Comparison of Creep Behavior in Alumina Based Ceramics Densified by Spark Plasma Sintering and Hot Pressing

Spark plasma sintering (SPS) method, as plasma activated sintering, is a method applicable for rapid sintering of metals and ceramics. Owing to the advantage of rapid heating, the alumina ceramics obtained by SPS have a grain size and density comparable to those of hot pressed ones. The increase of densification rate may be related to some difference in ion transport characteristics. This study describes creep behavior and deformation mechanisms of alumina based materials densified by SPS, and somewhat comparison is made with hot pressing (HP) at high temperature. Pure alumina was densified by SPS at 65 MPa (1200 ºC) and 45 MPa (1400 ºC) by HP. The grain size of the alumina HPed was twice more than the grain size of the sample SPSed. Compressive creep tests in air were performed at different true stresses up to100 MPa and different temperatures (1200 ºC-1400 ºC). The grain growth was found to be more active during creep of SPS alumina than the creep of HP alumina. Generally, the fineness of SPS materials microstructure speeded up all processes related to diffusion. The ratio of dynamic to static grain growth in SPSed samples was twice more than HPed samples during creep test.