Research

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19 pages, 17014 KiB

Open AccessArticle

Development of Photo-Polymerization-Type 3D Printer for High-Viscosity Ceramic Resin Using CNN-Based Surface Defect Detection

by Jin-Kyo Chung, Jeong-Seon Im and Min-Soo Park

Materials 2023, 16(13), 4734; https://doi.org/10.3390/ma16134734 - 30 Jun 2023

Cited by 2 | Viewed by 1031

Abstract

Due to the high hardness and brittleness of ceramic materials, conventional cutting methods result in poor quality and machining difficulties. Additive manufacturing has also been tried in various ways, but it has many limitations. This study aims to propose a system to monitor [...] Read more.

Due to the high hardness and brittleness of ceramic materials, conventional cutting methods result in poor quality and machining difficulties. Additive manufacturing has also been tried in various ways, but it has many limitations. This study aims to propose a system to monitor surface defects that occur during the printing process based on high-viscosity composite resin that maximizes ceramic powder content in real time using image processing and convolutional neural network (CNN) algorithms. To do so, defects mainly observed on the surface were classified into four types by form: pore, minor, critical, and error, and the effect of each defect on the printed structure was tested. In order to improve the classification efficiency and accuracy of normal and defective states, preprocessing of images obtained based on cropping, dimensionality reduction, and RGB pixel standardization was performed. After training and testing the preprocessed images based on the DenseNet algorithm, a high classification accuracy of 98% was obtained. Additionally, for pore and minor defects, experiments confirmed that the defect surfaces can be improved through the reblading process. Therefore, this study presented a defect detection system as well as a feedback system for process modifications based on classified defects. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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19 pages, 5014 KiB

Open AccessArticle

Method of Determining Kinetic Parameters of Strength Recovery in Self-Healing Ceramic Composites

by Mostafizur Rahman, Taiyo Maeda, Toshio Osada and Shingo Ozaki

Materials 2023, 16(11), 4079; https://doi.org/10.3390/ma16114079 - 30 May 2023

Viewed by 1014

Abstract

Self-healing ceramic composites are promising smart materials for high-temperature applications. Experimental and numerical studies have been performed to more fully understand their behaviors, and kinetic parameters such as the activation energy and frequency factor have been reported to be indispensable for investigating healing [...] Read more.

Self-healing ceramic composites are promising smart materials for high-temperature applications. Experimental and numerical studies have been performed to more fully understand their behaviors, and kinetic parameters such as the activation energy and frequency factor have been reported to be indispensable for investigating healing phenomena. This article proposes a method of determining the kinetic parameters of self-healing ceramic composites using the oxidation kinetics model of strength recovery. These parameters are determined by an optimization method using experimental strength recovery data under various healing temperatures, times, and microstructural features on the fractured surfaces. Alumina and mullite matrix-based self-healing ceramic composites such as Al₂O₃/SiC, Al₂O₃/TiC, Al₂O₃/Ti₂AlC (MAX phase), and mullite/SiC, were selected as the target materials. The theoretical strength recovery behaviors of the cracked specimens obtained from the kinetic parameters were compared with the experimental results. The parameters were within the previously reported ranges, and the predicted strength recovery behaviors reasonably agreed with the experimental values. The proposed method can also be applied to other self-healing ceramics with matrices reinforced with different healing agents to evaluate oxidation rate, crack healing rate, and theoretical strength recovery behaviors to design self-healing materials used in high-temperature applications. Furthermore, the healing ability of composites can be discussed regardless of the type of strength recovery test. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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14 pages, 4394 KiB

Open AccessArticle

Three-Dimensional Printing of Large Ceramic Products and Process Simulation

by Tao Lin, Zhihao Zhao, Tao Wang and Ye-Tang Pan

Materials 2023, 16(10), 3815; https://doi.org/10.3390/ma16103815 - 18 May 2023

Cited by 2 | Viewed by 1597

Abstract

Ceramic 3D printing is a promising technology that overcomes the limitations of traditional ceramic molding. It offers advantages such as refined models, reduced mold manufacturing costs, simplified processes, and automatic operation, which have attracted a growing number of researchers. However, current research tends [...] Read more.

