Question

Why are Ceramics very hard?

Answer 1

Hint: A ceramic is any of a number of hard, brittle, heat-resistant, and corrosion-resistant materials created by moulding and burning a non-metallic mineral like clay at a high temperature. Earthenware, porcelain, and brick are common examples. The adjective "ceramic" can be used to describe a substance, product, or process, or it can be used as a noun, either singularly or as the plural noun "ceramics."

Complete answer:
Any ceramic substance's physical characteristics are determined by its crystalline structure and chemical makeup. Solid-state chemistry reveals the fundamental relationship between microstructure and properties, such as localised density variations, grain size distribution, type of porosity, and second-phase content, all of which can be correlated with ceramic properties like mechanical strength (as determined by the Hall-Petch equation), hardness, toughness, dielectric constant, and the optical properties exhibited by transparent ceramics.
Ceramic material development has developed the class of ceramic matrix composite materials, in which ceramic fibres are incorporated and specialised coatings build fibre bridges across any fracture to overcome the brittle behaviour. This mechanism improves the fracture toughness of such ceramics significantly. Ceramic disc brakes are an example of a ceramic matrix composite material that has been produced utilising a specific method.
Because of the way ceramics are made, they are extremely hard. They're created by heating them to extremely high temperatures and then swiftly cooling them. Due to the fast quenching, there is little time for bonds to form, causing them to become rigid. This is thought to be one of the elements that contributes to the hardness of ceramics.

Note:
Ceramic materials' crystallinity ranges from strongly orientated to semi-crystalline, vitrified, and even totally amorphous (glasses). Most vitrified or semi-vitrified fired ceramics, such as earthenware, stoneware, and porcelain, are vitrified or semi-vitrified. Most ceramic materials are good thermal and electrical insulators due to variations in crystallinity and electron composition in ionic and covalent interactions (researched in ceramic engineering).