Bronze
Bronze is an alloy consisting of copper with about 12–12.5% tin and with the addition of other metals and sometimes non-metals or metalloids such as arsenic, phosphorus or silicon. These additions produce a range of alloys that may be harder than copper alone, or have other useful properties, such as stiffness, ductility, or machinability; the archeological period in which bronze was the hardest metal in widespread use is known as the Bronze Age. The beginning of the Bronze Age in India and western Eurasia is conventionally dated to the mid-4th millennium BC, to the early 2nd millennium BC in China; the Bronze Age was followed by the Iron Age starting from about 1300 BC and reaching most of Eurasia by about 500 BC, although bronze continued to be much more used than it is in modern times. Because historical pieces were made of brasses and bronzes with different compositions, modern museum and scholarly descriptions of older objects use the more inclusive term "copper alloy" instead. There are two basic theories as to the origin of the word.
Romance theoryThe Romance theory holds that the word bronze was borrowed from French bronze, itself borrowed from Italian bronzo "bell metal, brass" from either, bróntion, back-formation from Byzantine Greek brontēsíon from Brentḗsion ‘Brindisi’, reputed for its bronze. Proto-Slavic theoryThe Proto-Slavic theory reflects the philological issue that in the most of Slavonic languages word "bronza" corresponds to "war metal" while at the early stages of the Bronze working it was used exclusively for military purposes; the discovery of bronze enabled people to create metal objects which were harder and more durable than possible. Bronze tools, weapons and building materials such as decorative tiles were harder and more durable than their stone and copper predecessors. Bronze was made out of copper and arsenic, forming arsenic bronze, or from or artificially mixed ores of copper and arsenic, with the earliest artifacts so far known coming from the Iranian plateau in the 5th millennium BC, it was only that tin was used, becoming the major non-copper ingredient of bronze in the late 3rd millennium BC.
Tin bronze was superior to arsenic bronze in that the alloying process could be more controlled, the resulting alloy was stronger and easier to cast. Unlike arsenic, metallic tin and fumes from tin refining are not toxic; the earliest tin-alloy bronze dates to 4500 BC in a Vinča culture site in Pločnik. Other early examples date to the late 4th millennium BC in Egypt and some ancient sites in China and Mesopotamia. Ores of copper and the far rarer tin are not found together, so serious bronze work has always involved trade. Tin sources and trade in ancient times had a major influence on the development of cultures. In Europe, a major source of tin was the British deposits of ore in Cornwall, which were traded as far as Phoenicia in the eastern Mediterranean. In many parts of the world, large hoards of bronze artifacts are found, suggesting that bronze represented a store of value and an indicator of social status. In Europe, large hoards of bronze tools socketed axes, are found, which show no signs of wear.
With Chinese ritual bronzes, which are documented in the inscriptions they carry and from other sources, the case is clear. These were made in enormous quantities for elite burials, used by the living for ritual offerings. Though bronze is harder than wrought iron, with Vickers hardness of 60–258 vs. 30–80, the Bronze Age gave way to the Iron Age after a serious disruption of the tin trade: the population migrations of around 1200–1100 BC reduced the shipping of tin around the Mediterranean and from Britain, limiting supplies and raising prices. As the art of working in iron improved, iron improved in quality; as cultures advanced from hand-wrought iron to machine-forged iron, blacksmiths learned how to make steel. Steel holds a sharper edge longer. Bronze was still used during the Iron Age, has continued in use for many purposes to the modern day. There are many different bronze alloys, but modern bronze is 88% copper and 12% tin. Alpha bronze consists of the alpha solid solution of tin in copper.
