Effect of Additives on the Reactive Sintering of Ti-B4C Composites Consolidated by Hot Pressing and Pressureless Sintering

Composites based on boron carbide (B4C) have drawn attention due to their outstanding physical and chemical properties. Herein, the effect of adding boron, titanium, and both titanium and boron, on the B4C-based material, is investigated. In addition, the additives' influence on the temperature of composite synthesis and the whole sintering process is evaluated. The Ti-B4C composites are prepared by two different methods: pressureless sintering and hot pressing. The presence of Ti, B, and C as dominant additives in the sintered composites is confirmed by X-ray diffraction and scanning electron microscopy (SEM). The SEM examination reveals that TiB2 particles formed during the composite process synthesis are distributed homogeneously in the B4C matrix. Mechanical properties, such as hardness, Young's modulus, and fracture toughness are tested, along with the composites' density and porosity. All the sintered samples, regardless of the incorporated additives, are characterized by high mechanical properties, reaching outstanding values in a few cases. The obtained results allow us to state that the usage of a boron and titanium mixture significantly improves the sintering process of composites due to the reactive sintering phenomenon occurring during the composites' preparation. The Ti-B4C composites are classified as ultrahigh-temperature ceramics materials.