metallurgy
American Heritage Dictionary:
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met·al·lur·gy
(mĕt'l-ûr'jē) 
n.
metallurgically met'al·lur'gi·cal·ly adv.
metallurgist met'al·lur'gist n.
n.
- The science that deals with procedures used in extracting metals from their ores, purifying and alloying metals, and creating useful objects from metals.
- The study of metals and their properties in bulk and at the atomic level.
[New Latin metallūrgia, from Greek metallourgos, miner, worker in metals : metallon, a mine, metal + -ourgos, -worker (from ergon, work).]
metallurgic met'al·lur'gic or met'al·lur'gi·cal adj.metallurgically met'al·lur'gi·cal·ly adv.
metallurgist met'al·lur'gist n.
Fowler's Modern English Usage:
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metallurgy
the science of metals, is pronounced with the stress on the second syllable in British English, and with the stress on the first syllable in American English.
| metal, mettle, meta-, merit | |
| metaphor and simile, metathesis, meter |
Britannica Concise Encyclopedia:
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metallurgy
Art and science of extracting metals from their ores and modifying the metals for use. Metallurgy usually refers to commercial rather than laboratory methods. It also concerns the chemical, physical, and atomic properties and structures of metals and the principles by which metals are combined to form alloys. Metals are extracted from crude ore in two phases: mineral processing (also known as ore dressing) and process metallurgy. In mineral processing, the ore is broken down to isolate the desired metallic elements from the crude ore. In process metallurgy, the resulting minerals are reduced to metal, alloyed, and made available for use. blast furnace; powder metallurgy; smelting.
For more information on metallurgy, visit Britannica.com.
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The technology and science of metallic materials. Metallurgy as a branch of engineering is concerned with the production of metals and alloys, their adaptation to use, and their performance in service. As a science, metallurgy is concerned with the chemical reactions involved in the processes by which metals are produced and the chemical, physical, and mechanical behavior of metallic materials.
The field of metallurgy may be divided into process metallurgy (production metallurgy, extractive metallurgy) and physical metallurgy. In this system metal processing is considered to be a part of process metallurgy and the mechanical behavior of metals a part of physical metallurgy.
Process metallurgy, the science and technology used in the production of metals, employs some of the same unit operations and unit processes as chemical engineering. These operations and processes are carried out with ores, concentrates, scrap metals, fuels, fluxes, slags, solvents, and electrolytes. Different metals require different combinations of operations and processes, but typically the production of a metal involves two major steps. The first is the production of an impure metal from ore minerals, commonly oxides or sulfides, and the second is the refining of the reduced impure metal, for example, by selective oxidation of impurities or by electrolysis. See also Electrometallurgy; Hydrometallurgy; Iron metallurgy; Ore dressing; Pyrometallurgy; Steel manufacture.
Physical metallurgy investigates the effects of composition and treatment on the structure of metals and the relations of the structure to the properties of metals. Physical metallurgy is also concerned with the engineering applications of scientific principles to the fabrication, mechanical treatment, heat treatment, and service behavior of metals. See also Alloy; Heat treatment (metallurgy).
The structure of metals consists of their crystal structure, which is investigated by x-ray,electron, and neutron diffraction, their microstructure, which is the subject of metallography, and their macrostructure. Crystal imperfections, which provide mechanisms for processes occurring in solid metals, are investigated by x-ray diffraction and metallographic methods, especially electron microscopy. The microstructure is determined by the constituent phases and the geometrical arrangement of the microcrystals (grains) formed by those phases. Macrostructure is important in industrial metals. It involves chemical and physical inhomogeneities on a scale larger than microscopic. Examples are flow lines in steel forgings and blowholes in castings. See also Metallography; X-ray diffraction.
Phase transformations occurring in the solid state underlie many heat-treatment operations. The thermodynamics and kinetics of these transformations are a major concern of physical metallurgy. Physical metallurgy also investigates changes in the structure and properties resulting from mechanical working of metals.
