From Wikipedia, the free encyclopedia
porcelain vase dated to
insulated with
insulation.
Mid-16th century ceramic tilework on the ,
Spherical Hanging Ornament, ,
Fixed partial porcelain , or "bridge"
A ceramic is an , nonmetallic
comprising ,
atoms primarily held in
bonds. The
of ceramic materials ranges from highly oriented to semi-crystalline, and often completely
(e.g., ). Varying crystallinity and
consumption in the ionic and covalent bonds cause most ceramic materials to be good thermal and
and extensively researched in . Nevertheless, with such a large range of possible options for the composition/structure of a ceramic (e.g. 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 (e.g. , , , etc.) are hard to specify for the group as a whole. However, generalities such as high melting temperature, high hardness, poor conductivity, high , chemical resistance and low ductility are the norm, with known exceptions to each of these rules (e.g. ,
temperature, , etc.). Many composites, such as
and , while containing ceramic materials, are not considered to be part of the ceramic family.
The word "ceramic" comes from the
word κεραμικ?? (keramikos), "of pottery" or "for pottery", from κ?ραμο? (keramos), "potter's clay, tile, pottery". The earliest known mention of the root "ceram-" is the
ke-ra-me-we, "workers of ceramics", written in
syllabic script. The word "ceramic" may be used as an adjective to describe a material, product or process, or it may be used as a noun, either singular, or, more commonly, as the plural noun "ceramics".
The earliest ceramics made by humans were
objects, including
, made from , either by itself or mixed with other materials like , hardened, , in fire. Later ceramics were
and fired to create smooth, colored surfaces, decreasing
through the use of glassy, amorphous ceramic coatings on top of the crystalline ceramic substrates. Ceramics now include domestic, industrial and building products, as well as a wide range of . In the 20th century, new
were developed for use in advanced ceramic engineering, such as in .
For convenience, ceramic products are usually divid these are shown below with some examples:
Structural, including , ,
linings, gas fire radiants,
and glass making crucibles
White wares, including , cookware, wall tiles, pottery products and sanitary ware
Technical, also known as engineering, advanced, special, and fine ceramics. Such items include:
tiles used in the ,
gas burner ,
uranium oxide pellets,
coatings of
nose cones,
Frequently, the raw materials do not include clays.
Main article:
, which is often made from clay,
, which is often made from
Technical ceramics can also be classified into three distinct material categories:
Nonoxides: , , ,
: particulate reinforced, , combinations of
and nonoxides.
Each one of these classes can develop unique material properties because ceramics tend to be crystalline.
Knife blades: the blade of a
will stay sharp for much longer than that of a steel knife, although it is more brittle and can snap from a fall onto a hard surface.
for vehicles are resistant to abrasion at high temperatures.
have been designed for most modern
because they offer superior penetrating resistance against
rounds) and .
Ceramics such as
have been used in
to repel large-caliber
fire. Such plates are known commonly as , or SAPIs. Similar material is used to protect the
of some military airplanes, because of the low weight of the material.
Ceramics can be used in place of steel for . Their higher hardness means they are much less susceptible to wear and typically last for triple the lifetime of a steel part. They also deform less under load, meaning they have less contact with the bearing retainer walls and can roll faster. In very high speed applications, heat from
during rolling can cause problems for metal bearings, which are reduced by the use of ceramics. Ceramics are also more chemically resistant and can be used in wet environments where steel bearings would rust. In some cases, their electricity-insulating properties may also be valuable in bearings. Two drawbacks to ceramic bearings are a significantly higher cost and susceptibility to damage under shock loads.
In the early 1980s,
researched production of an
using ceramic components in the hot gas area. The ceramics would have allowed temperatures of over ;°F (;°C). The expected advantages would have been lighter materials and a smaller cooling system (or no need for one at all), leading to a major weight reduction. The expected increase of
of the engine (caused by the higher temperature, as shown by
theorem) could not be ver it was found that the heat transfer on the hot ceramic cylinder walls was higher than the transfer to a cooler metal wall as the cooler gas film on the metal surface works as a . Thus, despite all of these desirable properties, such engines have not succeeded in production because of costs for the ceramic components and the limited advantages. (Small imperfections in the ceramic material with its low
lead to cracks, which can lead to potentially dangerous equipment failure.) Such engines are possible in laboratory settings, but mass production is not feasible with current technology.[]
Work is being done in developing ceramic parts for
. Currently, even blades made of
used in the engines' hot section require cooling and careful limiting of operating temperatures. Turbine engines made with ceramics could operate more efficiently, giving aircraft greater range and payload for a set amount of fuel.
Recent advances have been made in ceramics which include bioceramics, such as dental implants and synthetic bones. , the natural mineral component of bone, has been made synthetically from a number of biological and chemical sources and can be formed into ceramic materials. Orthopedic implants coated with these materials bond readily to bone and other tissues in the body without rejection or inflammatory reactions so are of great interest for gene delivery and
scaffolds. Most hydroxyapatite ceramics are very porous and lack mechanical strength, and are used to coat metal orthopedic devices to aid in forming a bond to bone or as bone fillers. They are also used as fillers for orthopedic plastic screws to aid in reducing the inflammation and increase absorption of these plastic materials. Work is being done to make strong, fully dense nanocrystalline hydroxyapatite ceramic materials for orthopedic weight bearing devices, replacing foreign metal and plastic orthopedic materials with a synthetic, but naturally occurring, bone mineral. Ultimately, these ceramic materials may be used as bone replacements or with the incorporation of protein , synthetic bones.
