ナノ閉じ込めされた液体潤滑剤の粘弾性特性の周波数依存性(機械要素,潤滑,工作,生産管理など)

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When a liquid is confined in nanometer-scale gaps, it exhibits characteristic viscoelastic properties that are different from those properties measured in a bulk state. In hard disk drives, a liquid lubricant film whose thickness is around 1-2 nm is used to lubricate the interface between the magnetic head and the magnetic disk surface. When the magnetic head touches the disk surface, the lubricant film is confined in the nanometer-scale gaps and sheared. In order to attain the proper lubrication, it is essential to investigate the dynamic viscoelasticity of the confined liquid lubricant under shearing motion. In this study, we focused on one of the typical phenomenon of the confined liquid which is referred to as the shear thinning. The shear thinning is the property whereby the viscosity of the liquid decreases when the shear rate or shear frequency increases. This can be observed in many lubricants in a bulk state. The characteristic behavior of the confined lubricant is that the shear thinning can be observed at much lower shear rates or shear frequencies compared to the shear thinning occurs in a bulk state. The mechanism of the shear thinning in the confined state must be different from that of the bulk state. In order to clarify the shear thinning mechanism of the confined lubricant, we measured the gap dependence of the viscoelasticity at different shear frequencies in a range of 100 Hz to 2 kHz. The experimental results showed that the shear thinning behavior suddenly appeared at gap width of approximately 15 nm or less. Further, the shear thinning synchronized with the enhancement of the elasticity which means the solidification of the liquid lubricant.
社団法人日本機械学会の論文
2008-04-25

ナノ閉じ込めされた液体潤滑剤の粘弾性特性の周波数依存性(機械要素,潤滑,工作,生産管理など)

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