Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : April 22, 2024 - April 23, 2024
To clarify the effect of precipitates on low friction, friction tests and in-situ observation of precipitates on the contact points by reflection spectroscopy were conducted. The thickness of the precipitates was observed and estimated from the reflection spectra measured by reflection spectroscopy. From viscosity measurements of lubricants, it was observed that lubricants containing stearic acid become turbid below a certain temperature and their viscosity increases rapidly. It was also found that the viscosity increase point shifted to the lower temperature side as the stearic acid content increased. Friction tests showed that the lubricating effect decreased at temperatures below the melting point of stearic acid. Oil film analysis showed that stearic acid was abundant in the friction area. The thickness of the oil film was increased from the theoretical value, suggesting that the precipitation of stearic acid contributed to the increase in film thickness. As a result, stearic acid precipitation increased the oil film thickness, suppressed direct contact, and reduced friction. It was also found that smaller content of stearic acid achieved more friction reduction. Oil film analysis revealed that the smaller the stearic acid content, the smaller the thickness of the stearic acid layer in the friction zone, suggesting that there is a significant difference in film structure depending on the stearic acid content.
