Comparative Study on Quantitation of Phase Component and Phase Composition of HfB₂-SiC-HfC Ceramics

Phase component and phase composition of two pressureless-sintered HfB2-SiC-HfC ultra-high temperature ceramic samples were quantitatively analyzed. The results obtained by two different methods were compared. The phase component and phase composition for HfB2, SiC and HfC phases are in consistence, suggesting that the two methods respectively based on X-ray diffraction (XRD) and scanning electron microscope (SEM) are both applicable to the phase quantification for ceramic composites. Trace WB phase was also detected and further quantified by the backscattered electron (BSE) method. XRD-K value method was successfully extended to quantify the low-solution phase components. Quantitative results of stable W solute levels in HfB2 and HfC phases in
both samples, which were prepared with different milling media and WC contents, indicate that the liquid phase plays a key role in the reactive-densification process. The loss of W by the SiC milling makes Si3N4 to be more suitable milling medium.