Kovar 4J29 NiFe Precision Alloy for Glass & Ceramic Hermetic Sealing
Kovar 4J29 is a professional iron-nickel-cobalt precision low-expansion alloy, also widely known as Fe-Ni-Co glass sealing alloy. Specially engineered for electronic vacuum and precision sealing scenarios, this material features a thermal expansion coefficient highly consistent with hard borosilicate glass and alumina ceramics across a wide temperature range of -80∼C to 450∼C.
Thanks to its stable dimensional consistency, high Curie point and excellent low-temperature structural stability, 4J29 effectively eliminates thermal stress mismatch during high-temperature sealing. It delivers crack-free, high-airtight hermetic bonding for glass-metal and ceramic-metal assemblies, making it the mainstream sealing material for vacuum and precision electronic components.
Chemical Composition
The chemical composition of 4J29 is strictly balanced to ensure stable expansion and reliable sealing.
| Element | Content (wt%) |
|---|---|
| Nickel (Ni) | 28.5 每 29.5 |
| Cobalt (Co) | 16.8 每 17.8 |
| Iron (Fe) | Balance |
| Carbon (C) | ≒ 0.03 |
| Manganese (Mn) | ≒ 0.50 |
| Silicon (Si) | ≒ 0.30 |
| Phosphorus (P) | ≒ 0.020 |
| Sulfur (S) | ≒ 0.020 |
Physical Properties
| Property | Typical Value | Unit |
|---|---|---|
| Density | 8.36 | g/cm³ |
| Melting Point | ~1450 | ∼C |
| Curie Temperature | ~435 | ∼C |
| Electrical Resistivity | ~0.49 | 米次﹞m |
| Thermal Conductivity | ~17 | W/(m﹞K) |
| Coefficient of Thermal Expansion (20每400∼C) | 4.6 每 5.2 | ℅10⁻⁶/∼C |
| Coefficient of Thermal Expansion (20每450∼C) | 5.1 每 5.5 | ℅10⁻⁶/∼C |
| Modulus of Elasticity | ~138 | GPa |
4J29 exhibits a smooth expansion curve from -80∼C to 450∼C. After sealing with hard glass, thermal stress is minimal, allowing the assembly to withstand repeated thermal cycling without cracking.
Mechanical Properties (Annealed, Typical)
| Property | Value |
|---|---|
| Tensile Strength | ≡ 517 MPa |
| Yield Strength (0.2%) | ≡ 276 MPa |
| Elongation | ≡ 30% |
| Hardness | ~75 HRB |
| Reduction of Area | ≡ 50% |
The material has good ductility and cold workability. It can be stamped, deep drawn, bent, and drawn into wire, making it suitable for lead frames, headers, pins, and other precision components.
4J29 Typical Physical Properties
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Matched Thermal Expansion: Similar linear expansion coefficient with hard borosilicate glass at 20∼C每450∼C, ensuring tight and stable sealing performance.
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High Curie Point: Maintains stable physical properties during heating and sealing processes without performance mutation.
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Superior Low-Temperature Stability: Reliable structural integrity under low-temperature and temperature-cycle working conditions.
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Excellent Sealing Compatibility: Perfectly adapts to hard glass sealing and ceramic sealing processes for hermetic component manufacturing.
Applications
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Electric Vacuum Devices: Serves as the core structural sealing material for various electric vacuum equipment, supporting high-airtight vacuum packaging and long-term stable operation.
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Mercury Discharge Instruments: Ideal for precision mercury discharge instruments that require stable expansion rate and high structural accuracy.
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Precision Electronic Components: Widely used for glass sealing and ceramic sealing parts in high-precision electronic and vacuum systems.
ZYTC Alloy Supply Advantages
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Stable Material Performance: ZYTC Alloy＊s Kovar 4J29 products feature uniform thermal expansion coefficient, avoiding sealing cracking and air leakage caused by material inconsistency.
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Strict Quality Control: Each batch undergoes professional physical performance testing to guarantee low-temperature stability and high-precision sealing adaptability.
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Customized Service: We supply diversified 4J29 specifications including strip, bar and wire, supporting customized processing for precision sealing components.
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Professional Technical Support: With years of experience in precision alloy production, we provide reliable material solutions for vacuum sealing and precision instrument manufacturing.
Contact Us
📧 Email: dominic@zytc-steel.com
📲 WhatsApp: +86 13132148618