Synthesis and characterization of zirconium diboride ceramic precursor

In the present study, ZrB2 precursor which met the requirements of polymer infiltration-pyrolysis process, was synthesized and characterized. ZrB2 precursor was synthesized with bis(cyclopentadienyl)zirconium dihydride (Cp2ZrH2), borane-dimethyl sulfide complex (BH3·S(CH3)2), and vinyltrimethylsilane ((CH3)3Si(CHCH2), VTMS). The molecular structure of the precursor, pyrolysis behavior, and the composition of the derived ceramics were investigated. The results showed that, the as-synthesized precursor was an oligomer based on Zr–H–B polycentric bridge bonds. The precursor was stable in an inert atmosphere. The ceramic yield of the precursor at 1200 °C was around 65.5% under N2 atmosphere. The derived ceramics obtained under 1200 °C were composed of h-ZrB2, m-ZrO2 and t-ZrO2. When the temperature was up to 1400 °C, peaks of ZrC emerged due to carbothermic reduction. m-ZrO2 and t-ZrO2 disappeared with the pyrolysis temperature above 1600 °C. The derived ceramics pyrolyzed at 1800 °C were composed of h-ZrB2 and ZrC, and the former was the predominant phase.