ISEP - CIDEM - Centro de Investigação em Engenharia Mecânica
URI permanente desta comunidade:
O CIDEM reúne o conjunto de actividade de investigação científica fundamental e aplicada, de desenvolvimento experimental, de formação profissional e de prestação de serviços no âmbito da Engenharia Mecânica.
Objetivos:
Aprofundar os conhecimentos científicos das áreas de investigação fundamental e aplicada;
Criar e apoiar iniciativas conducentes à realização de acções de formação de recursos humanos naqueles domínios;
Difundir o conhecimento científico na sua área de actividade, nomeadamente através da edição de publicações e da realização de encontros, congressos e colóquios nacionais e internacionais;
Promover o intercâmbio científico com instituições e investigadores afins;
Realizar trabalhos de investigação, desenvolvimento e consultoria para o exterior;
Contribuir para o processo de desenvolvimento e modernização do sector produtivo do país na área de Engenharia.
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Percorrer ISEP - CIDEM - Centro de Investigação em Engenharia Mecânica por Domínios Científicos e Tecnológicos (FOS) "Engenharia e Tecnologia::Engenharia Mecânica"
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- Characterization and evaluation of joint properties of friction stir welded AA7075/GNPs joints obtained using square and cylindrical threaded toolsPublication . Fernandes, Filipe; Biradar, Rahul; Patil, Sachinkumar; Nagamadhu, M.; Sharma, PriyaranjanThis study investigates the joint properties and microstructural features of friction stir-welded (FSWed) AA7075 aluminum alloy composites reinforced with 1 wt % of graphene nanoplatelets (GNPs). It focuses on the influence of square (SQ) and cylindrical threaded (CT) tool pin geometries on material flow, GNPs dispersion, and weld quality. The authors conducted comprehensive evaluations using advanced characterization methods including scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and Raman spectroscopy. The results reveal formation of precipitates and well bonding between aluminum alloy and GNPs, resulting in better quality of welds. The SQ tool facilitated superior material stirring and uniform dispersion of GNPs, leading to the formation of fine, equiaxed grains in the nugget zone (NZ). Electron back scatter diffraction (EBSD) analysis presents reduction of grain size of base material from 38 μm to 10 μm in the NZ, significantly enhancing mechanical properties. Welds produced using the SQ tool exhibited higher microhardness (150 HV) and tensile strength (630 MPa) compared to those made with the CT tool (141 HV and 478 MPa), resulting in a 75 % improvement in joint efficiency. Fracture analysis revealed ductile failure in the heat-affected zone (HAZ), with fine dimples observed in SEM images. Additionally, the SQ tool weld demonstrated a lower wear rate, reduced from 70 μm to 25 μm, than its counterpart. These findings highlight the importance of tool geometry in producing defect-free, high-performance welds.
- Design of DC semi-industrial magnetron-sputtered W-Ti-N/Ag composite films: Insights into the microstructure and mechanical propertiesPublication . Fernandes, Filipe; Luan, Jing; Wang, Yiping; Dong, Songtao; Evaristo, Manuel; Cavaleiro, Albano; Ju, HongboA semi-industrial magnetron sputtering system was employed to deposit a series of W-Ti-N/Ag composite films with varying Ag content, aiming to provide practical parameters for industrial-scale PVD applications. The films were deposited by DC sputtering a W + 30 wt%Ti alloy target and an Ag target in an Ar and N2 atmosphere. The results indicated that the composite films, regardless of Ag content, exhibited a face-centered cubic (fcc) structure and consisted of a three-phase mixture of W2N, TiN and Ag. The Ag particles were embedded within the crystalline grains of solid solution of (WTi)2N and (TiW)N, resulting in grain refinement and increased interface density in the films. The predominant cross-section fracture of the Ag-alloyed was identified as transgranular. Both hardness and elastic modulus of the composite films gradually decreased with the Ag content due to the soft nature of the Ag phase.
