Sylvain Meille

Institut National des Sciences Appliquées de Lyon | INSA Lyon · Laboratory of Materials: Engineering and Science (MATEIS - UMR 5510)

We have investigated the heating mechanism in industrially relevant, multi-block copolymers filled with Fe nanoparticles and subjected to an oscillatory magnetic field that enables polymer healing in a contactless manner. While this procedure aims to extend the lifetime of a wide range of thermoplastic polymers, repeated or prolonged stimulus heali...

Fracture in nacre-like alumina is studied experimentally and numerically with alumina platelets main alignment direction perpendicular (along-configuration) to the one commonly tested (across-configuration) in the literature. In along-configuration, brittle failure is noted after crack initiation with no macroscopic crack deviation, unlike what is...

The additive manufacturing of composite structures can open possibilities in the design and fabrication of devices but also demands new approaches. In this work, we use thermally reversible pastes to fabricate ceramic matrix (Al2O3) composites reinforced with continuous metallic fibres (steel). The approach is based on the micro-extrusion of cerami...

Indentation-induced cracking with sharp tips is studied on mono- and polycrystalline cubic zirconia. Tests at different applied loads are carried out, ranging below and above a threshold load above which visible surface cracking is noted after testing. This threshold load does not appear to be correlated to any discontinuity in the evolution of eit...

Extensive reliability testing is performed on microelectronic products nowadays to ensure full life cycle operation. Accelerated hydrothermal aging is used to evaluate product sensitivity to the absorption of water and detect any related reliability issue. Sensitivity to accelerated hydrothermal aging (85 °C and 85% relative humidity for 1000 h) is...

Nacre-like aluminas are bio-inspired, ceramic-based composites that display high toughness and strength. Their toughness arises from their brick-and-mortar microstructure. We must understand the role of several microstructural features over their mechanical properties. Techniques that allow microstructural imaging during mechanical tests are theref...

Nacre-like aluminas are bio-inspired, ceramic-based composites that display high toughness and strength. Their toughness arises from their brick-and-mortar microstructure. We must understand the role of several microstructural features over their mechanical properties. Techniques that allow microstructural imaging during mechanical tests are theref...

ConspectusUsing a limited selection of ordinary components and at ambient temperature, nature has managed to produce a wide range of incredibly diverse materials with astonishingly elegant and complex architectures. Probably the most famous example is nacre, or mother-of-pearl, the inner lining of the shells of abalone and certain other mollusks. N...

Gypsum specimen failure under four-point bending is investigated both experimentally and numerically. The analysis accounts for the variation in specimen thickness (in a large range from 10 to 90 mm), in pore volume fraction (related to a variation in elastic and fracture properties) and for the presence of macropores that are likely to trigger fai...

The relevance of the phase-field approach to simulate the fracture in porous ceramics has been investigated. For this purpose, the conditions for the crack initiation using the phase-field model have been compared to the theoretical predictions of the coupled criterion considering a pure V-notch singularity and a crack blunted by a cavity. For two...

To develop durable bone healing strategies through improved control of bone repair, it is of critical importance to understand the mechanisms of bone mechanical integrity when in contact with biomaterials and implants. Bone mechanical integrity is defined here as the adaptation of structural properties of remodeled bone in regard to an applied mech...

Nacre-like alumina is a class of bio-inspired ceramic composite manufactured by field-assisted sintering of green bodies made primarily of alumina platelets with an anisotropic microstructure. Here we investigate the addition of zirconia particles to enhance the mechanical properties of the composite. The resulting structure is a nacre-like anisotr...

Micro-compression tests were carried out on pillars of 60 µm in diameter, milled by plasma focused ion beam in porous Yttria-Stabilized Zirconia (YSZ) pellets. The fracture properties were determined over a wide range of porosities (33%-63%) for 8YSZ and at a given pore volume fraction of 63% for 3YSZ. The mechanical properties determined from test...

This paper is dedicated to the in situ follow up of the setting of an α plaster using synchrotron X-ray tomography, with a high spatial resolution, down to 0.3 µm (0.16 µm voxel size), and a high time resolution with a scan every 30 s. This combination of spatial and time resolution is amongst the best reported in the literature so far and is of pa...

