| 摘要 |
<p>A method is disclosed of making sintered parts with cryogenically-produced powder derived from scrap metal, such as machine turnings. The scrap metal is subjected to two impacting operations (such as by use of a ball milling machine). The first operation is carried out with the use of a refrigerating agent (to lower the temperature of the scrap metal below its ductile-brittle transition temperature) thereby resulting in comminution of the scrap to a cryogenic powder. 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; simultaneously, copper is mechanically transferred to substantially each particle of said cryogenic powder to form a continuous copper envelope thereabout. The coated cryogenic powder is then compacted and sintered; the sintered product may be subjected to hardening or tempering treatments if desired.</p> |
