Abstract: A multizone convection furnace is provided in which gas from a cooling chamber of the furnace is directed into one or more heat zones of the furnace for the purpose of providing a specified thermal profile. The gas introduced from the cooling chamber into the one or more heat zones is of the same type of gas present in the heat zones, and typically is nitrogen. In a preferred embodiment, the convection furnaces comprises a heating chamber composed of a plurality of adjacent heat zones and a cooling chamber at the exit end of the heating chamber. A conveyer extends through the furnace for movement of a product through the heat zones and cooling chamber of the furnace. The cooling chamber is coupled to one or more of the heat zones such that cooled gas from the cooling chamber can be introduced into selected heat zones. In one version, a cooled gas path is provided to all of the heat zones and cooled gas is introduced into intended zones by opening associated valves.

Abstract: The present invention provides a method for conveniently manufacturing a solid oxide fuel cell (SOFC) at a cost that is less than five-hundred dollars per kilowatt of electricity. The method comprises forming an electrode layer and depositing an electrolyte material on the surface of the electrode. The formed structure is an electrode-electrolyte bi-layer. A second electrode is deposited onto this bi-layer to form a multilayer fuel cell structure comprising an electrolyte positioned between two electrodes. This multilayer structure is then heated and fired in a single thermal cycle to remove any binder materials and sinter, respectively, the fuel cell. This thermal cycle can be performed in a furnace having one or more chambers. The chamber(s) preferably contains a variable or multiple frequency microwave source for heating the cell and removing binder materials in the electrolyte and electrode structures. The chamber(s) also preferably include a convection and/or radiation source for sintering the fuel cell.

Abstract: In a system for thermally processing materials, at least one slot eductor is disposed in a wall or roof surface of the furnace chamber to provide circulation of gas within the furnace chamber.

Abstract: The present invention provides a system and method for binder removal and sintering of materials such as ceramic materials and products, LTCC intervals, solid oxide fuel cells and powder metals. A combination of microwave and convection/radiation heating is employed for binder removal and sintering. Preferably, the microwave heating is accomplished using a variable or multi-frequency microwave source. A gas atmosphere is provided in the furnace chamber by one or more eductors which produces a high volume gas circulation in the furnace chamber to achieve a highly uniform gas environment and temperature. The process in accordance with the invention controls the heating cycle, the heat sources and thermal profile depending upon the composition of the particular material being processed. The thermal processing can be accomplished in a batch furnace in which a product is loaded for processing and unloaded after processing.

Abstract: In a system for thermally processing materials, at least one slot eductor is disposed in a wall or roof surface of the furnace chamber to provide circulation of gas within the furnace chamber.

Abstract: The present invention provides a method for conveniently manufacturing a solid oxide fuel cell (SOFC) at a cost that is less than five-hundred dollars per kilowatt of electricity. The method comprises forming an electrode layer and depositing an electrolyte material on the surface of the electrode. The formed structure is an electrode-electrolyte bi-layer. A second electrode is deposited onto this bi-layer to form a multilayer fuel cell structure comprising an electrolyte positioned between two electrodes. This multilayer structure is then heated and fired in a single thermal cycle to remove any binder materials and sinter, respectively, the fuel cell. This thermal cycle can be performed in a furnace having one or more chambers. The chamber(s) preferably contains a variable or multiple frequency microwave source for heating the cell and removing binder materials in the electrolyte and electrode structures. The chamber(s) also preferably include a convection and/or radiation source for sintering the fuel cell.

Abstract: The present invention provides a system and method for binder removal and sintering of materials such as ceramic materials and products, LTCC intervals, solid oxide fuel cells and powder metals. A combination of microwave and convection/radiation heating is employed for binder removal and sintering. Preferably, the microwave heating is accomplished using a variable or multi-frequency microwave source. A gas atmosphere is provided in the furnace chamber by one or more eductors which produces a high volume gas circulation in the furnace chamber to achieve a highly uniform gas environment and temperature. The process in accordance with the invention controls the heating cycle, the heat sources and thermal profile depending upon the composition of the particular material being processed. The thermal processing can be accomplished in a batch furnace in which a product is loaded for processing and unloaded after processing.