The addition of a ductile phase to a porous ceramic can help overcome the brittleness of ceramics. Yet, most studies so far have focused on the processing and characterization of dense composites. Alternatively, unidirectional pores can improve the strength of porous ceramics. Here we combine the two approaches and show a simple processing strategy...

We evaluate Weibull's approach and the coupled criterion (CC) ability to reproduce bending failure stress variations as a function of specimen size in two porous materials, namely gypsum or zinc oxyde. Whereas both approaches well reproduce the size effect in gypsum specimens, only the CC succeeds in correctly predicting the failure stress variatio...

Poly(L-lactide-co-D,L-lactide) PDLA/45S5 Bioglass® (BG) composites for medical devices were developed using an original approach based on a thermal treatment of BG prior to processing. The aim of the present work is to gain a fundamental understanding of the relationships between the morphology, processing conditions and final properties of these b...

Alkali-activated slag is commonly used as a cement substitute to reduce the environmental footprint of construction materials. Nonetheless, the use of significant amount of alkaline activators, such as sodium silicate or sodium hydroxide, can be detrimental in terms of global warming potential impact. The aim of this work is to use complementary ac...

Two‐photon lithography is a potential route to produce high‐resolution 3D ceramics. However, the large shrinkage due to the elimination of an important organic counterpart of the printed material during debinding/sintering remains a lock to further development of this technology. To limit this phenomenon, an original approach based on a composite r...

Orientation mapping using Electron Back Scattered Diffraction (EBSD) is limited in its spatial resolution by the acceleration voltage, usually higher than 5 kV. In the present work, we present for the first time an orientation mapping at 1 kV obtained by the eCHORD approach (electron CHanneling ORientation Determination) on a lamellar bio-inspired...

Solid Oxide Cell (SOC) is a high-temperature electrochemical device that can be operated in both fuel and electrolysis modes. It is constituted of a dense electrolyte in Yttria Stabilized Zirconia (YSZ) sandwiched between two porous electrodes. The hydrogen electrode is classically made of a cermet composed of Nickel and YSZ (Ni-YSZ). Because of sy...

Nacre-like alumina is a class of bio-inspired ceramic composite manufactured by field-assisted sintering of green bodies made primarily of alumina platelets with an anisotropic microstructure. Here we investigate the addition of zirconia particles to enhance the mechanical properties of the composite. The resulting structure is a nacre- like anisot...

Nacre-like alumina is a class of bio-inspired ceramic composite manufactured by field-assisted sintering of green bodies made primarily of alumina platelets with an anisotropic microstructure. Here we investigate the addition of zirconia particles to enhance the mechanical properties of the composite. The resulting structure is a nacre- like anisot...

Ceramics are brittle, so imagine what porous ceramics are like. This weakness is often a major obstacle in many applications. The addition of a ductile phase such as a polymer to a porous ceramics can help overcome this intrinsic limitation. Yet, most studies so far have focused on the processing and characterization of dense composites, and to som...

Ceramics are brittle, so imagine what porous ceramics are like. This weakness is often a major obstacle in many applications. The addition of a ductile phase such as a polymer to a porous ceramics can help overcome this intrinsic limitation. Yet, most studies so far have focused on the processing and characterization of dense composites, and to som...

A model based on the Phase Field approach has been developed to simulate the local fracture in porous electrode microstructures. The model capacity to predict the crack nucleation and propagation has been studied with theoretical considerations. For the model validation, micro-compression tests have been performed on porous YSZ micro-pillars. As ex...

An alternative to supercritical drying to process silica aerogels is to apply evaporative drying to obtain particles that can then be used in the preparation of composite products. However, the mechanical behaviour of these particles is still poorly understood. In this work, millimetre-sized particles are studied combining experimental testing and...

The failure stress under four-point bending cannot be considered as an intrinsic material property because of the well-known size effect of increasing maximum flexural stress with decreasing specimen size. In this work, four-point bending tests are analyzed with the coupled criterion for different sample sizes. The maximum flexural stress only tend...