For more information on metallurgy and some associated techniques see articles on individual metals and their metallurgy. See also Electroplating of metals; Metal coatings; Metal forming.
Oxford Dictionary of Archaeology:
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metallurgy
[De]
Metalworking in all its aspects; the art of working metals.
Columbia Encyclopedia:
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metallurgy
metallurgy (mĕt'əlûr'jē), science and technology of metals and their alloys. Modern metallurgical research is concerned with the preparation of radioactive metals, with obtaining metals economically from low-grade ores, with obtaining and refining rare metals hitherto not used, and with the formulation of alloys. Powder metallurgy deals with the manufacture of ferrous and nonferrous parts by compacting elemental metal or alloy powders in a die. The resultant shapes are then heated in a controlled-atmosphere furnace to bond the particles so that the part will retain the shape at normal temperatures and pressures. Welding and soldering (see solder) are techniques for joining metals metallurgically. Extractive metallurgy is the study and practice of separating metals from their ores and refining them to produce a pure metal. This article discusses the extraction of metals in general terms, but methods for the treatment of ores are quite diverse; see also aluminum, copper, gold, iron, lead, nickel, silver, tin, and zinc for special procedures followed.
Concentration of the Ore
When an ore has a low percentage of the desired metal, a method of physical concentration must be used before the extraction process begins. In one such method, the ore is crushed and placed in a machine where, by shaking, the heavier particles containing the metal are separated from the lighter rock particles by gravity. Another method is the flotation process, used commonly for copper sulfide ores. In certain cases (as when gold, silver, or occasionally copper occur "free," i.e., uncombined chemically in sand or rock), mechanical or ore dressing methods alone are sufficient to obtain relatively pure metal. Waste material is washed away or separated by screening and gravity; the concentrated ore is then treated by various chemical processes.
Separation of the Metal
Processes for separating the metal from the impurities it is found with or the other elements with which it is combined depend upon the chemical nature of the ore to be treated and upon the properties of the metal to be extracted. Gold and silver are often removed from the impurities associated with them by treatment with mercury, in which they are soluble. Another method for the separation of gold and silver is the so-called cyanide process. The Parkes process, which is based on silver being soluble in molten zinc while lead is not, is used to free silver from lead ores. Since almost all the metals are found combined with other elements in nature, chemical reactions are required to set them free. These chemical processes are classified as pyrometallurgy, electrometallurgy, and hydrometallurgy.
Pyrometallurgy, or the use of heat for the treatment of an ore, includes smelting and roasting. If the ore is an oxide, it is heated with a reducing agent, such as carbon in the form of coke or coal; the oxygen of the ore combines with the carbon and is removed in carbon dioxide, a gas (see oxidation and reduction). The waste material in the ore is called gangue; it is removed by means of a substance called a flux which, when heated, combines with it to form a molten mass called slag. Being lighter than the metal, the slag floats on it and can be skimmed or drawn off. The flux used depends upon the chemical nature of the ore; limestone is usually employed with a siliceous gangue. A sulfide ore is commonly roasted, i.e., heated in air. The metal of the ore combines with oxygen of the air to form an oxide, and the sulfur of the ore also combines with oxygen to form sulfur dioxide, which, being a gas, passes off. The metallic oxide is then treated with a reducing agent. When a carbonate ore is heated, the oxide of the metal is formed, and carbon dioxide is given off; the oxide is then reduced.
Electrometallurgy includes the preparation of certain active metals, such as aluminum, calcium, barium, magnesium, potassium, and sodium, by electrolysis: a fused compound of the metal, commonly the chloride, is subjected to an electric current, the metal collecting at the cathode.
Hydrometallurgy, sometimes called leaching, involves the selective dissolution of metals from their ores. For example, certain copper oxide and carbonate ores are treated with dilute sulfuric acid, forming water-soluble copper sulfate. The metal is recovered by electrolysis of the solution. If the metal obtained from the ore still contains impurities, special refining processes are required.
Bibliography
See R. E. Reed-Hill et al., Physical Metallurgy Principles (1991); H. Chandler, Metallurgy for the Non-Metallurgist (1998); D. A. Brandt et al., Metallurgy Fundamentals (1999).
