A superplastic beta -SiAlON was used as an interlayer to diffusionally bond
a hot-pressed silicon nitride to itself, The bonding was conducted in a gr
aphite furnace under a constant uniaxial load of 5 MPa at temperatures vary
ing from 1500 degrees to 1650 degreesC for 2 h, followed by annealing at te
mperatures in the range of 1600 degrees to 1750 degreesC for 2 h, The bonds
were evaluated using the four-point-bend method at both room temperature a
nd high temperatures. The results indicate that strong, void-free joints ca
n be produced with the superplastic beta -SiAlON interlayer, with bond stre
ngths ranging from 438 to 682 MPa, and that the Si3N4 joints are heat resis
tant, being able to retain their strength up to 1000 degreesC (635 MPa), an
d therefore have potential for high-temperature applications.