4. Ceramics

Ceramics are inorganic materials that are composed of metallic and nonmetallic elements which are bonded to each other with ionic or covalent bonds. Ionic bonds are strong and directional, and therefore ceramics have melting temperatures higher than those of metals and polymers which have metallic or covalent bonds, respectively. Ceramics are produced from materials in powder form by application of heat. They are hard, strong, and brittle. Since they do not have any free electrons, they are poor conductors of heat and electricity. There are numerous combinations of the metallic and nonmetallic groups, and the most commonly known nonmetallic groups are oxides, hydrides, carbides, phosphates, sulfides, and silicates. Aluminum oxides, calcium phosphates, and titanium nitrides are in this class. Carbon-based materials such as carbon, graphite, diamond, and graphene are sometimes classified as members of the ceramics group, but in this book, they will be presented in another chapter (Chap. 6).