METHOD OF FABRICATING HEAVY MELTING POTS MADE OF TUNGSTEN Russian patent published in 2009 - IPC C23C16/14 C23C16/455 

FIELD: metallurgy.

SUBSTANCE: invention relates to receiving of molded products; particularly, heavy melting pots made of tungsten. In reaction chamber it is implemented recovery of tungsten by hydrogen from tungsten hexafluoride. Tungsten is precipitated on outside surface of copper substrate, heated till the temperature 500-650°C at atmospheric pressure in reaction chamber. At the first stage it is implemented feeding of gas mixture of tungsten hexafluoride and hydrogen into reaction chamber bottom-up perpendicularly to the surface of formed bottom of melting pot at original content of tungsten hexafluoride in gas mixture 45-50 wt %, which is tapered gradually up to 30 wt. %. At the second stage the mixture of tungsten hexafluoride and hydrogen is supplied to the chamber top-down parallel to formed walls of melting pot with content of tungsten hexafluoride in the mixture 28-30 wt %. The first stage is implemented up to achieving of tungsten sediment weight ΔP₁ defined for specified geometry of melting pot according to expression: ΔP₁≥π/2 x (s₁-s₂) x (D² ₁/2 + hD₂) x γ_w, where: ΔP₁ - tungsten sediment weight, recived at the first stage of process with supplying of gas mixture bottom-up; s₁ - defined thickness of tungsten layer on the bottom of melting pot; s₂ - defined thickness of tungsten layer on top edge of side wall of melting pot; D₁ - effective diametre of sediment on the bottom of melting pot formed at the first stage of the process, equal to the diametre of base at the bottom plus double difference (s₁-s₂); D₂ - effective diametre of base on the side wall, equal to half of diametres sum of base at the bottom and on the top edge of melting pot; h - defined height of melting pot; γ_w - tungsten density, which is 19.3 g/cm³. Copper base is removed by resolution in nitric acid. Then it is implemented mechanical operation of melting pot workpiece blank.

EFFECT: heavy melting pots made of tungsten, allowing high density and strength.

7 cl, 1 dwg, 1 ex