Strengthening and toughening mechanisms in ceramic fiber-reinforced glass matrix composites

Thesis/Dissertation · Sat Dec 31 23:00:00 EST 1988

OSTI ID:6314009

Zern, C A

A composite system containing FP-alumina fibers and a borosilicate glass matrix was studied. CVD carbon coatings were applied to the fibers to control the degree of bonding at the interface. Processing techniques of slurry infiltration and hot pressing were used to fabricate composites with fiber fractions ranging from 20 to 50 percent. The most significant result is the determination of the role of the fiber/matrix interface in dictating the mechanical properties. The carbon coatings enhanced the mechanical properties of the composites by reducing the shear strength of the fiber matrix interface. The interfacial shear stress for fiber movement was measured using an indentation method. Composites with uncoated fibers did not show fiber sliding due to the strong bonding. Fibers in the composites with 22 and 47 percent C-coated fibers slid in their matrix cavities during measurement and exhibited shear strength for fiber movement values of 100 and 43 MPa respectively. These values are greater than interfacial shear strength values from the literature for debonded fiber composites. Interfacial shear stress required for fiber movement after debonding the fiber from the matrix was measured on thin samples. Values of 37 and 10 MPa were found for the 22 and 47 percent fiber samples respectively. Contributions to the interfacial shear stress for fiber movement include: friction between two surfaces, surface roughness of the fibers, radial interfacial pressure due to thermal expansion differences, a chemical bonding effect, and a residual shear stress for fiber movement include: friction between two surfaces, surface roughness of the fibers, radial interfacial pressure due to thermal expansion differences, a chemical bonding effect, and a residual shear stress for fiber movement.

• Research Organization: Rutgers--the State Univ., New Brunswick, NJ (USA)
• OSTI ID: 6314009
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BOROSILICATE GLASS
CHALCOGENIDES
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
COMMINUTION
COMPOSITE MATERIALS
DEPOSITION
DISPERSIONS
EXPANSION
FABRICATION
FAILURE MODE ANALYSIS
FIBERS
FRACTURING
FRICTION
GLASS
HOT PRESSING
MATERIALS
MATERIALS WORKING
MATRIX MATERIALS
MECHANICAL PROPERTIES
MIXTURES
OXIDES
OXYGEN COMPOUNDS
PRESSING
SLURRIES
SURFACE COATING
SURFACE PROPERTIES
SUSPENSIONS
SYSTEM FAILURE ANALYSIS
SYSTEMS ANALYSIS
THERMAL EXPANSION