Improvement of mechanical strength of 8 mol % yttria-stabilized zirconia ceramics by spark-plasma sintering

Dense 8 mol % yttria-stabilized zirconia (8YSZ) ceramics consisting of submicrometer-sized grains were prepared using the spark-plasma sintering (SPS) method without any additives. The starting powder (ca. 0.1 mum) was densified to ca. 99% of the theoretical X-ray density with shorter sintering time (5-10 min) while preserving a grain size in submicrometer. The measured three-point bending strength was ca. 400 MPa at room temperature for samples sintered at 1300degrees C for 5-10 min, which was higher than the value of conventionally sintered ceramics, ca. 250 MPa, due mainly to the small-grained microstructures of the SPS ceramics. The electrical conductivity was 0.19 S cm(-1) at 1000degreesC in air, which is comparable to previously reported values (ca. 0.1 S cm(-1)) for well-sintered ceramics. Thus, the SPS method is an effective process to improve the mechanical strength of 8YSZ without degrading the electrical conductivity. (C) 2002 The Electrochemical Society.