Nanocrystalline Interlayer for Thermal Barrier Coating Spallation
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Solution Overview
Problem
Thermal barrier coatings (TBCs) on gas turbine components face spallation and reduced service life due to thermally grown oxide (TGO) growth and internal oxidation of bond coats, leading to cracking and delamination, especially under thermal cycling conditions.
Innovation Solution
A nanocrystalline MCrAl(X) interlayer coating is applied between the conventional bond coat and the YSZ thermal barrier coating, using methods like plasma enhanced magnetron sputter deposition, to slow down TGO growth and delay the formation of non-Al2O3 oxides, thereby extending the service life of the coated components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a conventional bond coat is used without an interlayer, then the coating structure is simple and manufacturing is easier, but the thermally grown oxide grows rapidly and service life is reduced
Solution Approach 1:
The bond coat system is segmented into two distinct layers: a conventional bond coat layer and a nanocrystalline interlayer. This segmentation allows each layer to perform its specific function - the bond coat provides oxidation resistance while the interlayer controls TGO growth, thereby extending service life without excessive complexity
Solution Approach 2:
A nanocrystalline interlayer is introduced as an intermediary between the conventional bond coat and the YSZ thermal barrier coating. This interlayer acts as a mediator that slows down TGO growth and delays non-Al2O3 oxide formation, protecting the TBC system from spallation while maintaining a manageable multi-layer structure
2Use of energy by moving object
If cooling airflow is reduced to improve turbine efficiency, then energy efficiency increases, but the reliability of the YSZ thermal barrier coating decreases
Solution Approach 1:
The nanocrystalline interlayer is applied in advance during the coating manufacturing process to preemptively control TGO growth kinetics. This preliminary action ensures that the TBC system maintains high reliability even under reduced cooling conditions, allowing turbine efficiency to be improved without compromising coating reliability
3Object-affected harmful factors
If thermal barrier coating is applied to protect from high temperature, then protection from combustion gases is improved, but thermally grown oxide growth causes cracking and spallation
Solution Approach 1:
The nanocrystalline interlayer serves as a protective intermediary that mediates between the bond coat and TBC, controlling TGO growth to prevent cracking and spallation while maintaining protection from combustion gases
Solution Approach 2:
The interlayer changes the physical and chemical parameters of the bond coat interface by providing a nanocrystalline structure that slows oxidation kinetics and delays non-Al2O3 oxide formation, thereby maintaining coating integrity under high temperature exposure
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 nanocrystalline interlayer significantly reduces TGO growth rate, delays non-Al2O3 oxide formation, and doubles the oxidation service life of the bond coat, reducing the risk of YSZ spallation and extending the maintenance interval of gas turbine components.
Implementation Method 1
A nanocrystalline MCrAl(X) interlayer coating is applied between the conventional bond coat and the YSZ thermal barrier coating, using methods like plasma enhanced magnetron sputter deposition, to slow down TGO growth and delay the formation of non-Al2O3 oxides
Implementation Method 2
A nanocrystalline MCrAl(X) interlayer coating is applied between the conventional bond coat and the YSZ thermal barrier coating, using methods like plasma enhanced magnetron sputter deposition
Data Source
AI summary
A coated substrate including a substrate having a surface, a bond coat proximate to the substrate surface, a yttrium stabilized zirconia (YSZ) thermal barrier layer opposite the substrate surface, and at least one interlayer disposed between the bond coat and the thermal barrier layer, wherein the interlayer contains an alloy having a nanocrystalline grain structure. A method for coating a substrate to be exposed to high in service temperatures and/or temperature cycles including depositing a bond coating on substrate surface, depositing at least one nanocrystalline interlayer on the bond coat opposite the substrate surface, and depositing a yttrium stabilized zirconia (YSZ) thermal barrier coating on the nanocrystalline interlayer opposite the bond coat, wherein the service life of the YSZ thermal barrier coating is extended relative to a substrate coated with the bond coating and the thermal barrier without the interlayer disposed therebetween.