Combustion liner having cooling holes with stepped lateral sidewalls

A method for creating a combustion liner, the method comprising:

• providing a base-alloy substrate having a bottom surface and a top surface;
• depositing a thermal barrier coat (TBC) metallic layer on the top surface of the base-alloy substrate;
• depositing a TBC ceramic layer on the TBC metallic layer, thereby forming a TBC interface therebetween, the TBC ceramic layer having a top surface exposed to combustion gases during operation within a gas turbine engine;
• and
• forming a plurality of cooling holes, each extending from an entrance aperture at the bottom surface of the base-alloy substrate and an oval-characteristic exit aperture at the top surface of the TBC ceramic layer, each of the plurality of cooling holes formed at an oblique angles to the top surface of the TBC ceramic layer, thereby forming the oval-characteristic exit aperture at the top surface of the TBC ceramic layer, the oval-characteristic exit aperture defining a long axis and a short axis, the long axis extending between an upstream side and a downstream side and the short axis extending between opposite lateral sides, thereby defining upstream and downstream sidewalls and opposite lateral sidewalls in each of the base-alloy substrate, the TBC metallic layer, and the TBC ceramic layer, wherein each of the cooling holes has a stepped sidewall profile recessing the TBC ceramic layer from TBC metallic layer at each of the upstream and downstream sidewalls and the opposite lateral sidewalls, wherein a first distance between the opposite lateral sidewalls of the TBC ceramic layer is greater than a second distance between the opposite lateral sidewalls of the TBC metallic layer.