云南11选5遗漏投注技巧 www.crmze.com To avoid introduction of milling media during ball-milling process and ensure uniform distribution of SiC and graphite in ZrB2 matrix, ultrafine ZrB2–SiC–C composite powders were in-situ synthesized using inorganic–organic hybrid precursors of Zr(OPr)4, Si(OC2H5)4, H3BO3, and excessive C6H14O6 as source of zirconium, silicon, boron, and carbon, respectively. To inhabit grain growth, the ZrB2–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 ZrB2 matrix uniformly and the grain sizes of ZrB2 and SiC were about 5 lm and 2 lm, 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 ZrB2–SiC–G composite. A novel way was explored to prepare ZrB2–SiC–G composite by SPS of in-situ synthesized ZrB2–SiC–C composite powders.