Quasi-containerless glass formation method and apparatus
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsRobert J. Naumann, Edwin C. Ethridge
Life of this patent
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Abstract
Apparatus and method for forming ultrapure glass rods (13) or fibers (28) from a polycrystalline rod (11) in which the method comprises the steps of heating a selected short section of the rod in the first furnace (21) to form a molten zone of the rod, heating a second selected short section of the rod in a second furnace (19) which initially is separated from the first furnace by a very short gap to form a second molten zone of the rod which initially is contiguous with and part of the first molten zone of the rod to form a single molten zone 14, and then gradually moving the first and second furnaces apart to first form a rod (13) and then, ultimately, a fiber (28), of ultrapure glass in the increasingly widening gap forming therebetween.
Claims17
A method of forming a glass rod from a precursor rod comprising performing in a microgravity environment the steps of:
- heating a selected short section of said precursor rod in a first furnace to form a first self-supporting molten zone therein;
- heating a second selected short section of said precursor rod in a second furnace to form a second self-supporting molten zone of said rod which initially is contiguous with and part of said first molten zone;
- gradually moving said first and second furnaces apart to form an extended molten zone;
- and
- cooling the central portion of the extended molten zone at a sufficient cooling rate to a temperature below the glass transition temperature to form a rod of glass in the increasingly widening gap forming therebetween.
A method of preparing a glass rod from a reluctant glass--forming composition which comprises:
- preparing a precursor rod comprising a first axial section formed of a good glass former, a second axial section formed of a reluctant glass former and a third axial section between said first and second sections formed of a transitional composition gradually changing from a good glass former to a reluctant glass former;
- heating a short portion of said precursor rod at said first section in a furnace disposed in a microgravity environment to form a molten zone;
- moving said rod and said furnace relative to one another to gradually move said rod through said furnace and thereby move said molten zone through said second and third sections along said rod and cooling the area of said rod behind said molten zone to a desired undercooling temperature at a desired rate so as to produce glass from said reluctant glass-forming composition, said moving and cooling steps being performed in a microgravity environment.
Apparatus for making a rod of glass from a glass precursor rod in a microgravity environment comprising:
- a first furnace for heating a first short section of said glass precursor rod to a first melted state zone;
- a second furnace for heating a second short section of said glass precursor rod adjacent to said first short section of rod to a second melted state zone which is contiguous to said first melted state;
- and
- means for gradually separating said first and second furnaces along with said first and second melted state zones to leave an increasingly longer molten zone adapted to be cooled to form a rod of glass in between said separating melted state zones.
Dependencies are inferred from the claim text.