Two-Step Sintering and Spark Plasma Sintering of Al2O3, ZrO2 and SrTiO3 ceramics

The influence of Two Step Sintering and Spark Plasma Sintering processes on the microstructure of three kinds of oxide ceramics was studied. Al2O3 (with initial particle size of 240 nm), ZrO2 (60 nm, stabilized with 3 mol% Y2O3) and SrTiO3 (50 nm) powders were cold isostatically pressed and pressureless sintered with different heating regimes. It was found that the method of TSS does not bring about significant reduction of final grain size in Al2O3 and ZrO2 ceramics, but does reduce the grain size in perovskite SrTiO3 ceramics. Pressureless sintering of SrTiO3 leads only to 95%TD dense ceramics with the minimum grain size of 400 nm. In comparison, by SPS, with an applied uniaxial pressure of 200 MPa, SrTiO3 ceramic of 98%TD dense with grain size of 80 nm was prepared.