How to Combine Ceramic Fiber Blankets and Boards in Furnaces

Furnace lining design rarely relies on a single material. To achieve optimal thermal efficiency and cost control, engineers often combine different forms of ceramic fiber. The most common combination is using ceramic fiber boards for the hot face and ceramic fiber blankets for the back-up layer.

The Role of the Board (Hot Face)

Pressed ceramic fiber boards are rigid, dense, and provide a flat surface. They are ideal for the hot face because they resist gas flow erosion and offer structural stability. They also provide a clean, solid surface for stacking loads or installing heating elements.

The Role of the Blanket (Back-Up)

Ceramic fiber blankets (needled felt) are flexible and have very low thermal conductivity. Used in the back-up layer, they provide excellent insulation, keeping the furnace shell temperature low. Because blankets come in rolls, they are fast to install over large areas and can easily wrap around complex structures or fill expansion joints.

Designing the Combination

When combining boards and blankets, the hot face board (e.g., 50mm thick) provides the durability, while the back-up blanket (e.g., 50mm thick) provides the thermal barrier.

It is crucial to ensure that the joints between the layers are staggered. Furthermore, using a high-density board on the hot face allows the use of a lower-cost 1260°C blanket on the back-up, optimizing the overall project cost without compromising performance.