EFFECT OF OXIDE ADDITION ON THE SINTERING AND HIGH-TEMPERATURE STRENGTH OF SI3N4 CONTAINING Y2O3

The effect of oxide addition on the sintering behaviour and high-temperature strength of Si3N4 containing Y2O3 was studied at 0.1 to 30 MPa N2 at 1600 to 2000° C. The addition of oxide, i.e. MgO, Al2O3, La2O3, or Nd2O3, was found to lower the densification temperature and increase the densification rate. The addition of Al2O3 or MgO reduced the strength of sintered materials at >1350° C. The addition of La2O3 or Nd2O3, on the other hand, did not affect high-temperature strength which remained equivalent to that of the material containing only Y2O3. These results indicate that the glassy phases in these systems are as refractory as that in the Si3N4-Y2O3. © 1990 Chapman and Hall Ltd.