Modern life is impossible to imagine without a huge variety of electrical appliances. For many of them, the nichrome spiral is the main part - the "heart" of the mechanism. The operation of electronic devices, machine tools, power tools used in everyday life and in large-scale production directly depends on the wire with the original alloy.
Description
In 1905, the American scientist Albert Marsh came up with the idea of combining chromium and nickel. The patented formula was 20% chromium and 80% nickel. The alloy was named nichrome. Initially, there was no master alloy (refractory elements) in the mixture and it was a two-component alloy. Today you can find options with a nickel content of 55%, and chromium from 15%. The impurities are: iron, silicon, manganese, aluminum, titanium, molybdenum, silicon. There are more than ten "recipes" of the metal that fall under the designation nichrome.
Nichromium spiral, having exceptionally high resistivity, has become indispensablecomponent in numerous tools and devices. It is able to withstand high-temperature oxidation in both normal and aggressive conditions. The alloy has this property due to the presence of chromium, which forms a protective oxide film on the surface of the product. She also paints the alloy in a dark color. If you remove (mechanically) the oxidized layer, the shade will change to whitish-gray.
A two-component alloy has no magnetic characteristics, multi-component modifications may have weakened performance. Nichrome spiral is characterized by rigidity and good ductility. The wire is issued with various section from 0, 01 to 10 mm. Main Features:
- electrical resistivity - 1100-1400 Ohm`m;
- melting point up to 1400 degrees (working range - 800-1100 degrees Celsius);
- density - 8200-8500 kg/m3;
- strength - 650-700 MPa.
Material properties meet the highest technological requirements.
Benefits
High and steady demand for nichrome components is due to the amazing qualities of the alloy:
- does not corrode;
- has a light weight;
- easy to process (easy to stamp and weld);
- high heat resistance;
- strong and flexible at the same time;
- is highly resistant to aggressive environments;
- has a long service life.
Another importantthe advantage is the increased resistance to electric current. In practice, this indicator allows you to get more heat with a smaller amount of nichrome (the length of the nichrome spiral is shorter) than from, for example, a steel element. In turn, a smaller amount of metal allows you to reduce the weight and size of the entire apparatus. The most important advantage of nichrome is the combination of all of the above indicators in one material.
Varieties
Nichrome spiral can be made of various modifications of the alloy and be of different thicknesses. The stamps differ in their composition and are (conditionally) divided into three main groups:
- For resistors: Х20Н80 (20% chromium, 80% nickel); Kh20N73YuM-VI (20% chromium, 73% nickel, 3% aluminum, 1.5% molybdenum, up to 0.3% manganese, up to 0.05% titanium, 2% iron, up to 0.05% carbon, melted by vacuum induction method).
- For use below 900 degrees.
- For heating elements with increased resistance to high temperatures: KhN70YU-N (27% chromium, 70% nickel, 3% aluminum, up to 0.3% manganese, up to 0.03% cesium, up to 0.1% barium, up to 1.5% iron, up to 0.1% carbon).
The properties of the alloy depend on the proportions of its constituent components. A large amount of chromium prevents oxidation.
Scope of application
Nichrome wire is one of the most demanded materials on the market of electrical products. A spiral made of this alloy is used in many models of electric heaters. At home, craftsmen use itfor:
- wood burning machine;
- homemade pottery kilns;
- devices for quick heating of some metals in the forge;
- manufacture of the simplest heating structures ("goats");
- homemade welding machines.
The industrial use of nichrome in household appliances is wide: hair dryers, irons, heaters, soldering irons, electric stoves and more. A wire with a large cross section is used for automatic welding units. Such an alloy can be found in laboratory equipment and radio engineering. Nichrome is used where resistance to high temperatures and aggressive environments is required.
