## 3 Results and Discussion
### Wear Friction Resistance Test  
For the abrasive wear tests, the samples were prepared according to the standard ASTM G 65 with dimensions of 25 \(\times\) 76 mm. The samples were shaped on an electro erosive cutter. The thickness of the samples (substrate and coating), resulting from the surface modification technique, were different and fell within the range recommended in the standard, i.e., 3.2-12.7 mm. The surface of the samples were initially prepared by grinding in accordance with the recommendations contained in the standard ASTM G 65. The view of the prepared samples (on the example of Alloy 33) for abrasive wear tests is shown in Figure 11a,b, and shows the view of the samples after the wear abrasion test.  
The abrasive wear test was performed in accordance with procedure B, which assumes the pressure of the wheel pressing against the sample at 130 N; the wheel performs 2000 revolutions during the test, which lasts 10 min, and corresponds to the friction distance of 1436 m. Before and after each test, the samples were weighed with a laboratory balance with an accuracy of 0.001 g, and the weight loss \(\Delta\)g was calculated. Two samples of each material were prepared and tested. The result was presented as the mean value of two measurements. The results are presented in Table 5, and the graphic visualization is presented in Figure 12.  
The observed surfaces of investigated coatings (certain samples from Inconel 625, shown for example in Figure 10) have the typical morphology of an abrasive wear resistance test. It was stated that two mechanisms are responsible for the wear of the surface. Except for the expected rolling mechanism [33], the effect of the grooving mechanism was found. This result is from shape-edge abrasive particles, which penetrated deep into the investigated surface. The effect of the penetration was a larger amount of material removed from the specimens, which initiated the grooving mechanism [34]. In contrast to the wear mechanism for the Stellite 6 coating (grooving), the rolling mechanism was predominant in the other investigated coatings.  
Figure 10: Distribution of microhardness in a cross-section of substrate material and the arc sprayed Fe-Al coating, before and after annealing in temperature.  
The presented test results show that the two coatings made of Alloy 33 and Inconel 718 represent the highest abrasive wear resistance. In turn, the worst abrasive wear resistance is demonstrated by the coating produced with Stellite 6. The wear of the Stellite 6 coating  
Figure 11: View of the selected examples of Inconel 625 CMT cladded coatings (**a**) before and (**b**) after the wear resistance test.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Material**} & \multirow{2}{*}{**Sample No.**} & **Weight before** & **Weight after** & **Loss of Weight** & **Average Value** & **Relative 1** **Abrasion** \\  & & **Test, (g)** & **Test, (g)** & **Ag, (g)** & **Ag, (g)** & **Resistance** \\ \hline \multirow{2}{*}{16 Mo3} & 1 & 85,489 & 84.865 & 0.624 & & \\  & 2 & 83.369 & 82.764 & 0.605 & 0.6145 & 0.90 \\ \hline \multirow{2}{*}{Al alloy 33} & 1 & 109.992 & 109.436 & 0.556 & & \\  & 2 & 112.522 & 111.966 & 0.556 & & \\ \hline \multirow{2}{*}{Inconel 718} & 1 & 120.581 & 120.007 & 0.574 & & \\  & 2 & 114.15 & 113.611 & 0.539 & & \\ \hline \multirow{2}{*}{Inconel 625} & 1 & 110.885 & 110.26 & 0.625 & & \\  & 2 & 117.208 & 116.577 & 0.631 & & \\ \hline \multirow{2}{*}{Stellite 6} & 1 & 116.431 & 115.575 & 0.856 & & \\  & 2 & 108.292 & 107.413 & 0.879 & & \\ \hline \hline \end{tabular}
\end{table}
Table 5: The results of the comparison of the abrasive wear of the tested CMT cladded materials.  
Figure 12: Loss of weight of the materials after the abrasive wear test according to ASTM G65.  
in these conditions is about 30% higher than that of ordinary steel used in the construction of boilers.