Glass sealed and controlled expansion Kovar alloys
* kovar alloy, ASTM F15, Nilo-K, UNS K94610 (FeNi29Co17), Chinese 4J29
*Specifications:ASTM F15; DIN 17745; S.E.W. 385; Werkstoff Nr. 1.3981; AFNOR NF A54-301
Kovar Alloy, also know as ASTM F-15, NILO K, Pernifer 2918, Rodar, and Dilvar P1 is Nickel-Iron-Cobalt, controlled expansion alloy containing 29% Nickel.
It’s coefficient of expansion (which decreases with rising temperature to the inflection point), matches the expansion rate of borosilicate glasses and aluminia ceramics.
Applications include glass to metal seals in applications requiring high reliability or resistance to thermal shock, ie.high~power transmitting valves, transistor leads and heaters and photography flash bulbs.
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Specifications
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| Rod | Strip | Wire | Sheet |
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| Item | 1J33 | 3J01 | 3J9 | 4J29 | 4J32 | 4J33 | 4J45 | FeNi50 | Invar36 |
| C | ≤0.05 | ≤0.05 | 0.22-0.26 | ≤0.03 | ≤0.05 | ≤0.03 | ≤0.05 | ≤0.05 | ≤0.1 |
| Mn | ≤0.05 | ≤1.00 | 1.80-2.20 | ≤0.5 | 0.2-0.6 | ≤0.5 | ≤0.8 | ≤0.8 | ≤0.5 |
| Fe | Rest |
| P | ≤0.020 | ≤0.020 | ≤0.03 | ≤0.02 | ≤0.02 | ≤0.02 | ≤0.02 | ≤0.02 | ≤0.006 |
| S | ≤0.020 | ≤0.020 | ≤0.020 | ≤0.02 | ≤0.02 | ≤0.02 | ≤0.02 | ≤0.02 | ≤0.04 |
| Si | 0.30-0.6 | ≤0.80 | 1.30-1.70 | ≤0.3 | ≤0.2 | ≤0.3 | ≤0.3 | ≤0.3 | ≤0.35 |
| Ni | 32.8-33.8 | 34.5-36.5 | 9.0-10.5 | 28.5-29.5 | 31.5-33 | 28.5-29.5 | 44.5-45.5 | 49.5-50.5 | 35-38 |
| Al | 1.0-2.0 | 1.00-1.80 | -- | -- | -- | -- | ≤0.1 | ≤0.1 | -- |
| Co | -- | -- | -- | 16.8-17.8 | 3.2-4.2 | 16.8-17.8 | - | - | - |
| Ti | - | 2.70-3.20 | - | - | - | - | - | - | - |
| Cu | - | -- | -- | -- | ≤0.2 | 0.4-0.8 | ≤0.2 | -- | -- |
| Cr | -- | 11.5-13.0 | 19.0-20.5 | ≤0.2 | -- | ≤0.2 | -- | -- | -- |
| Mo | -- | -- | 1.60-1.85 | ≤0.2 | -- | ≤0.2 | -- | -- | -- |
Kovar strip is a type of nickel-iron-cobalt alloy with a coefficient of thermal expansion similar to that of hard borosilicate glass. It has excellent thermal and mechanical properties, making it widely used in various fields, including:
1. Electronics industry: Kovar strips are commonly used in the electronics industry for the manufacture of vacuum tubes, cathode ray tubes (CRTs), microwave tubes, and other electronic components. The low coefficient of thermal expansion of Kovar ensures that the electronic components maintain their shape and size under varying thermal conditions.
2. Aerospace industry: Kovar strips are used in the aerospace industry for the manufacture of aircraft and spacecraft components, especially those that require high thermal stability and dimensional stability. The low coefficient of thermal expansion of Kovar makes it an ideal material for use in critical aerospace applications.
3. Optical industry: Kovar strips are used in the optical industry for the manufacture of optical filters, mirrors, and lenses as they have excellent thermal stability and low thermal expansion.
4. Automotive industry: Kovar strips are used in the automotive industry for the manufacture of sensors, switches, and other electronic components that require high dimensional stability and thermal stability.
In summary, Kovar strip is a versatile material with a wide range of applications in various industries that require high thermal stability, low thermal expansion, and good mechanical properties.
