Verification Study of Nanostructure Evolution with Heating Treatment between Thin and Thick Fullerene-Like Hydrogen Carbon Films

Abstract

Fullerene-like hydrogen carbon films with a thin film grown on a NaCl substrate are usually employed to show the nanostructure of films (usually of hundred nanometers thick grown on Si substrates) under high resolution transmission electron microscopy (HRTEM) tests because it is easier floated off, where dependability and reasonability has never been seriously contested. Thus, in this paper, thin and thick hydrogen carbon films have been deposited on NaCl (thin films) and Si (thick films) substrates and annealed under room temperature to 500 °C, of which nanostructures have been investigated by HRTEM, Raman spectroscopy, and X-ray photoelectron spectroscopy, to verify the dependability and reasonability of the NaCl method. The results showed heating induced graphitization but with hydrogen content nearly unchanged. HRTEM results revealed that under annealing of 200, 250, and 300 °C, the curved graphene structures gradually increase in films. However, beyond 400 °C, onions structures are present. However, both Raman and XPS spectra show us that after annealed treatment, for original films, both thin and thick films have the near sp2 bonding content and size, but with the annealing temperature increase, sp2 bonding content increases more quickly for thick FL-C:H films due to the higher internal stress compared to thin films. In one word, the NaCl method used for nanostructure detection for films might be a good choice for an easier and quicker analysis, but it is still insufficient, because the heating effect induced by plasma cannot be ignored.

Tribology Dependence of Annealed a-C:H Films in Dry Air and Methanol Environments

“…The result of the H content is calculated by the following equation where m is the slope of the Raman spectrum. The H atom content of the a-C:H film ranges from 21–23 atom %, which is in accordance with our previous reports . Thus, in the present study, it can be assured that annealing has a negligible impact on the desorption of H atom .…”

“…The H atom content of the a-C:H film ranges from 21−23 atom %, which is in accordance with our previous reports. 28 Thus, in the present study, it can be assured that annealing has a negligible impact on the desorption of H atom . In addition, the sp 2 carbon cluster size (L a ) could be calculated by the following formula…”

The Utilization of Carbon Dioxide to Prepare TiCxOy Films with Low Friction and High Anti-Corrosion Properties

“…It can be concluded that the composition of all samples studied in the present work are nearly unchangeable. Both the lowest C and the highest O composite are present in T3 but the Ti/(Ti + C + O) ratio keeps constant until the target current increases to 1.10 A, where the Ti content increases to about 40 at.% (Table 2), which can be assigned to the sputtering modes variation from transition to metal mode [45,46] and the O/(Ti+C+O) ratio fluctuation can be ascribed to the contamination of the oxygen from open atmosphere during transportation [26,27,29]. Thus, it can be confirmed that the composition has no influence on the friction and anti-corrosion properties.…”

“…It is worth noting that reactive magnetron sputtering technology is a useful way to grow low friction solid films, such as TiN x , CrN x , TiC x and CrC x films and diamond-like carbon films as well as fullerene-like hydrogen carbon films [18][19][20][21][22][23][24][25][26], which show not only low friction or even superlubricity but also high anti-corrosive properties via magnetron sputtering method [27][28][29][30][31]. Further, the so-called metallic oxycarbides MeO x C y , produced by magnetron sputtering, have attracted the interest of materials scientists.…”