## 3 Results and Discussion
### The Comparative Analysis of Dry and Moist Friction on the Sliding Layer Formation  
In order to realize the purpose of the work and evaluate the effect of moist rings on the resulting sliding layer, in the first step the obtained roughness values of steel samples were compared with the initial values (Table 4). Next, the results of the surface roughness of steel samples, after working with dry and moist graphite rings, were compiled on the charts (Figures 9 and 10). The results of surface roughness tests after conducting two cycles of work--5 and 30 min--are summarized. \begin{table}
\begin{tabular}{l c c c c c c c c c c c c} \hline \hline \multicolumn{13}{c}{**The Steel Samples Working with Dry Graphite Counter-Samples**} \\ \hline Speed [mm/s] & \multicolumn{8}{c}{25} & \multicolumn{8}{c}{50} \\ \hline Load [N] & 10 & 20 & 30 & 10 & 20 & 30 & 10 & 20 & 30 \\ \hline \multicolumn{13}{c}{Roughness parameters Ra [\(\mu\)m]} \\ \hline  & b * & a ** & b & a & b & a & b & a & b & a & b & a \\ \hline Rest (30 s) & 3.33 & 3.31 & 3.31 & 3.32 & 3.23 & 3.36 & 3.22 & 3.31 & 3.36 & 3.42 & 3.23 & 3.36 \\ \hline Movement (5 min) & 3.57 & 3.99 & 3.47 & 3.91 & 3.49 & 3.61 & 3.45 & 3.56 & 3.41 & 3.61 & 3.33 & 3.20 \\ \hline Movement (30 min) & 3.42 & 3.52 & 3.52 & 2.92 & 3.32 & 3.01 & 3.42 & 3.32 & 3.49 & 2.72 & 3.45 & 2.81 \\ \hline \multicolumn{13}{c}{The steel samples working with moist graphite counter-samples} \\ \hline Rest (30 s) & 3.25 & 3.42 & 3.20 & 3.31 & 3.43 & 3.21 & 3.21 & 3.32 & 3.21 & 3.40 & 3.44 & 3.31 \\ \hline Movement (5 min) & 3.35 & 3.43 & 3.34 & 3.23 & 3.34 & 3.23 & 3.30 & 3.23 & 3.35 & 3.23 & 3.41 & 2.95 \\ \hline Movement (30 min) & 3.25 & 2.99 & 3.45 & 2.72 & 3.55 & 2.65 & 3.20 & 2.49 & 3.55 & 3.25 & 3.52 & 3.42 \\ \hline \hline \end{tabular}  
* b—before experiment, *
* --after experiment.  
\end{table} 
Table 4: The roughness values of steel samples before and after the tests for all operating conditions. Figure 8: Change in the values of the Ra roughness parameters of steel samples mated with moist graphite rings for 30 min under loads of 10, 20, and 30 N and speeds of 25 and 50 mm/s. For the 5-min cycle, the presence of water in the friction node contributed to a faster and greater decrease in surface roughness with respect to the friction node working dry. This trend was evident for both 25 mm/s and 50 mm/s speeds. The increase in speed contributed to a faster smoothing of the surface. During the 30-min operation of the friction node, the presence of moisture did not clearly affect the results. At a speed of 25 mm/s in the friction node working with soaked samples, there was a significantly greater decrease in roughness than for the friction node working dry. On the other hand, at a speed of 50 mm/s, as the load increased, the presence of moisture affected the increase in the roughness of the counter-sample. This phenomenon was not observed for the dry-running counter-sample, where the surface roughness decreased with increasing load. In order to show the differences in the structure of the emerging layer on the steel sample working with the dry and moist graphite counter-sample, photos of selected surfaces, before and after the experiment, working in 5 and 30-min cycles, at speeds of 25 and 50 mm/s and a load of 30 N are summarized (Figure 11). Observational studies of the surfaces of steel counter-samples confirmed the results obtained while examining the surface roughness that the moisture content of the operation of the tested friction node had a strong influence on the resulting sliding layer. The graphite layer that is formed under dry conditions did not always cover the entire surface of the metal counter-sample. The operating time of the friction node, the set load, and the speed were also significant. After 5 min of operation of steel samples with moist  
Figure 10: Comparison of the values of the Ra roughness parameter of samples mating with dry and moist rings for a period of 5 min, for loads of 10, 20, and 30 N, at speeds of 25 and 50 mm/s.