Synthesis, microstructure and mechanical properties of lamellar YB2C2 – based ultra-high temperature ceramic composites

A significant improvement of the mechanical performance was observed following introduction rare earth oxides in ZrB2-based ultra-high temperature ceramic matrix composites (UHTCMCs), resulting formation ternary boro-carbides general formula REB2C2, belonging to a new class layered compounds akin MAX phases. These phases possess high melting points and could be responsible for toughening UHTCMCs, but their formation, properties role were never fully investigated. In this study we focused on potential routes synthesis YB2C2 at temperatures typical UHTC sintering, starting from Y2O3, carbon four different boron sources (B, B2O3, BN, B4C) microstructure analysed by SEM, XRD TEM. The mixture with B4C led highest selectivity towards selected fabricate long fibre reinforced composite, which mechanically tested displaying flexural strength 380 MPa. Finally, chemical stability air these materials assessed.