Oxidation and Wear Resistant Coating for Gas Turbines
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Solution Overview
Problem
Gas turbine components face mechanical and oxidation wear due to high temperatures and mechanical contact, leading to coating degradation and reduced longevity, with existing coatings failing to provide adequate protection against beta depletion and erosion.
Innovation Solution
A thermal spray process is used to apply a combination of hardfacing material and aluminum-containing particles, forming a self-limiting oxide layer that reduces oxidation and mechanical wear, enhancing the durability of the coating by forming a thin, protective aluminum oxide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a coating is applied to protect against mechanical wear, then mechanical wear resistance is improved, but oxidation resistance at high temperatures deteriorates
Solution Approach 1:
The patent applies a composite coating system consisting of multiple layers: a base alloy coating (e.g., CoNiCrAlY) containing both mechanical wear resistance and oxidation resistance elements, and a top layer of aluminum-containing material (e.g., aluminum oxide or aluminum-based alloy) that forms a protective oxide scale. This composite structure allows the base layer to provide mechanical strength and wear resistance while the aluminum-containing top layer provides oxidation resistance through formation of a self-healing protective oxide scale, thereby resolving the contradiction between mechanical wear resistance and oxidation resistance.
2Strength
If the coating thickness is increased to improve wear resistance, then mechanical wear resistance is improved, but the consumption of hardfacing material increases
Solution Approach 1:
The patent applies local quality by creating a specialized top layer of aluminum-containing material specifically at the surface where oxidation occurs, while the base alloy coating provides mechanical wear resistance. This localized differentiation allows the aluminum-containing top layer to form a protective oxide scale that prevents further oxidation and reduces material consumption, while the base layer maintains the necessary mechanical properties without requiring excessive thickness.
3Reliability
If a thick oxide layer is formed to protect against oxidation, then oxidation resistance is improved, but mechanical wear resistance deteriorates
Solution Approach 1:
The patent controls the thickness and composition parameters of the oxide layer by using aluminum-containing materials that form a thin, adherent, and protective oxide scale (typically 1-10 micrometers) rather than allowing thick oxide formation. The aluminum-containing top layer reacts with oxygen to form a thin protective Al2O3 scale that provides excellent oxidation resistance while maintaining mechanical integrity and wear resistance, thereby resolving the contradiction between oxidation resistance and mechanical wear resistance.
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 significantly extends the service life of gas turbine components by reducing oxidation and mechanical wear, maintaining mechanical wear resistance for a longer duration while minimizing the consumption of the hardfacing material, thus reducing operational costs and the need for reapplication or replacement.
Implementation Method 1
applying a material coating to a surface of a machine component using a thermal spray
Implementation Method 2
thermally treating the material coating to generate an oxide layer comprising aluminum from the aluminum-containing particles
Data Source
AI summary
A method includes applying a material coating on a surface of a machine component using a thermal spray, wherein the material coating is formed from a combination of a hardfacing material and aluminum-containing particles. The method also includes thermally treating the material coating to generate an oxide layer comprising aluminum from the aluminum-containing particles, wherein the oxide layer is configured to reduce oxidation of the hardfacing material.