EP3184180B1

EP3184180B1 - Local repair or remanufacture of polymeric erosion coatings

Info

Publication number: EP3184180B1
Application number: EP16204712.0A
Authority: EP
Inventors: William Bogue; Dorel M. Moisei; Bruce R. SAXTON; John D. Riehl; Xiaomei Fang; William J. Brindley
Original assignee: United Technologies Corp
Current assignee: RTX Corp
Priority date: 2015-12-24
Filing date: 2016-12-16
Publication date: 2020-06-10
Anticipated expiration: 2036-12-16
Also published as: EP3184180A1

Description

BACKGROUND

The present disclosure relates generally to a remanufactures process and, more particularly, to a repair process for aluminum fan blades.
Gas turbine engines, such as those that power modern commercial and military aircraft, generally include a fan section, a compressor section to pressurize an airflow, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases.
The fan section often includes aluminum fan blades designed with a multi-layer polyurethane erosion coating to protect both sides of the airfoil from operational erosion and subsequent corrosion. The erosion coatings sustain erosion, FOD and local damage in service, but there is only minimal repair capability for these coatings.
Methods of locally repairing multi-layered erosion coatings are known from US 6,171,704 B1 and US 2005/0019589 . Therein multi-layered coatings are repaired by applying a filled epoxy paste without the prior application of a paint primer in the damaged areas.

SUMMARY

A method according to one aspect of the present invention is defined in claim 1. A corresponding component with a local repair to a multi-layered polyurethane erosion coating according to another aspect of the present invention is defined in claim 5. Preferred embodiments are referred to in the dependent claims.
The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation of the invention will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:

Figure 1 is a general schematic view of an exemplary component as a representative workpiece;
Figure 2 is an expanded cross section of the component illustrating the OEM coating system; and
Figure 3 is an expanded cross section of a repair to the component illustrating the repair coating system

DETAILED DESCRIPTION

Figure 1 schematically illustrates a general perspective view of an exemplary component 20, e.g., a fan blade with a multi-layer erosion coating system for a gas turbine engine. It should be appreciated that although a particular component type is illustrated in the disclosed non-limiting embodiment, other components with a multi-layer erosion coating system such as a part in the airstream of the engine with an erosion resistant coating, more specifically an airfoil, and even more specifically, a guide vane or a fan blade will also benefit herefrom.
With reference to Figure 2, a cross-section of the component 20 is illustrated for an aluminum substrate 30 such as a 2000, 6000, or 7000 series aluminum with a multi-layer coating 35. It should be appreciated other materials such as titanium may be provided. The coating 35 includes a phosphoric acid anodize layer 40, a corrosion inhibiting epoxy bond primer 50, a corrosion inhibiting paint primer 60, and an elastomeric erosion coating 70 such as a urethane or fluoroelastomer as the outer layer. It should be appreciated that various materials may be utilized in accords with this layer structure.
With reference to Figure 3, a local repair 100 for the component 20 is performed on an airflow surface. That is, the local repair of damage is performed in response to damage into the erosion coating system 35 and as deep as the aluminum substrate 30. The local repair 100 may be initiated by abrading thru some or all layers in the erosion coating system and may be as deep as the aluminum substrate 30 or for damage that has reached down to the aluminum substrate 30. The erosion coating system adjacent to the damage may be abraded, feathered or otherwise prepared and cleaned with, for example aluminum oxide and an acetone wipe to provide for adhesion of the repair coating system .
Next, the corrosion inhibiting paint primer 60 is applied over the aluminum substrate 30. The corrosion inhibiting paint primer 60 provide corrosion protection to the aluminum substrate 30 and also facilitates receipt of a filled epoxy paste 200 such as Duralco 4525 manufactured by Cotronics Corp., of Brooklyn NY USA. It is recognized that for other composite or metallic substrates, the paint primer may not need to provide corrosion protection to the substrate and the use of the primer layer may be optional or a non-corrosion inhibiting primer may be utilized. The epoxy paste provides for relatively faster thickness build rates than elastomeric coating material options facilitating faster overall repair process times. The filled epoxy paste 200 may then be sanded or otherwise finished to provide an acceptable flowpath surface.
The filled epoxy paste 200 facilitates field repairs, provides erosion protection and protects primer layers within the repair coating system.
The use of the terms "a," "an," "the," and similar references in the context of description (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or specifically contradicted by context. The modifier "about" used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity). All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. It should be appreciated that relative positional terms such as "forward," "aft," "upper," "lower," "above," "below," and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting.
Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.
It should be appreciated that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be appreciated that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom.
The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be appreciated that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.

Claims

A method for local repair to a damaged area of a multi-layer polyurethane erosion coating system on an airfoil surface of a fan blade, comprising:
preparing the erosion coating adjacent to the damage by abrading and/or feathering; and cleaning the erosion coating adjacent to the damage;

applying a paint primer onto a substrate in the damaged area; and

applying a filled epoxy paste to the paint primer in the damaged area.
The method as recited in claim 1, wherein preparing the erosion coating system adjacent to the damaged area comprises abrading the erosion coating down to the substrate, wherein the substrate for the erosion coating system is an aluminum substrate.
The method as recited in claim 1, wherein preparing the multi-layer polyurethane erosion coating system adjacent to the damaged area comprises feathering the erosion coating into the airfoil surface adjacent to the damaged area.
The method as recited in claim 1, wherein the substrate for the erosion coating system is an aluminum substrate and the multi-layer polyurethane erosion coating on the substrate comprises a phosphoric acid anodize layer, a corrosion inhibiting epoxy bond primer, a corrosion inhibiting paint primer, and an elastomeric erosion coating as the outer layer.
A component with a local repair to a multi-layer polyurethane erosion coating, comprising:
a local area of missing multi-layer polyurethane erosion coating, the local area filled with a filled epoxy paste over a substrate that forms an airfoil surface, and further comprising a paint primer between the filled epoxy paste and the substrate.
The component as recited in claim 5, wherein the substrate for the erosion coating system is an aluminum substrate and the multi-layer polyurethane erosion coating comprises a phosphoric acid anodize layer, a corrosion inhibiting epoxy bond primer, a corrosion inhibiting paint primer, and an elastomeric erosion coating, the elastomeric erosion coating as the outer layer.
The component as recited in any one of claims 5-6 wherein said component is a gas turbine engine component.
The component as recited in claim 7 wherein said component is a part in the airstream of the engine.
The component as recited in any one of claims 5 to 8 wherein said component is an airfoil.
The component as recited in any one of claims 5 to 9 wherein said component is a guide vane or a fan blade.