Amorphous Silicon Bond Coating for Gas Turbine Oxidation Resistance
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Solution Overview
Problem
Current silicon bond coatings for ceramic components in high-temperature environments, such as gas turbine engines, suffer from linear defects and microstructural features that lead to low cohesive strength and oxidation of the substrate, resulting in blistering and delamination of environmental barrier coatings.
Innovation Solution
A silicon-based bond coating with an amorphous phase containing crystalline silicon grains, formed through chemical vapor deposition at low temperatures and subsequent heat treatment, providing enhanced cohesive strength and preventing oxygen penetration without releasing gas products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silicon bond coating is manufactured via air plasma spray, then the coating can be formed, but the coating contains microstructural features that result in low cohesive strength
Solution Approach 1:
The patent changes the manufacturing parameters by using chemical vapor deposition (CVD) instead of air plasma spray, and by controlling the deposition temperature and heat treatment conditions to achieve an amorphous microstructure with fine crystalline grains, thereby improving cohesive strength
Solution Approach 2:
The patent creates a composite microstructure within the silicon bond coat by combining an amorphous silicon phase with dispersed crystalline silicon grains, achieving both strong adhesion and high cohesive strength
2Strength
If silicon bond coating is manufactured via chemical vapor deposition, then the coating can be formed, but the coating has large grain size in EBC systems leading to reduced mechanical capability
Solution Approach 1:
The patent controls the deposition temperature during CVD to prevent excessive grain growth, and uses subsequent heat treatment at controlled temperatures to achieve fine crystalline grain size within the amorphous matrix, maintaining high mechanical capability
Solution Approach 2:
The patent creates different microstructural zones within the bond coat by controlling the deposition and heat treatment processes, resulting in fine crystalline grains dispersed in an amorphous matrix, where each phase contributes differently to the overall mechanical properties
3Reliability
If linear defects are present in silicon bond coat, then the coating structure is simplified, but oxidation protection fails at defect locations leading to substrate oxidation and blistering
Solution Approach 1:
The patent creates a composite structure with amorphous silicon and crystalline silicon grains that work together to provide oxidation protection, where the amorphous phase fills potential defect sites and the crystalline grains provide stable oxidation resistance
Solution Approach 2:
The patent optimizes the deposition and heat treatment parameters to create a dense, defect-free amorphous silicon bond coat with fine crystalline grains, eliminating linear defects that would compromise oxidation protection
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 amorphous silicon bond coating with crystalline silicon grains offers improved mechanical strength and prevents substrate oxidation, enhancing the durability and integrity of environmental barrier coatings in high-temperature applications.
Implementation Method 1
The silicon bond coating provides a layer that oxidizes (forming a passive silicon oxide layer beneath the EBC) without liberating a gaseous by-product
Implementation Method 2
formed through chemical vapor deposition at low temperatures
Implementation Method 3
subsequent heat treatment, providing enhanced cohesive strength
Data Source
AI summary
Methods of forming a coated component are provided. The coated component includes a substrate having a surface; a silicon-based bond coating on the surface of the substrate; and a barrier coating on the silicon-based bond coating. The silicon-based bond coating comprises amorphous silicon phase having grains of crystalline silicon (e.g., having an average size of about 0.03 μm to about 3 μm) distributed therein. The amorphous silicon phase may be formed of pure silicon metal, or may be formed from silicon metal with boron, oxygen, and/or nitrogen dispersed therein.