Study of Influence of Zinc Plated Mild Steel Deterioration in Seawater Environment

摘要

The corrosion resistance of electrolytic zinc-coating on mild steel in seawater was investigated. Mildudsteel samples were zinc electroplated at voltage varied (0.6, 0.8, 1.0, 1.5 V) and for plating time alsoudvaried (20, 30, 40, 50, 60 minutes). Focused ion-beam scanning electron microscopy was used toudobserve the surface morphology of the plated surface. The visual observation of plated samplesudrevealed that samples plated at 0.6 V for 20 and 60 minutes; 0.8 V for 30 minutes and 1.0 V for 40udminutes showed the best physical properties such as colour, brightness, fineness, streak and strongudadhesion. The plated samples were then subjected to seawater environment for 30 days. The electropotentials mV (SCE) was measured daily. Weight loss was determined at intervals of five days for theudduration of the exposure period. Experimental result showed little corrosion attack on the zinc-platedudsamples on the fifteenth and twenty-fifth day’s exposure. The severity of attack decreases withudincreasing weight of zinc coated on substrate. Significant increases in the corrosion resistance wereudachieved for the plated samples compared with that of the substrate. The pH of the seawater becameudmore alkaline at the end of the thirty days test.