Abrasive Tip Blade Coating Delamination Prevention
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Solution Overview
Problem
Existing abrasive tip coatings for turbomachines, such as gas turbine engines, face issues with delamination and peening effects due to the hardness difference between the substrate and the coating, leading to potential damage during rub interactions and vibration resonances, which affect the operational clearance and efficiency.
Innovation Solution
A method involving the application of an aluminum-based base layer, softer than the substrate, followed by a simultaneous spraying of an abrasive and aluminum-based matrix coating, where the base layer absorbs the impact of abrasive particles and reduces delamination, and the aluminum matrix provides galvanic protection and reduced modulus to minimize stress and heat generation during rub interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard abrasive coating is applied directly to the substrate, then the coating provides wear resistance and abrasion protection, but the hardness difference causes delamination and peening effects
Solution Approach 1:
The patent applies a composite coating structure consisting of a soft aluminum-based base layer and a hard abrasive-containing top coating. This composite structure combines materials with different properties: the soft base layer absorbs impact and reduces peening, while the hard top layer provides wear resistance. The interface between layers is designed to manage stress distribution, preventing delamination while maintaining both protection functions.
Solution Approach 2:
The patent changes the mechanical parameters of the coating system by introducing a base layer with significantly different hardness and modulus properties compared to both the substrate and the abrasive top layer. This parameter transition zone (soft layer between hard substrate and hard coating) modifies the stress distribution and reduces the harmful peening effect while maintaining overall coating integrity and adhesion.
2Stress or pressure
If the coating modulus is high to reduce deformation, then aerodynamic forces are better resisted, but vibration resonances and non-uniform rub response increase
Solution Approach 1:
The patent introduces a base layer with reduced modulus (softer material) between the rigid substrate and the abrasive coating. This parameter change creates a gradient structure that allows the overall coating system to better absorb vibrational energy and reduce resonances, while still maintaining sufficient stiffness at the abrasive layer to resist aerodynamic forces during operation.
3Reliability
If a softer base layer is used to reduce peening, then delamination is reduced, but the substrate may be more vulnerable to damage
Solution Approach 1:
The patent creates a three-layer composite protection system: the soft aluminum base layer absorbs impact and protects the substrate from direct peening damage, while the hard abrasive top layer provides wear resistance. This composite structure ensures that both the substrate and the coating are protected, with the base layer acting as a cushion that prevents stress concentration at the substrate-coating interface.
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 solution enhances the adhesion and durability of the coating, reduces delamination, and maintains the substrate's properties by absorbing the impact of abrasive particles, thereby improving the operational efficiency and reducing the risk of damage during rub interactions, while maintaining the substrate's integrity.
Implementation Method 1
the base layer absorbs the impact of abrasive particles and reduces delamination
Implementation Method 2
the aluminum matrix provides galvanic protection and reduced modulus to minimize stress and heat generation during rub interactions
Data Source
AI summary
A blade comprises an airfoil having a root end and a tip. A metallic substrate is along at least a portion of the airfoil. An abrasive tip coating comprises an abrasive and an aluminum-based matrix. An aluminum-based base layer is between the tip coating and the substrate.