Friction control by means of self-assembled nano-lubricant film

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The objective of the research is to understand the tribological phenomenon of HDI, particularly when the head flying height is smaller than 10 nm. The clarification of tribological characteristics of an ultra thin lubricant film on the magnetic disk and the optimum design of the lubricant nanofilm are focused on in this research. Lubricant film must have both adhesive (to solid surface) and fluidic characteristics thus a good lubricant film consists of suitable bonded and mobile layers. The development of ultimate lubrication system is aimed, which is made of bi-monolayer-lubricant film keeping low friction, high durability and high stability against vibration.1.Vapor deposition of strongly bonded hydrocarbon films on amorphous carbon surfacesIt is described that a deposition of strongly bonded hydrocarbon films (1-decanol and decanoic acid) on carbon surfaces by vacuum vapor deposition. From the results of contact angle tests and X-ray photoelectron spectroscopy measurements, we concl … More ude that the hydrocarbon molecules having hydroxyl or carboxyl end groups can be strongly bonded on carbon surfaces by vapor deposition. It is related to the electrostatic interaction between hydroxyl or carboxyl end groups and unsaturated electrons on carbon surfaces. The results of friction measurements are also discussed.2 An effect of autophobicity of PFPE lubricant film on wear propertyThe role of PFPE thin film becomes more important in case that near contact or contact slider is brought about in the actual HDD. It is known that a monolayer film of PFPE with OH or COOH ends fixed on a solid surface exhibits autophobicity and PFPE molecules on the PFPE monolayer cohere and make droplets. The stability of PFPE nano lubricant film is investigated and it is shown that the dewetted surface shows undeairable tribological characteristics such as higher friction and lower lifetime. It is also shown that the observation by microscope shows the droplets of PFPE molecules grows with time.3 Wear process observed by AE methodWe have clarified the frictional characteristics of bonded and mobile layers and proposed their desirable combination as HD lubricants. It was also shown that the lifetime of the PFPE nanolubricant film is strongly affected by the combination of bonded and mobile layer thicknesses. In addition to them we clarified that the frictional trace of PFPE nano lubricant film slid by a small glass ball using pin-on-disk tribotester or spin-stand configurations reflects the wear of mobile layer followed by the wear of bonded layer. We are now focusing on the analysis of the wear process of nanolubricant film using AE measurement using an AE sensor fixed on the glass ball. It is clarified that the wear process of the bonded and mobile films can be distinguished by an elaborate processing of the measured AE data. The results obtained by the AE measurements clarified more the roles of the bonded and mobile layers and emphasize the importance of the combination of them. Less