Compressor Seal-Ring Coating for High-Temperature Wear Resistance
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Solution Overview
Problem
Existing high-pressure compressor seal-ring assemblies made from nickel superalloys and coated with copper aluminum alloys fail prematurely due to poor tribological behavior under high temperature and vibratory conditions, leading to excessive wear and costly damage to counterface components in gas turbine engines.
Innovation Solution
A compressor seal-ring assembly with a lubricant coating comprising 75-98% wt. CoCrAlY and 2-25% wt. hBN, applied to both the seal ring and counterface, which reduces friction and wear through a Co-Co interface and additional hBN-based solid lubricant coatings, enhancing wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If nickel superalloy seal rings coated with copper aluminum alloy are used, then the seal can operate at elevated temperatures, but the tribological behavior deteriorates under high temperature and vibratory conditions causing premature wear failure
Solution Approach 1:
The patent applies a composite coating system consisting of multiple layers: a nickel superalloy substrate, a copper aluminum alloy intermediate layer, and a top coat of CoCrAlY or CoCrAlY-hBN composite material. This multi-layer composite structure combines the high-temperature resistance of nickel superalloy with the low-friction properties of CoCrAlY and the solid lubrication of hBN, resolving the contradiction between temperature capability and wear resistance
Solution Approach 2:
The patent changes the chemical composition and microstructure parameters of the coating by incorporating hexagonal boron nitride (hBN) particles into the CoCrAlY matrix. This parameter modification creates a composite material with enhanced lubrication properties and wear resistance while maintaining high-temperature stability, directly addressing the tribological failure mode
2Device complexity
If conventional copper aluminum alloy coating is applied to nickel superalloy seal rings, then the seal structure is simple, but the wear resistance is insufficient under harsh operating conditions
Solution Approach 1:
The patent transitions from a simple single-layer copper aluminum alloy coating to a complex multi-layer composite coating system. The CoCrAlY-hBN composite top coat provides superior wear resistance through the combination of metallic matrix strength and ceramic lubricant properties, justifying the increased structural complexity
Solution Approach 2:
The patent applies different materials with specific properties to different functional requirements: the copper aluminum alloy intermediate layer provides adhesion and initial lubrication, while the CoCrAlY-hBN top layer provides enhanced wear resistance and high-temperature stability. Each layer is optimized for its specific function, creating local quality improvements throughout the coating system
3Ease of operation
If seal rings operate under high vibratory motion conditions, then the sealing function is maintained, but the wear rate increases due to poor tribological behavior of the materials
Solution Approach 1:
The hBN particles act as solid lubricant intermediaries between the seal ring and counterface. Under high vibratory motion, these solid lubricant particles form a protective film that reduces direct metal-to-metal contact and friction, allowing the sealing function to be maintained while significantly reducing wear and extending service life
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 lubricant coating system significantly reduces wear on both the seal ring and counterface, extending the life of engine components and minimizing repair costs by creating a low-friction sliding regime, as demonstrated by reduced wear volume in comparative testing.
Implementation Method 1
A compressor seal-ring assembly with a lubricant coating comprising 75-98% wt. CoCrAlY and 2-25% wt. hBN, applied to both the seal ring and counterface, which reduces friction and wear through a Co-Co interface and additional hBN-based solid lubricant coatings
Data Source
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AI summary
A compressor seal-ring assembly includes a seal (40) formed of a nickel, cobalt or iron-based superalloy; a counterface (36) positioned for sealing interaction with the seal (40); and a lubricant coating (42) on the seal (40), the lubricant coating (42) being formed of a CoCrAlY-containing material.