Word Tutor:
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metallurgic
IN BRIEF: adj. - Of or relating to a science of extracting certain substances from ore..
Paraguay's metallurgic industry has been negatively affected by the lack of scrap it uses as raw material
— Business News Americas
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Mosby's Dental Dictionary:
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metallurgy
n
The study of metals and their properties, including separating metals from their ores, the making and compounding of alloys, and the technology and science of working and heat-treating metals to alter their physical characteristics.
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categories related to 'metallurgist'
Wikipedia on Answers.com:
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Metallurgy
Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys. It is also the technology of metals: the way in which science is applied to their practical use. Metallurgy is distinguished from the craft of metalworking.
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Contents
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Etymology and pronunciation
The word was originally (1593) an alchemist's term for the extraction of metals from minerals: the ending -urgy signifying a process, especially manufacturing: it was in this sense it was used by the 1797 Encyclopaedia Britannica.[1] In the late 19th century it was extended to the more general scientific study of metals and alloys and related processes.[1] The roots are borrowed from Ancient Greek: μεταλλουργός, matallourgos, "worker in metal", from μέταλλον, metallon, "metal" + ἔργον, ergon, "work". In English, the /meˈtælədʒi/ pronunciation is the more common one in the UK and Commonwealth. The /ˈmetələrdʒi/ pronunciation is the more common one in the USA, and is the first-listed variant in various American dictionaries (e.g., Merriam-Webster Collegiate, American Heritage).
History
See also: History of ferrous metallurgy, Chalcolithic, Bronze Age, Iron Age, Metallurgy in Pre-Columbian America, Metallurgy in pre-Columbian Mesoamerica, and History of metallurgy in the Indian subcontinent
The first evidence of human metallurgy dates from the 5th and 6th millennium BC, and was found in the archaeological sites of Majdanpek, Yarmovac and Plocnik all three in Serbia. To date, the earliest copper smelting is found at the Belovode site,[2] these examples include a copper axe from 5500 BC belonging to the Vinča culture.[3] Other signs of human metallurgy are found from the third millennium BC in places like Palmela (Portugal), Cortes de Navarra (Spain), and Stonehenge (United Kingdom). However, as often happens with the study of prehistoric times, the ultimate beginnings cannot be clearly defined and new discoveries are continuous and ongoing.
Silver, copper, tin and meteoric iron can also be found native, allowing a limited amount of metalworking in early cultures. Egyptian weapons made from meteoric iron in about 3000 BC were highly prized as "Daggers from Heaven".[4] However, by learning to get copper and tin by heating rocks and combining those two metals to make an alloy called bronze, the technology of metallurgy began about 3500 BC with the Bronze Age.
The extraction of iron from its ore into a workable metal is much more difficult. It appears to have been invented by the Hittites in about 1200 BC, beginning the Iron Age. The secret of extracting and working iron was a key factor in the success of the Philistines.[4][5]
Historical developments in ferrous metallurgy can be found in a wide variety of past cultures and civilizations. This includes the ancient and medieval kingdoms and empires of the Middle East and Near East, ancient Iran, ancient Egypt, ancient Nubia, and Anatolia (Turkey), Ancient Nok, Carthage, the Greeks and Romans of ancient Europe, medieval Europe, ancient and medieval China, ancient and medieval India, ancient and medieval Japan, amongst others. Many applications, practices, and devices associated or involved in metallurgy were established in ancient China, such as the innovation of the blast furnace, cast iron, hydraulic-powered trip hammers, and double acting piston bellows.[6][7]
A 16th century book by Georg Agricola called De re metallica describes the highly developed and complex processes of mining metal ores, metal extraction and metallurgy of the time. Agricola has been described as the "father of metallurgy".[8]
Extraction
Extractive metallurgy is the practice of removing valuable metals from an ore and refining the extracted raw metals into a purer form. In order to convert a metal oxide or sulfide to a purer metal, the ore must be reduced physically, chemically, or electrolytically.
