Structure and Chemistry of Soot and Its Role in Wear of Diesel Engines

Abstract

Environmental regulations to reduce the emissions using exhaust gas recirculation (EGR) have resulted in higher soot level in the crankcase oil of diesel engines. Longer drain intervals have resulted in engines running 80000 kilometers or more before an oil change. This results in longer residence times of EGR soot in the crankcase and other parts of the engine drivetrain. The primary structure of soot from in-cylinder combustion is turbostratic carbon, as soot spends more time in the combustion chamber and in the crankcase it incorporates some of the chemistry of the aged oil as well as debris from the wear processes making the soot more abrasive. This study focuses on the use of multiple tools to examine the nature of soot from different engines of the same type but different age all using the same engine oil and similar duty cycles. This soot is compared with soot derived from a typical EGR diesel engine driven for a period of 80000 kilometers.

Keywords

• tribology
• lubrication
• diesel soot
• transmission electron microscopy
• raman microscopy