- Improvement of Surface Properties and Wear Resistance of Selective Laser Melting-Fabricated Inconel 625 Alloy by Ultrasonic Nanocrystal Surface Modification for Demanding ApplicationsPublication . Fernandes, Filipe; Fathipour, Zahra; Hadi, Morteza; Bayat, Omidnconel 625 alloy is widely utilized in the production of components for demanding industries. This study investigates the effect of ultrasonic nanocrystal surface modification (UNSM) on the surface properties and wear resistance of Inconel 625 alloy produced by selective laser melting (SLM). Specifically, it focused on analyzing the effect of UNSM on the microstructure, hardness, surface roughness, coefficient of friction and essentially wear resistance of the alloy. The results showed that the microstructure formed by SLM, characterized by relatively large melt pools, was modified by UNSM to a depth of approximately 10 to 15 microns, resulting in a new microstructure composed of deformed grains without changing the chemical composition. Surface hardness increased by over 63% after UNSM treatment. In addition, the surface roughness initially induced by the SLM process was reduced by more than 90%, resulting in a tenfold reduction in the coefficient of friction. Wear path analysis showed that while the abrasive wear mechanism of the alloy remained unchanged, the UNSM treated samples exhibited increased debris production and more frequent delamination due to reduced workability. The alterations in surface properties, including reduced crystallite size, increased lattice strain, grain refinement, and decreased surface area, have been identified as key contributors to the enhanced hardness and wear resistance of the alloy following UNSM treatment.
- Machinability and surface integrity analysis of Ti-17 alloy using WEDC for advanced aero-engine applicationPublication . Fernandes, Filipe; Chinna, Ramatenki; Sharma, PriyaranjanRecent advancements in aerospace industry demand intricate aero-engine parts, leading to the increased use of titanium alloys, particularly Ti-17, due to its high strength, thermal stability, and corrosion resistance. However, its low thermal conductivity and tool wear tendency pose significant machining challenges, impacting surface integrity, fatigue life, and overall component performance. This study investigates the Wire Electrical Discharge Cutting (WEDC) process, revealing that the mechanism behind improved surface integrity lies in the controlled thermal input, which minimizes phase transformations and reduces residual stresses. Experimental results reveal that rough-cutting Ti-17 yields higher surface roughness of ∼2.68 μm than that of finish cutting of ∼1.01 μm, with increased microhardness up to 80 μm depth. Further, rough cutting leads to a thicker recast layer of ∼10–15 μm, and higher residual stresses of ∼540 MPa, while finish cutting achieves a thinner recast layer of ∼2–5 μm and reduced stresses of ∼304 MPa. The innovation of this study is the investigation of WEDC behavior in Ti-17 alloy, addressing a gap in understanding its surface integrity features to improve the performance, durability, and service life of aero-engine components, advancing next-generation aerospace manufacturing.
- Mutually enhanced mechanical and tribological properties in magnetron sputtered Mo2N/Ag-SiNx self-lubricating multilayered films via epitaxial growth designPublication . Fernandes, Filipe; Luan, Jing; Wang, Lei; Dong, Songtao; Choukourov, Andrei; Yang, Junfeng; Kalin, Mitjan; Cavaleiro, Albano; Ju, Hongbo; Vincenzini, P.Achieving simultaneous enhancement of both mechanical and self-lubricating properties by incorporating soft lubricants into nitride films has been a longstanding challenge in the development of solid lubricant materials. This paper introduced a novel approach to overcome this challenge by developing coherent-structured Mo2N/Ag-SiNx multilayered films using radio frequency (RF) magnetron sputtering. The multilayer films were designed with a fixed modulation period of 30 nm, while the modulation ratio (γ) was varied from 1:9 to 1:1. The Mo2N layers exhibited a single fcc-Mo2N phase, while the Ag-SiNx layers formed a dual-phase structure comprising fcc-Ag nanoparticles embedded in an amorphous SiNx matrix. At a modulation ratio of 1:9, the Ag-SiNx layer epitaxially grew on the Mo2N template, resulting in a coherent structure. This coherent structure significantly enhanced both the hardness and elastic modulus, reaching approximately 36 GPa and 230 GPa, respectively. The improved wear resistance at room temperature can be attributed to the coherent strengthening effect, which not only elevated the film's hardness but also eliminated sharp interfaces between modulation layers, thereby reducing crack initiation sites. In temperature-cycling tribo-testing from room temperature to 600 °C, the film with a γ of 1:9 maintained a stable coefficient of friction around 0.2, except during the initial room temperature, where it was 0.4. The wear rate could not be accurately calculated due to the adhered tribolayer on the top of the wear track following the initial tribo-test at 600 °C. The excellent tribological properties across temperature cycles were attributed to the synergistic lubricant characteristics of both layers and the formation of self-lubricating tribo-phases. The optimized Mo2N/Ag-SiNx multilayered films provide an effective balance of lubrication and mechanical stability under extreme conditions, making them highly promising for high-performance engineering applications.
