Plain Bearing Composite Material Fatigue Resistance
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Solution Overview
Problem
Existing plain bearing composite materials face issues with mechanical stability and load-bearing capacity, particularly under heavy loads, and are prone to axial displacement and fatigue due to severe hardening and embrittlement from high copper content, and roll-bonding processes do not effectively address these challenges in modern automotive applications.
Innovation Solution
A method involving a bearing metal layer with a moderate hardness achieved through soft annealing between 280° and 350°C, combined with a thin, galvanically or PVD-applied overlay, and optional intermediate layers to enhance resilience and prevent axial crushing, using an aluminum-based alloy with controlled magnesium content and a PVD overlay composition for improved tribological properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bearing metal layer is severely hardened by alloying large amounts of copper to increase load-bearing capacity, then the hardness and load-bearing capacity are improved, but the material becomes embrittled which impairs fatigue strength and leads to axial displacement under heavy loads
Solution Approach 1:
The patent changes the chemical composition parameters by limiting copper content to 3.5-4.5% by weight and magnesium content to 0.1-1.5% by weight, and modifies the heat treatment parameters by using solution annealing at high temperatures followed by quenching instead of severe hardening treatments. This parameter optimization achieves the desired load-bearing capacity while preventing embrittlement and maintaining fatigue strength.
2Strength
If the bearing metal layer is severely hardened to prevent axial displacement under heavy loads, then the load-bearing capacity is improved, but the material becomes more sensitive to dirt particles in the oil flow
Solution Approach 1:
The patent optimizes the hardness parameter by controlling the alloy composition and heat treatment process to achieve a balanced hardness level that provides sufficient resistance to axial displacement while maintaining low sensitivity to dirt particles. The specific composition range and solution annealing treatment create an optimal hardness profile that satisfies both requirements.
3Ease of manufacture
If roll-bonding is used to apply the bearing metal layer and overlay, then the manufacturing process is established, but the composite material does not achieve sufficient mechanical stability and permanent load-bearing capacity for modern automotive applications
Solution Approach 1:
The patent creates a composite material structure with a steel support layer, an aluminum-based bearing metal layer with optimized composition, and a metallic overlay. The specific composition ranges and heat treatment process create a composite structure that achieves superior mechanical stability and permanent load-bearing capacity while remaining compatible with roll-bonding manufacturing processes.
4Reliability
If a thick overlay is applied to the bearing metal layer to improve sliding properties, then the tribological performance is enhanced, but the fatigue resistance and resistance to seizure are reduced
Solution Approach 1:
The patent applies a thin metallic overlay with thickness of at most 30 μm, in particular at most 25 μm, in particular at most 20 μm, and at least 5 μm, in particular at least 10 μm, in particular 10-20 μm, to the bearing metal layer. This localized thin coating provides the necessary tribological performance while maintaining the fatigue resistance of the underlying bearing metal layer, avoiding the problems associated with thick overlays.
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 method results in a plain bearing composite material with enhanced load-bearing capacity, resistance to fatigue and seizure, and reduced sensitivity to dirt particles, ensuring stability and longevity under high loads, suitable for modern automotive applications like crankshaft and connecting rod bearing shells.
Implementation Method 1
A hardenable aluminum-based alloy with a comparatively high copper content of 3.5 to 4.5% by weight of copper and with 0.1 to 1.5% by weight of magnesium to use in order to achieve a preferred hardness of 70 to 110 HV 0.01 (Vickers hardness). This can be achieved due to the high copper content and presumably by solution annealing at high temperatures and subsequent quenching.
Implementation Method 2
the composite thus obtained is soft annealed at temperatures between 280° and 350°C, in particular between 300° and 350°C. Comparatively large precipitates are formed here, typically in the range of 1 - 10 μm, and only moderate hardness is achieved in the stressed area.
Implementation Method 3
a thin sliding layer is applied to the bearing metal layer by electroplating or by a PVD process
Implementation Method 4
a thin sliding layer is applied to the bearing metal layer by electroplating or by a PVD process
Data Source
Figure 1~3
Figure 4
AI summary
The invention relates to a method for producing a sliding bearing composite material (10) with a support layer (14), in particular made of steel, with a bearing metal layer (18) made of a lead-free, magnesium-comprising aluminum-based alloy and with a running layer (22), wherein the aluminum-based alloy ultimately comprises 0.5 - 5.5 wt.% magnesium, optionally one or more alloying components from the group consisting of zinc, copper, silicon, iron, manganese, chromium, titanium, zirconium, vanadium, nickel, cobalt, cerium and impurity-related alloying components, the latter not exceeding a total of 1 wt.%, and the remainder being aluminum, wherein the aluminum-based alloy is copper-free or comprises at most 3 wt.% copper, and wherein the total content of zinc, copper and nickel does not exceed 8 wt.% and the total content of all alloying components does not exceed 12 wt.%.-% not exceeding, wherein the bearing metal layer (18) is either rolled directly onto the support layer (14) or is first roll-clad with an intermediate layer (38) of an aluminum alloy or of technical grade pure aluminum and then rolled onto the support layer (14) with intermediate layer (38) such that the intermediate layer (38) is afterwards at most 100 µm thick, in particular at most 50 µm thick, wherein the composite of support layer (14) and bearing metal layer (18) thus obtained is annealed at temperatures between 280°-350° Celsius for 2 to 10 hours, so that the bearing metal layer of the composite has a Brinell hardness of 50-80 HB 1/5/30, and wherein the running layer (22) is then applied to the bearing metal layer (18) by electroplating or by a PVD process.