Nichrome
Encyclopedia
Nichrome is a non-magnetic alloy
of nickel
, chromium
, and often iron
, usually used as a resistance wire. Patented in 1905, it is the oldest documented form of resistance heating alloy. A common alloy is 80% nickel and 20% chromium, by mass, but there are many others to accommodate various applications. It is silvery-grey in colour, is corrosion-resistant, and has a high melting point
of about 1400 °C
(2552 °F
). Due to its relatively high electrical resistivity
and resistance to oxidation at high temperatures, it is widely used in electric heating element
s, such as in hair dryers, electric oven
s, soldering iron, toaster
s, and even electronic cigarettes. Typically, Nichrome is wound in coils to a certain electrical resistance
, and current is passed through to produce heat.
industry as a bridgewire
in electric ignition systems, such as electric match
es and model rocket
igniters.
Industrial and hobby hot wire foam cutters
use nichrome wire.
Nichrome wire is commonly used in ceramics as an internal support structure to help some elements of clay
sculptures hold their shape while they are still soft. Nichrome wire is used because of its ability to withstand the high temperatures that occur when clay work is fired in a kiln
.
Nichrome wire is used in testing the colour of the flame in the non-luminous part of fire of a cation such as the cations of potassium, copper, calcium, sodium etc.
The alloy
tends to be expensive due to its high nickel
content. Distributor pricing is typically indexed to commodity market prices for nickel.
Other areas of usage include motorcycle silencer
s, and in certain areas in the microbiological lab apparatus.
For heating, resistance wire must be stable in air when hot. Nichrome wire forms a protective layer of chromium oxide
.
NiCrA
NiCrC
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
of nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
, chromium
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
, and often iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, usually used as a resistance wire. Patented in 1905, it is the oldest documented form of resistance heating alloy. A common alloy is 80% nickel and 20% chromium, by mass, but there are many others to accommodate various applications. It is silvery-grey in colour, is corrosion-resistant, and has a high melting point
Melting point
The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...
of about 1400 °C
Celsius
Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...
(2552 °F
Fahrenheit
Fahrenheit is the temperature scale proposed in 1724 by, and named after, the German physicist Daniel Gabriel Fahrenheit . Within this scale, the freezing of water into ice is defined at 32 degrees, while the boiling point of water is defined to be 212 degrees...
). Due to its relatively high electrical resistivity
Resistivity
Electrical resistivity is a measure of how strongly a material opposes the flow of electric current. A low resistivity indicates a material that readily allows the movement of electric charge. The SI unit of electrical resistivity is the ohm metre...
and resistance to oxidation at high temperatures, it is widely used in electric heating element
Heating element
A heating element converts electricity into heat through the process of Joule heating. Electric current through the element encounters resistance, resulting in heating of the element....
s, such as in hair dryers, electric oven
Oven
An oven is a thermally insulated chamber used for the heating, baking or drying of a substance. It is most commonly used for cooking. Kilns, and furnaces are special-purpose ovens...
s, soldering iron, toaster
Toaster
The toaster is typically a small electric kitchen appliance designed to toast multiple types of bread products. A typical modern two-slice toaster draws anywhere between 600 and 1200 W and makes toast in 1 to 3 minutes...
s, and even electronic cigarettes. Typically, Nichrome is wound in coils to a certain electrical resistance
Electrical resistance
The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...
, and current is passed through to produce heat.
Uses
Nichrome is used in the explosives and fireworksFireworks
Fireworks are a class of explosive pyrotechnic devices used for aesthetic and entertainment purposes. The most common use of a firework is as part of a fireworks display. A fireworks event is a display of the effects produced by firework devices...
industry as a bridgewire
Bridgewire
A bridgewire, bridge wire, or hot bridge wire is a relatively thin resistance wire used to set off a pyrotechnic composition serving as pyrotechnic initiator. By passing of electric current it is heated to a high temperature that starts the exothermic chemical reaction of the attached composition...
in electric ignition systems, such as electric match
Electric match
An electric match is a device that uses an externally applied electric current to ignite a combustible compound.-Use:Electric matches can be used in any application where source of heat is needed at a precisely controlled point in time, typically to ignite a propellant or explosive...
es and model rocket
Model rocket
A model rocket is a small rocket that is commonly advertised as being able to be launched by anybody, to, in general, low altitudes and recovered by a variety of means....
igniters.
