Voltage assisted asymmetric nanoscale wear on ultra-smooth diamond like carbon thin films at high sliding speeds

Abstract

The understanding of tribo- and electro-chemical phenomenons on the molecular level at a sliding interface is a field of growing interest. Fundamental chemical and physical insights of sliding surfaces are crucial for understanding wear at an interface, particularly for nano or micro scale devices operating at high sliding speeds. A complete investigation of the electrochemical effects on high sliding speed interfaces requires a precise monitoring of both the associated wear and surface chemical reactions at the interface. Here, we demonstrate that head-disk interface inside a commercial magnetic storage hard disk drive provides a unique system for such studies. The results obtained shows that the voltage assisted electrochemical wear lead to asymmetric wear on either side of sliding interface.

Galvanically induced potentials to enable minimal tribochemical wear of stainless steel lubricated with sodium chloride and ionic liquid aqueous solution

“…The hypothesis of this work is based on two tribological mechanisms which arise due to the interaction of ionic molecules on a polarized interface. On the one hand the steel surface is electrochemically protected against corrosion reactions [32,33]. On the other hand the polarized surface in combination with ionic molecules can lead to the formation of very stable interfacial layer as it was shown using AFMmeasurements [20].…”

“…But it must be noticed that water can strongly change viscosity, polarity, and surface tension in contrast to the pure IL [46]. Consequently, understanding surface interactions, tribochemistry and electro-chemical phenomena and ordering of molecules on the tribological interface are identified as key factors to realize tribological applications using aqueous lubricants [32]. Both factors, the good miscibility with water and the capability to adsorb with a high packaging density were decisive that 1-ethyl-3methylimidazolium chloride ionic liquid [C 2 mim][Cl] was used for this investigation.…”

Electrostatically Tunable Adhesion in a High Speed Sliding Interface

“…Maintaining good tribological properties such as low wear and stiction of such a high speed sliding interface at low clearance is critical for the long term reliability of hard disk drives [7]. Any contact between the head and the disk leads to friction and wear of the head overcoat layer, adversely impacting the disk drive performance [8][9][10][11].…”

“…The electrostatic force is an attractive force which reduces the fly height (parabolic dependence) until the pull-in threshold is reached [11,20]. At this point the effective stiffness becomes singular, and the slider thermal actuator makes contact with the disk.…”

“…Maintaining good tribological properties such as low wear and stiction of such a high speed sliding interface at low clearance is critical for the long term reliability of hard disk drives [7]. Any contact between the head and the disk leads to friction and wear of the head overcoat layer, adversely impacting the disk drive performance [8][9][10][11].A unique way of reducing the friction during contact is through externally imposed oscillations of small amplitude and energy. Previous experimental and theoretical work to reduce the friction at a sliding interface explored the use of external excitation with either surface acoustic waves or electrostatic forces to modulate the out-of-plane or in-plane motion [12][13][14][15].…”