Browsing by Author "Corengia, Pablo"
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Item Microstructural, mechanical and tribological properties of CrA1YN coatings deposited by magnetron sputtering(2009) Brizuela, Marta; García-Luis, Alberto; Corengia, Pablo; González-Santamaría, Daniel; Muñoz, Roberto; González, Javier Jesús; INGENIERÍA DE SUPERFICIES; TECNOLOGÍAS DE HIDRÓGENO; GENERALCrAlYN coatings were synthesized by reactive magnetron sputtering. The aim of this research is to study the influence of the nitrogen flow at constant total gas flows on the chemical, structural and tribo-mechanical properties of the CrAlYN coatings. The nitrogen flow has an important effect on the deposition growth rate, the crystalline structure and the mechanical properties of the CrAlYN coatings. AU the coatings present a NaCl fee lattice structure but increase in the nitrogen flow changes the coating texture. Coatings morphology also changes from a columnar to an equiaxial structure. Coating hardness decreases with increase in the nitrogen flow. AU the coatings studied showed a similar tribological behaviour with a mean friction coefficient against steel between 0.47 and 0.53 without showing a clear correlation with the coatings' mechanical properties.Item Microstructure and wear behavior of DC-pulsed plasma nitrided AISI 316L austenitic stainless steel(2007) De Las Heras, Evangelina; Santamaria, Daniel González; García-Luis, Alberto; Cabo, Amado; Brizuela, Marta; Ybarra, Gabriel; Mingolo, Norma; Brühl, Sonia; Corengia, Pablo; TECNOLOGÍAS DE HIDRÓGENO; INGENIERÍA DE SUPERFICIES; GENERALAustenitic stainless steel are used in industrial applications, mainly due to their good corrosion resistance; however, their low hardness and poor wear performance impose strong limitations in many cases. In this work, the wear behavior of the unnitrided and DC-pulsed plasma nitrided AISI 316L stainless steel has been investigated using an Amsler-Disc-Machine under rolling-sliding contact conditions. The microstructure was studied by X-ray diffraction and the worn surface, subsurface, and wear debris were analyzed by optical microscopy, scanning electron microscopy, and microhardness testing. The obtained results show that pulsed plasma nitriding improves the wear resistance of the AISI 316L and different wear mechanisms were observed depending on the normal applied load.Item Recent advances on membranes and membrane reactors for hydrogen production(2013-04-05) Gallucci, Fausto; Fernandez, Ekain; Corengia, Pablo; van Sint Annaland, Martin; TECNOLOGÍAS DE HIDRÓGENO; GENERALMembranes and membrane reactors for pure hydrogen production are widely investigated not only because of the important application areas of hydrogen, but especially because mechanically and chemically stable membranes with high perm-selectivity towards hydrogen are available and are continuously further improved in terms of stability and hydrogen flux. Membrane reactors are (multiphase) reactors integrating catalytic reactions (generally reforming and water gas shift reactions for hydrogen production) and separation through membranes in a single unit. This combination of process steps results in a high degree of process integration/intensification, with accompanying benefits in terms of increased process or energy efficiencies and reduced reactor or catalyst volume. The aim of this review is to highlight recent advances in hydrogen selective membranes (from palladium-based to silica and proton conductors) along with the advances for the different types of membrane reactors available (from packed bed to fluidized bed, from micro-reactors to bio-membrane reactors). In addition, the application of membrane reactors for hydrogen production from different feedstock is also discussed.Item Surface modification by plasma-based processes(World Scientific Publishing Co., 2009-01-01) De Las Heras, Evangelina; Ybarra, Gabriel; Braceras, Iñigo; Corengia, Pablo; INGENIERÍA DE SUPERFICIES; GENERALIn this chapter, the use of plasma processes technology in the biomedical field is presented. The introduction focuses on plasmas and the associated techniques employed to modify surfaces of a wide variety of materials. The versatility of plasma-based treatments allows the design of special function-oriented surfaces for medical devices, which are presented next. An overview of the plasma-based thin films and surface treatments is included for a number of applications ranging from the improvement of mechanical properties and the modification of the surface chemistry of materials to regulate the interaction with living tissues, diagnostics, and drug delivery.Item Synthesis and characterization of plasma-polymerized HMDSO films using an ion gun inverse magnetron source(2007) García-Luis, Alberto; Corengia, Pablo; González-Santamaría, Daniel; Brizuela, Marta; Braceras, Iñigo; Briz, Nerea; Azpiroz, Patxi; Bellido-González, Victor; Powell, Sarah; TECNOLOGÍAS DE HIDRÓGENO; GENERAL; INGENIERÍA DE SUPERFICIES; SGPlasma-polymerized hexamethyldisiloxane (PPHMDSO) films have been deposited using an ion gun inverse magnetron source at low pressure with Ar/O2/N2/HMDSO plasmas. Deposition rates and structures of the highly cross-linked PPHMDSO layers have been determined. Surface mechanical properties were studied using the nanoindentation technique, and wettability was measured by contact angle method and modifications induced on optical properties were studied at different wavelengths. Results showed remarkable differences in hardness and contact angles of distilled water depending on the plasma conditions. In addition, plasma parameters also had a very significant effect on the background fluorescence.Item Wear behaviour of UHMWPE against DC-pulsed plasma nitrided and duplex treated AISI 316L used in hip joint replacements(2009) Perez, Ezequiel; Pazos, Leonardo; De Heras, Evangelina Las; Parodi, Belén; Corengia, Pablo; Braceras, Iñigo; GENERAL; INGENIERÍA DE SUPERFICIESWear behaviour of the artificial joint replacements plays a critical role in implant failure. The UHMWPE-AISI 316L tribological system, widely used on joint prostheses, was studied. Two surface modifications were applied to the stainless steel counterface: DC-pulsed plasma nitriding and duplex (DC-pulsed plasma nitriding + TiN coating by cathodic-arc evaporation) treatments. An Amsler Disc Machine Type A-135 was used as an approximation to real loading conditions. Worn surfaces, weight loss curves and wear debris were analysed. The results show that the nitriding and duplex treatments improve the wear resistance of the tribological system. Different types of damages were observed on the UHMWPE worn surfaces depending on the surface treatment of the stainless steel.