| 摘要 |
<p>The present invention aims at contributing to the solution of potential problems arising from the presence of ZnCl2 in the galvanizing shop, by means of a procedure for the preparation of surface of pre-fabricated steel pieces to be hot-dip galvanized in a Zn-Al-alloy, according to which the concentration of ZnC12 into the flux solution is maintained below the limit prescribed by the law and preferably down to zero. According to this procedure, the steel pieces, after pickling are immersed into an aqueous solution containing ZnCl2, NH4Cl and Bi2O3. Using the flux solution according to the present invention it is possible to coat in a batch galvanizing bath containing a Zn-Al-alloy, carbon steels and steels with high Si content, and/or Mn, and/or P (i e. steels commercially known as Sandelin or Iper-sandelin steels), usually considered difficult steels for galvanizing. obtaining coatings with uniform thickness, with no surface defects and with a smooth surface without non-homogeneous areas.</p> |
