Joining of AlN and graphite disks using interlayer tapes by spark plasma sintering

• Joining of AlN and graphite was achieved by SPS.
• The effect of interlayer tapes contained either AlN and graphite or AlN was investigated.
• Both tapes contained 5 mass%Y2O3 as sintering aid of AlN.
• The maximum tensile strength of joints was obtained with the AlN-graphite composite.
• AlN and graphite were joined physically with Al–Y–O phase during SPS.

AlN and graphite disks were successfully joined using a polymer plasticized ceramic tape as the interlayer by spark plasma sintering (SPS). The tape contains either composite powders of AlN and graphite or AlN powders without graphite. Both tapes contained 5 mass% Y2O3 as the sintering aid of AlN. The joining was carried out at 1700–1900 °C and 30 MPa for 5 min. No other reaction phase except for Al2Y4O9 was identified in the joints. The maximum tensile strength of the joints was obtained when the AlN–graphite composite interlayer tape was used. The joining mechanism is attributed not to the chemical bonding, but to the physical bonding of the Al2Y4O9 phase, which is solidified from the molten Al–Y–O squeezing into the porous graphite under pressure during SPS.