Alpha bronze alloys of 4–5% tin are used to make coins, springs and blades. Historical "bronzes" are variable in composition, as most metalworkers used whatever scrap was on hand; the proportions of this mixture suggests. The Benin Bronzes are in fact brass, the Romanesque Baptismal font at St Bartholomew's Church, Liège is described as both bronze and brass. In the Bronze Age, two forms of bronze were used: "classic bronze", about 10% tin, was used in
Steel
Steel is an alloy of iron and carbon, sometimes other elements. Because of its high tensile strength and low cost, it is a major component used in buildings, tools, automobiles, machines and weapons. Iron is the base metal of steel. Iron is able to take on two crystalline forms, body centered cubic and face centered cubic, depending on its temperature. In the body-centered cubic arrangement, there is an iron atom in the center and eight atoms at the vertices of each cubic unit cell, it is the interaction of the allotropes of iron with the alloying elements carbon, that gives steel and cast iron their range of unique properties. In pure iron, the crystal structure has little resistance to the iron atoms slipping past one another, so pure iron is quite ductile, or soft and formed. In steel, small amounts of carbon, other elements, inclusions within the iron act as hardening agents that prevent the movement of dislocations that are common in the crystal lattices of iron atoms; the carbon in typical steel alloys may contribute up to 2.14% of its weight.
Varying the amount of carbon and many other alloying elements, as well as controlling their chemical and physical makeup in the final steel, slows the movement of those dislocations that make pure iron ductile, thus controls and enhances its qualities. These qualities include such things as the hardness, quenching behavior, need for annealing, tempering behavior, yield strength, tensile strength of the resulting steel; the increase in steel's strength compared to pure iron is possible only by reducing iron's ductility. Steel was produced in bloomery furnaces for thousands of years, but its large-scale, industrial use began only after more efficient production methods were devised in the 17th century, with the production of blister steel and crucible steel. With the invention of the Bessemer process in the mid-19th century, a new era of mass-produced steel began; this was followed by the Siemens–Martin process and the Gilchrist–Thomas process that refined the quality of steel. With their introductions, mild steel replaced wrought iron.
Further refinements in the process, such as basic oxygen steelmaking replaced earlier methods by further lowering the cost of production and increasing the quality of the final product. Today, steel is one of the most common manmade materials in the world, with more than 1.6 billion tons produced annually. Modern steel is identified by various grades defined by assorted standards organizations; the noun steel originates from the Proto-Germanic adjective stahliją or stakhlijan, related to stahlaz or stahliją. The carbon content of steel is between 0.002% and 2.14% by weight for plain iron–carbon alloys. These values vary depending on alloying elements such as manganese, nickel, so on. Steel is an iron-carbon alloy that does not undergo eutectic reaction. In contrast, cast iron does undergo eutectic reaction. Too little carbon content leaves iron quite soft and weak. Carbon contents higher than those of steel make a brittle alloy called pig iron. While iron alloyed with carbon is called carbon steel, alloy steel is steel to which other alloying elements have been intentionally added to modify the characteristics of steel.
Common alloying elements include: manganese, chromium, boron, vanadium, tungsten and niobium. Additional elements, most considered undesirable, are important in steel: phosphorus, sulfur and traces of oxygen and copper. Plain carbon-iron alloys with a higher than 2.1% carbon content are known as cast iron. With modern steelmaking techniques such as powder metal forming, it is possible to make high-carbon steels, but such are not common. Cast iron is not malleable when hot, but it can be formed by casting as it has a lower melting point than steel and good castability properties. Certain compositions of cast iron, while retaining the economies of melting and casting, can be heat treated after casting to make malleable iron or ductile iron objects. Steel is distinguishable from wrought iron, which may contain a small amount of carbon but large amounts of slag. Iron is found in the Earth's crust in the form of an ore an iron oxide, such as magnetite or hematite. Iron is extracted from iron ore by removing the oxygen through its combination with a preferred chemical partner such as carbon, lost to the atmosphere as carbon dioxide.