- Nitrogen alloyed MoSe2 coatings – Role of optimized morphology, structure and mechanical properties on diverse environment sliding performancePublication . Fernandes, Filipe; Yaqub, Talha Bin; Nadeem, Irfan; Yaqoob, Khurram; Kalin, Mitjan; Cavaleiro, AlbanoTransition metal dichalcogenide (TMD) coatings are gaining increasing interest among the scientific community as eco-friendly solutions for reducing friction, improving energy conservation, and lowering carbon footprints. N-alloyed MoSe2 coatings (MoSeN), a subset of TMDs, remain largely underexplored, with no research on their frictional performance across various sliding environments. Herein, an in-depth analysis of DC-magnetron sputtered MoSeN coatings is presented, with N content varying from 0 to 42 at%. Investigation of composition, morphological features, crystal structure, mechanical strength and sliding performance are accessed. Our findings revealed that N additions resulted in increased compactness, amorphous structure and hardness of ∼4.6 GPa, and these improvements remained consistent despite compositional variations. The sliding competency was evaluated under six different conditions, revealing promising results in ambient-air and dry-N2 atmospheres at room conditions and 100 °C. At 200 °C, the sliding performance in ambient-air was better than dry-N2. Friction coefficient for N-alloyed coatings was relatively close, ranging between 0.03 and 0.06, except for a dry-N2 environment at 200 °C. Nevertheless, wear rate showed slight variations, with higher values observed in dry-N2 at 100 °C and 200 °C but remained within a specific range of 1–7 × 10−7 mm3/Nm for all other conditions. This study highlights the potential of MoSeN coatings to be scaled for industrial applications, offering a roadmap for reducing the inherent limitations of PVD sputtering.
- Performance analysis of steel W18CR4V grinding using RSM, DNN-GA, KNN, LM, DT, SVM models, and optimization via desirability function and MOGWOPublication . Fernandes, Filipe; Touati, Sofiane; Boumediri, Haithem; Karmi, Yacine; Chitour, Mourad; Boumediri, Khaled; Zemmouri, Amina; Moussa, AthmaniThis study presents an innovative approach to optimizing the grinding process of W18CR4V steel, a high-performance material used in reamer manufacturing, using advanced machine learning models and multi-objective optimization techniques. The novel combination of Deep Neural Networks with Genetic Algorithm (DNN-GA), K-Nearest Neighbors (KNN), Levenberg-Marquardt (LM), Decision Trees (DT), and Support Vector Machines (SVM) was employed to predict key process outcomes, such as surface roughness (Ra), maximum roughness height (Rz), and production time. The results reveal significant improvements, with Ra values ranging from 0.231 μm to 1.250 μm (up to 81.5 % reduction) and Rz from 1.519 μm to 6.833 μm (up to 77.7 % reduction). The hybrid DNN-GA model achieved R2 > 0.99, reducing prediction errors by 23–45 % compared to traditional models. Optimization via the Desirability Function achieved Ra values around 0.341 μm and Rz around 2.3 μm, with production times ranging from 1181 to 1426 s. The innovative Multi-Objective Grey Wolf Optimization (MOGWO) provided Pareto-optimal solutions, minimizing Ra to 0.3 μm, Rz to 1.5 μm, and production times between 2000 and 3000 s, offering better balance between surface quality and machining efficiency. This work highlights the unique integration of machine learning models with optimization techniques to significantly enhance grinding performance and manufacturing efficiency in high-precision industries.
