Conformal ZrC Interphase for ZrB2 Ceramics from a Solvent-Activated Metallopolymer

Implementing the advantages of preceramic polymers in modern ultra-high temperature ceramic (UHTC) manufacturing remains a significant challenge due to the limited preceramic polymer chemistry, which often is not fully amenable to ceramic processing conditions. Here, we present a solvent-activated, zirconocene dichloride-mediated ring-opening of poly(glycidyl methacrylate) that generates a zirconium-rich crosslinked network (X-mPGMA), allowing the metallopolymer to function both as a ZrC nanoparticle precursor and a colloidal processing gelcasting system. We utilize this metallopolymer gel chemistry to cast and consolidate near-net-shape ZrB2 green bodies. After carbothermal reduction and sintering, the crosslinked preceramic network yields a distinct ZrC phase that conformally coats the ZrB2 particles. Owing to the conformal ZrC interphase formed in situ, a finer ZrB2 microstructure was revealed, even under high-temperature sintering conditions. We further employed two gelcasting variants to near-net-shape and consolidate ZrB2 with and without added ZrC nanoparticles. Compared with the X-mPGMA-derived ZrB2 composites, these variants showed significant grain growth of ZrB2 after sintering, underscoring the effectiveness of in situ ZrC formation. This work highlights a powerful chemical processing strategy for effectively implementing multi-purpose, topologically distinct preceramic polymer-derived interphases in modern UHTC processing.