Processing and Properties of TiB 2 with MoSi 2 Sinter‐additive: A First Report

The densification of non‐oxide ceramics like titanium boride (TiB 2 ) has always been a major challenge. The use of metallic binders to obtain a high density in liquid phase‐sintered borides is investigated and reported. However, a non‐metallic sintering additive needs to be used to obtain dense borides for high‐temperature applications. This contribution, for the first time, reports the sintering, microstructure, and properties of TiB 2 materials densified using a MoSi 2 sinter‐additive. The densification experiments were carried out using a hot‐pressing and pressureless sintering route. The binderless densification of monolithic TiB 2 to 98% theoretical density with 2–5 μm grain size was achieved by hot pressing at 1800°C for 1 h in vacuum. The addition of 10–20 wt% MoSi 2 enables us to achieve 97%–99%ρ th in the composites at 1700°C under similar hot‐pressing conditions. The densification mechanism is dominated by liquid‐phase sintering in the presence of TiSi 2 . In the pressureless sintering route, a maximum of 90%ρ th is achieved after sintering at 1900°C for 2 h in an (Ar+H 2 ) atmosphere. The hot‐pressed TiB 2 –10 wt% MoSi 2 composites exhibit high Vickers hardness (∼26–27 GPa) and modest indentation toughness (∼4–5 MPa·m 1/2 ).