Tribological Properties of Titanium Alloy in Water-based Lubricating Process of Hydroxyethyl Cellulose

HEC solutions with varying concentrations were used as lubricants, which were introduced into the friction pairs of Ti-6Al-4V plates and Si3N4 balls. Optical surface profiler and 3D measuring laser microscope were used to measure the surface of plates and balls, respectively. EDS and Raman spectroscopy were used to analyze the chemical composition of the resulting wear scars. The friction tests for the effect of linear speed and solution concentration on the tribology properties of Ti-6Al-4V were carried out on a UMT-2 friction and wear tester. The results show that a super-low friction state (mu approximate to 0.005) is achieved after a long running-in stage. The coefficient of friction (COF) decreases with the increasing linear speed (46.1 similar to 362.7 mm/s). The water will evaporate at high speed (>362.7 mm/s) owing to the heat generated by the friction. In addition, the COF decreases with the increasing concentration (0.25%similar to 2.00%). However, the kinematic viscosity of the lubricant has a significantly negative effect on the COF when the concentration is larger than 2.00%. The surfaces of Ti-6Al-4V are worn with smoothed flats at appropriate speeds and concentrations, which is conducive for forming lubricating films. TiO2 is detected on the scar by Raman spectrum. On the basis of these experimental results, a lubrication model was proposed.