Fluctuations of the elemental composition in the layers of mineral deposits formed on the elements of biogas engines.

The aim of the research was to compare the chemical composition and morphology of the surface of the backsheet growing on the metallic and surface substrate growing already on the prepared mineral substrate. Moreover the aim of this study was also to analyze the dispersion of chemical elements on the cross-sections of deposits formed on parts of landfill biogas-driven engines. The chemical composition of extreme layers of mineral deposits extracted from the engine piston and their cross-sections from four pistons and one head was examined by SEM-EDS. The bottom side showed a much smaller heterogeneity of the topography of the surface than the topside. The chemical composition of the deposit bottom side it primarily S (41%), Si (34%) and Al (17%). In the case of the top side, the dominated of Ca (52%) with a relatively high share of S (32%) and Si (14%). The presence of P and Mg it was also found, but only on the bottom side, and the share of Fe and Zn only on the top side. In the case of cross-sections, Ca, S and Si were the dominant elements. In general, there were higher Si participations in the zone of the bottom layer with a downward trend to the top sheet. The mass shares of S and Ca were lower in the zone of the bottom layer with the upward trend to the top sheet, also undergoing fluctuation.