Titanium Surface Micro-machining And Tribological Properties Of Micro-structure In Aqueous Solutions

Four kinds of microstructures were prepared on the surface of titanium alloy by EDM technology (EDM wire cutting and EDM technology).The width and depth of microstructures was optimized, and its effect on the tribological properties of microstructures was studied in de-ionized water and simulated human body fluids. Well-defined surface textures of microstructures of different widths and depths were coated with DLC films, and its tribological properties in de-ionized water and simulated body fluids were also studied by a friction and wear tester.The groove, meshwork surfaces and the copper electrodes were machined by WEDM. Then the microstructures of the copper electrode were copied to the surface of titanium alloy at the electrical parameters of E273. By friction and wear tests, it was found that the microstructures could effectively reduce the friction coefficient at the load of 3N and at the sliding velocity of 0.4m/s, and the friction coefficient decreased as the depths decreased at the groove width of 0.2mm. The meshwork width of 0.15mm could gain the lowest friction coefficient. As the angle of meshwork increase, the friction coefficient increased. The square and diamond could also effectively reduce the friction coefficient, but friction coefficient had no much change as the depths changed. The friction coefficient of the square and diamond gradually reduce with the increasing of the depth at the width of 0.2mm. DLC films deposited on the groove surfaces at 0.15mm width and 0.1mm depth reduced the friction coefficient. The microstructure of square and diamond could not reduce the friction coefficient which was the same as the smooth surface. When the titanium alloy were sliding against Al₂O₃ ball under 0.5N and 0.1m/s, the effect of the microstructures on tribological properties was not obvious.However, the groove and meshwork had a proactive effection on reducing friction coefficient, and the friction coefficient increased as the angle of the meshwork increased. In the simulated human body fluids, the smaller width of grooves and meshworks showed the better effect of the reducing friction coefficient, but the friction coefficient of the larger width of the microstructures was higher than the smooth surface. The microstructure of the squares was no effection on reducing friction coefficient. The diamonds could reduce the friction coefficient but the effection was a little. In de-ionized water the microstructures which deposited DLC film could reduce the friction coefficient, while the microstructures which deposited DLC film increased the friction coefficient in the simulated human body fluids.