Ceramics

Research

20 pages, 6177 KiB

Open AccessArticle

Characterization of the Evolution with Temperature of the Structure and Properties of Geopolymer-Cordierite Composites

by Franklin Casarrubios, Alexandre Marlier, Charlotte Lang, Sandra Abdelouhab, Isabella Mastroianni, Geoffroy Bister and Maurice-François Gonon

Ceramics 2024, 7(4), 1513-1532; https://doi.org/10.3390/ceramics7040098 - 17 Oct 2024

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Abstract

This work is part of a research project aimed at producing ceramic-like materials, without the need for an initial sintering, for potential applications in catalysis or filtration at temperatures up to 1000 °C. In that context, cordierite-derived materials were prepared from recycled cordierite [...] Read more.

This work is part of a research project aimed at producing ceramic-like materials, without the need for an initial sintering, for potential applications in catalysis or filtration at temperatures up to 1000 °C. In that context, cordierite-derived materials were prepared from recycled cordierite powder (automotive industry waste) bonded with metakaolin-potassium silicate geopolymer. The principle is that these materials, prepared at temperatures below 100 °C, acquire their final properties during the high-temperature commissioning. The focus is on the influence of the K/Al ratio and cordierite fraction on the stability of the dimensions and porosity during heating at 1000 °C, and on the final Young’s modulus and coefficient of thermal expansion. Conventional and high-temperature XRD evidenced the absence of crystallization of the geopolymer binder and interaction with the cordierite filler during the heating stage when K/Al = 1 or 0.75. By contrast, crystallization of kalsilite and leucite, and diffusion of potassium ions in the structure of cordierite is evidenced for K/Al = 1.5 and 2.3. These differences strongly influence the shrinkage due to sintering and the final properties. It is shown that a K/Al ratio of 0.75 or 1 is favorable to the stability of the porosity, around 25 to 30%. Moreover, a low coefficient of thermal expansion of 4 to 4.5 × 10⁻⁶ K⁻¹ and a Young’s modulus of 40 to 45 GPa is obtained. Full article

(This article belongs to the Special Issue Innovative Manufacturing Processes of Silicate Materials)

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24 pages, 14405 KiB

Open AccessArticle

Advanced Refinement of Geopolymer Composites for Enhanced 3D Printing via In-Depth Rheological Insights

by Abrar Gasmi, Christine Pélegris, Ralph Davidovits, Mohamed Guessasma, Hugues Tortajada and Florian Jean

Ceramics 2024, 7(4), 1316-1339; https://doi.org/10.3390/ceramics7040087 - 27 Sep 2024

Cited by 2 | Viewed by 903

Abstract

The advancement of 3D printing technology has been remarkable, yet the quality of printed prototypes heavily relies on the rheological behavior of the materials used. This study focuses on optimizing geopolymer-based composite formulas to achieve high-quality 3D printing, with particular attention given to [...] Read more.

The advancement of 3D printing technology has been remarkable, yet the quality of printed prototypes heavily relies on the rheological behavior of the materials used. This study focuses on optimizing geopolymer-based composite formulas to achieve high-quality 3D printing, with particular attention given to rheological analysis. Three metakaolins, Argical M1200s, Metamax, and Tempozz M88, were used as alumino-silicate precursors for the preparation of the geopolymer binders. Rheological studies were conducted on viscosity, shear stress, and responses to oscillations in amplitude and frequency. The Tempozz M88-based binder was identified as the most effective for the extrusion due to its optimal rheological properties. Subsequently, the study investigated the influence of the amount, up to 55%, and morphology of the fillers, comprising feldspar and wollastonite, on the rheology of the pastes. Also, the addition of Xanthan gum, a gelling agent in the geopolymer paste, was analyzed, revealing improved extrusion quality and more stable bead structures. Finally, a comprehensive comparison was carried out between two formulations chosen according to rheological observations, utilizing image sequences captured during 3D printing. This comparison highlighted the formulation that ensures structural stability, design accuracy, and minimized sagging. This study underscores the significance of geopolymer formula optimization, leveraging rheology as a pivotal tool to enhance 3D printing quality, thereby facilitating more precise and reliable applications of additive manufacturing. Full article

(This article belongs to the Special Issue Innovative Manufacturing Processes of Silicate Materials)

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15 pages, 31081 KiB

Open AccessArticle

Non-Uniform Drying Shrinkage in Robocasted Green Body Ceramic Products

by Nicolas Lauro, Arnaud Alzina, Benoit Nait-Ali and David S. Smith

Ceramics 2024, 7(3), 1122-1136; https://doi.org/10.3390/ceramics7030073 - 22 Aug 2024

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Abstract

The formation of defects, due to drying, in robocasted ceramic objects is an important issue arising from non-uniform shrinkage of the material during this step in the process. Common methods for shrinkage measurement are not well suited to the small size of robocasted [...] Read more.

