Publications scientifiques incluant nos produits

Nanodispersions zilight From Mathym

3 May 2024

Conventional sintering of nano-crystalline Yttria-Stabilized Zirconia enables high-strength, highly translucent and opalescent dental ceramics

Omid Akhlaghi, Erik Camposilvan, Vincent Garnier, Zahra Goharibajestani, Sirous Khabbaz, Cleva Ow-Yang, Yves Jorand, Laurent Gremillard, Jérôme chevalier

INSA Lyon, 69621 Villeurbanne, France

Development of restorative materials capable of mimicking optical and mechanical performance of natural teeth is a quest in aesthetic density. Yttria-Stabilized Zirconia (YSZ) ceramics represent one of the most popular choices for dental restorations, owing to their biocompatibility, white colour, and the possibility to use CAD-CAM technologies. In particular, YSZ doped with 3 mol. % yttria (3YSZ) is popular because it presents high strength. Nonetheless, the limited light transmission of commercially available high strength 3YSZ does not meet the requirements of highly aesthetic cases. On the other side, YSZ presenting a larger portion of yttria are more translucent but exhibit modest strength. Here, we report on fabrication of dense zirconia nanostructures in bulk form via conventional pressure-less sintering at temperatures down to 1100–1200 ◦C, achieving highly translucent and strong 3YSZ with significant opalescent behaviour. Both Hall− Petch and inverse Hall-Petch relationship were observed in 3YSZ samples with average grain size in the range of 250 nm and 55 nm, demonstrating the importance of grain size control to enhance both optical and mechanical properties of zirconia ceramics, simultaneously. Maximum biaxial strength of 1980 ± 260 MPa, in-line light transmission of 38% in the visible spectrum and opalescence approaching that of enamel were obtained at optimum grain size of 80 ± 5 nm. The notable optical properties are linked to the miniaturization of the residual pores and refinement of grain size towards the nanoscale while the superior mechanical strength is justified by the activation of different energy dissipation processes at nano and macroscale

Alumine ultra-pure CR30F

2022

Iron encapsulated carbon nanotube composites embedded in alumina with enhanced magnetic properties

Steven Rhodes a, Warner Cribb b, Valentin Taufour c, Dwight Patterson d, Dereje Seifu e, Saeed Kamali a,f,*, Suman Neupane

USA

Alumina serves as a vital ceramic insulator, complemented by the intriguing properties of carbon nanotubes (CNTs), including mechanical, thermal, electrical, and magnetic traits. This study was conducted on the creation of CNTs/Al2O3 nanocomposites via the chemical vapor deposition (CVD) process using iron as a catalyst. Various techniques such as transmission electron microscopy, scanning electron microscopy, X-ray diffractometry, thermogravimetric analysis, and Mössbauer spectroscopy were utilized to examine the composite's structure and appearance. The experimental findings reveal uniform distribution of CNTs with an average diameter of 40 nm within the alumina matrix, constituting 7% of the composite. Vibrating sample magnetization measurements exhibit a significant enhancement in ferromagnetic properties for CNT/Al2O3 nanocomposites compared to Fe-catalyzed Al2O3. The saturation magnetization of CNT/Al2O3 is 1.78 e.m.u./g, marking an impressive 5800% increase from the 0.03 e.m.u./g observed for Fe-catalyzed Al2O3 at an applied field of 1.5 T. Moreover, the coercivity of CNTs/Al2O3 composites rises from 0.036 T at 300 K to 0.285 T at 5 K. This study introduces a straightforward method to amalgamate magnetic properties with potential thermoelectric materials.