This process, known as smelting, was first applied to metals with lower melting points, such as tin, which melts at about 250 °C, copper, which melts at about 1,100 °C, the combination, which has a melting point lower than 1,083 °C. In comparison, cast iron melts at about 1,375 °C. Small quantities of iron were smelted in ancient times, in the solid state, by heating the ore in a charcoal fire and welding the clumps together with a hammer and in the process squeezing out the impurities. With care, the carbon content could be controlled by moving it around in the fire. Unlike copper and tin, liquid or solid iron dissolves carbon quite readily. All of these temperatures could be reached with ancient methods used since the Bronze Age. Since the oxidation rate of iron increases beyond 800 °C, it is important that smelting take place in a low-oxygen environment. Smelting, using carbon to reduce iro
Bi-metallic coin
Bi-metallic coins are coins consisting of two metals or alloys arranged with an outer ring around a contrasting center. Common circulating examples include the ₹10, €1, €2, 2 and 5 PLN, 50 CZK, 100 and 200 HUF, 1 and 2 BGN, British £1 and £2, Canadian $2, South African R5, Turkish 1 lira, IDR 1K, Hong Kong $10, Argentine $1, Brazilian R$1, Chilean $100 and $500, Colombian $500 and $1000, all Mexican coins of $1 or higher denomination. Bi-metallic coins have been issued for a long time, with known examples dating from the 17th century, while the Roman Empire issued special-occasion, large medallions with a center of bronze or copper and an outer ring of orichalcum, starting with the reign of Hadrian; the silver-center cent pattern produced by the United States in 1792 is another example. In the 1830s and 1840s, British medalist Joseph Moore produced large numbers of bi-metallic "penny model" and less common "halfpenny model" tokens, as a proposal to replace the large penny and halfpenny coins.
Though not legal tender, Moore's tokens were circulated and accepted at face value by many merchants. Despite their popularity, the Royal Mint rejected the proposal, did not reduce the size of the penny and halfpenny until decimalization. In recent times, the first circulating bi-metallic coin was the Italian 500 lire, first issued in 1982. Morocco, with its 5-dirhams coin in 1987. India introduced 10-rupee bi-metallic coins in 2009 that are dated 2006. Since 1996, Canada has produced bi-metallic $2 coins. Great Britain has issued a bi-metallic 2-pound coin since 1997; the first tri-metallic circulating coins were 20-francs coins introduced in France and Monaco in 1992. These were similar to the corresponding bi-metallic 10-francs coins, but had two rings instead of one; as well as circulating coins, where they are restricted to high-denomination coins, bi-metallic coins are used in commemorative issues made of precious metals. For example, the only bi-metallic coin of the United States is the $10 Library of Congress commemorative, made of a gold ring around a platinum center.
They are used as a way of securing against coin counterfeiting. The manufacturing process is similar to that of ordinary coins, except that two blanks are struck at the same time, deforming the separate blanks sufficiently to hold them together. Worldwide Bi-Metallic Collectors Club - website World bimetallic coin news - WBCN - website: new issues, country index and reference prices
Stainless steel
In metallurgy, stainless steel known as inox steel or inox from French inoxydable, is a steel alloy, with highest percentage contents of iron and nickel, with a minimum of 10.5% chromium content by mass and a maximum of 1.2% carbon by mass. Stainless steels are most notable for their corrosion resistance, which increases with increasing chromium content. Additions of molybdenum increase corrosion resistance in reducing acids and against pitting attack in chloride solutions. Thus, there are numerous grades of stainless steel with varying chromium and molybdenum contents to suit the environment the alloy must endure. Stainless steel's resistance to corrosion and staining, low maintenance, familiar luster make it an ideal material for many applications where both the strength of steel and corrosion resistance are required. Stainless steels are rolled into sheets, bars and tubing to be used in: cookware, surgical instruments, major appliances. Stainless steel's corrosion resistance, the ease with which it can be steam cleaned and sterilized, no need for surface coatings has influenced its use in commercial kitchens and food processing plants.
Stainless steels do not suffer uniform corrosion, like carbon steel, when exposed to wet environments. Unprotected carbon steel rusts when exposed to the combination of air and moisture; the resulting iron oxide surface layer is fragile. Since iron oxide occupies a larger volume than the original steel this layer expands and tends to flake and fall away exposing the underlying steel to further attack. In comparison, stainless steels contain sufficient chromium to undergo passivation, spontaneously forming a microscopically thin inert surface film of chromium oxide by reaction with the oxygen in air and the small amount of dissolved oxygen in water; this passive film prevents further corrosion by blocking oxygen diffusion to the steel surface and thus prevents corrosion from spreading into the bulk of the metal. This film is self-repairing if it is scratched or temporarily disturbed by an upset condition in the environment that exceeds the inherent corrosion resistance of that grade; the resistance of this film to corrosion depends upon the chemical composition of the stainless steel, chiefly the chromium content.
