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42-576: Ceramic materials and radiocarbon dating of the graves allow archaeologists to form a chrono-cultural sequence, further dividing the region's Iron Age into distinct phases. The Kisalian Graves date from the Early Kisalian phase (700 - 900 CE) to the Classic Kisalian phase (900 - 1200 CE). Nearly 200 Kisalian graves have been found in the following five cemeteries: Sanga, Katongo, Kamilamba, Kikulu, and Malemba-Nkulu. The grave goods found in

84-513: A burial site located in the western industrial zone of Varna , approximately 4 km from the city centre, internationally considered one of the key archaeological sites in world prehistory. The oldest gold treasure in the world, dating from 4,600 BC to 4,200 BC, was discovered at the site. The gold piece dating from 4,500 BC, found in 2019 in Durankulak , near Varna is another important example. Other signs of early metals are found from

126-410: 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 . Cold-working processes, in which the product's shape is altered by rolling, fabrication or other processes, while the product is cold, can increase the strength of

168-413: A liquid bath. Metallurgists study the microscopic and macroscopic structure of metals 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

210-401: A major concern. Cast irons, including ductile iron , are also part of the iron-carbon system. Iron-Manganese-Chromium alloys (Hadfield-type steels) are also used in non-magnetic applications such as directional drilling. Other engineering metals include aluminium , chromium , copper , magnesium , nickel , titanium , zinc , and silicon . These metals are most often used as alloys with

252-609: A result of increased trade and political organization, the population flourished. The increase in population density is evident in the areas surrounding the Upemba Depression to this day. Analysis of the remains found in the Kisalian Graves suggests that the population of the time was relatively young, with a significant proportion of individuals under 30. The graves also contain a roughly equal number of male and female individuals. Metallurgy Metallurgy

294-627: A smelted copper axe dating from 5,500 BC, belonging to the Vinča culture . The Balkans and adjacent Carpathian region were the location of major Chalcolithic cultures including Vinča , Varna , Karanovo , Gumelnița and Hamangia , which are often grouped together under the name of ' Old Europe '. With the Carpatho-Balkan region described as the 'earliest metallurgical province in Eurasia', its scale and technical quality of metal production in

336-579: A superior metal could be made, an alloy called bronze . This represented a major technological shift known as the Bronze Age . The extraction of iron from its ore into a workable metal is much more difficult than for copper or tin. The process 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

378-401: Is a chemical 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. This is done by selecting the coating material electrolyte solution, which is the material that is going to coat the workpiece (gold, silver, zinc). There needs to be two electrodes of different materials: one the same material as

420-426: Is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements , their inter-metallic compounds , and their mixtures, which are known as alloys . Metallurgy encompasses both the science and the technology of metals, including the production of metals and the engineering of metal components used in products for both consumers and manufacturers. Metallurgy

462-443: Is an industrial coating process that consists of a heat source (flame or other) and a coating material that can be in a powder or wire form, which is melted then sprayed on the surface of the material being treated at a high velocity. The spray treating process is known by many different names such as HVOF (High Velocity Oxygen Fuel), plasma spray, flame spray, arc spray and metalizing. Electroless deposition (ED) or electroless plating

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504-708: 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. Much effort has been placed on understanding iron –carbon alloy system, which includes steels and cast irons . Plain carbon steels (those that contain essentially only carbon as an alloying element) are used in low-cost, high-strength applications, where neither weight nor corrosion are

546-455: Is defined as the autocatalytic process through which metals and metal alloys are deposited onto nonconductive surfaces. These nonconductive surfaces include plastics, ceramics, and glass etc., which can then become decorative, anti-corrosive, and conductive depending on their final functions. Electroless deposition is a chemical processes that create metal coatings on various materials by autocatalytic chemical reduction of metal cations in

588-414: Is distinct from the craft of metalworking . Metalworking relies on metallurgy in a similar manner to how medicine relies on medical science for technical advancement. A specialist practitioner of metallurgy is known as a metallurgist. The science of metallurgy is further subdivided into two broad categories: chemical metallurgy and physical metallurgy . Chemical metallurgy is chiefly concerned with

630-654: Is found in the Balkans and Carpathian Mountains , as evidenced by findings of objects made by metal casting and smelting dated to around 6000-5000 BC. Certain metals, such as tin, lead, and copper can be recovered from their ores by simply heating the rocks in a fire or blast furnace in a process known as smelting. The first evidence of copper smelting, dating from the 6th millennium BC, has been found at archaeological sites in Majdanpek , Jarmovac and Pločnik , in present-day Serbia . The site of Pločnik has produced

