Percorrer por autor "Ferreira, Fábio"
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- An algorithm of a costing system for electroplatingPublication . Pires, António; Ferreira, Fábio; Ávila, Paulo; Mota, AlziraBusinesses are increasingly competitive and rigorous and it is essential the existence of a strong, effective and realistic costing system. Decisions taken on the basis of the costing are very important, they can make the difference between success and failure of the organization. This paper explains the construction of an initial algorithm that aims to calculate the costs associated with electroplating of metal articles, in a specific company. This work can act as a possible guide for the construction of the costing system algorithms in this type of industry.
- Influence of 1-Ethyl-3-methylimidazolium Diethylphosphate Ionic Liquid on the Performance of Eu- and Gd-Doped Diamond-like Carbon CoatingsPublication . Sadeghi, Mohammadamin; Omiya, Takeru; Fernandes, Filipe; Vilhena, Luís; Ramalho, Amílcar; Ferreira, FábioA composite lubricating system that combines solid and liquid lubrication can create a synergistic effect by leveraging the strengths of both types of lubricants. Solid lubrication coatings possess advantageous load-bearing abilities and exhibit low volatility. By adopting this approach, the system retains the merits of solid lubrication while simultaneously harnessing the advantages of liquid lubrication. The unique properties of diamond-like carbon coatings (DLCs) offer the potential to create binding locations for lubricant additives by introducing dopant elements that have a high affinity with additives. In the present work, the combined use of europium-doped diamond-like carbon (Eu-doped DLC) with varying atomic concentrations of the dopant element (1.7 at. % and 2.4 at. %) and gadolinium-doped diamond-like carbon (Gd-doped DLC) with different atomic concentrations of the dopant element (1.7 at. % and 2.3 at. %) was studied alongside a pure DLC coating and the incorporation of an ionic liquid (IL) additive in a tribological block-on-ring system. The focus was on the 1-Ethyl-3-methylimidazolium diethylphosphate ionic liquid with a concentration of 1 wt. % in polyalphaolefin (PAO) 8. Among the investigated pairs, the coefficient of friction (CoF) of 1.7 at. % Eu-doped DLC coupled with the IL was the smallest in boundary, mixed, and elastohydrodynamic lubrication regimes. Quantification of wear was challenging due to minimal and localized wear on the DLC coating surfaces. The decrease in friction within the boundary lubrication regime underscores the promise of mechanical systems that integrate 1.7 atomic percent Europium-doped diamond-like carbon coatings with ionic liquids (IL). This study presents a compelling avenue for future scholarly exploration and research efforts focused on reducing friction and improving the efficiency of moving components, particularly in situations where tribological properties exert a substantial influence
- Microstructure, Mechanical, and Tribological Properties of Mo2N/Ag-SiNx Nanomultilayers with Varying Modulation PeriodsPublication . Fernandes, Filipe; Luan, Jing; Wang, Lei; Dong, Songtao; Ferreira, Fábio; Mo, Changpan; Cavaleiro, Albano; Ju, Hongbo; Kiryukhantsev-Korneev, PhilippThe multilayered Mo2N/Ag-SiNx self-lubricant films were designed and deposited using a DC (Direct Current) magnetron sputtering system under mixed gas atmosphere of N2 and Ar. The modulation ratio (thickness ratio of Mo2N to Ag-SiNx) was fixed at 2:1, while the modulation periods (thickness of Mo2N and its adjacent Ag-SiNx layer) were set at 20, 40, and 60 nm. The results indicated that all multilayer films, regardless of modulation period, exhibited a combination of face-centered cubic (fcc) and amorphous phases. Specifically, fcc-Mo2N was detected in the Mo2N layers, while fcc-Ag and amorphous SiNx co-existed in the Ag-SiNx layers. The multilayered architecture induced residual stress and interface strengthening, resulting in hardness values exceeding 21 GPa for all films. Compared to Mo2N and Ag-SiNx monolayer films, the multilayer structure significantly enhanced tribological properties at room temperature, particularly in terms of wear resistance. The Mo2N/Ag-SiNx multilayer films exhibit ~25% lower friction than Ag-SiNx, ~3% lower than Mo2N, and achieve remarkable wear rate reductions of ~71% and ~85% compared to Ag-SiNx and Mo2N, respectively, demonstrating superior tribological performance. The synergistic effects of both modulation layers and relative high hardness were key factors contributing to the enhanced tribological behavior.
- Structural, mechanical and tribological properties of WCTiN coatings produced by HiPIMSPublication . Sanches, José; Ferreira, Fábio; Fernandes, Filipe; Cavaleiro, Albano; Serra, RicardoWear can be decreased by applying protective multi-element thin films on the surface of mechanical components (e.g., cutting tools and brake discs). The current study examines how substrate polarisation voltage affects the structural-mechanical relationships of WTiCN thin films made using a combination of HiPIMS and DCMS reactive sputtering. A chemical and structural study of the coatings conducted using EDS and XRD reveals the development of a composite phase structure. Additionally, the microstructure and morphology of the coating, as revealed by SEM and AFM, shows that defect-free surfaces are possible to obtain. Then, sliding (scratch and pin-on-disk) and indentation (nano-indentation) tests are used to examine the films’ mechanical characteristics (hardness, adhesion, friction coefficient and wear rate). It shows that substrate polarisation voltage of −60 V must be used to generate surfaces that are resistant to wear. The reason for this is the ideal levels of tungsten concentration (19 at.%), root mean square surface roughness (4.5 nm) and hardness (29 GPa) have been reached.
- Tribological Behavior of Doped DLC Coatings in the Presence of Ionic Liquid Additive under Different Lubrication RegimesPublication . Sadeghi, Mohammadamin; Omiya, Takeru; Fernandes, Filipe; Vilhena, Luís; Ramalho, Amilcar; Ferreira, FábioDiamond-like carbon (DLC) coatings are widely used in industries that require high durability and wear resistance, and low friction. The unique characteristics of DLC coatings allow for the possibility of creating adsorption sites for lubricant additives through the doping process. In this study, the combined use of europium-doped diamond-like carbon (Eu-DLC), gadolinium-doped diamond-like carbon (Gd-DLC), and pure DLC coatings and an ionic liquid (IL) additive, namely, trihexyltetradecylphosphonium bis (2-ethylhexyl) phosphate [P66614] [DEHP], with a 1 wt.% concentration in polyalphaolefin (PAO) 8 as a base lubricant was investigated. Higher hardness, higher thin-film adhesion, a higher ratio of hardness to elastic modulus, and a higher plastic deformation resistance factor were achieved with the Gd-DLC coating. The CoF of the Gd-DLC coating paired with the IL was superior compared to the other pairs in all lubrication regimes, and the pure DLC coating had a better performance than the Eu-DLC coating. The wear could not be quantified due to the low wear on the surface of the DLC coatings. The friction reduction demonstrates that tribological systems combining Gd-DLC thin films with an IL can be a potential candidate for future research and development efforts to reduce friction and increase the efficiency of moving parts in internal combustion engines, for instance.