## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c} \hline \hline
**26** & **FWMH (\({}^{\circ}\))** & **Grain Size (nm)** \\ \hline
11.88 & 0.18 & 46.33 \\
14.52 & 1.06 & 7.89 \\
16.76 & 0.96 & 8.73 \\  
In Figure 6, similar structures are seen on the surface of SC with wrinkles and crumbles [50; 51]. Larger GO clusters were observed due to the absence of N\({}_{2}\) during the coating process entailing a decrease in the sp\({}^{3}\)/sp\({}^{2}\) ratio and the clustering of carbon in the various regions of the surface [52]. AFM imaging was utilized to investigate the surface morphology of the substrates, using a scan size of 5 \(\upmu\)m \(\times\) 5 \(\upmu\)m, as seen in Figure 7. The images clearly depict that the grooves and asperities of the surfaces were filled with carbon composites, i.e., CNT and GO. Referring to the images of both samples, the surfaces were generally dominated by  
Figure 5: SEM images of the coated surface of SCN. Figure 6: SEM images of the coated surface of SC. GO structures, and CNT structures were also observed throughout the sample surfaces. The SEM images also confirm this phenomenon. Considering the fact that the coating was made from a very close distance to the plasma gun (10 mm), and given the variability of the incidence angle due to the rotating mechanism, the sample surface enabled the uniform formation of carbon structures even on a very rough metal surface, as shown in Figures 5-7. The plasma flux with variable angles provides enhancement in terms of the continuity and atomic order of carbon structures throughout the surface. The surface topography and coating thickness data of the SCN are shown in Figure 8a. It was observed that the mean coating thickness was found to be 5 \(\pm\) 1 \(\upmu\)m, and the amount of tight carbon clusters was higher than those of the SC. For SC, the average coating thickness was found to be around 10 \(\pm\) 1 \(\upmu\)m. The lower number of carbon islands, in general, increased the size of the carbon heaps, which is consistent with the other analyses. Figure 7: Cont. The elemental compositions of the coated substrates are demonstrated in Table 6. Carbon deposition on both substrates is clearly seen from the EDX analyses. Referring to a previous study [5], the C-C bonds were prone to becoming stronger as the nitrogen amount in the plasma was adjusted at about 8-12 sccm. Due to the higher amount of N\({}_{2}\) during the deposition process, the carbon amount throughout the surface of the SCN was observed to be lower when compared to that of the SC, as shown in Figure 9.  
The hardness values of carbon-based materials are predominantly determined by the strength and brevity of the carbon bonds; therefore, an increased sp\({}^{3}\)/sp\({}^{2}\) ratio corresponds to enhanced hardness [53]. The AFM and optical microscopy images (Figure 10) indicate that the coating on the surface of SCN maintained its uniform structure better than that of SC despite the severe abrasion test conditions. An optimal blend of N\({}_{2}\) and CH\({}_{4}\) yields enhanced hardness and a more polished surface, resulting in superior durability and better resistance to abrasion. Deposition factors exert a substantial influence on the mechanical and tribological properties of the structure. SCN has a notably higher abundance of preserved carbon clusters compared to SC, suggesting that its surface structure exhibited higher endurance during the abrasion tests. Figure 10a,b depict the worn surface morphology of SCN, and it is clearly visualized that the abrasion ball was not even able to scratch the region where the diamond structure (only one of many diamond regions was depicted) was formed due to its higher hardness than that of the scratcher. The absence of a scratcher trace is also confirmed by the AFM image of the diamond region (Figure 10b). The incorporation of N\({}_{2}\) gas into the plasma enhanced the adhesion of the carbon to the substrate, which is also consistent with the other tribological analyses.