The hardness of ceramic fiber board is related to the following factors:
Material composition: Ceramic fiber boards are usually composed of ceramic fibers sintered at high temperatures and suitable reinforcing materials. Different material compositions can affect their hardness.
Fiber density: The hardness of ceramic fiberboard is related to the density of its fibers. The higher the fiber density, the closer the bonding between fibers, and the corresponding increase in hardness.
Sintering temperature: The hardness of ceramic fiber board is related to its sintering temperature. Sintering at high temperatures can make the structure of ceramic fiber boards more dense, thereby increasing their hardness.
Additives: During the preparation process of ceramic fiber board, some reinforcing agents or other additives may be added, which can change the hardness of the ceramic fiber board.
Structural design: The hardness of ceramic fiber board is also related to its structural design. For example, increasing the thickness of fiberboard or using multiple layers of fiberboard can increase its hardness.

It should be noted that the above factors are only general influencing factors, and the specific hardness is also influenced by other factors, such as preparation process, sintering time, etc. The hardness of ceramic fiber boards from different manufacturers may also vary.