This paper is published in Tribology Letters, Vol. 24 (1) (2006), Pages 67-76. (© Springer Science + Business Media) 1 High-speed tribology of PFPEs with different functional groups and molecular weights coated on DLC M. Minn a , S.K. Sinha a* , S.-K. Lee b and H. Kondo b a Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576, Singapore e-mail: mpesks@nus.edu.sg b Sony Corp. CNC, Sendai Tec. 3-4-1 Sakuragi, Tagajo-shi, Miyagi-ken, 985-0842, Japan DOI: 10.1007/s11249-006-9146-0 Publication date (web): 13/October/2006 Abstract 1 Introduction 2 Experiment 3 Results and discussions 4 Conclusions Acknowledgments References Abstract In this article, we study the friction and wear durability of perfluoropolyether (PFPE) with different functional groups and molecular weights (MW) for a range of disk rotational speeds (500–7200 rpm or 1.2–17.33 m/s). A 4 mm diameter silicon nitride ball under a normal load of 4 g was employed as slider against PFPE lubricated diamond like carbon (DLC) film on magnetic hard disk. The coefficient of friction increases with increasing speeds, to certain extent, but it decreases for the higher speeds. At very high speeds, the fluctuations in the coefficient of friction of low MW PFPEs were larger than those of high MW PFPEs. The optical microscope image of the ball after sliding showed that evaporation might have occurred more easily in low MW than in high MW when sliding speed was increased due to the frictional heat generated at the interface. The wear lives of Z-lube (carboxyl group at both ends) and Z-dol are significantly higher than AS1 (alkoxy silano group at both ends) at low speed (1.2 m/s). In comparison to low MW PFPEs, high MW PFPEs show better wear durability at higher rotational speeds. KEY WORDS: Head Disk Interface (HDI), high-speed tribology, PFPE