The formation of defects, due to drying, in robocasted ceramic objects is an important issue arising from non-uniform shrinkage of the material during this step in the process. Common methods for shrinkage measurement are not well suited to the small size of robocasted cords or the complexity of robocasted objects. Innovative methods for shrinkage measurement were developed using non-destructive optical vision techniques with computer-controlled data acquisition, allowing measurement on millimetric cords and on specific zones of a product. The study of a single porcelain cord revealed an anisometric shrinkage related to the orientation of grains during extrusion. A differential shrinkage at the macroscopic scale was also measured on a robocasted object, indicating a moisture content gradient in the material. The methods presented in this paper are of particular relevance to real-time control of the drying process for robocasted objects. Full article

(This article belongs to the Special Issue Innovative Manufacturing Processes of Silicate Materials)

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20 pages, 12602 KiB

Open AccessArticle

The Mechanical Properties of Geopolymers as a Function of Their Shaping and Curing Parameters

by Camille Zoude, Elodie Prud’homme, Kévyn Johannes and Laurent Gremillard

Ceramics 2024, 7(3), 873-892; https://doi.org/10.3390/ceramics7030057 - 25 Jun 2024

Cited by 1 | Viewed by 830

Abstract

This study investigates the impact of curing conditions, porosity and shaping techniques on the mechanical properties of metakaolin-based geopolymers. Geopolymers offer versatility in shaping, including 3D printing, yet the influence of curing conditions after printing on mechanical properties remains unclear. This is assessed [...] Read more.

This study investigates the impact of curing conditions, porosity and shaping techniques on the mechanical properties of metakaolin-based geopolymers. Geopolymers offer versatility in shaping, including 3D printing, yet the influence of curing conditions after printing on mechanical properties remains unclear. This is assessed by measuring the bending properties of 3D-printed metakaolin-based geopolymer filaments cured under varied humidity and temperature conditions. The influences of porosity and of shaping technique are observed by comparing the compression properties of molded and 3D-printed samples of various porosity. Samples cured at low humidity exhibit unusually high mechanical properties, which decrease when moved from a dry to a humid environment. This behavior may be due to the presence of PEG within the composition and/or to residual stresses due to the too rapid evacuation of water. High humidity is therefore necessary to ensure optimal curing and stable properties. Increasing the curing temperature helps accelerate geopolymerization without significantly compromising mechanical properties. Direct ink writing offers design flexibility and suitable porosity, but the samples appear to exhibit different failure mechanisms than the molded samples. Additional studies are necessary to understand the interactions between PEG and the geopolymer as well as to better identify the fracture mechanisms within the different samples. Full article

(This article belongs to the Special Issue Innovative Manufacturing Processes of Silicate Materials)

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14 pages, 4561 KiB

Open AccessArticle

Mullite 3D Printed Humidity Sensors

by Yurii Milovanov, Arianna Bertero, Bartolomeo Coppola, Paola Palmero and Jean-Marc Tulliani

Ceramics 2024, 7(2), 807-820; https://doi.org/10.3390/ceramics7020053 - 10 Jun 2024

Cited by 1 | Viewed by 1305

Abstract

Mullite substrates with two different porosities were 3D printed, and tested as humidity sensors. To evaluate the effects of porosity on humidity sensitivity, the samples were sintered at 1400 °C (Sensor 1) and 1450 °C (Sensor 2). The sensors were tested in a [...] Read more.

Mullite substrates with two different porosities were 3D printed, and tested as humidity sensors. To evaluate the effects of porosity on humidity sensitivity, the samples were sintered at 1400 °C (Sensor 1) and 1450 °C (Sensor 2). The sensors were tested in a range from 0% to 85% relative humidity (RH) at room temperature. When exposed to water vapor at room temperature, the impedance value dropped down from 155 MΩ under dry air to 480 kΩ under 85 RH% for Sensor 1 and from 115 MΩ under dry air to 410 kΩ for Sensor 2. In addition, response time and recovery time were below 2 min, whatever the firing temperature, when RH changed from 0% to 74%. Finally, tests carried out involving ammonia, methane, carbon dioxide and nitrogenous oxide, as well as ethanol and acetone, showed no interference. Full article

(This article belongs to the Special Issue Innovative Manufacturing Processes of Silicate Materials)

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11 pages, 3903 KiB

Open AccessArticle

Fabrication of Dicarboxylic-Acid- and Silica-Substituted Octacalcium Phosphate Blocks with Stronger Mechanical Strength

by Yuki Sugiura, Yasuko Saito, Etsuko Yamada and Masanori Horie

Ceramics 2024, 7(2), 796-806; https://doi.org/10.3390/ceramics7020052 - 7 Jun 2024

Cited by 1 | Viewed by 1326

Abstract

Octacalcium phosphate (OCP) is an attractive base material to combine into components developed for medical purposes, especially those used in bone replacement procedures, not only because of its excellent biocompatibility but also because of its ability to intercalate with multiple types of molecular [...] Read more.

