Methods and Apparatus for Manufacturing and Printing Hollow Spheres

A method of forming hollow spheres from an amorphous material comprising:

• providing an amorphous material having a temperature-dependent viscosity;
• providing a source of a gas;
• flowing a stream of the gas coaxially through a flow of the amorphous material to form at least one hollow sphere having the gas disposed therein;
• depositing the at least one hollow sphere onto a base plate surface such that the at least one hollow sphere free falls for a sufficient time to generate a target kinetic energy in the at least one hollow sphere, wherein the kinetic energy on impact with the surface is sufficient to deform the at least one hollow sphere without rupture;
• and
• repeating the deposition of a plurality of hollow spheres layer-by-layer to form a three dimensional object therefrom.

An apparatus for forming hollow spheres from an amorphous material comprising:

• a heatable amorphous material reservoir having upper and lower ends and defining a heatable inner volume, and wherein the lower end has a amorphous material outlet formed therein;
• at least one gas conduit in fluid communication with a gas supply and having a gas outlet disposed at one end thereof, the gas outlet being disposed substantially coaxially within the amorphous material outlet;
• at least one amorphous material conduit defined by a gap between an inner wall of the amorphous material outlet and an outer wall of the gas outlet, and being in fluid communication with the inner volume of the heatable amorphous material reservoir;
• wherein at least a portion of the at least one gas conduit is vertically movable within the apparatus and configured such that a vertical movement of the gas conduit alters the volume of a flow of the fluid amorphous material through the at least one amorphous material conduit from a closed state wherein a portion of the gas conduit seals against a portion of the amorphous material conduit to prevent the fluid amorphous material from flowing through the amorphous material outlet, to an open configuration wherein the fluid amorphous material disposed within the heatable amorphous material reservoir flows through the at least one amorphous material conduit to the amorphous material outlet;
• wherein the gas and liquid outlet are configured such that gas flowing through the outlet is entrained within the flow of the fluid amorphous material as one or more hollow spheres at the liquid outlet;
• wherein the vertical movement of the gas conduit causes a concomitant movement in the vertical position of the gas outlet relative to the amorphous material outlet, such that the width of the gap forming the amorphous material conduit, and thereby the volume of a flow of the fluid amorphous material is adjustable from a closed state wherein the outer wall of the gas outlet presses against the inner wall of the amorphous material outlet, to an open configuration such that a fluid amorphous material disposed within the heatable amorphous material reservoir flows through the at least one amorphous material conduit to the amorphous material outlet;
• wherein the change in the amorphous material conduit from the open to the close state is configured to occur sufficiently rapidly to allow for the formation of a single hollow sphere;
• wherein the width of the gap in the open state is variable such that the thickness of the walls of the one or more hollow spheres is variable;
• wherein the diameter of the liquid outlet is variable such that the diameter of the one or more hollow spheres is variable;
• wherein the relative vertical position of the gas outlet within the liquid outlet is adjustable by rotating the gas conduit within the apparatus;
• wherein an amorphous material disposed within the inner volume is selected from the group consisting of glass compositions, silicate glasses, metallic glasses, ceramic glasses, and composite materials with an amorphous phase and amorphous or crystalline inclusions;
• wherein the liquid outlet is annular;
• further comprising a base plate disposed in line with the liquid and gas outlets;
• wherein the distance between the base plate and the liquid and gas outlets is such that the hollow sphere formed at the liquid outlet reaches terminal velocity while falling;
• wherein one or both the lower end of the heatable liquid material reservoir and the base plate are moveable relative to each other in at least three dimensions;
• further comprising a cooling element disposed between the liquid outlet and the base plate;
• wherein the viscosity of the hollow sphere at the base plate is from 2 Pa-s to 10{circumflex over ( )}8 Pa-s;
• wherein the outlet and the base plate are moveable relative to each other at a velocity greater than or equal to the product of the diameter of the hollow sphere and a hollow sphere production rate for the apparatus at that diameter;
• wherein multiple of the apparatus are disposed above the base plate;
• further comprising at least one conventional additive manufacturing apparatus disposed above the base plate;
• and
• wherein the at least one conventional additive manufacturing apparatus is configured to deposit a support material.