Accession Number:

ADA156574

Title:

Characterization of Mechanical Damage Mechanisms in Ceramic Composite Materials.

Descriptive Note:

Interim technical rept. 24 May 84-23 May 85,

Corporate Author:

SOUTHWEST RESEARCH INST SAN ANTONIO TX

Personal Author(s):

Report Date:

1985-06-01

Pagination or Media Count:

68.0

Abstract:

This report summarizes research performed on two distinctly different ceramic composite materials. One was SiC-fiber reinforced LAS glass, while the other was an yttrium partially-stabilized, tetragonal-cubic phase zirconia. Silicon carbide fiber reinforced glass-ceramic matrix composite material has been tested in compression over a wide range in temperature. Both unidirectionally and multiaxially reinforced composites were tested. Compressive strength was measured, and pre-failure damage mechanisms characterized using acoustic emission and optical and scanning electron microscopy. Results are contrasted with corresponding tensile failure modes, and interpreted in terms of matrix microfracture, fiber kinking, and fiber orientation. Deformation and failure mechanisms are characterized for fully and partially yttria-stabilized single crystals tested in compression from 23 C to 1150 C. It is found that both types of material exhibit extensive plastic flow with increasing temperature. Tetragonal to monoclinic transformation-induced plasticity is not observed rather, plastic flow is related solely to dislocation activity. Evidence is found for apparent cubic to rhombohedral transformation during polishing, and reverse rhombohedral to cubic transformation during imposed compressive stress. Additional keywords Fracturemechanics Naval Research.

Subject Categories:

  • Laminates and Composite Materials

Distribution Statement:

APPROVED FOR PUBLIC RELEASE