Oxidation Behavior of Mo-Si-B Alloys in Wet Air Metadata

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  • Main Title Oxidation Behavior of Mo-Si-B Alloys in Wet Air


  • Author: Kramer, M.
    Creator Type: Personal
  • Author: Thom, A.
    Creator Type: Personal
  • Author: Degirmen, O.
    Creator Type: Personal
  • Author: Behrani, V.
    Creator Type: Personal
  • Author: Akinc, M.
    Creator Type: Personal


  • Sponsor: United States. Department of Energy. Office of Environmental Management.
    Contributor Type: Organization
    Contributor Info: USDOE Office of Environmental Management (EM) (United States)


  • Name: Ames Laboratory
    Place of Publication: Iowa
    Additional Info: Ames Lab., IA (United States)


  • Creation: 2002-04-22


  • English


  • Content Description: Multiphase composite alloys based on the Mo-Si-B system are candidate materials for ultra-high temperature applications. In non load-bearing uses such as thermal barrier coatings or heat exchangers in fossil fuel burners, these materials may be ideally suited. The present work investigated the effect of water vapor on the oxidation behavior of Mo-Si-B phase assemblages. Three alloys were studied: Alloy 1 = Mo{sub 5}Si{sub 3}B{sub x} (T1)- MoSi{sub 2}- MoB, Alloy 2 = T1- Mo{sub 5}SiB{sub 2} (T2)- Mo{sub 3}Si, and Alloy 3 = Mo- T2- Mo{sub 3}Si. Tests were conducted at 1000 and 1100C in controlled atmospheres of dry air and wet air nominally containing 18, 55, and 150 Torr H{sub 2}O. The initial mass loss of each alloy was approximately independent of the test temperature and moisture content of the atmosphere. The magnitude of these initial losses varied according to the Mo content of the alloys. All alloys formed a continuous, external silica scale that protected against further mass change after volatilization of the initially formed MoO{sub 3}. All alloys experienced a small steady state mass change, but the calculated rates cannot be quantitatively compared due to statistical uncertainty in the individual mass measurements. Of particular interest is that Alloy 3, which contains a significant volume fraction of Mo metal, formed a protective scale. All alloys formed varying amounts of subscale Mo and MoO{sub 2}. This implies that oxygen transport through the external silica scale has been significantly reduced. For all alloys, water vapor accelerated the growth of a multiphase interlayer at the silica scale/unoxidized alloy interface. This interlayer is likely composed of fine Mo and MoO{sub 2} that is dispersed within a thin silica matrix. Alloy 3 was particularly sensitive to water accelerated growth of this interlayer. At 1100 C, the scale thickness after 300 hours increased from about 20 mm in dry air to nearly 100 mm in wet air.
  • Physical Description: 669 Kilobytes pages


  • Keyword: Alloys
  • Keyword: Controlled Atmospheres
  • Keyword: Air
  • Keyword: Oxidation
  • Keyword: Thermal Barriers
  • STI Subject Categories: 29 Energy Planning, Policy And Economy
  • Keyword: Evaporation
  • Keyword: Water Vapor
  • STI Subject Categories: 54 Environmental Sciences
  • Keyword: Fossil Fuels
  • Keyword: Heat Exchangers
  • Keyword: Silica


  • Other Information: PBD: 22 Apr 2002


  • Name: Office of Scientific & Technical Information Technical Reports
    Code: OSTI


  • Name: UNT Libraries Government Documents Department
    Code: UNTGD

Resource Type

  • Report


  • Text


  • Report No.: IS-5153
  • Grant Number: W-7405-Eng-82
  • DOI: 10.2172/797633
  • Office of Scientific & Technical Information Report Number: 797633
  • Archival Resource Key: ark:/67531/metadc742667


  • Display Note: OSTI as DE00797633