Ceramic

A ceramic is any of the various hard,

.

The earliest ceramics made by humans were brick walls used for building houses and other structures, while

.

The word ceramic comes from the Ancient Greek word κεραμικός (keramikós), meaning "of or for pottery"^[4] (from κέραμος (kéramos) 'potter's clay, tile, pottery').^[5] The earliest known mention of the root ceram- is the Mycenaean Greek ke-ra-me-we, workers of ceramic, written in Linear B syllabic script.^[6] The word ceramic can 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.^[7]

Materials

Ceramic material is an inorganic, metallic 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 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 °C to 1,600 °C (1,800 °F to 3,000 °F).

The crystallinity of ceramic materials varies widely. Most often, fired ceramics are either 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 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 conductivity) are difficult to specify for the group as a whole. General properties such as high melting temperature, high hardness, poor conductivity, high moduli of elasticity, chemical resistance, and low ductility are the norm,^[8] with known exceptions to each of these rules (piezoelectric ceramics, glass transition temperature, superconductive ceramics).

Composites such as

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

injection molding

, dry pressing, and other variations.

Many ceramics experts do not consider materials with an

Traditional ceramic raw materials include clay minerals such as

. 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.

History

Human beings appear to have been making their own ceramics for at least 26,000 years, subjecting clay and silica to intense heat to fuse and form ceramic materials. The earliest found so far were in southern central Europe and were sculpted figures, not dishes.^[12] The earliest known pottery was made by mixing animal products with clay and firing it at up to 800 °C (1,500 °F). While pottery fragments have been found up to 19,000 years old, it was not until about 10,000 years later that regular pottery became common. An early people that spread across much of Europe is named after its use of pottery: the Corded Ware culture. These early Indo-European peoples decorated their pottery by wrapping it with rope while it was still wet. When the ceramics were fired, the rope burned off but left a decorative pattern of complex grooves on the surface.

The invention of the wheel eventually led to the production of smoother, more even pottery using the wheel-forming (throwing) technique, like the

techniques, which involved coating pottery with silicon, bone ash, or other materials that could melt and reform into a glassy surface, making a vessel less pervious to water.

Archaeology

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

sherds

. The processing of collected sherds can be consistent with two main types of analysis: technical and traditional.

The 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 the technological state of the people, among other conclusions. Besides, by looking at stylistic changes in ceramics over time, it is 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.[13]

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: the temper is a material added to the clay during the initial production stage and 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 tempered 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. Based on the source assignment of the artifact, further investigations can be made into the site of manufacture.

Properties

The physical properties of any ceramic substance are a direct result of its crystalline structure and chemical composition.

.

to tens of micrometers (µm). This is typically somewhere between the minimum wavelength of visible light and the resolution limit of the naked eye.

The microstructure includes most grains, secondary phases, grain boundaries, pores, micro-cracks, structural defects, and hardness micro indentions. Most bulk mechanical, optical, thermal, electrical, and magnetic properties are significantly affected by the observed microstructure. The fabrication method and process conditions are generally indicated by the microstructure. The root cause of many ceramic failures is evident in the cleaved and polished microstructure. Physical properties which constitute the field of materials science and engineering include the following:

Mechanical properties

Mechanical properties are important in structural and building materials as well as textile fabrics. In modern

predictions with real-life failures.

Ceramic materials are usually

failure modes

of metals.

These materials do show plastic deformation. However, because of the rigid structure of crystalline material, there are very few available slip systems for dislocations to move, and so they deform very slowly.

To overcome the brittle behavior, ceramic material development has introduced the class of ceramic matrix composite materials, in which ceramic fibers are embedded and with specific coatings are forming fiber bridges across any crack. This mechanism substantially increases the fracture toughness of such ceramics. Ceramic disc brakes are an example of using a ceramic matrix composite material manufactured with a specific process.

Scientists are working on developing ceramic materials that can withstand significant deformation without breaking. A first such material that can deform in room temperature was found in 2024.^[14]

Ice-templating for enhanced mechanical properties

If a ceramic is subjected to substantial mechanical loading, it can undergo a process called ice-templating, which allows some control of the microstructure of the ceramic product and therefore some control of the mechanical properties. Ceramic engineers use this technique to tune the mechanical properties to their desired application. Specifically, the strength is increased when this technique is employed. Ice templating allows the creation of macroscopic pores in a unidirectional arrangement. The applications of this oxide strengthening technique are important for solid oxide fuel cells and water filtration devices.^[15]

To process a sample through ice templating, an aqueous

]

During ice-templating, a few variables can be controlled to influence the pore size and morphology of the microstructure. These important variables are the initial solids loading of the colloid, the cooling rate, the sintering temperature and duration, and the use of certain additives which can influence the microstructural morphology during the process. A good understanding of these parameters is essential to understanding the relationships between processing, microstructure, and mechanical properties of anisotropically porous materials.[16]

Electrical properties

Semiconductors

Some ceramics are

. When various gases are passed over a polycrystalline ceramic, its electrical resistance changes. With tuning to the possible gas mixtures, very inexpensive devices can be produced.

