Weak interphase Ox/Ox CMCs

About the Project

Traditional Ox/Ox Ceramic Matrix Composites (CMCs) do not apply a fibre coating, instead they rely on a high porosity ‘weak matrix’ to deflect cracks and improve toughness. However, this strategy can result in poor matrix-dominated properties, such as through-thickness thermal conductivity and interlaminar shear strength. ‘Weak interphase’ Ox/Ox CMCs are of potential interest to retain the desirable features of oxide systems (e.g. good environmental resistance), whilst enabling a higher density matrix to improve the interlaminar properties.

This project aims to develop and demonstrate the room temperature mechanical performance of a weak interphase Ox/Ox CMC system. Novel manufacturing strategies to produce a high density oxide matrix will be investigated. Subsequently, initial composite manufacturing trials and fibre push in / push out tests will be performed to understand the factors affecting the interfacial shear strength / debonding energy, such as coating thickness and ageing temperature. Finally, an interphase coating and matrix infiltration procedure will be down-selected to manufacture and test the mechanical properties of a flat laminate. If successful, the developed system may be taken forwards as a candidate to replace existing / developmental Ox / Ox CMC components, e.g. heat shields.