Spinelle S25

2020

Sustainable acrolein production from bio-alcohols on spinel catalysts: Influence of magnesium substitution by various transition metals (Fe, Zn, Co, Cu, Mn)

Vincent Folliarda, Georgeta Postolea, Livia Marrab, Jean-Luc Duboisc, Aline Auroux

France

Acrolein is a widely used intermediate of synthesis for value-added compounds in a number of domains of application. This work reports on the sustainable synthesis of acrolein by oxidative coupling of bio-alcohols, which constitutes a very promising alternative to fossil fuel-based production. The synthesis is performed in two sequential reactors, using an iron molybdate catalyst for oxidation and then a magnesium aluminate spinel where magnesium is partly or totally substituted by transition metals (Fe, Zn, Co, Cu, Mn) as a catalyst for crossaldolization. The acid-base properties of the latter catalysts were determined using SO2 and NH3 adsorption microcalorimetry. Adsorption microcalorimetry was also used to study the adsorption properties of the reactants, with formaldehyde, acetaldehyde and propionaldehyde as probe molecules, and was complemented by a FT-IR investigation of reactant adsorption in order to better understand the mechanisms of adsorption and reaction. Acrolein production was found to be correlated to the ionic radius of the transition metals used in the catalysts, indicating that electronic effects are likely a factor influencing the acrolein production.

Spinelle S25

2020

Oxidative coupling of a mixture of bio-alcohols to produce a more sustainable acrolein: An in depth look in the mechanism implying aldehydes co-adsorption and acid/base sites

Vincent Folliarda, Georgeta Postolea, Jean-François Devauxb, Jean-Luc Duboisc, Livia Marrad, Aline Aurouxa,*

France

The industrial synthesis of acrolein is mainly performed by propylene oxidation over bismuth-iron-molybdate catalysts. Among cleaner alternatives to produce acrolein, oxidative coupling of methanol and ethanol represents a promising way. In this work, the reaction has been performed in two separate reactors (for oxidation and aldolization) to study the role of the acid/base properties but also the competition of aldehydes adsorption over environmentally friendly spinel catalysts with various Al/Mg ratios. The acid/base properties of catalysts were investigated by NH3 and SO2 adsorption microcalorimetry. Further adsorption microcalorimetry studies were performed with methanol, formaldehyde, acetaldehyde and propionaldehyde to investigate the bounding properties of the reactants. The acid/base properties were correlated with acrolein yield and selectivity under oxidizing conditions. Co-adsorption of aldehydes was also investigated allowing justification of the absence of crotonaldehyde formation.

Spinelle spinel S30CR

March 2021

3D Printing of Transparent Spinel Ceramics with Transmittance Approaching the Theoretical Limit

H. Wang

Singapore

3D printing of transparent ceramics has attracted great attention recently but faces the challenges of low transparency and low printing resolution. Herein, magnesium aluminate spinel transparent ceramics with transmittance reaching 97% of the theoretical limit are successfully fabricated using a stereolithography-based 3D printing method assisted by hot isostatic pressing and the critical factors governing the transparency are revealed. Various transparent spinel lenses and microlattices are printed at a high resolution of ≈100-200 µm. The 3D printed spinel lens demonstrates fairly good optical imaging ability, and the printed spinel diamond microlattices as a transparent photocatalyst support for TiO2 significantly enhance its photocatalytic efficiency compared with its opaque counterparts. Compared with other 3D printed transparent materials such as silica glass or organic polymers, the printed spinel ceramics have the advantages of broad optical window, high hardness, excellent high-temperature stability, and chemical resistance and therefore, have great potential to be used in various optical lenses/windows and photocatalyst supports for application in harsh environments.

