Effects of Backbone and Endgroup on the Decomposition Mechanisms of PFPE Lubricants and Their Tribological Performance at the Head-Disk Interface

Abstract

Tribo-chemical studies of the lubricant endgroup effect on the tribology of the head-disk interface were conducted using carbon disks coated with PFPE lubricant. The studies involved drag tests with uncoated and carbon-coated Al2O3-TiC sliders in an ultrahigh-vacuum (UHV) tribochamber. The UHV drag tests show that a good lubricant should have one active OH endgroup and one nonactive endgroup. The active one insures the lubricant is adsorbed very well onto the disk carbon surface, resulting in a lower removal rate of the lubricants during the contact sliding. The nonactive one prevents the catalytic decomposition of the lubricant in the presence of the Al2O3 surface of the uncoated slider. The studies also demonstrate that the catalytic degradation process of ZDOL in the presence of Lewis acid occurs most readily at the acetal units -O-CF2-O within the internal backbones (CF2O and CF2CF2O) instead of the endgroup functionals. Therefore, demnum, without any acetal units, experiences less catalytic degradation with the uncoated Al2O3/TiC sliders as compared to ZDOL.