Superconductivity

Under some conditions, such as extremely low temperatures, some ceramics exhibit high-temperature superconductivity. ^{[clarification needed]} The reason for this is not understood, but there are two major families of superconducting ceramics.

Ferroelectricity and supersets

Piezoelectricity, a link between electrical and mechanical response, is exhibited by a large number of ceramic materials, including the quartz used to measure time in watches and other electronics. Such devices use both properties of piezoelectrics, using electricity to produce a mechanical motion (powering the device) and then using this mechanical motion to produce electricity (generating a signal). The unit of time measured is the natural interval required for electricity to be converted into mechanical energy and back again.

The piezoelectric effect is generally stronger in materials that also exhibit

, where the tiny rise in temperature from a warm body entering the room is enough to produce a measurable voltage in the crystal.

In turn, pyroelectricity is seen most strongly in materials that also display the

.

The most common such materials are

.

Positive thermal coefficient

Temperature increases can cause grain boundaries to suddenly become insulating in some semiconducting ceramic materials, mostly mixtures of heavy metal titanates. The critical transition temperature can be adjusted over a wide range by variations in chemistry. In such materials, current will pass through the material until joule heating brings it to the transition temperature, at which point the circuit will be broken and current flow will cease. Such ceramics are used as self-controlled heating elements in, for example, the rear-window defrost circuits of automobiles.

At the transition temperature, the material's dielectric response becomes theoretically infinite. While a lack of temperature control would rule out any practical use of the material near its critical temperature, the dielectric effect remains exceptionally strong even at much higher temperatures. Titanates with critical temperatures far below room temperature have become synonymous with "ceramic" in the context of ceramic capacitors for just this reason.

Optical properties

synthetic sapphire

output window

.

Thus, there is an increasing need in the

and pods, as well as protection against improvised explosive devices (IED).

In the 1960s, scientists at

scanners. Other ceramic materials, generally requiring greater purity in their make-up than those above, include forms of several chemical compounds, including:

1. Barium titanate: (often mixed with strontium titanate) displays ferroelectricity, meaning that its mechanical, electrical, and thermal responses are c
2. Sialon (silicon aluminium oxynitride) has high strength; resistance to thermal shock, chemical and wear resistance, and low density. These ceramics are used in non-ferrous molten metal handling, weld pins, and the chemical industry.
3. Silicon carbide (SiC) is used as a susceptor in microwave furnaces, a commonly used abrasive, and as a refractory material.
4. Silicon nitride (Si₃N₄) is used as an abrasive powder.
5. electrical insulator
   .
6. Titanium carbide Used in space shuttle re-entry shields and scratchproof watches.
7. Uranium oxide (UO₂), used as fuel in nuclear reactors.
8. high-temperature superconductor
   .
9. Zinc oxide (ZnO), which is a semiconductor, and used in the construction of varistors.
10. metastable structures can impart transformation toughening for mechanical applications; most ceramic knife blades are made of this material. Partially stabilised zirconia (PSZ) is much less brittle than other ceramics and is used for metal forming tools, valves and liners, abrasive slurries, kitchen knives and bearings subject to severe abrasion.^[17]

Products

By usage

For convenience, ceramic products are usually divided into four main types; these are shown below with some examples:[18]

1. Structural, including
   roof tiles
2. Refractories, such as kiln linings, gas fire radiants, steel and glass making crucibles
3. Whitewares, including tableware, cookware, wall tiles, pottery products and sanitary ware^[19]
4. Technical, also known as engineering, advanced, special, and fine ceramics. Such items include:
   • gas burner nozzles
   • vehicle armor
   • nuclear fuel uranium oxide pellets
   • biomedical implants
   • coatings of jet engine turbine blades
   • ceramic matrix composite gas turbine parts
   • reinforced carbon–carbon ceramic disc brakes
   • missile nose cones
   • bearings
   • tiles used in the Space Shuttle program

Ceramics made with clay

Frequently, the raw materials of modern ceramics do not include clays.^[20] Those that do have been classified as:

1. Earthenware, fired at lower temperatures than other types
2. Stoneware, vitreous or semi-vitreous
3. kaolin
4. Bone china

Classification

Ceramics can also be classified into three distinct material categories:

1. zirconia
2. Non-oxides: carbide, boride, nitride, silicide
3. Composite materials: particulate reinforced, fiber reinforced, combinations of oxides and nonoxides.

Each one of these classes can be developed into unique material properties.