Alumine ultra-pure CR6 Baikalox®

15 June 2023

A Combined Gas and Water Permeances Method for Revealing the Deposition Morphology of GO Grafting on Ceramic Membranes

Evdokia Galata, Charitomeni M. Veziri, George V. Theodorakopoulos, ORCID,George Em, Romanos, Evangelia A. Pavlatou

Athens

The adhesion enhancement of a graphene oxide (GO) layer on porous ceramic substrates is a crucial step towards developing a high-performance membrane for many applications. In this work, we have achieved the chemical anchoring of GO layers on custom-made macroporous disks, fabricated in the lab by pressing α-Al2O3 powder. To this end, three different linkers, polydopamine (PDA), 3-Glycidoxypropyltrimethoxysilane (GPTMS) and (3-Aminopropyl) triethoxysilane (APTMS), were elaborated for their capacity to tightly bind the GO laminate on the ceramic membrane surface. The same procedure was replicated on cylindrical porous commercial ZrO2 substrates because of their potentiality for applications on a large scale. The gas permeance properties of the membranes were studied using helium at 25 °C as a probe molecule and further scrutinized in conjunction with water permeance results. Measurements with helium at 25 °C were chosen to avoid gas adsorption and surface diffusion mechanisms. This approach allowed us to draw conclusions on the deposition morphology of the GO sheets on the ceramic support, the mode of chemical bonding with the linker and the stability of the deposited GO laminate. Specifically, considering that He permeance is mostly affected by the pore structural characteristics, an estimation was initially made of the relative change in the pore size of the developed membranes compared to the bare substrate. This was achieved by interpreting the results via the Knudsen equation, which describes the gas permeance as being analogous to the third power of the pore radius. Subsequently, the calculated relative change in the pore size was inserted into the Hagen–Poiseuille equation to predict the respective water permeance ratio of the GO membranes to the bare substrate. The reason that the experimental water permeance values may deviate from the predicted ones is related to the different surface chemistry, i.e., the hydrophilicity or hydrophobicity that the composite membranes acquire after the chemical modification. Various characterization techniques were applied to study the morphological and physicochemical properties of the materials, like FESEM, XRD, DLS and Contact Angle.

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Alumine ultra-pure CR6 Baikalox®

November 2022

Composite GO/Ceramic Membranes Prepared via Chemical Attachment: Characterisation and Gas Permeance Properties

Evdokia Galata, Charitomeni M. Veziri, George V. Theodorakopoulos, ORCID,George Em. Romanos, Evangelia A. Pavlatou

Athens

Graphene oxide (GO) oligo-layered laminates were self-assembled on porous ceramic substrates via their simple dip-coating into aqueous GO dispersions. To augment the stability of the developed composite GO/ceramic membranes and control the morphology and stacking quality of the formed laminate, short-((3-glycidoxypropyl)trimethoxy silane-GLYMO, (3-aminopropyl)triethoxy silane-APTES), and long-chain (polydopamine-PDA) molecules were involved and examined as interfacial linkers. A comparative study was performed regarding the linker’s capacity to enhance the interfacial adhesion between the ceramic surface and the GO deposit and affect the orientation and assemblage characteristics of the adjacent GO nanosheets that composed the formed oligo-layered laminates. Subsequently, by post-filtrating a GO/H2O suspension through the oligo-layered laminate membranes, the respective multi-layered ones have been developed, whereas ethylenediamine (EDA) was used in the suspension as an efficient molecular linker that strongly bonds and interlocks the GO nanosheets. The definition of the best linker and approach was conducted on macroporous α-alumina disks, due to the use of inexpensive raw materials and the ability to fabricate them in the lab with high reproducibility. To validate the concept at a larger scale, while investigating the effect of the porous substrate as regards its micrometer-scale roughness and surface chemistry, specific chemical modifications that yielded membranes with the best gas permeability/selectivity performance were replicated on a commercial single-channel monolith with a ZrO2 microfiltration layer. XRD, Raman, ATR, FESEM, and XPS analyses were conducted to study the structural, physicochemical, surface, and morphological properties of the GO/ceramic composite membranes, whereas permeance results of several gases at various temperatures and trans-membrane pressures were interpreted to shed light on the pore structural features. Concerning the short-chain linkers, the obtained results ascertain that GLYMO causes denser and more uniform assembly of GO nanosheets within the oligo-layered laminate. PDA had the same beneficial effect, as it is a macromolecule. Overall, this study shows that the development of gas-separating membranes, by just dipping the linker-modified substrate into the GO suspension, is not straightforward. The application of post-filtration contributed significantly to this target and the quality of the superficially deposited, thick GO laminate depended on this of the chemically attached oligo-layered one.

