Patent ID: 7479328

Claim:
A shroud segment for a turbomachine, the turbomachine having a flow duct, and a bladed rotor wheel arranged in the flow duct, which flow duct and bladed rotor wheel perform a relative rotary movement and which are flown by a hot working gas, the shroud segment comprising: a metallic substrate having an outer surface exposed to a cooling gas flow external of the flow duct of the turbomachine; and a ceramic rubbing coating having an inner surface and an outer surface, the ceramic rubbing coating outer surface bonded directly to at least one of an inner surface of the metallic substrate and a metallic bond layer attached directly to the metallic substrate, the ceramic rubbing coating inner surface being abradable by blade tips of the bladed rotor wheel for the formation of a narrow sealing gap, wherein the rubbing coating comprises a high-temperature resistant, thermally conductive ceramic material which is cooled through the metallic substrate by the exposure of the outer surface of the metallic substrate to the cooling gas flow, wherein the ceramic material is a spinel and the coefficient of thermal conductivity of the rubbing coating is ≧2.0 W/mK at an operating temperature; the thickness of the rubbing coating being more than 0.4 mm.