COMPOSITE HAVING VELOCITY BARRIER LAYER

摘要

PROBLEM TO BE SOLVED: To reduce the retreat velocity of an environmental barrier coating (EBC) when a composite is used or utilized in turbine vane and blade positions to be exposed to high-velocity, high-temperature, and aqueous environments. SOLUTION: The composite comprises a silicon based substrate, the EBC with a top layer, wherein the top layer comprises a velocity barrier layer. The velocity barrier layer is any layer positioned between a flowing gas stream and the underlying EBC protective layer which acts to reduce the velocity of the gas stream which otherwise would impinge on the underlying protective layer. The velocity barrier layer preferably (1) reduces the velocity of an impinging gas stream by at least 50% across the thickness of the velocity barrier layer and (2) also preferably reduces the velocity of the impinging gas stream to less than 1 meter per second across the thickness of the velocity barrier layer. COPYRIGHT: (C)2005,JPO&NCIPI