Ultra-low wear B4C-SiC-MoB2 composites fabricated at lower temperature from B4C with MoSi2 additives

Abstract Seeking to fabricate B4C composites that are even more superhard (>30 GPa) at lower cost, B4C was transient liquid-phase assisted spark-plasma-sintered, somewhat counterintuitively, at lower temperature ( 15 vol.%) than ever before. It was found that just 20 vol.% MoSi2 aid enables the full densification of B4C at 1700 °C, thereby avoiding the deleterious transformation β-MoB2→α-MoB2, having consumed the entire MoSi2 to form MoB2 and SiC. This maximizes the hardness (∼33 GPa) of these novel triplex-particulate B4C-SiC-MoB2 composites without penalizing their toughness (∼4.1 MPa⋅m0.5). Also importantly, the dry sliding-wear of these novel composites was investigated for the first time, showing that they undergo only mild wear (specific wear rate of ∼10−8 mm³/(N⋅m)) by plasticity-dominated two-body abrasion. Moreover, it was demonstrated that they are much more wear resistant than porous B4C monolithics fabricated under both the same and more demanding conditions, and at least as equally wear resistant as fully-dense B4C monolithics and composites fabricated under more demanding conditions.