Aerostructure Coating Stack for Anodize Defect Sealing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Structural aluminum alloy components in gas turbine engines, such as stator vanes, are prone to corrosion due to their anodized protective films having defects like cracks and pinhole voids, which expose the substrate to environmental attack.

Innovation Solution

A multi-layer coating system comprising an anodize layer, a sealant primer, a second primer, and a polymeric topcoat is applied to the aluminum alloy substrate, with the sealant primer filling porosity and extending beyond the anodize layer to provide enhanced protection, and the second primer acting as a bonding intermediary and barrier, while the topcoat offers erosion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an anodized protective film is applied to aluminum alloy components, then corrosion resistance is improved, but the film develops defects like cracks and pinhole voids that expose the substrate to environmental attack

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidenvironmental attack through defects

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The protective coating is divided into multiple functional layers: anodized base layer, sealant layer, primer layer, and topcoat layer. Each layer addresses specific protection needs, with the sealant layer specifically targeting the pore defects in the anodized layer to prevent environmental attack while maintaining the overall corrosion resistance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The coating system uses a nested structure where the sealant layer is applied within and over the anodized layer pores, the primer layer is applied over the sealant layer, and the topcoat layer is applied over the primer layer. This nested arrangement ensures that each layer reinforces the protection provided by the previous layers while addressing specific vulnerability points.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If a multi-layer coating system is applied to seal defects and provide protection, then corrosion and erosion resistance are improved, but the coating system complexity increases

Engineering Contradiction:

Improvecorrosion and erosion resistanceVSAvoidcoating system structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The coating system is segmented into distinct functional layers, each with specific thickness ranges and purposes. The anodized layer (1-5 micrometers) provides base protection, the sealant layer fills pores, the primer layer (5-50 micrometers) provides intermediate protection and adhesion, and the topcoat layer (10 micrometers to 1 millimeter) provides erosion resistance. This segmentation allows each layer to be optimized for its specific function while maintaining overall system manageability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different layers of the coating system have different local qualities and properties tailored to specific protection needs. The anodized layer has porous structure for sealant infiltration, the sealant layer has high filler content for pore closure, the primer layer has adhesive properties for bonding, and the topcoat layer has erosion resistance. This local quality differentiation allows the system to address multiple protection requirements without unnecessary complexity in each individual layer.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The coating system effectively prevents corrosion and erosion by sealing defects in the anodized film, maintaining the structural integrity and durability of aluminum alloy components under harsh operating conditions.

Implementation Method 1

an anodize layer having a thickness (TA) of 1.0 to 5.0 micrometers

Methodology Applied

Scientific EffectAnodization: Anodising

Implementation Method 2

a sealant filling at least 5.0% of porosity in the anodize layer... a sealant primer filling 50.0% of porosity in the anodize layer

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS12560092B2Coating for aluminum alloy aerostructures

Publication Date: 2026.02.24 RTX CORP

AI summary

An airfoil element including an airfoil having a pressure side and a suction side, an aluminum alloy substrate and a coating system atop the substrate, said coating comprising in at least one location an anodize layer (24) having a thickness (TA) of 1.0 to 5.0 micrometer, a sealant (36) filling at least 5.0% of porosity in the anodize layer or at least 0.7% of an apparent volume within a height of the anodize layer, a sealant primer (40) filling 50.0% of porosity in the anodize layer or at least 6.5% of an apparent volume within a height of the anodize layer and extending at least flush to the anodize layer, a second primer (44) over the sealant primer having a thickness (TS) of 5.0 to 50 micrometer and a polymeric coating (48) having a thickness (TT) of 10.0 micrometer to 1.0 millimeter.