Industrial and hobby hot wire foam cutters
Hot-wire foam cutter
A hot-wire foam cutter is a tool used to cut polystyrene foam and similar materials. The device consists of a thin, taut metal wire, often made of nichrome or stainless steel, or a thicker wire preformed into a desired shape, which is heated via electrical resistance to approximately 200°C...
use nichrome wire.
Nichrome wire is commonly used in ceramics as an internal support structure to help some elements of clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
sculptures hold their shape while they are still soft. Nichrome wire is used because of its ability to withstand the high temperatures that occur when clay work is fired in a kiln
Kiln
A kiln is a thermally insulated chamber, or oven, in which a controlled temperature regime is produced. Uses include the hardening, burning or drying of materials...
.
Nichrome wire is used in testing the colour of the flame in the non-luminous part of fire of a cation such as the cations of potassium, copper, calcium, sodium etc.
The alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
tends to be expensive due to its high nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
content. Distributor pricing is typically indexed to commodity market prices for nickel.
Other areas of usage include motorcycle silencer
Muffler
A muffler is a device for reducing the amount of noise emitted by the exhaust of an internal combustion engine. A US Patent for an Exhaust muffler for engines was granted to Milton and Marshall Reeves in 1897....
s, and in certain areas in the microbiological lab apparatus.
For heating, resistance wire must be stable in air when hot. Nichrome wire forms a protective layer of chromium oxide
Chromium oxide
Chromium oxide may refer to:* Chromium oxide, CrO* Chromium oxide, Cr2O3* Chromium dioxide , CrO2* Chromium trioxide , CrO3* Chromium oxide peroxide, CrO5* Mixed valence species, such as Cr8O21...
.
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 | Units |
|---|---|---|
| Modulus of elasticity | 2.2 × 1011 | Pa |
| Specific gravity Specific gravity Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for... |
8.4 | Dimensionless |
| Density Density The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight... |
8400 | kg/m3 |
| Melting point Melting point The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure... |
1400 | °C Celsius Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death... |
| Electrical resistivity at room temperature Resistivity Electrical resistivity is a measure of how strongly a material opposes the flow of electric current. A low resistivity indicates a material that readily allows the movement of electric charge. The SI unit of electrical resistivity is the ohm metre... |
1.0 × 10−6 to 1.5 × 10−6 | Ωm |
| Specific heat | 450 | Jkg−1°C−1 |
| Thermal conductivity Thermal conductivity In physics, thermal conductivity, k, is the property of a material's ability to conduct heat. It appears primarily in Fourier's Law for heat conduction.... |
11.3 | Wm−1°C−1 |
| Thermal expansion Thermal expansion Thermal expansion is the tendency of matter to change in volume in response to a change in temperature.When a substance is heated, its particles begin moving more and thus usually maintain a greater average separation. Materials which contract with increasing temperature are rare; this effect is... |
14 × 10−6 | °C−1 |
| Standard ambient temperature and pressure used unless otherwise noted. |
||
Additional properties
| AWG American wire gauge American wire gauge , also known as the Brown & Sharpe wire gauge, is a standardized wire gauge system used since 1857 predominantly in the United States and Canada for the diameters of round, solid, nonferrous, electrically conducting wire... | DIA Diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle... -IN Inch An inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot... | 400F | 1000F | 2000F |
|---|---|---|---|---|
| 8 | .128 | 22.4 | 52 | 128 |
| 10 | .102 | 16.2 | 37.5 | 92 |
| 12 | .081 | 11.6 | 26.5 | 65 |
| 22 | .0253 | 2.9 | 5.6 | 12.5 |
| 32 | .0080 | 0.68 | 1.36 | 2.76 |
| 40 | .0031 | 0.24 | 0.43 | 0.79 |
| AWG | DIA-IN | NiCrA | NiCrC |
|---|---|---|---|
| 10 | .102 | 0.06248 | 0.06488 |
| 12 | .081 | 0.09907 | 0.1029 |
| 22 | .0253 | 1.015 | 1.055 |
| 32 | .0080 | 10.16 | 10.55 |
| 40 | .0031 | 67.64 | 70.24 |
| DEG.F | DEG.C | NiCrA | NiCrC |
|---|---|---|---|
| 68 | 20 | 0 | 0 |
| 600 | 315 | 3.3% | 5.2% |
| 1000 | 538 | 6.3% | 8.6% |
| 2000 | 1093 | 6.0% | 10.5% |
NiCrA
- Chemical Composition: 80% Ni, 20% Cr
- Approx. Melting Point: 1400 deg C
NiCrC
- Chemical Composition: 61% Ni, 15% Cr, bal. Fe
- Approx. Melting Point: 1350 deg C