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Naturally occurring tungsten consists of four stable isotopes (182 W, 183 W, 184 W, and 186 W) and one very long-lived radioisotope, 180 W. Theoretically, all five can decay into isotopes of element 72 by alpha emission, but only 180 W has been observed to do so, with a half-life of (1.8 ± 0.2) × 10 18 years; [36] [37] on average, this yields ...
Tungsten carbide (chemical formula: WC) is a chemical compound (specifically, a carbide) containing equal parts of tungsten and carbon atoms. In its most basic form, tungsten carbide is a fine gray powder, but it can be pressed and formed into shapes through sintering [7] for use in industrial machinery, engineering facilities, [8] molding blocks, [9] cutting tools, chisels, abrasives, armor ...
The saturation occurs because the tungsten layer stops diffusion of WF 6 molecules to the Si substrate which is the only catalyst of molecular decomposition in this process. [4] If the deposition occurs not in an inert atmosphere but in an oxygen-containing atmosphere (air), then instead of tungsten, a tungsten oxide layer is produced. [17]
Sodium tungstate is obtained by digestion of tungsten ores, the economically important representatives of which are tungstates, in base. Illustrative is the extraction of sodium tungstate from wolframite: [1] Fe/MnWO 4 + 2 NaOH + 2 H 2 O → Na 2 WO 4 ·2H 2 O + Fe/Mn(OH) 2. Scheelite is treated similarly using sodium carbonate.
[25] [26] In this applications similar dense materials like the more expensive osmium can also be used. The most common use for tungsten is as the compound tungsten carbide in drill bits, machining and cutting tools. The largest reserves of tungsten are in China, with deposits in Korea, Bolivia, Australia, and other countries.
In the absence of nucleators water can exist as a supercooled liquid down to −48.3 °C (−54.9 °F; 224.8 K) before freezing. [4] The metal with the highest melting point is tungsten, at 3,414 °C (6,177 °F; 3,687 K); [5] this property makes tungsten excellent for use as electrical filaments in incandescent lamps.
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Tungsten trioxide is a starting material for the synthesis of tungstates. Barium tungstate BaWO 4 is used as a x-ray screen phosphors. Alkali metal tungstates, such as lithium tungstate Li 2 WO 4 and cesium tungstate Cs 2 WO 4, give dense solutions that can be used to separate minerals. [1] Other applications, actual or potential, include ...