Quantitative Analysis for Phase Compositions of ZrB2-SiC-ZrC Ultra-High Temperature Ceramic Composites

Three methods were applied and compared to perform quantitative phase analysis of ZrB2-SiC-ZrC ultra- high temperature ceramic composites: the K value method by powder X-ray diffraction, two SEM methods to combine secondary electron and backscattered electron images, and electron backscatter diffraction and energy dispersive X-ray spectroscope (EDS) mapping. K value method could be applied conveniently and simply, while the two SEM methods could not only be performed quantitative phase analysis but also reveal phase distribution and relationships. Results from the three methods all show significant deviation of phase compositions from the composite designing of reactive sintering, while they are largely consistent with each other. The content of impurity ZrO2 phase is detected more than 5vol%, and in contrast, the content of secondary ZrC phase is found substantially below the theoretical 5vol% level and even below 1vol% as calculated by the more sensitive K value method. These quantitative phase analysis could provide technical supports to study the true composite microstructure and phase designing.