Liquid Boriding of Cp-Ti and Ti6Al4V Alloy: Characterization of Boride Layers and Tribological Properties

Commercially pure titanium Cp-Ti and Ti6Al4V alloy were liquid bonded using a borate bath consisting of 70% borax and 30% SiC at 1000 degrees C for 3, 6, and 12 h. The borided materials were characterized by scanning electron microscopy to reveal the produced microstructures. Two kinds of titanium borides were identified by the X-ray diffraction analysis (TiB2 on the top of the surface followed by TiB whiskers penetrating into the substrate). The kinetics of formation of titanium borides was also investigated. The hardness of titanium borides was measured by means of the Vickers indenter. The generated Ti borides were characterized by high values of surface hardness. The wear resistance of bonded materials (at 1000 degrees C for 12 h) was analyzed by measuring the relative mass loss in comparison with that of the untreated materials. In addition, the wear mechanism was elucidated for both borided and untreated materials. As a result, liquid boriding was found efficient for improving the wear resistance of both materials.