A. how does porosity affect the strength of ceramics?
Answers
Answer:
At first, in single-phase ceramics with fine-to-medium-grain size, the fracture energy ( γ) decreases as porosity (P) increases, following a similar tendency to the one found for mechanical strength (see Figure 2). Overall, this tendency has been shown in many advanced ceramics with porosity up to 50% [47].
They attributed this behavior to a reduction in the critical flaw size as well as the increasing strut strength in smaller cell sizes.
Meanwhile, Deng et al. investigated the reinforcement mechanisms of fine- and coarse-grain porous SiC and found that the crack-tip blunting mechanism in porous material, increases the fracture toughness of the material. They also noted that the larger the pore size in front of the crack, the more the fracture toughness of the porous ceramic is relative to its fracture strength.