Reinforced Bond Layer for Gas Turbine Thermal Barrier Coating
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Solution Overview
Problem
Gas turbine engine components experience cracking and delamination issues due to the degradation of thermal barrier coatings, particularly at the interface between the bond layer and the substrate, caused by the formation of a thermally grown oxide layer under high temperature and stress conditions, leading to reduced component lifetime and increased repair frequency.
Innovation Solution
A reinforced article is created with a substrate, a bond layer comprising bonding and reinforcing segments, and a protective layer, where the reinforcing segment is applied using electrospark deposition to reduce cracking and delamination by forming a metallurgical bond with the substrate and inhibiting the formation of thermally grown oxide layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling holes are drilled into the gas turbine engine component, then cooling efficiency is improved, but cracking and delamination occur at the interface between the bond layer and the substrate
Solution Approach 1:
The reinforcing segment is deposited on the substrate surface before the thermal barrier coating is applied and before cooling holes are drilled. This preliminary reinforcement prevents degradation at the bond layer-substrate interface during subsequent drilling operations, eliminating cracking and delamination while maintaining cooling efficiency.
Solution Approach 2:
The invention creates a composite structure by depositing a reinforcing segment (containing ceramic particles like alumina, silica, or chromia) within the bond layer material. This composite bond layer provides both adhesive bonding and enhanced resistance to cracking and delamination, allowing cooling holes to be drilled without compromising structural integrity.
2Object-affected harmful factors
If the thermal barrier coating is applied to protect the substrate, then oxidation resistance is improved, but the thermally grown oxide layer causes cracking and delamination under thermal stress
Solution Approach 1:
The reinforcing segment creates a composite bond layer that can accommodate thermal expansion differences between the substrate and protective layer. The ceramic particles in the reinforcing segment help manage thermal stress, preventing the TGO layer from creeping into the protective layer and causing delamination, while maintaining oxidation resistance.
Solution Approach 2:
The invention modifies the bond layer's physical and chemical properties by incorporating ceramic particles through electrospark deposition. This changes the bond layer's thermal conductivity, thermal expansion characteristics, and mechanical strength, allowing it to withstand thermal cycling and stress without cracking or delaminating.
3Strength
If the bond layer is made thicker to improve bonding strength, then adhesion is improved, but the component complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of uniformly increasing the entire bond layer thickness, the invention locally reinforces specific areas of the bond layer where cooling holes will be drilled or where stress concentration is expected. The reinforcing segment can be applied selectively to high-stress regions, providing enhanced bonding strength only where needed without increasing overall coating complexity.
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 reinforcing segment enhances the bonding strength and oxidation resistance of the bond layer, reducing cracking and delamination at the interfaces, thereby improving the component's performance and extending its operational lifetime by minimizing the frequency of repairs.
Implementation Method 1
the at least one reinforcing segment being formed on the surface of the substrate by electrospark deposition
Data Source
AI summary
An article comprising a substrate; a bond layer disposed on the substrate, the bond layer comprising one or more bonding segments and at least one reinforcing segment; at least one protective layer disposed on the bond layer; and at least one cooling hole extending through the substrate, the at least one reinforcing segment and the at least one protective layer, wherein the at least one reinforcing segment reduces cracking and/or delamination at the interface between the substrate and the bond layer, and methods of making the same.