arXiv subjects

Hortense Le Ferrand

Publications and source records attributed to Hortense Le Ferrand.

16 recordsLinked to original sources

arXiv2025

Assessing prompting frameworks for enhancing literature reviews among university students using ChatGPT

Writing literature reviews is a common component of university curricula, yet it often poses challenges for students. Since generative artificial intelligence (GenAI) tools have been made publicly accessible, students have been employing them for their academic writing tasks. However, there is limited evidence of structured training on how to effectively use these GenAI tools to support students in writing literature reviews. In this study, we explore how university students use one of the most popular GenAI tools, ChatGPT, to write literature reviews and how prompting frameworks can enhance their output. To this aim, prompts and literature reviews written by a group of university students were collected before and after they had been introduced to three prompting frameworks, namely CO-STAR, POSE, and Sandwich. The results indicate that after being exposed to these prompting frameworks, the students demonstrated improved prompting behaviour, resulting in more effective prompts and higher quality literature reviews. However, it was also found that the students did not fully utilise all the elements in the prompting frameworks, and aspects such as originality, critical analysis, and depth in their reviews remain areas for improvement. The study, therefore, raises important questions about the significance of utilising prompting frameworks in their entirety to maximise the quality of outcomes, as well as the extent of prior writing experience students should have before leveraging GenAI in the process of writing literature reviews. These findings are of interest for educators considering the integration of GenAI into academic writing tasks such as literature reviews or evaluating whether to permit students to use these tools.

cs.CY↗

arXiv2024

Ultrafast high-temperature sintering of dense and textured alumina

Crystallographic texture engineering in ceramics is essential to achieve direction-specific properties. Current texture engineering methods are time-consuming, energy extensive, or can lead to unnecessary diffusion of added dopants. Herein, we explore ultrafast high-temperature sintering (UHS) to prepare dense and textured alumina using templated grain growth (TGG). From a slurry containing alumina microplatelets coated with Fe3O4 nanoparticles dispersed in a matrix of alumina nanoparticles, green bodies with oriented microplatelets were prepared using magnetic assisted slip casting (MASC). The effects of the sintering temperature, time and heating rate on the density and microstructure of the obtained ceramics were then studied. We found that TGG occurs for a temperature range between 1640 and 1780 °C and 10 s sintering time. Sintering at 1700 °C for 10 s led to dense and textured alumina with anisotropic grains thanks to the Fe3O4 coating, which did not have the time to diffuse. The highest texture and relative density were obtained with a heating rate of ~5,500 °C/min, leading to texture-dependent anisotropic mechanical properties. This study opens new avenues for fabricating textured ceramics in ultra-short times.

cond-mat.mtrl-sci↗

arXiv2024

Effect of interfacial Fe3O4 nanoparticles on the microstructure and mechanical properties of textured alumina densified by ultrafast high-temperature sintering

Alumina microplatelets coated with a small amount of Fe3O4 can be oriented via a rotating magnetic field to create texture. After ultrafast high-temperature sintering (UHS), Fe atoms are found at the grain boundaries and within the grains, influencing the mechanical properties. Here, we compare the microstructure and mechanical properties of textured alumina prepared with and without Fe3O4 and sintered using UHS or conventional sintering (CS). Microstructural analysis using electron backscattering diffraction (EBSD) indicates that Fe3O4 induces crystallographic defects in the ceramic after UHS. Nanoindentation measurements enlighten that the presence of Fe3O4 leads to plastic flow that increases the energy dissipation, reaching ~122 % at a maximum load of 1900 mN compared to pristine samples. Overall, due to the concentrated effects of Fe3O4 after UHS, the flexural strength and fracture toughness values are higher than the other two samples, reaching values of ~287 MPa and 7 MPa.m0.5, respectively. These results could be leveraged to produce stronger and tougher ceramics.

cond-mat.mtrl-sci↗

arXiv2022

Energy dissipation in composites with hybrid nacre-like helicoidal microstructures

Natural ceramic composites present complex microstructures that lead to tortuous crack paths and confer them high toughness. Current microreinforced composites do not yet reach the same level of complexity in their microstructures, resulting in poorer properties. To achieve complex microstructuration, magnetically-assisted slip casting (MASC) was conducted using a setup with 4 degrees of freedom. Among all possible microstructures, a hybrid design between nacre-like and helicoidal arrangements was selected due to its ability to tilt and twist the crack path. The hybrid microstructured specimen fabricated, consisting of aluminum oxide micro platelets in a silicone matrix, were tested under compression and their mechanical performance compared. Although nacre-like composites exhibited the highest strength and toughness, helicoidal hybrids could show some ductility and higher stiffness. The fabrication strategy proposed here could thus be a simple route to study more complex microstructures in view of increasing the toughness of microplatelet reinforced composites.

