2192 Journal of the American Ceramic Society--Liversage et al Vol. 90. No. 7 Hot pressing axis Hot pressing axis ewing plane. TiC Sic x uctural features found on face. and edge-sections of four selected pric compositions. (a). (c),(e)and(g)show set of s taken of the face sections of STO00, ST020, ST066, and ST100, respectively, and (b)(d)(f)and (h) depict the edge sections for the corresponding comparison of the intensities of peaks that are uniquely attrib- assigned to polytypes of Sic are likely associated with the pres- utable to different polytypes, it is proposed that the most abu ence of Y-AHO oxide phases dant polytype in the present Sic system is that of the 6H The essential elements of the monolithic TiC diffraction p structure, with there being only minor additional quantities of tern, shown in Fig 8, are consistent with the diffraction peaks of 15R and 4H. This is in line with the more commonly encoun- the khamrabaevite structure In addition to the diffraction peaks ered polymorphic compositions found for liq associated with the khamrabaevite structure are peaks which SiC. Minor peaks in Fig. 7 which could not be conclusively were found to correspond to a possible two different oxidecomparison of the intensities of peaks that are uniquely attrib￾utable to different polytypes, it is proposed that the most abun￾dant polytype in the present SiC system is that of the 6H structure, with there being only minor additional quantities of 15R and 4H. This is in line with the more commonly encoun￾tered polymorphic compositions found for liquid-phase-sintered SiC.20,25 Minor peaks in Fig. 7 which could not be conclusively assigned to polytypes of SiC are likely associated with the pres￾ence of Y–Al–O oxide phases. The essential elements of the monolithic TiC diffraction pat￾tern, shown in Fig. 8, are consistent with the diffraction peaks of the khamrabaevite structure. In addition to the diffraction peaks associated with the khamrabaevite structure are peaks which were found to correspond to a possible two different oxide Fig. 3. A comparison of general microstructural features found on face- and edge-sections of four selected jTiC compositions. (a), (c), (e) and (g) show images taken of the face sections of ST000, ST020, ST066, and ST100, respectively, and (b) (d) (f ) and (h) depict the edge sections for the corresponding set of samples. 2192 Journal of the American Ceramic Society—Liversage et al. Vol. 90, No. 7