Abstract: A multizone convection furnace is provided in which gas from a cooling chamber of the furnace is directed into one or more heat zones of the furnace for the purpose of providing a specified thermal profile. The gas introduced from the cooling chamber into the one or more heat zones is of the same type of gas present in the heat zones, and typically is nitrogen. In a preferred embodiment, the convection furnaces comprises a heating chamber composed of a plurality of adjacent heat zones and a cooling chamber at the exit end of the heating chamber. A conveyer extends through the furnace for movement of a product through the heat zones and cooling chamber of the furnace. The cooling chamber is coupled to one or more of the heat zones such that cooled gas from the cooling chamber can be introduced into selected heat zones. In one version, a cooled gas path is provided to all of the heat zones and cooled gas is introduced into intended zones by opening associated valves.

Abstract: A continuous pusher furnace includes a product carrier assembly incorporating a traveling gas barrier. The product carrier assembly comprises a plate disposed to receive product thereon and a gas barrier extending upwardly from the plate. The perimeter of the gas barrier is sized and configured to fit within a vestibule between heating chambers in the furnace with a clearance gap with the vestibule selected to increase a gas flow velocity through the vestibule sufficient to overcome a gas diffusion velocity through the vestibule in a direction opposite to the gas flow. In this manner, gas is unable to diffuse into an upstream heating chamber. In an alternative embodiment, an exhaust outlet may also be provided in the vestibule or chamber to exhaust gas from upstream and downstream heating chambers from the furnace.

Abstract: A continuous pusher furnace includes a product carrier assembly incorporating a traveling gas barrier. The product carrier assembly comprises a plate disposed to receive product thereon and a gas barrier extending upwardly from the plate. The perimeter of the gas barrier is sized and configured to fit within a vestibule between heating chambers in the furnace with a clearance gap with the vestibule selected to increase a gas flow velocity through the vestibule sufficient to overcome a gas diffusion velocity through the vestibule in a direction opposite to the gas flow. In this manner, gas is unable to diffuse into an upstream heating chamber. In an alternative embodiment, an exhaust outlet may also be provided in the vestibule or chamber to exhaust gas from upstream and downstream heating chambers from the furnace.

Abstract: A continuous pusher furnace includes a product carrier assembly forming a traveling gas barrier. The product carrier assembly comprises a pusher plate disposed to receive product thereon and a gas barrier extending upwardly from the pusher plate. The perimeter of the gas barrier is sized and configured to fit within a vestibule between heating chambers in the furnace with a clearance gap with the vestibule selected to increase a gas flow velocity through the vestibule sufficient to overcome a gas diffusion velocity through the vestibule in a direction opposite to the gas flow. In this manner, gas is unable to diffuse into an upstream heating chamber. In an alternative embodiment, an exhaust outlet may also be provided in the vestibule or chamber to exhaust gas from upstream and downstream heating chambers from the furnace.

Abstract: A high-temperature conveyor furnace with a low friction conveyor travel surface is provided. The furnace includes a muffle defining a heating chamber, hearth plates providing a hearth surface within the heating chamber, and a conveyor belt to convey product through the heating chamber. The conveyor belt is formed of a first material, such as a nickel-chrome alloy. A plurality of low-friction inserts are supported by the hearth plates, preferably in openings in the hearth plates, to provide a surface upraised from the hearth surface upon which the conveyor belt travels. The inserts are formed of a second material, such as an electronics grade ceramic, that is different from the first material of the conveyor, which minimizes friction between the inserts and the belt. The low-friction surface is particularly suitable for high temperature, low dewpoint furnace applications, such as stainless steel brazing.