Ceramic Insulation for Box Furnaces

Ceramic Insulation for Box Furnaces
Box furnaces are ubiquitous heat treatment components in laboratory and industrial facilities. They are widely available in floor standing and benchtop variations and are routinely used to treat single products, or individual batches, at temperatures exceeding 1200°C (2192°F). Ceramic insulation is subsequently used to improve thermal uniformity throughout the processing chamber. This offers the added benefit of limiting heat propagation through the chamber walls, which could be damaging to sensitive components.

In this blog post, we will explore ceramic insulation for box furnaces in more detail.

CERAMIC INSULATION: BOARDS AND BLANKETS
The two standard variations of ceramic insulation for box furnaces are rigid ceramic fiber boards and flexible blankets. These are manufactured using strands of refractory silicate compressed or woven into a lightweight textile, with excellent inherent strength and low thermal conductivity.

To improve the flame impingement properties and provide an element of structural performance, ceramic fiber blankets are often impregnated with a high-performance resin and formed into rigid shapes. These can be easily machined to specification without impacting the thermomechanical qualities that make the ceramic insulation ideal for hot face applications. Multiple ceramic insulation boards can be profiled to fit together into a purpose-built box unit for muffle-type furnaces.

Ceramic fiber board is often used as a secondary form of insulation in box furnaces to support the performance of flat plate heaters.

CERAMIC INSULATION: FLAT-PLATE HEATERS
A flat plate heater is a composite heating element and insulation product that exploits the low thermal mass of ceramic insulation to optimize the radiation of heat through a processing chamber. This utilizes a cast plate ceramic with grooves designed to house wire heaters, which may be fully embedded or partially exposed. Typical heating elements include helical coils, rod overbend, and ribbon heaters.