A NEW FRICTION-SEIZURE TEST FOR PHOSPHATE STEARATE COATINGS USING CONDUCTIVITY MEASUREMENT

The test involves a rotating cylindrical specimen on which a semi-cyli ndrical slider exerts localized pressure. The specimen and slider are both insulated from holders and are connected to a direct current gene rator. The occurrences of hydrodynamic lubrication, mixed lubrication and seizure at slider-specimen coated interfaces are found to be well related to coating conductivity and to local friction force via voltag e and torque measurements vs. number of specimen revolutions. Evolutio n of the above basic lubrication regimes is analyzed with the new test procedures when considering different time values of acid pickling an d aging first, phosphating treatment second and soaping third. It is c learly shown that conductivity measurements are able to accurately den ote the beginning of mixed lubrication and the onset of seizure when u sing different time values for the above coating sequences.