Consolidation of Ultrafine Alumina Powders with SPS Method

Current Isolation in Spark Plasma Sintering of Conductive and Nonconductive Ceramics

“…Shrinkage indicates the onset of the second stage of sintering where the point contacts would be replaced with large contact areas between the powders. Makino et al 11 measured the electric current that passed through the Al 2 O 3 compact during SPS processing and reported that it reached a maximum of only 100 mA at 1000°C. In a separate study, Tomino et al 15 determined that temperature distributions in the graphite mold and the sample indicated that the electric current did not flow through the sample.…”

“…The objective of this paper is to highlight observations of Al 2 O 3 in the SPS using direct (current passes through the sample) and indirect heating (current passes through the die). Al 2 O 3 is a suitable test material as there is a plethora of work describing SPS processing of Al 2 O 3 with which to compare our findings 1–4,6,8,11–13 …”

“…Al 2 O 3 is a suitable test material as there is a plethora of work describing SPS processing of Al 2 O 3 with which to compare our findings. [1][2][3][4]6,8,[11][12][13]…”

Observation and Control of Pore Formation in SPS-Synthesized Alumina

“…Further, it has indicated that the bending strength increases with the increase of the sintering temperature up to 1300 °C and then shows the remarkable decrease attributed to the formation of residual pores in the higher temperature than 1300 °C. On the other hand, highly dense aluminas (99.18 % TD) have been synthesized at 1150 °C by using SPS method under the conditions of 100 MPa and 50 °C/min 7) . Though many successful syntheses of highly dense aluminas by SPS have been reported 8) , the decrease of density, though slight, with increasing sintering temperature has not indicated until now, except for our previous work 6) .…”

“…In our previous paper 7) , we have tried to synthesize highly densified transparent aluminas by SPS method at a high heating rate of 100 °C/min and indicated that highly densified aluminas can be synthesized at 1150 °C under 100 MPa, with suppressing the grain growth down to about 300 nm in size. Thus, the nano- It is shown in Fig.…”