Analytical techniques performed on oil samples for lubricated machines can be classified in two categories; used oil analysis and wear particle analysis. Used oil analysis determines the condition of the lubricant itself, determines the quality of the lubricant, and checks its suitability for continued use. Wear particle analysis determines the mechanical condition of machine components that are lubricated. Through wear particle analysis, you can identify the composition of the solid material present and evaluate particle type, size, concentration, distribution, and morphology, thus indicating the machine condition and its predictive maintenance.

The above mentioned techniques are suitable methods for the detection of abnormal wear occurring in internal combustion engines, especially for engines running on different fuels. These techniques provide cheap, fast and easy to use predictive maintenance methods which can replace other conventional methods.

The objective of the present study is to apply wear particle analysis technique as an engine monitoring technique to compare two new and identical engines running on gasoline (Engine 1) and gasoline-ethanol blend (Engine 2). The two engines were tested for a total running period of 850 hours. Spectrometric and ferrographic analysis were used for the comparison where quantitative and qualitative changes in the concentration and size distribution of different particles were analyzed and compared to baseline values.

Results showed an increase of wear rate for the engine running on gasoline-ethanol blend compared to the engine running on gasoline only. Two contents of ethanol were used where 10% content showed a moderate increase of wear rate; however 20% content showed a dramatic increase of wear rate.

The predominant wear particles were the ferrous particles and aluminum particles indicating the wear of piston elements and piston rings. Corrosive wear was also highly remarked which indicates a chemical reaction in the presence of ethanol.

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