Ceramic 3D printing is a promising technology that overcomes the limitations of traditional ceramic molding. It offers advantages such as refined models, reduced mold manufacturing costs, simplified processes, and automatic operation, which have attracted a growing number of researchers. However, current research tends to focus more on the molding process and print molding quality rather than exploring printing parameters in detail. In this study, we successfully prepared a large-size ceramic blank using screw extrusion stacking printing technology. Subsequent glazing and sintering processes were used to create complex ceramic handicrafts. Additionally, we used modeling and simulation technology to explore the fluid model printed by the printing nozzle at different flow rates. We adjusted two core parameters that affect the printing speed separately: three feed rates were set to be 0.001 m/s, 0.005 m/s, and 0.010 m/s, and three screw speeds were set to be 0.5 r/s, 1.5 r/s, and 2.5 r/s. Through a comparative analysis, we were able to simulate the printing exit speed, which ranged from 0.0751 m/s to 0.6828 m/s. It is evident that these two parameters have a significant impact on the printing exit speed. Our findings show that the extrusion velocity of clay is approximately 700 times faster than the inlet velocity at an inlet velocity of 0.001–0.010 m/s. Furthermore, the screw speed is influenced by the inlet velocity. Overall, our study sheds light on the importance of exploring printing parameters in ceramic 3D printing. By gaining a deeper understanding of the printing process, we can optimize printing parameters and further improve the quality of ceramic 3D printing. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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11 pages, 2657 KiB

Open AccessArticle

New Strategy for Preparation of Yttria Powders with Atypical Morphologies and Their Sintering Behavior

by Sheng Qu, Jinlian Li and Zhaoyang Liu

Materials 2023, 16(7), 2854; https://doi.org/10.3390/ma16072854 - 03 Apr 2023

Viewed by 1008

Abstract

A modified precipitation method was used to prepare yttria powers for the fabrication of yttria ceramics in this study. The precipitation behavior, phase evolution, and shape of the yttria precursor were all examined in the presence or absence of an electric field. The [...] Read more.

A modified precipitation method was used to prepare yttria powers for the fabrication of yttria ceramics in this study. The precipitation behavior, phase evolution, and shape of the yttria precursor were all examined in the presence or absence of an electric field. The findings demonstrate that the phases of the yttria precursor were Y₂(CO₃)₃·2H₂O with and without an electric field, while the morphology changed from flake to needle-like under the action of the electric field. After calcining both yttria precursors at 750 °C, yttria powders with similar morphologies were obtained and then densified via conventional sintering (CS) and spark plasma sintering (SPS). The densification and thermal shock resistance of the yttria ceramics were investigated. The yttria ceramics sintered using SPS had higher bulk density and thermal shock resistance than the samples sintered using CS. When the sintering process for the ceramics sintered from needle-like yttria powder was switched from CS to SPS, the bulk density increased from 4.44 g·cm⁻³ to 5.01 g·cm⁻³, while the number of thermal shock tests increased from two to six. The denser samples showed better thermal shock resistance, which may be related to the fracture mechanism shifting from intergranular fracture to transgranular fracture. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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26 pages, 10631 KiB

Open AccessEditor’s ChoiceArticle

Production of Nano Hydroxyapatite and Mg-Whitlockite from Biowaste-Derived products via Continuous Flow Hydrothermal Synthesis: A Step towards Circular Economy

by Farah Nigar, Amy-Louise Johnston, Jacob Smith, William Oakley, Md Towhidul Islam, Reda Felfel, David Grant, Edward Lester and Ifty Ahmed

Materials 2023, 16(6), 2138; https://doi.org/10.3390/ma16062138 - 07 Mar 2023

Cited by 3 | Viewed by 2235

Abstract

Biowastes from agriculture, sewage, household wastes, and industries comprise promising resources to produce biomaterials while reducing adverse environmental effects. This study focused on utilising waste-derived materials (i.e., eggshells as a calcium source, struvite as a phosphate source, and CH₃COOH as dissolution [...] Read more.

Biowastes from agriculture, sewage, household wastes, and industries comprise promising resources to produce biomaterials while reducing adverse environmental effects. This study focused on utilising waste-derived materials (i.e., eggshells as a calcium source, struvite as a phosphate source, and CH₃COOH as dissolution media) to produce value-added products (i.e., calcium phosphates (CaPs) derived from biomaterials) using a continuous flow hydrothermal synthesis route. The prepared materials were characterised via XRD, FEG-SEM, EDX, FTIR, and TEM analysis. Magnesium whitlockite (Mg-WH) and hydroxyapatite (HA) were produced by single-phase or biphasic CaPs by reacting struvite with either calcium nitrate tetrahydrate or an eggshell solution at 200 °C and 350 °C. Rhombohedral-shaped Mg-WH (23–720 nm) along with tube (50–290 nm diameter, 20–71 nm thickness) and/or ellipsoidal morphologies of HA (273–522 nm width) were observed at 350 °C using HNO₃ or CH₃COOH to prepare the eggshell and struvite solutions, and NH₄OH was used as the pH buffer. The Ca/P (atomic%) ratios obtained ranged between 1.3 and 1.7, indicating the formation of Mg-WH and HA. This study showed that eggshells and struvite usage, along with CH₃COOH, are promising resources as potential sustainable precursors and dissolution media, respectively, to produce CaPs with varying morphologies. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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13 pages, 25023 KiB

Open AccessArticle

Synthesis of Ti₃SiC₂ Phases and Consolidation of MAX/SiC Composites—Microstructure and Mechanical Properties

by Jaroslaw Wozniak, Mateusz Petrus, Tomasz Cygan, Boguslawa Adamczyk-Cieślak, Dorota Moszczyńska and Andrzej Roman Olszyna

Materials 2023, 16(3), 889; https://doi.org/10.3390/ma16030889 - 17 Jan 2023

Cited by 3 | Viewed by 1343

Abstract

The article describes the Ti₃SiC₂ powder synthesis process. The influence of the molar ratio and two forms of carbon on the phase composition of the obtained powders was investigated. The synthesis was carried out using a spark plasma sintering (SPS) [...] Read more.

