Effect of AlN additive on densification, microstructure and strength of liquid-phase sintered SiC ceramics by spark plasma sintering

Inhibition of grain growth in liquid-phase sintered SiC ceramics by AlN additive and spark plasma sintering

“…This tendency was identical to the result in the sintering of submicron-sized ␤-SiC powder with AlN and Y 2 O 3 additives by SPS. 25 The crystalline phase appearing in the samples was mainly 3C (␤-SiC). The peaks of 2H and 4H (␣-SiC) phases were detected in the sample without AlN additive.…”

“…The density of specimens prepared from submicron-sized ␤-SiC powder also increased with increasing content of AlN additive. 25 The density of the sample containing 100 mol% AlN additive decreased to 88%. These densities were higher than those of the SiC specimens prepared from nanosized ␤-SiC powder containing 4 mass% free carbon at sintering temperatures of 1800-2000 • C for 600 s by SPS.…”

“…This result was similar to SiC ceramics fabricated using submicron-sized ␤-SiC powder with AlN and Y 2 O 3 additives. 25 The grain size for the fully dense sample prepared using 90 mol% AlN additive was 150 nm. In the specimen prepared with Al 2 O 3 additive, on the other hand, the grain grew to the size of about 1 m, and the grain size was larger than those of the samples prepared with 30-90 mol% AlN additive.…”

“…The low-sinterable materials such as Al 2 O 3 , Si 3 N 4 , TiN, SiC, SiAlON and composites have been produced as fully dense materials by SPS technique. [16][17][18][19][20][21][22][23][24][25][26][27] In our previous study, 25 on SPS of submicron-sized ␤-SiC powder with AlN and Y 2 O 3 additives, the addition of AlN was found to result in a retardation of grain growth during SPS and an increase in mechanical strength for the SiC bodies. Also, when nanosized ␤-SiC powder containing about 4 mass% of free carbon was sintered with AlN and Y 2 O 3 additives by SPS at temperatures of 1800-2000 • C for 600 s, the full densification was not achieved, in which the relative density was 90-95% and the many residual pores were observed in the SiC bodies.…”

Nanostructured silicon carbide ceramics fabricated through liquid-phase sintering by spark plasma sintering

“…In contrast, with 5 and 10 vol % additives, 2H phase was identified. In the author's previous study, 8) 2H phase formed with increasing composition of AlN in 10 vol % AlNY 2 O 3 additive and 4H phase formed in the SiC body sintered with Al 2 O 3 additive. Since AlN has 2H structure, AlN is possible to form a solid solution with 2H-SiC.…”