CuPb10Sn10 Tin-Lead Bronze Bushing: Lubrication, Wear Resistance, and Corrosion Resistance

In the world of bushings and bearings, the CuPb10Sn10 Tin-Lead Bronze bushing stands out for its exceptional lubrication performance, wear resistance, and corrosion resistance. This alloy is ideally suited for use as a bimetal casting material in various applications where high surface pressures and lateral pressures are encountered. Let’s delve deeper into the characteristics, applications, and manufacturing process of this remarkable material.

Key Characteristics:

1. Exceptional Lubrication Performance: The CuPb10Sn10 alloy’s composition is rich in lead, which doesn’t dissolve in copper-tin alloys. Instead, lead is distributed as discrete particles within the dendritic structure of the alloy. This unique feature significantly enhances the alloy’s wear resistance and machinability. It’s particularly well-suited for applications where lubrication might be less than ideal.

2. High Wear Resistance: This alloy combines the wear resistance of leaded bronze with the thermal conductivity, machinability, corrosion resistance, and strength properties of tin bronze. While it may have lower strength compared to low-lead tin bronzes, it excels in working conditions with a load of 20MPa and a sliding speed of 15m/s, demonstrating excellent wear resistance.

3. Versatile Applications: CuPb10Sn10 Tin-Lead Bronze is used in a range of applications, including sliding bearings subject to high surface pressures and lateral pressures, such as rolling mills, vehicle bearings, components subjected to impact loads up to 60MPa, and bimetal bearings in internal combustion engines with peak pressures reaching 100MPa. It’s also employed in piston pin bushings and friction plates.

CuPb10Sn10 Tin-Lead Bronze Bushing’ Manufacturing and Heat Treatment:

1. Heat Treatment: The alloy cannot be heat-treated for strengthening. Stress relief annealing is recommended at temperatures between 260-300°C.

2. Types and Supply States: CuPb10Sn10 is primarily supplied in the form of castings.

Melting and Casting Process:

1. Melting: When melting the alloy, it’s best done in a weakly oxidizing atmosphere using pre-calcined wood charcoal or crushed graphite as a cover. Induction furnaces or crucible furnaces are commonly used. High-melting-point copper should be pre-deoxidized with phosphor copper, followed by the addition of lead and tin. Proper mixing and a small amount of phosphor copper should be added before pouring to ensure uniform lead distribution and improved fluidity of the melt.

2. Casting: CuPb10Sn10 exhibits a wide crystallization temperature range, with a tendency for dendritic crystallization during solidification. It has good fluidity, which is beneficial for casting. It has low linear shrinkage (1.37% at 1150°C) and does not form significant shrinkage cavities. Since lead is practically insoluble in copper, it can lead to lead segregation during casting. To avoid this, casting methods that induce cooling and promote sequential solidification should be chosen. Suitable casting methods include metal mold casting, semi-metallic casting, water-cooled mold casting, and investment casting. For large components, centrifugal casting is preferred.

3. Mold Design: CuPb10Sn10 has low slag formation, and specialized filtering and slag collection systems are typically not required in the casting system. Closed-top pouring or rain shower-type pouring methods are commonly employed.

4. Pouring Temperature: The pouring temperature should be controlled according to the size of the casting. For small, thin-walled castings, it should range from 1110°C to 1200°C, while for large, thick-walled castings, it should be between 1030°C to 1150°C.

Applications and Special Requirements:

This alloy is mainly used for friction components operating under high loads and high speeds. Common applications include bushings for fuel pumps, kerosene pumps, water pumps, sealing rings, washers, sleeves, bearings, and more.

Chemical Composition:

• Copper (Cu): Remainder
• Tin (Sn): 9.0-11.0
• Zinc (Zn): ≤2.0 (not included in impurities total)
• Lead (Pb): 8.0-11.0
• Phosphorus (P): ≤0.05 (impurities)
• Nickel (Ni): ≤2.0 (not included in impurities total)
• Aluminum (Al): ≤0.01 (impurities)
• Iron (Fe): ≤0.25 (impurities)
• Manganese (Mn): ≤0.2 (impurities)
• Silicon (Si): ≤0.01 (impurities)
• Antimony (Sb): ≤0.5 (impurities)
• Sulfur (S): ≤0.10 (impurities)
• Note: Total impurities ≤1.0

Mechanical Properties Of ZCuPb10Sn10 Bearing Sleeve Bushing:

• Tensile Strength (σb): ≥220 MPa
• Yield Strength (σ): ≥140 MPa
• Elongation (δ5): ≥5%
• Hardness: ≥70 HBW (reference value)

Heat Treatment Specifications:

• Casting Temperature: 1000-1100°C

Casting Methods:

• Metal Mold Casting

In conclusion, the CuPb10Sn10 Tin-Lead Bronze bushing is a versatile material that excels in demanding applications where lubrication, wear resistance, and corrosion resistance are crucial. Its unique composition and manufacturing process make it a reliable choice for a wide range of industrial components and machinery.