Toughening mechanisms in weak-matrix ceramic composites

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:7039390

Ha, Jowoong

The weak interfaces in composites are provided by reducing the chemical bonding and the residual thermal stresses between constituents. A new way to introduce the weak interface by induced porosity or damaged zones, so called porosity toughening or damage toughening, respectively, is proposed here to provide the rationale for guiding development of oxide/oxide composites. Porous oxide/oxide composites were fabricated using alumino-silicate fibers and magnesium alumino-silicate matrix and sintered at 1,100C and 1,200C. Both types of composites failed non-catastrophically in bending and tensile tests. The porous-matrix composites showed the low ultimate strength of 12.7 {plus minus} 3.4 MPa, but showed high work of fracture of 630 {plus minus} 206 J/m{sup 2} for the specimens fired at 1,100C when tested in tension. Damaged zones or porous phases were introduced into the interface region of model composites and effects determined using single-fiber pullout or single-rod pullout specimens. single-fiber pullout specimens with a damaged zone (by the oxidation of SiC fiber in situ) produced higher frictional stress than debonding strength. Frictional stresses increased up to 6.4 {plus minus} 3.4 MPa as pullout of the damaged fiber proceeded.

• Research Organization: Missouri Univ., Rolla, MO (United States)
• OSTI ID: 7039390
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
360603* -- Materials-- Properties
CERAMICS
CHALCOGENIDES
COMPOSITE MATERIALS
DAMAGE
FIBERS
FRACTURE PROPERTIES
INTERFACES
MATERIALS
MATRIX MATERIALS
MECHANICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
POROSITY
STRESS ANALYSIS
TEMPERATURE RANGE
TEMPERATURE RANGE 1000-4000 K