Editing Materials science (section)

==Industry==
[[File:Drink containers.png|thumb|329x329px|Beverage containers of all three materials types: ceramic (glass), metal (aluminum), and polymer (plastic).]]
Radical [[Timeline of materials technology|materials advances]] can drive the creation of new products or even new industries, but stable industries also employ materials scientists to make incremental improvements and troubleshoot issues with currently used materials. Industrial applications of materials science include materials design, cost-benefit tradeoffs in industrial production of materials, processing methods ([[casting]], [[rolling]], [[welding]], [[ion implantation]], [[crystal growth]], [[thin-film deposition]], [[sintering]], [[glassblowing]], etc.), and analytic methods (characterization methods such as [[electron microscopy]], [[X-ray crystallography|X-ray diffraction]], [[calorimetry]], [[Microprobe|nuclear microscopy (HEFIB)]], [[Rutherford backscattering]], [[neutron diffraction]], small-angle X-ray scattering (SAXS), etc.).

Besides material characterization, the material scientist or engineer also deals with extracting materials and converting them into useful forms. Thus [[ingot]] casting, [[foundry]] methods, [[blast furnace]] extraction, and [[electrolytic process|electrolytic extraction]] are all part of the required knowledge of a materials engineer. Often the presence, absence, or variation of minute quantities of secondary elements and compounds in a bulk material will greatly affect the final properties of the materials produced. For example, steels are classified based on 1/10 and 1/100 weight percentages of the carbon and other alloying elements they contain. Thus, the extracting and purifying methods used to extract iron in a blast furnace can affect the quality of steel that is produced.

Solid materials are generally grouped into three basic classifications: ceramics, metals, and polymers. This broad classification is based on the empirical makeup and atomic structure of the solid materials, and most solids fall into one of these broad categories.<ref>{{Cite book |last1=Callister |first1=William D. |title=Materials Science and Engineering an Introduction |last2=Rethwish |first2=David G. |publisher=John Wiley and Sons |year=2018 |isbn=9780470419977 |edition=10th |location=Hoboken, NJ |pages=12 |language=English}}</ref> An item that is often made from each of these materials types is the beverage container. The material types used for beverage containers accordingly provide different advantages and disadvantages, depending on the material used. Ceramic (glass) containers are optically transparent, impervious to the passage of carbon dioxide, relatively inexpensive, and are easily recycled, but are also heavy and fracture easily. Metal (aluminum alloy) is relatively strong, is a good barrier to the diffusion of carbon dioxide, and is easily recycled. However, the cans are opaque, expensive to produce, and are easily dented and punctured. Polymers (polyethylene plastic) are relatively strong, can be optically transparent, are inexpensive and lightweight, and can be recyclable, but are not as impervious to the passage of carbon dioxide as aluminum and glass.

===Ceramics and glasses===
{{Main|Ceramic}}
[[File:Si3N4bearings.jpg|thumb|upright=0.9|Si<sub>3</sub>N<sub>4</sub> ceramic bearing parts]]
Another application of materials science is the study of [[ceramic]]s and [[glass]]es, typically the most brittle materials with industrial relevance. Many ceramics and glasses exhibit covalent or ionic-covalent bonding with SiO<sub>2</sub> ([[Silicon dioxide|silica]]) as a fundamental building block. Ceramics – not to be confused with raw, unfired [[clay]] – are usually seen in crystalline form. The vast majority of commercial glasses contain a metal oxide fused with silica. At the high temperatures used to prepare glass, the material is a viscous liquid which solidifies into a disordered state upon cooling. Windowpanes and eyeglasses are important examples. Fibers of glass are also used for long-range telecommunication and optical transmission. Scratch resistant Corning [[Gorilla Glass]] is a well-known example of the application of materials science to drastically improve the properties of common components.

Engineering ceramics are known for their stiffness and stability under high temperatures, compression and electrical stress. Alumina, [[silicon carbide]], and [[tungsten carbide]] are made from a fine powder of their constituents in a process of sintering with a binder. Hot pressing provides higher density material. Chemical vapor deposition can place a film of a ceramic on another material. Cermets are ceramic particles containing some metals. The wear resistance of tools is derived from cemented carbides with the metal phase of cobalt and nickel typically added to modify properties.

