Specialized metallurgical processes – compositions for use therei – Compositions – Consolidated metal powder compositions
Patent
1976-10-26
1978-12-12
Schafer, Richard E.
Specialized metallurgical processes, compositions for use therei
Compositions
Consolidated metal powder compositions
75200, 75211, 75213, 75214, 75224, 241 23, 241DIG37, 264111, 427 11, 427216, 427217, 427242, B22F 102, B02C 1108
Patent
active
041294432
ABSTRACT:
Methods are disclosed for embrittling scrap metal for comminution and for subsequent or simultaneous treatment of the comminuted metal powder to improve sintering kinetics and prevent oxidation of alloying ingredients. A first embrittling method impacts the scrap metal at a temperature below its ductile-brittle transition temperature to cryogenically provide scrap metal powder. The scrap metal is subjected to two impacting operations (such as by use of a ball milling machine), the first operation being carried out simultaneously with the cryogenic medium and the second impacting operation is carried out at ambient temperature conditions utilizing milling elements which impart cold work to at least a portion of the cryogenic powder. An anti-oxidation agent, such as copper or iron, is mechanically transferred to substantially each particle of said cryogenic powder during the second operation to form a continuous copper or iron envelope thereabout. The coated cryogenic powder is then compacted and sintered; the sintered product may be subjected to hardening or tempering treatments if desired. Also disclosed is a continuous method for carrying out both cryogenic embrittlement impaction, and coating. A mass of liquid N.sub.2 and metal pieces are circulated in a properly oriented tube so that in one zone a true slurry exists with liquid N.sub.2 in intimate contact with the metal pieces; in another zone the metal pieces are withdrawn from the slurry to momentarily increase in temperature. Fragmenting occurs substantially in said one zone and cold-working substantially in said another zone, while progressive anti-oxidation coating of the comminuted particles occurs in both zones.
A second embrittling method involves dissolving the carbon in ferrous scrap metal having a critical predetermined carbon content, quenching the metal to produce substantially all martensite, and impacting the treated metal while simultaneously coating with an anti-oxidizing agent.
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Ford Motor Company
Johnson Olin B.
Malleck Joseph W.
Schafer Richard E.
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