| Summary: | In this project, three amorphous carbon samples are generated with the REBO, AIREBO and modified AIREBO potentials respectively. Three indentations at different depths are done on each sample. The aim of this project is to explore how different factors such sp3 ratios or indentation depths can affect the micro-hardness value. The results show that micro-hardness levels are higher with lower depths of indentation, extending the indenter size effect observed on the sub-micron level to the sub-nanometre level. The median micro-hardness values of about 72 GPa, 132 GPa and 121 GPa for the REBO, AIREBO and modified AIREBO samples respectively, are however significantly higher than experimental values for the same sp3 ratio. Further analyses suggest that this is due to the higher densities of the samples produced by the REBO and AIREBO samples for the same sp3 ratio. Other factors are also possibly present which explain for the higher micro-hardness values observed for the modified AIREBO sample. These factors, though insignificant at the nanometre scale, is significant at the sub-nanometre indent depth levels.
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