Pressureless sintered silicon nitride ceramics were joined using mixed Y2O3
, Al2O3, SiO2 and Si3N4 powers. Joining was carried out at 1450 and 1600 de
grees C for 30 min, under an applied pressure of 5 MPa. The result of EPMA
in the cross-section of the joined region indicated that some elements of a
dhesive (Y, Al) diffused into Si3N4 to form a diffusion layer at lower temp
erature (1450 degrees C), but elements of Y and Al were distributed uniform
ly all over the cross-section of the joined samples at higher temperature (
1600 degrees C). From the results of 3-point bending measurement, an averag
e strength of 400 MPa was obtained for the samples bonded at 1600 degrees C
, which was approximately 57% of that of unbonded ceramics. (C) 1999 Elsevi
er Science Ltd and Techna S.r.l. All rights reserved.