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Spinelle Baikowski® Spinel S25CR

May 2022

Removal of MS2 and fr Bacteriophages Using MgAl2O4-Modified, Al2O3-Stabilized Porous Ceramic Granules for Drinking Water Treatment

Nur Sena Yüzbasi, Paweł A. Krawczyk, Kamila W. Domagała, Alexander Englert, Michael Burkhardt, Michael Stuer, Thomas Graule

Basel

Point-of-use ceramic filters are one of the strategies to address problems associated with waterborne diseases to remove harmful microorganisms in water sources prior to its consumption. In this study, development of adsorption-based ceramic depth filters composed of alumina platelets was achieved using spray granulation (calcined at 800 °C). Their virus retention performance was assessed using cartridges containing granular material (4 g) with two virus surrogates: MS2 and fr bacteriophages. Both materials showed complete removal, with a 7 log10 reduction value (LRV) of MS2 up to 1 L. MgAl2O4-modified Al2O3 granules possessed a higher MS2 retention capacity, contrary to the shortcomings of retention limits in pure Al2O3 granules. No significant decline in the retention of fr occurred during filtration tests up to 2 L. The phase composition and morphology of the materials were preserved during filtration, with no magnesium or aluminum leakage during filtration, as confirmed by X-ray diffractograms, electron micrographs, and inductively coupled plasma-optical emission spectrometry. The proposed MgAl2O4-modified Al2O3 granular ceramic filter materials offer high virus retention, achieving the criterion for virus filtration as required by the World Health Organization (LRV ≥ 4). Owing to their high thermal and chemical stability, the developed materials are thus suitable for thermal and chemical-free regeneration treatments.

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Nanodispersions Mathym® Aqueous colloidal suspensions of yttria-doped zirconia nanoparticles

19 September 2022

Transparent high-strength nanosized yttria stabilized zirconia obtained by pressure-less sintering

Omid Akhlaghi, E. Camposilvan, Zahra Gohari Bajestani, Sirous Khabbaz, Cleva W Ow-Yang, Yves Jorand, Laurent Gremillard, Vincent Garnier, Jérôme Chevalier

Lyon

This work describes the development of transparent high-strength Yttria-Stabilized Zirconia (YSZ) ceramics with ultra-fine grain size utilizing conventional pressure-less densification. Starting with nanoparticles with diameter < 10 nm, it was possible to achieve full densification (>99.5% of theoretical density) at a sintering temperature of 1100–1200 °C. The average grain size of the resulting dense ceramics was 75 nm in 3 mol. % YSZ and 85 nm in 8 mol. % YSZ, showing in-line light transmission of 38% and 51% at a wavelength of 800 nm and average biaxial strength (piston on three balls test on samples of diameter 12 mm and thickness 1 mm) of 1980 MPa and 680 MPa, respectively. The nano-grained structure, absence of color centers, and miniaturization of residual pores enable the excellent light transmission. The high biaxial strength is attributed to the refined microstructure, but also to the martensitic tetragonal-to-monoclinic phase transformation that remains active even in nano-sized zirconia grains.

Alumine ultra-pure High Purity Alumina

2014

Purification and Biocompatibility of Fermented Hyaluronic Acid for Its Applications to Biomaterials

