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J.S. Raminhos, A. Velhinho, Borges J. P. "Development of Polymeric Anepectic Meshes: Auxetic Metamaterials with Negative Thermal Expansion." Smart Materials & Structures. 28 (2019): 045010. Abstract

This paper reports the application of additive manufacturing technology to fabricate bidimensional
lightweight composite meshes capable of demonstrating auxetic properties
(negative Poisson’s ratio (NPR)) in combination with negative thermal expansion (NTE)
behaviour, using as constituent materials polymers that do not exhibit NTE behaviour. To
describe the combination of NPR and NTE characteristics, the designation of ‘anepectic’ is being
proposed. Each mesh, obtained from varying either the material combination or the design
parameters, was tested on a heated silicone bath to study the effects of the different combinations
on the coefficient of thermal expansion (CTE). It was found that all meshes studied demonstrated
a successful combination of NPR and NTE behaviours, and it was revealed that there is a
possibility to tailor the meshes to activate the NTE behaviour within a chosen range of
temperatures. For an extreme case, a Poisson’s ratio of −0.056, along with a CTE of
−1568×10^−6 K−1 has been achieved.

F. Ferreira, I. Ferreira, Camacho Lopes Marques Velhinho E. F. A. A. "Graphene Oxide-Reinforced Aluminium-Matrix Nanostructured Composites Fabricated by Accumulative Roll Bonding." Composites Part B. 164 (2019): 265-271 . Abstract

Accumulative Roll Bonding (ARB) was used to fabricate Graphene Oxide-reinforced Al-matrix composites.
Graphene Oxide reinforcement was suspended in a stabilized aqueous solution and applied, prior to each ARB
cycle, through airgun spraying. Different concentrations (graphene oxide/milipore water) were used and for
each concentration, samples produced have undergone up to 5 rolling cycles.
Optical and electron scanning microscopies were used for microstructural characterization which revealed a
non-homogenous deformation of the layers across the composite's thickness.
Although the presence of graphene-oxide promoted an increase in the microhardness, higher values were
obtained with its lowest concentration for similar samples. The number of ARB cycles and the direction of the
tested sections also influenced the microhardness results since the 5-cycle samples and the rolling direction
sections for all the samples achieved higher hardness results. Graphene Oxide revealed to be a major contributor
to the increase of stiffness during bending of the tested samples.

Carlos F. C. João, Coro Echeverria, Alexandre Velhinho Jorge Carvalho Silva Maria Godinho João Paulo Borges H. "Bio-inspired production of chitosan/chitin films from liquid crystalline suspensions." Carbohydrate Polymers. 155 (2017): 372-381. Abstract

tInspired by chitin based hierarchical structures observed in arthropods exoskeleton, this work reportsthe capturing of chitin nanowhiskers’ chiral nematic order into a chitosan matrix. For this purpose, highlycrystalline chitin nanowhiskers (CTNW) with spindle-like morphology and average aspect ratio of 24.9were produced by acid hydrolysis of chitin. CTNW were uniformly dispersed at different concentrationsin aqueous suspensions. The suspensions liquid crystalline phase domain was determined by rheologicalmeasurements and polarized optical microscopy (POM). Chitosan (CS) was added to the CTNW isotropic,biphasic and anisotropic suspensions and the solvent was evaporated to allow films formation. The Films’morphologies as well as the mechanical properties were explored. A correlation between experimentalresults and a theoretical model, for layered matrix’ structures with fibers acting as a reinforcement agent,was established. The results evidence the existence of two different layered structures, one formed bychitosan layers induced by the presence of chitin and another formed by chitin nanowhiskers layers.By playing on the ratio chitin/chitosan one layered structure or the other can be obtained allowing thetunning of materials’ mechanical properties.

