Method for improving the cooling effectiveness of a gaseous coolant stream, and related articles of manufacture

A method for improving the cooling effectiveness of a fluid which flows through at least one row of passage holes in a substrate, out to a high-temperature surface of the substrate, comprising the following steps:

• (I) covering each hole with a curable plug material;
• (II) curing the plug material;
• (III) applying a mask over the row of holes, wherein the mask has dimensions substantially identical to pre-selected dimensions for a slot;
• (IV) applying a thermal barrier coating (TBC) system over the substrate and the mask, said TBC system comprising a bond layer and a thermal barrier coating;
• (V) removing the mask to uncover the slot;
• and
• (VI) removing the plug material;
• wherein the passage holes have an average throat diameter, and the dimensions of the mask are selected to provide the slot with a depth that is less than the average throat diameter of the passage holes.

An article in the form of a substrate, comprising:

• (I) a first surface exposed to a first fluid;
• (II) a second surface exposed to a hotter second fluid, spaced from said first surface;
• (III) at least one row or other pattern of passage holes extending through the substrate from the first surface to a slot on the second surface;
• said holes having an average throat diameter d, and said slot having a depth D;
• wherein the depth D is less than the diameter d;
• and
• (IV) at least one coating, covering the portion of the second surface exclusive of the slot;
• wherein the slot has a bottom surface substantially parallel to the second surface, and wherein the bottom surface of the slot is in fluid communication with the passage holes.

A superalloy substrate within a turbine engine, comprising:

• (I) a first surface exposed to a coolant fluid;
• (II) a second surface intermittently exposed to a hot combustion gas, spaced from said first surface;
• (III) at least one row of film cooling holes through which the coolant fluid flows, extending through the substrate from the first surface to a slot on the second surface;
• said holes having an average throat diameter d;
• and
• (IV) a zirconia-based thermal barrier coating system over the portion of the second surface exclusive of the slot;
• wherein the slot has a bottom surface substantially parallel to the second surface, said bottom surface of the slot being in fluid communication with the film cooling holes, and wherein the depth of the slot is less than the average throat diameter of the film cooling holes.