ZrB2–SiC–G Composite Prepared by Spark Plasma Sintering of In-Situ Synthesized ZrB2–SiC–C Composite Powders

To avoid introduction of milling media during ball-milling process and ensure uniform distribution of SiC and graphite in ZrB 2 matrix, ultrafine ZrB 2 –SiC–C composite powders were in-situ synthesized using inorganic–organic hybrid precursors of Zr(OPr) 4 , Si(OC 2 H 5 ) 4 , H 3 BO 3 , and excessive C 6 H 14 O 6 as source of zirconium, silicon, boron, and carbon, respectively. To inhabit grain growth, the ZrB 2 –SiC–C composite powders were densified by spark plasma sintering (SPS) at 1950°C for 10 min with the heating rate of 100°C/min. The precursor powders were investigated by thermogravimetric analysis–differential scanning calorimetry and Fourier transform infrared spectroscopy. The ceramic powders were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The lamellar substance was found and determined as graphite nanosheet by scanning electron microscopy, Raman spectrum, and X-ray diffraction. The SiC grains and graphite nanosheets distributed in ZrB 2 matrix uniformly and the grain sizes of ZrB 2 and SiC were about 5 μm and 2 μm, respectively. The carbon converted into graphite nanosheets under high temperature during the process of SPS. The presence of graphite nanosheets alters the load-displacement curves in the fracture process of ZrB 2 –SiC–G composite. A novel way was explored to prepare ZrB 2 –SiC–G composite by SPS of in-situ synthesized ZrB 2 –SiC–C composite powders.