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- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- Modelo rigoroso de selecção de sistemas de recursos para o projecto de empresas ágeis/virtuais para produtos complexosPublication . Ávila, PauloA emergência de novos requisitos para os sistemas de produção tem despoletado desafios no desenvolvimento de projectos de novos modelos organizacionais, nomeadamente do tipo Ágil/Virtual. Integrada num desses projectos, designado por “BM_Virtual Enterprise Architecture Reference Model” (BM_VEARM), esta tese pretende contribuir para a resolução do problema de selecção de recursos quer para esse mesmo projecto, quer para outros que se debatam com o mesmo tipo de problema. Definimos os objectivos deste trabalho de doutoramento em: Mostrar as limitações dos modelos de selecção existentes por forma a potenciar a construção dum novo modelo; Construir um modelo de selecção de sistemas de recursos rigoroso e abrangente a qualquer método de selecção associado a qualquer dimensão do plano de tarefas e dos seus requisitos associados; Validar a necessidade dum Broker para efectuar a selecção do sistema de recursos, com base no modelo desenvolvido e simultaneamente validar o próprio modelo. Resumidamente, pretendemos mostrar que o processo de selecção seguindo um modelo de selecção abrangente a qualquer requisito de selecção tem maior domínio de validação se for efectuado por um Broker, e desta forma validar o projecto do processo de selecção da BM_VEARM.Para realizar o trabalho e podermos alcançar os objectivos a que nos propusemos, organizou-se a tese da seguinte forma: decorrente da análise do estado da arte que fizemos, mostramos que os objectivos do trabalho se enquadravam nas necessidades de investigação; Criámos um modelo de selecção rigoroso e abrangente, constituído pelas actividades mais representativas dum processo de selecção, tendo-se introduzido pela primeira vez actividades que até ao momento nunca haviam sido ponderadas, como a avaliação do espaço de soluções e a selecção do algoritmo de selecção; construiu-se um demonstrador numérico para o modelo de selecção baseado em estimativas reais dos seus parâmetros e com base no nosso conhecimento, que permitiu simular o desempenho do Broker e do Principal com esse modelo. Com as simulações do demonstrador e seus resultados, validámos: 1. A necessidade do Broker no processo de selecção tal como defendíamos em tese para o nosso modelo BM_VEARM, sendo extensível a outros modelos de Empresas Ágeis / Virtuais. Mostrámos que a importância do Broker é tanto maior quanto maior o número de tarefas, o número de recursos pré-seleccionados e quanto mais complexo for o método de selecção. 2. O nosso modelo de selecção no sentido de que pode ser aplicado a qualquer método de selecção para qualquer dimensão do plano de tarefas, mas que, para que possa ser abrangente necessita dum Broker munido com as ferramentas apropriadas para a selecção.
- Exploring the user-generated content data to improve quality managementPublication . Maia, Sara; Domingues, José Pedro Teixeira; Varela, Maria Leonilde R. Rocha; Fonseca, Luís MiguelThe focus of this research is to investigate if user-generated content (UGC) generated in the Booking platformcan support qualitymanagement improvement within the hospitality industry by increasing customer satisfaction and eliminating defects more efficiently. Hence, it contributes to understanding how data-driven companies can rely on customer data to focus on innovation and performance improvement to meet customer requirements, eliminate defects and increase customer satisfaction.
- Manufacturing companies Industry 4.0 maturity level: A multivariate analysisPublication . Fonseca, Luís Miguel Ciravegna Martins da; Pereira, Teresa; Oliveira, Marisa; Ferreira, Fernanda; Busu, MihailThis research investigates Portuguese manufacturing companies’ Industry 4.0 (I4.0) maturity perception level and proposes an index to measure that aim. The research results show that the most critical factors in evaluating the perception level of I4.0 Perception Maturity (IPM) are strategy, leadership, and customer experiences. The result for the Global Index was 53.50%. Hence, the global Index companies’ perception of the level of maturity of I4.0 in Portugal is medium.