Octacalcium phosphate (OCP) is an attractive base material to combine into components developed for medical purposes, especially those used in bone replacement procedures, not only because of its excellent biocompatibility but also because of its ability to intercalate with multiple types of molecular layers such as silica, dicarboxylic acid, and various cations. On the other hand, there are no examples of simultaneous substituting for several different compounds on OCPs. Therefore, in this study, the physical and mechanical strength (DTS: diametral tensile strength) of OCPs substituted with both silica and dicarboxylic acids (thiomalate: SH-malate) were evaluated. By optimizing the amount of SH-malate, we were able to prepare a block consisting of OCPs with both silica and SH-malate supported in the interlayer. The composition of the OCP-based compound comprising this block was Ca₈Na_1.07H_6.33(PO₄)_4.44(SiO₄)_1.32(SH-malate)_2.40·nH₂O. Interestingly, the low mechanical strength, a drawback of silica-substituted OCP blocks, could be improved by dicarboxylic acid substituting. The dicarboxylic acid addition increased the mechanical strength of silica-substituted OCP blocks, and the acid successfully incorporated into the interlayer, even with the presence of silica. These results are expected to advance the creation of better silica-substituted OCPs and improved bone replacement materials. Full article

(This article belongs to the Special Issue Innovative Manufacturing Processes of Silicate Materials)

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17 pages, 7052 KiB

Open AccessArticle

Ultra-Broadband Plasmon Resonance in Gold Nanoparticles Precipitated in ZnO-Al₂O₃-SiO₂ Glass

by Georgiy Shakhgildyan, Leon Avakyan, Grigory Atroshchenko, Maxim Vetchinnikov, Alexandra Zolikova, Elena Ignat’eva, Mariam Ziyatdinova, Elena Subcheva, Lusegen Bugaev and Vladimir Sigaev

Ceramics 2024, 7(2), 562-578; https://doi.org/10.3390/ceramics7020037 - 25 Apr 2024

Cited by 1 | Viewed by 1682

Abstract

Optical materials with a tunable localized surface plasmon resonance (LSPR) are of great interest for applications in photonics and optoelectronics. In the present study, we explored the potential of generating an LSPR band with an ultra-broad range of over 1000 nm in gold [...] Read more.

Optical materials with a tunable localized surface plasmon resonance (LSPR) are of great interest for applications in photonics and optoelectronics. In the present study, we explored the potential of generating an LSPR band with an ultra-broad range of over 1000 nm in gold nanoparticles (NPs), precipitated through a thermal treatment in ZnO-Al₂O₃-SiO₂ glass. Using optical absorption spectroscopy, we demonstrated that the LSPR band’s position and shape can be finely controlled by varying the thermal treatment route. Comprehensive methods including Raman spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy were used to study the glass structure, while computational approaches were used for the theoretical description of the absorption spectra. The obtained results allowed us to suggest a scenario responsible for an abnormal LSPR band broadening that includes a possible interparticle plasmonic coupling effect taking place during the liquid–liquid phase separation of the heat-treated glass. The formation of gold NPs with an ultra-broad LSPR band in glasses holds promise for sensitizing rare earth ion luminescence for new photonics devices. Full article

(This article belongs to the Special Issue Innovative Manufacturing Processes of Silicate Materials)

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13 pages, 5438 KiB

Open AccessArticle

Analysis of the Structure and Durability of Refractory Castables Impregnated with Sodium Silicate Glass

by Jurgita Malaiškienė, Valentin Antonovič, Renata Boris, Andrius Kudžma and Rimvydas Stonys

Ceramics 2023, 6(4), 2320-2332; https://doi.org/10.3390/ceramics6040142 - 4 Dec 2023

Cited by 1 | Viewed by 2619

Abstract

This study examines the impact of the impregnation of fireclay-based conventional (CC) and medium-cement castables (MCCs) with liquid sodium silicate glass under vacuum conditions. The goal is to assess how this treatment affects the physical and mechanical properties and durability (alkali and thermal [...] Read more.

This study examines the impact of the impregnation of fireclay-based conventional (CC) and medium-cement castables (MCCs) with liquid sodium silicate glass under vacuum conditions. The goal is to assess how this treatment affects the physical and mechanical properties and durability (alkali and thermal shock resistance) of these castables used in biomass combustion boilers, where they are exposed to temperatures up to 1100 °C. The research work employs standard test methods to evaluate the physical and mechanical properties. Additionally, advanced techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and specific tests for alkali resistance and thermal shock resistance are used. The research findings suggest that impregnation with sodium silicate glass under vacuum significantly enhances the alkali resistance of both CC and MCCs. This improvement is primarily due to the reduction in porosity and the increase in density. SEM images reveal that the impregnated samples are coated with a glassy layer and the pores are partially filled with sodium silicate. Tests for alkali resistance demonstrate the formation of a protective glassy layer (with a thickness of 0.9–1.5 mm) on the castable surfaces, thereby reducing the further penetration of alkali into deeper layers of the samples. However, it is important to mention that the impregnated refractory castables have reduced resistance to thermal shock cycles. Full article

(This article belongs to the Special Issue Innovative Manufacturing Processes of Silicate Materials)

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