Expansion Precision Alloy Wire 4j29 4j32 4j36 4j42 Iron Nickel Cobalt Alloy

Expansion Precision Alloy Wire 4j29 4j32 4j36 4j42 Iron Nickel Cobalt Alloy

1.Kovar, is a nickel-cobalt ferrous alloy compositionally identical to Fernico 1, designed to have substantially the same thermal expansion characteristics as borosilicate glass (~5 × 10⁻⁶ /K between 30 and 200 °C, to ~10 × 10⁻⁶ /K at 800 °C) in order to allow a tight mechanical joint between the two materials over a range of temperatures. Corresponding to GB 4J29, ASTM F15, UNS K94610); KOVAR is a hard glass iron-based seal bond containing 29% nickel and 17% cobalt. It finds application in glass-to-metal seals in scientific apparatus, and conductors entering glass envelopes of electronic parts such as vacuum tubes (valves), X-ray and microwave tubes and some lightbulbs.

The alloy is a typical fe-ni-co hard glass sealing alloy commonly used in the world. It has been used for a long time in an aviation factory and its performance is stable. Mainly used in electric vacuum components such as tubes, oscillation tubes, ignitron, magnetron, transistors, the wires of a sealing plug, relays, integrated circuits, chassis, casing glass seal, support, etc.In application, the selected glass should match the expansion coefficient of the alloy.The microstructure stability at low temperature was examined strictly according to the temperature used.Proper heat treatment should be

carried out in the process to ensure the material has good deep penetration and elongation. Air tightness should be strictly checked when using forged materials.

2.Invar, also known generically as FeNi36 (64FeNi in the US), is a nickel-iron alloy notable for its uniquely low coefficient of thermal expansion (CTE or α). The name Invar comes from the word invariable, referring to its relative lack of expansion or contraction with temperature changes.

Like other nickel/iron compositions, Invar is a solid solution; that is, it is a single-phase alloy, consisting of around 36% nickel and 64% iron.

Common grades of Invar have a coefficient of thermal expansion (denoted α, and measured between 20 °C and 100 °C) of about 1.2 × 10⁻⁶ K⁻¹ (1.2 ppm/°C), while ordinary steels have values of around 11–15 ppm. Extra-pure grades (<0.1% Co) can readily produce values as low as 0.62–0.65 ppm/°C. Some formulations display negative thermal expansion (NTE) characteristics. Though it displays high dimensional stability over a range of temperatures, it does have a propensity to creep.

Chemical composition