Nanocomposite films of ZrN-Ag were produced by reactive unbalanced magnetron sputtering, and their structural, chemical, mechanical, tribological, haemocompatibility, and antibacterial properties were studied as a function of film composition. The films formed a dense and homogeneous microstructure whereby nanocrystals of Ag are distributed evenly throughout the ZrN matrix. For small additions of silver, the hardness was found to increase, whereas the elastic modulus was found to decrease drastically. In the process of optimizing the deposition conditions, three kinds of coatings were prepared on 316 L surgical steel and tested by accelerated electrochemical polarization tests in order to detect the influence of Ag and the value of the bias potential on the corrosion performance of the system. Films produced under the optimum deposition conditions were, subsequently, deposited on medical grade Ti-Al-V and worn against ball-bearing steel using a ball-on-disk tribotester in bovine serum and were found to have superior tribological properties compared with single-phase ZrN coatings. The haemocompatibility of the films was assessed by investigating the adsorption of human serum albumin and fibrinogen on samples with different phase compositions. Quantification of the protein adsorption was carried out using spectroscopic ellipsometry, which confirmed the haemocompatibility of the films. Antibiotic activity of the films was quantified by incubating the films in bacterial cultures, namely, Staphylococcus epidermis, Staphylococcus aureus, and Escherichia coli. Films with a silver content > 10% exhibited superior antibacterial activity compared with the uncoated samples.

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The present investigation has been carried out with the aim of determining the tribological behavior of a VPS chromium carbide coating both in the as-deposited and heat-treated conditions. A commercial powder of Cr 2 C 3-25% NiCr was sprayed employing a VPS system (Medicoat AG, Switzerland) onto plain low carbon steel coupons. The samples were subsequently annealed for 2 h at 600°C, 800°C and 900°C in Ar. The microstructural characterization was carried out by using SEM and XRD before and after the heat treatment of the samples. SEM observations were employed for determining the degradation mechanisms that took place during the wear tests. When the coated systems rubbed against alumina under a 5 N normal load in air, a progressive change in the mechanism, from a mixed adhesive and abrasive, to a predominant abrasive was observed, as the heat treatment temperature increased. The wear constants were found to be of the order of approximately 10 −6 mm 3 /N.m, which indicates a wear resistance of nearly 4 times higher in comparison with the wear results reported in the literature for similar coating systems obtained by employing HVOF deposition. However, the heat treatment carried out at 900°C brought about only 20% increase in the sliding wear resistance of the coated system.

Los recubrimientos metálicos son métodos ampliamente utilizados para la protección contra la corrosión de aleaciones metálicas, siendo el proceso de cincado por inmersión en caliente uno de los que presenta mayor evolución a nivel industrial. El objetivo de este trabajo es realizar una revisión bibliográfica sobre la influencia de la adición de elementos aleantes en el baño, en la microestructura y en el comportamiento a la corrosión de recubrimientos de zinc obtenidos por la técnica de inmersión en caliente. Se estableció que la composición química de los baños galvanizados influye en las características microestructurales de los recubrimientos y en su comportamiento a la corrosión. La mejora de la resistencia a la corrosión de los recubrimientos de zinc se produce por la adición a los baños de elementos generalmente más activos que el zinc, tales como el magnesio o el aluminio que permiten la formación de capas pasivas que retardan el proceso corrosivo.