Abstract

The turbine blade tip clearance control system presently used with existing turbine blade uses an abradable seal material with a conventional squealer tip. Others use a thin, coating added to the tip of the blade. The present turbine blade tip control system minimizes the problem of controlling the clearance between the blade and the shroud and overcomes the problem of wearing away of the thin coating added to the tip by using a rub tolerant, high-temperature seal material coating on a turbine shroud and a turbine blade made of at least two materials. The combination of the coating and an outer tip being of a different material than the metallic body also minimizes the problems associated with the burning of dirty fuels. The blade has a metallic body of high strength and the outer tip has a strength less than the strength of the body and made of a material resistant to oxidation, sulfidation and thermal fatigue at operating temperatures. The outer tip has a radial length "L" at least 1 mm in length.