Editing Ceramic (section)

==Materials==
[[File:Si3N4thruster.jpg|thumb|upright=1.35|right|Silicon nitride rocket thruster. Left: Mounted in test stand. Right: Being tested with H<sub>2</sub>/O<sub>2</sub> propellants.]]
Ceramic material is an [[Inorganic compound|inorganic]], [[metal]]lic [[oxide]], [[nitride]], or [[carbide]] material. Some elements, such as [[carbon]] or [[silicon]], may be considered ceramics. Ceramic materials are brittle, hard, strong in compression, and weak in [[shear stress|shearing]] and tension. They withstand the chemical erosion that occurs in other materials subjected to acidic or caustic environments. Ceramics generally can withstand very high temperatures, ranging from 1,000&nbsp;°C to 1,600&nbsp;°C (1,800&nbsp;°F to 3,000&nbsp;°F).

[[Image:Ceramic fractured SEM.TIF|thumb|upright=1.2|A low magnification [[Scanning electron microscope|SEM micrograph]] of an advanced ceramic material. The properties of ceramics make fracturing an important inspection method.]]
The [[crystallinity]] of ceramic materials varies widely. Most often, fired ceramics are either [[Vitrification|vitrified]] or semi-vitrified, as is the case with earthenware, [[stoneware]], and porcelain. Varying crystallinity and [[electron]] composition in the ionic and covalent bonds cause most ceramic materials to be good thermal and [[Insulator (electricity)|electrical insulators]] (researched in [[ceramic engineering]]). With such a large range of possible options for the composition/structure of a ceramic (nearly all of the elements, nearly all types of bonding, and all levels of crystallinity), the breadth of the subject is vast, and identifiable attributes ([[hardness]], [[toughness]], [[electrical resistivity and conductivity|electrical conductivity]]) are difficult to specify for the group as a whole. General properties such as high melting temperature, high hardness, poor conductivity, high [[elastic modulus|moduli of elasticity]], chemical resistance, and low ductility are the norm,<ref>{{cite book |author1=Black, J. T. |author2=Kohser, R. A. |title=DeGarmo's materials and processes in manufacturing |publisher=Wiley |year=2012 |isbn=978-0-470-92467-9 |pages=226}}</ref> with known exceptions to each of these rules ([[piezoelectricity|piezoelectric ceramics]], low [[glass transition]] temperature ceramics, [[superconductivity|superconductive ceramics]]).

Composites such as [[fiberglass]] and [[carbon-fiber-reinforced polymer|carbon fiber]], while containing ceramic materials, are not considered to be part of the ceramic family.<ref>{{cite book |author1=Carter, C. B. |author2=Norton, M. G. |title=Ceramic materials: Science and engineering |publisher=Springer |year=2007 |isbn=978-0-387-46271-4 |url=https://books.google.com/books?id=aE_VQ8I24OoC&pg=PA3 |pages=3 & 4}}</ref>

Highly oriented crystalline ceramic materials are not amenable to a great range of processing. Methods for dealing with them tend to fall into one of two categories: either making the ceramic in the desired shape by reaction ''in situ'' or "forming" powders into the desired shape and then [[sintering]] to form a solid body. [[Ceramic forming techniques]] include shaping by hand (sometimes including a rotation process called "throwing"), [[slip casting]], [[tape casting]] (used for making very thin ceramic capacitors), [[injection molding]], dry pressing, and other variations.

Many ceramics experts do not consider materials with an [[amorphous]] (noncrystalline) character (i.e., glass) to be ceramics, even though glassmaking involves several steps of the ceramic process and its mechanical properties are similar to those of ceramic materials. However, heat treatments can convert glass into a semi-crystalline material known as [[glass-ceramic]].<ref>{{Cite web |url=https://www.twi-global.com/technical-knowledge/faqs/faq-how-are-glass-ceramics-and-glass-ceramics-defined.aspx|title=How are Glass, Ceramics and Glass-Ceramics Defined?|website=TWI Global |access-date=2021-10-01|archive-date=2021-10-01|archive-url=https://web.archive.org/web/20211001044001/https://www.twi-global.com/technical-knowledge/faqs/faq-how-are-glass-ceramics-and-glass-ceramics-defined|url-status=live}}</ref>

Traditional ceramic raw materials include clay minerals such as [[kaolinite]], whereas more recent materials include aluminium oxide, more commonly known as [[alumina]]. Modern ceramic materials, which are classified as advanced ceramics, include [[silicon carbide]] and [[tungsten carbide]]. Both are valued for their abrasion resistance and are therefore used in applications such as the wear plates of crushing equipment in mining operations. Advanced ceramics are also used in the medical, electrical, electronics, and armor industries.