Copper Alloy Sliding Layer Grain Structure for Shear-Resistant Bonding
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Solution Overview
Problem
Conventional sliding members with a copper alloy sliding layer and a steel back-metal layer are prone to shear failure due to differences in elastic deformation resistance at the interface, leading to weak bonding and potential 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 conventional sliding member with a copper alloy sliding layer on a steel back-metal layer is used, then the sliding layer achieves seizure resistance and wear resistance, but the sliding member is prone to shear failure 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 in grain size within the copper alloy sliding layer. The grain size varies from smaller at the bonding interface with the back-metal layer to larger toward the sliding surface. This local variation in microstructure optimizes the interface region for bonding strength while maintaining overall sliding properties, directly addressing the shear failure problem at the interface.
Solution Approach 2:
The patent changes the microstructural parameter of grain size within the sliding layer. By controlling the grain size distribution (smaller grains at the interface, larger grains at the surface) through specific casting and cooling conditions, the material properties are optimized to prevent shear failure while maintaining sliding performance.
2Reliability
If the sliding layer is made of copper alloy with Sn content of 0.5 to 12 mass%, then the bonding between sliding layer and back-metal layer is improved, but the manufacturing precision of grain size control becomes more challenging
Solution Approach 1:
The patent specifies precise compositional parameters (Sn content of 0.5 to 12 mass%) and microstructural parameters (grain size ratio D1/D2 of 0.1 to 0.3) to achieve optimal bonding. These parameter ranges are determined to balance bonding improvement with manufacturability, providing clear guidance for production while ensuring reliable interface bonding.
Data Source
AI summary
A sliding member includes a back-metal layer including an Fe alloy and a sliding layer including a copper alloy including 0.5 to 12 mass % of Sn and the balance of Cu and inevitable impurities. The sliding layer has a cross-sectional structure perpendicular to a sliding surface of the sliding layer. The cross-sectional structure includes first copper alloy grains that are in contact with a bonding surface of the back-metal layer and second copper alloy grains that are not in contact with the bonding surface. The first copper alloy grains has an average grain size D1 and the second copper alloy grains 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.