The disclosure relates generally to rotating machinery or turbomachinery, such as gas and/or steam turbines, compressors, and/or machines including such turbines and/or compressors. More particularly, the disclosure relates to the removal of material deposited over and/or in cooling holes of a part, such as a combustor jacket.
During manufacture, repair, and/or rehabilitation of gas turbines, coatings are applied to some parts. For example, in turbomachinery, particularly in gas turbines, a thermal barrier coating (TBC) can be applied to protect underlying material of the parts to which the TBC is applied from heat. A TBC can include a ceramic layer, which can include a variety of ceramic materials, the most commonly used of which is currently yttria-stabilized zirconia (YSZ). In addition, a typical TBC can include a metallic bonding layer applied to the underlying material of the part, and a thermally grown oxide layer on the metallic bonding layer, to which the ceramic layer is applied.
When such a coated turbomachine part includes cooling holes, the cooling holes can become partially or completely occluded, and the coating(s) can also form deposits on interior portions of passages leading to the cooling holes. Typically, portions of the part on which the coating is not desired are covered with a masking agent, the coating is applied to the part, and overspray is removed by mechanical grinding. The masking agent can then be removed, such as by abrasion and/or burning or other chemical means.