Nickel Aluminide Underlayer with Cu or Ag Stabilizers
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Solution Overview
Problem
Current thermal-barrier systems for turbine engine components face limitations in thermomechanical strength and oxidation resistance, leading to premature cracking and spalling, with existing solutions either compromising one aspect over the other or being costly.
Innovation Solution
A metal underlayer composed of nickel aluminide with 0.5 to 0.95 atomic percent of stabilizer elements like Cu or Ag is used, which enhances the microstructure stability, reduces oxidation, and maintains a low surface roughness, thereby improving the thermomechanical strength and oxidation resistance of the coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional metal underlayer is used without stabilizer elements, then the coating can be applied, but the microstructure becomes unstable at high temperatures leading to premature cracking and spalling
Solution Approach 1:
The patent modifies the chemical composition parameters of the metal underlayer by incorporating stabilizer elements (Ti, Nb, Ta, Hf, Zr, or La) at specific concentrations (0.01-5 wt% for each element, with total stabilizer content controlled). This parameter change stabilizes the gamma and gamma prime phases at high temperatures, preventing microstructural degradation and extending service lifetime while maintaining coating reliability.
Solution Approach 2:
The patent creates a composite metal underlayer by combining nickel aluminide base material with multiple stabilizer elements. This composite structure provides both the protective functionality of nickel aluminide and the microstructural stability conferred by the stabilizer elements, resolving the contradiction between coating application and long-term durability.
2Reliability
If the metal underlayer composition is modified with stabilizer elements, then microstructure stability and oxidation resistance improve, but manufacturing complexity increases
Solution Approach 1:
The patent specifies precise parameter ranges for stabilizer element content (0.01-5 wt% per element) to optimize oxidation resistance while controlling manufacturing complexity. By defining clear compositional boundaries, the patent makes the complex multi-element alloy manageable for conventional manufacturing processes.
3Temperature
If existing thermal barrier solutions are used, then gas inlet temperature can be increased, but thermomechanical strength and oxidation resistance are compromised leading to premature failure
Solution Approach 1:
The patent modifies the metal underlayer composition parameters by adding stabilizer elements that maintain microstructural stability at elevated temperatures. This enables the thermal barrier system to operate at higher gas inlet temperatures while preserving thermomechanical strength and oxidation resistance, preventing premature failure.
Solution Approach 2:
The patent employs a composite metal underlayer structure combining nickel aluminide with stabilizer elements to achieve both high-temperature strength and oxidation resistance. This composite approach allows the thermal barrier to withstand higher temperatures without compromising reliability.
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 modified metal underlayer composition results in a more stable and longer-lasting coating with improved resistance to spalling and oxidation, maintaining a low surface roughness and reducing defects, thus extending the service lifetime of turbine components.
Implementation Method 1
a metal underlayer which comprises a nickel aluminide base and also comprises 0.5 atomic percent (at %) to 0.95 at % of a stabilizer element M from the group formed by Cu and Ag for stabilizing the gamma and gamma prime phases
Implementation Method 2
adhesion between the underlayer and the substrate of the part takes place by inter-diffusion
Implementation Method 3
adhesion between the underlayer and the ceramic layer takes place by mechanical anchoring and by the propensity of the underlayer at high temperature to develop a thin oxide layer at the ceramic and underlayer interface
Implementation Method 4
This insulating coating serves to create a temperature gradient through the coating on a part that is being cooled during steady operating conditions
Implementation Method 5
presenting conductivity of 1.1 watts per meter per kelvin (W.m−1.K−1)
Implementation Method 6
this metal underlayer provides the superalloy of the part with protection against corrosion and oxidation phenomena
Data Source
AI summary
The invention relates to a part comprising a coating on a superalloy metal substrate, the coating comprising a metal underlayer covering said substrate, the part being characterized in that said metal underlayer contains a base of nickel aluminide and also contains 0.5 at % to 0.95 at % of one or more stabilizer elements M from the group formed by Cu and Ag for stabilizing the gamma and gamma prime phases.