-
81 Charpy, Augustin Georges Albert
SUBJECT AREA: Metallurgy[br]b. 1 September 1865 Ouillins, Rhône, Franced. 25 November 1945 Paris, France[br]French metallurgist, originator of the Charpy pendulum impact method of testing metals.[br]After graduating in chemistry from the Ecole Polytechnique in 1887, Charpy continued to work there on the physical chemistry of solutions for his doctorate. He joined the Laboratoire d'Artillerie de la Marine in 1892 and began to study the structure and mechanical properties of various steels in relation to their previous heat treatment. His first memoir, on the mechanical properties of steels quenched from various temperatures, was published in 1892 on the advice of Henri Le Chatelier. He joined the Compagnie de Chatillon Commentry Fourchamboult et Decazeville at their steelworks in Imphy in 1898, shortly after the discovery of Invar by G.E. Guillaume. Most of the alloys required for this investigation had been prepared at Imphy, and their laboratories were therefore well equipped with sensitive and refined dilatometric facilities. Charpy and his colleague L.Grenet utilized this technique in many of their earlier investigations, which were largely concerned with the transformation points of steel. He began to study the magnetic characteristics of silicon steels in 1902, shortly after their use as transformer laminations had first been proposed by Hadfield and his colleagues in 1900. Charpy was the first to show that the magnetic hysteresis of these alloys decreased rapidly as their grain size increased.The first details of Charpy's pendulum impact testing machine were published in 1901, about two years before Izod read his paper to the British Association. As with Izod's machine, the energy of fracture was measured by the retardation of the pendulum. Charpy's test pieces, however, unlike those of Izod, were in the form of centrally notched beams, freely supported at each end against rigid anvils. This arrangement, it was believed, transmitted less energy to the frame of the machine and allowed the energy of fracture to be more accurately measured. In practice, however, the blow of the pendulum in the Charpy test caused visible distortion in the specimen as a whole. Both tests were still widely used in the 1990s.In 1920 Charpy left Imphy to become Director-General of the Compagnie des Aciéries de la Marine et Homecourt. After his election to the Académie des Sciences in 1918, he came to be associated with Floris Osmond and Henri Le Chatelier as one of the founders of the "French School of Physical Metallurgy". Around the turn of the century he had contributed much to the development of the metallurgical microscope and had helped to introduce the Chatelier thermocouple into the laboratory and to industry. He also popularized the use of platinum-wound resistance furnaces for laboratory purposes. After 1920 his industrial responsibilities increased greatly, although he continued to devote much of his time to teaching at the Ecole Supérieure des Mines in Paris, and at the Ecole Polytechnique. His first book, Leçons de Chimie (1892, Paris), was written at the beginning of his career, in association with H.Gautier. His last, Notions élémentaires de sidérurgie (1946, Paris), with P.Pingault as co-author, was published posthumously.[br]BibliographyCharpy published important metallurgical papers in Comptes rendus… Académie des Sciences, Paris.Further ReadingR.Barthélémy, 1947, "Notice sur la vie et l'oeuvre de Georges Charpy", Notices et discours, Académie des Sciences, Paris (June).M.Caullery, 1945, "Annonce du décès de M.G. Charpy" Comptes rendus Académie des Sciences, Paris 221:677.P.G.Bastien, 1963, "Microscopic metallurgy in France prior to 1920", Sorby Centennial Symposium on the History of Metallurgy, AIME Metallurgical Society Conference Vol.27, pp. 171–88.ASDBiographical history of technology > Charpy, Augustin Georges Albert
-
82 Chevenard, Pierre Antoine Jean Sylvestre
SUBJECT AREA: Metallurgy[br]b. 31 December 1888 Thizy, Rhône, Franced. 15 August 1960 Fontenoy-aux-Roses, France[br]French metallurgist, inventor of the alloys Elinvar and Platinite and of the method of strengthening nickel-chromium alloys by a precipitate ofNi3Al which provided the basis of all later super-alloy development.[br]Soon after graduating from the Ecole des Mines at St-Etienne in 1910, Chevenard joined the Société de Commentry Fourchambault et Decazeville at their steelworks at Imphy, where he remained for the whole of his career. Imphy had for some years specialized in the production of nickel steels. From this venture emerged the first austenitic nickel-chromium steel, containing 6 per cent chromium and 22–4 per cent nickel and produced commercially in 1895. Most of the alloys required by Guillaume in his search for the low-expansion alloy Invar were made at Imphy. At the Imphy Research Laboratory, established in 1911, Chevenard conducted research into the development of specialized nickel-based alloys. His first success followed from an observation that some of the ferro-nickels were free from the low-temperature brittleness exhibited by conventional steels. To satisfy the technical requirements of Georges Claude, the French cryogenic pioneer, Chevenard was then able in 1912 to develop an alloy containing 55–60 per cent nickel, 1–3 per cent manganese and 0.2–0.4 per cent carbon. This was ductile down to −190°C, at which temperature carbon steel