High performance aluminized Monel coatings with prolonged corrosion resistance in saline environment

Abstract

This study compares the corrosion resistance of as-sprayed and aluminized Monel 400 coatings annealed at 900 °C, and deposited on sand-blasted stainless steel. The coatings were immersed in 3.5 wt % NaCl solutions and analyzed using electrochemical impedance spectroscopy and cyclic Potentiodynamic polarization techniques for up to 100 days. Microstructural analysis showed decreased porosity as well as oxide and aluminide layer formation in annealed Monel 400 coatings. Formation of aluminides enhances the Vicker's hardness up to 4 times as compared to as-sprayed coatings. The results showed that the annealed coatings, particularly the aluminide coatings, exhibited higher corrosion resistance than the as-sprayed coatings. Additionally, the corrosion rate decreased exponentially, and the polarization resistance increased significantly as the immersion time increased. This study provides insights into cost-effective Ni-based coatings for corrosion resistance applications.