Tungsten crucible is a high-temperature resistant vessel made from high-purity tungsten powder (tungsten content >99.95%) through precise powder metallurgy and forming techniques. It maintains structural integrity and functional stability even in high-temperature environments, with its technological level influencing the precision of cutting-edge processes in fields like high-end crystal growth and special material smelting.
Image of tungsten crucible
The excellent properties of tungsten crucible stem from the intrinsic attributes of tungsten and optimized microstructure. Tungsten boasts a melting point of 3,410°C, a boiling point of 5,927°C, and a high density of 19.35 g/cm3, which are translated into unique performance characteristics through various forming processes:
Density and Compactness Differences: Forged crucible, processed via thermomechanical methods, align grains preferentially along the deformation direction, achieving a density of about 19.35 g/cm3, making it suitable for withstanding high-frequency thermal shocks. Sintered crucible (density around 18.5 g/cm3), though slightly less dense, benefits from uniformly distributed pores, offering advantages in controlling molten metal infiltration.
Rare Earth Modification: Adding rare earth oxides like Y?O? or La?O? to tungsten powder creates stable oxide particles through dispersion strengthening. These particles impede dislocation movement to enhance high-temperature strength and form a dense WO?-REO composite oxide film on the crucible surface, raising oxidation resistance and extending service life.
Image of tungsten crucible
The preparation of tungsten crucible involves: first, sieving tungsten powder to ensure uniform particle size, followed by isostatic pressing to form a rough blank; then machining the blank, performing medium-frequency sintering under hydrogen protection to improve density and strength; subsequent precision machining to control dimensional accuracy and surface roughness; and finally, comprehensive quality inspection with specialized packaging to ensure transport and storage quality.
In sapphire single-crystal growth, tungsten crucible, paired with the Czochralski method, enables stable crystal growth at high temperatures. Its low thermal expansion ensures better thermal matching with the crystal, reducing internal stress. In rare earth metal smelting, tungsten crucible is used in vacuum induction furnaces to melt rare earth oxides and perform reduction reactions, exhibiting strong resistance to molten rare earth metal corrosion. In nuclear fusion research, tungsten crucible serves as plasma-facing material test platforms, enduring high thermal loads and hydrogen ion bombardment with notable sputter resistance.
