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In this work the influence of pre-treatment cleaning processes in the adhesion of TiN films deposited by the plasma based ion implantation and deposition (PBII&D) process over plasma nitrided AISI 316L stainless steel was investigated, varying the gas composition, the duration of the sputtering process and the temperature in the same deposition chamber. The TiN film morphology was scrutinized with scanning electron microscopy on the surface complemented with focus ion beam for the cross section. The film microstructure was characterized with X ray diffraction. The adhesion of the coatings was studied using the Scratch Test with constant load at different values and the Rockwell C indentation method as well. It was found that only with the sputtering carried out in a H 2-Ar gas mixing at 300 ºC temperature used as pre-treatment was successful to prepare the nitrided surface for the subsequent TiN deposition by the PBII&D process.

Abstract. In this work TiN and Ti-TiN bilayer coatings obtained with a vacuum arc on AISI 316 samples were proposed in order to improve hardness and tribological properties. The coatings were deposited with a DC cathodic arc running a 130 A current discharge between a Titanium cathode and the vacuum chamber employed as anode. The samples were placed 20 cm away from the cathode surface. TiN films were obtained employing a continuous nitrogen flux of ~ 20 sccm and a working pressure in the range of 3 10 -2 Pa. The structural and tribological properties were characterized by means of an optical microscope, scanning electron microscopy (SEM), x-ray diffraction (XRD), scratch test and fretting. The film thickness was about 0.5µm. Ti-TiN coatings presented better adhesion than TiN coatings and improved the fretting fatigue life compared to the untreated steel. IntroductionThe AISI 316L stainless steel is widely used in chemical, nuclear and food industry as well as in medical implants due to its excellent corrosion resistance and good biocompatibility. However, its low hardness, wear resistance and high friction coefficient limit the potential application of this material [1][2][3].A way of improving the corrosion resistance and the adhesive wear resistance or the friction coefficient could be to coat the surface with a ceramic film like TiN. These kinds of coatings are widely used for hardening cutting tools made of high speed steels [4][5][6]. In particular, cathodic arcs have proved to be very attractive to deposit TiN coatings because they promote the formation of dense nanostructured films with a good adhesion and a very high deposition rate. In cathodic arc devices, an electrical discharge of high current (~100 A) and low voltage (~20 V) runs between two electrodes in a vacuum chamber. From the surface of the metallic cathode, a beam of metallic ions is ejected with energies between 20 -100 eV; the ion current being approximately a 10% of the total discharge current. When a sample is exposed to the plasma, the surface is coated with a metallic film. If a reactive gas flows in the chamber, the substrate is covered with a metallic compound of the cathode material [7][8][9].