Enameloid, the hyper-mineralized tissue covering shark teeth is a complex structure resulting from both ameloblast and odontoblast activity. The way these two types of cells interact to set up this tissue is not fully understood and results in the formation of subunits in the enameloid: the Single Crystallite Enameloid (SCE) and the Bundled Crystal...

A novel hybrid process combining robocasting and starch-consolidation method, enabling the fabrication of ceramic scaffolds with porosity as high as 85%, is developed and applied to the fabrication of zirconia. This process enables a precise control of the volume and size of the porosity. It also allows its hierarchization over 4 decades of length...

Osteomalacia is a pathological bone condition consisting in a deficient primary mineralization of the matrix, leading to an accumulation of osteoid tissue and reduced bone mechanical strength. The amounts, properties and organization of bone constituents at tissue level, are known to influence its mechanical properties. It is then important to inve...

Vickers indentation was used to evaluate the hardness and the apparent fracture toughness of unirradiated and irradiated UO2 fuels, with the objective to determine the effects of the irradiation on mechanical properties. Indentation tests were realized at room temperature on standard and doped UO2 fuels, irradiated in a pressurised water reactor up...

Recently, several types of nacre-like materials have been developed using various methods. However, the resulting materials exhibit a significant randomness and defects compared to natural nacre. Therefore, evaluating the influence of these microstructural variations on the material’s mechanical behavior is of high interest for the development of n...

The use of cement substitute, such as alkali-activated slag, is of great interest in the field of earth-based construction materials to preserve their environmental benefit. Nonetheless, the cationic activity of clayey particles of earth-based materials induces new issues by affecting the alkaline conditions in which slag is activated. This work ai...

The mechanical properties of brick-and-mortar composites depend on their interface fracture properties, which have not been evaluated to date, preventing a rational optimization of the microstructure and of the resulting mechanical properties. Micro-(cantilever) and macro-scale (Single Edge Notched Bending) tests on nacre-like alumina both result i...

Recently, several types of nacre-like materials have been developed using various methods. However, the resulting materials exhibit a significant randomness and defects compared to natural nacre. Therefore, evaluating the influence of these microstructural variations on the material’s mechanical behavior is of high interest for the development of n...

The development of damage-resistant structural materials that can withstand harsh environments is a major issue in materials science and engineering. Bioinspired brick-and-mortar designs have recently demonstrated a range of interesting mechanical properties in proof-of-concept studies. However, reproducibility and scalability issues associated wit...

Bending of micron-scale cantilevers with or without initial notch is simulated by finite element and their fracture is assessed using either the coupled criterion or a cohesive zone model. The fracture toughness and strength of UO2 single grain specimens with several crystal orientations are determined by means of inverse identification based on ex...

Meso-porous γ-alumina ceramics used as catalyst supports are characterized by high porosity fraction (>70%) and specific surface area (>200 m²/g) targeted to ensure high catalytic performances, but at the expense of the mechanical strength. The aim of this work is to link the mechanical properties of three different catalyst supports with their mic...

High strength and high toughness are usually mutually exclusive in materials. Among all material classes, ceramics exhibit a high stiffness and strength, but they present a limited plastic deformation, which results in a moderate toughness. However, tough ceramics have been obtained using anisotropic particles organized in a 'brick and mortar' micr...

For the first time, fracture properties of a UO2 fuel preliminary irradiated in a Pressurized Water Reactor (PWR) were characterized by bending tests. Measurements were made at room temperature and at a local scale on micro-cantilevers. Notched and un-notched specimens were prepared with a Focalized Ion Beam (FIB) microscope. Some cantilevers were...

Bioinspired ceramic-ceramic composites based on alumina platelets with a glassy interphase have recently emerged as a new class of strong and damage-resistant materials. Understanding the fracture properties of nacre-like alumina requires to know the properties of each of its components. However, only the platelets have been individually tested so...

