Density of tungsten

Besides the material based characteristics, the difference of density of the used particle/substrate combination is a very important criterion. The difference of density influences the contrast of the radiographic tests. Tungsten carbides were used as mechanically resistant particles and titanium based alloys as substrate. The substrate material is marked by an advantageous relation of strength to density. This material is often used in aeronautics, astronautics, and for modification of boundary layers. The density of tungsten carbide (15.7 g/cm ) is about 3.5 times higher than the density of titanium (4.45-4.6 g/cm ). 

What would the density of tungsten he if its structure were ccp rather than bcc Its actual density is 19.3 g-cm J. 

Metals with bcc structures, like tungsten, are not close packed. Therefore, their densities would be greater if they were to change to a cubic close-packed structure (under pressure, for instance). What would the density of tungsten be if it had a cubic close-packed structure rather than bcc Its actual density is... 

The properties, crystal habit, and x-ray pattern of tungsten(IV) dichloride oxide are very similar to those of molybdenum(IV) dichloride oxide.8 Stoichiometric tungsten(IV) dichloride oxide, which forms gold-brown needles, is stable under atmospheric conditions and is not attacked by water, dilute or concentrated cold acids, ammonia, or organic solvents, such as acetone, ethanol, 2-methoxyethanol, chloroform, and diethyl ether. However, it decomposes in a solution of sodium hydroxide and forms a black precipitate, which disappears when hydrogen peroxide is added and yields a clear, yellow solution. The density of tungsten(IV) dichloride oxide, determined pycnometrically as previously mentioned, is 5.92 g./cc. 

Shen JJ, Costas WB, Cook LM. The effect of post chemical mechanical planarization buffing on defect density of tungsten and oxide wafers. J Electorchem Soc 1998 145(12) 4240-4243. 

The density of tungsten dioxide, according to Karsten, is 12T109. It is stable in the air but is readily oxidised. Heated in oxygen, it yields the trioxide at 500° C. in nitrous oxide or nitric oxide, the blue oxide, W2O3, re.sults, while nitrogen peroxide yields the trioxide. ... 

Boron fibers have at their core a tungsten (ca. 12 to 15 pm in diameter) or carbon fiber, which serves as a substrate during manufacture. Due to the high density of tungsten (19.3 Mg/m- ), a fiber thickness of 100 to 200 pm is necessary to achieve a low overall density for the fiber (ca. 2.6 Mg/m ). Therefore, latterly deposition on carbon fibers (density 1.8 Mg/m, diameter 8 to 10 pm) has been favored. This development has been driven by their commercial availability of carbon fibers. In addition to their low density (ca. 2.0 to 2.3 Mg/m- ) these fibers exhibit a low surface roughness and low internal stress. 

The transition metal tungsten (W) assumes Z)cc-stmcture. The atomie radius of tungsten atoms is 1.37 A (r = 1.37xl0 em) and the molar mass of tungsten is Mw = 183.84 g/mole. What is the density of tungsten metal ... 

We know that when we are dealing with Z)cc-structures eaeh unit eell eontains 2 atoms (see Table 2- 3 on page 84). The density of tungsten metal can thus he determined as follows ... 

The greater electron density of tungsten centres and the more electron-rich Tp ligand mean that protonation of the dicarbonyl complex Tp W( = CH)(CO)2 produces the cationic oc-agostic methylidene salts [Tp W( = CH2)(CO)2][BX4] (X = F, C6H3(CF3)2-3,5). ... 

The new metal s density was determined to 17.6. Pure tungsten metal has a density of 19.3 g/cm. This shows that the metal obtained was not pure but was partly tungsten carbide. This metal is also a very strong carbide former. The density of tungsten carbide WC is 15.8 g/cm. A simple stoichiometric calculation shows that a mixture of 48.6% WC and 51.4% W has a density of exactly 17.6. 

Tungsten has a body-centered cubic crystal structure. Using a metallic radius of 139 pm for the W atom, calculate the density of tungsten. 

In all spent researches the received ratio signal / noise and sensitivity for revealed defects, distribution of material density and the weights of high density components (tungsten, lead, uranium) are well agreed with results of alternate physics-chemical methods of analyses... 

The element is silvery white with a metallic luster its density is exceeded only by that of platinum, iridium, and osmium, and its melting point is exceeded only by that of tungsten and... 

Specifications. The use of tungsten hexafluoride in CVD appHcations in the manufacture of high density siUcon chips requires a high purity product, essentially free of all metallic contaminants. Several grades of WF are available. Table 2 shows the specifications for three grades of WF. ... 

Density is a particularly important characteristic of alloys used in rotating machinery, because centrifugal stresses increase with density. Densities of the various metals in Table 1 range from 6.1 to 19.3 g/cm. Those of iron, nickel, and cobalt-base superaHoys fall in the range 7-8.5 g/cm. Those alloys which contain the heavier elements, ie, molybdenum, tantalum, or tungsten, have correspondingly high densities. 

High density tungsten alloy machine chips are recovered by oxidation at about 850°C, foUowed by reduction in hydrogen at 700—900°C. Typically, the resultant powders are about 3-p.m grain size and resinter readily. There can be some pickup of refractory materials used in furnace constmction, which must be controUed. This process is important commercially. Eor materials that may be contaminated with other metals or impurities, the preferred recovery process is the wet chemical conversion process used for recovery of tungsten from ores and process wastes. Materials can always be considered for use as additions in alloy steel melting. 

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