Synthesis, Characterization, and Microstructure of ZrC/SiC Composite Ceramics via Liquid Precursor Conversion Method

The ceramic precursor for ZrC/SiC was prepared via solution-based processing using polyzirconoxane, polycarbosilane, and divinylbenzene. The precursor could be transformed into ZrC/SiC ceramic powders at relative low temperature (1500 degrees C). The cross-linking process of precursor was studied by FT-IR. The conversion from precursor into ceramic was investigated by TGA, XRD. The ceramic compositions and microstructures were identified by element analysis, Raman spectra, SEM, and corresponding EDS. The results indicated that the ceramic samples remained amorphous below 1000 degrees C and t-ZrO2 initially generated at 1200 degrees C. Further heating to 1400 degrees C led to the formation of ZrC and SiC with the phase transformation of ZrO2 and almost pure ZrC/SiC could be obtained upon heat-treatment at 1500 degrees C. During heat treatments, the ceramic sample changed from compact to porous due to carbothermal reduction. The ceramic powders with particle size of 100nm similar to 400nm consisted of high crystalline degree ZrC and SiC phases, and Zr, Si, C were well distributed at the different sites in ceramic powders. The free carbon content was lowered to 1.60 wt% in final ZrC/SiC composite ceramics.