Our Silicon Carbide (SiC) Heating Elements are available in a variety of sizes and configurations and are typically an extruded tubular rod or cylinder made from high-purity grains of silicon carbide that are fused together by either a reaction-bonding process or a recrystallization process at temperatures in excess of 3900°F (2150°C). The result is a chemically stable material with a low thermal-expansion coefficient and little tendency to deform. During the recrystallization process fine grains of silicon carbide are formed that act as “bridges” or connection points between larger grains, thus forming conductive pathways. The number of bridges formed dictates the material’s resistance – the greater the number, the lower the resistance. This formation process is controlled within the material to develop a consistent electrical resistance.
The resistance of Silicon Carbide (SiC) Heating Elements varies with both temperature and time, the resistance is high when the material is cold, decreasing as temperature rises, reaching a minimum around 800°C and measure 100% resistance at 1050°C, then increasing again as its temperature rises further. When kept at a high temperature, the resistance of the material increases with age.
The rate of ageing is affected by the surrounding atmosphere and depends largely on the operating temperature (power being dissipated). Quoted life relates to maximum power in various temperatures and atmospheres.
When ordering please state the following:
• Hot Zone length
• Overall length
Talfurnco can also supply the following:
• MoSi2 heating element
• Clamps and fasteners
• Graphite Powder and Products
• Silicon nitride bonded silicon carbide products