Piston Ring Coating with Nickel Intermediate Layer for Seizure Prevention
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Solution Overview
Problem
Iron-based thermal spray coatings used in piston rings are prone to seizing and material fatigue due to adhesive wear with similar metal counterparts, and high carbide content deteriorates fatigue strength and fracture toughness, while existing powders are costly and inefficient.
Innovation Solution
A powder composition of 15-30% iron, 15-30% tungsten, 25-35% chromium, 10-35% nickel, 1-5% molybdenum, 0.2-3% aluminum, 3-20% copper, 1-10% carbon, and 0.1-2% silicon, with 20-50% carbides and 5-20% solid lubricants, applied via high-speed flame or plasma spraying, to create a quasi-homogeneous coating with improved wear resistance and fracture toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If iron-based thermal spray coatings are used in piston rings, then wear resistance is improved, but seizing and adhesive wear occur due to similar metal counterparts
Solution Approach 1:
A nickel-based intermediate layer is applied between the iron-based piston ring and the iron-based cylinder liner. This intermediate layer acts as a mediator that prevents direct contact and adhesive wear between similar iron surfaces, thereby reducing seizing while maintaining wear resistance of the iron-based coating.
Solution Approach 2:
The coating system uses a composite structure with an iron-based outer layer for wear resistance and a nickel-based intermediate layer for seizure prevention. This composite material approach combines the advantages of both materials to simultaneously achieve wear resistance and reliability.
2Reliability
If molybdenum-based powders are used to achieve desired properties, then performance requirements are met, but production costs increase significantly
Solution Approach 1:
The patent replaces expensive molybdenum-based powders with more cost-effective iron-based powders containing controlled amounts of carbides and solid lubricants. This substitution significantly reduces material costs while maintaining the required performance through optimized composition and the nickel intermediate layer.
Solution Approach 2:
The powder composition is optimized with specific ranges of iron, carbides, nickel, and solid lubricants to achieve the desired performance at lower cost. The controlled composition ensures adequate wear resistance, seizure prevention, and mechanical properties without requiring expensive molybdenum-based materials.
3Strength
If thermal spray coating is applied to improve wear protection, then sliding element protection is enhanced, but thermal energy dissipation and thermal relaxation are insufficient
Solution Approach 1:
The coating composition includes iron (15-30 wt%) and nickel (10-35 wt%) which provide good thermal conductivity. The controlled carbide content (20-50 wt% total) and solid lubricant additions optimize both wear protection and thermal properties, enabling better thermal energy dissipation and uniform thermal relaxation during engine operation.
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 new coating system enhances thermal energy dissipation, reduces burn and scuff resistance, and improves fatigue behavior, while being approximately 30% cheaper than current molybdenum-based powders, with a porosity of <2% and hardness in the range of 500-1000 HV0.1 μm, and fracture toughness of 2.5-7.5 (MPa m)1/2, effectively addressing the issues of seizing and material fatigue.
Implementation Method 1
The production of wear protection layers using the thermal spray process is a generally known process
Implementation Method 2
the thermal energy generated during mixed friction, especially in the area of top and bottom dead center (TDC/UT), can be better dissipated
Data Source
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Figure 3~4
AI summary
The invention relates to a method for producing a piston ring for an internal combustion engine, which comprises: providing a substrate; and applying a coating by means of thermal spraying of a powder, that includes solid lubricants, and comprises the elemental proportions 15-30 wt % of iron, Fe; 15-30 wt % of tungsten, W; 25-35 wt % of chromium, Cr; 10-35 wt % of nickel, Ni; 1-5 wt % of molybdenum, Mo; 0.2-3 wt % of aluminum, Al; 3-20 wt % of copper, Cu; 1-10 wt % of carbon, C; 0.1-2 wt % of sulfur, S; and 0.1-2 wt % of silicon, Si.