Applications

1. Knife blades: the blade of a ceramic knife will stay sharp for much longer than that of a steel knife, although it is more brittle and susceptible to breakage.
2. Carbon-ceramic brake disks for vehicles: highly resistant to brake fade
   at high temperatures.
3. Advanced
   Armoured fighting vehicles because they offer superior penetrating resistance against shaped charge (HEAT rounds) and kinetic energy penetrators
   .
4. Ceramics such as
   cockpits
   of some military aircraft.
5. Ceramic ball bearings can be used in place of steel. Their greater hardness results in lower susceptibility to wear. Ceramic bearings typically last triple the lifetime of steel bearings. They deform less than steel under load, resulting in less contact with the bearing retainer walls and lower friction. In very high-speed applications, heat from friction causes more problems for metal bearings than ceramic bearings. Ceramics are chemically resistant to corrosion and are preferred for environments where steel bearings would rust. In some applications their electricity-insulating properties are advantageous. Drawbacks to ceramic bearings include significantly higher cost, susceptibility to damage under shock loads, and the potential to wear steel parts due to ceramics' greater hardness.
6. In the early 1980s
   thermal insulator. Thus, despite the desirable properties of ceramics, prohibitive production costs and limited advantages have prevented widespread ceramic engine component adoption. In addition, small imperfections in ceramic material along with low fracture toughness can lead to cracking and potentially dangerous equipment failure. Such engines are possible experimentally, but mass production is not feasible with current technology. ^{[citation needed}
   ]
7. Experiments with ceramic parts for gas turbine engines are being conducted. Currently, even blades made of advanced metal alloys used in the engines' hot section require cooling and careful monitoring of operating temperatures. Turbine engines made with ceramics could operate more efficiently, providing for greater range and payload.
8. Recent advances have been made in ceramics which include bioceramics such as dental implants and synthetic bones. Hydroxyapatite, the major mineral component of bone, has been made synthetically from several biological and chemical components 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 reaction. They are of great interest for gene delivery and tissue engineering scaffolding. Most hydroxyapatite ceramics are quite porous and lack mechanical strength and are therefore used solely 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 inflammation and increase the 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 replacement, or with the incorporation of protein collagens, the manufacture of synthetic bones.
9. Applications for actinide-containing ceramic materials include nuclear fuels for burning excess plutonium (Pu), or a chemically-inert source of alpha radiation in power supplies for uncrewed space vehicles or microelectronic devices. Use and disposal of radioactive actinides require immobilization in a durable host material. Long half-life radionuclides such as actinide are immobilized using chemically-durable crystalline materials based on polycrystalline ceramics and large single crystals.^[21]
10. High-tech ceramics are used for producing watch cases. The material is valued by watchmakers for its light weight, scratch resistance, durability, and smooth touch.
    IWC is one of the brands that pioneered the use of ceramic in watchmaking.^[22]

See also

• Ceramic chemistry – chemistry of ceramic glazePages displaying wikidata descriptions as a fallback
• Ceramic engineering – Science and technology of creating objects from inorganic, non-metallic materials
• Ceramic nanoparticle
• Ceramic matrix composite – Composite material consisting of ceramic fibers in a ceramic matrix
• Ceramic art – Decorative objects made from clay and other raw materials by the process of pottery
• Pottery fracture – Result of thermal treatment on ceramic

References

1. ISBN 9783527630189. Archived
   from the original on 10 December 2020. Retrieved 30 October 2020.
2. ^ "ceramic". The Free Dictionary. Archived from the original on 2020-08-03. Retrieved 2020-08-03.
3. ISBN 978-0-387-46271-4
   .
4. Perseus Project
5. Perseus Project
6. ^ "keramewe". Palaeolexicon. Archived from the original on 2011-05-01.
7. ^ "ceramic". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
8. ISBN 978-0-470-92467-9
   .
9. ISBN 978-0-387-46271-4
   .
10. ^ "How are Glass, Ceramics and Glass-Ceramics Defined?". TWI Global. Archived from the original on 2021-10-01. Retrieved 2021-10-01.
11. ^ "Ceramics and Glass - an overview". ScienceDirect Topics. Archived from the original on 2021-08-09. Retrieved 2021-08-09.^{[not specific enough to verify]}
12. ^ "Ceramic history". Materials Science and Engineering Education. University of Washington Departments. Archived from the original on 2020-11-06. Retrieved 2020-03-02.
13. ^ "Ceramic Analysis". The Process of Archaeology. Mississippi Valley Archaeological Center. Archived from the original on June 3, 2012. Retrieved 2004-11-12.
14. doi:10.1038/d41586-024-00443-8
    .
15. S2CID 115752128 – via ResearchGate
    .
16. PMID 27075397
    .
17. S2CID 4189416
    .
18. ^ 'Whitewares: Production, Testing And Quality Control.' W. Ryan, C. Radford. Pergamon Press, 1987.
19. ^ "Whiteware Pottery". Encyclopædia Britannica. Archived from the original on 9 July 2015. Retrieved 30 June 2015.
20. ^ Geiger, Greg. Introduction To Ceramics, American Ceramic Society
21. ISBN 978-1-84816-418-5. Archived from the original on 2021-10-01. Retrieved 2017-08-31.^{[page needed}
    ]
22. ^ "Watch Case Materials Explained: Ceramic". aBlogtoWatch. 18 April 2012. Archived from the original on 8 March 2017. Retrieved 8 March 2017.

Further reading

• Guy, John (1986). Guy, John (ed.). Oriental trade ceramics in South-East Asia, ninth to sixteenth centuries: with a catalogue of Chinese, Vietnamese and Thai wares in Australian collections (illustrated, revised ed.). Oxford University Press.
  ISBN 9780195825930
  . Retrieved 24 April 2014.

External links

• Ceramics Science and Technology