Why are ceramics considered brittle materials?

Ceramics are characterized by their high compressive strength combined with low tensile strength, which is why they are often classified as brittle materials. This distinction arises from the atomic structure and bonding present in ceramics. In ceramics, the strong ionic or covalent bonds create a rigid structure that can withstand significant compressive forces without deformation. However, when subjected to tensile stress, the microscopic flaws and the inability of the bonds to slide lead to crack propagation, resulting in failure rather than plastic deformation.

This brittleness is evident in the way ceramics fracture under tension; they do not exhibit significant ductility or flexibility. Unlike materials that can deform plastically, ceramics typically break suddenly when the tensile strength limit is reached, making their behavior under stress markedly different from that of ductile materials. The combination of high compressive strength and low tensile strength determines their applications and limits in construction and manufacturing.