Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Post sintering operation
Patent
1983-09-23
1986-03-11
Lechert, Jr., Stephen J.
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Post sintering operation
419 28, 419 29, 419 47, 419 57, 264 56, 264 65, 264332, B22F 300
Patent
active
045754497
ABSTRACT:
The present invention discloses a method for densifying previously sintered parts constructed of powdered metals, ceramics or the like to nearly 100% theoretical density. The method of the present invention comprises heating the parts containing binder and hard phase above their liquid phase temperature and then applying a pressure in a predetermined range to the parts for a predetermined period of time and simultaneously maintaining the parts at or above their liquid phase temperature. This pressure range is set so that the pressure is below the pressure necessary to overcome the capillary force acting on the binder to keep the binder from entering the voids but above the pressure necessary to physically move or collapse themicrostructure inwardly, thus filling the voids with a homogeneous mixture of binder and hard phase. The method of the present invention achieves complete closure of even large voids and the elimination of substantially all porosity within the part.
REFERENCES:
patent: 2263520 (1941-11-01), Romp
patent: 3937630 (1976-02-01), Kimura et al.
patent: 4431605 (1984-02-01), Lueth
Pages 6 and 64 of San Sonov G.V. Hot Pressing Technology in the Soviet Machine Building and Metallurgical Industries.
Goetzel Treatise on Powder Metallurgy, vol. 1949 (pp. 424-425).
Lechert Jr. Stephen J.
Ultra-Temp Corporation
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