Effect of two-step heating on transparency of MgAl2O4 ceramics fabricated by pulsed electric current sintering process

Abstract

In this work, MgAl2O4 transparent ceramics was fabricated from combustion-synthesized nanopowders by pulsed electric current sintering (PECS) combined with two-step sintering. Ceramic powder was densitified using two-step heating, namely the first-step temperature was 1100 oC with holding time of 60 min and the second-step temperatures in range from 1300 oC to 1450 oC with 20 min duration. The results showed that the transparent ceramic samples sintered at 1100 oC/60 min – 1400 oC/20 min had grain size of 177 ± 8 nm, relative density about 99 %, transmittance up to 80 %, and Vickers hardness of 18 GPa. These values were higher than that of samples obtained by one-step sintering at 1400 oC.