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Silicon carbide is an exceptionally hard crystalline compound of silicon and carbon which is synthetically produced. It has historically been used for sandpapers and cutting tools, however, in recent years its use has expanded and it is now frequently being used for heating elements in industrial furnaces as well as in parts for pumps, rocket engines, and in semiconducting substrates for light-emitting diodes.
This article will explore why silicon carbide is such a good choice for heating elements.
General Characteristics of Silicon Carbide
To understand why silicon carbide heating elements are suitable for furnaces, it is important to understand the key characteristics of silicon carbide. It has a Mohs hardness rating of 9, which is almost as hard as diamond. Silicon carbide has an extremely high thermal conductivity, a high-temperature strength, and a low thermal expansion meaning it works extremely well under considerable heat.
Silicon carbide is also resistant to chemical reactions, this means that silicon carbide heating elements can be used without the risk of having an adverse impact on the material being heated.
Increasing Popularity of Electric Heating Elements
Electric heating elements are an extremely popular choice for heat treaters and are available in a range of shapes, sizes, and materials. Silicon carbide heating elements are one of the most commonly used types, finding extensive use across the heat-treating industry when high temperatures and maximum power are required.
Silicon Carbide Heating Elements
A silicon carbide heating element is general a tubular or cylinder which is made from high-purity grains of silicon carbide which are fused together via a reaction-bonding process or a recrystallization process where temperature reach over 3900°F (2150°C).
This results in the creation of a chemically stable material that has a low thermal expansion coefficient and is unlikely to deform. Recrystallization then forms fine grains of silicon carbide which can be used as connection points between larger grains and creating conductive pathways. The number of connections formed directly impacts the material’s resistance, the more connections formed, the lower the resistance.
For a silicon carbide heating element to be able to have a high level of electrical resistance, it is critical that this formation process is controlled.
The life of a silicon carbide heating element is influenced by the furnace atmosphere, watt density, operating temperature, frequency of maintenance, and whether it is in continuous or intermittent service. Silicon carbide heating elements are extremely versatile and can operate at extremely high temperatures.
At Deltech, silicon carbide elements are often used for furnaces designed for operating temperatures up to 1550 degrees Celsius. Most models, for example, the Horizontal Tube Furnace and our Rotary Tube Furnace, may feature silicon carbide elements depending upon the application requirements. If you would like to find out more about our furnaces, contact us today.