High Precision 4J29 Alloy Wire For Fe-Ni-Co Wire Kovar Type Sealing Alloy

Product Overview:
4J29 alloy wire, also known as a Fe-Ni-Co sealing alloy or Kovar-type wire, is widely used in applications requiring glass-to-metal hermetic sealing. It contains approximately 29% nickel and 17% cobalt, which gives it a controlled thermal expansion closely matched with borosilicate glass. This makes it ideal for use in electronic tubes, vacuum relays, infrared sensors, and aerospace-grade components.

Material Composition:

• Nickel (Ni): ~29%

• Cobalt (Co): ~17%

• Iron (Fe): Balance

• Other elements: trace amounts of Mn, Si, C, etc.

Thermal Expansion (30–300°C): ~5.0 x 10⁻⁶ /°C
Density: ~8.2 g/cm³
Resistivity: ~0.42 μΩ·m
Tensile Strength: ≥ 450 MPa
Elongation: ≥ 25%

Available Sizes:

• Diameter: 0.02 mm – 3.0 mm

• Length: on spools, coils, or cut lengths as required

• Surface: Bright, smooth, oxidation-free

• Condition: Annealed or cold drawn

Key Features:

• Excellent thermal expansion compatibility with hard glass

• Ideal for hermetic sealing in electronic and aerospace applications

• Good weldability and high dimensional accuracy

• Stable magnetic properties under various environmental conditions

• Custom diameters and packaging options available

Typical Applications:

• Vacuum relays and glass-sealed relays

• Infrared and microwave device packaging

• Glass-to-metal feedthroughs and connectors

• Electronic tubes and sensor leads

• Hermetically sealed electronic components in aerospace and defense

Packaging & Shipping:

• Supplied in plastic spools, coils, or vacuum-sealed bags

• Anti-rust and anti-moisture packaging optional

• Shipping available by air, sea, or express

• Delivery time: 7–15 working days depending on quantity

Handling and Storage:
Keep in a dry, clean environment. Avoid moisture or chemical exposure. Re-annealing may be needed before sealing to ensure optimal bonding with glass.