cond-mat.mtrl-sci↗

arXiv2021

Magnetically driven in-plane modulation of the 3D orientation of vertical ferromagnetic flakes

External magnetic fields are known to attract and orient magnetically responsive colloidal particles. In the case of 2D microplatelets, rotating magnetic fields are typically used to orient them parallel to each other in a brick-and-mortar fashion. Thanks to this microstructure, the resulting composites achieve enhanced mechanical and functional properties. However, parts with complex geometry require their microstructure to be specifically tuned and controlled locally in 3D. Although the tunability of the microstructure along the vertical direction has already been demonstrated using magnetic orientation combined with sequential or continuous casting, controlling the particle orientation in the horizontal plane in a fast and effective fashion remains challenging. Here, we propose to use rotating magnetic arrays to control the in-plane orientation of ferromagnetic Nickel flakes distributed in uncured polymeric matrices. We experimentally studied the orientation of the flakes in response to magnets rotating at various frequencies and precessing angles. Then, we used COMSOL to model the magnetic field from rotating magnetic arrays and predicted the resulting in-plane orientations. To validate the approach, we created composites with locally oriented flakes. This work could initiate reverse-engineering methods to design the microstructure in composite materials with intricate geometrical shapes for structural or functional applications.

cond-mat.soft↗

arXiv2021

Assessment of nacre-like ceramics in replacement to Ni superalloys in aircraft's engines

Aviation's fossil fuel emissions contribute to global warming. The production and disposal of the materials used in aircrafts too. The current metallic alloys present in the hot section of engines pose constraints in terms of temperature, pressure and weight that restrain the performance of the aircrafts. Also, these alloys are produced using rare, depleting resources, and polluting processes. In this paper, we hypothesize the use of bioinspired nacre-like alumina (NLA), a ceramic material that exhibits unusual toughness, and evaluate its potential as a replacement for superalloys in aircraft's engines. Comparing the performance of Ni superalloys and NLA in terms of properties, engine performance, and life cycle sustainability, we find NLA a promising alternative although progress has to be made with regards to its reliability, shaping, repair, and governance of the production process.

physics.app-ph↗

arXiv2021

Programmable multistability for 3D printed reinforced multifunctional composites with reversible shape change

4D printing empowers 3D printed structures made of hydrogels, liquid crystals or shape memory polymers, with reversible morphing capabilities in response to an external stimulus. To apply reversible shape-change to stiff lightweight materials such as microfiber reinforced polymers, we developed a composite ink that can be printed using direct-ink-writing (DIW), and that exhibits multistability around its glass transition temperature. After curing at room temperature, the flat print thermally morphs into a predefined shape upon heating at an actuation temperature and cooling down. The sample can then reversibly snap between multiple stable shapes when heated above its glass transition temperature thanks to prestress-induced multistability. The key that allows thermal morphing and prestress multistability is the microstructuring of the 3D printed composites by shear-induced alignment of reinforcing microfibers. This alignment leads to local anisotropy in thermomechanical properties and the build-up of prestresses. Furthermore, the ink composition can be tuned to generate shape-dependant reversible functional properties, such as electrical conductivity. Based on finite element modelling and experimental results, the method proposed here can be used for variety of compositions and designs, for applications where stiffness, reconfigurability and shape-dependent functionalities can be exploited.

physics.app-ph↗

arXiv2021

A materials perspective on the design of damage-resilient artificial bones and bone implants through additive/advanced manufacturing

After more than five decades of research, the failure of bone implants is still an issue that becomes increasingly urgent to solve in our ageing population. Among the reasons for failure, catastrophic brittle fracture is one event that is directly related to the implant s material and fabrication and that deserves more attention. Indeed, clinically available implants pale at reproducing the hierarchical and heterogeneous microstructural organization of our natural bones, ultimately failing at reproducing their mechanical strength and toughness. Nevertheless, the recent advances in additive and advanced manufacturing open new horizons for the fabrication of biomimetic bone implants, challenging at the same time their characterization, testing and modelling. This critical review covers selected recent achievements in bone implant research from a materials standpoint and aims at deciphering some of the most urgent issues in this multidisciplinary field.

