Facile synthesis of ultrathin NbTe sub(2) nanosheets for enhanced tribological properties as a lubricant additive

Graphite-like bulk NbTe sub(2) powders were prepared by a facile solid phase synthesis process and ultrathin NbTe sub(2) nanosheets were obtained by using wet ball milling induced delamination. The X-ray diffraction analysis illustrated that the reduction of particle size was mainly along the stacking direction of the basal planes without great influence on the short range order of NbTe sub(2) crystals. Scanning electron microscopy, transmission electron microscopy, and atomic force microscope observations revealed that the longitudinal dimension of NbTe sub(2) samples changed into the nanoscale from the larger micron level after mechanical exfoliation. The exfoliated NbTe sub(2) nanosheets had better long-term dispersion stability in paraffin oil than bulk NbTe sub(2). The tribological properties were determined on an UMT-2 ball-on-disk friction and wear tester. The results indicated that the paraffin oil with NbTe sub(2) nanosheets exhibited better lubricating behaviors with the lower friction coefficient and wear rate in comparison with the bulk NbTe sub(2). It was demonstrated that NbTe sub(2) nanosheets could easily enter into a point of friction contact, and form an available tribofilm to prevent the direct contact between counterparts during the friction process. Furthermore, this work shows the potential applications of ultrathin NbTe sub(2) nanosheets in the field of tribology. Ultrathin NbTe sub(2) nanosheets were prepared from bulk NbTe sub(2) by wet ball-milling, and the dispersion of exfoliated NbTe sub(2) nanosheets in paraffin oil exhibits more excellent stability and enhanced tribological properties in comparison with that of pure paraffin oil and base oil with bulk NbTe sub(2).