Extractive metallurgists are interested in three primary streams: feed, concentrate (valuable metal oxide/sulfide), and tailings (waste). After mining, large pieces of the ore feed are broken through crushing and/or grinding in order to obtain particles small enough where each particle is either mostly valuable or mostly waste. Concentrating the particles of value in a form supporting separation enables the desired metal to be removed from waste products.
Mining may not be necessary if the ore body and physical environment are conducive to leaching. Leaching dissolves minerals in an ore body and results in an enriched solution. The solution is collected and processed to extract valuable metals.
Ore bodies often contain more than one valuable metal. Tailings of a previous process may be used as a feed in another process to extract a secondary product from the original ore. Additionally, a concentrate may contain more than one valuable metal. That concentrate would then be processed to separate the valuable metals into individual constituents.
Alloys
Common engineering metals include aluminium, chromium, copper, iron, magnesium, nickel, titanium and zinc. These are most often used as alloys. Much effort has been placed on understanding the iron-carbon alloy system, which includes steels and cast irons. Plain carbon steels are used in low cost, high strength applications where weight and corrosion are not a problem. Cast irons, including ductile iron are also part of the iron-carbon system.
Stainless steel or galvanized steel are used where resistance to corrosion is important. Aluminium alloys and magnesium alloys are used for applications where strength and lightness are required.
Copper-nickel alloys (such as Monel) are used in highly corrosive environments and for non-magnetic applications. Nickel-based superalloys like Inconel are used in high temperature applications such as turbochargers, pressure vessel, and heat exchangers. For extremely high temperatures, single crystal alloys are used to minimize creep.
Production
In production engineering, metallurgy is concerned with the production of metallic components for use in consumer or engineering products. This involves the production of alloys, the shaping, the heat treatment and the surface treatment of the product. The task of the metallurgist is to achieve balance between material properties such as cost, weight, strength, toughness, hardness, corrosion, fatigue resistance, and performance in temperature extremes. To achieve this goal, the operating environment must be carefully considered. In a saltwater environment, ferrous metals and some aluminium alloys corrode quickly. Metals exposed to cold or cryogenic conditions may endure a ductile to brittle transition and lose their toughness, becoming more brittle and prone to cracking. Metals under continual cyclic loading can suffer from metal fatigue. Metals under constant stress at elevated temperatures can creep.
Metalworking processes
Main article: Metalworking
Metals are shaped by processes such as:
- casting - molten metal is poured into a shaped mold.
- forging - a red-hot billet is hammered into shape.
- flow forming
- rolling - a billet is passed through successively narrower rollers to create a sheet.
- Laser cladding - metallic powder is blown through a movable laser beam (e.g. mounted on a NC 5-axis machine). The resulting melted metal reach a substrate to form a melt pool. By moving the laser head, it is possible to stack the tracks and build up a 3D piece.
- extrusion - a hot and malleable metal is forced under pressure through a die, which shapes it before it cools.
- sintering - a powdered metal is heated in a non-oxidizing environment after being compressed into a die.
- metalworking
- machining - lathes, milling machines, and drills cut the cold metal to shape.
- fabrication - sheets of metal are cut with guillotines or gas cutters and bent and welded into structural shape.
Cold working processes, where the product’s shape is altered by rolling, fabrication or other processes while the product is cold, can increase the strength of the product by a process called work hardening. Work hardening creates microscopic defects in the metal, which resist further changes of shape.
Various forms of casting exist in industry and academia. These include sand casting, investment casting (also called the "lost wax process"), die casting and continuous casting.
