摘要 |
Powder flow in an apparatus for growing crystals according to the process of Verneuil, whereby powder falls downwardly into a flame impinging on and melting a surface of a seed crystal, is made uniform by isolating the powder supply container from oscillations in the air column beneath the container induced by vertical movements of a screening grid in the apparatus. Isolation is effected by a rotating sphere in a flow tube of the apparatus between the supply container and the oscillating screen, the sphere having close tolerances to the wall of the tube and vertical grooves in its periphery. The vertical grooves and the sphere surface also can meter the falling powder. |