EFFECTS OF NANO-SIZED SILICON-CARBIDE PARTICULATE ON MICROSTRUCTURE AND IONIC-CONDUCTIVITY FOR 8-MOL-PERCENT YTTRIA-STABILIZED ZIRCONIA BASED NANOCOMPOSITES

Strong 8 mol% Y2O3 stabilized zirconia (8YSZ)/silicon carbide (SiC) na nocomposites were fabricated by using hot-pressing technique, and effe cts of dispersed nano-sized SiC particles on microstructure and ionic conductivity of 8YSZ were investigated. Fine SiC particulate inhibited densification and normal/abnormal grain growth of 8YSZ matrix grain d ue to the decrease of grain boundary diffusivity and mobility. The nan ocomposites had fine and homogeneous microstructure, and this phenomen on became more obvious with increasing SiC: content. The total conduct ivity decreased with increasing SiC content due to the decrease in gra in boundary conductivity, which should be related to the increase in g rain boundary length and the decrease of effective volume of ionic con ductor by SiC particles at grain boundaries. For lattice conductivity, the 5 vol% SiC particulate dispersed composite had similar lattice co nductivity to the 8YSZ monolith. However, the 20 vol% SIC particulate dispersed composite was found to show higher conductivity than the mon olith, which should be attributed to the extension of lattice spacing by the residual stress depends on the thermal expansion mismatch betwe en 8YSZ matrix and SiC particles. (C) Published by Elsevier Science B. V. All rights reserved.