Oxygen Diffusion and Reaction Kinetics in Continuous Fiber Ceramic Matrix Composites

Abstract

Previous stressed oxidation tests of C/SiC composites at elevated temperatures (350 deg C to 1500 deg C) and sustained stresses (69 MPa and 172 MPa) have led to the development of a finite difference cracked matrix model. The times to failure in the samples suggest oxidation occurred in two kinetic regimes defined by the rate controlling mechanisms (i.e.; diffusion controlled and reaction controlled kinetics). Microstructural analysis revealed preferential oxidation along as-fabricated, matrix microcracks and also suggested two regimes of oxidation kinetics dependent on the oxidation temperature. Based on experimental results, observation, and theory, a finite difference model was developed. The model simulates the diffusion of oxygen into a matrix crack bridged by carbon fibers. The model facilitates the study of the relative importance of temperature, the reaction rate constant, and the diffusion coefficient on the overall oxidation kinetics.

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Document Details

Document Type
Technical Report
Publication Date
Feb 01, 1999
Accession Number
ADA373588

Entities

People

  • Andrew J. Eckel
  • James D. Cawley
  • Michael C. Halbig

Organizations

  • National Aeronautics and Space Administration

Tags

Communities of Interest

  • C4I
  • Energy and Power Technologies
  • Space

DTIC Thesaurus Topics

  • Carbon Fibers
  • Ceramic Matrix Composites
  • Chemical Kinetics
  • Composite Materials
  • Databases
  • Dielectric Gases
  • Diffusion Coefficient
  • Equations
  • High Temperature
  • Kinetics
  • Material Degradation Processes
  • Materials
  • Materials Laboratories
  • Military Research
  • Silicon Carbide
  • Technical Ceramics
  • Two Dimensional

Fields of Study

  • Materials science

Readers

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