Interface Properties in a Porous‐Matrix Oxide Composite

Abstract

This study focuses on the interfacial properties of a family of porous matrix oxide composites with uncoated fibers. Measurements of debond energy and sliding stress are made using a modified version of the established fiber push-in test. Modifications include the following: (i) use of a sphero-conical indenter (not a sharp-tipped one) to produce only elastic deformation of the fibers, and (ii) analysis of the loop width (instead of absolute displacements) to ascertain interface properties. The method obviates the need for indentation tests on reference (non-sliding) fibers. It also mitigates the problems associated with the elastic deformation of the surrounding matrix. The measured debond toughnesses (about 0.05 J/m 2 ) are about two orders of magnitude lower than the fiber toughness. This ensures that debonding will occur when a matrix crack impinges on a fiber. Additionally, the sliding stresses are in the same range as those reported for C-coated Nicalon fibers in glass-ceramic matrices (about 5 MPa). The latter results are qualitatively consistent with the observed damage tolerance in these two seemingly disparate systems, as manifested in the degree of fiber pullout as well as the notch sensitivity of tensile strength.

Optically-transparent oxide fibre-reinforced glass matrix composites

“…11) showed that a greater stress is generated at the borosilicate glass/sapphire fibre interface than that at the interface of the same fibre with the soda-lime silicate glass, although in both cases the values obtained were comparable to values reported in the literature for a sapphire fibre-reinforced epoxy matrix composite [24], a Nextel™ 720 fibre-reinforced mullite matrix composite [25] and SiC reinforced LAS glass-ceramic [26] and borosilicate glass [22] matrix composites.…”

Degradation of a SiC‐SiC composite in water vapor environments

“…The interfacial sliding stress τ is computed by fitting the variation in loop width, with normalized force, ( F m being the force maximum in the respective cycle), via:where . This analysis is predicated on the assumption that the cyclic sliding distance is less than the slip distance at peak force; this condition is satisfied when .…”

Optimization of Alumina Slurry for Oxide-Oxide Ceramic Composites Manufactured by Injection Molding

“…In oxide/oxide composites, there are two ways to promote the debonding during crack propagation of the matrix: by the use of a fugitive interphase which induces small gap between the matrix and the fiber or by the use of a porous interphase. This latter leads to lowering the elastic properties and the fracture energy [3,4]. Also, the use of continuous fibers as the reinforcement helps to increase the inelastic deformation at the fiber-matrix interface, improving strength in the presence of holes and notches [5].…”