Inhibition of corrosion of mild steel hull plates immersed in natural sea water by sandalwood oil extract of some natural products

Abstract

The hull plates of the ship made of mild steel (MS) are always in contact with sea water are always in contact with aggressive ions such as chloride ions present in sea water.The corrosion resistance of the hull plates of the ship made of mild steel has been investigated by polarization study. Sandalwood oil extract containing 5 g each of Cardamom (disambiguation), Clove (disambiguation), Nutmeg, India Sambrani (loban), Chrysopogon zizanioides, commonly known as vetiver and Camphor was used as corrosion inhibitor along with Trisodium citrate (TSC), sodium dihydrogen phosphate (SDP) and Zn2+. The corrosion resistance was measured in the absence and presence of various inhibitor systems: Trisodium citrate (TSC) 100 ppm+ Zn2+ 50ppm system, sodium dihydrogen phosphate (SDP) 100 ppm+ Zn2+ 50ppm system, Oil coated (3days) MS, Oil coated (3days) MS +TSC 100 ppm+ Zn2+ 50 ppm system and Oil coated (3days) MS +SDP100 ppm+ Zn2+ 50 ppm system were used. It is observed that when mild steel is immersed in SW+TSC 100 ppm+ Zn2+ 50ppm system, the corrosion resistance of MS increases. When mild steel is immersed in SW+ SDP 100 ppm+ Zn2+ 50ppm system, the corrosion resistance of MS increases. When mild steel is immersed in Oil coated (3days) MS in Sea water system, the corrosion resistance of MS increases. When mild steel is immersed in Oil coated (3days) MS in SW+TSC 100 ppm+ Zn2+ 50ppm system, the corrosion resistance of MS increases. When mild steel is immersed in Oil coated (3 days) MS in SW+ SDP 100 ppm+ Zn2+ 50ppm system, the corrosion resistance of MS increases. This is revealed by the fact that there is increase in LPR value and decrease in corrosion current value. The corrosion potential is shifted to anodic side. This indicates that in this inhibitor system, the anodic reaction of metal dissolution is controlled predominantly. This implies that these inhibitor systems may be coated on mild steel surface used as hull plates to prevent corrosion of mild steel in sea water.