| 摘要 |
<p>Phosphate coatings are formed on metal surfaces e.g. sheet steel by use of a zinc phosphate composition having a low ratio Zn:P2O5 but containing relatively high contacts of CIO3 and NO3. The process results in coatings having a fine grain and high wet corrosion resistance and which are particularly suitable for immersion electro-lacquering. Solutions contain (in g/l) 0.3-1.3 Zn, 10-26 P2O5, 0.1-3 Ni, 1-6 CIO3 and 5-25 NO3. The ratio of P2O5/Zn is in the range 9-85 and the ratio of Ni/Zn in the range 0-1.5. Solutions may also include sodium nitrite or nitrobenzene sulphonate, BF<->4 or SiF<2->6 and small amounts (e.g. up to 0.5 g/l) of other cations e.g. NH<+>4, Ca, Mn, Cu, Co.</p> |
