Showing papers on "Ceramic matrix composite published in 1977"

Bonding mechanism evidence in a ceramic–nonprecious alloy system

Abstract: Bonding between porcelain and dental ceramic alloys is thought to be dependent upon the establishment of a continous electron structure across the ceramicmetal interface (Pask, Proc. Procelain Enamel Inst., 33, 1, 1971). Such a structure most likely results from the compatibility of metal ions at the metal surface saturated in an oxide form with the complex oxide structure of the ceramic matrix. Reaction zone compounds are expected to play a prominent role in the strength of the ceramic–metal bonds but thus far none have been detected or identified. The present study was centered on the determination of possible adherence zone compounds in four composite ceramic–metal couples examined by x-ray energy analysis. Elemental analysis of four couples revealed the presence of a predominant AlCr interaction resulting from the formation of an AlCrO compound or mixed oxide complex. The Cr ions were supplied by the Cr2O3 oxide layer at the metal surface and the Al was provided by the initial bonding-agent coating.

Crack growth in hybrid fibrous composites

Abstract: A preliminary analysis is made of the energetics of transverse crack growth in a brittle elastic matrix bridged by elastic fibres fictionally bonded to the matrix. Studies made of the stability of a crack of finite length in a brittle polymeric material reinforced with steel wires are found to be in reasonable agreement with the predictions of the theory. It is proposed that the stability of transverse cracks in a very brittle matrix could be increased substantially by the inclusion of a second fibre component designed specifically to increase the work of fracture of the matrix. This has been shown to be possible using a very small volume fraction of glass fibres as a matrix toughening component and it has also been observed that stable transverse matrix crack growth can be achieved with composite systems of this type. This principle might have applications in the design of hybrid composites utilizing either a brittle polymeric or ceramic matrix.

Research on graphite reinforced glass matrix composites

Abstract: High levels of mechanical performance in tension, flexure, fatigue, and creep loading situations of graphite fiber reinforced glass matrix composites are discussed. At test temperatures of up to 813 K it was found that the major limiting factor was the oxidative instability of the reinforcing graphite fibers. Particular points to note include the following: (1) a wide variety of graphite fibers were found to be comparable with the glass matrix composite fabrication process; (2) choice of fiber, to a large extent, controlled resultant composite performance; (3) composite fatigue performance was found to be excellent at both 300 K and 703 K; (4) composite creep and stress rupture at temperatures of up to 813 K was limited by the oxidative stability of the fiber; (5) exceptionally low values of composite thermal expansion coefficient were attributable to the dimensional stability of both matrix and fiber; and (6) component fabricability was demonstrated through the hot pressing of hot sections and brazing using glass and metal joining phases.

Reinforced ceramic structure

Abstract: A reinforced ceramic structure is provided utilizing a composite reinforcing member embedded in a ceramic casting. The reinforcing member is optimally unidirectional composite rope, preferably of graphite epoxy or silicon carbide. By virtue of the thermal expansion rate of the reinforcing member being substantially the same as the ceramic material, the reinforcement member remains integral with the ceramic casting material though subjected to thermal cycles and provides an increase in the tensile strength of ceramic casting heretofore unobtained.