## 2 Materials and Methods  
The first step in the research was to prepare the specimens and develop a set of plasma resurfacing parameters variable on the basis of the initial samples. The samples were then incubated in resin so that metallographic tests and microhardness measurements could be carried out. The metallographic tests are related to the determination of the dilution coefficient, which is important for surfacing technology [22]. The dilution coefficient in welding and surfacing technology refers to the proportion of base material mixed with the filler material in the weld pool. It significantly impacts the chemical composition, mechanical properties, corrosion resistance, microstructure, and wear resistance of the weld or surfaced layer. Controlling the dilution coefficient is crucial for achieving desired material properties and cost efficiency in surfacing applications [22]. The tests were carried out on flat bars made of unalloyed C45 steel with dimensions of 300 \(\times\) 100 \(\times\) 6 mm. The surface of the samples was cleaned and degressed before surfacing. The CastoMag 45554S stainless (Gliwice, Polandsteel wire with a diameter of 1.2 mm was used in the process. The wire was used for welding and surfacing difficult-to-veld steels in protective gas Argon N5.0. It is characterised by a high corrosion resistance, resistance to sudden temperature changes, cracking resistance, and the absence of spatter. The chemical composition is shown in Table 1 based on the Castolin Eutetic manufacturer's (Gliwice, Poland) process card [23]. The surfacing tests were performed on an automated workstation equipped with a Panasonic TM-1400 GIII robot (Gliwice, Poland) (Figure 1), a Castolin Eutectic GAP 2501 DC (Gliwice, Poland) source, and a Castolin Eutectic E52 torch (Gliwice, Poland). The main variable parameters were the intensity of the main arc, the plasma arc voltage, the surfacing speed, the feeding speed of the additional material, and the distance of the torch from the working surface. Table 2 shows the variables identified through preliminary testing. The constant parameters, which remain consistent throughout the process, are shown in Table 3.  
The starting points were obtained after a number of tests to achieve the most stable surfacing possible. All the variable parameters were manipulated so that the surfacing weld stitch was as beneficial as possible. Eighteen samples of five replicates of each whole surfacing stitch were conducted considering the trivalent nature of each variable (Table 4); in order to quantify the influence of the parameter variables, an orthogonal randomised experimental plan as described in the article [24] was used. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Element** & **C** & **Si** & **Mn** & **Cr** & **Ni** & **Mo** & **Nb** \\ \hline Percentage content & 0.035 & 0.800 & 1.600 & 19.500 & 11.500 & 2.800 & 0.700 \\ \hline \end{tabular}
\end{table} 
Table 1: Chemical composition of Castolin Eutetic CastoMag 45554S wire [23]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{4}{c}{**Plasma Surfacing Parameters**} \\ \cline{2-5}  & \multirow{2}{*}{**Arc Intensity [A]**} & \multirow{2}{*}{**Arc Voltage [V]**} & \multirow{2}{*}{**Plasma Surfacing Speed [m/min]**} & \multirow{2}{*}{**Feed Speed of Additional Material [m/min]**} & \multirow{2}{*}{**Torch Distance from Work**} \\ \cline{1-1} \cline{5-5}  & & & & **Medditional Material [m/min]** & **Surface [m/min]** \\ \hline
1 & 160 & 28 & 0.50 & 3.9 & 12 \\ \hline
2 & 160 & 32 & 0.25 & 2.5 & 16 \\ \hline
3 & 160 & 35 & 0.75 & 3.2 & 20 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Plasma surfacing parameters for individual tests. Figure 1: Panasonic TM-1400 GIII robotic plasma surfacing station.