4j29 Vacuum Kovar Alloy Material Parts for Glass Sealing
Material:
4 j29 / W.N r. 1.3912 / AISI/ASTM F15 / JIS EMAS – 1001
Dimensions: 7-188mm
Material thickness: 0.8-4.0mm
Process: Stamping and machining
Product technical requirements:
After processing, the parts need to be purified by hydrogen furnace, so that the sealed glass surface has no bubbles to remove impurities such as carbon.
Application: Kovar Alloys for glass sealing
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Product Description:
4J29 Vacuum Kovar Alloy Material Parts for Glass Sealing
4J29 (Kovar Alloy) is a controlled expansion iron-nickel-cobalt Fe-Ni-Co alloy for reliable glass-to-metal sealing in vacuum and electronic applications. This alloy has a thermal expansion coefficient matched to borosilicate hard glass (4.6-5.5 x 10-6/degree C in 20-450 degrees C) which allows for stress-free bonding after cooling, a prerequisite for hermetic seals in high precision environments.
Key Features
1.Thermal Expansion Compatibility
The linear expansion is similar to silicon-boron hard glass (e.g., Pyrex) over a wide temperature range (20–450°C) and so the thermal stress is minimized and the seal does not fail.
The non-linear expansion curve is in good agreement with the behavior of glass, and hence is stable during thermal cycling.
2.Superior Oxidation & Bonding Properties
Forms a dense oxide layer (NiO/CoO) that reacts chemically with the molten glass to provide hermetic seals. When they are perfectly oxidized they turn gray-blue ; when weakly bonded they turn metallic or black .
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 drawing or stamping parts.
Available in rods from 5 to 180 mm, sheets from 0.2 to 40 mm, tubes from capillary to 120 mm OD, wires, and custom forgings.
Applications
4J29 is well known 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) leadframes Relay shells
3.Aerospace & Defense: Hermetic connectors, sensor housings, aerospace grade glass-to-metal seals.
4.Scientific Instruments: Parts for vacuum systems and mercury discharge devices.
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: Custom 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?
Your trusted partner for reliable glass-metal seals in the most extreme environments, precision engineered and proven in aerospace, electronics and scientific instrumentation.
For more specific details or custom requirements, please contact us with your technical parameters (dimensions, quantity, delivery terms).
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FAQ
You can tell us your needs (such as specifications, quantities, materials, drawings, etc.) by email(info@prekovar.com), phone or by submitting the form on our website.
With over 10 years of specialized focus on Kovar/alloy processing, we master the unique challenges of this low-expansion material. Our advanced stamping techniques ensure micron-level accuracy, ideal for critical applications in electronics, aerospace, and hermetic sealing components.
