High Precision 4J33 Sealing Wire Controlled Expansion Alloy For Hermetic Packaging

Product Overview

4J33 alloy wire is a precision low-expansion Fe-Ni-Co alloy material specifically designed for hermetic glass-to-metal sealing applications. With approximately 33% nickel and a small amount of cobalt, this alloy offers a thermal expansion coefficient closely matched to hard glass and ceramics. It is widely used in the manufacture of vacuum tubes, infrared sensors, electronic relays, and other high-reliability devices.

Material Composition

• Nickel (Ni): ~33%

• Cobalt (Co): ~3–5%

• Iron (Fe): Balance

• Others: Mn, Si, C (trace amounts)

Thermal Expansion (30–300°C): ~5.3 × 10⁻⁶ /°C
Density: ~8.2 g/cm³
Electrical Resistivity: ~0.48 μΩ·m
Tensile Strength: ≥ 450 MPa
Magnetic Properties: Soft magnetic, good permeability and stability

Available Specifications

• Diameter: 0.02 mm to 3.0 mm

• Surface: Bright, oxide-free

• Delivery form: Coils, spools, or cut length

• Condition: Annealed or cold-drawn

• Custom sizes and packaging available

Key Features

• Excellent match with hard glass for vacuum-tight sealing

• Stable thermal expansion for precision components

• Good corrosion resistance and weldability

• Clean surface finish, vacuum-compatible

• Reliable performance in aerospace and electronic applications

Typical Applications

• Glass-to-metal hermetic seals

• Vacuum tubes and infrared sensors

• Relay housings and electronic packaging

• Optical device enclosures

• Aerospace-grade connectors and leads

Packaging & Shipping

• Standard plastic spool, vacuum-sealed or custom packaging

• Delivery via air, sea, or express

• Lead time: 7–15 working days depending on order size

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.