Exothermic mixt. for purifying molten aluminium:silicon alloys - contains sodium cpds., metal powder such as aluminium, and oxidants such as sodium nitrate

摘要

The mixt. contains (I) cpds. which produce Na in the molten alloys; (II) metal powders with limited reactivity in the melt; and (III) oxidants which activate metals (II). The mixt. is used for the treatment of hypoeutectic or eutectic A1-Si allys. Metal (II) is pref. powder, shot or turnings of A1; A1 alloys; Mg; Mg alloys; and/or Ca-Si alloys. Oxidants (III) are pref. alkali (ne earth) -nitrates, -chlorates, -perborates, -persulphates, -chromates, or -peroxides; or Mn02, Pb02, and/or Cr03. Cpds (I) are pref. Na2C03; Na3P04; and/or NaP207; and the mixt. may also contain NaF. The mixt. can employ coarse metal powders (II) of low cost; and only a relatively small dose of the mixt. is required for treating A1-Si alloys.