| 摘要 |
PURPOSE:To reproduce superhard alloy powder of high purity in high yields by allowing the superhard alloy to react with molten zinc in an inert gaseous atmosphere then removing the added zinc under two stages of vacuum heating. CONSTITUTION:Superhard alloy scraps and zinc are charged into a graphite crucible, and are held for a few hours at about 800-950 deg.C in an inert gaseous atmosphere to cause catalytic reaction, whereby the superhard alloy scraps are collapsed. Next, the temp. is lowered to about 700 deg.C, and the atmosphere is maintained at about 1-10Torr degrees of vacuum, then, again the temp. is elevated to about 800-900 deg.C to distil and remove about 75-90% added zinc as far as possible. Further, gaseous nitrogen is sealed in the furnace and the furnace is allowed to cool, after which the formed and consolidated conglomerate is removed. The conglomerate is then crushed to about <=10cm sizes to expose the fresh broken surfaces, after which these are charged again into the crucible, are heated to about 800-900 deg.C at about 1-10Tor degrees of vacuum and are held at these temps. for several hours, whereby the zinc is thoroughly sublimated and evaporated away. Then, gaseous nitrogen is sealed in the furnace and the furnace is allowed to cool, after which the charging is removed and is fine ground to about 100-200meshes. |