cond-mat.mtrl-sci↗

arXiv2021

Magnetic slip casting: a review of current achievements and issues

Ceramic materials are ubiquitous in technologies operating under high mechanical, thermal or chemical constrains. Research in ceramic processing aims at creating ceramics with properties that are still challenging to obtain, such as toughness, transparency, conductivity, among others. Magnetic slip casting is a ceramic process where an external magnetic field is used to align the ceramic grains along preferential crystallographic directions, thereby creating controlled texture. Over the past 20 years of research on magnetic slip casting, ceramics of multiple chemistry were found to exhibit enhanced properties as a result from the texturation. This paper reviews the progress in the field of magnetic slip casting, details the processing parameters, the textures obtained for a diverse range of ceramic materials. The achieved mechanical and functional properties of the magnetically textured parts are presented. This overview of the magnetic slip casting process allows to identify critical directions for future advancement in advanced technical ceramics

cond-mat.mtrl-sci↗

arXiv2021

Porous textured ceramics with controlled grain size and orientation

Texture in dense or porous ceramics can enhance their functional and structural properties. Current methods for texturation employ anisotropic particles as starting powders and processes that drive their orientation into specific directions. Using ultra-low magnetic fields combined with slip casting, it is possible to purposely orient magnetically responsive particles in any direction. When those particles are suspended with nanoparticles, templated grain growth occurs during sintering to yield a textured ceramic. Yet, the final grains are usually micrometric, leading weak mechanical properties. Here, we explore how to tune the grain orientation size using magnetic slip casting and templated grain growth. Our strategy consists in changing the size of the anisotropic powders and ensuring that magnetic alignment and densification occurs. The obtained ceramics featured a large range of grain anisotropy, with submicrometric thickness and anisotropic properties. Textured ceramics with tunable grains dimensions and porosity are promising for filtering, biomedical or composite applications.

cond-mat.mtrl-sci↗

arXiv2021

Bioinspired approaches to toughen calcium phosphate-based ceramics for bone repair

To respond to the increasing need for bone repair strategies, various types of biomaterials have been developed. Among those, calcium phosphate ceramics (CPCs) are promising since they possess a chemical composition similar to that of bones. To be suitable for implants, CPCs need to fulfill a number of biological and mechanical requirements. Fatigue resistance and toughness are two key mechanical properties that are still challenging to obtain in CPCs. This paper thus reviews and discusses current progress in the processing of CPCs with bioinspired microstructures for load-bearing applications. First, methods to obtain CPCs with bioinspired structure at individual lengthscales, namely nano-, micro-, and macroscale are discussed. Then, approaches to attain synergetic contribution of all lengthscales through a complex and biomimetic hierarchical structure are reviewed. The processing methods and their design capabilities are presented and the mechanical properties of the materials they can produce are analysed. Their limitations and challenges are finally discussed to suggest new directions for the fabrication of biomimetic bone implants with satisfactory properties. The paper could help biomedical researchers, materials scientists and engineers to join forces to create the next generation of bone implants.

cond-mat.mtrl-sci↗

arXiv2019

Modeling the effect of microstructure on elastic wave propagation in platelet-reinforced composites and ceramics

Dense ceramics are irreplaceable in applications requiring high mechanical stiffness, chemical and temperature resistance and low weight. To improve their toughness, ceramics can be reinforced with elongated inclusions. Recent manufacturing strategies have been developed to control the orientations of disc-like micro-particles in polymeric and ceramic matrices and to build periodic microstructures. Given the infinite number of possible microstructures available, modeling tools are required to select the potentially best design. Periodic microstructures can be involved in elastic wave scattering to dissipate mechanical energy from vibrations. In this paper, a model is proposed to determine the frequency bandgaps associated to periodic architectures in composites and ceramics and the influence of microstructural parameters are investigated. The results are used to define guidelines for the future fabrication of hard bulk ceramic materials that combine traditional ceramic properties with high vibration resistance.

