Ceramic coatings by sol-gel method for corrosion protection of mild steel

Abstract

Mild steel finds extensive applications in automobile, household appliances, heavy construction and business machines due to its mechanical properties and machinability at low cost. However, it is prone to corrosion that leads to industrial accidents and loss of material resources. Sol-gel derived ceramic coatings have been deposited on mild steel (MS) with a prior conversion coating for its corrosion protection. The prior conversion coating led to the formation of well adherent coatings of Al2O 3 , ZrO 2 and TiO 2 . The Scanning Electron Microscope (SEM), X-ray diffractometer (XRD) and FT-IR was used to study the morphology, phases formed and nature of bonding in the coating. The electrochemical corrosion behavior of the coated MS was evaluated in 3.5 wt.% NaCl solution. The coatings show barrier type protection of MS up to about 1 V SCE . The Al 2 O 3 and ZrO 2 coatings were observed unaffected during prolong immersion in 3.5 wt.% NaCl solution. The physicochemical and electrochemical properties have been correlated and discussed.