Author: Gregory PowhidaPublisher:
ISBN:
Category :
Languages : en
Pages : 56
Book Description
Accelerated Oxidation of Silicon Carbide by Water Vapor at 1250°C
Author: Gregory PowhidaOxidation of Silicon Carbide in Oxygen with Water Vapor
Author: Samuel W. MouckOxidation of Silicon Carbide in the Presence of Alkali Salt Vapors
Author: Vinod Kumar PareekOxidation of Silicon Carbide in an Alkali Vapor Environment
Author: Vinod Kumar PareekPublisher:
ISBN:
Category : Oxidation
Languages : en
Pages : 70
Book Description
Silicon Carbide Oxidation in High Temperature Steam
Author: Ramsey Paul ArnoldPublisher:
ISBN:
Category :
Languages : en
Pages : 126
Book Description
The commercial nuclear power industry is continually looking for ways to improve reactor productivity and efficiency and to increase reactor safety. A concern that is closely regulated by the Nuclear Regulatory Commission is the exothermic zircaloy-steam oxidation reaction which can potentially occur during a loss of coolant accident (LOCA), and may become autocatalytic beyond 1,200 0C, thus generating a large amount of hydrogen. The concern for the zircaloy oxidation reaction has been heightened since the March 2011 events of Fukushima, Japan. One solution offering promising results is the use of silicon carbide (SiC) cladding in nuclear reactor fuel rod designs. SiC, a robust ceramic which reacts very slowly with water or steam, has many features that meet or exceed that of zircaloy including the ability to withstand higher temperatures due to a higher melting point and the ability to absorb fewer neutrons than zircaloy which would allow for increased safety margins and fuel burnup. An experimental investigation of the oxidation performance of a-SiC during a postulated LOCA event was performed. The test facility was designed and fabricated to test the oxidation rates of zircaloy and SiC in a high temperature, high-purity, flowing steam environment. Studies of zircaloy-4 oxidation were conducted to validate the test facility for this purpose. Thirty six zircaloy-4 tests lasting up to 30 minutes, at temperatures ranging from 800°C to 1,200°C, were completed and compared to existing models and literature data. Additionally, six longer duration a-SiC tests lasting from 8 hours to 48 hours, at temperatures of 1,140°C and 1,200°C, were completed. These tests clearly show that, from an oxidation perspective, SiC significantly outperforms zircaloy in high-flowing, superheated steam. For zircaloy, results from the most intense temperature/duration testing combination of 1,200°C for 30 minutes show 15.6 percent weight gain. For the most intense SiC tests at 1,200°C for eight hours, a weight loss of two orders of magnitude less occurred, a 0.077 percent weight loss. The four 24 hour and 48 hour SiC tests at 1,140°C also correlate well with the expected paralinear oxidation trend and further confirm that SiC is more resistant to oxidation in high temperature steam than zircaloy.
Kinetics of Silicon Thermal Oxidation in Water Vapor and in Water Vapor-oxygen Mixtures
Author: Takashi NakayamaPublisher:
ISBN:
Category : Silicon
Languages : en
Pages : 99
Book Description
Effect of Water Vapor on the Oxidation and Thermo-mechanical Behavior of SiC and Si3N4 Ceramics
Author: Hongsang RhoPublisher:
ISBN:
Category : Ceramic materials
Languages : en
Pages : 364
Book Description
Oxidation of Ultra High Temperature Ceramics in Water Vapor
Author: Nasa Technical Reports Server (Ntrs)Publisher: BiblioGov
ISBN: 9781289263522
Category :
Languages : en
Pages : 24
Book Description
Ultra High Temperature Ceramics (UHTCs) including HfB2 + 20v/0 SiC (HS), ZrB2 + 20v/0 SiC (ZS), and ZrB2 + 30v/0 C + 14v/0 SiC (ZCS) have been investigated for use as potential aeropropulsion engine materials. These materials were oxidized in water vapor (90 percent) using a cyclic vertical furnace at 1 atm. The total exposure time was 10 h at temperatures of 1200, 1300, and 1400 C. CVD SiC was also evaluated as a baseline for comparison. Weight change, X-ray diffraction analyses, surface and cross-sectional SEM and EDS were performed. These results are compared with tests ran in a stagnant air furnace at temperatures of 1327 C for 100 min, and with high pressure burner rig (HPBR) results at 1100 and 1300 C at 6 atm for 50 h. Low velocity water vapor does not make a significant contribution to the oxidation rates of UHTCs when compared to stagnant air. The parabolic rate constants at 1300 C, range from 0.29 to 16.0 mg(sup 2)cm(sup 4)/h for HS and ZCS, respectively, with ZS results between these two values. Comparison of results for UHTCs tested in the furnace in 90 percent water vapor with HPBR results was difficult due to significant sample loss caused by spallation in the increased velocity of the HPBR. Total recession measurements are also reported for the two test environments.
Oxidation of Ultra High Temperature Ceramics in Water Vapor
Author: National Aeronautics and Space Administration (NASA)Publisher: Createspace Independent Publishing Platform
ISBN: 9781721650033
Category :
Languages : en
Pages : 34
Book Description
Ultra High Temperature Ceramics (UHTCs) including HfB2 + 20v/0 SiC (HS), ZrB2 + 20v/0 SiC (ZS), and ZrB2 + 30v/0 C + 14v/0 SiC (ZCS) have been investigated for use as potential aeropropulsion engine materials. These materials were oxidized in water vapor (90 percent) using a cyclic vertical furnace at 1 atm. The total exposure time was 10 h at temperatures of 1200, 1300, and 1400 C. CVD SiC was also evaluated as a baseline for comparison. Weight change, X-ray diffraction analyses, surface and cross-sectional SEM and EDS were performed. These results are compared with tests ran in a stagnant air furnace at temperatures of 1327 C for 100 min, and with high pressure burner rig (HPBR) results at 1100 and 1300 C at 6 atm for 50 h. Low velocity water vapor does not make a significant contribution to the oxidation rates of UHTCs when compared to stagnant air. The parabolic rate constants at 1300 C, range from 0.29 to 16.0 mg(sup 2)cm(sup 4)/h for HS and ZCS, respectively, with ZS results between these two values. Comparison of results for UHTCs tested in the furnace in 90 percent water vapor with HPBR results was difficult due to significant sample loss caused by spallation in the increased velocity of the HPBR. Total recession measurements are also reported for the two test environments. Nguyen, QuynhGiao N. and Opila, Elizabeth J. and Robinson, Raymond C. Glenn Research Center NASA/TM-2004-212923, E-14363
Silicon Carbide, a High Temperature Semiconductor
Author: Joseph R. O'ConnorPublisher: Pergamon
ISBN:
Category : Science
Languages : en
Pages : 552
Book Description