Ceramic
Ceramics is the Art of creating useful and/or decorative objects from clay.
Ceramics as a domain of Materials Science
Ceramics is the term used for the study of ceramic materials, both in the traditional sense of pottery, and in a modern sense of oxide- or nitride-based materials.
Examples of Ceramic Materials
Silicon Nitride (Si3N4), which is used as an abrasive powder.
Zinc Oxide ( ZnO ), which is used as a material in a diode for its electrical properties.
Ferrite ( Fe3O4), which is magnetic and is used in the core of electrical transformers.
Bricks ( mostly aluminum silicates ), used for construction.
Uranium Oxide ( UO2), used as fuel in nuclear reactors.
Properties of Ceramics
Ceramic materials are usually hard and strong. However, imperfections in the ceramic make them brittle. Under some conditions, such as extremely low temperature, some ceramics exhibit superconductivity.
Some ceramic materials can withstand extremely high temperatures without losing their strength. These are called refractory materials. They generally have low thermal conductivities, and thus are used as thermal insulators. For example, the belly of the Space Shuttles are made of ceramic tiles which protect the spacecraft from the high temperatures caused during reentry.
A couple of decades ago, Toyota researched on producing a ceramic engine which can run at a temperature of over 6000°. Ceramic engines do not require a cooling system and hence a major weight reduction in fuel effecient vehicles. Fuel effeciency of the engine is also higher at high temperature. In conventional metallic engine, much of the energy released from the fuel must be dissipated as waste heat in order to prevent a meltdown of the metallic parts. Despite all the desirable properties, such engines are not in production because the manufacturing of ceramic parts is difficult. Imperfection in the ceramic leads to cracks. Such engines are possible in laboratory research, but manufacturing difficulties prevent them from becoming reliable products.