Catégories: Matériaux chauffants , Éléments chauffants , Matériaux de résistance , Produits de fournaise

There are two main types of electric resistance alloys. Nickel-chromium (e.g. 80 Ni, 20 Cr), called nichrome, was developed around the beginning of the 20th century and was soon used as a heating element material in industrial furnaces as well as in electric household appliances.

In the thirties, Kanthal introduced a new resistance heating alloy (called Kanthal®) based on iron-chromium-aluminum with a longer life and a higher maximum operating temperature than nickel-chromium. Kanthal manufactures both types of alloys under the names Nikrothal® (nickel-chromium) and Kanthal® (iron-chromium-aluminum).

The two main types of alloys have their own specific properties, with advantages and disadvantages, and are supplied in many different grades and forms. In general Kanthal® type alloy is superior to Nikrothal® in respect of performance and life and is therefore nowadays a standard material choice when it comes to metallic heating elements for industrial furnaces.

The Nikrothal® alloy may have special advantages if you need a heating element having very good mechanical properties in the hot state. Kanthal® APM has, however, creep strength at elevated temperatures in the same level as Nikrothal®.

For the furnace user, using Kanthal® results in less amount of element material and also a longer life. The table below shows an example of weight saving obtained by using Kanthal® instead of nickel-chromium alloys. This lower element weight will also result in considerable cost savings regarding the support system, because fewer suspension hooks are necessary.

The most important advantages with Kanthal® type alloy are:

  • Higher maximum temperature of 1425°C compared to 1250°C for Nikrothal®
  • Up to four times longer life
  • Higher surface load
  • Higher resistivity
  • Lower density
  • No spalling oxide, which may contaminate the goods and the furnace and also cause short circuit or failure of elements and gas burners

A 120 kW furnace equipped with ROB elements. Three elements of 40 kW each, 380 V

Element data Nikrothal® Kanthal®
Furnace temperature, °C 1000 1000
Element temperature, °C 1068 1106
Hot resistance, Rw 3.61 3.61
Temperature factor, Ct 1.05 1.06
Cold resistance, R20 3.44 3.41
Wire diameter, mm 5.5 5.5
Surface load, W/cm2 3.09  3.98
Wire length 3 elements, m 224.9 174.6
Wire weight 3 elements, kg 44.4 29.6

Weight saving based on same wire diameter:

kg: 44.4 – 29.6 = 33 %

44.4