Effect of laser remelting on amorphous formation and electrochemical corrosion of laser thermal sprayed Al–Ti–Ni coating

A laser thermal sprayed Al–Ti–Ni coating was fabricated on S355 structural steel with Al wire–packed Ti and Ni powders, which was processed by laser remelting (LR). The surface and cross–section morphologies, elemental chemicals, crystallization behavior, and phases with their chemical bonding states of obtained coatings were investigated using a scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), different scanning calorimetry (DSC), x–ray diffractometer (XRD), and x–ray photoelectron spectroscopy (XPS), respectively. The effects of LR times on the electrochemical corrosion properties of Al–Ti–Ni coatings were also assessed using a electrochemical workstation. The results show that LR appreciably reduces the surface porosity and improves elemental chemical homogeneity on the Al–Ti–Ni coating surface. The phases after multiple LR remain unchanged in the incomplete crystallized coatings, which are mainly composed of intermetallic compounds of Al 3 Ni, AlTi, AlFe and AlFe 3 . The Al–Ti–Ni amorphous coating after LR three times exhibits the lowest corrosion current of 7.068 × 10 –6 A · cm –2 and the largest polarization resistance of 4070 Ω cm 2 in 3.5% NaCl solution, its electrochemical corrosion resistance is the best among three kinds of LR times.