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The word ceramic is derived from Greek, 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.Historically, ceramic products have been hard, porous and brittle. The study of ceramics consists to a large extent of methods to mitigate these problems, and accentuate the strengths of the materials, as well as to offer up unusual uses for these materials.
1 Examples of Ceramic Materials
- Silicon nitride ( Si3 N4), which is used as an abrasive powder.
- Boron carbide ( B4 C), which is used in some helicopter and tank armor.
- Silicon carbide ( Si C), which is used as a succeptor in microwave furnaces, a commonly used abrasive, and as a refractory material.
- Magnesium diboride ( MgB2), which is an Unconventional superconductor.
- Zinc oxide ( Zn O), which is a semiconductor, and used in the construction of varistorA varistor is a type of resistor with a significantly non-ohmic current- voltage characteristic. The name is a portmanteau of variable resistor , which is misleading since it is not continuously user-variable like a potentiometer or rheostat, and is not as.
- Ferrite ( FeThis article is about metallic iron. For the ironing device, see ironing manganese iron cobalt Fe Ru Full table General Name, Symbol, Number iron, Fe, 26 Chemical series transition metal Group, Period, Block 8 (VIIIB), 4 , d Density, Hardness 7874 kg/m3,3O4), which is ferrimagneticIn physics, a ferrimagnetic material is one in which the magnetic moment of the atoms on different sublattices oppose as in antiferromagnetism but the opposing momentum are unequal and a spontaneous magnetization remains. This happens when the sublattices and is used in the core of electrical transformers and magnetic core memoryMagnetic core memory or ferrite-core memory is an early form of computer memory. It uses small magnetic ceramic rings, the cores to store information via the polarity of the magnetic field they contain. Such memory is often just called core memory or, inf.
- SteatiteThe name steatite is a type of soapstone which is almost purely talc. It is also a type of ceramic material made from soapstone with minor additives and heated to vitrify. It is often used as an insulator or housing for electrical components, due to its d is used as an electrical insulator.
- Bricks (mostly aluminium silicates ), used for construction.
- Uranium oxide ( UUranium is a chemical element in the periodic table that has the symbol U and atomic number 92. A heavy, silvery-white, toxic, metallic , and naturally- radioactive element, uranium belongs to the actinide series and its isotope uranium-235 is used as theO2), used as fuel in nuclear reactors.
- Yttrium barium copper oxide ( Y Ba2 Cu3 O7-x), a high temperature superconductor.
2 Properties of Ceramics
2.1 Mechanical properties
Ceramic materials are usually ionic or glassy materials. Both of these almost always fracture before any plastic deformation takes place, which results in poor toughness in these materials. Additionally, because these materials tend to be porous, the pores and other microscopic imperfections act as stress concentrators, decreasing the toughness further, and reducing the tensile strength. These combine to give catastrophic failures, as opposed to the normally much more gentle failure modes of metals.
These materials do show plastic deformation. However, due to the rigid structure of the crystalline materials, there are very few available slip systems for dislocations to move, and so they deform very slowly. With the non-crystalline (glassy) materials, viscous flow is the dominant source of plastic deformation, and is also very slow. It is therefore neglected in many applications of ceramic materials.
These materials have great strength under compression, and are capable of operating at elevated temperatures. Their high hardness makes them widely used as abrasives, and as cutting tips in tools.
