Dilatometry data for high-field flash sintering of oxide ceramics
Description
Provided are raw datasets of the dilatometry taken during the high-field flash sintering tests on non-sintered and (approximately) fully pre-sintered samples. Curves are provided in GERMAN .csv format (Semicolon-separated, comma as decimal separator). The dilatometery data was used to determine the onset temperatures of the flash event based on the thermal expansion/fracturing behavior. ATTENTION: The dilatometry curves of this dataset must not be interpreted as shrinkage due to flash sintering. In nearly all cases it represents the fracturing of the samples due to the rapid runaway at the high fields. The curves were used to verify that a proper thermal runaway, signified by a small thermal expansion right before the flash event, takes place for each measurement. This dataset belongs to a manuscript currently under review in Acta Materialia. Title of the manuscript is "Flash sintering in oxides: the Debye temperature is not the limit" by Daniil Lewin and Doru C. Lupascu. Corresponding author is Daniil Lewin and can be contacted at daniil.lewin@uni-due.de
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Experimental details (Section copied from original manuscript) Conventional flash sintering experiments were conducted on five different oxides for applied voltages of up to 1500 V using an EA-PSB 11500 power source inside a Netzsch DIL 402 Expedis Select dilatometer. The electric field was applied coaxially to the dilatometry axis through plate platinum electrodes (6.5 mm diameter, nominally 0.5 mm thickness). The set current limit of the experiment was 500 mA for barium titanate (BaTiO3), strontium titanate (SrTiO3) and cobalt ferrite (CoFe2O4), and 4000 mA, the maximum current value our setup can safely handle, for copper oxide (CuO) and titanium trioxide (Ti2O3). The difference in current limits is necessary due to the high conductivity of the latter two materials. The furnace ramping rate was 10 °C/min in all cases, except for experiments done at room temperature. Both pre-sintered ceramics and non-sintered green bodies were used for the flash sintering experiments. The reasoning for the specific material choices and the preprocessing parameters are part of the discussion. The samples were prepared as follows: Cylindrical green bodies were prepared by uniaxial pressure of ~200 MPa. Cylindrical barium titanate (Sigma Aldrich, >99 %, ~700 nm particle size) and strontium titanate (Thermo Fisher Scientific, >99 %, ~1 μm particle size) green bodies were pre-sintered for four hours at 1350 °C and 1400 °C, respectively, to achieve a density of >98% with geometries of roughly 5 mm diameter and 4.5 mm height. Flash sintering experiments were also conducted with respective non-sintered cylindrical green bodies of a relative density of ≈ 50 % for comparison (5.5 mm height, 6.5 mm diameter). Cylindrical cobalt ferrite (CoFe2O4, PI-KEM Ltd., >98 %, ~40 nm particle size) samples were also sintered at 1200 °C for 4 hours to approximately full density. These samples are noticeably smaller with a height of just 2.2 mm and a diameter of 4.8 mm. Non-sintered cobalt ferrite green bodies were not used for flash sintering experiments. Copper oxide (CuO, Thermo Fisher Scientific, >99 %, ~325 mesh size) and titanium trioxide (Ti2O3, >99.8 %, ~325 mesh size) were exclusively investigated as cylindrical green bodies of ≈ 50 % density (4 mm height, 6.5 mm diameter).
Institutions
- Universitat Duisburg-Essen Institut fur Materialwissenschaft
- Universitat Duisburg-Essen Center for Nanointegration Duisburg-Essen
- Universitat Duisburg-Essen