Creep of Hi-Nicalon S Ceramic Fiber Tows at 800 deg C in Air and in Silicic Acid-Saturated Steam

Abstract

C. A facility was demonstrated that successfully resolved problems highlighted by previous attempts to study SiC fibers in steam. Monotonic tension and creep tests were conducted to characterize the fibers. The tensile strength of the fibers showed little dependence on applied stress rate, indicating a resistance to environmentally assisted crack growth. Climb-controlled diffusion in air and grain boundary sliding in silicic acid-saturated steam were the dominant damage mechanisms. Silicic acid-saturated steam had a degrading effect on the mechanical performance of the fibers, but much less than unsaturated steam environments. The Monkman-Grant relationship was demonstrated for Hi-NicalonTM S fibers and may be used to predict creep lifetime of fibers, fiber tows, and CMCs. Microstructural analysis showed a dependence of oxide thickness on applied stress.

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Document Details

Document Type
Technical Report
Publication Date
Dec 26, 2015
Accession Number
AD1003576

Entities

People

  • Scott J Robertson

Organizations

  • Air Force Institute of Technology

Tags

Communities of Interest

  • Advanced Electronics
  • Air Platforms
  • Biomedical
  • Energy and Power Technologies
  • Ground and Sea Platforms

DTIC Thesaurus Topics

  • Ceramic Materials
  • Ceramic Matrix Composites
  • Chemical Reactions
  • Chemistry
  • Creep
  • Crystal Structure
  • Failure Mode And Effect Analysis
  • Heat Energy
  • Material Degradation Processes
  • Materials
  • Materials Engineering
  • Materials Laboratories
  • Materials Processing
  • Materials Science
  • Materials Testing
  • Mechanical Working
  • Mechanics

Readers

  • Materials Science (Mechanical Engineering).
  • Materials Science and Engineering.
  • Reinforced Composite Materials