ION-IMPLANTATION OF TIN FILMS WITH CARBON OR NITROGEN FOR IMPROVED TRIBOMECHANICAL PROPERTIES

In the held of engineering materials, the study of titanium nitride (T iN) films has attracted great interest because of its unique combinati on of properties. This paper is concerned with the implantation of nit rogen or carbon ions into TiN films to evaluate and obtain the optimum conditions for increased tribological resistance. A commercially avai lable titanium nitride coating produced by ion plating, of approximate ly 3.5 mu m thickness, was treated by implantation of nitrogen or carb on ions at energies of 100 and 75 keV, respectively. The dose range wa s between 5 x 10(16) and 1 x 10(18) ions cm(-2) It has been observed t hat a suitable implantation procedure can lead to a maximum hardness i mprovement of about 15%, as evaluated with a dynamic micro-indentation method at loads from 0.4 to 10 mN. Wear tests performed on an unlubri cated reciprocating apparatus, using an alumina ball with a load of 9. 8 N and at a speed of 150 cycles min(-1), showed that implantation of nitrogen and carbon can reduce wear by 22% and 42%, respectively. Smal l-area X-ray photoelectron spectroscopy (SAXPS) was used to evaluate t he concentration of implanted elements as a function of depth. The ana lysis showed that in the high-dose C+-implanted sample a very high per centage of the carbon remained as pure carbon, whereas in the lower-do se Cc-implanted sample the carbon stayed mainly in a carbidic form. In the case of nitrogen implantation, no large variations in the state o r concentrations were recorded.