Corrosion evaluation of nanocomposite gelatin-forsterite coating applied on AISI 316L stainless steel

In this research, AISI 316 L stainless steel was coated with layers of gelatin-forsterite nanocomposite coatings using the spin-coating technique. The effect of forsterite content, spinning speed, annealing temperature, and the number of coating layers on the corrosion behavior of AISI 316 L steel was measured by the potentiodynamic polarization. Compared with the uncoated AISI 316 L stainless steel, the results show that the nanocomposite gelatin-forsterite coatings significantly improve the uniform and localized pitting corrosion of AISI 316 L stainless steel. Nanocomposite gelatin-forsterite coatings were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive x-ray analysis (EDX). The results show a significant improvement of the surface morphology of the coated samples compared with the uncoated ones. Forsterite percentage within the suspension has an obvious influence on corrosion resistance improvement while the annealing temperature took second place regarding its effect on corrosion resistance. Moreover, the samples coated at higher spinning speed show better corrosion resistance than those coated at lower spinning speed due to the thin and uniform coating layers. This indicates better homogeneity and better distribution of forsterite particles in the gelatin matrix due to the higher angular velocity. The number of coating layers has a slight effect on the corrosion resistance.