13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- point in kJ/mol can be considered as the activation energy Ea in Eq. (3). Since worn depth of failure devices is about 100-150nm as a constant, the life-time tl in each vapor environment is theoretically expressed by - ) 0.1744 ) ( lg ( / _ Δ Δ × = ethanol l ethanol lt t . (7) Figure 8 shows the experimental relationship of tl and Δ of vapors in Fig. 4. Two approximate linear regions are found, one consists of water and fluoroalcohols with the slope of 0.05 and the other includes fatty alcohols with the slope of 0.01. The deviation of the slope from 0.1744 to 0.05 in Region II can be expressed by the non-corrosive stage of the initial wear. And for fatty alcohols, the significant deviation from the theoretical expectation suggests that only the thermal- and tribo- solvolysis is not able to give a full explanation of the tribo-reactions. Figure 7. The DFT calculation results of Eb and ΔE. Δ: The reference point, ○: Volatile solvent, ●: Less volatile solvent. Dashed lines are used to guide the sight: along the straight line from top right to bottom left - the reference point, trifluoroethanol, 2-methoxyethanol, propanol, pentanol, hexanol, octanol and propylene oxide, along the arc line from top left to bottom right - tetrafluoropropanol, glycol, isopropanol, ethanol, methanol, 2-methoxyethanol, water and phenol. Figure 8. The relationship of life-time test and Δ. From left to right: Region I - propylene oxide, hexanol, propanol, methanol, ethanol and isopropanol, Region II – water, tetrafluoropropanol and trifluoroethanol.
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