Industrial ceramics plays a great role in our technology today, it covers all products that are made from inorganic, non metallic materials and having industrial or technical applications. The materials normally consist of substance with high melting or softening point. The term “industrial ceramics” also refers to the science and technology of developing and manufacturing such products. The industrial ceramics are a large group of materials having specialized uses other than domestic or aesthetic. They generally exclude glasses, enamels, building materials and certain cements and refractories. The fundamentals of industrial ceramics derive from its name ceramics, which is a term applied to all useful or ornamental clay objects that are baked.
The use of ceramics in industrial technology starts in the early 19th century, by developing a strong porcelains for high voltage electrical insulations. Steatites and cordierites, also with special electrical and mechanical properties where produces in the 20th century. This products where obtained largely by blending and then heating to high temperatures materials, such as various clays, of variables or uncertain purity. Wide range of new material with specified properties for use in industrial ceramics had an increasing demands in the 1930’s.
Primary Components Of Industrial Ceramics
Melting Point (°C.)
Industrial ceramics has different properties that determine the range and extent of their uses.
Chemical properties. Most industrial ceramics are consist of metals and semimetals with non metals and the common primary components are oxides. A few nitrides, carbides, borides, and compounds containing more than one non metal. Other material that may be regarded as ceramics are the elements silicon and carbon in the form of diamonds and graphite. In general, ceramics are more resistant to oxidation and corrosion than plastic and metals.
Mechanical properties. Most industrial ceramics are strong, that is, they show considerable strength and stiffness under compression and bending. “Bend Strength” is commonly used as a criterion of merit and in design calculation. The highest strength polycrystalline ceramic material are based on zirconium dioxide.
Physical properties. Industrial ceramics are compound of light non metals (oxygen, carbon, or nitrogen) with a lighter metals or semi metals. In general, ceramics have low densities compared with metals. And given the part size the strength-to-weight can be higher than for a metal. Many ceramics are also very hard, and resist wear and abrasion. The hardest material known is diamond, followed by PBN Boat in cubic crystal form.
Thermal properties. Industrial ceramics has a very high melting or softening points. They retain strength and resistance to deformation under load (“creep” resistance) at temperatures higher than those to which many metal can be exposed. However, these brittle material is weak to “thermal shock”, it is a term for the generation of mechanical stress as a result of a sudden and severe change in temperature than can lead to failure.
Electrical properties. Ceramics exhibit a wide range of electrical conductivities. For example, aluminum oxide is a very good insulator, silicon carbide is a semiconductor at room temperature, and compounds such as chromium dioxide conduct electricity as a metal do. The presence of mobile ions in an oxide or silicate may give rise to ionic conductivity, which increases in high temperature. This is said to be the reason why porcelains cannot be use as a insulators at a high temperatures. On the other hand the mobility of ions in certain types of oxide allows materials such as alumina to be use as electrolytes in energy storage device like battery.
Magnetic properties. Ferrites or ceramics containing iron oxide, FeO-can have magnetic properties similar to those of magnetic containing iron, nickel and cobalt. Unlike metals, ferrite can be made with high electrical resistance and can be used at high frequencies without an acceptable loss of power. They can be also made with a high resistance to demagnetization.
Optical properties. The optical characteristic of a ceramic depend on both intrinsic factor (determining color) and extrinsic (governing transparency). The color of a single crystal depends on the amount of ion in the crystal. Most single-crystal oxides transmit some visible lights; semiconducting single-crystal may appear completely black. Transparency is determined by the presence of light-scattering “flaws” such as grain boundaries and internal voids.