Temperature gradient furnace for materials processing
AssigneeGrumman Aerospace Corporation
InventorsRobert Haslett, William Harwell
Life of this patent
Estimating the term…
Abstract
A cylindrically hollow segmented thermal gradient furnace enclosing metal or semiconductor material wherein each segment includes a heater for raising the temperature of the metal. The material is encircled by a heat pipe which is coupled to a heat exchanger for rapidly cooling a corresponding segment of the material after the heater has performed a thermal soak of the material. A reservoir is filled with inert gas which is selectively expanded to block cooling at the heat exchanger when the heater is turned on and compressed to allow cooling at the exchanger when the heater is turned off so that a sharp thermal gradient may be established along the length of the material.
Claims11
A thermal gradient furnace having a plurality of axially adjacent independently controlled segments, each segment comprising:
- a material container positioned axially;
- an annular support for mounting at least one heat pipe therearound and coaxially enclosing the container;
- heat exchange means thermally connected to the heat pipe for cooling the furnace and consequently the material;
- means connected to the heat pipe for selectively blocking thermal conductance between the heat exchange means and the pipe thereby preventing cooling of the material;
- heating means encircling the container for selectively heating the material therein;
- thermal sensing means located in proximity to the material container for sensing thermal conditions in the furnace;
- and
- preprogrammed means connected at its input to the sensing means and at individual outputs to the conductance blocking means and the heating means for controlling heating and cooling cycles of each segment thus creating a sharp thermal axial gradient along the length of the material.
A method for creating sharp thermal gradients along the length of metal or semiconductor material, comprising the steps:
- defining a plurality of contiguous axial thermal segments;
- encircling the material with at least one heat pipe thermally communicating with a heat exchanger;
- selectively expanding inert gas into the heat pipe for blocking heat exchange between fluid in the heat pipe and coolant in the exchanger when heating the material;
- thermally soaking the material for a preselected period;
- compressing the inert gas for removing it from the heat pipe thereby enabling rapid cooling of the material associated with the segment;
- preprogramming the cooling cycles for each segment to create sharp thermal gradients along the entire length of the material.
Dependencies are inferred from the claim text.