physics.app-ph↗

arXiv2019

Robotics: Science preceding science fiction

Robots and artificial machines have been captivating the public for centuries, depicted first as threats to humanity, then as subordinates and helpers. In the last decade, the booming exposure of humans to robots has fostered an increasing interest in soft robotics. By empowering robots with new physical properties, autonomous actuation, and sensing mechanisms, soft robots are making increasing impacts on areas such as health and medicine. At the same time, the public sympathy to robots is increasing. However, there is still a great need for innovation to push robotics towards more diverse applications. To overcome the major limitation of soft robots, which lies in their softness, strategies are being explored to combine the capabilities of soft robots with the performance of hard metallic ones by using composite materials in their structures. After reviewing the major specificities of hard and soft robots, paths to improve actuation speed, stress generation, self-sensing and actuation will be proposed. Innovations in controlling systems, modeling, and simulation that will be required to use composite materials in robotics will be discussed. Finally, based on recently developed examples, the elements needed to progress toward a new form of artificial life will be described.

physics.app-ph↗

arXiv2018

Design principles for textured multi-layered composites using magnetically assisted slip casting

In many natural multi-layered composites, such as in the dactyl club of Stomatopods or the shell of bivalve mollusks, the defining functional and structural properties are determined by locally varying orientations of inorganic building blocks within each layer. One approach to artificially produce textured microstructures inspired by such complex composites is magnetically assisted slip-casting (MASC). MASC is a colloidal process in which anisotropic particles are oriented at arbitrarily defined angles using a magnetic field. The orientation of the particles is maintained during growth as particles are collected from the wall of a porous mold. Whereas a number of proof-of-concept studies have established the potential of the technique, the full design space available for MASC-fabricated structures, and the limits of the approach, have so far not been explored in a systematic manner. To fill this gap, we have studied both theoretically and experimentally the various torques that act on the particles at different stage of the assembly process. We define the boundary conditions of the MASC process for magnetically responsive alumina platelets suspended in a low-viscosity aqueous suspension, considering the composition of the colloidal suspension and the dynamics of the particle-alignment process under a rotating magnetic field. Taken together, these findings define a design strategy for the fabrication of designed multi-lamellar microstructures using MASC. Our guidelines are based on a comprehensive understanding of the physical mechanisms governing the orientation and assembly of anisotropic particles during MASC and indicate a route to expanding this technique to building blocks of various chemistries, and thus to broadening the range of bio-inspired composites with customized multi-scale structures that can be produced for specific applications.

cond-mat.soft↗

arXiv2018

Processing of dense bio-inspired ceramics with deliberate microtexture

The architectures of biological hard materials reveal finely tailored complex assemblies of mineral crystals. Numerous recent studies associate the design of these local assemblies with impressive macroscopic response. Reproducing such exquisite control in technical ceramics conflicts with commonly used processing methods. Here, we circumvent this issue by combining the recently developed Magnetically-Assisted Slip Casting (MASC) technique with the well-established process of Templated Grain Growth (TGG). MASC enables the local control over the orientation of platelets dispersed among smaller isotropic particles. After a high temperature pressure-less treatment, the grains of the final ceramic follow the same orientation of the initial platelets. This combination allows us to produce 95 % dense alumina part with a grain orientation following any deliberate orientation. We successfully fabricated microstructures inspired from biological materials with ceramics that present periodically varying patterns with a programmable pitch of a few tens of microns. We confirmed the capacity of the process to tailor local mechanical properties through local grains orientation using micro-indentation. This micrometer scale control over the local mechanical properties could be applied to adapt ceramic structures to complex loads using this inexpensive and scalable process. In systems where functional properties also depend on anisotropic grain orientation, the principle presented here could enable the creation of new multifunctional ceramics.

cond-mat.mtrl-sci↗

arXiv2016

Magnetically-Assisted Slip Casting of Bioinspired Heterogeneous Composites

Composites are often made heterogeneous in nature to fulfill the functional demands imposed by the environment, but remain difficult to fabricate synthetically due to the lack of adequate and easily accessible processing tools. We report on an additive manufacturing platform to fabricate complex-shaped parts exhibiting bio-inspired heterogeneous microstructures with locally tunable texture, composition and properties and unprecedentedly high volume fractions of inorganic phase (up to 100%). The technology combines an aqueous-based slip casting process with magnetically-directed particle assembly to create programmed microstructural designs using anisotropic stiff platelets in a ceramic, metal or polymer functional matrix. Using quantitative tools to control the casting kinetics and the temporal pattern of the applied magnetic fields, we demonstrate that this robust approach can be exploited to design and fabricate heterogeneous composites with thus far inaccessible microstructures. Proof-of-concept examples include bulk composites with periodic patterns of micro-reinforcement orientation and tooth-like bilayer parts with intricate shapes displaying site-specific composition and texture.

cond-mat.mtrl-sci↗