Characterization and corrosion behaviour of plasma sprayed Zn-Sn alloy coating on mild steel

• Published in: Surface & coatings technology 2018-10, Vol.352, p.654-661
• Main Authors: Oladijo, O.P., Mathabatha, M.H., Popoola, A.P.I., Ntsoane, T.P.
• Format: Article
• Language: English
• Subjects: Coating; Corrosion; Corrosion resistance; Corrosion resistant alloys; Corrosion tests; Diffraction; Direct current; Electrochemical corrosion; Electrode polarization; Low carbon steels; Mechanical properties; Microhardness; Mild steel; Optical properties; Phase transitions; Plasma spray; Porosity; Protective coatings; Residual stress; Scanning electron microscopy; Sodium chloride; Steel; Substrates; Sulfuric acid; Surface properties; X-ray diffraction; Zinc base alloys; Zinc coatings; Zn-Sn
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2017.04.029

Extensive effort to enhance the mechanical and electrochemical surface properties of mild steel has been reported by various engineers worldwide. This investigation presents a comparative test of corrosion behaviour, residual stresses and coating characterization for different Zn-Sn alloy composition on mild steel substrate, with aim of enhancing surface properties and extending the application of mild steel in industries. Coating of about 200μm was successfully deposited by plasma spray on mild steel substrate. The residual stresses were measured by X-ray diffraction sin2ψ technique using Cu-Kα radiation. Characterization and mechanical properties of the surface were investigated using Optical, Scanning electron microscopy, XRD and Emco Dura Scan tester to observe the microstructure, grain size, porosity, phase changes and hardness determination. The corrosion behaviour was examined in NaCl and H2SO4 solution. Direct current (DC) polarization tests were conducted and electrochemical corrosion behaviour of the surfaces was studied using scanning electron microscope (SEM/EDX). The results show an improvement as evidenced by the increased in corrosion resistance in NaCl and H2SO4 solutions, as well as increased in microhardness values on the coating. •Deposition of Zn-Sn alloys was successfully carried out on mild steel surface by plasma spray technique•Characterization and mechanical properties of the coating have been investigated•X-ray diffraction was used to measure the residual stress of the coating•The residual stress of the Zn-Sn alloy coating were all compressive and of relatively low valued•A substantial advancement in corrosion resistance was attained in the coated samples