Piston Ring Alloy Coating for Low Friction and Crack Resistance
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Solution Overview
Problem
Current sliding members, such as piston rings for internal combustion engines, face challenges in achieving adequate wear resistance and toughness, especially under severe conditions associated with weight saving and increased output, and are susceptible to cracking and peeling when used in alcohol fuel vehicles.
Innovation Solution
A sliding member with a Cr—B—Ti—V—(Mn, Mo)—N-based alloy film is developed, where the alloy film contains Mn and Mo in a total content of 2 mass % or less, with B, V, and Ti within specific ranges, and a nitriding treatment layer or metal underlayer is used to enhance toughness and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard film (chromium plating, nitrided layer, PVD film) is formed on the outer peripheral sliding surface to improve wear resistance, then wear resistance is improved, but the film is susceptible to cracking and peeling under severe conditions (high temperature, high pressure, alcohol fuel environment)
Solution Approach 1:
The patent changes the chemical composition parameters of the wear-resistant film by incorporating specific elements (Ti: 1-5 mass%, V: 0.1-1 mass%, B: 0.05-0.5 mass%, Mn: 0.1-1 mass%, Mo: 0.1-1 mass%) into the chromium-based alloy system. This compositional adjustment modifies the film's microstructure and mechanical properties, enhancing both wear resistance and toughness to prevent cracking and peeling under severe operating conditions including alcohol fuel environments
Solution Approach 2:
The patent creates a composite alloy film system (Cr-B-Ti-V-(Mn,Mo)-N) that combines multiple metallic elements with complementary properties. Chromium provides base hardness and wear resistance, while titanium and vanadium enhance strength and toughness, boron refines grain structure, and manganese/molybdenum further improve mechanical properties. This multi-element composite structure achieves synergistic effects that simultaneously improve wear resistance and resistance to cracking/peeling
2Productivity
If the piston ring is designed for weight saving and increased output, then engine performance is improved, but the sliding member is used under more severe conditions requiring higher toughness and wear resistance
Solution Approach 1:
The patent adjusts the chemical composition parameters of the coating film to achieve optimal mechanical properties under severe operating conditions. By precisely controlling the content ranges of alloying elements (Ti: 1-5 mass%, V: 0.1-1 mass%, B: 0.05-0.5 mass%, Mn: 0.1-1 mass%, Mo: 0.1-1 mass%), the film achieves enhanced toughness and wear resistance necessary for high-performance engines operating under weight-saving constraints
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 provides a sliding member with low friction and excellent toughness, reducing the likelihood of adhesion, cracking, and peeling, and is applicable under severe conditions, including those involving alcohol fuels, while maintaining wear resistance and peeling resistance.
Implementation Method 1
a hard film formed by a physical vapor deposition (PVD) method
Implementation Method 2
the outer peripheral surface of the piston ring is coated with a hard film by arc ion plating
Implementation Method 3
a nitrided layer
Data Source
AI summary
To provide a sliding member, such as a piston ring for an internal combustion engine, having low friction and excellent toughness. The above-described problem is solved by a sliding member (10) such as a piston ring coated with a Cr—B—Ti—V—(Mn, Mo)—N-based alloy film (2) on a sliding surface (11) thereof, and configured so that the alloy film (2) contains one or both of Mn and Mo and has a total content of the Mn and the Mo within a range of 2 mass % or less. Preferably, a B content is within a range of 0.1 mass % to 1.5 mass %, inclusive, a V content is within a range of 0.05 mass % to 1 mass %, inclusive, and a Ti content is within a range of 0.05 mass % to 1.5 mass %, inclusive.