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

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.