Corrosion of stainless steels can occur. It is customary to distinguish between 4 forms of corrosion: uniform, galvanic and SCC. Uniform corrosion takes place in aggressive environments chemical production or use and paper industries, etc; the whole surface of the steel is attacked and the corrosion is expressed as corrosion rate in mm/year Corrosion tables provide guidelines This is the case when stainless steels are exposed to acidic or basic solutions. Whether a stainless steel corrodes depends on the kind and concentration of acid or base, the solution temperature. Uniform corrosion is easy to avoid because of extensive published corrosion data or easy to perform laboratory corrosion testing. However, stainless steels are susceptible to localized corrosion under certain conditions, which need to be recognized and avoided; such localized corrosion is problematic for stainless steels because it is unexpected and difficult to predict. Acidic solutions can be categorized into two general categories, reducing acids such as hydrochloric acid and dilute sulfuric acid, oxidizing acids such as nitric acid and concentrated sulfuric acid.
Increasing chromium and molybdenum contents provide increasing resistance to reducing acids, while increasing chromium and silicon contents provide increasing resistance to oxidizing acids. Sulfuric acid is one of the largest tonnage industrial chemical manufactured. At room temperature Type 304 is only resistant to 3% acid while Type 316 is resistant to 3% acid up to 50 °C and 20% acid at room temperature, thus Type 304 is used in contact with sulfuric acid. Type 904L and Alloy 20 are resistant to sulfuric acid at higher concentrations above room temperature. Concentrated sulfuric acid possesses oxidizing characteristics like nitric acid and thus silicon bearing stainless steels find application. Hydrochloric acid will damage any kind of stainless steel, should be avoided. All types of stainless steel resist attack from phosphoric acid and nitric acid at room temperature. At high concentration and elevated temperature attack will occur and higher alloy stainless steels are required. In general, organic acids are less corrosive than mineral acids such as hydrochloric and sulfuric acid.
As the molecular weight of organic acids increase their corrosivity decreases. Formic acid is a strong acid. Type 304 can be used with formic acid. Acetic acid is the most commercially important of the organic acids and Type 316 is used for storing and handling acetic acid. Stainless steels Type 304 and 316 are unaffected by any of the weak bases such as ammonium hydroxide in high concentrations and at high temperatures; the same grades of stainless exposed to stronger bases such as sodium hydroxide at high concentrations and high temperatures will experience some etching and cracking. Increasing chromium and nickel contents provide increasing resistance. All grades resist damage from aldehydes and amines, though in the latter
Malagasy ariary
The ariary is the currency of Madagascar. It is subdivided into 5 iraimbilanja and is one of only two non-decimal currencies circulating; the names ariary and iraimbilanja derive from the pre-colonial currency, with ariary being the name for a silver dollar. Iraimbilanja means "one iron weight" and was the name of an old coin worth 1⁄5 of an ariary; the ariary was introduced in 1961. It was equal to 5 Malagasy francs. Coins and banknotes were issued denominated in both francs and ariary, with the sub-unit of the ariary, the iraimbilanja, worth 1⁄5 of an ariary and therefore equal to the franc; the ariary replaced the franc as the official currency of Madagascar on January 1, 2005. Coins and banknotes were denominated in both the official francs and the semi-official ariary and iraimbilanja since 1961. On early issues, the franc denomination was the most prominent. However, from 1978, higher value coins were issued denominated only in ariary. In 1993, new 500 ariary-2500 franc note and 5000 ariary-25,000 franc were issued with ariary more prominent.
On banknotes issued since July 31, 2003, the ariary denomination is displayed prominently and the franc denomination in small print. Lower denomination coins are now issued denominated in ariary but with the main design unchanged. In 1965, 1 franc and 2 francs coins were issued, followed by 5 francs in 1966 and 10 and 20 francs in 1970; the term "venty sy kirobo" derives from names used in the 19th century for 1⁄6 and 1⁄4 of a silver dollar or 5 francs piece, since 1⁄6+1⁄4=5⁄12 of 5 francs is 2 francs. In 1978, 10 and 20 ariary coins were issued; these were followed in 1992 by 50 ariary coins as well as smaller 10 and 20 ariary. In 2003–2004, 1 and 2 ariary coins not bearing the franc denomination were introduced. Coins in circulation are listed below. Bold denotes the most prominent denomination, while italic denotes an equivalence, not shown on the coin. In 1961, the Institut d’Émission Malgache introduced banknotes in denominations of 50, 100, 500, 1000 and 5000 francs; these notes were overprints on earlier notes of the Bank of Madagascar and Comoros, with the denomination in ariary included in the overprint.
