Oxidation-Resistant Coated Superalloy for Turbine Blades
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Solution Overview
Problem
High-temperature nickel-based superalloys used in turbine engine turbine blades are prone to oxidation and exhibit excessive secondary reaction zone (SRZ) formation, which compromises mechanical properties such as fatigue and creep resistance.
Innovation Solution
A coating-substrate combination is developed using a Ni-based superalloy substrate with specific weight percent compositions and a coating comprising predominantly Ni, with optimized contents of Al, Cr, Co, Ta, W, Re, Ru, Hf, Si, Y, and Zr, applied via physical vapor deposition, which minimizes SRZ formation and enhances oxidation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxidation-resistant coatings are applied to nickel-based superalloy turbine blades, then oxidation resistance is improved, but excessive secondary reaction zone (SRZ) formation occurs which compromises mechanical properties
Solution Approach 1:
The invention applies parameter changes by precisely controlling the composition ranges of multiple alloying elements in both the substrate and coating. The substrate contains specific weight percentages of Cr (2.0-5.1%), Mo (0.9-3.3%), W (3.9-9.8%), Ta (2.2-6.8%), Al (5.4-6.5%), Co (1.8-12.8%), Re (2.8-5.8%), and Ru (2.8-7.2%), while the coating contains Ni as the largest content with Al (5.8-9.3%), Cr (4.4-25%), Co (3.0-13.5%), and other elements within specified ranges. This compositional parameter optimization minimizes harmful SRZ formation while maintaining oxidation resistance.
Solution Approach 2:
The invention uses composite materials by creating a multi-layered coating-substrate system where each layer has optimized composition. The coating layer contains Ni-based alloy with specific proportions of Al, Cr, Co, and trace elements (Hf, Si, Y, Zr, Re), while the substrate contains a different optimized composition. This composite structure allows the coating to provide oxidation protection while the substrate maintains mechanical strength, and the controlled composition minimizes intermediate SRZ formation at the interface.
2Reliability
If conventional coatings are used to protect superalloy substrates, then oxidation resistance is enhanced, but SRZ thickness increases excessively
Solution Approach 1:
The invention applies parameter changes by optimizing the compositional parameters of both coating and substrate to control diffusion processes. The coating contains Al (5.8-9.3%), Cr (4.4-25%), and trace elements (Hf: 0.3-0.6%, Si: 0.1-0.4%, Y: up to 0.6%, Zr: up to 0.4%, Re: up to 1.0%), while the substrate contains controlled amounts of Cr (2.0-5.1%), Mo (0.9-3.3%), W (3.9-9.8%), Ta (2.2-6.8%), and other elements. This precise parameter control minimizes element diffusion across the interface, thereby reducing SRZ thickness while maintaining protection.
3Power
If turbine blades operate at elevated temperatures for extended periods, then power generation efficiency is improved, but oxidation and mechanical degradation accelerate
Solution Approach 1:
The invention uses composite materials to create a turbine blade system that can withstand elevated temperatures. The coating layer with Ni-based alloy containing Al (5.8-9.3%), Cr (4.4-25%), Co (3.0-13.5%), and trace elements provides oxidation and environmental protection, allowing the blade to operate at high temperatures. The substrate with optimized composition provides high-temperature strength and creep resistance. The controlled SRZ minimization ensures interface integrity under thermal stress, enabling sustained power generation at elevated temperatures.
Solution Approach 2:
The invention applies parameter changes by optimizing the chemical composition parameters of the coating-substrate system to maintain mechanical properties at elevated temperatures. The substrate contains Cr (2.0-5.1%), Mo (0.9-3.3%), W (3.9-9.8%), Ta (2.2-6.8%), Al (5.4-6.5%), Co (1.8-12.8%), Re (2.8-5.8%), and Ru (2.8-7.2%), while the coating contains Ni with Al (5.8-9.3%), Cr (4.4-25%), Co (3.0-13.5%), and trace elements. This compositional optimization maintains strength and creep resistance at high operating temperatures.
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 solution significantly reduces SRZ thickness, thereby improving the mechanical properties and oxidation resistance of the superalloy, maintaining strength and creep resistance even at elevated temperatures for extended periods.
Implementation Method 1
A coating-substrate combination is developed using a Ni-based superalloy substrate with specific weight percent compositions and a coating comprising predominantly Ni, with optimized contents of Al, Cr, Co, Ta, W, Re, Ru, Hf, Si, Y, and Zr, applied via physical vapor deposition
Implementation Method 2
The solution significantly reduces SRZ thickness, thereby improving the mechanical properties and oxidation resistance of the superalloy, maintaining strength and creep resistance even at elevated temperatures for extended periods
Data Source
AI summary
A coating-substrate combination includes: a Ni-based superalloy substrate comprising, by weight percent: 2.0-5.1 Cr; 0.9-3.3 Mo; 3.9-9.8 W; 2.2-6.8 Ta; 5.4-6.5 Al; 1.8-12.8 Co; 2.8-5.8 Re; 2.8-7.2 Ru; and a coating comprising, exclusive of Pt group elements, by weight percent: Ni as a largest content; 5.8-9.3 Al; 4.4-25 Cr; 3.0-13.5 Co; up to 6.0 Ta, if any; up to 6.2 W, if any; up to 2.4 Mo, if any; 0.3-0.6 Hf; 0.1-0.4 Si; up to 0.6 Y, if any; up to 0.4 Zr, if any; up to 1.0 Re, if any.