Nickel Superalloy Sublayer for Interdiffusion Control
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Solution Overview
Problem
Existing nickel-based superalloy parts coated with thermal barriers suffer from significant interdiffusion phenomena at high temperatures, leading to reduced lifetime due to corrosion and oxidation.
Innovation Solution
A nickel-based superalloy part with a metal sublayer comprising a first layer with a γ′-Ni3Al and γ-Ni phase, and a second layer with γ′-Ni3Al, γ-Ni, and β-NiAl phases, where the average aluminum content in the second layer is greater than in the first layer, minimizing interdiffusion and enhancing oxidation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nickel aluminide coatings with high aluminum content (around 40 atomic %) are used, then oxidation resistance is improved, but interdiffusion phenomena increase causing reduced lifetime
Solution Approach 1:
The coating is divided into two distinct layers: a first layer with lower aluminum content (15-30 atomic %) that interfaces with the substrate, and a second layer with higher aluminum content (30-45 atomic %) that provides oxidation resistance. This segmentation allows each layer to optimize its function without the harmful interdiffusion effects of a single high-aluminum coating.
Solution Approach 2:
Different aluminum contents are assigned to different regions of the coating. The first layer has moderate aluminum content to minimize interdiffusion at the substrate interface, while the second layer has high aluminum content to maximize oxidation resistance at the surface. This local differentiation resolves the contradiction between oxidation resistance and lifetime.
2Duration of action of stationary object
If γ-Ni/γ′-Ni3Al coatings with lower aluminum content (15-20 atomic %) are used, then interdiffusion phenomena are limited, but oxidation resistance decreases reducing lifetime
Solution Approach 1:
The coating is divided into two distinct layers: a first layer with lower aluminum content (15-30 atomic %) that interfaces with the substrate, and a second layer with higher aluminum content (30-45 atomic %) that provides oxidation resistance. This segmentation allows each layer to optimize its function without the harmful interdiffusion effects of a single high-aluminum coating.
Solution Approach 2:
The coating system functions as a composite structure combining two different aluminum-containing phases. The first layer provides adhesion and limits interdiffusion, while the second layer provides oxidation resistance. This composite approach achieves both low interdiffusion and high oxidation resistance simultaneously.
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 proposed sublayer structure effectively limits interdiffusion and enhances the oxidation resistance of nickel-based superalloy parts, thereby extending their lifespan in high-temperature environments.
Implementation Method 1
the diffusion phenomena which are thermally activated can induce significant modifications between the substrate and the sublayer on the substrates and their chemical compositions consequently reducing the lifetime of the whole part
Implementation Method 2
allows to form an alumina oxide that protects against corrosion and oxidation
Data Source
AI summary
A nickel-based superalloy part includes a nickel-based superalloy substrate, and a metal sublayer covering the substrate, wherein the metal sublayer includes a first and a second layer, the first layer being located between the substrate and the second layer, the first layer including a first γ′-Ni3Al phase and a second γ-Ni phase, the second layer including a first γ′-Ni3Al phase, a second γ-Ni phase and a third β-NiAl phase, the average atomic fraction of aluminum in the second layer being strictly greater than the average atomic fraction of aluminum in the first layer.