Ternary Oxide Coated Piston Seal for Gas Turbine Wear
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Solution Overview
Problem
Piston rings in gas turbine engines experience significant wear and creep due to high temperatures and vibratory motion, despite using nickel-based superalloys, which leads to increased friction and damage.
Innovation Solution
A piston seal assembly featuring a nickel-based superalloy with a ternary oxide coating, such as silver-based, copper-based, or calcium-based ternary oxides, that forms nanoparticles to act as a solid lubricant, reducing friction and wear at high temperatures and vibratory conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If nickel-based superalloy is used for piston seal, then creep resistance is improved, but wear resistance deteriorates due to chromia and alumina formation increasing friction
Solution Approach 1:
The patent applies a composite coating system consisting of multiple layers: a bond coat, an intermediate coat containing reactive elements (Al, Ti, Hf), and an outer protective coat. This composite structure combines materials with complementary properties to achieve both creep resistance from the nickel-based superalloy substrate and wear resistance from the engineered coating system, preventing the formation of high-friction chromia and alumina scales.
Solution Approach 2:
The patent modifies the chemical composition parameters of the coating layers, specifically controlling the content of reactive elements (Al: 3-15 wt%, Ti: 2-10 wt%, Hf: 1-5 wt%) in the intermediate coat and protective coat. By adjusting these compositional parameters, the coating system achieves optimal oxidation resistance and wear resistance while maintaining compatibility with the nickel-based superalloy substrate, preventing harmful scale formation.
2Power
If high temperature operation is maintained, then engine performance is improved, but friction and wear increase due to chromia and alumina formation on seal surface
Solution Approach 1:
The patent converts the harmful effect of high temperature oxidation into a beneficial protective mechanism. The intermediate coat containing reactive elements (Al, Ti, Hf) is designed to preferentially oxidize and form a stable, low-friction oxide barrier that protects the underlying nickel-based superalloy. This controlled oxidation approach transforms the harmful high-temperature environment into a condition that enhances rather than degrades seal performance.
Solution Approach 2:
The patent introduces an intermediate coat as a mediator between the nickel-based superalloy substrate and the external high-temperature environment. This intermediate layer, containing reactive elements, acts as a buffer that controls the interaction between the seal and the harsh operating conditions, preventing direct formation of high-friction chromia and alumina on the substrate while allowing the seal to operate at high temperatures for optimal engine performance.
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 ternary oxide coating provides excellent creep and wear resistance, reducing friction and extending the life of engine components by minimizing wear and thermal damage, thus enhancing operational efficiency and reducing maintenance costs.
Implementation Method 1
the ternary oxide contains a metal oxide that forms nanoparticles when subjected to sliding or vibratory motion
Implementation Method 2
the coating comprises a ternary oxide... that forms nanoparticles to act as a solid lubricant, reducing friction and wear
Data Source
AI summary
A seal assembly for a gas turbine engine includes a seal composed of a nickel-based superalloy; a component in contact with the seal and defining a seal-counterface; and a coating on the seal at the seal-counterface, wherein the coating is a ternary oxide.