4j29 Vacuum Kovar Alloy Material Parts for Glass Sealing

Product Description:

4J29 Vacuum Kovar Alloy Material Parts for Glass Sealing

4J29 (Kovar Alloy) is a specialized iron-nickel-cobalt (Fe-Ni-Co) controlled expansion alloy designed for reliable glass-to-metal sealing in vacuum and electronic applications. Renowned for its matched thermal expansion coefficient with borosilicate hard glass (4.6–5.5 × 10⁻⁶/°C within 20–450°C), this alloy ensures stress-free bonding during cooling, critical for hermetic seals in high-precision environments.

Key Features

1.Thermal Expansion Compatibility

Matches the linear expansion of silicon-boron hard glass (e.g., Pyrex) across a wide temperature range (20–450°C), minimizing thermal stress and preventing seal failure.

Nonlinear expansion curve aligns with glass behavior, enabling stability under thermal cycling.

2.Superior Oxidation & Bonding Properties

Forms a dense oxide layer (NiO/CoO) that chemically bonds with molten glass, ensuring airtight seals. Optimal oxidation is indicated by gray-blue surfaces, while metallic or black hues signal weak bonding.

Resists mercury corrosion, ideal for mercury-containing instruments.

3.Mechanical & Physical Performance

Density: 8.17–8.25 g/cm³

Resistivity: 0.46–0.48 μΩ·m

Tensile Strength: 520 MPa (annealed), 330 MPa (yield).

Curie Point: ~430°C, ensuring magnetic stability.

4.Processing Versatility

Excellent machinability, weldability, and ductility for deep-drawn or stamped components.

Available in multiple forms: rods (5–180 mm), sheets (0.2–40 mm), tubes (capillary to 120 mm OD), wires, and custom forgings.

Applications

4J29 is widely used in high-vacuum and electronic industries:

1.Electron Tubes: Seals for vacuum tubes, X-ray tubes, microwave tubes, and cathode-ray tubes.

2.Semiconductors: Transistor housings, integrated circuit (IC) lead frames, relay shells.

3.Aerospace & Defense: Hermetic connectors, sensor housings, and aerospace-grade glass-to-metal seals.

4.Scientific Instruments: Mercury discharge devices, vacuum system components.

Technical Specifications

Composition:

Ni: 28.5–29.5%, Co: 16.8–17.8%, Fe: Balance

Trace elements (C, Mn, Si, etc.) tightly controlled for stability.

Heat Treatment:

Annealed in hydrogen at 900°C ±20°C (1h) → 1100°C ±20°C (15min) → Slow cooling (≤5°C/min).

International Equivalents:

US: ASTM F15, UNS K94610

EU: Dilver P0, Vacon 12, Nilo K

Japan: KV-1135.

Quality Assurance

Compliant with YB/T 5231-1993 (China) and global standards (ASTM, DIN).

Strictly tested for low-temperature phase stability (no martensite formation after -78.5°C exposure).

Ordering Information

Forms: Customizable rods, sheets, tubes, wires, and precision parts.

Surface Finish: White ,Black, polished, or acid-cleaned.

Certification: Mill test reports and material traceability provided.

Why Choose 4J29 Kovar Alloy?

A trusted solution for reliable glass-metal seals in extreme environments, combining precision engineering with proven performance in aerospace, electronics, and scientific instrumentation.

For detailed specifications or custom requirements, contact us with your technical parameters (dimensions, quantity, delivery terms).