磁気ディスクとダイヤモンド触針との間に形成される分子液架橋のばね定数と減衰係数の測定(機械要素,潤滑,工作,生産管理など)

概要

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The spring constants and damping coefficients of molecularly thin liquid bridges of PFPE lubricant forming between a diamond tip and DLC surface of a magnetic disk are estimated by means of regression analysis of tip damping vibration. Two PFPE lubricants having functional end groups (Zdol 2000 and Zdol 4000) with respective thicknesses of roughly 20 nm and 40 nm, were coated on a DLC disk surface in order to form a liquid bridge between the disk and the probe tip. This tip, with an exceptionally small curvature radius of 0.1mm, was in separate experiments both retracted from and extended toward the disk surface in a stepwise motion, and the liquid bridge was made to vibrate at each step. By applying regression analysis to observed waveforms, the spring constant and the damping coefficient of the liquid bridge were estimated within an elongation range from 50 to 800 nm. The spring constant, km, of the liquid bridge had negative values varying from -0.15 to -0.1 N/m. Damping values expressed in the form of frequency-multiplied damping coefficients, c_m×ω, ranged from 0.02 to 0.06 N/m. It is interesting to note that both |km| and c_m×ω decreased with bridge elongation, and after reaching the minimum, those values began to increase.
社団法人日本機械学会の論文
2005-04-25