Kovar (Nilo®, Alloy K) / 1.3981 / UNS K94610
NILO alloy K (UNS K94610/W. Nr. 1.3981), a nickel-iron-cobalt alloy containing approximately 29% nickel and 17% cobalt. Its thermal expansion characteristics match those of borosilicate glasses and alumina type ceramics. It is manufactured to a close chemistry range, yielding repeatable properties which make it eminently suitable for glass-to-metal seals in mass production applications, or where reliability is of paramount importance.
Available Forms for Kovar®
- Wire
- Bar
- Sheet
- Plate
- Tube
- Forgings
- Welding Rod
Kovar Properties and Appearance
Chemical Comparison
| Element | Content |
| Carbon (Maximum) | 0.02% |
| Silicon | 0.20 % |
| Cobalt | 17.00 % |
| Manganese | 0.30 % |
| Nickel | 29.00 % |
| Iron | Balance |
Physical Properties
| Properties | Imperial |
| Density | 0.3020 lb/in³ |
Electrical Properties
| Properties | Imperial |
| Electrical Resistivity 70.0 °F | 294.0 ohm-cir-mil/ft |
Thermal Properties
| Properties | Imperial |
| Curie Temperature | 815°F |
| Thermal Conductivity | 120.0 BTU-in/hr/ft2/°F |
| Melting Range | 2,642 °F |
Kovar alloy is magnetic at all temperatures below the Curie point. Magnetic properties depends upon heat treatment; the lower the hardness, the higher the permeability values and lower hysteresis loss. Kovar alloy is manufactured to meet the requirements of ASTM Specification F-15.
Specifications
UNS K94610
Werkstoff Nr 1.3981
DIN 17745
ASTM F 15
AMS 7726 Wire
AMS 7727 Bars and Forgings
AMS 7728 Sheet, Strip and Plate
MIL-I-23011 class 1
AFNOR NF A54-301
S.E.W 385
DILVER P
4J29
Kovar® Applications
As direct Kovar material suppliers, Magellan Metals distributes high-grade Kovar alloy products for a wide range of industries where dimensional changes due to temperature variation must be minimized, some of the applications where UNS K94610 is utilized include:
- Hermetic seals
- Power tubes
- Microwave tubes
- Diodes
- Transistors
- X-ray tubes
