Processing and Properties of TiB2 with MoSi2 Sinter‐additive: A First Report

Abstract

The densification of non‐oxide ceramics like titanium boride (TiB2) 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 TiB2 materials densified using a MoSi2 sinter‐additive. The densification experiments were carried out using a hot‐pressing and pressureless sintering route. The binderless densification of monolithic TiB2 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% MoSi2 enables us to achieve 97%–99%ρth in the composites at 1700°C under similar hot‐pressing conditions. The densification mechanism is dominated by liquid‐phase sintering in the presence of TiSi2. In the pressureless sintering route, a maximum of 90%ρth is achieved after sintering at 1900°C for 2 h in an (Ar+H2) atmosphere. The hot‐pressed TiB2–10 wt% MoSi2 composites exhibit high Vickers hardness (∼26–27 GPa) and modest indentation toughness (∼4–5 MPa·m1/2).