Traditional heating wire materials have different characteristics:
(1) Iron-chromium-aluminum wire: the resistance rate is large, the temperature used is high, and the oxidation resistance is superior. It is more commonly used in the production of stainless steel electric heating tubes and the price is cheaper; the heating temperature in air is 900 ~ C to 1100 ~ C.
(2) Nickel-chromium wire: the resistance rate is small, the high temperature resistance is good, and it is easy to weld and process; it is not easy to deform under a high temperature working environment; the maximum heating temperature is about 1050 ~ C.
(3) Other pure metal heating elements: high melting point metals such as tungsten, tantalum, etc., which have a large resistance coefficient and a high melting point, but have poor oxidation resistance in the air and unstable power during operation. The melting point of tantalum can reach about 3000%, but as long as it reaches 600 ℃ under the air, it begins to oxidize violently, and it can generally be used in a vacuum. Its characteristic is high temperature resistance, but it becomes brittle under high temperature working environment and easily breaks. The temperature resistance of tungsten wire can reach about 2900 ~ C, but it will quickly oxidize once exposed to air. Its disadvantage is poor processing performance. The temperature is generally controlled at about 500 ~ C during processing. It can be seen that the oxidation resistance and high temperature resistance are important indicators for measuring the quality of the heating wire. The greater the current and the higher the temperature, the more intense the oxidation strength of the heating wire. In the future, if we can synthesize an electric heating wire material with low cost, higher temperature resistance, oxidation resistance and strong plasticity, it can provide a great help to improve the performance of electric heating tubes.