Copper Alloy Sliding Layer Structure Against Interface Shear Cracking
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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 and cracking due to elastic deformation differences at the interface, leading to reduced bonding strength and increased damage during operation in internal combustion engines and automatic transmissions.
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, including columnar crystals and internal-crystal-inclusive grains, to enhance bonding and reduce shear failure, achieved through a centrifugal casting process.
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 provides seizure resistance and wear resistance, but the sliding layer is prone to shear failure and cracking at the interface with the back-metal layer due to elastic deformation differences
Solution Approach 1:
The invention applies local quality by creating a gradient in grain size within the sliding layer. The grain size transitions from smaller grains at the interface with the back-metal layer to larger grains toward the sliding surface. This local variation in microstructure allows the interface region to better accommodate elastic deformation differences, preventing shear failure while maintaining the overall functionality of the sliding layer.
Solution Approach 2:
The invention changes the physical parameter of grain size distribution within the sliding layer. By controlling the average grain size at the interface to be 10-30 μm and the average grain size toward the surface to be 50-200 μm, the patent creates a controlled parameter gradient that resolves the contradiction between bonding strength and resistance to shear failure.
2Reliability
If the sliding layer has a uniform grain structure, then the manufacturing process is simpler, but the bonding strength at the interface is insufficient under dynamic friction conditions
Solution Approach 1:
The invention applies local quality by creating a gradient in grain size within the sliding layer. The grain size transitions from smaller grains at the interface with the back-metal layer to larger grains toward the sliding surface. This local variation in microstructure allows the interface region to better accommodate elastic deformation differences, preventing shear failure while maintaining the overall functionality of the sliding layer.
Solution Approach 2:
The invention changes the physical parameter of grain size distribution within the sliding layer. By controlling the average grain size at the interface to be 10-30 μm and the average grain size toward the surface to be 50-200 μm, the patent creates a controlled parameter gradient that resolves the contradiction between bonding strength and resistance to shear failure.
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 design significantly reduces shear failure and cracking, ensuring stronger bonding between the sliding layer and back-metal layer, thereby improving the durability and performance of the sliding member under dynamic friction conditions.
Implementation Method 1
achieved through a centrifugal casting process
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. A cross-sectional structure of the sliding layer includes first copper alloy grains in contact with a bonding surface and second copper alloy grains not in contact with the bonding surface. The first and second grains have an average grain size D1 and D2 respectively. D1 is 30 to 80 μm; and D1/D2=0.1 to 0.3. In the cross-sectional structure, the second grains includes third grains that includes internal grains therein that are not in contact with a grain boundary of the third grains. A total area S1 of the third grains and a total area of the second copper alloy grains S2 satisfy: S0/S2=0.25 to 0.80.