Tungsten disulfide

Sulfides. Tungsten disulfide [12138-09-9] WS2, although found in nature, is usually prepared by heating tungsten powder with sulfur at 900°C. 

Tungsten disulfide forms adherent, soft, continuous films on a variety of surfaces and exhibits good lubricating properties similar to molybdenum disulfide and graphite (51) (see also Lubrication and lubricants). Itis also reported to be a semiconductor (qv). 

Miyake, S., Sekine, Y., Noshiro, J., and Watanabe, S., Low-Friction and Long-Life Solid Lubricant Films Structured of Nanoperiod Tungsten Disulfide and Molybdenum Disulfide Multilayer, Jpn. J. Appl. Rhys., Vol. 43, 2004, pp. 4338-4343. 

Tschermigite, see Aluminum ammonium bis(sulfate) Tungstenite, see Tungsten disulfide Tungstite, see Hydrogen tungstate... 

Tungsten disulfide (WS ) is used as a solid lubricant that can withstand high temperatures. It is also used as a spray lubricant. 

Tests showed that liquid lubricants do not even provide adequate lubrication in the lower Vacuums of space simulators. Solid lubricants, such as molybdenum disulfide, tungsten disulfide. and the soft metals have given better results. However, the known data about space lubricants are results of simulator measurements made in the pressure range of 10 s to 1C6 torr which does not simulate real space conditions, and therefore, these available data cannot be considered completely valid. It can be expected that definite data on lubricant performance in a vacuum will be obtained by conducting tests in a simulator that reaches the low 10"10 torr range. At this press level, the monolayer formation time is increased to at least several hours which will result in a sufficient time span for observing the metal... 

The physical-chemical properties of a synthetic gallophosphate molecular sieve, the 30-A supercage cloverite , have been assessed [18]. Instead of attempting to list the burgeoning number of fullerene publications, attention is drawn to the formation and characterization of fullerene-like nanocrystals of tungsten disulfide [19,20]. Preparation, characterization and utilization of carbon nanotubes have been the subject of a number of reports from several laboratories [21-27]. 

Tungsten Disulfide and Molybdenum Disulfide. Arrhenius parameters reported for reactions on both these catalysts (222- 225) were close to two compensation lines, characteristic of cracking and exchange processes (Table II, O and P). Since the reactants studied in this work were different from those used in kinetic measurements on tungsten metal, no direct comparison of activities is appropriate. Data for reactions of thiophene did not correlate with either line. 

Tungsten disulfide (12) is a bluish-black substance with a density of 7.5 which crystallizes in the hexagonal system. It is stable in the absence... 

In normal vapor-phase operation the catalyst maintained its activity for 1 to 2 years, although some batches have been used for 5 years. The decrease in activity of the catalyst is caused by the irreversible absorption of high-molecular-weight hydrocarbons. Ash (e.g., iron phenolates) -containing feedstocks cause a more rapid loss of activity. Analyses of used catalysts indicated carbon contents of about 2%. Tungsten disulfide is isomorphous with molybdenum sulfide, and many of the catalytic properties of these two compounds are similar. X-ray analyses of the catalyst showed a hexagonal lattice (13). The primary size of the crystallites is about 3 X 10-7 cm. in height and twice that in width. Microscopic examinations showed that the crystals are pseudomorphous to the... 

Pig. 1. Adsorption of hydrogen on tungsten disulfide. I. Catalyst degassed at 300°C. II. Catalyst H2 treated and degassed at 300°C. 

Hydrogenation with Tungsten Disulfide as Catalyst Reaction without Change of the Carbon Skeleton... 

Tungsten disulfide, like molybdenum disulfide, exists both in the hexagonal and rhombohedral forms15). Thermal decomposition of WS3 is similar to that of MoS3. 

Prokudina, V.K., Kalikhman, V.L., Golubnichaya, A.A., Borovinskaya, I.P. and Merzhanov, A.G., Synthetic Molybdenum and Tungsten Disulfides, Soviet Powder Metallurgy and Metal Ceramics, 17, 450, (1978). 

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