Tungsten history

Articles concerned with tungsten history usually start by describing the discovery of tungsten ores, compounds, and the element. In reality, however, the history of tungsten began with the formation of the tungsten atoms, a very long time ago. 

The work on the electrochemical generation of a solution of ceric sulphate from slurry of cerous sulphate in 1-2 M sulphuric acid was abandoned by BCR due to difficulties encountered in handling slurried reactants. A 6kW pilot reactor operated at 50 °C using a Ti plate anode and a tungsten wire cathode (electrolyte velocity about 2ms 1) produced 0.5 M Ce(S04)2 on the anode with a current efficiency of 60%. The usefulness of Ce(IV) has been limited by the counter anions [131,132], Problems include instability to oxidation, reactivity with organic substrates and low solubility. Grace found that use of cerium salts of methane sulfonate avoids the above problems. Walsh has summarized the process history, Scheme 6 [133],... 

The publications and correspondence of Bergman and Scheele contain interesting allusions to the de Elhuyar brothers, to Hjelm, and to the early history of the metals tungsten and molybdenum which they discovered. The presence of a new metal in pitchblende was recognized by Klaproth in 1789, but it remained for Peligot half a century later to isolate uranium. Chromium, now the most familiar element of the group, was the last to be discovered when the immortal French chemist Vauquelin finally isolated it in 1798 from a Siberian mineral. For further information about tungsten see pp. 284-301. 

Torbem Olof Bergman, 1735-1784. Swedish chemist, pharmacist, and physicist. He was among the first to investigate the compounds of manganese, cobalt, nickel, tungsten, and molybdenum. He was an immediate forerunner of Haiiy in the history of theoretical crystallography (68). 

Professor von Hevesy and Thai Jantzen separated hafnia from zirconia by repeated recrystallization of the double ammonium or potassium fluorides (20, 26). Metallic hafnium has been isolated and found to have the same crystalline structure as zirconium. A small specimen of the first metallic hafnium ever made is on permanent display at the American Museum of Natural History in New York City. Dr. von Hevesy, who prepared it, presented it to the Museum for the collection of chemical elements (29). A. E. van Arkel and J. H. de Boer prepared hafnium by passing the vapor of the tetraiodide over a heated tungsten filament (26, 30). 

Krebs, R.E. The History arul Use of Our Earth s Chemical Elements. A Reference Guide, Greenwood Publishing Group, Inc.. Westport, CT, 1998 Lassner, E. and W. Schubert Tungsten Properties, Chemistr i, Technology of the Element AUoys, and Chemical Compounds, Kluwer Academic Publishers, NorweU, MA, 1998. 

Electrophoretic deposition (EPD) is a colloidal process in which the charged colloidal particles are driven by a dc electric field to deposit on a substrate, forming a condensed film. This process is a combination of electrophoresis and deposition (Sarkar and Nicholson 1996). It has a long history and the first application was in 1927 for Th02 and tungsten deposition on a platinum cathode. Recently, photocatalyst semiconductor nanoparticles/microparticles have also been assembled by this... 

History.—Until the middle of the eighteenth century both scheelite and wolframite were considered to be ores of tin their real identity was first pointed out in 1781 by Scheele, who show ed that the mineral now bearing his name contained lime combined with a new acid, which he named tungstic acid. The metallic nature of the element was first demonstrated by Bergman. Further researches were undertaken by D Elhuyart, Juan, Jose, and others. The preparation of metallic tungsten, its industrial application (especially with regard to electrical glow lamps), and the study of its compounds have since been the subject of numerous researches. 

Occurrence—History—Preparation —Tungsten Pilanieiits—Physical Properties —Spectrum—Chemical Properties—Atomic Weight—Uses—Alloys. 

Two kinds of metal are found in chondrites grains composed of refractory elements (iridium, osmium, ruthenium, molybdenum, tungsten, and rhenium), which condense along with the refractory oxides above —1,600 K at 10 atm, and grains composed predominantly of iron, cobalt, and nickel, which condense with forster-ite and enstatite at —1,350-1,450 K. The former are associated with CAIs (Palme and Wlotzka 1976) and the latter with chondrules, typically type I or FeO-poor chondrules (B J 1998, pp. 244-278). Unfortunately, few chondrites preserve a good record of the formation history... 

Generally speaking, the indication of absolute values for the mechanical properties of polyciystalline tungsten is not appropriate as long as the related structure, structural history, type of impurity elements, their concentration, and kind of distribution cannot be precisely defined. However, for technical samples, this is especially impossible due to the high cost and the time required for analyses of such type. Therefore, any values given for... 

TABLE 1.9. Microhardness (kg-mm of Tungsten of Different Manufacturing History [1.39]... 

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