The phase composition of ZrB2 -SiC ultrahigh temperature ceramics (UTC)are analyzed by XRD,and
the quantitative analysis data were obtained from the Rietveld analyses. The results show that the phase compositions
of UTC are ZrB2,SiC,ZrO2,the quantitative analysis data from this work are close to the real ratio of the samples. The
Rietveld methord is reliable for the quantitative phase analysis of the ZrB2 -SiC ultrahigh temperature ceramics.