Tribological Behavior of Porous Titanium after Thermal Oxidation

We study the tribological behavior of porous commercially pure titanium synthesized by the method of powder metallurgy and operating in a friction couple with tool steel under the conditions of boundary lubrication. It is shown that the presence of porosity promotes the increase in the wear resistance of titanium as compared with nonporous titanium obtained by using the traditional technology. Open pores appearing on the titanium surface serve as additional reservoirs for lubricants and supply them, in the course of friction, into zone of tribocontact, thus decreasing the intensity of wear according to the adhesive mechanism. The process of thermal oxidation of porous titanium decreases the friction coefficient and intensity of wear of the tribocouple by 34 and 24%, respectively, due to the formation of a surface chemically inert oxide (TiO 2 ) film with high microhardness.