Individual platelets in nacre-like ceramics are able to locally withstand stress levels many times larger than the strength of larger specimens made of the same materials. This size effect, usually reported as being relative to the size of pre-existing defects, is described by considering both stress and energy failure conditions. We show that ther...

div> High strength and high toughness are usually mutually exclusive in materials. Among all material classes, ceramics exhibit a high stiffness and strength, but they present a limited plastic deformation, which results in a moderate toughness. However, tough ceramics have been obtained using anisotropic particles organized in a "brick and morta...

Micro-cantilevers were prepared with a dual beam microscope SEM/FIB on different fresh and irradiated Pressurized Water Reactor (PWR) UO2 fuels. Their fracture properties (fracture toughness and fracture stress) were determined by bending tests, carried out with a nano-indenter in situ of a SEM chamber. Different microstructural features were chara...

div> Among many bioinspired materials contenders, ceramic-ceramic composites based on alumina platelets have recently emerged as a new class of strong and damage-resistant materials. These materials are brick-and-mortar composites, where bricks are single-crystal alumina platelets, and a glassy interphase acts as the mortar. Although several proc...

The objective of this work is to link microstructure features of foamed gypsum (lightweight gypsum board core material) and its compressive properties. Several samples of foamed gypsum with different microstructures were manufactured and characterized by X-ray tomography and 3D image processing. Spherical indentation tests results show that for a s...

This article describes the main experimental methods to determine Young’s modulus and fracture strength of ceramics and glasses. Heterogeneous materials such as concrete, porous or microcracked ceramics, are also considered. The article focuses first on elastic properties determination, using either vibration or direct methods. Then fracture streng...

Objective: To evaluate the effect of artificial aging on the mechanical resistance and micromechanical properties of commercially and noncommercially available zirconia dental implants. Methods: Scanning electron microscopy (SEM) and X-ray computed tomography (X-CT) were performed on implant systems including: Z-systems®, Straumann®, Zibone® and...

Precipitated silica (PS) could be an interesting alternative to fumed silica (FS) for the core of Vacuum Insulation Panels (VIP), in particular to reduce their cost and widen their use. However, compacted PS exhibits, for the same density, lower mechanical properties than FS. A better understanding of the mechanical behavior of these materials woul...

Local fracture toughness of a polycristalline ceramic was characterized with the micro-cantilever bending method. Beams were milled in single grains of cubic zirconia using a Focused Ion Beam (FIB) microscope. Grains with specific crystallographic orientations were chosen using Electron Backscatter Diffraction (EBSD) measurements to test specific p...

Resorbable ceramics used as porous bone substitutes are designed to favor bone in-growth and to be gradually replaced by natural tissues after in vivo resorption. However, a lack of experimental techniques to quantitatively monitor the evolution of their mechanical properties during resorption is noted. In this paper, we propose to use spherical in...

Highly porous silica compacts for superinsulation were characterized by instrumented indentation. Samples showed a multi-scale stacking of silica particles with a total porous fraction of 90 vol %. The two main sources of silica available for the superinsulation market were considered: fumed silica and precipitated silica. The compacts processed wi...

The efficiency of calcium phosphate (CaP) bone substitutes can be improved by tuning their resorption rate. The influence of both crystal orientation and ion doping on resorption is here investigated for beta-tricalcium phosphate (β-TCP). Non-doped and Mg-doped (1 and 6 mol%) sintered β-TCP samples were immersed in acidic solution (pH 4.4) to mimic...

We focus on describing the multi-scale structure of a fumed silica characterized by remarkably low thermal conductivity (ca. 2-5 mW.m-1 .K-1) when used as a core material in vacuum insulating panels. While such powders are known to be highly polydisperse at different lengthscales (hardly quantifiable), we propose to adapt a recent methodology based...

Scaffolds for bone tissue engineering require a combination of bioactivity and bioresorption at the sample surface and high mechanical properties in the bulk. This work presents a novel calcium phosphate (CaP)/polycaprolactone (PCL) scaffold with graded composition and porosity fraction. The scaffold is made of (i) a dense hydroxyapatite (HA)/β-tri...

Conventional composites often do not represent true synergy of their constituent materials. This is particularly evident in biomaterial applications where devices must interact with cells, resist cyclic loads and biodegrade safely. Here we propose a new hybrid system, with co-networks of organic and inorganic components, resulting in unprecedented...

