TEM analysis of nanocrystalline SiC ceramics sintered by SPS using Al2O3–TiO2 additive

• SiC ceramics was fully densified using Al2O3 and TiO2 additives by SPS.
• TiC and mullite phases were formed in SiC ceramics by the addition of Al2O3 and TiO2.
• Mullite (0 0 1) plane orientated in parallel to the SPS compressive plane.
• Ti atoms in addition to Al and O atoms segregated at grain boundaries in AT-SiC.

Nanocrystalline SiC ceramics was fabricated by spark plasma sintering (SPS) using Al2O3 and TiO2 additives with the composition of 5, 10 and 20 mass% (Al2O3–TiO2). XRD analysis revealed formation of TiC phase. And also mullite phase with preferred orientation was detected in SiC with 20 mass% addition. From TEM observation and EDS analysis, TiC, aluminosilicate glass and mullite crystal phases were identified. Segregation of titanium atoms in addition to aluminum and oxygen atoms was observed at intergranular glassy phase with the thickness of 1–2 nm. The electrical conductivity was the same level as the Al2O3 single addition to SiC ceramics.