Degradation of perfluoropolyether lubricants on magnetic recording disks during sliding

Proceedings of the Institution of Mechanical Engineers, Part J:

2001

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The decomposition mechanisms of the perfluoropolyether (PFPE) lubricants have been studied through calculation of chemical reaction kinetics and several experimental approaches. Four degradation mechanisms were considered: thermal and catalytic decomposition, triboelectrical decomposition and mechanical scission. The results show that the effect of catalytic reaction on the degradation of the PFPE lubricants is negligible in sliding conditions because of the short contact time, small contact area and low interface temperature. Illumination with ultraviolet light is found to accelerate the decomposition of the lubricant, reducing the head-disk interface durability and causing more gaseous fragments because lowenergy electrons created by the illumination interact with the lubricant molecules, activating and breaking up the molecules. A decomposition mechanism of the lubricant from the effect of low-energy electrons is proposed. Mechanical shear is also found to have an important effect on the decomposition of the lubricant. The partial pressures of the gaseous fragments of the lubricant increase rapidly with increase in the sliding velocity. The temperature from ambient up to 70 8C has no obvious effect on the decomposition of the PFPE lubricant, although higher temperatures are expected to be detrimental. Dominant degradation mechanisms in the sliding conditions are triboelectrical reaction and mechanical scission.

Section: Experimental Apparatus Uv Lamp and Test Proceduresmentioning

confidence: 99%

Studies on degradation mechanisms of lubricants for magnetic thin-film rigid disks

Proceedings of the Institution of Mechanical Engineers, Part J:

2001

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“…The tribotester features a mass spectrometer with its ionization chamber located in the line of sight of the slider±disk interface so that emission from the interface can be monitored in situ during the sliding under a high vacuum. A detailed description and an overall schematic diagram of this apparatus can be found in references [16] and [20]. In order to examine the effects of UV irradiation on the PFPE lubricants, a UV lamp was installed in the vacuum chamber and over the slider±disk interface at a distance of about 50 mm.…”

Section: Experimental Apparatus Uv Lamp and Test Proceduresmentioning

confidence: 99%

Lubrication studies of head-disk interfaces in a controlled environment Part 2: Degradation mechanisms of perfluoropolyether lubricants

Proceedings of the Institution of Mechanical Engineers, Part J:

Kajdas

2000

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The decomposition mechanisms of the perfluoropolyether (PFPE) lubricants were studied in this paper using several experimental approaches. The PFPE lubricant film can be bonded to disk surface by illuminating the lubricant film with ultraviolet (UV) light; then the durability of the head±disk interface can be improved. However, during the sliding process, the illumination with UV light can accelerate the decomposition of the lubricant, reducing the head±disk interface durability and causing more gaseous fragments because low-energy electrons created by the illumination interact with the lubricant molecules, activating and breaking up the molecules. A decomposition mechanism of the lubricant with the effect of low-energy electrons was proposed. Mechanical shear is also found to have an important effect on the decomposition of the lubricant. The partial pressures of the gaseous fragments of the lubricant increase rapidly with increase in the sliding velocity. No obvious effect of ambient temperature up to 70 8C on the decomposition of the PFPE lubricant was observed, although higher temperatures are expected to be detrimental.

“…The sliding experiments were carried out in a high-vacuum environmental tribometer [10,11]. It features a mass spectrometer with its ionization chamber located in the line of sight of the slider±disk interface so that emission from the interface can be monitored in situ during sliding under the high vacuum.…”

Section: Test Apparatusmentioning

confidence: 99%

Lubrication studies of head-disk interfaces in a controlled environment: Part 1: Effects of disk texture, lubricant thermal treatment and lubricant additive on the durability of the head-disk interface

Proceedings of the Institution of Mechanical Engineers, Part J:

2000

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Decomposition and tribological performance of Z-Dol and X-1P lubricants on the magnetic recording thin-film disks are studied during sliding in a high-vacuum environment. Gaseous products generated from the head±disk interfaces and frictional force are detected and monitored as functions of the sliding distance by using a quadrupole mass spectrometer and friction measurements. The thin-film disks with mechanical and laser texture were used and different thermal treatments were applied to the lubricant films. The effects of the disk texture, lubricant thermal treatment and lubricant additive on the degradation and durability of head±disk interface, are studied in detail. Experimental results show that, firstly, fluorocarbon fragments are generated from lubricants during a period of sliding with a low and stable coefficient of friction, followed by a sharp rise in the frictional force and generation of gaseous products of diamond-like carbon overcoat material. The disk texture has effects on the decomposition of the lubricant and durability of the head±disk interface; the laser-textured disk surface caused Z-Dol lubricant to decompose at lower sliding distances and with more gaseous species compared with the mechanically textured disk. Thermal treatment of the lubricant films and the application of X-1P as an additive to the ZDol lubricant improved the durability of the head±disk interfaces.