Thermal plasma assisted rapid sintering of MgO-doped Al–Zr oxide composites

MgO-doped Al–Zr oxide composites of Zr0.95Al1.05MgxO with x = 0, 0.01, …, 0.05, 0.75, 1 were sintered to high density by both dc thermal plasma assisted rapid sintering as well as conventional sintering. It was observed that the above mentioned MgO-doped Al–Zr oxide composites were sintered to high density end products by the thermal plasma heating technique within a short sintering time (a few minutes) as compared to a conventional long range resistive heating schedule (a few tens of hours). Moreover, the densities of plasma sintered samples were found to be more than that of conventional sintered samples. It was also noticed that there exists a critical limiting point of MgO doping concentration (x = 0.05 in Zr0.95Al1.05MgxO) for maximum physical densification in both conventional as well as plasma sintered samples. Sintered specimens were analyzed by XPS, XRD and EPMA studies. XRD, XPS and EPMA studies revealed the presence of a high density phase, Mg2Zr5O12 prominently in x = 0.05 sintered sample which resulted in maximum densification of the sample. Thus, MgO doping in small amounts promotes physical densification.