ◽  
Keyword(s):  
Surface Roughness ◽  
Oxidation Behavior ◽  
Nuclear Graphite

scholarly journals Oxidation Behavior of Matrix Graphite and Its Effect on Compressive Strength

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Xiangwen Zhou ◽  
Cristian I. Contescu ◽  
Xi Zhao ◽  
Zhenming Lu ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Pore Formation ◽  
Oxidation Behavior ◽  
Mercury Porosimetry ◽  
Strength Loss ◽  
Nuclear Graphite ◽  
Matrix Graphite ◽  
Oxidation Performance ◽  
Lower Oxidation ◽  
High Temperature Gas

Matrix graphite (MG) with incompletely graphitized binder used in high-temperature gas-cooled reactors (HTGRs) is commonly suspected to exhibit lower oxidation resistance in air. In order to reveal the oxidation performance, the oxidation behavior of newly developed A3-3 MG at the temperature range from 500 to 950°C in air was studied and the effect of oxidation on the compressive strength of oxidized MG specimens was characterized. Results show that temperature has a significant influence on the oxidation behavior of MG. The transition temperature between Regimes I and II is ~700°C and the activation energy (Ea) in Regime I is around 185 kJ/mol, a little lower than that of nuclear graphite, which indicates MG is more vulnerable to oxidation. Oxidation at 550°C causes more damage to compressive strength of MG than oxidation at 900°C. Comparing with the strength of pristine MG specimens, the rate of compressive strength loss is 77.3% after oxidation at 550°C and only 12.5% for oxidation at 900°C. Microstructure images of SEM and porosity measurement by Mercury Porosimetry indicate that the significant compressive strength loss of MG oxidized at 550°C may be attributed to both the uniform pore formation throughout the bulk and the preferential oxidation of the binder.

Oxidation Behaviors of Inconel 740H in Air and Dynamic Steam

2016 ◽  
Vol 35 (7) ◽  
pp. 697-704
Author(s):  
Jintao Lu ◽  
Zhen Yang ◽  
Songqian Xu ◽  
Haiping Zhao ◽  
Y. Gu
Keyword(s):  
Surface Roughness ◽  
Oxidation Product ◽  
Oxidation Rate ◽  
Power Plants ◽  
Oxidation Behavior ◽  
Test Environment ◽  
Parabolic Law ◽  
Oxide Particles ◽  
Pure Steam ◽  
Oxidation Behaviors

AbstractInconel 740H alloy is a candidate material for 700°C advanced ultra-supercritical (A-USC) coal-fired power plants application as superheater/reheater tube. In this work, oxidation behavior of Inconel 740H alloy was studied in static air at 750°C and 850°C, and in dynamic pure steam at 750°C, respectively. The alloy was oxidized approximately following a parabolic law in three test environment. In the static air, the oxidation rate at 850°C was about 50 times of that at the 750°C. More NiCrMn spinal and TiO2 were detected after oxidation at 850°C. Cr2O3, however, was the main oxidation product at 750°C. In the pure steam, Cr2O3 was still the main oxidation product. The oxidation rate was about 2.6 times of that in static air, but the surface roughness was much smaller and edges of oxide particles were more blurred. There was no evidence of cracks or spallation in three test environments.

scholarly journals Effect of Surface Roughness on Early Stage Oxidation Behavior of Ni-Base Superalloy IN 625

2018 ◽  
Vol 1 (3) ◽  
pp. 32 ◽  
Author(s):  
Wojciech Nowak
Keyword(s):  
Surface Roughness ◽  
Oxidation Behavior ◽  
Early Stage ◽  
Surface Preparation ◽  
Horizontal Tube ◽  
Optical Emission ◽  
Emission Spectrometry ◽  
Ground Sample ◽  
Base Superalloy ◽  
Effect Of Surface

In the present work the effect of surface roughness on oxidation behavior during the early stages of high temperature exposure of Ni-base superalloy IN 625 is described. The surface roughness was described using standard contact profilometer as well as novel method, fractal analysis. It was found that the different surface preparation resulted in a difference in roughness with a parameter increase of at least one order of magnitude for the ground sample as compared with the polished sample. The oxidation test was performed in a horizontal tube furnace. Post-exposure analyses including glow discharge optical emission spectrometry (GD-OES) and scanning electron microscopy (SEM), which revealed that grinding lowers the oxidation kinetics of IN 625 from 1.76 × 10−12 cm2·s−1, obtained for polished sample, to 9.04 × 10−13 cm2·s−1. It was found that surface preparation influences the oxide scale composition and morphology. The hypothesis explaining the mechanism responsible for the changes in oxidation behavior is proposed as well.

scholarly journals Effect of Surface Roughness on the Oxidation Behavior of a Directionally Solidified Ni-Based Superalloy at 1,100 °C

2015 ◽  
Vol 28 (3) ◽  
pp. 381-385 ◽  
Author(s):  
Li Wang ◽  
Wei-Guo Jiang ◽  
Xiang-Wei Li ◽  
Jia-Sheng Dong ◽  
Wei Zheng ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Oxidation Behavior ◽  
Directionally Solidified ◽  
Effect Of Surface

scholarly journals Oxygen adsorption and CO desorption behavior of B- and N-doped vacancy defected nuclear graphite by DFT study

RSC Advances ◽  
2017 ◽  
Vol 7 (6) ◽  
pp. 3257-3264 ◽  
Author(s):  
Juan Liu ◽  
Tongxiang Liang ◽  
Chen Wang ◽  
Wenzheng Lai
Keyword(s):  
Oxidation Behavior ◽  
Oxygen Adsorption ◽  
Dft Study ◽  
Adsorption And Desorption ◽  
Graphite Oxidation ◽  
Nuclear Graphite ◽  
Two Factors ◽  
Gasification Products

Oxygen adsorption and desorption of gasification products are two factors that influence graphite oxidation behavior.

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