Enhanced Surface Hardness of Commercially Pure Titanium by Pack Carburization with Rubberwood Charcoal and Rubberwood Ash

In the present work, pack carburization with rubberwood charcoal and rubberwood ash at 925 °C for 6, 12, and 24 h was carried out to improve the surface hardness of commercially pure titanium (CP-Ti).  X-ray diffraction and energy dispersive spectrometer analyses revealed the formation of titanium carbide (TiC) and the existence of oxygen diffusion in the carburized surface. The surface hardness of most optimized conditions has remarkably increased by 481 % as compared to untreated CP-Ti (from 175 HV to 1016 HV) due to the TiC surface layer, while the hardened oxygen diffusion layer of about 300 μm in-depth, as clearly seen in the microhardness profiles is useful for increased load-bearing capacity. Consequently, pack carburization with rubberwood charcoal and rubberwood ash is a promising surface modification technique, which can significantly enhance the surface hardness and increase the load-bearing capacity of CP-Ti for biomedical and tribological applications. HIGHLIGHTS Rubberwood charcoal and ash are a new carbon source to fabricate the TiC layer on CP-Ti. Formation of the TiC layer remarkably enhances the surface hardness of CP-Ti by 481 %. The hardened oxygen diffusion layer is beneficial to load-bearing and anti-wear capacity. GRAPHICAL ABSTRACT