## 4 Discussion  
The conducted studies clearly indicate that the working environment has a significant impact on the tribological processes occurring in the expanded graphite-alloy steel combination. One of the key phenomena associated with friction in this tribological pair is material transfer. This mechanism involves the transfer of graphite particles to the steel surface, which can consequently lead to a change in the conditions of cooperation of the system from the initial graphite-steel contact to graphite-graphite contact. The transfer of material takes place under the influence of mechanical and adhesive interactions resulting from the interaction of micro-uniformities of friction surfaces. The characteristics of the graphite layer formation process depend on the operating conditions and can affect the friction and wear parameters of the combination elements to varying degrees. Analysis of the chemical composition showed that in combinations operating in a humid environment, the concentration of carbon on the steel surface was higher, with its highest content recorded under low load conditions. In contrast, an inverse relationship was observed in dry conditions, with a higher amount of carbon accumulating on surfaces subjected to higher loads. In addition, EDS analysis showed that in humid conditions, the amount of oxygen on the tested steel surface increased three times compared to dry conditions. Researchers [PERSON] et al. [39] confirm that the presence of water in the tribological pair significantly increases the amount of oxides in the surface layer. The amount of water introduced into the graphite-steel pair is crucial for their tribological properties. Studies conducted by [PERSON] et al. [43] have shown that a coating containing graphite most effectively reduces friction and wear at relative humidity levels of 55% and 95%. Water molecules adsorbed on graphite act as a lubricant, allowing its layers to slide freely. However, at 95% humidity, graphite agglomeration occurs, causing excessive adhesive wear, \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \multirow{2}{*}{**Load [N]**} & \multirow{2}{*}{**Conditions**} & \multirow{2}{*}{**No.**} & \multicolumn{6}{c}{**Element At. [\%]**} \\ \cline{3-8}  & & & **C** & **Fe** & **O** & **Si** & **S** & **P** \\ \hline \multirow{2}{*}{200} & dry & 1 & 9.88 & 84.27 & 4.31 & 0.54 & 0.19 & 0.08 \\ \cline{2-8}  & humid & 2 & 83.97 & 4.19 & 11.27 & 0.15 & 0.09 & 0.16 \\ \hline \multirow{2}{*}{650} & dry & 3 & 18.57 & 75.48 & 4.29 & 0.5 & 0.23 & 0.17 \\ \cline{2-8}  & humid & 4 & 27.63 & 58.26 & 11.0 & 0.88 & 0.23 & 1.02 \\ \hline \end{tabular}
\end{table} 
Table 4: EDS results of the alloy steel surface after friction cycle, depending on working conditions and load. shortening the durability of the layer compared to conditions at 55% humidity. In this case, water molecules can act as a binder, causing the graphite particles to bond together. The performed research confirms that the presence of water affects the decrease in COF (Figure 3) while simultaneously leading to an increase in wear (Figure 8). In the conducted studies, in humid conditions, cyclical changes in COF are observed. At a load of 200 N, after an initial decrease in friction, a temporary increase in its value is observed, followed by stabilization at the initial level. This mechanism can be explained by the change in humidity in the tribological pair, resulting from the friction process. Researchers [PERSON] et al. [44] and [PERSON] et al. [45] state that the amorphous carbon structure features a large number of edges and dangling bonds, which can easily interact with water molecules. Repeated destruction and formation of this amorphous carbon structure lead to fluctuations in the friction coefficient. Moreover, under high relative humidity, water molecules have more opportunities to passivate dangling bonds, thereby lowering the friction coefficient of the material.