Study on corrosion and wear behaviors of laser cladding TiC-TiBx/TiNi-Ti2Ni intermetallic composite coating

Abstract

In order to improve the hardness and surface properties of TC4 titanium alloy, in-situ synthesis by laser cladding is used in this paper. A TiC-TiBx reinforced intermetallic composite coating was fabricated on Ti-6Al-4V titanium alloy by laser cladding with preplaced the high purity B4C, Ti and Ni powders. The microstructure, morphology and composition of the composite coating were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The Tafel polarization tests and dry sliding wear tests were employed to study the corrosion and wear behaviors of the composite coating. The results show that the coating has good metallurgical bond with the substrate, both crack and air hole are not found. The composition of the coating includes in-situ synthesis TiC-TiBx and TiNi-Ti2Ni dual phase intermetallic composite. The microhardness increases from 300 HV0.2 for the substrate reaching a peak as high as 930 HV0.2 for hard particles reinforced intermetallic composite coating. The wear resistance of the coating is improved significantly, due to combined action of hard ceramic reinforcements and ductile intermetallic matrix. While the untreated titanium alloy shows a passive behaviour, the composite coating reveals high electrochemical inertia and low corrosion currents. The strengthening mechanism of cladding is also studied.In order to improve the hardness and surface properties of TC4 titanium alloy, in-situ synthesis by laser cladding is used in this paper. A TiC-TiBx reinforced intermetallic composite coating was fabricated on Ti-6Al-4V titanium alloy by laser cladding with preplaced the high purity B4C, Ti and Ni powders. The microstructure, morphology and composition of the composite coating were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The Tafel polarization tests and dry sliding wear tests were employed to study the corrosion and wear behaviors of the composite coating. The results show that the coating has good metallurgical bond with the substrate, both crack and air hole are not found. The composition of the coating includes in-situ synthesis TiC-TiBx and TiNi-Ti2Ni dual phase intermetallic composite. The microhardness increases from 300 HV0.2 for the substrate reaching a peak as high as 930 HV0.2 for hard particles re...