## 2 Materials and Methods
Such an analysis was also carried out as part of this work, and sample results of these studies are presented in Figure 2. The microstructure and morphology of the ashes were examined by scanning electron microscopy using a JEOL JSM-6610 LV microscope (JEOL Ltd., Tokyo, Japan). The microscopic examinations revealed significant differences in the shape and morphology of the used powders. Two types of particles were found in the A-1 powder, namely, particles with a spheroidal shape and a small degree of surface development, but also particles with a polyhedral shape and dimensions clearly larger than the dominant spheroidal particles (Figure 2a,b). Powder A-2 was dominated by particles of an irregular shape and a complex geometric surface structure (Figure 2c,d). Nevertheless, particles of a more regular polyhedral shape with clearly marked cleavage planes were less numerous. A common feature of both the analyzed powders was the very large particle size dispersion. For the A-1 powder, the particle size ranged from tenths of a micrometer to over 100 \(\upmu\)m, with particles ranging from 2 to 5 \(\upmu\)m predominating. In turn, in the case of powder A-2, the particle size ranged from tenths of a micrometer to even 150 \(\upmu\)m, with the dominant fraction being particles ranging from 1 \(\upmu\)m to 7 \(\upmu\)m. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Ash**} & \multicolumn{8}{c}{**Element Content, wt\%**} \\ \cline{2-13}  & **SiO\({}_{2}\)** & **Al\({}_{2}\)O\({}_{3}\)** & **P\({}_{2}\)O\({}_{5}\)** & **CaO** & **Fe\({}_{2}\)O\({}_{3}\)** & **K\({}_{2}\)O** & **Na\({}_{2}\)O** & **MgO** & **TiO\({}_{2}\)** & **SO\({}_{3}\)** & **Other** \\ \hline A-1 & 50.76 & 29.50 & 0.30 & 2.72 & 7.62 & 3.12 & 1.73 & 1.52 & 1.30 & 0.83 & 0.67 \\ A-2 & 60.47 & 17.89 & 2.22 & 6.74 & 3.65 & 0.88 & 0.88 & 1 & 0.75 & - & - \\ \hline \end{tabular}
\end{table} 
Table 2: Chemical composition of ashes. Figure 2: _Cont._  
more complex chemical composition was found for the dominant spheroidal particles. In addition to silicon and oxygen, these particles also contained aluminum, and in smaller amounts, Ti, Fe, Na, K, Ca, and Mg. Significant differences in the chemical composition of individual particles were also noted in the case of powder A-2. It was found that the particles characterized by a small specific surface and a polyhedral shape with visible cleavage planes are silica, while the particles with a less regular shape and a larger specific surface are unburnt organic material rich in carbon. The presence of SiO\({}_{2}\) in the analyzed preparation is beneficial as silica is a hard material, thus its presence in the composite should result in an increase in the hardness and wear resistance of the composite layer. A relatively high carbon content in the analyzed powder indicates an insufficient amount of air in the combustion chamber. The presence of carbon may be a problem during FSP because gaseous products may be formed under high-temperature conditions, the presence of which may in turn lead to the formation of material discontinuities in the composite matrix. On the other hand, the occurrence of processes leading to the formation of aluminum carbide cannot be ruled out. Unlike gaseous products, the presence of the hard and highly dispersive aluminum carbide may have a beneficial effect on the properties of the material as well as the course of dynamic recrystallization in the material. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multicolumn{8}{c}{**Element Content, wt\%**} \\ \cline{2-11}  & **C** & **O** & **Si** & **Al** & **Ca** & **Mg** & **Ti** & **Fe** & **Na** & **K** \\ \hline
1 & 67.40 & 23.89 & 2.47 & 2.78 & 1.83 & 0.29 & 0.53 & 0.81 & - & - \\
2 & 13.27 & 44.16 & 42.25 & - & 0.31 & - & - & - & - & - \\
3 & 81.61 & 13.33 & 2.30 & 1.45 & 0.71 & - & - & 0.33 & 0.28 & - \\
4 & 45.41 & 34.84 & 10.81 & 4.63 & 2.43 & 0.21 & 0.37 & 1.15 & - & 0.16 \\ \hline \hline \end{tabular}
\end{table}