United Technologies Corporation

Peter Wrabel

Peter J Draghi

Brian J Shurman

Dale A Simard

Shawn J Gregg

Timothy P Murphy

An airfoil comprises a substrate, a residual abrasive coating and a supplemental abrasive coating. The substrate extends along a tip section of the airfoil, from a leading edge to a trailing edge. The residual abrasive coating comprises a two-phase abrasive and metal matrix material bonded to the substrate, on the tip section of the airfoil. The supplemental abrasive coating comprises a two-phase abrasive and metal matrix material bonded to the residual abrasive coating and to the substrate adjacent the residual abrasive coating, on the tip section of the airfoil. The supplemental abrasive coating restores the airfoil to a nominal tip height in the tip section.

Abrasive airfoil tip

A method for preparing a protectively coated, apertured article to be recoated reduces the likelihood that the apertures will become constricted as a consequence of subsequent recoating. The invention, described in the context of a gas turbine engine blade (,) having transpiration cooling passages (,), includes the step of diffusing an auxiliary coating (,) into an existing coating (,) and into the exposed substrate material (,) at the periphery of the passages to form a diffusion zone (,). The blade is then subjected to a stripping agent so that the diffusion zone (,) any undiffused existing coating, and any undiffused auxiliary coating are removed. The method causes a compensatory enlargement of the mouth (,) of each passage so that excess coating that accumulates in the passage mouths during subsequent recoating does not restrict the flow capacity of the passages.

Apertured article preconditioned for recoating

A method for preparing a protectively coated, apertured article to be recoated reduces the likelihood that the apertures will become constricted as a consequence of subsequent recoating. The invention, described in the context of a gas turbine engine blade (12) having transpiration cooling passages (34), includes the step of diffusing an auxiliary coating (52) into an existing coating (28) and into the exposed substrate material (26) at the periphery of the passages to form a diffusion zone (54). The blade is then subjected to a stripping agent so that the diffusion zone (54) any undiffused existing coating, and any undiffused auxiliary coating are removed. The method causes a compensatory enlargement of the mouth (44) of each passage so that excess coating that accumulates in the passage mouths during subsequent recoating does not restrict the flow capacity of the passages.

Method for preparing an apertured article to be recoated

A gas turbine engine component coated with a thermal barrier coating that includes a metallic bond coat and a ceramic top coat is repaired by removing the ceramic top coat from an engine-run gas turbine engine component and inspecting the component. A metallic flash coat is applied to at least a portion of the component. A ceramic top coat is then applied over predetermined portions of the component, including the portion to which the metallic flash coat was applied.

Repair of gas turbine engine component coated with a thermal barrier

Variable polarity welding is used to repair coated articles, particularly gas turbine engine components. The variable polarity welding process is found to remove the coating during the welding process. This permits the elimination of costly steps which would otherwise be needed in the repair process.

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Windsor Locks, CT, United States of America

Peter Wrabel