Ceramics can be significantly strengthened for engineering applications using the principle of [[Faber-Evans model|crack deflection]].<ref>{{Cite journal |last1=Faber |first1=K. T. |last2=Evans |first2=A. G. |date=1983-04-01 |title=Crack deflection processes—I. Theory |url=https://dx.doi.org/10.1016/0001-6160%2883%2990046-9 |journal=Acta Metallurgica |language=en |volume=31 |issue=4 |pages=565–576 |doi=10.1016/0001-6160(83)90046-9 |issn=0001-6160}}</ref> This process involves the strategic addition of second-phase particles within a ceramic matrix, optimizing their shape, size, and distribution to direct and control crack propagation. This approach enhances fracture toughness, paving the way for the creation of advanced, high-performance ceramics in various industries.<ref>{{Cite journal |last1=Faber |first1=K. T. |last2=Evans |first2=A. G. |date=1983-04-01 |title=Crack deflection processes—II. Experiment |url=https://dx.doi.org/10.1016/0001-6160%2883%2990047-0 |journal=Acta Metallurgica |language=en |volume=31 |issue=4 |pages=577–584 |doi=10.1016/0001-6160(83)90047-0 |issn=0001-6160}}</ref>

===Composites===
{{Main|Composite material}}
[[File:Cfaser haarrp.jpg|thumb|right|upright=0.9|A 6&nbsp;μm diameter carbon filament (running from bottom left to top right) sitting atop the much larger human hair]]
Another application of materials science in industry is making [[composite material]]s. These are structured materials composed of two or more macroscopic phases.

Applications range from structural elements such as steel-reinforced concrete, to the thermal insulating tiles, which play a key and integral role in NASA's [[Space Shuttle thermal protection system]], which is used to protect the surface of the shuttle from the heat of re-entry into the Earth's atmosphere. One example is [[reinforced Carbon-Carbon]] (RCC), the light gray material, which withstands re-entry temperatures up to {{convert|1510|C|F}} and protects the Space Shuttle's wing leading edges and nose cap.<ref>{{Cite book |last=Green |first=D. |title=MILCOM 2005 – 2005 IEEE Military Communications Conference |chapter=IPV6 BEnefits to the Warfighter |chapter-url=http://dx.doi.org/10.1109/milcom.2005.1606007 |year=2005 |pages=1–6 |publisher=IEEE |doi=10.1109/milcom.2005.1606007|isbn=0-7803-9393-7 |s2cid=31152759 }}</ref> RCC is a laminated composite material made from [[graphite]] [[rayon]] cloth and impregnated with a [[phenolic resin]]. After [[Curing (chemistry)|curing]] at high temperature in an [[autoclave]], the [[laminate]] is [[Pyrolysis|pyrolized]] to convert the resin to carbon, impregnated with [[furfuryl alcohol]] in a vacuum chamber, and cured-pyrolized to convert the furfuryl alcohol to carbon. To provide oxidation resistance for reusability, the outer layers of the RCC are converted to [[silicon carbide]].

Other examples can be seen in the "plastic" casings of television sets, cell-phones and so on. These plastic casings are usually a composite material made up of a [[thermoplastic]] matrix such as [[acrylonitrile butadiene styrene]] (ABS) in which [[calcium carbonate]] chalk, [[talc]], [[glass fiber]]s or [[carbon fiber]]s have been added for added strength, bulk, or [[Electrostatics#Static electricity and chemical industry|electrostatic dispersion]]. These additions may be termed reinforcing fibers, or dispersants, depending on their purpose.

===Polymers===
{{Main|Polymer}}
[[File:Polypropylene.svg|thumb|left|upright=0.9|The repeating unit of the polymer polypropylene]]
[[File:Expanded polystyrene foam dunnage.jpg|thumb|Expanded polystyrene polymer packaging]]
[[Polymer]]s are chemical compounds made up of a large number of identical components linked together like chains.<ref>{{Cite web |date=2017-10-13 |title=Explainer: What are polymers? |url=https://www.snexplores.org/article/explainer-what-are-polymers |access-date=2024-05-02 |language=en-US}}</ref> Polymers are the raw materials (the resins) used to make what are commonly called plastics and [[rubber]]. Plastics and rubber are the final product, created after one or more polymers or additives have been added to a resin during processing, which is then shaped into a final form. Plastics in former and in current widespread use include [[polyethylene]], [[polypropylene]], [[polyvinyl chloride]] (PVC), [[polystyrene]], [[nylon]]s, [[polyester]]s, [[acrylic resin|acrylics]], [[polyurethane]]s, and [[polycarbonate]]s. Rubbers include natural rubber, [[styrene-butadiene]] rubber, [[chloroprene]], and [[butadiene rubber]]. Plastics are generally classified as ''commodity'', ''specialty'' and [[engineering plastic|''engineering'' plastics]].