Regular banknotes in the same denominations followed between 1963 and 1969. The denomination in ariary was written only in words, not numerals. On 12 June 1973, the Banky Foiben’ny Repoblika Malagasy was created by Ordinance No. 73-025, taking over the functions of the Institut d’Émission Malgache, including the issuance of banknotes. In 1974 new notes were issued in the same denominations. In December 1975, a draft constitution was overwhelmingly approved in a referendum, the Second Malagasy Republic, to be called the Repoblica Demokratika Malagasy, was proclaimed; as a result of the change in the country’s name, the former Banky Foiben’ny Repoblika Malagasy was renamed Banky Foiben’i Madagasikara. Resulting in a new series of notes which included 10,000 francs notes but did not include 50 or 100 francs. In 1993, notes for 500 ariary and 5000 ariary were introduced which bore the ariary denominations in numerals as well as the franc denominations in smaller numerals. However, in 1998, these notes were replaced by new issues which only gave the franc denominations in numerals.
In 2003–2004, new notes were introduced in denominations of 100, 200, 500, 1000, 2000, 5000 and 10,000 ariary. These notes bear the franc denominations on notes up to 1000 ariary in small numerals. In 2017, the Bank Foiben’i Madagasikara introduced a new family of banknotes; the new series of notes, like its previous series, remains "Madagascar and its Riches", highlighting its economic activities, biodiversity and tourist sites. Part of this series includes a new denomination, 20,000 ariary; the first four denominations in this series, 2,000-, 5,000-, 10,000 and 20,000 ariary were issued on July 17, 2017. The four other denominations, 100-, 200-, 500 and 1,000 ariary, were issued on September 17, 2017. Banknotes in circulation are listed below. Economy of Madagascar Historical and current banknotes of Madagascar
Economy of Mauritania
A majority of the population of Mauritania depends on agriculture and livestock for a livelihood though most of the nomads and many subsistence farmers were forced into the cities by recurrent droughts in the 1970s and 1980s. Mauritania has extensive deposits of iron ore, which account for 50% of total exports; the decline in world demand for this ore, has led to cutbacks in production. With the current rise in metal prices and copper mining companies are opening mines in the interior; the nation's coastal waters are among the richest fishing areas in the world, but overexploitation by foreigners threatens this key source of revenue. The country's first deep water port opened near Nouakchott in 1986. In recent years and economic mismanagement have resulted in a buildup of foreign debt. In March 1999, the government signed an agreement with a joint World Bank-International Monetary Fund mission on a $54 million enhanced structural adjustment facility; the economic objectives have been set for 1999–2002.
Privatization remains one of the key issues. This is a chart of trend of gross domestic product of Mauritania at market prices estimated by the International Monetary Fund with figures in millions of Mauritanian Ougulyas. Current GDP per capita of Mauritania grew 82% in the Sixties reaching a peak growth of 166% in the Seventies, but this proved unsustainable and growth scaled back to 14% in the Eighties. It shrank by 29% in the Nineties. Mean wages were $0.97 per man-hour in 2009. The following table shows the main economic indicators in 1980–2017. In 2007, mining industries accounted for well over 35 per cent of the Mauritanian economy, with the fish industry so much as 54%. Diversification of the economy into non-mining industries remains a long-term issue. Mauritania is a net importer of food importing 70% of its domestic food needs. In February 2006, the Mauritanian government denounced amendments to an oil contract made by former leader Maaouiya Ould Taya with Woodside Petroleum, an Australian company.
