Tribological Properties Of Ti And N Ions Implanted 304 Stainless Steel

304 stainless steel usually used for ordinary chemical equipment, food production equipment and nuclear power, which is the one of valuable stainless steel and heat-resting steel in industrial production. However, due to the surface hardness, tribological properties of 304 stainless steel can not satisfy the industrial production requirements in severe environments, the surface modification of 304 stainless steel shows importance of improving its performance. Friction and wear are essentially surface related degradations that can be minimized by surface alloying using ion implantation. In this paper, metal element Ti and nonmetal element N are implanted into 304 stainless steel. The purpose of this investigation is to study the tribological mechanism from the structure and composition of implanted 304 stainless steel.The increase in micro hardness is observed for all the Ti and N ions implanted samples as compared to the unimplanted sample under the load of 0.5 N. The micro hardness increases with the ion implantation doses increase. The micro hardness of the Ti and N ions implanted sample with 7?1017 ions/cm2 was achieved to the maximum value of HV0.02 N ? 320.1 MPa. The wear properties of Ti and N ions implanted samples are better than unimplanted sample under a load of 5 N for a duration of 20 min by dry friction at the speed of 500 r/m, which the sample with the doses of 7?1017 ions/cm2 has the lowest friction coefficient of 0.303 compared with unimplanted sample of friction coefficient of 0.403. The SEM analysis shows that the surface of implanted sample has serious plastic deformation and wider grinding mark under the load of 5 N, however, the surface of implanted samples have smaller width of grinding mark, and the wear extent decreased by 17 %. In addition, the wear mechanism changes from coexistence of adhesion wear and abrasive wear to oxidative wear and adhesion wear. The formation of oxidative wear adhere to scratches in the surface of 304 stainless steel provides some lubrication action, which is the main reason of decreasing friction coefficient at the high doses of Ti and N ions.The microstructure, which is composed of FeCr0.29Ni0.16C0.06 phase in unimplanted sample and TiO₂, TiN phases are observed on the implanted samples by x-ray diffraction (XRD), but the contents and peak intensity of three implanted samples are different. Moreover, the element of titanium has been found peak position at 463.5 eV and 457.8 eV corresponding to TiO₂ and TiN, but the experiment cannot determine the existence of TiON by the significant difference between two peaks of TiON and TiO₂. The element of nitrogen has been found peak position at 399.3 eV and 395.9 eV corresponding to N - O bonding and TiN, From the research , the gradient structure TiO₂– TiON - TiN is formed in the surface of 304 stainless steel.