Piston Ring Thermal Spray Coating Seizure Resistance
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Solution Overview
Problem
Thermal spray coatings for piston rings offer superior seizure resistance but are brittle and difficult to work with, making them impractical for use in internal combustion engines, while multi-layer chrome plating provides better workability but is prone to seizures.
Innovation Solution
A thermal spray coating with tungsten carbide and chrome carbide as hard phases and nickel as a metallic binder, where the mean particle diameter of tungsten carbide is adjusted between 0.15 μm and 0.45 μm, and nickel content is between 7.0 wt % and 18.5 wt %, formed using a granulation sintering method and applied with a high-speed frame spraying method, to balance seizure resistance and workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal spray coating is used as protective coating, then seizure resistance is improved, but workability deteriorates due to brittleness and crack occurrence
Solution Approach 1:
The patent applies parameter changes by precisely controlling the mean particle diameter of tungsten carbide within 0.15-0.45 μm and nickel content within 7.0-18.5 wt%. This optimization of physical and chemical parameters resolves the contradiction by creating a coating structure that balances hardness for seizure resistance with sufficient ductility for workability, preventing excessive brittleness while maintaining protective properties
Solution Approach 2:
The patent uses composite materials by combining tungsten carbide hard particles with nickel binder phase to create a cermet thermal spray coating. This composite structure allows the hard WC particles to provide seizure resistance while the ductile nickel matrix provides workability and crack tolerance, effectively resolving the contradiction between these two opposing requirements
2Ease of manufacture
If multi-layer chrome plating is used as protective coating, then workability is improved, but seizure resistance deteriorates due to uniform coating structure
Solution Approach 1:
The patent replaces uniform chrome plating with a composite thermal spray coating containing tungsten carbide hard particles distributed in a nickel binder matrix. This composite structure creates microscopic heterogeneity that allows controlled drop-off of seizure portions while maintaining overall coating integrity, thereby improving seizure resistance while preserving workability
3Reliability
If thermal spray coating with hard particles is used, then seizure resistance is improved, but manufacturing precision deteriorates due to difficulty in application
Solution Approach 1:
The patent applies parameter changes by optimizing the mean particle diameter of tungsten carbide to 0.15-0.45 μm and nickel content to 7.0-18.5 wt%. These controlled parameters ensure proper coating formation during thermal spray application, achieving both seizure resistance and manufacturing precision by preventing excessive brittleness while maintaining protective properties
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 resulting piston ring coating exhibits superior seizure resistance compared to multi-layer chrome plating and equivalent or better workability, with low porosity and precise dimensions, enhancing its practical application in internal combustion engines.
Implementation Method 1
a piston ring that is provided with a thermal spray coating that contains tungsten carbide and chrome carbide as a hard phase, and contains nickel as a metallic binder phase, and in which the thermal spray coating is formed by the spraying of a thermal spray powder
Implementation Method 2
the thermal spray coating is formed by the spraying of a thermal spray powder that has been produced by means of a granulation sintering method
Data Source
AI summary
A piston ring is provided with a thermal spray coating that contains tungsten carbide and chrome carbide as a hard phase, and contains nickel as a metallic binder phase, and is characterized in that the thermal spray coating is formed by the spraying of a thermal spray powder that has been produced by means of a granulation sintering method, and that contains hard particles in which the mean particle diameter of the tungsten carbide has been adjusted by means of a BET method to fall within a range of not less than 0.15 μm and not more than 0.45 μm.