Tri-barrier ceramic coating for turbine thermal protection
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Solution Overview
Problem
Advanced turbine engine components face challenges due to high temperatures, where existing metallic coatings fail to protect against oxidation, overheating, erosion, and CMAS infiltration, leading to premature deterioration of thermal barrier coatings.
Innovation Solution
A tri-barrier ceramic coating system comprising a base thermal barrier layer, an intermediate CMAS barrier layer, and a top erosion barrier layer, applied using electron beam physical vapor deposition (EBPVD), with specific microstructures and layer thicknesses to provide thermal insulation, CMAS resistance, and erosion resistance without additional equipment costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single-layer thermal barrier coating is used to provide thermal insulation, then thermal protection is improved, but resistance to CMAS infiltration and erosion deteriorates
Solution Approach 1:
The coating system is divided into three distinct functional layers: a thermal barrier layer for thermal insulation, a CMAS barrier layer for chemical resistance, and an erosion barrier layer for mechanical protection. Each layer is optimized for its specific function, resolving the contradiction between thermal protection and CMAS/erosion resistance by separating these protective functions into independent segments.
Solution Approach 2:
The patent employs a composite coating structure combining different ceramic materials with complementary properties. The thermal barrier layer uses low thermal conductivity materials, the CMAS barrier layer uses chemically resistant materials, and the erosion barrier layer uses mechanically robust materials. This composite approach allows simultaneous achievement of thermal protection, CMAS resistance, and erosion resistance that cannot be obtained with a single material.
2Temperature
If thermal barrier coating thickness is increased to enhance thermal insulation, then thermal protection is improved, but coating complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of uniformly increasing coating thickness throughout, the patent applies different thicknesses to different functional layers based on their specific requirements. The thermal barrier layer thickness is optimized for thermal insulation, while the CMAS and erosion barrier layers have thinner but functionally sufficient thicknesses. This local optimization achieves necessary thermal protection without proportionally increasing overall coating complexity.
Solution Approach 2:
The multi-layer coating system is designed to provide multiple protective functions simultaneously through a single coating application process. The layered structure delivers thermal insulation, CMAS resistance, and erosion protection in one integrated system, avoiding the need for separate coatings for each function and thereby managing complexity efficiently.
3Temperature
If advanced ceramic materials are used to achieve lower thermal conductivity, then thermal protection is improved, but manufacturing precision and coating application difficulty increase
Solution Approach 1:
The patent optimizes various parameters including material composition ratios, layer thicknesses, and deposition conditions to achieve the desired thermal conductivity while maintaining manufacturability. By carefully controlling these parameters, the system achieves low thermal conductivity with advanced ceramics without sacrificing coating application precision or introducing excessive manufacturing 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 tri-barrier coating system effectively prevents CMAS infiltration, enhances erosion resistance, and reduces thermal conductivity, extending the lifespan of turbine engine components while offering a cost-effective solution for both CMAS and erosion protection.
Implementation Method 1
electron beam physical vapor deposition (EBPVD)
Implementation Method 2
thermal barrier layer... provide thermal insulation
Data Source
AI summary
A tri-barrier ceramic coating system is provided having a base thermal barrier layer, an intermediate CMAS barrier layer, and a top erosion barrier layer, and the method of applying such a coating system to a substrate. The base layer has a typical columnar structure with inter-columnar gaps and intra-columnar micro-pores that provides the stress tolerance during thermal cycles. The intermediate CMAS barrier layer has the fiber-like columns with inter-columnar nano-pores and a grid structure on the bottom of the layer. The fine structured intermediate layer covers the gaps between the columns of the base layer and will block CMAS infiltration effectively. The top erosion resistant layer contains wider TBC columns with narrow inter-columnar gaps and a modified cauliflower-like TBC head that provides erosion resistance for the underlying layers. The tri-barrier coating microstructure will further reduce the thermal conductivity as comparing to the conventional single layer system.