Dramatic effect of a small amount of MgO addition on the sintering of Al2O3-5 vol% SiC nanocomposite

Abstract

Adding a small amount of MgO, in the range of a few hundred ppm, into an Al2O3-5 vol% SiC nanocomposite has a dramatic effect on improving the sintered density of the nanocomposite. It was observed that the sintered density of the nanocomposite increases significantly with increasing MgO addition from 0 to 300 ppm. The increase rate slows down and then almost levels off with further increase in MgO content, up to 1000 ppm. More transgranularly fractured alumina grains were observed on the fracture surface of the MgO-doped nanocomposites than that observed on the fracture surface of undoped nanocomposite. The effects of such a small amount of MgO addition on the sintering and microstructural development of Al2O3-SiC nanocomposite may be explained using the arguments which have been documented for the beneficial effects of a small amount of MgO in alumina ceramics. © 1998 Elsevier Science B.V.