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Gas turbine combustor concepts designed to give improved control of NOx emissions require the usage of hot uncooled walls. The main material properties needed in this application include mechanical and chemical stability at temperatures in excess of 1400°C for long times (>10 000 hours). Composites made from single crystal oxide fibre reinforced oxide with a compatible high temperature stable weak oxide interphase are potential candidate materials to meet these requirements. Alumina was chosen as a model material, unidirectional and 2D composites were processed and a suitable weak zirconia interphase was designed. The process was scaled-up to make production of larger panels and components possible. Mechanical testing was carried out at room temperature to characterise the performance of the material in the as produced and thermally aged condition. Room temperature mechanical properties compared well with other current ceramic composites and excellent high temperature stability was demonstrated. The applicability of the composite as a material for uncooled combustor walls is to be further assessed by evaluation in a combustor test rig. Results from computational fluid dynamics and finite element calculations as well as results from combustor rig tests of monolithic and composite ceramic tiles will be presented.

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SUMMARY Ceramic‐matrix composites have been produced using unidirectionally aligned Textron SCS‐6 fibres in a sintered reaction‐bonded matrix. A tape‐casting technique was used to produce a prepreg sheet that could be cut and stacked to form a layup. Al2O3 and Y2O3 were used as sintering aids, final sintering being carried out in a hot press at 1700°C. Matrix, fibre and interfacial microstructure has been characterized using analytical microscopical techniques. X‐ray mapping of the carbon and silicon distribution at the fibre–matrix interface was carried out, and evidence of reaction between the outer carbon‐rich layer of the fibre and the matrix was found. Micromechanical behaviour of interfaces has been investigated and compared with interfacial microstructure and macromechanical properties.