Multilayer TBC Coating for Gas Turbine CMAS Resistance
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Solution Overview
Problem
Current high temperature coating systems for gas turbine engine (GTE) components lack sufficient thermal insulation, oxidation resistance, sinter resistance, fracture resistance, and resistance to Calcium-Magnesium Aluminosilicates (CMAS) attack, limiting their performance and lifespan at elevated temperatures.
Innovation Solution
A multilayer coating system comprising a fracture-resistant TBC layer with zirconia and tantala, and a CMAS-resistant TBC layer with zirconia, tantala, and rare earth oxides, where the CMAS-resistant layer is formulated to provide enhanced protection against CMAS attack and chemical compatibility with the fracture-resistant layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single layer TBC coating is formed, then the coating structure is simple, but the thermal insulation, oxidation resistance, sinter resistance, fracture resistance, and CMAS resistance are insufficient
Solution Approach 1:
The coating system is divided into multiple functional layers: a TBC layer providing thermal insulation, an EBC layer providing chemical barrier protection, and a bond coat layer providing adhesion and oxidation resistance. Each layer performs a specific function, collectively achieving comprehensive protection that a single layer cannot provide.
Solution Approach 2:
The patent employs composite coating structures combining different materials with complementary properties. The TBC layer uses zirconia-based materials for thermal insulation, the EBC layer uses rare earth oxides for chemical resistance, and the bond coat uses aluminide or MCrAlX alloys for adhesion and oxidation protection, creating a composite system that addresses multiple degradation mechanisms simultaneously.
2Productivity
If core gas temperatures are increased to enhance GTE performance, then GTE efficiency improves, but component surface temperatures and gas velocities increase, accelerating high temperature failure modes
Solution Approach 1:
The coating system is applied beforehand to GTE components to create a protective barrier against high temperature degradation. The TBC layer provides thermal insulation to reduce surface temperatures, while the EBC layer provides chemical barrier protection against CMAS attack and oxidation, cushioning the component against thermal and chemical stresses before they can cause damage.
Solution Approach 2:
The coating system acts as an intermediary layer between the hot gas environment and the GTE component. It mediates the interaction by providing thermal insulation to reduce heat transfer to the component, chemical barrier protection against CMAS and oxidation, and mechanical protection against thermal stress, enabling the component to withstand higher operating temperatures.
3Reliability
If TBCs are formed on GTE components to thermally insulate them, then high temperature failure modes are prevented, but the coating system remains limited in providing simultaneous thermal insulation, oxidation resistance, sinter resistance, and CMAS resistance
Solution Approach 1:
The coating system is segmented into specialized layers: the TBC layer focuses on thermal insulation, the EBC layer focuses on chemical barrier protection against oxidation and CMAS, and the bond coat focuses on adhesion and oxidation resistance at the substrate interface. This segmentation allows each layer to be optimized for its specific function while collectively providing comprehensive protection.
Solution Approach 2:
The coating system achieves multi-functionality by combining layers with complementary properties. The TBC layer provides thermal insulation, the EBC layer provides chemical resistance to oxidation and CMAS attack, and the bond coat provides adhesion and oxidation protection. Together, these layers create a universal protective system that addresses multiple degradation mechanisms simultaneously, enabling the coating to adapt to various high temperature failure modes.
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 offers improved thermal insulation, oxidation resistance, fracture resistance, and CMAS resistance, extending the lifespan of GTE components and enabling operation at higher temperatures with reduced maintenance requirements.
Implementation Method 1
TBCs may be formed on selected GTE components to thermally insulate the component bodies from elevated surface temperatures
Implementation Method 2
EB-PVD—Electron Beam Physical Vapor Deposition
Data Source
AI summary
Methods for forming high temperature coating systems are provided. In embodiments, the coating formation method includes forming a fracture-resistant Thermal Barrier Coating (TBC) layer over a workpiece surface. The fracture-resistant TBC layer is produced from a first coating precursor material containing an amount of zirconia in mole percent (ZrOmol%1) and an amount of tantala in mole percent (TaOmol%1). A Calcium-Magnesium Aluminosilicate (CMAS) resistant TBC layer is formed over the fracture-resistant TBC layer from a second coating precursor material, which contains an amount of zirconia in mole percent (ZrOmol%2), an amount of tantala in mole percent (TaOmol%2), and an amount of one or more rare earth oxides in mole percent (REOmol%2). The first and second coating precursor materials are formulated such that ZrOmol%1 is greater than ZrOmol%2, TaOmol%1 is less than TaOmol%2, and TaOmol%2 is substantially equivalent to REOmol%2.