Cu-Bi Sliding Member Structure for Seizure and Fatigue Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge is to enhance the seizure resistance of sliding members with Cu-based alloy layers without compromising fatigue resistance, as increasing the amount of Bi in the alloy layer improves seizure resistance but decreases fatigue resistance.
Innovation Solution
A sliding member with a Cu-based alloy layer is designed to have two regions: a first region near the base material with refined Bi phases to improve fatigue resistance and a second region near the sliding surface with larger Bi phases to reduce seizure, achieved through controlled Bi distribution and a specific casting and cooling process, including a heat treatment step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of Bi added to the alloy layer is increased, then seizure resistance is improved, but fatigue resistance decreases
Solution Approach 1:
The patent applies local quality by creating distinct Bi phase distributions in different regions of the alloy layer. The first region (near base material) contains refined Bi phases to improve fatigue resistance, while the second region (near sliding surface) contains coarser Bi phases to reduce seizure. This spatial differentiation of material properties resolves the contradiction between seizure resistance and fatigue resistance.
Solution Approach 2:
The alloy layer is segmented into two functional regions based on Bi phase characteristics. The first region focuses on crack propagation suppression through refined Bi phases, while the second region focuses on seizure prevention through coarser Bi phases. This segmentation allows each region to optimize for its specific function without compromising the other.
2Reliability
If Bi phases are made larger to reduce seizure, then seizure resistance improves, but crack propagation is facilitated reducing fatigue resistance
Solution Approach 1:
Different Bi phase sizes are implemented in different locations: coarse Bi phases (5-50 μm) in the second region near the sliding surface for seizure resistance, and fine Bi phases (0.1-5 μm) in the first region near the base material for fatigue resistance. This local differentiation resolves the contradiction between seizure resistance and fatigue resistance.
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 approach enhances seizure resistance by providing sufficient Bi at the sliding surface while refining Bi phases near the base material to prevent crack propagation, thus maintaining fatigue resistance.
Implementation Method 1
a cooling step of cooling the base material at the other surface than the casting surface with a coolant to solidify the alloy layer in one direction
Implementation Method 2
solidify the alloy layer in one direction
Implementation Method 3
When the temperature of the alloy layer is increased by sliding between the sliding member and a mating material, the Bi phases included in the alloy layer are eluted from the matrix of the alloy layer
Implementation Method 4
the supply rate of the coolant is reduced to thereby control the size and number of the Bi phases included in the alloy layer in the thickness direction of the alloy layer
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A sliding member 10 according to one embodiment includes a base material 11 and an alloy layer 12 including Cu as a main component and Bi and having a sliding surface 14 formed on a side opposite to the base material 11. The alloy layer 12 has a first region and a second region. The first region is set to a region taking up 30% of the thickness of the alloy layer 12 which is from an interface 13 in contact with the base material 11 toward the sliding surface 14. The second region is set to a region taking up 10% of the thickness of the alloy layer 12 which is from the sliding surface 14 toward the base material 11. A larger number of Bi phases having larger cross-sectional areas are distributed in an arbitrary observation cross section as Bi phases included in the second region compared to Bi phases included in the first region.