Abstract: A sintering furnace includes an upper housing having a gas permeable insulating enclosure therein, with heating elements within the enclosure, and a lower housing having a hearth against which the insulating enclosure rests. Sweep gas is introduced to the interior of the upper housing, outside of the insulating enclosure. The sweep gas flows through the porous enclosure, past the pieces being sintered to sweep organics away, and out of the enclosure through an organics sink post extending upwardly from the hearth. The sink post is hollow and has openings therein, and is in communication with an external trap and vacuum pump, so that the organic-laden sweep gas is drawn out of the furnace. The insulating enclosure includes a gas barrier having openings therethrough and insulation layers on either side, the openings being sized such that the flow of sweep gas prevents diffusion of organic vapor out of the enclosure into the upper housing.
Type:
Grant
Filed:
July 12, 1989
Date of Patent:
September 17, 1991
Assignee:
Risi Industries
Inventors:
Kenneth P. Johnson, Charles A. Zwissler
Abstract: Provided is a method of manufacturing sintered parts from particulate material, e.g metal or ceramic parts. The method comprises mixing together predetermined amounts of powdered particulate material and a binder, which mixture is then molded under heat and pressure. The binder comprises at least a lower melting point component and a higher melting point component, with the lower melting point component remaining in a liquid state, becoming semi-solid or relatively soft upon cooling to ambient temperatures. Prior to sintering, the lower melting point component of the binder is selectively dissolved in a liquid solvent, and the higher melting point component is removed upon heating at temperatures below the sintering temperature. The result is a process which eliminates or prevents the formation of oxides, substantially reduces the time required for debinding and sintering, and essentially eliminates cracking in the finished part.