Sá, Sofia, Manoj B. Gawande, Alexandre Velhinho, João Pedro Veiga, Nenad Bundaleski, João Trigueiro, Alexander Tolstogouzov, Orlando M. N. D. Teodoro, Radek Zboril, Rajender S. Varma, and Paula S. Branco. "Magnetically recyclable magnetite-palladium (Nanocat-Fe-Pd) nanocatalyst for the Buchwald-Hartwig reaction." 16 (2014): 3494-3500. Abstract


Savita, Singh, Kale Sandip, Gawande Manoj, Velhinho Alexandre, and Jayarama Radha. "A synthesis of copper based metal-organic framework for O-acetylation of alcohols." 44 (2014): 24-28. Abstract
S.C. Ferreira, A. Conde, Ángeles Arenas Rocha Velhinho M. L. A. A. "Anodization mechanism on SiC nanoparticle reinforced Al matrix composites." Materials. 7 (2014): 8151-8167.
MB, Gawande, Rathi AK, Branco PS, Potewar TM, Velhinho A, Nogueira ID, Tolstogouzov A, Ghumman CAA, and Teodoro OMND. "Nano-MgO-ZrO2 Mixed Metal oxides: Extensive characterization by SIMS and application in the reduction of carbonyl compounds and in multicomponent reactions." 3 (2013): 3611-3617. Abstract
João, Gandra, Vigarinho Pablo, Pereira Diogo, Miranda Rosa, Vilaça Pedro, and Velhinho Alexandre. "Wear characterization of Functionally Graded Surface composites produced by Friction Surfacing." 52 (2013): 373-383. Abstract
MB, Gawande, Velhinho A, Nogueira ID, Ghumman CAA, Teodoro OMND, and Branco PS. "A facile synthesis of cysteine-ferrite magnetic nanoparticles for application in multicomponent reactions-a sustainable protocol." RSC ADVANCES. 2 (2012): 6144-6149. Abstract
João, Gandra, Miranda Rosa M., Vilaça Pedro, and Velhinho Alexandre. "Production of functionally graded surface composites by friction surfacing." Mechanics of Nano, Micro and Macro Composite Structures. 2012. 1-2. Abstract
MB, Gawande, Rathi AK, Branco PS, Nogueira ID, Velhinho A, Shrikhande JJ, Indulkar UU, Jayaram RV, Ghumman CAA, Bundaleski N, and Teodoro OMND. "Regio- and Chemoselective Reduction of Nitroarenes and Carbonyl Compounds over Recyclable Magnetic Ferrite-Nickel Nanoparticles (Fe3O4-Ni) by Using Glycerol as a Hydrogen Source." CHEMISTRY-A EUROPEAN JOURNAL. 18 (2012): 12628-12632. Abstract
J, Gandra, Miranda R, Vilaca P, Velhinho A, and Teixeira JP. "Functionally graded materials produced by friction stir processing." JOURNAL OF MATERIALS PROCESSING TECHNOLOGY. 211 (2011): 1659-1668. Abstract
A, Velhinho, and Rocha LA. "Longitudinal centrifugal casting of metal-matrix functionally graded composites: an assessment of modelling issues." JOURNAL OF MATERIALS SCIENCE. 46 (2011): 3753-3765. Abstract
Ferreira, SC, Velhinho, A, Silva, M. A. G., RJC, Rocha, and LA. "Corrosion behaviour of aluminium syntactic functionally graded composites." Int. J. Mater. & Product Technol.. 39 (2010): 122-135. Abstract


Tiago, Cadavez, Ferreira Sónia, Medeiros Pedro, Quaresma Paulo, Rocha Luís, Velhinho Alexandre, and Vignoles Gérard. "A Graphical Tool for the Tomographic Characterization of Microstructural Features on Metal Matrix Composites." Int. J. of Tomography. & Statistics. 14 (2010): 3-15. Abstract


Botas, JD, Velhinho, A, Silva, M. A. G., and RJC. "A theoretical approach to the elastic behaviour of compact and hollow spherical particles reinforced metal-matrix composites." Int. J. of Mater. Research. 101 (2010): 752-757. Abstract


Paulo, Quaresma, Lopes Adriano, Medeiros Pedro, Preto Bruno, and Velhinho Alexandre. "Tomo-GPU: Um Ambiente de Resolução de Problemas Destinado à Análise de Dados Tomográficos Relativos à Caracterização Estrutural de Materiais." 5 (2010): NONE. Abstract
JD, Botas, Velhinho A, and Silva RJC. "Elastic Behaviour of Spherical Particles Reinforced Metal-Matrix Composites." Advanced Materials Forum Iv. Ed. Baptista APM Sa Alves Malheiros LF Vieira C. F. M. Marques AT, Silva AF. Vol. 587-588. Materials Science Forum, 587-588. 2008. 202-206. Abstract