Polyvinyl chloride (PVC) is widely used, inexpensive, and annual production quantities are large. It lends itself to a vast array of applications, from [[artificial leather]] to [[electrical insulation]] and cabling, [[packaging]], and [[Food storage|containers]]. Its fabrication and processing are simple and well-established. The versatility of PVC is due to the wide range of [[plasticiser]]s and other additives that it accepts.<ref>{{Cite journal |last1=Bernard |first1=L. |last2=Cueff |first2=R. |last3=Breysse |first3=C. |last4=Décaudin |first4=B. |last5=Sautou |first5=V. |date=2015-05-15 |title=Migrability of PVC plasticizers from medical devices into a simulant of infused solutions |url=https://www.sciencedirect.com/science/article/pii/S037851731500246X |journal=International Journal of Pharmaceutics |language=en |volume=485 |issue=1 |pages=341–347 |doi=10.1016/j.ijpharm.2015.03.030 |pmid=25796128 |issn=0378-5173}}</ref> The term "additives" in polymer science refers to the chemicals and compounds added to the polymer base to modify its material properties.

[[Polycarbonate]] would be normally considered an engineering plastic (other examples include [[PEEK]], ABS). Such plastics are valued for their superior strengths and other special material properties. They are usually not used for disposable applications, unlike commodity plastics.

Specialty plastics are materials with unique characteristics, such as ultra-high strength, electrical conductivity, electro-fluorescence, high thermal stability, etc.

The dividing lines between the various types of plastics is not based on material but rather on their properties and applications. For example, [[polyethylene]] (PE) is a cheap, low friction polymer commonly used to make disposable bags for shopping and trash, and is considered a commodity plastic, whereas [[medium-density polyethylene]] (MDPE) is used for underground gas and water pipes, and another variety called [[ultra-high-molecular-weight polyethylene]] (UHMWPE) is an engineering plastic which is used extensively as the glide rails for industrial equipment and the low-friction socket in implanted [[hip joint]]s.

===Metal alloys===
{{Main|Alloy}}
[[File:Steel wire rope.png|thumb|upright|Wire rope made from [[steel]] alloy]]
The alloys of iron ([[steel]], [[stainless steel]], [[cast iron]], [[tool steel]], [[alloy steel]]s) make up the largest proportion of metals today both by quantity and commercial value.

Iron alloyed with various proportions of carbon gives [[Carbon steel#Mild or low-carbon steel|low]], mid and [[high carbon steel]]s. An iron-carbon alloy is only considered steel if the carbon level is between 0.01% and 2.00% by weight. For steels, the [[hardness]] and tensile strength of the steel is related to the amount of carbon present, with increasing carbon levels also leading to lower ductility and toughness. [[Heat treatment]] processes such as [[quenching]] and [[tempering (metallurgy)|tempering]] can significantly change these properties, however. In contrast, [[Invar|certain metal alloys]] exhibit unique properties where their size and density remain unchanged across a range of temperatures.<ref>{{Cite journal |last1=Lohaus |first1=S. H. |last2=Heine |first2=M. |last3=Guzman |first3=P. |last4=Bernal-Choban |first4=C. M. |last5=Saunders |first5=C. N. |last6=Shen |first6=G. |last7=Hellman |first7=O. |last8=Broido |first8=D. |last9=Fultz |first9=B. |date=2023-07-27 |title=A thermodynamic explanation of the Invar effect |url=https://www.nature.com/articles/s41567-023-02142-z |journal=Nature Physics |volume=19 |issue=11 |language=en |pages=1642–1648 |doi=10.1038/s41567-023-02142-z |bibcode=2023NatPh..19.1642L |osti=1993279 |s2cid=260266502 |issn=1745-2481}}</ref> Cast iron is defined as an iron–carbon alloy with more than 2.00%, but less than 6.67% carbon. Stainless steel is defined as a regular steel alloy with greater than 10% by weight alloying content of [[chromium]]. [[Nickel]] and [[molybdenum]] are typically also added in stainless steels.

