Characterization of B4C and PMN-PT ceramics produced by flash sintering

In this study, densification of PMN-PT piezoelectric and B4C covalent ceramic materials are carried out by electric field assisted/flash sintering method. The composition selected for PMN-PT materials system is 0.67[Pb(Mg1/3Nb2/3)O3]−0.33(PbTiO3). During flash sintering experiment, proper electric field (PMN-PT: 200 V/mm, B4C: 50V/mm) applied on both sample with suitable current cut-off value (PMN-PT :0,1 amp, B4C:0,5 amp) according to materials electrical properties. Flash sintering is accomplished in less than 90 sec at ~700 °C for PMN-PT and 150 sec at ~489 °C for B4C. Relative density for sintered sample is measured approximately 94 % an above which is reasonable values comparing with literature. SEM microstructure illustration exhibits proper consolidation morphology which is agreement with the relative density measurement. There is no local melting observed on grain and grain boundaries which suggests hindering excessive joule heating. According to XRD analysis, the said materials systems shows consistency in rhombohedral crystal structure and preserve their chemical and physical composition during whole experimental cycle. By electric field assisted/flash sintering technique, the sintering temperature for PMN-PT is decreased from 1200 °C to 700 °C along with a decrement in sintering time from 2 hours to 90 seconds. Hence, this densification method gains importance to reduce toxic Pb (lead) emission aroused at high temperature processes for PMN-PT piezoelectric ceramic. Regarding B4C covalent ceramic, sintering temperature is decreased from 1800 °C to 489 °C in conjunction with a decrement in sintering time from 48 hours to 150 seconds. Thus, this technique allows us to huge energy and time savings by reducing sintering temperature and time for B4C covalent ceramic. Keywords: B4C, Covalent Ceramic, Electric Field, Flash Sintering, Piezoelectric Ceramic, PMN-PT.