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Detailed Program
Paper Number : EF-I02
Time Frame : 15:25~15:50
Presentation Date : Friday, 28, November
Session Name : Electric Field Assisted Sintering
Session Chair 1# : Young-Hwan Han
Session Chair 2# : Tetsuo Uchikoshi
Influence of Carbon Nanotubes on Phase Transformation (t - m) of Spark Plasma Sintered ZrO2
Young-Hwan Han
Yeungnam University
A technique of Spark Plasma Sintering (SPS) uses the idea of pressure driven powder consolidation under pulsed direct electric current which is passed through a sample compressed in a graphite die set. In general, the SPS process results in a finer grain size. The reported phase transformation fraction on fractured surface still encountered contradiction and the phase transformation behavior of ZrO2/CNT composite in indentation range has never been systematically studied. These differences may be resulted from the dispersion state of CNTs, sintering condition and therefore the microstructure and residual stress state of the composites. The densification behavior during SPS, microstructure and mechanical property were examined. Commercial 3YSZ/CNT composite powder (Applied Carbon Nanotechnology Co., LTD, Korea) with a CNT content of 0, 1, 3, 5 and 10 vol.% were used as the starting powders. The ZrO2/CNT composite powders were produced by a high energy ball milling process. The composite powders underwent SPS (FCT Gmbh, Germany) in a vacuum at 1300oC at a heating rate of 100oC/min and holding time of 3 min. The pressure load was initially 30 MPa and was increased linearly to 60 MPa when the temperature reached 1300oC. The addition of CNTs could also lead to refined grain size, improved fracture toughness while reduced Vickers hardness and nanoindentation. An initially decreasing and then increasing tendency for the tetragonal to monoclinic phase transformation were observed at 5% CNT addition in the indentation of composites by the Raman technique, also characterized by XRD, SEM, TEM, and AFM.


Figure1 (a) X-ray diffraction patterns of the ZrO2/MWCNT composites. (b) Apparent particle size measured From SEM and the crystal size estimated from XRD patterns.
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