Forming cooling passages in thermal barrier coated, combustion turbine superalloy components

A method for forming a cooling passage in an investment cast, superalloy blade or vane component for a combustion turbine engine, the component having a component wall delimited by first and second wall surfaces, the cooling passage extending through the component wall between the first and second wall surfaces, comprising:

• forming a partially completed cooling passage in the first wall surface, the partially completed cooling passage having an entrance formed in the first wall surface, corresponding to a cooling passage inlet or outlet, and a skewed passage path within the first wall surface, having a terminus distal and laterally offset from the entrance, and an overhanging shield layer of superalloy material in the first wall that is interposed between the laterally offset passage terminus and the surface proximate the entrance;
• applying a thermal barrier coating over the first wall surface and the entrance;
• providing an ablation device for ablating thermal barrier coating and superalloy material;
• aligning the ablation device proximate the entrance;
• ablating thermal barrier coating material from the partially completed cooling passage with the ablation device, reaching the passage terminus;
• and
• completing the cooling passage by ablating superalloy material out of the skewed path, along the partially completed cooling passage path from the terminus to the other of the cooling passage inlet or outlet in a the second wall surface, the overhanging shield layer of superalloy material inhibiting damage to thermal barrier coating material proximate the entrance caused by ejection of ablated superalloy material out of the entrance.