A Nickel-Iron-Cobalt, controlled expansion alloy containing 29% Nickel. Its coefficient of expansion (which decreases with rising temperature to the inflection point), matches the expansion rate of borosilicate glasses and alumina ceramics.
Nilo® K is also known as Kovar, Dilver, and Pernifer 2918.
| Chemical Composition | Specifications | Designations | Key Features | Typical Applications | ||||||||||||||||||||||||||||||||||||||||||
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ASTM F15 | W.NR 1.3981 UNS K94610 AWS 094 |
Controlled coefficient of expansion (which decreases with rising temperature to the inflection point). Matches the expansion rate of borosilicate glasses and alumina ceramics. |
Glass to metal seals in applications requiring high reliability or resistance to thermal shock, ie. high power transmitting valves | ||||||||||||||||||||||||||||||||||||||||||
| Density | 8.16 g/cm³ | 0.295 lb/in³ |
| Melting Point | 1450°C | 2640°F |
| Inflection Point | 450°C | 840°F |
| Thermal Conductivity | 16.7 W/m•°C | 116 btu•in/ft2•h°F |
| Coefficient of Expansion | 6.0 µm/m °C (20 – 100°C) 4.6 – 5.2 µm/m °C (20 – 400°C) |
3.3 x 10-6 in/in °F (70 – 212°F) 2.6 – 2.9 x 10-6 in/in °F (70 – 752°F) |
| Heat Treatment of Finished Parts The Nilo alloys are usually supplied and used in the annealed condition (residual cold work distorts the coefficients of thermal expansion). Annealing times may vary due to section thickness. Oxidizing time and temperature to be selected depending on required oxide thickness. |
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|---|---|---|---|---|---|
| Type | Temperature | Time (Hr) | Cooling | ||
| °C | °F | ||||
| Anneal | 850 – 1000 | 1560 – 1830 | 0.5 | Air or water | |
| To prepare for glass to metal sealing | Decarburization | 900 – 1050 | 1650 – 1920 | 1 | Air or water |
| If a metal oxide interface is required (time and temperature depend on required oxide thickness) |
Oxidize | 600 – 1000 | 1110 – 1830 | 1 | Air |
| Properties | ||||
|---|---|---|---|---|
| Condition | Approx. tensile strength | Approx. operating temperature | ||
| N/mm² | ksi | °C | °F | |
| Annealed | 450 – 550 | 65 – 80 | up to +400 | up to +750 |
| Hard Drawn | 700 – 900 | 102 – 131 | up to +400 | up to +750 |
The above tensile strength ranges are typical. If you require different please ask.
*Trade name of Special Metals Group of Companies