1. Hyaluronic acid (HA) is important for pharmaceuticals and medical devices. It is used in dermal fillers, adhesion barriers, and as a carrier for cells and bioactive molecules. Purification and biocompatibility evaluations are necessary for its use in biomaterials. 2. HA was synthesized from streptococcus zooepidemicus through fermentation for 25 hours. The fermented broth was purified to remove impurities using filtration for insoluble components and various adsorbents for soluble impurities. Biocompatibility was assessed through cell counting and live/dead cell assays. 3. A 60% yield of white HA powder was obtained with an intrinsic viscosity of 15-17 dL/g and a molecular weight of around 1,000 kDa. Ultrafiltration removed low molecular weight and insoluble impurities, while adsorbents like alumina and activated carbons eliminated endotoxins, high molecular weight proteins, and nucleic acids. 4. Alumina was effective in removing endotoxins, while activated carbons were successful in eliminating high molecular weight proteins and nucleic acids. The purified HA solution showed excellent cell compatibility with no damage observed in cell proliferation and viability tests. 5. The high molecular weight HA obtained displayed excellent biocompatibility, making it suitable for biomaterial applications.

Korea

Hyaluronic acid (HA) is important for pharmaceuticals and medical devices. It is used in dermal fillers, adhesion barriers, and as a carrier for cells and bioactive molecules. Purification and biocompatibility evaluations are necessary for its use in biomaterials. HA was synthesized from streptococcus zooepidemicus through fermentation for 25 hours. The fermented broth was purified to remove impurities using filtration for insoluble components and various adsorbents for soluble impurities. Biocompatibility was assessed through cell counting and live/dead cell assays. A 60% yield of white HA powder was obtained with an intrinsic viscosity of 15-17 dL/g and a molecular weight of around 1,000 kDa. Ultrafiltration removed low molecular weight and insoluble impurities, while adsorbents like alumina and activated carbons eliminated endotoxins, high molecular weight proteins, and nucleic acids. Alumina was effective in removing endotoxins, while activated carbons were successful in eliminating high molecular weight proteins and nucleic acids. The purified HA solution showed excellent cell compatibility with no damage observed in cell proliferation and viability tests. The high molecular weight HA obtained displayed excellent biocompatibility, making it suitable for biomaterial applications.

Alumine ultra-pure Pourde d'alumine ultra-pure de la société Baikowski® (corindon)

4 Novembre 2015

Certificat d’analyse Standard Reference Material® 676a

National Institute of Standards & Technology

Gaithersburg

La poudre d'alumine Baikowski® est la référence utilisée par le NIST pour définir l'oxyde d'aluminium et généré des échantillons standards. La poudre d’alumine (voie d’alun) [NH4Al(SO4)2 • 12H2O], a été calcinée à 1400 °C et broyée par jet d'air jusqu’à un état entièrement désagrégé. Les grains d’alumine sont de taille et de forme équi-axiale. La température de calcination élevée assure la haute pureté et l’état désagrégé de ce matériau garantit l’homogénéité des mélanges préparés par des méthodes conventionnelles.

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Alumine ultra-pure BA15

Février 2022

Enhancing thermal stability of oxide ceramic matrix composites via matrix doping

Renato S.M. Almeida, H. Farhandi, K. Tushtev, K. Rezwan

Advanced Ceramics & MAPEX - Center for Materials and Processes, Universität Bremen, Germany

Journal of the European Ceramic Society

Cette étude traite de la production de composites à matrice céramique oxyde-oxyde (Ox-CMCs) en utilisant la BA15, alumine de haute pureté Baikowski. L'équipe se concentre sur la production de Ox-CMCs de plus haute stabilité thermique en employant de la poudre d'alumine dopée MgO.

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Alumine ultra-pure BMA15

Septembre 2020

Improved alumina transparency achieved by high-pressure spark plasma sintering of commercial powder

B. Ratzker, A. Wagner, S. Kalabukhov, N. Frage

Department of Materials Engineering, Ben-Gurion University of the Negev, Israel

Ceramics International 46 (2020) 21794–21799

Avec la BMA15, une alumine alpha très fine et pure, et en utilisant une technique modifiée de frittage SPS permettant d'atteindre une pression de 600MPa, il est possible de produire des pièces céramiques à grains très fins (taille de grain = 170nm), montrant une transparence optique exceptionnelle (72.6% de transmittance en ligne à longueur d'onde de 640nm, très proche de la limite théorique) à une température relativement basse de 1100°C.