was very brittle.By 1916 Elinvar, a nickel-iron-chromium alloy with an elastic modulus that did not vary appreciably with changes in ambient temperature, had been identified. This found extensive use in horology and instrument manufacture, and even for the production of high-quality tuning forks. Another very popular alloy was Platinite, which had the same coefficient of thermal expansion as platinum and soda glass. It was used in considerable quantities by incandescent-lamp manufacturers for lead-in wires. Other materials developed by Chevenard at this stage to satisfy the requirements of the electrical industry included resistance alloys, base-metal thermocouple combinations, magnetically soft high-permeability alloys, and nickel-aluminium permanent magnet steels of very high coercivity which greatly improved the power and reliability of car magnetos. Thermostatic bimetals of all varieties soon became an important branch of manufacture at Imphy.During the remainder of his career at Imphy, Chevenard brilliantly elaborated the work on nickel-chromium-tungsten alloys to make stronger pressure vessels for the Haber and other chemical processes. Another famous alloy that he developed, ATV, contained 35 per cent nickel and 11 per cent chromium and was free from the problem of stress-induced cracking in steam that had hitherto inhibited the development of high-power steam turbines. Between 1912 and 1917, Chevenard recognized the harmful effects of traces of carbon on this type of alloy, and in the immediate postwar years he found efficient methods of scavenging the residual carbon by controlled additions of reactive metals. This led to the development of a range of stabilized austenitic stainless steels which were free from the problems of intercrystalline corrosion and weld decay that then caused so much difficulty to the manufacturers of chemical plant.Chevenard soon concluded that only the nickel-chromium system could provide a satisfactory basis for the subsequent development of high-temperature alloys. The first published reference to the strengthening of such materials by additions of aluminium and/or titanium occurs in his UK patent of 1929. This strengthening approach was adopted in the later wartime development in Britain of the Nimonic series of alloys, all of which depended for their high-temperature strength upon the precipitated compound Ni3Al.In 1936 he was studying the effect of what is now known as "thermal fatigue", which contributes to the eventual failure of both gas and steam turbines. He then published details of equipment for assessing the susceptibility of nickel-chromium alloys to this type of breakdown by a process of repeated quenching. Around this time he began to make systematic use of the thermo-gravimetrie balance for high-temperature oxidation studies.[br]Principal Honours and DistinctionsPresident, Société de Physique. Commandeur de la Légion d'honneur.Bibliography1929, Analyse dilatométrique des matériaux, with a preface be C.E.Guillaume, Paris: Dunod (still regarded as the definitive work on this subject).The Dictionary of Scientific Biography lists around thirty of his more important publications between 1914 and 1943.Further Reading"Chevenard, a great French metallurgist", 1960, Acier Fins (Spec.) 36:92–100.L.Valluz, 1961, "Notice sur les travaux de Pierre Chevenard, 1888–1960", Paris: Institut de France, Académie des Sciences.ASDBiographical history of technology > Chevenard, Pierre Antoine Jean Sylvestre
-
83 Guillaume, Charles-Edouard
[br]b. 15 February 1861 Fleurier, Switzerlandd. 13 June 1938 Sèvres, France[br]Swiss physicist who developed two alloys, "invar" and "elinvar", used for the temperature compensation of clocks and watches.[br]Guillaume came from a family of clock-and watchmakers. He was educated at the Gymnasium in Neuchâtel and at Zurich Polytechnic, from which he received his doctorate in 1883 for a thesis on electrolytic capacitors. In the same year he joined the International Bureau of Weights and Measures at Sèvres in France, where he was to spend the rest of his working life. He retired as Director in 1936. At the bureau he was involved in distributing the national standards of the metre to countries subscribing to the General Conference on Weights and Measures that had been held in 1889. This made him aware of the crucial effect of thermal expansion on the lengths of the standards and he was prompted to look for alternative materials that would be less costly than the platinum alloys which had been used. While studying nickel steels he made the surprising discovery that the thermal expansion of certain alloy compositions was less than that of the constituent metals. This led to the development of a steel containing about 36 per cent nickel that had a very low thermal coefficient of expansion. This alloy was subsequently named "invar", an abbreviation of invariable. It was well known that changes in temperature affected the timekeeping of clocks by altering the length of the pendulum, and various attempts had been made to overcome this defect, most notably the mercury-compensated pendulum of Graham and the gridiron pendulum of Harrison. However, an invar pendulum offered a simpler and more effective method of temperature compensation and was used almost exclusively for pendulum clocks of the highest precision.Changes in temperature can also affect the timekeeping of watches and chronometers, but this is due mainly to changes in the elasticity or stiffness of the balance spring rather than to changes in the size of the balance itself. To compensate for this effect Guillaume developed another more complex nickel alloy, "elinvar" (elasticity invariable), whose elasticity remained almost constant with changes in temperature. This had two practical consequences: the construction of watches could be simplified (by using monometallic balances) and more accurate chronometers could be made.