EXAMINATION OF HIGH TEMPERATURE MECHANICAL PROPERTIES OF CERAMICS USING SPARK PLASMA SINTERING (SPS) APPARATUS

The available data on mechanical properties of ceramics at high temperatures (tensile and compressive strength as well as creep) are limited mostly due to experimental difficulties of specimen preparation and testing. We suggest to use SPS apparatus, which allows to record with high accuracy deformation of specimens under controlled temperature, pressure and atmosphere. In the present work both stress-strain (for magnesium aluminate spinel, MAS) and creep tests (for alumina) were conducted in the 1000-1300°C temperature range under compression (up to 300MPa). The fully dense samples were fabricated by SPS from nano-metric powders without any additives. Typical stress-strain curve under compression was obtained for MAS and indicated that its yield stress at 1200°C is relatively low (of about 50MPa). This value allowed us to explain the consolidation behavior of MAS powder during SPS under high pressure. The comparison of the results on high temperature creep of alumina obtained by SPS apparatus with previously reported data confirms that SPS apparatus is a promising tool for the investigation of high temperature mechanical properties of ceramics as well as of metals.

Keywords: Alumina, Spinel, SPS, Creep, Yield stress.