Effect of Ni-Coated-Al2O3 Addition on Corrosion and Wear Resistance of Laser Cladded Fe-Based Composite Coatings

Abstract

In this paper, Fe-based composite coatings reinforced by Ni-coated-Al₂O₃ particles were prepared by laser cladding to investigate the influence of Ni-coated-Al₂O₃ addition on corrosion and wear resistance. Microstructure and microhardness of Fe-based composite coatings were characterized by using x-ray diffraction, scanning electron microscope and Vickers hardness tester. Corrosion behavior was evaluated using potentiodynamic polarization tests and electrochemical impedance spectroscopy experiments. Wear behavior was conducted by a dry reciprocating sliding wear tester. Results show that Fe-based composite coatings exhibit smooth columnar microstructure and grain refinement induced by the addition of Al₂O₃ ceramic particles. The microhardness of the Fe-based composite coating is much higher than that of the substrate and increases with the increase in Ni-coated-Al₂O₃ content. The corrosion current density of Fe-based composite coatings is 5.84 × 10^-4 A·cm^-2 for pure Fe-based coating, 2.37 × 10^-4 A·cm^-2 for 1 wt.% Ni-coated-Al₂O₃ coating, 2.09 × 10^-4 A·cm^-2 for 3 wt.% Ni-coated-Al₂O₃ coating and 10.70 × 10^-4 A·cm^-2 for 5 wt.% Ni-coated-Al₂O₃ coating, respectively. Corrosion resistance can be notably enhanced by appropriate addition of Ni-coated-Al₂O₃. Also, wear resistance of Fe-based composite coating has been significantly improved by the addition of Ni-coated-Al₂O₃. The Fe-based composite coating with 3 wt.% Ni-coated-Al₂O₃ displays the highest wear resistance. The wear mechanism of Fe-based composite coatings is a mixture of abrasive wear and adhesive wear as well as oxidation wear mechanisms. The proposed Fe-based composite coatings can be applied to improve the corrosion and wear resistance of components in contact with high-speed fluids, such as hydraulic turbine blades and ship propellers.