Skip to content
- Heating Elements:
- Typically uses silicon carbide (SiC) rods as heating elements, arranged vertically at the top and bottom of the furnace.
- SiC rods are non-metallic and have resistance that changes significantly during heating.
- To prevent damage, heating below 850 °C should not be too rapid.
- Over time, SiC rods age, increasing resistance and slowing heating, requiring multi-stage adjustable transformers to regulate voltage and power.
- SiC rods have low thermal shock resistance, low high-temperature strength, and are brittle, which limits their length and the furnace chamber size.
- Alternative materials:
- Molybdenum disilicide (MoSi₂) rods, capable of reaching up to 1600 °C, also require adjustable transformers.
- High-temperature resistive alloys can be used as elements for furnaces with slightly lower max temperatures (~1200 °C) but larger power and chamber size for bigger workpieces.
- Furnace Lining (Refractory Structure):
- Typically three layers:
- Inner layer: High-alumina bricks for heat resistance.
- Middle layer: Insulating bricks.
- Outer layer: Insulating filler.
- Optionally, alumina-silicate refractory fibers can be inserted between refractory and insulating layers.
- Furnace Bottom Plate:
- Made of silicon carbide products to withstand high temperatures.
- Workpiece Capacity:
- Standard SiC rod furnaces handle smaller workpieces due to heating element limitations.
- Furnaces with resistive alloy elements can handle larger workpieces due to higher power and larger chamber size.
