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

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 (<1750 degrees C) and with greater MoSi2 aid content (>15 vol.%) than ever before. It was found that just 20 vol.% MoSi2 aid enables the full densification of B4C at 1700 degrees C, thereby avoiding the deleterious transformation beta-MoB2 ->alpha-MoB2, having consumed the entire MoSi2 to form MoB2 and SiC. This maximizes the hardness (similar to 33 GPa) of these novel triplex-particulate B4C-SiC-MoB2 composites without penalizing their toughness (similar to 4.1 MPa.m(0.5)). 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 similar to 10(-8) mm(3)/(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.

Automated summary

Through transient liquid-phase-assisted spark-plasma sintering at lower temperature and higher MoSi2 content, superhard B4C-SiC-MoB2 triplex-particulate composites with a hardness of around 33 GPa were successfully fabricated, demonstrating excellent wear resistance properties.