672-545: Is the more common one in the United Kingdom . The / ˈ m ɛ t əl ɜːr dʒ i / pronunciation is the more common one in the United States US and is the first-listed variant in various American dictionaries, including Merriam-Webster Collegiate and American Heritage . The earliest metal employed by humans appears to be gold , which can be found " native ". Small amounts of natural gold, dating to

714-408: Is the science of obtaining metals from their concentrates, semi products, recycled bodies and solutions, and of considering reactions of metals with an approach of disciplines belonging to chemistry . As such, it involves reactivity of metals and it is especially concerned with the reduction and oxidation , and the chemical performance of metals. Subjects of study in chemical metallurgy include

756-527: The 6th–5th millennia BC totally overshadowed that of any other contemporary production centre. The earliest documented use of lead (possibly native or smelted) in the Near East dates from the 6th millennium BC, is from the late Neolithic settlements of Yarim Tepe and Arpachiyah in Iraq . The artifacts suggest that lead smelting may have predated copper smelting. Metallurgy of lead has also been found in

798-664: The Balkans during the same period. Copper smelting is documented at sites in Anatolia and at the site of Tal-i Iblis in southeastern Iran from c. 5000 BC. Copper smelting is first documented in the Delta region of northern Egypt in c. 4000 BC, associated with the Maadi culture . This represents the earliest evidence for smelting in Africa. The Varna Necropolis , Bulgaria , is

840-535: The Classic Kisalian phase, the material culture flourished with evidence of skilled artisans. The Kisalian period was also marked by significant religious and artistic expression, as evidenced by the elaborate funerary practices and the development of sophisticated artistic traditions, such as the production of pottery, sculpture, and other decorative objects. Grave goods from this phase include pottery, ivory, copper, cowrie, and carved bone dolls. The frequency of goods varied between sites, with women and children being among

882-543: The Indian Ocean, cowrie shells held great value to the Kisalian. The Kisalian used cowrie shells as a form of currency and decoration. Population increase led to more complex societies with elaborate social and political structures. The first instance of political complexity occurred during the Early Kisalian phase, indicated by an anvil and ceremonial axe found in one of the burial sites. The contents and location of

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924-467: The Kisalian period and likely displayed the wealth or status of an individual. Many Kisalian graves contained copper goods, in the form of personal adornments, despite the rarity of copper ore in the Upemba region. The presence of copper strongly suggests the presence of long-distance trade systems. It is believed that the number of copper goods in a grave corresponded with the status of the individual. During

966-403: The amount of phases present as well as the degree of strain to which a sample has been subjected. Current advanced characterization techniques, which are used frequently in this field are: Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Electron Backscattered Diffraction (EBSD) and Atom-Probe Tomography (APT). Chemical metallurgy Chemical metallurgy

1008-527: The burial sites strongly suggest long-distance trade, metallurgy , social hierarchy , and symbolism within the Kisalian phases. Many of the practices of the Luba people , who currently reside in the Upemba Depression, can be traced back to the Kisalian phases. Archaeologists' understanding of the Kisalian phases stems predominately from the grave goods at these sites. Common grave goods included ceramic, iron, copper, bone, and ivory. Long curved blades characterized

1050-416: The coating material and one that is receiving the coating material. Two electrodes are electrically charged and the coating material is stuck to the work piece. It is used to reduce corrosion as well as to improve the product's aesthetic appearance. It is also used to make inexpensive metals look like the more expensive ones (gold, silver). Shot peening is a cold working process used to finish metal parts. In

1092-480: The graves indicate that they were reserved for individuals of high social status, providing insight into the complex social hierarchy of these cultures. Linguistic and archaeological data allude to the Kisalian Graves as potentially the first archaeological evidence of slavery in Central Africa. The Kisalian phase saw a rapid increase in population growth, as shown by the significant number of burial sites. As

1134-619: 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". 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 sulphide to a purer metal, the ore must be reduced physically, chemically , or electrolytically . Extractive metallurgists are interested in three primary streams: feed, concentrate (metal oxide/sulphide) and tailings (waste). After mining, large pieces of

1176-402: 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

1218-508: The joining of metals (including welding , brazing , and soldering ). Emerging areas for metallurgists include nanotechnology , superconductors , composites , biomedical materials , electronic materials (semiconductors) and surface engineering . Metallurgy derives from the Ancient Greek μεταλλουργός , metallourgós , "worker in metal", from μέταλλον , métallon , "mine, metal" + ἔργον , érgon , "work" The word

1260-560: The late Paleolithic period, 40,000 BC, have been found in Spanish caves. Silver , copper , tin and meteoric iron can also be found in native form, allowing a limited amount of metalworking in early cultures. Early cold metallurgy, using native copper not melted from mineral has been documented at sites in Anatolia and at the site of Tell Maghzaliyah in Iraq , dating from the 7th/6th millennia BC. The earliest archaeological support of smelting (hot metallurgy) in Eurasia

