• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.11
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• pp.1108-1114
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• 2007

The low kinds of $Al_2O_3$ composite ceramics were prepared using a mixture of 85 wt.% $Al_2O_3$ (mean size $0.5\;{\mu}m$), 15 wt.% SiC Powder with $Y_2O_3$, as an additive powder (0, 1, 3 and 5 wt.%). The crack-healing strengths were studied as functions of crack-healing temperature and amount of $Y_2O_3$. The in-situ crack-healing behavior was observed at 1,573 K for 1 h in the air. The heat treated specimen with 3 wt.% of $Y_2O_3$ showed better crack-healing ability than specimen with 1 or 5 wt.% of $Y_2O_3$. In case of specimen with 3 wt.% of $Y_2O_3$, the bending strength of the crack-healed specimen at 1,473 K was recovered to the bending strength of smooth specimen treated at 1573 K. The heat-resistance limit temperature of $Al_2O_3$ composite ceramics was 1,073 K, 1,373 K, 873 K for the specimen with 1, 3, 5 wt.% of $Y_2O_3$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.483-487
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• 2014

In this study, joining methods with SiC powder as the joining adhesives were studied in order to avoid the residual stresses coming from CTE (Coefficient of Thermal Expansion) mismatch between substrate and joining layer. The shear strength and microstructure of joined material between SiC substrates are investigated. The commercial Hexoloy-SA (Saint-Gobain Ceramics, USA) used in this work as substrate material. The fine ${\beta}$-SiC nano-powder which the average particle size is below 30 nm, $Al_2O_3$, $Y_2O_3$, and $SiO_2$ were used as joining adhesives. The specimens were joined with 20MPa and $1400-1900^{\circ}C$ by hot pressing in argon atmosphere. The shear test was performed to investigate the bonding strength. The cross-section of the joint was characterized by using an optical microscope and scanning electron microscopy (SEM).