The oxidation behavior of SiC sintered with Al-B-C and improved oxidation resistance via heat treatments

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The oxidation behavior of high strength and high toughness SiC, sintered with Al, B, and C (ABC-SiC), was examined. Kinetic data were acquired and the parabolic rate constant for oxidation was determined and compared with literature data on various SiC materials. The role of secondary phases on the oxide morphology was explored. ABC-SiC was compared to commercially available SiC, Hexoloy, and SiC sintered with 10% yttrium aluminum garnet (YAG). Two-step sintering (pre-coarsening) was employed with holds for 48 hours at 600--1,600 C, prior to the typical hot-pressing conditions of 1,900 C for 1 hour, to change the chemistry and reduce ... continued below

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99 p.

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Sixta, M. December 1, 1997.

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  • Sixta, M. Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

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The oxidation behavior of high strength and high toughness SiC, sintered with Al, B, and C (ABC-SiC), was examined. Kinetic data were acquired and the parabolic rate constant for oxidation was determined and compared with literature data on various SiC materials. The role of secondary phases on the oxide morphology was explored. ABC-SiC was compared to commercially available SiC, Hexoloy, and SiC sintered with 10% yttrium aluminum garnet (YAG). Two-step sintering (pre-coarsening) was employed with holds for 48 hours at 600--1,600 C, prior to the typical hot-pressing conditions of 1,900 C for 1 hour, to change the chemistry and reduce the number of bubbles in the silica scale. The effects on the oxide thickness and integrity was examined as a function of the precoarsening heat treatment temperature. Additionally, the hot-pressed ABC-SiC was subjected to heat treatments (anneals) at 1,800 C for 1 hour in nitrogen, Ar, and vacuum environments, and the effects on subsequent oxidation were evaluated. The Ar and vacuum heat treatments dramatically improved the oxidation resistance of ABC-SiC. Finally, reoxidation experiments were performed to try to alter the surface chemistry of the SiC to improve the oxidation resistance. The four-point bend strengths and two-parameter Weibull plots of the most successful heat treatments were compared with the standard ABC-SiC to ensure that significant degradation did not result from altering the processing of the material.

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99 p.

Notes

OSTI as DE98057486

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  • Other Information: TH: Thesis (M.S.)

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  • Other: DE98057486
  • Report No.: LBNL--41464
  • Grant Number: AC03-76SF00098
  • Office of Scientific & Technical Information Report Number: 656715
  • Archival Resource Key: ark:/67531/metadc702362

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • December 1, 1997

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  • Sept. 12, 2015, 6:31 a.m.

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  • Nov. 5, 2015, 1:55 p.m.

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Sixta, M. The oxidation behavior of SiC sintered with Al-B-C and improved oxidation resistance via heat treatments, thesis or dissertation, December 1, 1997; United States. (digital.library.unt.edu/ark:/67531/metadc702362/: accessed December 15, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.