1302-553: The noted exception of silicon, which is not a metal. Other forms include: In production engineering , metallurgy is concerned with the production of metallic components for use in consumer or engineering products. This involves production of alloys, shaping, heat treatment and surface treatment of 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,

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1344-512: The operating environment must be carefully considered. Determining the hardness of the metal using the Rockwell, Vickers, and Brinell hardness scales is a commonly used practice that helps better understand the metal's elasticity and plasticity for different applications and production processes. In a saltwater environment, most ferrous metals and some non-ferrous alloys corrode quickly. Metals exposed to cold or cryogenic conditions may undergo

1386-482: The ore feed are broken through crushing 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

1428-402: The piece being treated. The compression stress in the surface of the material strengthens the part and makes it more resistant to fatigue failure, stress failures, corrosion failure, and cracking. Thermal spraying techniques are another popular finishing option, and often have better high temperature properties than electroplated coatings. Thermal spraying, also known as a spray welding process,

1470-445: The process of shot peening, small round shot is blasted against the surface of the part to be finished. This process is used to prolong the product life of the part, prevent stress corrosion failures, and also prevent fatigue. The shot leaves small dimples on the surface like a peen hammer does, which cause compression stress under the dimple. As the shot media strikes the material over and over, it forms many overlapping dimples throughout

1512-666: The product by a process called work hardening . Work hardening creates microscopic defects in the metal, which resist further changes of shape. Metals can be heat-treated to alter the properties of strength, ductility, toughness, hardness and resistance to corrosion. Common heat treatment processes include annealing, precipitation strengthening , quenching, and tempering: Often, mechanical and thermal treatments are combined in what are known as thermo-mechanical treatments for better properties and more efficient processing of materials. These processes are common to high-alloy special steels, superalloys and titanium alloys. Electroplating

1554-1008: The production of metals. Metal production begins with the processing of ores to extract the metal, and includes the mixture of metals to make alloys . Metal alloys are often a blend of at least two different metallic elements. However, non-metallic elements are often added to alloys in order to achieve properties suitable for an application. The study of metal production is subdivided into ferrous metallurgy (also known as black metallurgy ) and non-ferrous metallurgy , also known as colored metallurgy. Ferrous metallurgy involves processes and alloys based on iron , while non-ferrous metallurgy involves processes and alloys based on other metals. The production of ferrous metals accounts for 95% of world metal production. Modern metallurgists work in both emerging and traditional areas as part of an interdisciplinary team alongside material scientists and other engineers. Some traditional areas include mineral processing, metal production, heat treatment, failure analysis , and

1596-641: The reduction and oxidation of metals, and the chemical performance of metals. Subjects of study in chemical metallurgy include mineral processing , the extraction of metals , thermodynamics , electrochemistry , and chemical degradation ( corrosion ). In contrast, physical metallurgy focuses on the mechanical properties of metals, the physical properties of metals, and the physical performance of metals. Topics studied in physical metallurgy include crystallography , material characterization , mechanical metallurgy, phase transformations , and failure mechanisms . Historically, metallurgy has predominately focused on

1638-787: The success of the Philistines . 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 in present-day Turkey , Ancient Nok , Carthage , the Celts , Greeks and Romans of ancient Europe , medieval Europe, ancient and medieval China , ancient and medieval India , ancient and medieval Japan , amongst others. A 16th century book by Georg Agricola , De re metallica , describes

1680-568: The third millennium BC in Palmela , Portugal, Los Millares , Spain, and Stonehenge , United Kingdom. The precise beginnings, however, have not be clearly ascertained and new discoveries are both continuous and ongoing. In approximately 1900 BC, ancient iron smelting sites existed in Tamil Nadu . In the Near East , about 3,500 BC, it was discovered that by combining copper and tin,

1722-586: The wealthiest. The Kisalian Graves contain evidence of trade with the Copperbelt and the East African coast. Despite the high demand for copper, the frequency of such luxury did not increase until the Classic Kisalian phase. The Classic Kisalian phase saw an increase in trade with the Copperbelt, thus ending the geographical isolation of the Upemba Depression. Imported from the East African coast and

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1764-434: Was originally an alchemist 's term for the extraction of metals from minerals, the ending -urgy signifying a process, especially manufacturing: it was discussed in this sense in the 1797 Encyclopædia Britannica . In the late 19th century, metallurgy's definition was extended to the more general scientific study of metals, alloys, and related processes. In English , the / m ɛ ˈ t æ l ər dʒ i / pronunciation

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