| 摘要 |
<p>PURPOSE:To obtain cast iron powder for powder metallurgy for producing a wear resistant ferrous sintered allay by forming the structure of a matrix of powder having a specified compsn. constituted of C, Si and Fe of a specified one in which lumpy graphite is dispersed and forming its surface into a one coated with precipitated graphite. CONSTITUTION:Molten metal constituted of, by weight, 2.5 to 5% C and 0.2 to 2% Si and furthermore constituted, at need, of <=0.5% Ce, and the balance Fe with inevitable impurities is subjected to atomizing by high pressure water to obtain powder having a ledeburite structure. This powder is annealed at about 700 to 1050 deg.C in a nonoxidizing atmosphere to graphitize cementite. In this way, the cast iron powder for powder metallurgy in which, in the matrix of powder, lumpy graphite is dispersed into a ferritic structure or a mixed structure of ferrite and pearlite or a pearlitic structure and the surface of the powder is coated with precipitated graphite is obtd. This cast iron powder is compacted and is sintered in a nonoxidizing atmosphere, by which the wear resistant ferrous sintered allay low in a friction coefficient and excellent in seizing resistance can be obtd.</p> |
