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Abstract: Yb- and Y-doped α-SiAlON ceramics were effectively bonded by spark plasma sintering in less than 20min without using any interlayer materials at 1650–1700°C. The microstructures and mechanical properties of the joints were investigated by means of SEM, STEM, EDX, and three-point bending tests. The results showed that α-SiAlON joint formation was accompanied by fundamental rare earth diffusion. The intergranular liquids in the α-SiAlON ceramics at the bonding temperatures provided the diffusion paths for the species. α-SiAlON grain growth across the joining interfaces modified the joint microstructures to secure high bonding strength. [Copyright &y& Elsevier]

Si-B-C-N ceramic monoliths with LaB 6 additive were prepared by mechanical alloying followed by spark plasma sintering. The microstructures and mechanical properties were investigated compared to LaB 6 -free Si-B-C-N counterparts. After sintered at 1900 °C/50 MPa, the La/Si-B-C-N monoliths provide well-developed BN(C) flakes (≤100 nm in thickness) and improved fracture toughness, while the BN(C) ones show no lamellar microstructures in Si-B-C-N systems. The solid-solution of La in BN(C) grains promotes ordered arrangement of BN(C) along the (0002) plane causing in situ growth of BN(C) thus leading to an increase in toughness by 40% (from 5.6 to 7.8 MPa m −1/2 ). [ABSTRACT FROM AUTHOR]