Ceramics

The word ceramic is derived from the Greek word Κεραμεικος (the name of a suburb of Athens), and in its strictest sense refers to clay in all its forms. However, modern usage of the term broadens the meaning to include all inorganic non-metallic materials. Up until the 1950s or so, the most important of these were the traditional clays, made into pottery, bricks, tiles and the like, along with cements and glass. The traditional crafts are described in the article on pottery. A composite material of ceramic and metal is known as cermet.

Examples of Ceramic Materials

• Silicon nitride (Si₃N₄), which is used as an abrasive powder.
• Boron carbide (B₄C), which is used in some helicopter and tank armor.
• Boron_nitride is structurally isoelectronic to carbon and takes on similar physical forms: a graphite-like one used as a lubricant, and a diamond-like one used as an abrasive.
• Barium titanate (often mixed with strontium titanate) displays ferroelectricity, meaning that its mechanical, electrical, and thermal responses are coupled to one another and also history-dependent. It is widely used in electromechanical transducers, ceramic capacitors, and data storage elements. Grain boundary phenomena in these materials can give rise to PTC behavior for heating elements.
• Lead zirconate titanate is another ferroelectric material.
• Silicon carbide (SiC), which is used as a susceptor in microwave furnaces, a commonly used abrasive, and as a refractory material.
• Magnesium diboride (MgB₂), which is an unconventional superconductor.
• Zinc oxide (ZnO), which is a semiconductor, and used in the construction of varistors.
• Zirconia, which in pure form undergoes many phase changes between room temperature and practical sintering temperatures, can be chemically "stabilized" in several different forms. Its high oxygen ion conductivity recommends it for use in fuel cells. In another variant, metastable structures can impart transformation toughening for mechanical applications; most ceramic knife blades are made of this material.
• Ferrite (Fe₃O₄), which is ferrimagnetic and is used in the core of electrical transformers and magnetic core memory.
• Steatite is used as an electrical insulator.
• Bricks (mostly aluminium silicates), used for construction.
• Uranium oxide (UO₂), used as fuel in nuclear reactors.
• Yttrium barium copper oxide (YBa₂Cu₃O_7-x), a high temperature superconductor.