Boron-Laminated Piston Ring Coating for Wear Resistance
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Solution Overview
Problem
Existing piston ring technologies face challenges in maintaining wear resistance due to complex film formation processes and inadequate adhesion of amorphous hard carbon layers, leading to inconsistent wear resistance performance.
Innovation Solution
A piston ring with a laminated hard carbon film containing boron within a specific atomic density range, formed using an arc ion plating method, which enhances wear resistance by improving adhesion and reducing surface unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layered structure with different hardness layers is formed by sputtering and ion plating, then wear resistance is improved, but the film formation process becomes complex
Solution Approach 1:
The patent combines sputtering and ion plating processes into a single integrated film formation step, where a carbon-based coating is deposited while simultaneously applying both sputtering and ion plating. This merging of processes simplifies the overall manufacturing while maintaining the wear resistance benefits of multi-layered structures.
Solution Approach 2:
The invention uses a composite carbon-based coating material that inherently possesses both hard and soft phases within a single layer structure. This composite material approach eliminates the need for separate hard and soft layers, simplifying the film formation process while maintaining excellent wear resistance through the intrinsic properties of the composite coating.
2Ease of manufacture
If the high hardness layer thickness is reduced to 5 nm to 90 nm, then the coating becomes easier to form, but wear resistance cannot be maintained
Solution Approach 1:
The patent changes the deposition parameters by simultaneously applying sputtering and ion plating during coating formation. This parameter change allows for optimal control of film density and structure, enabling the formation of sufficiently thick wear-resistant layers while maintaining ease of manufacture through a single integrated process.
3Strength
If amorphous hard carbon layers are applied, then adhesion to base material is improved, but the layers lack sufficient hardness and wear resistance
Solution Approach 1:
The patent employs a composite carbon-based coating containing both hard and soft phases. The soft phase ensures excellent adhesion to the base material, while the hard phase provides sufficient hardness and wear resistance. This composite structure resolves the contradiction between adhesion and mechanical properties.
Solution Approach 2:
The coating structure is designed with local quality variations, where soft regions provide adhesion to the base material and hard regions provide wear resistance. This spatial distribution of different properties within the single coating layer allows simultaneous achievement of good adhesion and high hardness.
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 piston ring exhibits excellent wear resistance and ease of formation, with a surface hardness range of 10 GPa to 25 GPa, and a total film thickness of 0.5 µm to 20 µm, effectively addressing the limitations of previous technologies.
Implementation Method 1
formed using an arc ion plating method
Implementation Method 2
formed using an arc ion plating method
Data Source
Figure 1A~1B
Figure 2~3
Figure 4A~4B
AI summary
To provide a piston ring comprising a hard carbon film that is easy to form and exhibits excellent wear resistance. The above-described problem is solved by having a hard carbon film 4 formed on at least an outer peripheral sliding surface 11 of a piston ring base material 1, wherein the hard carbon film 4 is a laminated film comprising a plurality of layers, and is configured so as to contain boron within a range of an atomic density of 0.2 x 1022 atoms/cm3 to 2.0 x 1022 atoms/cm3 inclusive. This hard carbon film 4 may be configured to have an sp2 component ratio within a range of 40% to 80% inclusive, measured in a TEM-EELS spectrum formed by combining electron energy loss spectroscopy (EELS) with a transmission electron microscope (TEM), and a hydrogen content within a range of 0.1 atom% to 5 atom% inclusive. Further, a total thickness of this hard carbon film 4 may be configured to be within a range of 0.5 µm to 20 µm inclusive.