Densities of the sintered cutting inserts were measured using the
Archimedes principle. Fig. 3 shows the densities of ZTA–MgO cutting
inserts with different MgO particle sizes. A maximum density of
4.31 g/cm3 was obtained by the sample with 80 nm MgO as additives.
A study by Lumley and Schaffer [10] indicated that by using a coarse
particle as an additive, it will result in a highly localized and poorly
distributed liquid. Thus, the efficiency of the additive is limited since it
only affects certain areas of the matrix [10].