Platinite

platinite, alloy that is 46% nickel and 54% iron. It is used in the manufacture of electric lightbulbs because its coefficient of expansion, i.e., the rate at which its volume increases with temperature, is the same as that of glass.

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platinite [′plat·ən‚īt]

(mineralogy)

platynite

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Platinite 

a bimetallic wire consisting of an iron-nickel core (58 percent Fe, 42 percent Ni) with a thin coating of copper (about 30 percent of the total weight of the wire).

Platinite has a coefficient of thermal expansion close to that of platinum (about 9 × 10 ^–6 deg^–1) and is used to replace platinum in leads in light bulbs and various vacuum-tube devices to provide a hermetic seal with glass. An iron-nickel alloy containing 54 percent Fe and 46 percent Ni, which is used for junctions with ceramics (Soviet brand 46N alloy), is sometimes also called platinite.

REFERENCES

Liubimov, M. L. Spai metalla so steklom, 2nd ed. Moscow, 1968. Pretsizionnye splavy s osobymi svoistvami teplovogo rasshireniia i uprugosti. Moscow, 1972.