Cobalt-Modified Beta-Nickel-Aluminide Coating for Superalloy Interdiffusion
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Solution Overview
Problem
Nickel-base superalloys used as carriers for ceramic matrix composites in gas turbine engines face interdiffusion issues, leading to the formation of brittle intermetallic phases due to elemental exchange, which can cause component failure.
Innovation Solution
A cobalt-modified beta-nickel-aluminide coating is applied to the nickel-base superalloy substrate, comprising steps of depositing a cobalt layer, an aluminium layer, and forming a beta-nickel-aluminide layer to prevent interdiffusion between the substrate and the ceramic matrix composite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If nickel-base superalloy is used as carrier for CMC components, then high temperature creep and oxidation performance is achieved, but interdiffusion of elements forms brittle intermetallic phases causing component failure
Solution Approach 1:
A cobalt-modified beta-nickel-aluminide intermediate layer is introduced between the nickel-base superalloy carrier and the SiC/SiC CMC seal segments. This intermediate layer acts as a diffusion barrier that prevents interdiffusion of nickel into silicon and silicon into nickel, thereby preventing formation of brittle intermetallic phases while allowing the system to operate at high temperatures. The cobalt modification enhances the protective capability of the beta-nickel-aluminide layer against interdiffusion.
2Reliability
If cobalt-modified beta-nickel-aluminide coating is applied, then interdiffusion prevention is achieved, but coating complexity increases
Solution Approach 1:
The coating structure is optimized by controlling the concentration of cobalt within a specific range (0.1-10 wt%) in the beta-nickel-aluminide layer. This parameter control approach achieves effective interdiffusion prevention while avoiding excessive complexity. The cobalt content is carefully regulated to provide sufficient protective function without creating an overly complex multi-layer or highly composite structure.
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 cobalt-modified beta-nickel-aluminide coating effectively prevents interdiffusion of nickel and silicon, enhancing wear resistance and maintaining high performance in resistance to hot corrosion and oxidation, unlike other modified beta nickel aluminide coatings.
Implementation Method 1
depositing a cobalt layer on the substrate; depositing an aluminium layer on the cobalt layer
Implementation Method 2
a cobalt-modified beta-nickel-aluminide coating on the substrate to prevent interdiffusion between the substrate and the ceramic matrix composite
Data Source
AI summary
An arrangement comprising a component (203) adjacent to a ceramic matrix composite in a gas turbine engine is shown. The component comprises a nickel-base superalloy substrate (301) and a cobalt-modified beta-nickel-aluminide coating (302) on the substrate to prevent interdiffusion between the substrate and the ceramic matrix composite. The substrate is coated by depositing a cobalt layer on the substrate, depositing an aluminium layer on the cobalt layer and then forming a cobalt-modified beta nickel aluminide coating.