Spontaneous infiltrations of compound systems of Y2O3, Sm2O3, RE2O3, Al2O3 and AIN in SiC ceramics

Silicon carbide ceramics (SiC) are used in different applications in the engineering area due to the excellent properties, mainly in high temperatures. They are usually obtained by liquid-phase sintering enabling to form volatile products and, consequently, defects. The present work aims at studying the obtention of SiC ceramics by spontaneous infiltration using a eutectic composition of the Al2O3/Y2O3, AlN/Y2O3, Al2O3/Sm2O3, AlN/Sm2O3, Al2O3/RE2O3 and AlN/RE2O3 systems. RE2O3 is the concentrate of the rare-earth oxide obtained from Xenotime ore. Infiltration tests were carried out in argon atmosphere, graphite crucibles, in several temperatures near the melting point of each system, varying from 2.5 to 60 min. It was observed that Al2O3/Y2O3, Al2O3/Sm2O3, AlN/Sm2O3 and Al2O3/RE2O3 systems do not infiltrate appropriately and the AlN/Y2O3 and AlN/RE2O3 systems infiltrated spontaneously more than 20 mm; however, the first one presented a higher degree of infiltration, approximately 97%.