Wolframtrioxid Chemische Eigenschaften,Einsatz,Produktion Methoden
R-S?tze Betriebsanweisung:
R22:Gesundheitssch?dlich beim Verschlucken.
R36/37/38:Reizt die Augen, die Atmungsorgane und die Haut.
S-S?tze Betriebsanweisung:
S26:Bei Berührung mit den Augen sofort gründlich mit Wasser abspülen und Arzt konsultieren.
S36:DE: Bei der Arbeit geeignete Schutzkleidung tragen.
S37/39:Bei der Arbeit geeignete Schutzhandschuhe und Schutzbrille/Gesichtsschutz tragen.
Chemische Eigenschaften
Canary-yellow, heavy powder, darkorange
when heated and regains original color on
cooling. Insoluble in water, soluble
in caustic alkalies, soluble with difficulty in
acids. Noncombustible.
Physikalische Eigenschaften
Heavy yellow powder; turns dark orange on heating; reverts back to yellow on cooling; density 7.2 g/cm
3; melts at 1,472°C; insoluble in water; slightly soluble in acids; soluble in caustic alkalies.
Verwenden
manufacture of tungstates which are used for x-ray screens and for fireproofing fabrics.
synthetische
Tungsten trioxide is obtained as an intermediate in recovery of tungsten from its minerals (See Tungsten). In commerical processes tungstic acid, H2WO4, obtained from the mineral scheelite, may either be decomposed at high temperatures to form trioxide or dissolved in ammonium hydroxide solution and evaporated to yield ammonium paratungstate (APT) crystals, 5 (NH
4)
2O?12WO
3?11H
2O. The APT crystals are then washed, dried, and calcined at elevated temperatures to form tungsten trioxide
Tungsten trioxide, in general, can be made by heating metallic tungsten, its carbides, its lower oxides, or tungstic acid in air.
Allgemeine Beschreibung
Tungsten(VI) oxide (WO
3) is a semiconducting material with excellent electrochromic properties. It is a cost efficient material with a high optical modulation. It can be synthesized by a variety of methods which include chemical vapor deposition, electrodeposition, and other sol-gel based coating processes.
Hazard
Toxic material.
Sicherheitsprofil
Moderately toxic by
ingestion. Can react violently with ClF3, Li,
Cl2. See also TUNGSTEN COMPOUNDS.
Structure and conformation
The crystal structure of tungsten trioxide is temperature dependent. It is tetragonal at temperatures above 740℃, orthorhombic from 330 to 740 °C, monoclinic from 17 to 330 °C, triclinic from -50 to 17 °C, and monoclinic again at temperatures below -50 °C.The most common structure of WO3 is monoclinic with space group P21/n.
Wolframtrioxid Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
