Tungsten in Glass Industry
Quartz glass or quartz material is produced in special high-temperature furnaces due to the high melting temperatures (approx. 2000°C). The heart of such a furnace consists of a melting crucible, which is continually filled with quartz sand and heated to melting temperature.
Tungsten alloy is used widely as a constituent in the alloys of other metals, since it generally enhances high-temperature strength. Several types of tool steels and some stainless steels contain tungsten. Heat-resistant alloys, also termed super alloys, are nickel-, cobalt-, or iron-based systems containing varying amounts (typically 1.5–25 wt %) of tungsten. You can see tungsten alloy is a high-temperature resistance material.
Unalloyed tungsten (25% of tungsten consumption) in the form of wire is used as filaments in incandescent and fluorescent lamps, and as heating elements for furnaces and heaters. Because of its high electron emissivity, thorium-doped ( throated) tungsten wire is employed for direct cathode electronic filaments. Tungsten rods find use as lamp filament supports, electrical contacts, and electrodes for arc lamps.
Tungsten compounds (5% of tungsten consumption) have a number of industrial applications. Calcium and magnesium tungsten are used as phosphors in fluorescent lights and television tubes. Sodium tungsten is employed in the fireproofing of fabrics and in the preparation of tungsten-containing dyes and pigments used in paints and printing inks. Compounds such as WO3 and WS2 are catalysts for various chemical processes in the petroleum industry. Both WS2 and WSe2 are dry, high-temperature lubricants. Other applications of tungsten compounds have been made in the glass, ceramics, and tanning industries.
Platinum Tungsten for Glass Industry
Platinum and its alloys are used very widely in the glass industry because of their outstanding physical and chemical properties. These materials are excellently suited to the extremely complex service conditions as a result of their high mechanical strength at high temperatures under simultaneous corrosive conditions. Particularly advantageous properties of the platinum materials for this field of application are:
High melting points (above 1650°C)
Very good oxidation resistance
Good corrosion resistance against aggressive glass melts, gases and salts
Negligible contamination of the glass melts because of the extremely low solubility of platinum in the melt and the good corrosion stability
Minimal pick up of foreign substances from the glass melt
High mechanical strength at extremely high temperatures and good ductility
Good formability and weldability
Good electrical conductivity (advantageous for direct heating)
Amenability to complete recycling
Typical applications of platinum and platinum alloys in the glass industry are feeder systems (homogenization cells, stirrers, plunger cells, plungers, feeder tubes, outlet orifices), bubbler tubes, drain bushings, tank linings, melting crucibles, protective thermocouple thimbles, laboratory equipment, electrodes and glass fibre bushings. By using platinum alloys, the service lives of plant components can be greatly increased, and both the high quality of the glass melt and the achievement of precise dimensional and weight tolerances in glass products can be guaranteed much more readily than when refractory components are used.
The properties which are of greatest significance for the application of platinum and its alloys in the glass industry include the stress-rupture strength, the behavior during creep and rupture, the weldability and the resistance to corrosion.
