Sub-micron MCrAlY Coating Oxide Network for Gas Turbine Crack Resistance
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Solution Overview
Problem
Thermally loaded components in gas turbines face issues with cracking in bond coats due to low cycle fatigue and thermo-mechanical fatigue, leading to premature coating failure and reduced engine efficiency and lifetime, with existing solutions failing to extend both oxidation life and mechanical life simultaneously.
Innovation Solution
A method involving the application of a sub-micron structured MCrAlY coating layer using thermal spraying techniques, where sub-micron powder particles are surrounded by an oxide shell to form an interconnected oxide network, reducing cracking and improving mechanical and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard MCrAlY bond coat is used to protect thermally loaded components, then oxidation protection is provided, but cracking occurs due to low cycle fatigue and thermo-mechanical fatigue, reducing mechanical lifetime
Solution Approach 1:
The patent changes the microstructural parameters of the bond coat by incorporating sub-micron powder particles (0.1-10 µm) that form an interconnected oxide network during thermal spraying. This nanoscale structural modification fundamentally alters the coating's resistance to crack propagation while maintaining its oxidation protection function.
Solution Approach 2:
The patent creates a composite bond coat structure by combining sub-micron MCrAlY powder particles with conventional micron-sized particles. The sub-micron particles form an embedded oxide network that acts as a reinforcement phase, creating a composite material with superior mechanical properties and crack resistance compared to conventional homogeneous bond coats.
2Power
If the engine operating temperature is increased to improve efficiency, then energy output increases, but cracking in the bond coat accelerates, reducing component lifetime
Solution Approach 1:
The sub-micron oxide network is formed in advance during the thermal spraying process, creating a pre-established reinforcement structure that cushions and distributes thermal stresses before they can initiate or propagate cracks. This proactive structural reinforcement allows the component to withstand higher operating temperatures without premature failure.
Solution Approach 2:
The interconnected oxide network formed by sub-micron particles acts as an intermediary reinforcement phase between the metallic bond coat matrix and the ceramic top coat. This intermediate network mediates stress distribution and prevents direct stress concentration at the bond coat/top coat interface, enabling higher temperature operation.
3Duration of action of stationary object
If a thicker bond coat is applied to extend mechanical lifetime, then crack resistance improves, but oxidation protection decreases due to greater element depletion
Solution Approach 1:
The patent applies local quality enhancement by concentrating sub-micron particles strategically within the bond coat structure. These fine particles create localized oxide-rich regions that form a dense network at critical locations, providing enhanced crack resistance without requiring uniform thickening of the entire bond coat layer.
Solution Approach 2:
The bond coat is segmented into a composite structure with sub-micron particles distributed throughout the matrix. This segmentation creates numerous small oxide-forming centers that collectively provide enhanced mechanical properties without increasing overall coating thickness, thereby maintaining oxidation protection while improving crack resistance.
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 sub-micron structured coating layer enhances mechanical lifetime, reduces oxidation and corrosion, and provides self-healing characteristics, leading to extended service life and reduced scrap rates, while maintaining stability during operation.
Implementation Method 1
said sub-micron powder particles are each at least partially surrounded by an oxide shell and establish with their oxide shells an at least partially interconnected sub-micron oxide network within said coating layer
Implementation Method 2
applying said powder material to the surface of the component by means of a spraying technique to build up a coating layer
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention proposes a method for applying a high-temperature stable coating layer (12) on the surface of a component (11), comprising the steps of: a) providing a component (11) with a surface to be coated; b) providing a powder material containing at least a fraction of submicron powder particles (18); c) applying said powder material to the surface of the component (11) by means of a spraying technique to build up a coating layer (12), whereby d) said sub-micron powder particles (18) are each at least partially surrounded by an oxide shell (20) and establish with their oxide shells (20) an at least partially interconnected sub-micron oxide network (22) within said coating layer (12).