Sliding Bearing Layer Grain Gradient Against Interface Shear Failure
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Solution Overview
Problem
Conventional sliding members with a copper alloy sliding layer and steel back-metal layer are prone to shear failure due to differences in elastic deformation resistance at their interface, leading to inadequate bonding and increased risk of failure during operation.
Innovation Solution
A sliding member design featuring a back-metal layer with an Fe alloy and a copper alloy sliding layer containing 0.5 to 12% Sn, where the sliding layer has a cross-sectional structure with distinct grain sizes and compositions to enhance bonding, including interface grains with a smaller average grain size and non-interface grains with a larger size ratio, reducing shear failure likelihood.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a copper alloy sliding layer is used on a steel back-metal layer, then seizure resistance and wear resistance are achieved, but shear failure occurs at the interface between the sliding layer and back-metal layer under large external forces
Solution Approach 1:
The patent applies local quality by creating a gradient grain structure within the copper alloy sliding layer. The grain size varies from the bonding interface toward the sliding surface, with smaller grains (D1) at the interface region and larger grains (D2) in the bulk. This local variation in microstructure optimizes the interface region for bonding strength while maintaining the bulk properties for seizure and wear resistance, directly resolving the contradiction between interface bonding strength and overall reliability.
Solution Approach 2:
The patent employs parameter changes by controlling the grain size distribution in the copper alloy sliding layer. Specifically, it establishes that the average grain size at the bonding interface (D1) should be 30 to 80 μm, and the ratio D1/D2 should be 0.1 to 0.3. By changing the grain size parameter spatially within the sliding layer, the patent enhances interface bonding strength without compromising the seizure and wear resistance provided by the copper alloy composition.
2Force
If the sliding layer undergoes elastic deformation under large external forces, then the bearing can accommodate load, but shear failure occurs at the bonding interface
Solution Approach 1:
The patent applies local quality by creating a gradient grain structure within the copper alloy sliding layer. The grain size varies from the bonding interface toward the sliding surface, with smaller grains (D1) at the interface region and larger grains (D2) in the bulk. This local variation in microstructure optimizes the interface region for bonding strength while maintaining the bulk properties for seizure and wear resistance, directly resolving the contradiction between interface bonding strength and overall reliability.
Solution Approach 2:
The patent employs parameter changes by controlling the grain size distribution in the copper alloy sliding layer. Specifically, it establishes that the average grain size at the bonding interface (D1) should be 30 to 80 μm, and the ratio D1/D2 should be 0.1 to 0.3. By changing the grain size parameter spatially within the sliding layer, the patent enhances interface bonding strength without compromising the seizure and wear resistance provided by the copper alloy composition.
Data Source
Figure 1~2
Figure 3~4
AI summary
A sliding member (1) includes a back-metal layer (2) including an Fe alloy and a sliding layer (3) including a copper alloy (4) including 0.5 to 12 mass% of Sn and the balance of Cu and inevitable impurities. The sliding layer (3) has a cross-sectional structure perpendicular to a sliding surface (31) of the sliding layer. The cross-sectional structure includes first copper alloy grains (41) that are in contact with a bonding surface (21) of the back-metal layer (2) and second copper alloy grains (42) that are not in contact with the bonding surface (21). The first copper alloy grains (41) has an average grain size D1 and the second copper alloy grains (42) has an average grain size D2. D1 and D2 satisfy the following relations: D1 is 30 to 80 µm; and D1/D2 = 0.1 to 0.3.