Significant improvements in the overall efficiency of thermal turbomachines can be achieved by reducing leakage flows in compressor and turbine modules. One approach to minimize leakage losses is the use of thermally sprayed coatings that function as so called abradable seals. In the hottest section of turbomachines, such seal coatings need to be manufactured from ceramics to be able to withstand the high temperature environment of modern engine designs. This paper reviews the design, manufacture and performance of ceramic abradable seals with varied chemistry, structure and properties of the seal coating. Emphasis is put on seal designs for operating temperatures up to 1200 °C (2190 °F) and cost effective solutions.
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