Removal of zinc layers from coated steel strip by thermal and mechanical processing

In this research project, basic investigations on the low temperature react ions of the zinc coating layer with the iron substrate were performed in or der to develop novel methods for zinc removal from scrap material by baking the material at a moderate temperature to produce brittle intermetallic co mpounds, which may be subsequently removed under mechanical load, for insta nce by shredder treatment. The investigations have shown that it is possibl e to prepare a fragile Fe/Zn-intermetallic layer on the substrate by proper baking of the material at moderate temperatures. Mechanical working remove s zinc from the strip substrate. The plane of cleavage is the phase boundar y between the delta- and the Gamma-compound. A precise control of the heati ng cycle adjusted to the layer thickness is mandatory to attain an effectiv e zinc removal. This requirement is difficult to meet in the operation of a n industrial installation.