Влияние катодного внедрения хрома в цинковое покрытие на его защитную способность

Abstract

The influence of cathodic introduction of chromium into the surface layers of a zinc coating on the change in its corrosion resistance has been determined. Electrodeposition of zinc from electrolytes of various compositions was carried out on electrodes made of St3 steel. TsO grade zinc was used as an anode. Preliminary steel electrode was preparated treating the steel surface of in the potentiostatic mode of pre-phase deposition (DPD) at a potential 50 mV more positive than the equilibrium potential of zinc (Ep) in the working electrolyte for 5 minutes. The zinc coating was applied in potentiostatic mode at a potential of –1.20 V relative to the silver chloride reference electrode. The introduction of chromium into the electrodeposited zinc coating was carried out in the potential range from –0.97 to –1.15 V from electrolytes containing trivalent chromium salt. The results of X-ray fluorescence analysis of the component composition of working electrodes after cathodic introduction of chromium, the morphology of the formed surface obtained using scanning electron microscopy, indicate the presence of chromium in the coating composition and its effect on the structure of the deposit. The corrosion resistance of modified zinc coatings by cathodic introduction of chromium at potentials of –1.05 V and –1.10 V for 5 minutes exceeds this characteristic of chromated zinc.