One of the main problems in ships is corrosion, which reduces the lifetime usage of ship parts and increases maintenance costs. Ceramic coatings can contribute to solving this situation. Zirconium nitrides obtained by reactive unbalanced magnetron sputtering technology are largely reported as coatings with high corrosion resistance. The present study used high-power impulse magnetron sputtering in a reactive atmosphere (R-HiPIMS), varying the nitrogen amount. SEM, EDS, XRD, AFM, and contact angle measurements were used to assess the obtained coatings’ performance. Corrosion resistance was evaluated using electrochemical impedance spectroscopy (EIS) (up to 168 h exposure) and potentiodynamic polarization (PP) in NaCl (3.5% wt.—“artificial seawater”) solution. According to the results, cross section micrographs showed strong densification of ZrN films regardless of the nitrogen amount. Besides, nitrogen increases during deposition influenced the drop of applied peak power (Pp) to the target and, consequently, influenced other film properties, such as roughness, wettability, and corrosion resistance. PP and EIS tests demonstrate the protective behavior of films under artificial seawater exposure. The results prove that the implementation of HiPIMS technology to obtain ZrN films could contribute to increasing the corrosion resistance of coated ship metallic parts and, hence, help maritime transportation to reduce maintenance time and cost.
We aim at developing hexavalent chromium-free coatings for frequently touched decorative parts. Cr(N,O) and multilayered CrN/CrO coatings were deposited by means of reactive magnetron sputtering. All samples presented good adhesion to the substrates enhanced by an epoxy layer designed to enhance PVD coating adhesion. Similar substrates are found in the automotive industry and can be used in appliances where a metallic finish is desired by the consumer. Corrosion behavior was induced, using artificial sweat to simulate long exposure to human touch for 96 h. In potentiodynamic polarization tests, the coatings were revealed to be nobler than the substrate alone. Cr displayed a non-existent passivation region, while gCrN exhibited a quick passivation of the surface and its respective breakdown and several current fluctuations, indicating the occurrence of pitting, which was confirmed by SEM micrography after the corrosion. Regarding EIS results, all films depicted a diminution of impedance modulus (|Z|) after 96 h, which indicates a diminution of corrosion resistance against artificial sweat. Nitride films exhibited the worst anticorrosive features. On the other hand, Cr and CrO exhibited the highest |Z| values. These results are corroborated by low the corrosion rates of both coatings. The equivalent electrical circuit allows us to confirm oxide formation in the outermost layer of the films due to electrolyte/surface interaction, indicating a self-protecting mechanism. Nitride films showed the lowest values and less corrosion resistance, confirming the results obtained in polarization potentiodynamic tests. The coatings developed in this work, namely Cr and CrO, showed a promising corrosion resistance behavior that could endure a lifetime of frequent human touch in various decorative applications either automotive or general appliances.
This study investigates the properties of LiCoO2 coatings as cathodes for lithium-ion batteries, focusing on the effects of annealing on their structural, morphological, chemical, vibrational, and electrochemical characteristics. The LiCoO2 coatings were deposited on silicon and glass substrates using RF magnetron sputtering at 100 W and subsequently annealed at 600 °C for 1 h. The films were characterized before and after annealing using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and electrochemical impedance spectroscopy (EIS). Annealing improved the crystallinity of LiCoO2, which is critical for enhancing lithium-ion diffusion. Furthermore, an XPS analysis revealed a layered structure with a Li-rich outer layer and a Co-rich underlayer, indicating a more uniform distribution of Li and Co, along with increased oxygen content. Additionally, the annealing process refined the microstructure of the LiCoO2 coating, positively impacting its electrochemical performance. A comparative analysis of cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) results demonstrated a significant improvement in the charge/discharge capacity post-annealing. This study successfully highlights the beneficial effects of annealing on LiCoO2 thin-film cathodes, offering valuable insights for developing more efficient and sustainable lithium-ion batteries through sputter-deposition processes.
En este artículo, se presenta una revisión bibliográfca acerca de la implementación delanálisis de causa raíz (RCA, por sus siglas en inglés) a diversos problemas presentados en elementosmecánicos en diversas industrias del sector productivo. Se hace una breve contextualización sobrequé es el RCA y los pasos que se deben realizar para poder efectuarlo de una manera correcta en unproblema ingenieril y su utilidad en cuanto a la mitigación de gastos, en una obra, en una planta, o encualquier otra situación que merezca realizar una investigación de esta naturaleza. Las investigaciones mostradas en este artículo exponen diferentes casos que aplican la metodología RCA para determinar la causa de falla de piezas críticas dentro de diversos equipos. El común de estas indagacionesmuestra unos pasos que son imprescindibles, como explicar la naturaleza del elemento de falla, desarrollar una caracterización fsicoquímica del material del elemento mediante técnicas de espectroscopia, micrografía, fractografía y, en algunos casos, aplicación de los conceptos de diseño medianteel análisis por elementos fnitos. Además, se hace una comparación del elemento de estudio coninvestigaciones recientes o previas sobre mecanismos de falla posible a fn de determinar la posiblecausa raíz de falla del elemento estudiado. En algunos casos, los autores dan recomendaciones parala mitigación de los riesgos de falla, que llevan consigo un mejoramiento operativo y económico.