Characteristics of Commonly Used Heating Elements in Vacuum Furnaces

When working with a vacuum furnace, the main purpose is heating. During the heating process, a fast heating rate is required. 

The selected heating material must have good thermal conductivity, and it should not deform or cause a large amount of heat 

loss at high temperatures. It is necessary to ensure that its performance remains stable for a certain period during use. When 

selecting a heating element, it is also necessary to consider the chemical properties of the product to be processed according 

to one's own needs, so as to prevent the material of the heating element from affecting the quality of the workpiece. Therefore,

 it is necessary to select the heating element reasonably.

What are the types and characteristics of non-metallic electric heating materials?

1. The main non-metallic electric heating materials include graphite (in the form of cloth, tubes, and rods). Its characteristics are low

 cost, easy processing, large radiation area, and good resistance to thermal shock. It mainly relies on radiation for heat transfer and

has good working conditions. However, it is prone to volatilization at high temperatures, and measures should be taken to prevent

 vacuum discharge (below 100V).

2.The main pure metal electric heating materials are molybdenum, tungsten, niobium, etc., which are used in high-temperature vacuum

 furnaces. Due to the large temperature coefficient of resistance, a voltage regulator must be equipped to maintain a constant power.

3.The main electric heating alloy materials are nickel-chromium and iron-chromium-aluminum. They can only be used at 1000°C under a 

pressure of 10⁻¹ Pa and are suitable for medium and low-temperature and low-vacuum furnaces. Nickel-chromium alloy and 

iron-chromium-aluminum alloy can only be used at relatively low temperatures and in the medium vacuum range in a vacuum environment;

 molybdenum, tantalum, and tungsten are prone to volatilization when heated in a vacuum, and their corresponding service temperatures are 

reduced; the service temperature of silicon carbide rods in a vacuum is 1400°C, and it can reach 1600°C for a short time. Silicon-molybdenum

 rods will soften at 1300°C in a vacuum; graphite electrodes will volatilize rapidly when the temperature exceeds 2400°C in a vacuum.