Relationship between the molecular structures of lubricants and their performance at the head–disk interface of hard disk drives

This paper reports the results of constant speed drag tests on disks with four different lubricants using an ultra-high vacuum (UHV) tribochamber equipped with a mass spectrometer (MS). An optical surface analyzer (OSA) is also used to observe lubricant migration. Based on the analysis of the experimental results, we propose that, in the case of diamond-like carbon (DLC)-coated sliders, the durability of a lubricant is dominated by its mobility, its ability to bond to the carbon overcoat and its thermal stability. However, in the case of uncoated sliders, the durability of the lubricant, is dominated by the strength of the lubricant layer formed on the carbon overcoat, the interaction between lubricant molecules and the Al2O3 of the slider surface, the degradation rate of the lubricants caused by catalysis of Al2O3, as well as thermal stability of lubricant. Reaction of Al2O3 with the oxygen atoms in the backbones of the molecules is the dominant factor in their catalytic degradation.