Oxide/Oxide Ceramic Matrix Composites in Gas Turbine Combustors

Abstract

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.

Processing and Properties of a Porous Oxide Matrix Composite Reinforced with Continuous Oxide Fibers

“…6 -8 By taking advantage of the CFCCs ability to operate at high temperatures with reduced need for cooling air, it is possible to increase the efficiency and also control the combustion process to minimize formation of species harmful to the environment, such as nitrogen oxides, carbon monoxide, and unburned hydrocarbons. 9 Most CFCCs that are commercially available are based on SiC fibers, with either oxide or non-oxide matrixes, and interphases consisting of carbon, BN, SiC or combinations thereof. The interphases are designed to provide a crack-deflecting layer between the matrix and fibers that prevents matrix cracks from extending through the fibers, thus allowing crack bridging to occur on matrix cracking enabling damage tolerance via notch insensitivity.…”

Unidirectional all-oxide mini-composites with crack-deflecting NdPO4 interface

“…[1][2][3][4][5][6] The physical and mechanical properties of new generation oxide/oxide CMCs enable innovative solutions for problems with materials in thermal protection systems and liners in gas-turbine engines, rocket engine, hot gas filter technologies, fire prevention, catalytic converters, soot filters and medical applications. [7][8][9] As a consequence, many gas-turbine manufactures are now placing greater emphasis on the evaluation of oxide/oxide components with enhanced high temperature stability and long service life in oxidising environments. [10][11][12][13][14][15][16][17][18][19][20] Although the reinforcement fibers and matrices are brittle, the obtained composites display quasi-ductile deformation behaviour due to operation of crack deflection, fiber-matrix debonding, crack bridging and fiber pull-out mech- * Corresponding author.…”

New liquid processing of oxide/oxide 3D wowen ceramic matrix composites

“…SiC/SiC ceramic matrix composites (CMC) have been proposed for applications at temperatures exceeding 1400°C, but questions on their service life have arisen since these materials are susceptible to oxidative embrittlement . This resulted in a growing scientific interest in oxide CMCs for high‐temperature applications ranging from gas turbine engines to thermal shields as these composites can be used in oxidizing environments and at temperatures up to 1100°C. This maximum temperature is currently limited by the commercially available fibrous reinforcements that are prone to embrittlement, but current fiber development aims at oxide fibers with higher service temperatures …”