Hard Carbon Piston Ring Coating for Wear and Peeling Resistance
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Solution Overview
Problem
Existing sliding members with diamond-like carbon (DLC) coatings face challenges in achieving both high peeling resistance and high wear resistance, particularly as the coating thickness increases beyond 3 µm, where focusing solely on Young's modulus and indentation hardness is insufficient.
Innovation Solution
A hard carbon coating with a thickness of 3 µm or more, formed by ion plating with a hydrogen content of 3 atomic % or less, where the ratio of Martens hardness to indentation hardness is 0.40 or more, and applied with a bias voltage of -50 V to 0 V and a discharge current of 50 A to 200 A, enhancing peeling and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the coating thickness is increased to 3 µm or more for improved durability, then wear resistance improves, but peeling resistance deteriorates due to insufficient consideration of elastic deformation
Solution Approach 1:
The invention changes the parameter focus from solely indentation hardness to include both Martens hardness and indentation hardness with a specific ratio (HM/HIT ≥ 0.40). This parameter change allows the coating to maintain high durability through increased thickness while preventing peeling by ensuring adequate elastic deformation capability through the Martens hardness component.
Solution Approach 2:
The invention creates a composite performance profile by combining two hardness measurements (Martens hardness and indentation hardness) in a specific ratio. This composite approach to characterizing the DLC coating enables simultaneous optimization of both peeling resistance and wear resistance, resolving the contradiction between thickness-induced durability improvement and peeling resistance deterioration.
2Strength
If the Young's modulus is increased to improve hardness, then wear resistance improves, but the coating becomes prone to cracking and peeling
Solution Approach 1:
The invention transitions from focusing solely on Young's modulus and indentation hardness to a dual-parameter system incorporating both Martens hardness (HM) and indentation hardness (HIT) with HM/HIT ≥ 0.40. This parameter change enables the coating to achieve high hardness for wear resistance while maintaining sufficient elasticity to prevent cracking and peeling.
3Strength
If the indentation hardness is increased to improve wear resistance, then plastic deformation resistance improves, but elastic deformation capability deteriorates
Solution Approach 1:
The invention introduces a ratio-based parameter system where Martens hardness (representing elastic deformation capability) divided by indentation hardness (representing plastic deformation resistance) must be 0.40 or more. This parameter change ensures that wear resistance is maintained through adequate indentation hardness while elastic deformation capability is preserved through sufficient Martens 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 solution achieves a sliding member with improved peeling and wear resistance, balancing Martens hardness for elastic deformation and indentation hardness for plastic deformation, preventing brittleness and ensuring durability.
Implementation Method 1
a hard carbon coating that is formed on the base member and has a hydrogen content of 3 atomic % or less and a thickness of 3 µm or more; wherein the hard carbon coating is formed by an ion plating process
Data Source
Figure 1~2
Figure 3
AI summary
A sliding member having a hard carbon coating that has a thickness of 3 µm or more and demonstrates high peeling resistance and high wear resistance is provided. A sliding member 100 according to the present disclosure includes a base member 10 and a hard carbon coating 12 that is formed on the base member 10 and has the hydrogen content of 3 atomic % or less and a thickness of 3 µm or more. When HM represents a Martens hardness of the hard carbon coating 12 and HIT represents an indentation hardness, the ratio HM/HIT is 0.40 or more.