US 12,257,629 B2
Apparatus and methods for sintering
Kurt Heikkila, Marine on the Saint Croix, MN (US); and Rodney Williams, Stacy, MN (US)
Assigned to Tundra Compoistes, LLC, White Bear Lake, MN (US)
Appl. No. 17/315,607
Filed by Tundra Composites, LLC, White Bear Lake, MN (US)
PCT Filed Dec. 7, 2020, PCT No. PCT/US2020/063576
§ 371(c)(1), (2) Date May 10, 2021,
PCT Pub. No. WO2021/141704, PCT Pub. Date Jul. 15, 2021.
Claims priority of provisional application 62/959,168, filed on Jan. 9, 2020.
Prior Publication US 2023/0234127 A1, Jul. 27, 2023
Int. Cl. F27B 21/00 (2006.01); B22F 3/00 (2021.01); F27B 9/36 (2006.01); F27D 11/06 (2006.01); F27D 11/12 (2006.01); B33Y 40/20 (2020.01); F27D 99/00 (2010.01)
CPC B22F 3/003 (2013.01) [F27B 9/36 (2013.01); F27B 21/00 (2013.01); F27D 11/06 (2013.01); F27D 11/12 (2013.01); B33Y 40/20 (2020.01); F27D 2099/0015 (2013.01); F27D 2099/0028 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A furnace for sintering a workpiece, the furnace comprising:
a) at least one inductor coil;
b) at least one hollow cylindrical susceptor enclosing a process tube and an infrared heating zone containing a reducing atmosphere, the susceptor comprising a material capable of absorbing electromagnetic energy from the coil to generate radiant infrared heat and to shield the heating zone from incident RF heat;
c) at least one insulating layer surrounding the susceptor; and
d) a supply of power for said coil;
wherein the process tube in the furnace is horizontally configured to maintain a flow of the reducing atmosphere to aid in sintering and remove volatiles from the furnace; the inductor coils are energized sufficiently to progressively raise the temperature of the susceptor to heat the heating zone by radiant infrared heat to an effective temperature of 800 to 1500° C. and the sintering temperature within the heating zone comprises a uniform heat distribution.