Nichrome

Nichrome (NiCr, nickel-chrome, chrome-nickel, etc.) generally refers to any alloy of nickel, chromium, and often iron and/or other elements or substances. Nichrome alloys are typically used in resistance wire. They are also used in some dental restorations (fillings) and in other applications.

Uses

Nichrome is used in a very wide variety of devices where electric heating is required.

Nichrome is used in the explosives and fireworks industry as a bridgewire in electric ignition systems, such as electric matches and model rocket igniters.

Industrial and hobby hot-wire foam cutters use nichrome wire.

Nichrome wire is commonly used in ceramic as an internal support structure to help some elements of clay sculptures hold their shape while they are still soft. Nichrome wire is used for its ability to withstand the high temperatures that occur when clay work is fired in a kiln.

Nichrome wire can be used as an alternative to platinum wire for flame testing by colouring the non-luminous part of a flame to detect cations such as sodium, potassium, copper, calcium etc.

The alloy tends to be expensive due to its high nickel content. Distributor pricing is typically indexed to market prices for nickel.

Other areas of usage include motorcycle silencers, in certain areas in the microbiological lab apparatus, as the heating element of plastic extruders by the RepRap 3D printing community and also in the solar panel deployment mechanism of spacecraft LightSail-A.

For heating, resistance wire must be stable in air when hot. Nichrome wire forms a protective layer of chromium oxide.

Nichrome may be also used as the coils of electronic cigarettes for vaping.

Properties

The properties of nichrome vary depending on its alloy. Figures given are representative of typical material and are accurate to expressed significant figures. Any variations are due to different percentages of nickel or chromium.

Material property Value Unit
Modulus of elasticity 2.2 × 1011 Pa
Density 8400 kg/m3
Melting point 1400 °C
Electrical resistivity at room temperature (1.0—1.5) × 10−6 Ω·m
Specific heat 450 J/(kg·K)
Thermal conductivity 11.3 W/(m·K)
Thermal expansion 14 × 10−6 K−1
Standard ambient temperature and pressure
used unless otherwise noted.

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