Copper Alloy Sliding Layer Structure for Stronger Interface Bonding
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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 on the sliding surface.
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 areas, 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 and 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 at the interface with the back-metal layer under large external forces
Solution Approach 1:
The patent applies local quality by creating a gradient structure in the sliding layer where grain size varies through the thickness. The first copper alloy grains near the bonding surface have a different average grain size (D1) than the second copper alloy grains in the sliding body (D2), with D1/D2 satisfying 0.05 ≤ D1/D2 < 0.50. This gradient grain structure optimizes both bonding strength at the interface and overall reliability of the sliding layer.
2Adaptability or versatility
If the sliding layer undergoes elastic deformation under large external forces, then the sliding member can accommodate the force, but the elastic deformation causes shear failure at the interface or cracks on the sliding surface
Solution Approach 1:
The patent applies parameter changes by controlling the grain size parameter throughout the sliding layer thickness. By setting the ratio of average grain sizes D1/D2 within 0.05 ≤ D1/D2 < 0.50, the material properties are optimized to balance elastic deformation capability with resistance to shear failure and cracking, allowing the sliding layer to accommodate external forces without failing.
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 surface cracking, ensuring stronger bonding between the sliding and back-metal layers, even under high external forces, by controlling grain size and structure to balance deformation resistance and ductility.
Implementation Method 1
solidifying the copper alloy unidirectionally by cooling the substrate from the second surface by a coolant
Implementation Method 2
casting the molten copper alloy on the first surface of the substrate
Data Source
Figure 1~3
Figure 4~5
AI summary
A sliding member (1) includes a back-metal layer (2) 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. A cross-sectional structure of the sliding layer includes first copper alloy grains (41) in contact with a bonding surface (21) and second copper alloy grains (42) not in contact with the bonding surface (21). 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 (43) that includes internal grains (44) therein that are not in contact with a grain boundary of the third grains. A total area S I of the third grains and a total area of the second copper alloy grains S2 satisfy: S0/S2 = 0.25 to 0.80.