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Alumine ultra-pure BMA15

July 2019

Optical and mechanical properties of transparent alumina fabricated by high-pressure spark plasma sintering

B. Ratzker, A. Wagner, M. Sokol, S. Kalabukhov, M.P. Dariel, N. Frage

Department of Materials Engineering, Ben-Gurion University of the Negev, Israel

Journal of the European Ceramic Society 39 (2019) 2712–2719

Avec la BMA15, une alumine alpha très fine et pure, et en utilisant une technique modifiée de frittage SPS permettant d'atteindre une pression de 800MPa, il est possible de produire des céramiques d’alumine transparentes (68% de transmittance en ligne) et extrêmement dures (2300HV2) à une température relativement basse de 1050°C.

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Spinelle S25CR

Janvier 2019

Gel‐casting of MgAl2O4 transparent ceramics using a common dispersant

Mengwei Liu, Shunzo Shimai, Jin Zhao, Jian Zhang, Dan Han, Yi Li, Juan Liu, Shiwei Wang

Journal of the American Ceramic Society 2019; 102: 3081– 3084

Une nouvelle forme d'élaboration des céramiques, permettant la synthèse de pièces transparentes aux formes complexes, grâce au spinelle Baikowski !

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Alumine ultra-pure CR10 - SMA6

Octobre 2017

Novel Translucent and Strong Submicron Alumina Ceramics for Dental Restorations

Zhao M, Sun Y, Zhang J, Zhang Y.

Shanghai Institute of Ceramics, China - University College of Dentistry, New York, USA

Journal of Dental Research. 2018;97(3):289-295

Une augmentation des propriétés de résistance mécanique et de transparence de céramiques dentaires est obtenue grâce à l'utilisation des alumines submicroniques de Baikowski.

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Luminophores Undoped YAG

Octobre 2017

Improving Optical Transmission of Spark-Plasma-Sintered YAG Ceramics: Effect of Powder Conditioning and Post-Treatments

R. Moronta Perez, L. Boilet, P. Aubry, P. Palmero, L. Henrard, O. Deparis, V. Lardot, F. Cambier

Belgian Ceramic Research Centre (Belgium), Department of Applied Science and Technology and INSTM Research Unit PoliTO (Italy), University of Namur (Belgium)

Journal of Ceramic Science and Technology, Vol. 9, No. 1, Pages 19-28

Etude comparative entre 3 différentes voies de synthèse pour le YAG non-dopé et propriétés associées après frittage flash SPS et optimisations.

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Alumine ultra-pure CR6

Septembre 2017

Preparation of α-Al2O3 Supports for Thin Membrane Fabrication

Topuz B, Yurttas A, Altunsoy A

Journal of the Turkish Chemical Society, Section A: Chemistry. 5. 191-204.

Production de supports macroporeux prometteurs, sans défauts macroscopiques de surface (pour les procédés de séparation) à partir d'un mélange d'alumine alpha Baikowski (CR6) et de ZnO.

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Alumine ultra-pure Alumine alpha - BA15 en suspension

Mars 2013

Highly Dense, Transparent α-Al2O3 Ceramics From Ultrafine Nanoparticles Via a Standard SPS Sintering

N. Roussel, L. Lallemant, J-Y. Chane‐Ching, S. Guillemet‐Fristch, B. Durand, V. Garnier, G. Bonnefont, G. Fantozzi, L. Bonneau, S. Trombert, D. Garcia‐Gutierrez

Journal of the American Ceramic Society, 96: 1039-1042

L'alumine alpha de Baikowski, ultrafine et de haute pureté, permet d'atteindre une haute densité pour les céramiques transparentes. Le fait d'utiliser La3+ comme dopant rend plus flexible la fabrication de céramiques transparentes sous forme de grandes pièces homogènes.

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