Turning to nanotechnology, a group of marine researchers from Kerala is attempting to combat corrosion of steel used for making fishing boats. Corrosion of steel has been a major cause of concern for the fishing sector of Kerala where steel vessels have almost replaced wooden ones.
There is enhanced threat of corrosion in the case of welding joints and the hull of a vessel. The non-availability of good quality steel (BIS 2062 Grade B steel) as specified for boat-building has compounded the problem.
Scientists at the Central Institute of Fisheries Technology (CIFT), Kochi, have successfully tried applying nanomaterials like nano iron oxide, zinc oxide, cerium oxide and titanium oxides on steel surfaces under lab conditions. According to Dr. C.N. Ravishankar, director of the institute, these nanomaterials have high surface area and increased adhesiveness to the substrate. According to Dr. P. Muhammed Ashraf, Principal Scientist at CIFT, who led the research programme, the boat-building steel was coated with nano-trimetal oxide mixtures, and its evaluation in laboratory showed about 40% corrosion inhibition under marine environments. He said that the coating also exhibited healing stress at a faster rate.
Conventional methods of coating of steel materials with ceramic, polymeric and electro-deposition are effective only to a limited extent. Corrosion-protection methodologies usually employ organic or inorganic-based coatings on steel. The researchers pointed out that the major disadvantages shown by these coatings are poor adhesion, coating defects, poor scratch resistance, optical transparency, low coating flexibility and vulnerability to abrasion.
Even the recently introduced nanomaterial-incorporated polymer coatings have their own set of challenges — they tend to develop pinholes and pores, which could lead to the penetration of corrosive agents into the matrix followed by corrosion.
