Development of Ceramic Components for Gas Turbine Application

The use of advanced ceramics for the critical components in the hottest sections of gas turbines offers the most promising solution for increasing their efficiency. As part of a project sponsored by the Dutch Organisation for Energy and the Environment, materials suitable for use in a small gas turbine were developed. The preparation and characterisation of in- situ reinforced Si3N4 (SSN) and long fibre-reinforced SiC (SiCf/SiC), and several metal-ceramic joining techniques, are discussed. SSN is shown to be the most developed material and has the best properties. It is well-suited for highly demanding applications, such as guide vanes. The shear strength of SSN/In-600 alloy joints is 50.3 MPa at RT. SiCf/SiC shows low mechanical properties (three-point bending strength of 173 MPa) because the material is not fully densified. The fracture energy (1100 J/m2) is high compared with that for SSN (280 J/m2), indicating the toughening effect of the long fibres, and SiCf/SiC appears to be promising as a heat shield material.