| 摘要 |
PURPOSE:To obtain high purity Cr suitable especially for sputter target, etc., and having low contents of C, O, N, S, by adding rare earth element into molten Cr in vessel composed of calcia quality furnace material, under vacuum or Ar atmosphere. CONSTITUTION:Rare earth element is added, into molten Cr, under vacuum or Ar atmosphere, in vessel in which the inner surface is composed of calcia quality furnace material. Quantity of the rare earth element in molten Cr is favorable to control to about 10-1,000ppm, especially to about 50-300ppm. After addition of rare earth element, through stirring is favorable. By existence of rare earth element (denoted as R), since, O, S mixed in molten metal are converted to RO, R2O, RO2, RS, etc. or CaS, contents of O, S are decreased extremely. Further, molten metal having scarce residual rare earth element being adding material for removing O, S, etc. is obtd. N quantity in molten metal is decreased as the lapse of time. |
