Abstract

The hollow glass vacuum microspheres are made by forming a liquid film of molten glass across the coaxial blowing nozzles, applying the metal vapor blowing gas at a positive pressure on the inner surface of the glass film to blow the film which combines with the centrifugal force to form an elongated cylinder shaped liquid film of molten glass. A transverse jet is used to direct the inert entraining fluid over and around the blowing nozzle at an angle to the axis of the blowing nozzle. The entraining fluid as it passes over and around the blowing nozzle fluid dynmically induces a pulsating or fluctuating pressure field at the opposite or lee side of the blowing nozzle in the wake or shadow of the coaxial blowing nozzle. The continued movement of the entraining fluid over the elongated cylinder produces asymmetric fluid drag forces on the cylinder and closes and detaches the elongated cylinder from the coaxial blowing nozzle and the detached cylinder by the action of surface tension forms into a spherical shape.Quench nozzles are disposed radially away from the rotor and direct cooling fluid downwardly at and into contact with the hollow glass amicrospheres to rapidly cool and solidify the molten glass to form a hard, smooth hollow glass microsphere and where metal vapor blowing gas is used to cool and condense the metal vapor and to deposit the metal vapor on the inner wall surface of the microsphere as a thin metal coating.