Cabot Corporation

Ronald D Rivers

Prabhat Kumar

Anthony J Hickl

A powder metallurgical process for producing a wrought product characterized by a low level of residual impurities. The process comprises the steps of: comminuting metal powder to effect a reduction in particle size, at least 60% of the comminuted particles being capable of passing through a -270 mesh Tyler screen; blending the metal powder with a softer metal-bearing powder; heating the blended powder particles at an elevated temperature, the particles adhering and forming a mass during heating; crushing the mass of powder particles; cold-isostatically pressing the crushed mass of powder; sintering the powder in the absence of an encapsulating member under conditions which effect a reduction in the nitrogen, oxygen and carbon levels of the powder; and hot working the sintered powder into a wrought product. The wrought product has less than 0.015% carbon.

Wrought P/M processing for master alloy powder

A process for producing a wrought product of improved ductility from substantially noncompactible prealloyed metal powder. The process comprises the steps of: comminuting substantially noncompactible prealloyed metal powder so as to flatten the particles thereof; heating the comminuted particles of metal powder at an elevated temperature, the particles adhering and forming a mass during heating; crushing the mass of metal powder; compacting the crushed mass of metal powder; sintering the metal powder; and hot working the metal powder into a wrought product. The wrought product has a chemistry which is substantially the same, with the exception of carbon and certain residuals, as the chemistry of the prealloyed powder.

Wrought P/M processing for prealloyed powder

A method for improving the compaction characteristics of a substantially noncompactable metal powder comprising preparing a superalloy, for example, a nickel base alloy, minus a portion of at least one metal (i.e., 5 weight percent); atomizing the melt and milling it to a fine powder (i.e., about average Fisher size of 9.0 microns); blending an equal portion (i.e., about 5 weight percent) of, for example, carbonyl nickel into the milled powder; sinterbonding the mixture into a 'cake' and then further processing as may be required to obtain the desired article. It is believed the 'soft' carbonyl nickel acts as a binder for the prealloyed nickel-base alloy powder.

Metal binder in compaction of metal powders

Parts are formed from metal powder by mixing the powder with a plastic medium comprising an organic binder dissolved in a solvent in which it is soluble at room temperature but in which it is substantially less soluble at a higher temperature such that the plastic binder becomes viscous at that temperature. Binder modifiers may be incorporated to promote mold release and promote healing of interfaces within the molded part and prevent the formation of drying cracks. The plastic mixture is injected under pressure into a closed die preheated to the above mentioned higher temperature, whereby the rejection of solvent and increase in viscosity of the plastic medium produces a compact sufficiently self-supporting to hold its molded shape and be ejected from the die. The compact is then dried to evaporate the remaining solvent, thus leaving interconnecting pores in the compact for the escape of gases resulting from subsequent burning out of the binder during the sintering operation.

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Kokomo, IN, United States of America

Ronald D Rivers