Structure and chemistry of crankcase and cylinder soot and tribofilms on piston rings from a Mack T-12 dynamometer engine test

• Systematic study of chemistry and structure of diesel soot from a Mack T12 test.
• Correlation of the chemistry of crankcase soot and cylinder soot and piston ring tribochemistry.
• HR-TEM was used to examine the structure of diesel soot.

Structure and chemistry of soot extracted from the crankcase and cylinder wall and tribofilms on piston rings of a Mack T-12 engine test were examined. XANES spectra recorded on soot samples indicate the presence of thermo-oxidative and tribochemical decomposition products in engine oil indicative of interaction between piston ring and soot samples. HRTEM indicates the presence of nanoparticles of calcium phosphate compounds, ZnO and Fe2O3 embedded at the surface of the turbostratic soot structure possibly responsible for third body wear. Abrasive grooves were found on the piston ring indicative of abrasive wear mechanism as a dominant wear phenomenon. In addition, significant differences in chemical composition of crankcase soot, cylinder soot and piston ring tribofilms were elucidated.

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