Like evaporation tungsten boat, tungsten crucible is also a typical product of refractory metal tungsten. It is a product with metal tungsten powder as the main raw material. It is a high-temperature resistant vessel with a tungsten content generally higher than 99.95%. It is generally cylindrical in shape with a diameter between 10mm and 500mm and a height between 10mm and 750mm.
From the perspective of physical and chemical properties, the characteristics of tungsten crucible include high specific gravity, high melting point, high boiling point, low vapor pressure, low evaporation rate, low thermal expansion coefficient, corrosion resistance, wear resistance, good thermal conductivity, etc. Note: According to different manufacturing processes, tungsten crucibles can be divided into forging, sintering, welding, stamping, spinning, etc., among which the densities of forging and sintering are greater than 19.35g/cm3 and 18.5g/cm3 respectively; adding a certain amount of rare earth elements during the manufacture of pure tungsten crucibles can improve the oxidation resistance of the crucible, thereby extending the service life of the product.
From the production method point of view, the preparation steps of tungsten crucible include batching and mixing, isostatic pressing, shaping, sintering and finishing. The batching uses four different tungsten powders with a particle size range of 1.0~5.0um; the isostatic pressing pressure is about 200MPa, the holding time is about 7 minutes; the sintering temperature is about 2300°C, and the sintering time is about 7 hours.
From the use point of view, tungsten crucibles are widely used in rare earth smelting, quartz glass, electronic spraying, crystal growth and other industries. They are mainly used as rare earth metal smelting furnaces, quartz glass melting furnaces, induction furnace heating elements, single crystal furnace high temperature containers, sapphire single crystal growth furnaces, high temperature vacuum furnaces and other industrial furnaces. The working temperature is generally above 2000°C. Note: During the growth of sapphire crystals, the tungsten crucible should have the characteristics of no internal cracks, precise size, smooth inner and outer walls, etc.