In 2004, Woodside had agreed to invest $US 600 million in developing Mauritania's Chinguetti offshore oil project. The controversial amendments, which Mauritanian authorities declared had been signed "outside the legal framework of normal practice, to the great detriment of our country", could cost Mauritania up to $200 million a year, according to BBC News. Signed by Woodside two weeks after the February 1, 2005 legislation authorizing the four amendments, they provided for a lower state quota in the profit-oil, reduced taxes by 15 percent in certain zones, they eased environmental constraints, extended the length and scope of the exploitation and exploration monopoly, among other measures. The disputed amendments were signed by former oil minister Zeidane Ould Hmeida in February 2004 and March 2005. Hmeida was arrested in January 2006 on charges of "serious crimes against the country's essential economic interests". Nouakchott's authorities declared that the government would seek international arbitration, which Woodside contemplated.
Discovered in 2002, Chinguetti has proven reserves of about 120,000,000 barrels of oil. At the end of December 2005, authorities estimated that in 2006, the oil profits would be 47 billion ouguiyas and represent a quarter of the state budget, according to RFI; some U. S. oil companies are alleged to be playing a part in Mauritania's oil related corruption. Economy of Africa Slavery in Mauritania List of companies based in Mauritania Mauritania portal Business and economics portal Africa portal This article incorporates public domain material from the CIA World Factbook website https://www.cia.gov/library/publications/the-world-factbook/index.html. Economy of Mauritania at Curlie Mauritania latest trade data on Ivana. "EU-Mauritania fisheries agreements". Library Briefing. Library of the European Parliament. Retrieved 17 June 2013
Kremnica Mint
The Kremnica Mint is a state-owned mint situated in Kremnica, Slovakia. The predecessor of current Mincovňa Kremnica, š. p. was established in 1328, for nearly seven centuries it has continuously been producing mint articles. Kremnica Mint was established in 1328 when Kremnica was promoted to a free royal town by the Hungarian King Charles Robert of Anjou. Kremnica ducats were well-known because of their good quality and were considered the hardest currency in Central Europe. Available historical records report that 21.5 million ducats were minted at the Kremnica Mint throughout its history. The aggregate value of this amount, measured at today's prices of gold, would be three billion US dollars; the mint became outdated by the beginning of the 20th century, many called for new equipment and for the mint to be moved to Budapest. However, this did not happen until the end of World War I; as the Czech troops invaded Northern Hungary, the Károlyi government ordered to move the equipment and noble metal stock to Budapest.
The Hungarian Government started to mint the first coins with the faulty machines and worn-out dies in Csepel. Coins minted in 1922 bore the KB mint mark; the Czechoslovak government had to set up a new mint as well, since not more than the buildings were left in Kremnica. Work on the new machinery started in 1921. Since the Kremnica Mint has manufactured all the coins used by the Czechoslovak and Slovak state and minted coins for 25 other countries. Since Kremnica was the site of the sole mint of the Czechoslovak state, the Czech protectorate was supplied with coins by Germany, the Czech Republic established its own mint. Kremnica Mint manufactures both circulation coins and commemorative coins for the National Bank of Slovakia, but the Mint's available capacities and quality standards make it capable of supplying coins to other countries worldwide. In March 2013 the Mint won a contract to produce 175 million Sri Lankan 10 Rupee pieces with total value of the contract of 6,032 million USD; this contract is valuable for Kremnica Mint as it succeeded in the field dominated by the Royal Mint.
Kremnica Mint established its own coin shop in 2006. The shop is placed inside the reconstructed historical building from 1450. An exposition of minting is part of the coin shop and it includes a remaining set of a historical striking machines - Vulkan. In addition to historical striking machines, visitors could observe coinage on modern striking machines; the first mint mark on coins minted in Kremnica was C, this was changed to K under Sigismund and K-B. With a decree from 16 June 1766, Maria Theresa uniformized the mint marks of the Austrian Empire, the new alphabetical system showed the importance of the mint: Körmöcbánya received letter B; this was changed back to K. B. temporarily in 1848-49 and in 1868. The K. B. mint mark was used after evacuation of the mint to Budapest until 1922. The Mincovňa Kremnica uses its initials as mint mark. List of oldest companies Homepage Mint Kremnica - short history & photos
Mauritania
Sahrawi Republic