- Performance evaluation of CrAlNAg-coated inserts with varying Ag content during roughing and finishing operations in face millingPublication . Fernandes, Filipe; Rajput, Sumit Singh; Upadhyay, Chandramani; Gangopadhyay, SoumyaThe performance of a novel hard solid lubricant coating, CrAlNAg, in the face milling operation of AISI 1045 medium carbon steel under the modes of roughing and finishing was investigated. Dry machining was carried out using CrAlN coated inserts with varying silver (Ag) contents ranging from 0 to 16 at.%. The objective was to evaluate the performance of the developed coatings under different machining conditions, which could potentially result in (a) a high material removal rate (rough machining) and (b) high surface finish and dimensional accuracy (finish machining). An in-depth analysis of the cutting forces in face milling was performed to assess the impact of the coatings under these machining conditions. During machining, the force components in the X, Y, and Z directions were measured using a cutting force dynamometer attached to the workpiece. The components of these forces concerning the tool edge were calculated using geometrical characteristics and mathematical formulations, enabling the identification of the true cutting forces and the most sensitive force components relative to the cutting parameters. Apart from cutting forces, chip temperature, tool wear, surface roughness, and chip characteristics were evaluated for different coating compositions under both machining conditions. Owing to superior coating-substrate adhesion and tribological characteristics, the CrAlNAg9 coating with around 8.6 at.% of Ag was found to significantly reduce dominant forces and chip temperature under both machining conditions. Furthermore, the same coating exhibited remarkable resistance to flank wear compared to other compositions of CrAlNAg coatings.
- Tribological performance of different alloyed DLC and AlTiSiN coatings when sliding against Inconel 718 alloy for demanding applicationsPublication . Fernandes, Filipe; Pérez-Salinas, Cristian; Evaristo, Manuel; Cavaleiro, Albano; Kumar, Ch. Sateesh; Lacalle, L. Norberto López; Rios, P.Machining Ni alloys such as Inconel 718 is challenging due to its good mechanical properties, low thermal conductivity and low elastic modulus, which causes high cutting temperatures at the chip-tool interface. The use of self-lubricating coatings, such as DLCs coatings has potential to improve significantly the machinability of Ni alloys. This research work aims to explore how different DLC, DLC-Si, DLC-W coatings behave tribologically when sliding against Inconel 718. The results will be compared with an industrial AlTiSiN coating used to protect the cutting tools. The morphology, mechanical properties and chemical composition of the coatings were analysed. To evaluate the tribological behaviour alternative sliding tests were performed under different conditions (room temperature – RT and 200 °C in dry condition and at RT with lubrication, using CUT-MAX S 50259-1 oil. The DLC coatings showed remarkable self-lubricating efficiency, with low coefficients of friction even in dry conditions, demonstrating that their self-lubricating capability is effective without the need for external lubricants. However, at a temperature of 200 °C, a significant increase in wear rate was observed for all DLC coatings, being 3 to 4 times higher as compared to that at room temperature. This is mainly caused by the conversion of sp3 to sp2 bonds coating oxidation. On the other hand, AlTiSiN demonstrated consistent specific wear rate, despite of the unfavourable circumstances, highlighting its suitability to use in extreme environments. These results show the limitations in film performance and underline the importance of balancing the strength of the coating with its impact on the opposing surface. Furthermore, it highlights the need to improve the thermal stability of DLC coatings for application in high temperature environments and dry conditions.
- Zirconium aluminum nitride thin films for temperature sensing applicationsPublication . Fernandes, Filipe; Martins, Bruno; Patacas, Carlos; Cavaleiro, Albano; Faia, Pedro; Alves, Cristiana F. Almeida; Carbo-Argibay, Enrique; Ferreira, Paulo J.This study explores the development and characterization of zirconium aluminum nitride (ZrAlN) thin films produced via magnetron sputtering for temperature sensing applications. The sensor film is integrated into a fully nitride multilayer coating and designed to work in harsh environments. The ZrAlN demonstrated stable semiconductor behavior up to 750 °C, making it suitable for high-temperature thermistors, with a β value of approximately 850 K after signal stabilization. Detailed structural characterization confirmed a mixed-phase structure of poorly crystalline cubic ZrN and orthorhombic Zr3N4. This structure is believed to be responsible for the high resistivity of 8.0 × 105 µΩ·cm observed in Zr1-xAlxN with x = 0.3. The examination of Zr0.7Al0.3N integrated into the multilayer coating revealed a columnar morphology with diffuse nanolayers, alternating between aluminum-rich and aluminum-poor zones, caused by the two-fold rotational deposition. The sensor coating was further tested on a cutting tool substrate, with the Zr0.7Al0.3N layer exhibiting a sensitivity of 800 K and demonstrating effective temperature measurements up to 400 °C. The Zr0.7Al0.3N layer inserted in a nitride-based multilayer coating, combined with Arduino® for signal acquisition, resulted in a measured error of approximately 7 %. The setup presented the potential for integration into manufacturing environments aligned with Industry 4.0.