Thermodynamical evaluation, microstructural characterization and mechanical properties of B4C–TiB2 nanocomposite produced by in-situ reaction of Nano-TiO2

Abstract

This work discusses the pressureless sintering of a boron carbide-titanium diboride (B4C– TiB2) nanocomposite via in-situ reaction of the boron carbide/titanium dioxide/carbon system. Attempting to sinter pure boron carbide leads to poor mechanical properties. In this work, the effect of adding TiO2 to B4C on mechanical properties of the boron carbide was investigated. Thermodynamic simulations were performed with HSC chemistry software to determine the phases which were most likely to form during the sintering process. The reaction thermodynamics suggested that during the sintering process, formation of TiB2 occurs preferentially over formation of TiC. For examination of the microstructural evolution of the samples, Scanning Electron Microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were utilized. The density, porosity, Young's modulus, microhardness and fracture toughness of the specimens were compared. Optimum properties were achieved by adding 10 wt% TiO2. In the sample possessing 10 wt% TiO2, the relative density, Young's modulus, hardness and fracture toughness were 94.26%, 428 GPa, 23.04 GPa and 5.19 MPa m0.5, respectively, and the porosity was decreased to 5.73%. Furthermore, phase analysis via XRD confirmed that the final product was free of unreacted TiO2 or carbon.