CERAMIC

CERAMIC

INTRODUCTION

The word ceramic is derived from the Greek word (keramikos). The term covers inorganic non-metallic materials whose formation is due to the action of heat. Up until the 1950s or so, the most important of these were the traditional clays, made into pottery, bricks, tiles and are like, along with cements and glass. Clay based ceramics are described in the article on pottery. A composite material of ceramic and metal is known as cermet. The word ceramic can be an adjective, and can also be used as a noun to refer to a ceramic material, or a product of ceramic manufacture. Ceramics is a singular noun referring to the art of making things out of

materials. The technology of manufacturing and usage of ceramic materials is part of the field of ceramic engineering.

Many ceramic materials are hard, porous and brittle. The study and development of ceramics includes methods to mitigate problems associated with these characteristics, and to accentuate the strengths of the materials as well as to investigate novel applications.

The American Society for Testing and Materials (ASTM) defines a ceramic article as “an article having a glazed or unglazed body of crystalline or partly crystalline structure, or of glass, which body is produced from essentially inorganic, non-metallic substances and either is formed from a molten mass which solidifies on cooling, or is formed and simultaneously or subsequently matured by the action of the heat.”

Types of ceramic materials

For convenience ceramic products are usually divided into four sectors, and these are shown below with some examples:

_Structural, including bricks, pipes, floor and roof tiles

_Refractory, such as kiln linings, gas fire radiant, steel and glass making crucibles

_White wares, including tableware, wall tiles, decorative art objects and sanitary ware

_Technical, is also known as Engineering, Advanced, Special, and in Japan, Fine Ceramics. Such items include tiles used in the Space Shuttle program, gas burner nozzles, ballistic protection, nuclear fuel uranium oxide pellets, bio-medical implants, jet engine turbine blades, and missile nose cones. Frequently the raw materials do not include clays

Examples of ceramic materials

_Barium titan ate (often mixed with strontium titan ate) displays Ferro electricity, 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 conditions can create PTC effects in heating elements.

_Bismuth strontium calcium copper oxide, a high-temperature superconductor

_Boron carbide (B₄C), which is used in some personal, helicopter and tank armor.

_Boron nitride is structurally is electronic 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.

_Bricks (mostly aluminium silicates), used for construction.

_Earthenware, which is often made from clay, quartz and feldspar.

_Ferrite (Fe₃O₄), which is ferrimagnetic and is used in the core of electrical transformers and magnetic core memory.

_Lead zircon ate titan ate is another ferroelectric material.

_Magnesium diboride (MgB₂), which is an unconventional superconductor.

_Porcelain, which usually contains the clay mineral kaolinite.

_Silicon carbide (SiC), which is used as a susceptor in microwave furnaces, a commonly used abrasive, and as a refractory material.

_Silicon nitride (Si₃N₄), which is used as an abrasive powder.

_Steatite is used as an electrical insulator.

_Uranium oxide (UO₂), used as fuel in nuclear reactors.

_Yttrium barium copper oxide (YBa₂Cu₃O_7-x), another high temperature 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.