US Patent 7645123 Turbine blade with TBC removed from blade tip region

A turbine blade having a squealer tip rail forming a squealer pocket on the blade tip, and a row of blade tip peripheral film cooling holes on the pressure side and suction side of the blade for cooling the blade tip rails. A TBC is applied to the pressure side and suction side walls of the blade up to the row of tip peripheral film cooling holes, leaving these surfaces uncovered. The squealer pocket is covered with TBC while the top surfaces of the tip rails are uncovered. The surface of the airfoil wall above the row of tip peripheral cooling holes is without a TBC so that the metal surface will be exposed to the layer of film cooling holes discharged from the tip peripheral cooling holes.