Polishing Behavior and Surface Quality of Alumina and Alumina/Silicon Carbide Nanocomposites

Abstract

The response of Al2O3 and Al2O3/SiC nanocomposites to lapping and polishing after initial grinding was investigated in terms of changes in surface quality with time for various grit sizes. The surface quality was quantified by surface roughness (Ra) and by the relative areas of smooth polished surfaces as opposed to rough as‐ground areas. Polishing behavior of the materials was discussed in terms of SiC content and grain size. It was concluded that nanocomposites are more resistant to surface damage than Al2O3, and this behavior does not depend on the amount of SiC in the range 1–5 vol%. SiC addition ≥1 vol% is enough to produce a noticeable improvement in surface quality during lapping and polishing.

An indentation model for erosive wear in Al2O3/SiC nanocomposites

“…[8][9][10][11][15][16][17] The erosive wear rate is reduced when SiC is added either with or without the sintering aid addition. Wear rate in Al 2 O 3 is always dependent on grain size 13 so some caution has to be exercised to ensure that the improvement in wear rate is not simply because of grain size refinement (Table 1) due to grain boundary pinning by SiC.…”

Effects of Y2O3 additives and powder purity on the densification and grain boundary composition of Al2O3/SiC nanocomposites

“…10 Interestingly, improvements in wear properties of nanocomposites over those of alumina have also been found when studying materials made with impure "easy sintering" alumina (Sumitomo AES 11c) which contains SiO 2 (0.04%), Na 2 O (0.03%) and MgO (0.04%). 9 This indicates that there is a change in properties when SiC is added even when compared to an alumina which would already be expected to have significant grain boundary segregation.…”

“…Hence, the nanocomposites tend to have significantly finer grain sizes when fully dense than Al 2 O 3 . 9,16,17 Genuine improvements in properties can then be achieved simply by grain-refinement.…”

Microstructure and mechanical properties of Al2O3 matrix nanocomposites produced by solid state precipitation

“…This is in complete contrast to the samples developed by aging for shorter duration (≤20 h) at 1450 • C, which can be polished to a better surface finish and more easily than monolithic Al 2 O 3 , as is the case for Al 2 O 3 -SiC nanocomposites. 7,22,23 The percentage of the volume occupied by the secondary phase in the Al 2 O 3 -FeAl 2 O 4 'nanocomposites', as determined from BSE-SEM images via point counting, are plotted as functions of aging durations for the different aging temperatures in Fig. 7.…”