Other significant metallic alloys are those of [[Aluminium alloy|aluminium]], [[Titanium alloys|titanium]], [[copper]] and [[Magnesium alloy|magnesium]]. [[Copper alloys]] have been known for a long time (since the [[Bronze Age]]), while the alloys of the other three metals have been relatively recently developed. Due to the chemical reactivity of these metals, the electrolytic extraction processes required were only developed relatively recently. The alloys of aluminium, titanium and magnesium are also known and valued for their high strength to weight ratios and, in the case of magnesium, their ability to provide electromagnetic shielding.<ref>{{Cite journal |last1=Chen |first1=Xianhua |last2=Liu |first2=Lizi |last3=Liu |first3=Juan |last4=Pan |first4=Fusheng |date=2015 |title=Microstructure, electromagnetic shielding effectiveness and mechanical properties of Mg–Zn–Y–Zr alloys |url=http://dx.doi.org/10.1016/j.matdes.2014.09.034 |journal=Materials & Design  |volume=65 |pages=360–369 |doi=10.1016/j.matdes.2014.09.034 |issn=0261-3069}}</ref> These materials are ideal for situations where high strength to weight ratios are more important than bulk cost, such as in the aerospace industry and certain automotive engineering applications.

===Semiconductors===
{{Main|Semiconductor}}
A [[semiconductor]] is a material that has a [[resistivity]] between a [[electrical conductor|conductor]] and [[Insulator (electricity)|insulator]]. Modern day electronics run on semiconductors, and the industry had an estimated US$530 billion market in 2021.<ref>{{cite web |title=Semiconductor Market Size, Share & COVID-19 Impact Analysis, By Component (Memory Devices, Logic Devices, Analog IC, MPU, Discrete Power Devices, MCU, Sensors, and Others), By Application (Networking & Communications, Data Processing, Industrial, Consumer Electronics, Automotive, and Government), and Regional Forecast, 2022–2029 |url=https://www.fortunebusinessinsights.com/semiconductor-market-102365 |website=Fortune Business Insights |access-date=16 July 2023 |url-status=live |archive-url=https://web.archive.org/web/20230611212323/https://www.fortunebusinessinsights.com/semiconductor-market-102365 |archive-date=11 June 2023 | date=16 July 2023}}</ref> Its electronic properties can be greatly altered through intentionally introducing impurities in a process referred to as doping. Semiconductor materials are used to build [[diode]]s, [[transistor]]s, [[light-emitting diode]]s (LEDs), and analog and digital [[electric circuit]]s, among their many uses. Semiconductor devices have replaced [[thermionic converter|thermionic]] devices like vacuum tubes in most applications. Semiconductor devices are manufactured both as single discrete devices and as [[integrated circuit]]s (ICs), which consist of a number—from a few to millions—of devices manufactured and interconnected on a single semiconductor [[Substrate (materials science)|substrate]].<ref>{{cite web |url=https://www.aip.org/jobs/profiles/semiconductor-industry-careers |title=Semiconductor Industry Careers |access-date=2016-05-15 |url-status=live |archive-url=https://web.archive.org/web/20160604150127/https://www.aip.org/jobs/profiles/semiconductor-industry-careers |archive-date=2016-06-04 |date=2013-09-06 }}</ref>

Of all the semiconductors in use today, [[silicon]] makes up the largest portion both by quantity and commercial value. Monocrystalline silicon is used to produce wafers used in the semiconductor and [[electronics industry]]. [[Gallium arsenide]] (GaAs) is the second most popular semiconductor used. Due to its higher [[electron mobility]] and [[saturation velocity]] compared to silicon, it is a material of choice for high-speed electronics applications. These superior properties are compelling reasons to use GaAs circuitry in mobile phones, satellite communications, microwave point-to-point links and higher frequency radar systems. Other semiconductor materials include [[germanium]], [[silicon carbide]], and [[gallium nitride]] and have various applications.