[br]Principal Honours and DistinctionsNobel Prize for Physics 1920. Corresponding member of the Académie des Sciences. Grand Officier de la Légion d'honneur 1937. Physical Society Duddell Medal 1928. British Horological Institute Gold Medal 1930.Bibliography1897, "Sur la dilation des aciers au nickel", Comptes rendus hebdomadaires des séances de l'Académie des sciences 124:176.1903, "Variations du module d"élasticité des aciers au nickel', Comptes rendushebdomadaires des séances de l'Académie des sciences 136:498."Les aciers au nickel et leurs applications à l'horlogerie", in J.Grossmann, Horlogerie théorique, Paris, Vol. II, pp. 361–414 (describes the application of invar and elinvar to horology).Sir Richard Glazebrook (ed.), 1923 "Invar and Elinvar", Dictionary of Applied Physics, 5 vols, London, Vol. V, pp. 320–7 (a succinct account in English).Further ReadingR.M.Hawthorne, 1989, Nobel Prize Winners, Physics, 1901–1937, ed. F.N.Magill, Pasadena, Salem Press, pp. 244–51.See also: Le Roy, PierreDVBiographical history of technology > Guillaume, Charles-Edouard
-
84 معدن
مَعْدِن \ metal: a mineral substance such as iron, silver, etc.. mineral: any natural substance that may be obtained from the earth (coal, gold, sand, oil, gas, etc.). \ كالمَعْدِن \ metallic: of metal; like metal: metallic colours; a metallic sound. \ مَعْدِن البلاتين \ platinum: a hard and valuable silvery metal, much used in jewellery. \ مَعْدِن التَّنْجستِن \ tungsten: a valuable grey-white metal used to strengthen steel. \ مَعْدِن خام \ ore: a kind of rock from which metal can be obtained: gold ore; iron ore. \ مَعْدِن الرّادْيُوم \ radium: a powerful radioactive metal that can be used for treating some diseases. \ مَعْدِن الرَّصاص \ lead: a soft heavy metal. \ مَعْدِن الكُرُوم \ chromium: a metal that makes a shining surface on other metals, used esp. on cars. \ مَعْدِن المَغْنِيزْيُوم \ magnesium: a silvery-white metal that burns with a bright light. \ مَعْدِن النِّيكَل \ nickel: a hard silvery metal, used for making coins, spoons, etc.. \ مَعْدِن اليُورانيوم \ uranium: a metal that provides atomic power.
Страницы
См. также в других словарях:
Platinum metals — Platinum Plat i*num, n. [NL., fr. Sp. platina, from plata silver, LL. plata a thin plate of metal. See {Plate}, and cf. {Platina}.] (Chem.) A metallic element of atomic number 78, one of the noble metals, classed with silver and gold as a… … The Collaborative International Dictionary of English
platinum metals — A generic term for a family of noble metals found with and resembling platinum. It includes ruthenium, rhodium, palladium, osmium, iridium, and platinum. They are used as catalysts in catalytic converters. Less than a tenth of a troy ounce is… … Dictionary of automotive terms
platinum metals — plural noun Chemistry the six metals platinum, palladium, ruthenium, osmium, rhodium, and iridium, which have similar properties and tend to occur together in nature … English new terms dictionary
platinum metals — … Useful english dictionary
Platinum prints — Platinum prints, also called platinotypes , are photographic prints made by a monochrome printing process that provides the greatest tonal range of any printing method using chemical development.Unlike the silver print process, platinum lies on… … Wikipedia
Platinum — Plat i*num, n. [NL., fr. Sp. platina, from plata silver, LL. plata a thin plate of metal. See {Plate}, and cf. {Platina}.] (Chem.) A metallic element of atomic number 78, one of the noble metals, classed with silver and gold as a precious metal,… … The Collaborative International Dictionary of English
Platinum black — Platinum Plat i*num, n. [NL., fr. Sp. platina, from plata silver, LL. plata a thin plate of metal. See {Plate}, and cf. {Platina}.] (Chem.) A metallic element of atomic number 78, one of the noble metals, classed with silver and gold as a… … The Collaborative International Dictionary of English
Platinum lamp — Platinum Plat i*num, n. [NL., fr. Sp. platina, from plata silver, LL. plata a thin plate of metal. See {Plate}, and cf. {Platina}.] (Chem.) A metallic element of atomic number 78, one of the noble metals, classed with silver and gold as a… … The Collaborative International Dictionary of English
Platinum sponge — Platinum Plat i*num, n. [NL., fr. Sp. platina, from plata silver, LL. plata a thin plate of metal. See {Plate}, and cf. {Platina}.] (Chem.) A metallic element of atomic number 78, one of the noble metals, classed with silver and gold as a… … The Collaborative International Dictionary of English
Platinum black — (Pt black) is a fine powder of platinum with good catalytic properties. The name of platinum black is due to its black color. Platinum black is widely used as a thin film covering solid platinum metal, forming platinum electrodes for applications … Wikipedia
Platinum — This article is about the chemical element. For other uses, see Platinum (disambiguation). iridium ← platinum → gold Pd ↑ Pt ↓ Ds … Wikipedia
