Apparatus for silica crucible manufacture

Abstract

An apparatus for manufacture of quartz crucibles comprising a hollow mold having a bottom wall portion and a side wall portion and defining a hollow space therein. The walls of the mold include a plurality of openings to facilitate gas passage therethrough. A rotatable support of the mold is provided to rotate the mold about a vertical axis. A vacuum is applied through the walls of the mold to draw quartz particles against the walls and remove gas. A shroud surrounds at least a portion of the hollow mold; at least one gas inlet positioned to provide a gas to a space between the shroud and the mold. A housing overlaps at least a portion of the shroud and the hollow mold. At least one gas outlet is positioned to exhaust gas which may exit the space between the shroud and the mold. Alternatively, or in addition to the outlet, a space may be provided between the housing (hood) and the shroud to facilitate gas discharge. In manufacturing a crucible in this apparatus, the gas flow can be balanced so the in-flow rate of control gas is in excess of the exhaust rate from the controlled atmosphere via the outlet or space.