Tribological performance of PFPE and X-1P lubricants at head–disk interface. Part I. Experimental results

X-1P, a cyclic phosphazene lubricant, is studied and compared with polar perfluoropolyether (PFPE) lubricant Z-Dol. Contact angles of lubricants are measured on different solid surfaces. Contact start-stop (CSS), drag, and ball-on-flat tests are performed and the results are discussed. Drag tests under high vacuum are also performed and discussed. Experimental results show that lubricant X-1P exhibits lower static friction and higher durability than lubricant Z-Dol, especially at high humidity. Higher durability is also observed for X-1P under the high vacuum condition compared with lubricant Z-Dol. Diamond-like carbon (DLC) overcoat on the Al2O3–TiC slider surface lowers friction and prolongs durability, especially for lubricant Z-Dol at high humidity, whereas for X-1P, there is no benefit of DLC. X-1P as an additive shows some improvement in durability at high humidity as compared to lubricant Z-Dol.