Piston Ring Wear-Prevention Layer and Corrosion-Resistant Flank Surface
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Solution Overview
Problem
Piston rings in internal combustion engines face high thermal stress and corrosion due to their position near the combustion chamber, leading to increased wear and corrosion on the flank surfaces, despite hardening processes like nitriding, which compromise corrosion resistance.
Innovation Solution
A piston ring design featuring a chromium steel base body with a nitride diffusion layer, a nitride connecting layer, and an oxide layer on the flank surfaces, and a chromium solid particle layer on the outer circumferential surface, produced through a combined nitriding-oxidation process and electrochemical deposition, enhancing both wear resistance and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a nitride diffusion layer is applied to harden the flank surfaces, then wear resistance increases, but corrosion resistance deteriorates
Solution Approach 1:
The flank surface is segmented into multiple functional layers: a nitride diffusion layer for wear resistance, a nitride connecting layer for adhesion, and an oxide layer for corrosion protection. Each layer performs its specific function without interfering with the others, resolving the contradiction between wear resistance and corrosion resistance.
Solution Approach 2:
The piston ring flank surface uses a composite structure combining different materials and properties: chromium steel base body, nitride diffusion layer (hard, wear-resistant), nitride connecting layer (adhesive), and oxide layer (corrosion-resistant). This composite approach allows simultaneous achievement of wear resistance and corrosion resistance.
2Strength
If hard chromium coating is applied to the outer circumferential surface, then wear resistance improves, but the multi-layer complexity increases
Solution Approach 1:
Different surface treatments are applied to different locations of the piston ring: the outer circumferential surface receives a chromium solid particle layer for wear resistance, while the flank surfaces receive the nitride-oxide multi-layer structure. This localized approach optimizes each surface for its specific functional requirements without unnecessarily complicating the entire structure.
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 multi-layer structure provides high hardness and corrosion resistance on the flank surfaces while maintaining low friction and wear on the outer circumferential surface, suitable for high-pressure diesel engine applications.
Implementation Method 1
a nitride diffusion layer with a layer thickness of from 5-300 μm
Implementation Method 2
an oxide layer arranged directly above this with a layer thickness of from 0.05-3 μm
Implementation Method 3
a chromium solid particle layer is deposited electrochemically onto at least the outer circumferential surface
Data Source
AI summary
A coated piston ring having a base body of chromium steel with more than 10 wt.-% chromium and having an inner circumferential surface, a first flank surface, a second flank surface and an outer circumferential surface. The first flank surface comprises a nitride diffusion layer with a layer thickness of from 5-300 μm, a nitride connecting layer with a layer thickness of from 0.5-15 μm on the nitride diffusion layer, and an oxide layer with a layer thickness of from 0.05-3 μm on the nitride connecting layer. The second flank surface comprises the nitride diffusion layer, and the outer circumferential surface comprises the nitride diffusion layer and a chromium solid particle layer with 0.1-30 vol.-% solid particles, relative to the total volume of the chromium solid particle layer on the nitride diffusion layer.