Sliding Member with Discontinuous Grain Boundary
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Solution Overview
Problem
Fatigue fractures in sliding bearings often transmit from a soft overlay layer to the base layer due to continuous grain boundaries, leading to premature failure and diffusion of alloy components.
Innovation Solution
A sliding member design featuring a base layer with soft particles and a soft layer, where the boundary between the two layers has a unique crystal grain structure, preventing intergranular fractures and diffusion by forming a discontinuous grain boundary and using anodic oxidation to control crystal growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a soft overlay layer is formed on the base layer to improve conformability and reduce friction, then the sliding performance is improved, but fatigue fractures transmit from the overlay layer to the base layer along continuous grain boundaries
Solution Approach 1:
The patent segments the continuous grain boundary structure by creating a barrier layer with different crystal grain structure between the base layer and overlay layer. This segmentation interrupts the continuous path for fatigue fracture propagation, preventing cracks from transmitting from the soft overlay layer to the hard base layer while maintaining the conformability benefits of the soft overlay.
Solution Approach 2:
The patent introduces a barrier layer as an intermediary between the base layer and overlay layer. This intermediate layer with unique crystal grain structure acts as a mediator that blocks the transmission of fatigue fractures while allowing the soft overlay to maintain good contact and conformability with the mating surface.
2Device complexity
If the overlay layer is directly plated on the base layer to simplify the structure, then the manufacturing process is simplified, but alloy components diffuse from the overlay layer to the base layer
Solution Approach 1:
The barrier layer serves as an intermediary that prevents direct contact and diffusion between the base layer and overlay layer. This intermediate structure blocks the diffusion path for alloy components while adding minimal structural complexity, as the barrier layer can be integrated into the existing plating process.
Solution Approach 2:
The patent creates a composite multi-layer structure where each layer has distinct properties. The barrier layer with unique crystal grain structure forms a composite material system that combines the benefits of the soft overlay for conformability with the protection of the base layer from diffusion, achieving both compositional stability and functional performance.
3Manufacturing precision
If an anodic oxidation film is formed on the soft particles before plating to control crystal growth, then epitaxial growth is prevented and grain boundary discontinuity is achieved, but the manufacturing process becomes more complex
Solution Approach 1:
The anodic oxidation treatment is performed as a preliminary action before the plating process. By pre-treating the soft particles with anodic oxidation to form a film on their surface, the patent controls the subsequent crystal grain growth during plating, ensuring the barrier layer develops the desired unique crystal grain structure that interrupts fatigue fracture paths.
Solution Approach 2:
The patent changes the surface parameters of the soft particles through anodic oxidation, modifying their surface properties to control crystal grain growth during plating. This parameter change creates a barrier layer with different crystal grain structure, achieving grain boundary discontinuity while integrating the process into the existing manufacturing workflow.
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
This design effectively prevents fatigue fractures from propagating to the base layer and restricts alloy component diffusion, enhancing the durability and conformity of the sliding member.
Implementation Method 1
The soft particles deposited in the base layer and existing on a boundary surface between the base layer and the soft layer adhere to the soft layer.
Implementation Method 2
the anodic oxidation film of the soft material is formed on the boundary portion between the crystal grains that have the unique crystal grain structure of the soft particles and the crystal grains that have the unique crystal grain structure of the soft layer
Implementation Method 3
it is possible to refrain the alloy components other than the soft material included in the soft layer from diffusing to the base layer via the soft particles
Data Source
Figure 1
Figure 2~(2B)
Figure 3~(3B)
AI summary
The present invention discloses a sliding member, comprised of a base layer including soft particles made of a soft material softer than a matrix and deposited in the matrix, and a soft layer made of the soft material formed on a surface of the base layer, wherein: a boundary portion is formed between crystal grains that have a unique crystal grain structure of the soft particles and crystal grains that have a unique crystal grain structure of the soft layer.