Electrochemical obtaining of alloy coatings Zn-Fe-P from sulfate electrolytes

The present work investigates the galvanostatic obtaining of alloy coatings Zn-Fe-P from sulfate electrolytes. Cyclic voltaamogramms show that the co-deposition of zinc with phosphorus is possible only in the presence of iron ions in the electrolytic bath. The including of P in the coating occurs at iron amounts higher than 9 wt% - higher iron concentration leads to higher phosphorus amounts. Fine crystal surface structure with spherical agglomerates characteristic for the amorphous layers is obtained even of 0,5 - 2 wt% phosphorus. Entirely amorphous and uniform coatings can be practically obtained only at very thin films. Potentiodynamic curves in IN Na2SO4 show that Zn-Fe-P alloy containing up to 2 wt% P and 20 wt% Fe demonstrate better corrosion characteristics compared to Zn-Fe coatings. Key words: electrodeposition, Zn-Fe-P alloys, cyclic voltammetry