Investigation of Tin oxide using the electroless deposition technique as a composite coating for mild steel

Abstract

Corrosion control is a very serious problem in industries employing mild steel, which is widely used because of its low cost, versatility, and ease of processing. However, the susceptibility of mild steel to rapid corrosion and degradation of mechanical properties creates serious problems in many applications. This work investigates the electroless deposition of Ni-Sn-P coatings on mild steel for the improvement of its corrosion resistance. The coatings were deposited for 30 min in the aqueous bath at 45°C, pH 5, with a stirring rate of 150 rpm, with variable concentrations of SnO: 0, 2, 4, 6, and 8 g/L. The corrosion resistance tests of coated and uncoated mild steel were done by a potentiodynamic polarization in a 3.65% NaCl solution according to the ASTM G102. Microstructural characterization was performed by SEM/EDS and XRD. The uncoated mild steel exhibited a corrosion rate of 0.00046873 mm/year with a corrosion current density of 4.0338E-8 A/cm². In contrast, for Ni-Sn-P coatings, a tremendous improvement in corrosion resistance was manifested in the corrosion rate within the range from 0.00043612 to 0.00034325 mm/year, with corrosion current density values in the range from 4.0114E-8 to 1.2328E-7 A/cm². The improvement in corrosion resistance of mild steel is very high by Ni-Sn-P coatings; hence, the coating may serve as an alternative to many conventional corrosion-resistant coatings for industrial application in an aggressive environment.