Tungsten Crucible

Like an evaporation tungsten boat, tungsten crucible is a typical product made from refractory metal tungsten, primarily using tungsten powder as the raw material. It is a high-temperature resistant vessel with the English name tungsten crucible. It generally contains over 99.95% tungsten and is typically cylindrical in shape, with diameters ranging from 10mm to 500mm, heights from 10mm to 750mm, and wall thicknesses from 8mm to 20mm.

Tungsten crucible is characterized by high density, high melting point, high boiling point, low vapor pressure, low evaporation rate, low thermal expansion coefficient, corrosion resistance, wear resistance, and excellent thermal conductivity. Depending on the manufacturing process, tungsten crucible can be produced through forging, sintering, welding, stamping, or spinning, with densities exceeding 19.35 g/cm³ for the forged type and 18.5 g/cm³ for the sintered type. Adding a small amount of rare earth elements during the production of pure tungsten crucibles can enhance their oxidation resistance, thereby extending their service life.

The preparation of a tungsten crucible involves the following steps: mixing raw materials, isostatic pressing, shaping, sintering, and finishing. Four types of tungsten powder with particle sizes ranging from 1.0 to 5.0 µm are used for mixing; isostatic pressing is performed at approximately 200 MPa with a holding time of about 7 minutes; sintering occurs at around 2,300°C for approximately 7 hours.

Tungsten crucible is widely used in industries such as rare earth smelting, quartz glass production, electronic spraying, and crystal growth. It primarily serves as a smelting furnace for rare earth metals, a quartz glass melting furnace, an induction furnace heating element, a high-temperature container for single-crystal furnaces, a sapphire single-crystal growth furnace, and a high-temperature vacuum furnace, operating at temperatures typically above 2,000°C. For sapphire crystal growth, tungsten crucible must feature no internal cracks, precise dimensions, and smooth inner and outer walls.

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