Tin-Based Sliding Layer with Preferred Beta-Tin Orientation
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Solution Overview
Problem
Existing sliding layers for multi-layer plain bearings often contain lead, which is environmentally problematic, and there is a need for sliding layers with improved tribological properties and fatigue strength while minimizing lead content.
Innovation Solution
A sliding layer made of a tin-based alloy with a specific composition, including antimony and copper, where beta-tin grains exhibit preferred orientation, enhancing wear resistance and fatigue strength, and potentially incorporating elements like zirconium or silicon for improved hardness, and an intermediate layer with higher hardness for better structural support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead is used in sliding layers, then tribological properties and fatigue strength are improved, but environmental compatibility deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by strictly limiting lead content to a maximum of 0.1% by weight (effectively creating a lead-free alloy) while optimizing other alloying elements such as antimony (2-20% wt), copper (3-10% wt), and bismuth (0.1-1.5% wt) to maintain or improve tribological properties and fatigue strength without lead
Solution Approach 2:
The patent creates a composite tin-based alloy system combining multiple elements (Sn-Sb-Cu-Pb-Bi) where each element contributes specific properties: antimony provides hardness and wear resistance, copper enhances ductility and fatigue strength, and bismuth improves embeddability, collectively replacing lead's functions in an environmentally compatible manner
2Strength
If copper content is increased in sliding layer, then fatigue strength is improved, but tribological properties deteriorate
Solution Approach 1:
The patent optimizes the copper content within a specific range (3-10% by weight) and balances it with antimony (2-20% wt) and bismuth (0.1-1.5% wt) content to achieve the optimal compromise between fatigue strength and tribological properties, preventing excessive copper from degrading surface performance while maintaining sufficient copper for fatigue resistance
Solution Approach 2:
The patent creates a multi-element composite alloy where copper works synergistically with antimony and bismuth: copper provides the matrix ductility and fatigue strength, while antimony and bismuth contribute to wear resistance and embeddability, collectively achieving both improved fatigue strength and maintained tribological properties
3Reliability
If antimony content is increased in sliding layer, then wear resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies a controlled antimony content range (2-20% by weight) that provides sufficient wear resistance while remaining within practical manufacturing limits for galvanic deposition processes, avoiding excessive antimony that would cause deposition difficulties and manufacturing complexity
Solution Approach 2:
The patent creates a balanced composite alloy where antimony is combined with copper and bismuth in specific proportions, allowing the alloy to achieve wear resistance through the antimony-copper-bismuth interaction rather than relying solely on high antimony content, thus maintaining manufacturability
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 results in sliding layers with improved wear resistance and fatigue strength, achieving better tribological properties while maintaining a low lead content, thus addressing environmental concerns and performance gaps in prior art.
Implementation Method 1
the beta-tin grains in the tin-based alloy have at least one preferred orientation
Implementation Method 2
improved tribological properties and/or a significantly higher fatigue strength
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a sliding layer (4) for a multi-layer sliding bearing (1) made of a tin-based alloy which, in addition to tin as the main alloying element, contains at least one element from the group consisting of antimony and copper, optionally lead and/or bismuth, as well as unavoidable impurities originating from the manufacture of the elements, wherein the antimony content is a maximum of 20 wt.%, the copper content a maximum of 10 wt.%, the total content of lead and bismuth a maximum of 1.5 wt.%, and the total content of copper and antimony is between 2 wt.% and 22 wt.%.-%, and wherein tin is present in the form of intermetallic phases and as a tin phase with beta-tin grains, and wherein the beta-tin grains in the tin-based alloy have at least one preferred orientation, wherein an orientation index M{hkl} according to the formula Mhkl=Ihkl∑I0hklI0hkl∑Ihkl of at least one lattice plane set M{hkl} has the value 3.0 or exceeds 3.0, where I{hkl} represents the X-ray diffraction intensities for the {hkl} planes of the sliding layer and 10{hkl} represents the X-ray diffraction intensities of the completely unoriented tin powder sample.