Effect of titanium diboride addition on the corrosion behaviour of sintered titanium composites in acidic and sodium chloride environments

Four titanium composites with varying titanium diboride contents of approximately 2.5 wt%, 5 wt%, 7.5 wt%, and 10 wt% were developed using the powder metallurgy technique. The sintered samples’ microstructure and hardness were assessed with the scanning electron microscope and microhardness indenter. The electrochemical behavior was studied using open circuit potential and potentiodynamic polarization in sodium chloride, hydrochloric, and sulphuric acid solutions. The addition of titanium diboride (TiB₂) has an appreciable effect on the observed electrochemical behavior. The polarization plots of the sintered samples were distinct, with almost identical active-passive behaviors. The sintered composites showed an appreciable improvement in corrosion resistance compared with the sintered titanium (Ti) in sodium chloride and hydrochloric acid solutions. However, the resistance of the sintered composites to corrosion in the sulphuric acid solution decreased with increasing TiB₂ contents due to the aggressive attack of the ions. In the microstructural examinations, a higher dispersion of TiB₂ was observed for the sintered samples with increasing TiB₂ contents, and the hardness values range between 188 HV1 and 304 HV1.