DRAMATIC EFFECT OF A SMALL AMOUNT OF MGO ADDITION ON THE SINTERING OFAL2O3-5 VOL-PERCENT SIC NANOCOMPOSITE

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 t he sintered density of the nanocomposite. It was observed that the sin tered density of the nanocomposite increases significantly with increa sing 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 100 0 ppm. More transgranularly fractured alumina grains were observed on the fracture surface of the MgO-doped nanocomposites than that observe d on the fracture surface of undoped nanocomposite. The effects of suc h a small amount of MgO addition on the sintering and microstructural development of Al2O3-SiC nanocomposite may be explained using the argu ments which have been documented for the beneficial effects of a small amount of MgO in alumina ceramics. (C) 1998 Elsevier Science B.V.