- Alumina, Silicon Carbide, Boron Carbide and Magnesium Aluminate Spinel were directly joined by a Spark Plasma Sintering (SPS) apparatus. The optimal parameters for joining (temperature, holding time and applied pressure) were experimentally found. The joined regions were investigated using scanning electron microscopy (SEM) ultrasonic and micro hardness testing. Alumina, Boron Carbide and Silicon Carbide parts were successfully joined at 1300, 1800 and 1900°C, respectively, for 30 min under argon atmosphere (10- 2 torr) and 40 MPa uniaxial pressure. Spinel parts were successfully joined at 1300°C for 60 min. Micro hardness of the interfacial regions were similar to those of the bonded specimens. The effect of a prolonged heat treatment on the microstructural evolution of the joined regions was investigated and the grain growth mechanism was discussed.