Non-uniform sintering of yttria-stabilized zirconia powder compact

Abstract

Non-uniform sintering of yttria-stabilized zirconia powder compactSinteringb ehavior in both axial and radial directions has been studied for bothpure and doped 8mol.% yttria stabilized zirconia( 8YSZ) with differentc oncentrations of lithium nitrate. Detailed measurements were conducted at differentp ositions in radial and axial directions to study the spatial variation in sinteringo ft he powder compact. Doping with lithium nitrate was used to study the effect of varyingthe sinteringrate on the spatialvariation of sintering. It was shownthat variation in sinteringstrain in the axial direction is small, whereas alinear gradient is noticeable in the radial direction. The variation in radial strain peaksat relatively low strains (5 -10%)and reduces to aminimum at the end of sintering. Comparing average axial and radial strains showed that radial strainisconsistently higher than axial strain, implying that sintering is anisotropic especially during the intermediate stage. Density is determined in two ways: (1)Calculated based on measured volumetric strain, (2) calculated assuming sinteringisisotropic; the two quantities are compared. It is shownthat density divergence can rise to as large as 15 %and nearly vanishes at the end of sintering.