Interface engineering in alumina fiber/glass composites

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7198117

Venkatesh, R

The goal of the present study is the development of tough alumina fiber/glass composites. Alumina and glass form a chemical bond and hence the resulting composite is brittle. SnO2 has been shown to have no solubility in alumina and very little diffusion in glass. A weakly bonded SnO2 interphase would aid in crack deflection, fiber debonding, and/or fiber pullout in alumina/SnO2/glass composites. The proposed study modifies the interface of alumina fiber/glass composites by incorporating a layer of SnO2, and characterizes the physical and mechanical properties of the resultant composites. Thermal stresses evaluated from a three-element cylindrical model showed radial tensile stress in both PRD-166/SnO2/glass and single crystal alumina Saphikon/SnO2/glass matrix composites. Even though there was weak mechanical bonding and tensile radial thermal stress at the PRD-166/SnO2 interface, the fibers could not be pushed out during a nanoindentation test. This was attributed to fiber roughness causing a compressive clamping stress at the PRD-166/SnO2 interface. PRD-166/glass matrix composites failed in a brittle manner whereas PRD-166/SnO2/glass matrix composites exhibited nonplanar failure with crack deflection and fiber bridging as the major toughening mechanisms. Saphikon/SnO2/glass matrix composites failed in a tough manner with extensive fiber pullout. This difference in the mode of failure was due to a relatively smooth Saphikon fiber. Fracture toughness of PRD-166/glass and PRD-166/SnO2/glass matrix composites measured with a chevron notch showed that the toughness of PRD-166/SnO2/glass matrix composite was higher than that of PRD-166/glass matrix composites because of crack deflection, fiber bridging, partial fiber debonding, and some fiber pullout. A judicious interplay of roughness induced radial stress and thermal stress distribution can be used to make a tough CMC.

• Research Organization: New Mexico Inst. of Mining and Technology, Socorro, NM (United States)
• OSTI ID: 7198117
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
360603* -- Materials-- Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BONDING
CHALCOGENIDES
CRACK PROPAGATION
FABRICATION
FRACTURE PROPERTIES
GLASS
INTERFACES
JOINING
MATERIALS
MATRIX MATERIALS
MECHANICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
STRESSES
THERMAL STRESSES
TIN COMPOUNDS
TIN OXIDES