High-tech ceramic is used in watchmaking for producing watch cases. The material is valued by watchmakers for its light weight, scratch resistance, durability and smooth touch.
is one of the brands that initiated the use of ceramic in watchmaking. The case of the IWC 2007 Top Gun edition of the Pilot's Watch
is crafted in black ceramic.
Main article:
A low magnification
of an advanced ceramic material. The properties of ceramics make fracturing an important inspection method.
A ceramic material is an inorganic, non-metallic, often crystalline oxide, nitride or carbide material. Some elements, such as
or , may be considered ceramics. Ceramic materials are brittle, hard, strong in compression, weak in
and tension. They withstand chemical erosion that occurs in other materials subjected to acidic or caustic environments. Ceramics generally can withstand very high temperatures, such as temperatures that range from 1,000 °C to 1,600 °C (1,800 °F to 3,000 °F). A
is often not understood as a ceramic because of its
(noncrystalline) character. However, glassmaking involves several steps of the ceramic process and its mechanical properties are similar to ceramic materials.
Traditional ceramic raw materials include clay minerals such as , whereas more recent materials include aluminium oxide, more commonly known as . The modern ceramic materials, which are classified as advanced ceramics, include
and . Both are valued for their abrasion resistance, and hence find use in applications such as the wear plates of crushing equipment in mining operations. Advanced ceramics are also used in the medicine, electrical and electronics industries.
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 make the ceramic in the desired shape, by reaction in situ, or by "forming" powders into the desired shape, and then
to form a solid body.
include shaping by hand (sometimes including a rotation process called "throwing"), ,
(used for making very thin ceramic capacitors, e.g.), , dry pressing, and other variations. Details of these processes are described in the two books listed below.[] A few methods use a hybrid between the two approaches.
Noncrystalline ceramics, being glass, tend to be formed from melts. The glass is shaped when either fully molten, by casting, or when in a state of toffee-like viscosity, by methods such as blowing into a mold. If later heat treatments cause this glass to become partly crystalline, the resulting material is known as a glass-ceramic, widely used as cook-top and also as a glass composite material for nuclear waste disposal.
Ceramic artifacts have an important role in archaeology for understanding the culture, technology and behavior of peoples of the past. They are among the most common artifacts to be found at an archaeological site, generally in the form of small fragments of broken pottery called . Processing of collected sherds can be consistent with two main types of analysis: technical and traditional.
Traditional analysis involves sorting ceramic artifacts, sherds and larger fragments into specific types based on style, composition, manufacturing and morphology. By creating these typologies it is possible to distinguish between different cultural styles, the purpose of the ceramic and technological state of the people among other conclusions. In addition, by looking at stylistic changes of ceramics over time is it possible to separate (seriate) the ceramics into distinct diagnostic groups (assemblages). A comparison of ceramic artifacts with known dated assemblages allows for a chronological assignment of these pieces.
The technical approach to ceramic analysis involves a finer examination of the composition of ceramic artifacts and sherds to determine the source of the material and through this the possible manufacturing site. Key criteria are the composition of the clay and the temper used in the manufacture of the article under study: temper is a material added to the clay during the initial production stage, and it is used to aid the subsequent drying process. Types of temper include shell pieces, granite fragments and ground sherd pieces called 'grog'. Temper is usually identified by microscopic examination of the temper material. Clay identification is determined by a process of refiring the ceramic, and assigning a color to it using Munsell Soil Color notation. By estimating both the clay and temper compositions, and locating a region where both are known to occur, an assignment of the material source can be made. From the source assignment of the artifact further investigations can be made into the site of manufacture.
Black, J. T. & Kohser, R. A. (2012). DeGarmo's materials and processes in manufacturing. Wiley. p. 226.  .
Carter, C. B. & Norton, M. G. (2007). Ceramic materials: Science and engineering. Springer. pp. 3 & 4.  .
, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library
, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library
, Word study tool of ancient languages
(3rd ed.). Oxford University Press. September 2005.
Carter, C. B. & Norton, M. G. (2007). Ceramic materials: Science and engineering. Springer. pp. 20 & 21.  .
Greg Geiger , American Ceramic Society
(). Retrieved on .
Mississippi Valley Archaeological Center, , Retrieved 04-11-12
Guy, John (1986). Guy, John, ed.
(illustrated, revised ed.). Oxford University Press 2014.
Wikimedia Commons has media related to .
- Oldest known Ceramic statuette of a nude female figure dated to 29 000 – 25 000 BP (Gravettian industry. Czech Republic
Click on Quick Links in the right-hand column to view examples.
– The only museum in Canada entirely devoted to ceramics
– The Evolution, Classification, Properties, Production, Firing, Finishing and Design of Advanced Ceramics
– The European Ceramic Industry Association
: Hidden categories:0.40k/s请问这是什么意思，手机无缘无故出现这个标志是什么？？？急急_百度知道
0.40k/s请问这是什么意思，手机无缘无故出现这个标志是什么？？？急急
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按默认排序
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手机网络速度
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是这样的吗
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