Browsing by Keyword "Electrical contact resistance"
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Item Electrical contact resistance and tribological behaviors of self-lubricated dielectric coating under different conditions(2020-03) Echeverrigaray, F.G.; de Mello, S.R.S.; Leidens, L.M.; Boeira, C.D.; Michels, A.F.; Braceras, I.; Figueroa, C.A.; INGENIERÍA DE SUPERFICIESIn this study, the electro-tribological performance of hydrogenated amorphous carbon coatings against bearing steel in different experimental conditions was continuously monitored by means of coefficient of friction (CoF) and electrical contact resistance (ECR). The influence of tribosystem variables such as humidity, velocity and lifetime on frictional and electrical response were also compared with specific wear energy calculation method. The main findings of both tribological and electrical behaviors include the dissipated energy and the micro-slip dielectric failures that can be linked to the properties of self-lubricating layers, which depend also on the working media. In this framework, the electro-tribological evaluation provides an electrical monitoring tool for coating premature wear detection in real time.Item Nitriding of titanium by hollow cathode assisted active screen plasma and its electro-tribological properties(2021-04-15) Domínguez-Meister, Santiago; Ibáñez, Iñigo; Dianova, Anastasia; Brizuela, Marta; Braceras, Iñigo; Tecnalia Research & Innovation; INGENIERÍA DE SUPERFICIESTitanium presents good corrosion resistance, a high strength-to-weight ratio, but poor tribological properties. However, these can be enhanced by nitriding processes. Hollow cathode assisted active screen plasma has proved to be an effective and fast nitriding technique. In this work, the effect of process parameters (hollow cathode induced temperature and plasma intensity, electrical bias…) on the resulting surface microstructure (XRD, SEM/EDS), finishing and hardness of titanium (TiGr4) have been studied. Additionally, the electro-tribological properties have been evaluated on a ball on cylinder reciprocating configuration. The results show that hollow cathode assisted active screen plasma nitriding of titanium can produce titanium nitride surfaces with thicknesses far exceeding those typical in PVD coatings. Moreover, higher plasma processing intensities can generate same layer thicknesses at lower temperatures, minimizing the deleterious effect on grain size growth. Finally, monitoring of the electrical contact resistance can provide valuable information concerning the evolution of the status of the surfaces.Item TiN-Ag as an antimicrobial and wear resistant coating(2021-12) Braceras, Iñigo; Brizuela, Marta; Álvarez, Noelia; Martínez Van Geeteruyen, Miguel; Azkona, Ibon; INGENIERÍA DE SUPERFICIES; BiomaterialesNosocomial infections are a major clinical concern, posing great risks for patients and rising costs for health services providers. This work aims at developing a hard, wear resistant coating, whose antimicrobial properties shall prevent the transmission of infections. TiN coatings deposited by Physical Vapour Deposition, PVD, with different Ag contents have been studied, especially in relation to the hardness and adhesion, their microstructure and morphology. The antimicrobial activity of the surfaces has been assessed against Staphylococcus epidermidis at different time frames, one of the most troublesome source of infections in trauma and orthopaedic surgeries. The electro-tribology properties of different silver contest have been studied. Finally, the coatings have been deposited on surgical acetabular reamers and wear resistance tests have been carried out against synthetic composite bone (simulating cortical and cancellous bone). Results have shown a good coating adhesion on stainless steel (both quantitatively in the scratch tests and qualitatively in the tests against synthetic composite bone), while the hardness decreased with higher Ag percentages. Furthermore, coatings exhibited antimicrobial activity against S.epidermidis, limited silver release, a remarkable wear resistance (vs. uncoated surgical acetabular reamers), while the electrical contact resistance provided valuable information about the evolution of friction and the status of the coating. Therefore TiN-Ag coatings present promising features for reducing the risk of infections, monitoring and extending cutting edge life and quality, and thus limiting damage to living tissues, e.g. necrosis.