There is a growing interest in the development of composites with complex structures designed to generate enhanced mechanical properties. The challenge is how to implement these structures in practical materials with the required degree of control. Here we show how freeze casting of ceramic preforms combined with metal infiltration can be used to f...

This is a reply to the correspondence of Prof. Robert Ritchie: "On the fracture toughness of bioinspired ceramic materials", submitted to Nature Materials, which discusses the fracture toughness values of the following papers: Bouville, F., Maire, E., Meille, S., Van de Moort\`ele, B., Stevenson, A. J., & Deville, S. (2014). Strong, tough and stiff...

Literature is quite abundant concerning the resorption of calcium phosphates. However, articles on in vitro acellular dissolution tests are scarcer, although these immersion experiments are often considered a first step in establishing a predictive dissolution test and understanding the resorption mechanisms. Also, the comparison of results obtaine...

Although bone formation around and within implants has been intensively studied, the role of pores and pore geometry is still debated. Notwithstanding studies reporting the formation of bone and bone components within pores as small as a few micrometers ('micropores'), bone ingrowth is believed to only occur in pores larger than 100. μm ('macropore...

During the sintering process of ceramic pieces, temperature gradients may arise inside the piece if the thermal cycle is too fast with regards to the size of the ceramic body. Too large temperature gradients may lead to density gradients, thus to strain gradients which may result in defects or in the fracture of the pieces. This article presents bo...

Bone fracture is a major health issue worldwide and consequently there have been extensive investigations into the fracture behavior of human cortical bone. However, the fracture properties of human cortical bone under fall-like loading conditions remains poorly documented. Further, most published research has been performed on femoral diaphyseal b...

The properties of graphene open new opportunities for the fabrication of composites exhibiting unique structural and functional capabilities. However, to achieve this goal we should build materials with carefully designed architectures. Here, we describe the fabrication of ceramic-graphene composites by combining graphene foams with pre-ceramic pol...

Supplementary Figures

An aluminum foam can be characterized by its architecture and by the solid phase’ microstructure. Our aim is to link the foam's morphological and microstructural features with its mechanical properties thanks to X-ray tomography and finite element (FE). An approach combining X-ray tomography at different resolutions, image processing, and FE modeli...

Statement of significance: Ideally, the resorption kinetics of biodegradable bone substitutes should be controlled to favor the healing processes of bone. Although biodegradable bone grafts are already used in surgeries, their resorption process is still partially unknown. The present work studies these resorption phenomena, their kinetics and mec...

Hydroxyapatite (HA)/β-tricalcium phosphate (β-TCP) cellular composites were fabricated by robocasting. Polymeric beads were intentionally added into the solid rods of the samples to generate artificial defects in order to characterize their influence on the fracture behavior in uniaxial compression. The samples were characterized by X-ray tomograph...

Statement of significance: Zirconia-toughened alumina (ZTA) is the current gold standard for the fabrication of orthopedic ceramic components. In the present work, we propose an innovative strategy to provide both osseointegrative and antibacterial properties to ZTA surfaces: we demonstrate that injection molding allows a flexible design of surfac...

Macro-porous β Tricalcium Phosphate (β-TCP) samples were produced by a sacrificial template method with polyethylene (PE) beads used as pore formers. X-ray computed tomography was used at two resolutions to characterize the structure at the scale of the sample and at the scale of the microstructure. For the latter scale, the sample was scanned in a...

This article points out the fact that conventional low temperature silver sintering processes do not seem to satisfy the needs for reliability when they are used to assemble passive components (such as multilayers ceramic capacitors) in electronic modules undergoing wide amplitude thermal cycles (−65°C / +200°C). These processes indeed lead to very...

The first in-situ monitoring of plaster hydration using X-ray tomography is reported in this paper. Dissolution of hemihydrate particles and formation of a network of gypsum needles can be observed in 3D. A 3D quantitative analysis based on the microstructure evolution allows the determination of the degree of reaction. In particular, the size of h...