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.

Huona (Shanghai) New Material Co., Ltd. Was established in 2008, currently have three divisions: Magnesium Division, Thermal Spray Division and Functional Material Division.

Magnesium Division produces magnesium metal products. Various models of high-quality magnesium alloy plate, magnesium rods, high-purity magnesium, magnesium plate, magnesium die casting, magnesium extrusion profiles and other metal magnesium and deep processing products.

Thermal spray wire Division offers a wide variety of pure metal and metal alloy wires, including nickel-, iron-, aluminum-, and zinc-based wires for thermal spray projects.

Fuctional Material Division supply electronic packaging COMPONENTS(GTMS, CTMS), soft magnetic alloys and bimetal strip.

Our company is certified by ISO9001 quality system and ISO14001 environmental protection system.

Mission Statement

We try our best to understand and utilize information within the environment. With this competency, we assist customers to create added value and contribute to the development of industry and healthy living.

We strive for "Best, " welcome challenges, and are relentless till we deliver products and solutions.