In this study, the tribological behaviors of Mo2BC ceramics against four different counterpart materials were studied. It was established that the tribological properties of Mo2BC were sensitive to the counterpart material. For the Mo2BC/SiC and Mo2BC/Al2O3 tribo-pairs, a layer of tribofilm, mainly consisting of MoO3, was generated owing to the tribo-oxidation reaction. However, the tribofilm did not provide lubrication under ambient conditions. Tribo-oxidation and adhesion wear were the main wear mechanisms. For the Mo2BC/Si3N4 tribo-pair, only minor MoO3 tribo-oxides were generated, and the tribo-pair showed better tribological properties; the friction coefficient was as low as 0.42. The dominant wear mechanism was two-body abrasion. The Mo2BC/GCr15 steel tribo-pair showed a high friction coefficient, owing to the adhesion effect of Fe.

Single-phase polycrystalline Mo2BC ceramic bulks were synthesized successfully from molybdenum, boron, and graphite powders using the spark plasma sintering method. Herein, it was established that the synthesis temperature of the Mo2BC ceramic could be as low as 1300 degrees C. Transmission electron microscopy (TEM) characterization confirmed that the crystal structure of the Mo2BC ceramic was comparable to that of the MoAlB ceramic. The Vickers hardness of the Mo2BC ceramic was measured to be 18.1 GPa. Additionally, the compressive strength, flexural strength, and fracture toughness were determined to be 1.74 GPa, 457.72 MPa, and 3.26 MPa. m1/2, respectively. The Mo2BC bulk exhibited typical brittle features, in which intergranular and transgranular fractures were the main failure modes.