EFFECT OF TRANSITION RARE-EARTH-METAL OXIDE ADDITIVES ON DENSIFICATION DURING SINTERING OF SI3N4

It is argued that the sintering and densification of Si3N4 based ceram ics, using transition metal or rare earth metal oxide additives, can b e described as an electronic mechanism involving a transfer of electro ns into the Si3N4-SiO2 valence band: this is consistent with a recentl y proposed model of bonding at metal/ceramic interfaces. Transition me tal/rare earth metal oxides with a 'metallic' character tend to aid de nsification during sintering of Si3N4-beta sialon whereas insulator ty pe metal oxides are less effective densifiers. (C) 1993 The Institute of Materials.