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TRIBOLOGY - LUBRICANTS AND LUBRICATION Part 16

Tham khảo tài liệu 'tribology - lubricants and lubrication part 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 292 Tribology - Lubricants and Lubrication Bath oil force Fig. 5. Scheme of the testing arrangement Cylinder on Plate configuration a and load history b 2.4 Corrosion tests Corrosion tests were performed in a conventional electrochemical cell of three electrodes. The reference electrode used for these measurements was a silver silver chloride electrode SSC 0.207V vs SHE the counter electrode was a platinum wire and the working electrode was the studied surface in each case. The exposed area of the samples was 1.47 cm2. Tests were done at room temperature and under aerated conditions. The aggressive media used was NaCl 0.06M. The electrochemical techniques applied for the corrosion behaviour study were electrochemical impedance spectroscopy in function of immersion time 4 and 24 hours of immersion and potentiodynamic polarization. On the other hand impedance measurements were performed at a frequency range between 100 kHz and 10 mHz 10 freq decade with a signal amplitude of 10 mV. Polarization curves were registered from -0.4V versus open circuit potential OCP and 0.8 V vs OCP at a scan rate of 0.5mV s. 3. Friction and wear behaviour of hard coatings and rubber material The evolution of friction coefficient through time for the different rods is shown in Fig. 6. The steady-state of the coefficient of friction was reached from the beginning of the tests that is the running-in phase is really short. The high values during the first seconds corresponded to the loading phase since the setting of the testing normal load was reached after 50 s. Considering the mean values of the friction curves it was found that in general for the three HVOF coatings the lower the averaged roughness the higher the mean friction coefficient independently of the material of the coating Fig. 7 . The effect of reducing roughness by mechanical surface treatments revealed that lowering rod roughness did not promote the formation of the lubrication film in the interphase rod rubber resulting in