The role of SiO2 impurities in the microstructure and properties of Y-TZP

A study has been carried out into the effects of SiO2 impurities at the 0-1 mass% level on the sintering characteristics, microstructure, phase compos ition, and mechanical properties of Y-TZP. The results show that SiO2 impro ves sintering at low temperatures, but gives rise to increasing grain bound ary phase formation and reduction in sintered density for higher sintering temperatures. X-ray diffraction studies indicated that SiO2 impurities at t hese levels did not significantly affect the stability of the tetragonal ph ase responsible for the transformation-toughening phenomena, although signi ficant effects on the mechanical properties of the material were observed. A model is proposed to account for these effects in terms of the microstruc tural changes associated with the presence of SiO2 and changes in sintering conditions. (C) 1999 Elsevier Science S.A. All rights reserved.