FRCU - GIS: Grupo de Ingeniería de Superficies - Artículos

Permanent URI for this collectionhttp://48.217.138.120/handle/20.500.12272/812

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    Characterization of DLC coatings over nitrided stainless steel with and without nitriding pre-treatment using annealing cycles
    (2019-04-02) Dalibón Bähler, Eugenia Laura; Czerwiec, Thierry; Trava-Airoldi, Vladimir Jesús; Ghafoor, Naureen; Rogström, Lina; Odén, Magnus; Brühl, Sonia Patricia
    Amorphous hydrogenated diamond-like carbon (DLC) coatings were deposited using plasma assisted chemical vapour deposition (PACVD) on precipitation hardening (PH) stainless steel. Plasma nitriding has been used as pre-treatment to enhance adhesion and mechanical properties. Chemical and mechanical properties of DLC coatings are dependent on the hydrogen content and so on the relation between sp3 /sp2 bondings. The bondings and the structure of the DLC film change with temperature. In this work, a study of the thermal degradation and the evolution of the mechanical properties of DLC coatings over PH stainless steel have been carried out, including the effect of an additional nitrided layer. Nitrided and non-nitrided steel samples were subjected to the same coated in the same conditions, and they were submitted to the same thermal cycles, heating from room temperature to 600 C in several steps. After each cycle, Raman spectra and surface topography measurements were performed ◦ and analyzed. Nanohardness measurements and tribological tests, using a pin-on-disc machine, were carried out to analyze variations in the friction coefficient and the wear resistance. The duplex sample, with nitriding as pre-treatment showed a better thermal stability. For duplex sample, the coating properties, such as adhesion, and friction coefficient were sustained after annealing at higher temperatures; whereas it was not the case for only coated sample.
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    Influence of the pre-treatments and process temperature on the adhesion of TiN films deposited by PBII&D over nitrided austenitic stainless steel
    (2019-10-28) Vaca, Laura Silvia; Quintana, Juan Pablo; Guitar, María Agustina; Vega, Daniel; Brühl, Sonia Patricia; Márquez, Adriana Beatriz
    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 - 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.