Copper-Based Sliding Material Fatigue Resistance
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Solution Overview
Problem
Copper-based sliding materials for internal combustion engine bearings face challenges in achieving high fatigue resistance due to coarsening of the bismuth phase during the continuous sintering process, which leads to reduced strength and increased likelihood of crack development under dynamic loads.
Innovation Solution
A copper-based sliding material with a Cu alloy layer containing 10 to 30 mass % Bi, 0.5 to 5 mass % of an inorganic compound, and optionally Sn, Ni, Fe, or Ag, where the inorganic compound has a specific gravity of 70 to 130% relative to Bi, is used to suppress coarsening of the Bi phase and enhance fatigue resistance by embedding the inorganic compound in the Bi phase on the surface of Cu alloy powder particles, ensuring isotropic distribution and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Bi content is increased to not less than 10 mass % to obtain high seizure resistance, then seizure resistance is improved, but the Bi phase becomes coarse and fatigue resistance deteriorates
Solution Approach 1:
The patent applies preliminary action by adding an inorganic compound to the Cu alloy powder before sintering. This inorganic compound serves as a nucleation site that controls the solidification of Bi phase during sintering, preventing coarse Bi phase formation even when Bi content is high (10-30 mass%). The inorganic compound is mixed with the Cu alloy powder in advance to ensure uniform distribution and effective control of Bi phase morphology throughout the sintering process.
Solution Approach 2:
The patent changes the physical and chemical parameters of the system by introducing an inorganic compound with specific properties (particle size 0.1-5 μm, specific gravity 0.5-1.5 times that of Bi). This parameter change controls the solidification behavior of Bi phase during sintering, transforming the Bi phase from coarse to fine dispersion. The addition of inorganic compound alters the nucleation and growth parameters of Bi phase, enabling fine Bi phase distribution even at high Bi content.
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 solution effectively reduces the average particle size of the Bi phase to 2 to 15 μm, achieving excellent fatigue resistance and strength in the circumferential direction by preventing Bi phase coarsening and ensuring isotropic distribution, thereby improving the material's resistance to dynamic loads.
Implementation Method 1
a copper-based sliding material produced by a continuous sintering process
Implementation Method 2
The inorganic compound has an average particle size of 1 to 5 μm and a specific gravity of 70 to 130% relative to the specific gravity of Bi
Data Source
AI summary
Provided is a copper-based sliding material including a steel back-metal layer and a Cu alloy layer. The Cu alloy layer contains, by mass %, 10 to 30% of Bi, 0.5 to 5% of an inorganic compound, and the balance being Cu and inevitable impurities. The Cu alloy layer may further contain 0.5 to 5% of Sn and/or at least one element selected from the group consisting of Ni, Fe, P and Ag in a total amount of 0.1 to 10%. The inorganic compound has an average particle size of 1 to 5 μm and a specific gravity of 70 to 130% relative to the specific gravity of Bi. Bi phase is formed in the Cu alloy layer in an average particle size of 2 to 15 μm, and the Bi phase is dispersed in the Cu alloy layer and isotropic.