| 摘要 |
<p>An improved, economical method of converting scrap metal, particularly machine turnings, to a powder having useful characteristics for warm or hot powder forming techniques, is disclosed. Cryogenic processing is employed in which machine turnings are cooled to below their ductile-brittle transition temperature by the use of liquid N2; copper ball milling elements are employed as multiple function elements: fragmentizers, cold-working elements and coating elements. The resulting mass of liquid N2 and metal pieces are circulated so that in one zone a true slurry exists with a liquid N2 in intimate contact with the metal piece, and in another zone the metal pieces are withdrawn from the slurry to momentarily increase in temperature.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 copper coating of the comminuted particles occurs in both zones.</p> |
