Silicon carbide SiC heating elements

The silicon carbide heating element is a kind of non-metal high temperature electric heating element. It is made of selected super quality green silicon carbide as main material, which is made into blank, silicided under high temperature and re-crystallized. Compared with metal electric heating elements, this kind of sic heating elements is characterized by high-applied temperature, anti-oxidization, easy installation and maintenance. Therefore, it is widely used in various high temperature electric furnaces and other electric heating devices, such as in the industries of magnet, ceramice, powder metallurgy, glass metallurgy and machinery, involving magnetic, etc.

We adopt new production process of cold ends so that our Silicon carbide heating elements have more excellent specific rate of heat zone resistance and cold end resistance, saving energy, long life, avoiding over-temperature of cold ends to damage the furnace body. The commercial name of our SiC heating elements is HT heater.

silicon carbide heating elements are manufactured from recrystallized high purity alpha silicon carbide rod or tubular form. Optimized structure of SiC particles make it have special characteristics as applied in industry and lab, which have the best service life particularly in oxidation and/or corrosive atmospheres. SiC heating elements may be mounted either vertically or horizontally at the Max operation temperature 1600℃ without any special supports, the elements will not deform. This provides a flexible furnace design for maximum interior design. Another feature is that elements can be replaced when the furnace is in continuous operation, thus avoiding a shutdown. Its high loading capacity is suitable for low-volume and high power conditions. Therefore, silicon carbide heating elements is widely used in various high temperature electric furnaces and other electric heating devices.

We utilize modern production processes and technology. Hot zone and cold ends are connected by using specialized SiC binding materials, and then we treat the welded section with a second siliconized application at high temperature, which improves the strength of the weld greatly and can provide customers with high quality heating elements. Meanwhile, the resistivity of hot zone is much higher than cold ends, as a result, SiC heating elements have excellent hot and cold resistance rate and feature energy-efficiency and energy savings. The commercial name of our silicon carbide heating elements is HT heater. HT heater can be operated at up to 1600℃ in clean dry air but the service temperature will be limited by gases such as nitrogen, ammonia, hydrogen. Other possibilities exist as well.

Chemical properties of SiC heating elements

The silicon carbide elements begin to  oxidize when heated up to 800 C in air, a SiO2 protective  film  forms on the  surface of the hot zone when the temperature reaches 1000~1300℃; Cristobalite will be crystallized at 1300℃; The protective  film  gets to a certain thickness at 1500℃ which  makes the elements oxidation speed very slowly. If heating exceed 1000℃, the protective  film will be destroyed and oxidation will become more rapid and will make the element fail prematurely.

Even though the element oxidizes very slowly during operation, it also causes the resistivity of the element to change as it ages.  To retard the aging speed, for certain atmospheric conditions, we can provide different protection coats which will improve the service life of the silicon carbide heating elements.

Technical data of SiC heating elements

Operating Temperatures

HT SiC heating elements can operate in air(oxidizing) at the furnace temperature of up to 1550℃. Elements can also be used in a reducing or neutral atmosphere but at lower temperatures. The recommended operating temperatures for silicon carbide heating elements in different process atmospheres are as follows.