Kovar Alloy (UNS K94610)

Kovar Alloy (UNS K94610) Product Introduction

Overview:
Kovar is a nickel-cobalt alloy, specifically designed for applications requiring a low coefficient of thermal expansion and high mechanical strength. Kovar (UNS K94610) is primarily used in situations where components must maintain dimensional stability over a range of temperatures, especially when combined with glass, ceramics, or other materials with similar thermal expansion properties. Its most notable application is in electronic packaging, including the sealing of metal leads to glass or ceramic materials.

Key Features:

Low Coefficient of Thermal Expansion:

• Kovar has a thermal expansion coefficient closely matched to that of borosilicate glass, making it ideal for sealing metal to glass, as in electronic devices and vacuum tubes.

Mechanical Strength:

• It possesses excellent tensile strength and toughness, even at high temperatures, which is crucial for components that will be subject to mechanical stresses.

Magnetic Properties:

• As a magnetic alloy, Kovar retains its magnetic characteristics even after being exposed to high temperatures, making it suitable for applications where magnetism is required.

Excellent Fabricability:

• Kovar is easy to machine, weld, and form into precise shapes, offering versatility in manufacturing complex components.

Corrosion Resistance:

• The alloy has good resistance to oxidation and corrosion in normal operating conditions, though it should be protected from environments that contain sulfur or chlorine.

Chemical Composition (Typical):

• Nickel (Ni): 29–37%
• Cobalt (Co): 17–21%
• Iron (Fe): Balance
• Manganese (Mn): ≤1%
• Silicon (Si): ≤0.4%
• Carbon (C): ≤0.05%
• Sulfur (S): ≤0.01%
• Phosphorus (P): ≤0.02%

Applications:

Electronic Packaging:

• Used in the sealing of electronic components to glass and ceramic substrates, such as in vacuum tubes, electrical feedthroughs, and semiconductor devices.

Space and Aerospace:

• Components that require dimensional stability over a wide temperature range, such as in satellite technology and missile systems.

Precision Instruments:

• Used in parts of high-precision instruments where thermal expansion matching is critical, including thermocouples and pressure sensors.

Medical Devices:

• Used in medical devices such as implants and sensors, where stable properties over varying temperatures are required.

Vacuum Systems:

• Kovar is used for sealing components in vacuum chambers, ensuring reliable sealing under high temperatures and pressure conditions.

Physical Properties:

• Density: 8.3 g/cm³
• Melting Range: 1375–1410°C (2507–2570°F)
• Coefficient of Thermal Expansion (CTE): ~5.0 x 10^-6/°C (20–300°C)
• Elastic Modulus: ~210 GPa
• Thermal Conductivity: ~14 W/m·K (at room temperature)

Standards and Specifications: Kovar complies with several industry standards, including:

• ASTM A-323: For bars, rods, and sections
• ASTM A-342: For wire
• MIL-PRF-81761: For high-quality metal feedthroughs for vacuum tubes
• ISO 9001: General quality assurance requirements

Advantages:

• Thermal Expansion Match: Ideal for joining metals to glass and ceramics.
• Strength and Toughness: Strong and durable, suitable for high-stress applications.
• Ease of Fabrication: Can be easily machined into intricate components.
• Corrosion Resistance: Good resistance in a wide variety of environments.

Conclusion:
Kovar alloy (UNS K94610) is an essential material for applications where a stable, low coefficient of thermal expansion and high mechanical strength are critical. Its ability to bond with glass and ceramics makes it ideal for use in the electronics, aerospace, and medical industries. Kovar's versatility, combined with its thermal and mechanical properties, ensures its continued relevance in advanced manufacturing applications.

For further inquiries or customized solutions, feel free to contact your supplier or materials expert.