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479 results on '"Cavaleiro, Albano"'

2. A deep learning approach to the texture optimization problem for friction control in lubricated contacts

Author

Silva, Alexandre, Lenzi, Veniero, Pyrlin, Sergey, Carvalho, Sandra, Cavaleiro, Albano, and Marques, Luís

Subjects
Physics - Computational Physics, Physics - Applied Physics
Abstract

The possibility to control friction through surface micro texturing could offer invaluable advantages in many fields, from wear and pollution reduction in the transportation industry to improved adhesion and grip. Unfortunately, the texture optimization problem is very hard to solve using traditional experimental and numerical methods, due to the complexity of the texture configuration space. In this work, we apply machine learning techniques to perform the texture optimization, by training a deep neural network to predict, with extremely high accuracy and speed, the Stribeck curve of a textured surface in lubricated contact. The deep neural network was used to completely resolve the mapping between textures and Stribeck curves, enabling a simple method to solve the texture optimization problem. This work demonstrates the potential of machine learning techniques in texture optimization for friction control in lubricated contacts.

Published
2022

30. Tribological Comparison of Coatings Produced by PVD Sputtering for Application on Combustion Piston Rings.

Author

Ferreira, Ney Francisco, Fernandes, Filipe, Neis, Patric Daniel, Poletto, Jean Carlos, Yaqub, Talha Bin, Cavaleiro, Albano, Vilhena, Luis, and Ramalho, Amilcar

Subjects
PISTON rings, BOUNDARY lubrication, DRY friction, DOPING agents (Chemistry), ENERGY consumption, DIAMOND-like carbon
Abstract

This article compares the tribological performance of coatings produced by PVD sputtering. Transition metal dichalcogenide (TMD) coatings doped with carbon (WSC and MoSeC) and nitrogen (WSN and MoSeN) and a conventional diamond-like carbon (DLC) coating are compared. The tribological evaluation was oriented towards the use of coatings on piston rings. Block-on-ring tests in a condition lubricated with an additive-free polyalphaolefin (PAO 8) and at temperatures of 30, 60, and 100 °C were carried out to evaluate the coatings in boundary lubrication conditions. A load scanner test was used to evaluate dry friction and scuffing propensity. In addition to WSN, all other TMD coatings (WSC, MoSeC, and MoSeN) exhibited lower friction than DLC in dry and lubricated conditions. The study reveals that WSC, among TMD coatings, offers promising results, with significantly lower friction levels than DLC, while demonstrating reduced wear and a lower risk of metal adhesion. These findings suggest that WSC may be a viable alternative to DLC in piston rings, with potential benefits for reducing fuel consumption and increasing engine durability. [ABSTRACT FROM AUTHOR]

Published
2024
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34. Phase tailoring of tantalum thin films deposited in deep oscillation magnetron sputtering mode

Author

Ferreira, Fábio, Sousa, Cláudio, Cavaleiro, Albano, Anders, André, and Oliveira, João

Subjects
Ta films, DOMS, HiPIMS, Film growth, Phase tailoring, Condensed Matter Physics, Physical Chemistry (incl. Structural), Materials Engineering, Applied Physics
Abstract

The effect of energetic ion bombardment on the properties of tantalum thin films was investigated. To achieve such energetic ion bombardment during the process the Ta thin films were deposited by deep oscillation magnetron sputtering (DOMS), an ionized physical vapor deposition technique related to high power impulse magnetron sputtering. The peak power was between 49 and 130 kW and the substrate was silicon at room temperature and ground potential. The directionality and the energy of the depositing species was controlled by changing the ionization fraction of the Ta species arriving at the substrate at different peak powers. In this work, the surface morphology (AFM), microstructure (SEM), structure (XRD) and hardness and Young's modulus (nanoindentation) of the films were characterized. The ion energy distributions (IEDs) were measured using an electrostatic quadrupole ion energy and mass spectrometer (HIDEN EQP 300). The IEDs showed that the DOMS process applies a very energetic (up to 120 eV) ion bombardment on the growing tantalum films. Therefore, with such conditions it was possible to deposit pure α-Ta (of 2 μm of thickness) without the use of additional equipment, i.e., without substrate bias or substrate heating. Conditions are therefore significantly different than in previous works, offering a much simpler and cheaper solution to up-scale for industrial operation.

Published
2017

39. The Green Lubricant Coatings Deposited by Physical Vapor Deposition for Demanding Tribological Applications: A Review.

Author

Kong, Fanlin, Luan, Jing, Xie, Fuxiang, Zhang, Zhijie, Evaristo, Manuel, and Cavaleiro, Albano

Subjects
TRANSITION metal nitrides, PHYSICAL vapor deposition, DIAMOND-like carbon, SUSTAINABLE design, SURFACE coatings
Abstract

The emergence of nanotechnology and surface engineering techniques provides new opportunities for designing self-lubricant coatings with enhanced properties. In recent years, green coating technologies have played a vital role in environmental preservation. This article mainly reviews five typical types of self-lubricant coatings including MoN coatings, VN coatings, WN coatings and TMN (Transition Metal Nitride) soft-metal coatings, and DLC (Diamond-like Carbon) with lubricant agents deposited by PVD (Physical Vapor Deposition) for the demanding tribological applications, which is the latest research into the green lubricant coatings. Furthermore, it is of great significance for designing the green self-lubricant coatings to adapt the demanding tribological applications to meet the industrial requirements. [ABSTRACT FROM AUTHOR]

Published
2024
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