Researchers study mechanical performance of MoS2 and WS2 nanostructures
Scientists at the Ohio State University studying the mechanical performance of MoS2 and WS2 nanostructures have published their research in Nature Scientific Reports.
Nano-objects are of interest for drug delivery, oil detection, contaminant removal, and tribology applications. In some of these applications, they are likely to be subjected to friction and deformation during contact with each other and their surfaces on which they slide. To date, experimental studies directly comparing local and global deformation are lacking.
The researchers performed nanoindentation (local deformation) and compression tests (global deformation) with a nanoindenter (sharp tip and flat punch, respectively) on MoS2 multi-walled nanotubes (MWNTs), ~500nm in diameter. They also did compression tests on WS2 MWNTs, ~300nm in diameter and carbon nanohorns (CNHs) 80-100nm in diameter.
They discovered that hardness performance of the MoS2 nanotube was similar to bulk and did not follow the "˜smaller is stronger' phenomenon as previously reported for other nano-objects. For compression, highest loads were required for WS2 nanotubes, then MoS2 nanotubes and CNHs to achieve the same displacement. This was due to the greater number of defects with the MoS2 nanotubes and the flexibility of the CNHs. Repeat compression tests of nano-objects were performed showing a hardening effect for all three nano-objects.
The researchers believe the studies will aid in understanding the mechanisms involved during global deformation when nano-objects are introduced to reduce friction and wear.
'Nanomechanical behavior of MoS2 and WS2 multi-walled nanotubes and Carbon nanohorns' by D. Maharaj and B. Bhushan, Scientific Reports 5, Article number: 8539 doi:10.1038/srep08539
