Modes of oxidation in SiC-reinforced mullite/ZrO{sub 2} composites: Oxidation vs depth behavior

Journal Article · Fri Apr 23 04:00:00 EDT 1999 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(99)00027-0· OSTI ID:353484

Lin, C C ^[1]; Zangvil, A ^[2]; Ruh, R ^[3]

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1. National Chia Tung Univ., Hsinchu (Taiwan, Province of China). Dept. of Materials Science and Engineering
2. Univ. of Illinois, Urbana, IL (United States)
3. Air Force Wright Aeronautical Lab., Wright-Patterson AFB, OH (United States)

Two basic oxidation modes of composites with oxidizing particles in a non-oxidizing matrix have been observed. Mode I is defined as the complete oxidation of all the particles within an outer layer of the composite, while mode II exhibits partial oxidation of the particles, deep into the composite. Using microscopic observations to plot the silica layer thickness on particles (whiskers) vs the depth of the particles (whiskers) below the composite surface is proposed as a powerful means of categorizing and quantifying actual oxidation modes. Thus, mullite/SiC-whisker composites were found to have mode I oxidation behavior, while certain (mullite + ZrO{sub 2})/SiC-whisker composites were found to exhibit mode II behavior, followed by a mixed mode after severe exposures. It is proposed that mode II behavior appears when oxygen diffusivity in the matrix is much higher than that in the product oxide layer.

• Sponsoring Organization: National Science Council, Taipei (Taiwan, Province of China); USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-91ER45439
• OSTI ID: 353484
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 6 Vol. 47; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPOSITE MATERIALS
DEPTH
DIFFUSION
MULLITE
OXIDATION
PARTICLES
SILICON CARBIDES
SURFACES
ZIRCONIUM OXIDES