Heat treatment
Main article: Heat treatment
Metals can be heat treated to alter the properties of strength, ductility, toughness, hardness or resistance to corrosion. Common heat treatment processes include annealing, precipitation strengthening, quenching, and tempering,[9]. The annealing process softens the metal by heating it and then allowing it to cool very slowly, which gets rid of stresses in the metal and makes the grain structure large and soft-edged so that when the metal is hit or stressed it dents or perhaps bends, rather than breaking; it is also easier to sand, grind, or cut annealed metal. Quenching is the process of cooling a high-carbon steel very quickly after you have heated it, thus "freezing" the steel's molecules in the very hard martensite form, which makes the metal harder. There is a balance between hardness and toughness in any steel, where the harder it is, the less tough or impact-resistant it is, and the more impact-resistant it is, the less hard it is. Tempering relieves stresses in the metal that were caused by the hardening process; tempering makes the metal less hard while making it better able to sustain impacts without breaking.
Often, mechanical and thermal treatments are combined in what is known as thermo-mechanical treatments for better properties and more efficient processing of materials. These processes are common to high alloy special steels, super alloys and titanium alloys.
Plating
Main article: Plating
Electroplating is a common surface-treatment technique. It involves bonding a thin layer of another metal such as gold, silver, chromium or zinc to the surface of the product. It is used to reduce corrosion as well as to improve the product's aesthetic appearance.
Thermal spraying
Main article: Thermal spraying
Thermal spraying techniques are another popular finishing option, and often have better high temperature properties than electroplated coatings.
Microstructure
Metallurgists study the microscopic and macroscopic properties using metallography, a technique invented by Henry Clifton Sorby. In metallography, an alloy of interest is ground flat and polished to a mirror finish. The sample can then be etched to reveal the microstructure and macrostructure of the metal. The sample is then examined in an optical or electron microscope, and the image contrast provides details on the composition, mechanical properties, and processing history.
Crystallography, often using diffraction of x-rays or electrons, is another valuable tool available to the modern metallurgist. Crystallography allows identification of unknown materials and reveals the crystal structure of the sample. Quantitative crystallography can be used to calculate the amount of phases present as well as the degree of strain to which a sample has been subjected.
See also
- Metallurgical failure analysis
- Archaeometallurgy
- CALPHAD
- Carbonyl metallurgy
- Cupellation
- Georg Agricola
- Goldbeating
- Gold phosphine complex
- Mineral industry
- National Institute of Foundry and Forge Technology
- Pyrometallurgy
- Timeline of materials technology
- Experimental Archaeometallurgy
References
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Wikiversity has learning materials about Topic:Metallurgical engineering |
- ^ a b Oxford English Dictionary, accessed 29 January 2011
- ^ doi:10.1016/j.jas.2010.06.012
- ^ Neolithic Vinca was a metallurgical culture Stonepages from news sources November 2007
- ^ a b W. Keller (1963) The Bible as History page 156 ISBN 0-340-00312-X
- ^ B. W. Anderson (1975) The Living World of the Old Testament page 154 ISBN 0-582-48598-3
- ^ R. F. Tylecote (1992) A History of Metallurgy ISBN 0-901462-88-8
- ^ Temple, Robert K.G. (2007). The Genius of China: 3,000 Years of Science, Discovery, and Invention (3rd edition). London: André Deutsch]. pp. 44-56. ISBN 978-0-233-00202-6.
- ^ Karl Alfred von Zittel (1901) History of Geology and Palaeontology page 15
- ^ Arthur Reardon (2011), Metallurgy for the Non-Metallurgist (2nd edition), ASM International, ISBN 978-1-61503-821-3
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Wikimedia Commons has media related to: Metallurgy |
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Translations:
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Metallurgy
Dansk (Danish)
n. - metallurgi
Nederlands (Dutch)
metallurgie (metaalkunde)
Français (French)
n. - métallurgie
Deutsch (German)
n. - Metallurgie
Ελληνική (Greek)
n. - μεταλλουργία
Italiano (Italian)
metallurgia
Português (Portuguese)
n. - metalurgia (f)
Español (Spanish)
n. - metalurgia
Svenska (Swedish)
n. - metallurgi
中文（简体）(Chinese (Simplified))
冶金, 冶金术
中文（繁體）(Chinese (Traditional))
n. - 冶金, 冶金術
العربيه (Arabic)
(الاسم) علم المعادن
עברית (Hebrew)
n. - תורת המתכות, מטלורגיה
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