Microstructure And Properties Of Laser-cladding γ-Ni/Cr₁₃ Ni₅Si₂ Coatings

In this paper, the coatingsγ-Ni/Cr₁₃Ni₅Si₂ were fabricated by laser-clad process. The microstructures of the coatings were characterized by X-ray diffraction (XRD), energy dispersive spectrometry (EDS), scanning electron microscopy (SEM) and optical microscopy (OM). Hardness (HV), wear resistance as well as corrosion resistance were evaluated by vickers hardness, room-temperature dry sliding wear test and electrochemical corrosion test.The results showed that, the laser-cladded coatings consist of Cr₁₃Ni₅Si₂ dendritic phase andγ-Ni interdendritic compounds, in which the volume fraction ofγ-Ni increases with the increasing of Ni content as well as the decreasing of Cr and Si element content, and size of the dendritic decreases by faster scanning velocity. The microhardness of coatings emerge in gradient distribution along the depth direction away from coatings surface. And average hardness of coatings decrease with the increasing Ni content, and increase by faster laser scanning velocity. The coatings have more excellent wear resistance than AISI 304 stainless steel under room temperature dry sliding wear test. The wear rate of theγ-Ni/Cr₁₃Ni₅Si₂ coating first increases and then decreases with the increasing ofγ-Ni content; the coating has the most excellent wearability whenγ-Ni volume content accounts for about 40% of the total volume coating.Comparing wear resistance ounder different load condition, we can discovery that: the wear rate increases with the increasing test load; and the wear loss of the coating remains nearly unchanged with long test time. The laser-cladded coatings shows abnormal load-wear characteristics as well as low time sensitive characteristics.On the coatings wear mechanism analysis found that: The laser-cladded coatings with excellent wear resistance mainly due to the good combination of the hardness of Cr₁₃Ni₅Si₂ phase and the toughness ofγ-Ni phase.The results of electrochemical corrosion test indicate thatγ-Ni/Cr₁₃Ni₅Si₂ coatings have more excellent corrosion resistance than stainless steel in 3.5%NaCl solution, 1moL/LHCl solution as well as 1moL/LNaOH solution. And the corrosion resistance decrsese with the increasing of Ni content as well as the decreasing of Cr and Si element content in all test solutions.