ASTM B702 Tungsten-Copper Electrical Contact Material
- Grade: Class A (WCu 50/50), Class B (WCu60/40), Class C (WCu70/30), Class D (WCu 75/25), Class E (WCu 80/20)
WCu 55/45, WCu 56/40, WCu 65/35, WCu 68/32, WCu 68/32 HT, WCu 75/25 HT, WCu 78/22, WCu 85/15, WCu 90/10 - Shapes: Plate, Sheet, Rod, Bar, Tube, Wire
Features
ASTM B702 Tungsten-Copper Electrical Contact Material
Chemical Composition (wt.%)
| Elements | Class A | Class B | Class C | Class D | Class E |
| Copper, % | 48–52 | 38–42 | 28–32 | 23–27 | 18–22 |
| Tungsten, % | balance | balance | balance | balance | balance |
| Additives (Individual or total), max, % | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
Physical Properties
| Hardness, Rockwell B | 69–83 | 77–90 | 85–98 | 89–102 | 94–106 |
| Density, Mg/m³ at 96% theoretical | 11.7 | 12.7 | 13.7 | 14.3 | 15 |
| Electrical Conductivity, C % IACS | 56–64 | 49–57 | 44–52 | 41–48 | 38–45 |
| Electrical Conductivity, D % IACS | 38–56 | 34–49 | 29–43 | 27–41 | 25–37 |
| Tensile Strength, ksi (MPa) | 50–60 (344–413) | 55–65 (379–448) | 75–85 (516–585) | 85–95 (585–654) | 90–100 (620–689) |
| Modulus of Rupture, ksi (MPa) | 75–85 (517–586) | 110–120 (758–827) | 130–140 (896–965) | 140–150 (965–1034) | 150–160 (1034–1103) |
| Coefficient of Expansion, in./in. | 7.2 x 10-6 | 6.6 x 10-6 | 5.7 x 10-6 | 5.3 x 10-6 | 4.9 x 10-6 |
| °F m/m·K | 13 x 10-6 | 11.9 x 10-6 | 10.3 x 10-6 | 9.5 x 10-6 | 8.8 x 10-6 |
Technical Specifications
| Specification | Value |
| Standard | ASTM B702 Copper-Tungsten Electrical Contact Material |
| Grade | Class A (WCu 50/50), Class B (WCu60/40), Class C (WCu70/30), Class D (WCu 75/25), Class E (WCu 80/20) WCu 55/45, WCu 56/40, WCu 65/35, WCu 68/32, WCu 68/32 HT, WCu 75/25 HT, WCu 78/22, WCu 85/15, WCu 90/10 |
| Type | Plate, Sheet, Rod, Bar, Tube, Wire |
| Finish | Clean, smooth surface finish |
| Dimension | Plate Thickness: 1-50 mm x Width: 50-1000 mm x Length: 50-2000 mm Sheet Thickness: 0.5-10 mm x Width: 50-1000 mm x Length: 50-2000 mm Rod Diameter: 2-100 mm x Length: 50-2000 mm Bar Width: 5-200 mm x Thickness: 5-100 mm x Length: 50-2000 mm Tube OD: 5-150 mm x WT: 0.5-10 mm x Length: 50-2000 mm Wire Diameter: 0.01 – 20mm |
| Manufacturing Process | Plate and Sheet: Hot-rolled, Cold-rolled |
| Rod and Bar: Hot-rolled, Cold-rolled | |
| Inspection Certificate | EN 10204 Type 3.1 (Mill Test Certificate), EN 10204 Type 3.2 (Witness Testing or 3rd Party Inspection) |
| Tests | Chemical analysis, tensile test, hardness test, and other non-destructive test (Hydrostatic, Pneumatic, and Ultrasonic tests) |
Key Properties
High Electrical Conductivity: Tungsten-copper alloys exhibit excellent electrical conductivity, allowing efficient current transfer in electrical applications.
High Thermal Conductivity: These alloys provide superior thermal conductivity, enabling effective heat dissipation and maintaining the stability of electrical contacts under high current loads.
High Melting Point: The presence of tungsten gives the alloy a high melting point, making it suitable for applications exposed to extreme temperatures without degrading the material’s properties.
High Density: The high density of tungsten-copper alloys contributes to their robustness and durability, essential for high-stress electrical applications.
Excellent Arc Erosion Resistance: These alloys possess remarkable resistance to arc erosion, which prolongs the lifespan of electrical contacts by minimizing material loss during electrical arcing events.
Good Mechanical Strength: Tungsten-copper alloys offer high mechanical strength and hardness, ensuring reliable performance and wear resistance in demanding electrical environments.
Low Thermal Expansion: The low coefficient of thermal expansion ensures dimensional stability and reduces the risk of material deformation under varying thermal conditions.
Resistance to Weld and Fusion: These alloys resist welding and fusion, reducing the likelihood of contacts sticking or bonding during high-current operations, which can cause contact failure.
Customizable Composition: The composition of tungsten and copper can be adjusted to tailor the material properties for specific applications, providing flexibility in design and performance optimization.
Good Machinability: Despite their hardness and strength, tungsten-copper alloys can be machined relatively easily, allowing for the manufacture of complex and precise contact components.
Packing
Packed in plywood boxes.
Application
Electrical Contacts and Electrodes
- Switchgear Components: Used in high-voltage and medium-voltage circuit breakers, relays, and switches due to its excellent arc resistance and ability to withstand high temperatures.
- Electrodes for Electrical Discharge Machining (EDM): The alloy’s high melting point and good electrical conductivity make it ideal for EDM, where precision and durability are crucial.
- Resistance Welding Electrodes: Utilized in resistance welding for its ability to conduct high current and resist wear and deformation.
Heat Sinks and Thermal Management
- Heat Sinks in Electronic Devices: W-Cu alloys are used in heat sinks for high-power semiconductor devices, such as power transistors, thyristors, and integrated circuits, to efficiently dissipate heat.
- Base Plates for Power Modules: The alloy’s thermal conductivity helps manage the heat generated in power modules, improving performance and reliability.
Aerospace and Defense
- Thermal Management in Spacecraft: Employed in components that require efficient heat dissipation and thermal stability under extreme conditions, such as satellite heat shields and components in spacecraft.
- Missile Components: Used in missile nose cones and other high-temperature components due to its ability to withstand extreme heat and mechanical stress.
Electrical and Electronic Packaging
- Substrates for Microelectronics: The alloy is used as a substrate material in microelectronic packaging, providing a stable platform with good thermal conductivity for the mounting of semiconductor devices.
- Hermetic Seals: Employed in hermetic sealing applications for their reliability and stability, ensuring the protection of electronic components from environmental factors.
Power Distribution and Control
- Busbars and Conductors: Utilized in busbars and conductors for high-current applications, benefiting from its low thermal expansion and high conductivity.
- Switch Contacts: Used in industrial power distribution systems where durability and reliability under high-load conditions are essential.
Medical Equipment
- X-Ray Tube Components: Tungsten-copper alloys are used in the anodes and other critical components of X-ray tubes due to their excellent thermal conductivity and ability to withstand high temperatures.
- Electrodes in Medical Devices: Utilized in certain types of medical devices where precise electrical conductivity and thermal management are required.
Industrial Applications
- Electroplating Electrodes: The alloy’s properties are beneficial in electroplating processes where stable electrical conductivity and resistance to wear are necessary.
- Cutting and Machining Tools: Used in specialized cutting tools and machining applications where high wear resistance and thermal stability are required.