Velhinho, A., and Ferreira Rocha Vignoles Cloetens S. C. L. A. Braz Fernandes, F.M. "Application of X-ray microtomography to the microstructural characterization of Al-based functionally graded materials." Adv. in Sci. & Technol.. 45 (2006): 1109-1116. Abstract


N, Silva, and Velhinho A. "Assessment of particle clustering in MMCs by quantitative image analysis." Advanced Materials Forum Iii, Pts 1 and 2. Vol. 514-516. Advanced Materials Forum, 514-516. 2006. 779-783. Abstract
A, Velhinho, Vignoles GL, Cloetens P, Thibault X, Boller E, Fernandes FB, Rocha LA, and Botas JD. "Evaluation of SiC-particle connectivity in functionally graded AI/SiCp composites by synchrotron radiation holographic microtomography." FUNCTIONALLY GRADED MATERIALS VIII. 492-493 (2005): 621-626. Abstract
A, Velhinho, Botas JD, Ariza E, Gomes JR, and Rocha LA. "Tribocorrosion studies in centrifugally cast Al-matrix SiCp-reinforced functionally graded composites." Advanced Materials Forum Ii. Vol. 455-456. Materials Science Forum, 455-456. 2004. 871-875. Abstract05_-_mater._sci._forum_455-456_2004_871-875.pdf

The present work reports results obtained from a series of preliminary experiments
aiming at complementing the current knowledge about the wear behaviour of centrifugally-cast
FGM Al/SiCp composites, through concurrent corrosion processes. Precursor MMC’s were
prepared by rheocasting, using 118.8 μm SiC particles and an Al-10Si–2.2 Mg alloy. Those MMC’s
were then molten and centrifugally cast in order to produce cylindrical FGMMC’s. Discs machined
from the top surface of each sample were tested against nodular cast iron pins, using an inverted
configuration pin-on-disc tribometer. Sliding tests took place at room temperature, over a 50000 m
sliding distance, with a sliding speed of 0.3 m s-1, under a 5 N normal load; both dry-sliding and
water-lubricated tests were performed. In order to elucidate the mechanisms involved, the wear
coefficients were calculated for each condition, and the samples were subjected to morphological
characterization via SEM/EDS. Concurrently, in the case of the water-lubrication tests, the
corrosion potential of the tribological pair was monitored. The results obtained show an increase in
material loss for the water-lubricated cases, although variations are registered depending on
reinforcing particle volume fraction. At the same time, the open circuit potential response of the
tribological pair may be correlated with the events of formation/destruction of the tribolayers.

A, Velhinho, Sequeira PD, Fernandes FB, Botas JD, and Rocha LA. "Al/SiCp functionally graded metal-matrix composites produced by centrifugal casting: Effect of particle grain size on reinforcement distribution." Functionally Graded Materials Vii. Vol. 423-4. FUNCTIONALLY GRADED MATERIALS VII, 423-4. 2003. 257-262. Abstract03_-_mater._sci._forum_423-425_2003_257-262.pdf

Functionally graded materials (FGM’s), particularly in the form of Al-Si metal matrix composites (MMC’s) selectively reinforced at the surface with SiC particles, are advanced materials, combining high wear resistance with high bulk toughness or even a thermal barrier at the surface. Centrifugal casting is one of the most effective methods for processing this type of MMC, but accurate control of the ceramic particles distribution/gradient in the metallic matrix has not yet been completely attained. In this work, precursor Al/SiC composites were prepared by rheocasting, using SiC particles and an Al-10Si–2.2 Mg alloy. Morphology of the SiC particles was previously characterized by laser interpherometry and SEM. Differing grain sizes were selected as reinforcing elements. The MMC’s were then molten and centrifugally cast in order to produce the FGM composites, whose structure and properties were investigated by XRD, quantitative image analysis of optical micrographs and longitudinal hardness profiles. Therefore, it was possible to evaluate the influence of the particle grain size on the structure and properties of the FGM. Apart from the evaluation of the effects of particle grain size per se, its influence when combined with differing casting conditions are reported as well.