Browsing by Author "De Heras, Evangelina Las"
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Item Mechanical properties of layers obtained by DC-pulsed plasma nitriding on a low-alloy steel (AISI 4140)(2009) Dutrey, Luciano; De Heras, Evangelina Las; Svoboda, Hernán G.; Corengia, Pablo A.; GENERALAn industrial DC-pulsed plasma nitriding (DCPPN) equipment was used to obtain samples of an AISI 4140 low-alloy steel with five different configurations: substrate, substrate + diffusion zone, diffusion zone, substrate + diffusion zone + compound layer, and diffusion zone + compound layer. The microstructures of the samples were investigated by scanning electron microscopy and X-ray diffraction. Microhardness and tensile tests were performed, and the fracture mechanisms for the different materials were finally analyzed and discussed. The DCPPN produced an increase in the elastic modulus as well as in the yield strengths, together with a pronounce ductility loss, associated to the brittle intergranular fracture surface due to the nitride precipitation in the grain boundaries.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.