Abstract
A novel approach for synthesizing nickel (II) oxide (NiO) nanoparticles was developed by chemically precipitating nickel (II) chloride (NiCl2) derived from dissolving pure solid nickel in concentrated hydrochloric acid. The synthesized nano-particles were then characterized and evaluated as a corrosion inhibitor for mild steel. Structural, morphological, and thermal properties were analyzed using XRD, FTIR, TEM, SEM-EDX, TGA/DTA, and DSC techniques. The nanoparticles exhibited a highly crystalline structure with an average crystallite size of 23.03 nm, which was consistent with TEM analysis showing individual particle sizes between 10.02 and 28.50 nm. Thermal analysis revealed a significant decomposition event at 519.4 °C, indicating high thermal stability. The corrosion inhibition potential was assessed on mild steel specimens coated with an epoxy resin containing 1 wt. % NiO nanoparticles and immersed in a 3.5 wt. % NaCl solution. The results demonstrated a substantial decrease in corrosion rate with the addition of NiO. The epoxy-1 wt% NiO nanocomposite coating provided the highest inhibition efficiency compared to the sample coated with only epoxy resin and the uncoated sample reaching 91.0 % and required a higher activation energy to initiate corrosion compared to both uncoated and neat epoxy-coated samples. This study confirms the successful synthesis of stable, crystalline NiO nanoparticles via a novel chemical precipitation method and establishes their superior performance as an active component in epoxy coatings for robust corrosion protection of mild steel.