The Effect of Temperature on Lubrication Property with MoDTC-Containning Lubricant Temperature Dependence of Friction Coefficient and Tribofilm Structure

• Published in: Tribology Online Vol. 13; no. 5; pp. 275 - 281
• Main Authors: Komaba, Masanori, Kondo, Shinya, Suzuki, Atsushi, Kurihara, Kazue, Mori, Shigeyuki
• Format: Journal Article
• Language: English
• Published: Tokyo Japanese Society of Tribologists 15.12.2018; Japan Science and Technology Agency
• Subjects: Chemical analysis; Coefficient of friction; Friction; friction coefficient; high resolution transmission electron microscopy; layer structure; Lubricants; Lubricants & lubrication; Lubrication; Lubricity; Maintenance management; Molybdenum; Molybdenum disulfide; Molybdenum dithiocarbamate; molybudenum dithiocarbamate; Organic chemistry; Photoelectrons; Steady state models; Temperature; Temperature dependence; Temperature effects; Transmission electron microscopy; tribo chemistry; tribofilm; X ray photoelectron spectroscopy
• ISSN: 1881-2198; 1881-218X; 1881-2198
• DOI: 10.2474/trol.13.275

The effect of temperature on the lubricity of molybdenum dithiocarbamate (MoDTC) was investigated by a ball on disk tribometer with lubricant oil containing MoDTC and calcium sulfonate (CaSU) at temperatures of 25˚C, 40˚C, 60˚C and 80˚C. The behavior of friction coefficient was closely dependent on the oil temperature. Friction coefficient decreased after a certain induction period and became to be constant at steady state. At higher temperature, the induction period became to be shorter, and the slope of decreasing friction coefficient became to be steeper. Friction coefficient at steady state decreased at higher temperature, and was changed reversibly when the oil temperature was changed. Oscillatory change in friction was observed when the oil temperature was changed periodically. Chemical analysis of the tribofilm with X-ray Photoelectron Spectroscopy (XPS) revealed that higher content of Mo(IV) as a component of molybdenum disulfide (MoS2) was observed in the tribofilm formed at higher temperature. Highly oriented MoS2 layer was observed with High Resolution Transmission Electron Microscopy (HR-TEM) in the tribofilm formed at 80˚C. It was found that the structure of tribofilm is altered reversibly with oil temperature. A steady state model of tribofilm formation was proposed on the basis of observed results.