Sliding Element With PTFE Gradient Layer
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Solution Overview
Problem
Thermoplastic-based sliding materials exhibit a significantly higher coefficient of friction when lubricated by media compared to PTFE-based materials, limiting their effectiveness in wear-intensive applications.
Innovation Solution
A sliding element with a metallic support layer and a porous metallic carrier layer, featuring a sliding layer with a thermoplastic matrix and a PTFE gradient that adjusts wear resistance and sliding properties by varying the PTFE content across the surface depth, optimized through a process of powder application, compaction, impregnation with a PTFE dispersion, and rolling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermoplastic materials are used as sliding layer, then wear resistance is improved, but coefficient of friction increases significantly when lubricated by media
Solution Approach 1:
The patent applies a gradient structure where PTFE concentration varies through the thickness of the sliding layer. The surface region contains higher PTFE concentration to reduce friction, while deeper layers have lower PTFE concentration to maintain wear resistance. This local variation in material composition resolves the contradiction between low friction and high wear resistance.
Solution Approach 2:
The sliding layer is constructed as a composite material combining thermoplastic matrix with PTFE dispersion. This composite structure allows the material to exhibit both the wear resistance of thermoplastics and the low friction properties of PTFE, resolving the contradiction between these two opposing requirements.
2Object-affected harmful factors
If PTFE content is increased to reduce friction, then coefficient of friction decreases, but wear resistance deteriorates due to matrix weakening
Solution Approach 1:
The gradient structure distributes PTFE concentration non-uniformly through the sliding layer thickness. The surface region has high PTFE concentration for low friction, while the bulk material maintains sufficient thermoplastic content for wear resistance. This spatial distribution resolves the contradiction between friction reduction and wear resistance.
Solution Approach 2:
The patent changes the concentration parameter of PTFE as a function of depth through the sliding layer. By controlling the PTFE dispersion concentration gradient, the material achieves optimal balance between friction and wear properties at different depths, resolving the contradiction between these two parameters.
3Object-affected harmful factors
If uniform PTFE distribution is used throughout the sliding layer, then friction properties are improved, but wear resistance is compromised due to matrix weakening
Solution Approach 1:
Instead of uniform distribution, the patent implements a gradient distribution where PTFE concentration varies with depth. The surface has high PTFE for low friction, while deeper layers have reduced PTFE to maintain matrix strength and wear resistance, resolving the contradiction between friction and wear properties.
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
Significantly improves the coefficient of friction and wear resistance of thermoplastic-based sliding elements, ensuring effective performance throughout their service life by balancing PTFE content and pore structure, making them suitable for media-lubricated applications like shock absorbers and pumps.
Implementation Method 1
a porous metallic carrier layer applied thereon... impregnating the compacted first material with a dispersion of a second material containing PTFE
Implementation Method 2
melting the sliding layer and rolling the sliding layer
Data Source
Figure 1a~2
AI summary
The invention relates to a sliding element comprising a metallic support layer (2), a metallic porous carrier layer (3) applied thereon and a sliding layer which has the thickness D and is applied on the carrier layer, said sliding layer comprising at least one thermoplast as matrix material. The layer (6) comprises a first material (4) containing the thermoplast matrix and a second material (5) containing PTFE, which forms a gradient over a depth T ≤ D in a surface region of the first material.