The article describes the Ti₃SiC₂ powder synthesis process. The influence of the molar ratio and two forms of carbon on the phase composition of the obtained powders was investigated. The synthesis was carried out using a spark plasma sintering (SPS) furnace. In addition, using the obtained powders, composites reinforced with SiC particles were produced. The obtained results showed no effect of the carbon form and a significant impact of annealing on the purity of the powders after synthesis. The composites were also consolidated using an SPS furnace at two temperatures of 1300 and 1400 °C. The tests showed low density and hardness for sinters from 1300 °C (maximum 3.97 g/cm³ and 447 HV5, respectively, for composite reinforced with 10% SiC). These parameters significantly increase for composites sintered at 1400 °C (maximum density 4.43 g/cm³ and hardness 1153 HV5, for Ti₃AlC₂—10% SiC). In addition, the crack propagation analysis showed mechanisms typical for granular materials and laminates. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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9 pages, 2019 KiB

Open AccessArticle

Synthesis of Octacalcium Phosphate Containing Glutarate Ions with a High Incorporation Fraction

by Taishi Yokoi, Masahiro Watanabe, Tomoyo Goto, Sikun Meng, Tohru Sekino, Masaya Shimabukuro and Masakazu Kawashita

Materials 2023, 16(1), 64; https://doi.org/10.3390/ma16010064 - 21 Dec 2022

Cited by 4 | Viewed by 1805

Abstract

Octacalcium phosphate (OCP) has received considerable attention in the field of ceramic biomaterials as an advanced functional material. It exhibits a layered structure composed of apatitic and hydrated layers and can incorporate various dicarboxylate ions into the hydrated layer. Saturated dicarboxylic acids (HOOC(CH [...] Read more.

Octacalcium phosphate (OCP) has received considerable attention in the field of ceramic biomaterials as an advanced functional material. It exhibits a layered structure composed of apatitic and hydrated layers and can incorporate various dicarboxylate ions into the hydrated layer. Saturated dicarboxylic acids (HOOC(CH₂)_nCOOH) with an odd number of methylene groups (–CH₂–) exhibit lower incorporation fractions than those with an even number of methylene groups, possibly owing to a compositional dependence on the synthetic method. In this study, calcium carbonate, phosphoric acid, and various amounts of glutaric acid were used to produce glutarate-ion-incorporated OCP by a wet chemical method, which is different from the conventional synthetic strategy. While utilising 1–20 mmol of glutaric acid during synthesis did not produce the desired product, using 25 mmol of glutaric acid resulted in the formation of single-phase glutarate-ion-incorporated OCP with a Ca/P molar ratio of 1.57 and a 90% incorporation fraction of glutarate ions. This glutarate-ion-incorporation fraction is significantly higher than that reported in the previous studies (35%). Thus, the synthetic procedure proposed herein was able to produce single-phase OCP containing glutarate ions with a high incorporation fraction. Our findings can contribute to development of novel functional ceramic biomaterials in the future. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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16 pages, 6763 KiB

Open AccessArticle

Synthesis and Properties of the Gallium-Containing Ruddlesden-Popper Oxides with High-Entropy B-Site Arrangement

by Juliusz Dąbrowa, Jan Adamczyk, Anna Stępień, Marek Zajusz, Karolina Bar, Katarzyna Berent and Konrad Świerczek

Materials 2022, 15(18), 6500; https://doi.org/10.3390/ma15186500 - 19 Sep 2022

Cited by 4 | Viewed by 1748

Abstract

For the first time, the possibility of obtaining B-site disordered, Ruddlesden–Popper type, high-entropy oxides has been proven, using as an example the LnSr(Co,Fe,Ga,Mn,Ni)O₄ series (Ln = La, Pr, Nd, Sm, or Gd). The materials were synthesized using the Pechini method, followed by [...] Read more.

For the first time, the possibility of obtaining B-site disordered, Ruddlesden–Popper type, high-entropy oxides has been proven, using as an example the LnSr(Co,Fe,Ga,Mn,Ni)O₄ series (Ln = La, Pr, Nd, Sm, or Gd). The materials were synthesized using the Pechini method, followed by sintering at a temperature of 1200 °C. The XRD analysis indicated the single-phase, I4/mmm structure of the Pr-, Nd-, and Sm-based materials, with a minor content of secondary phase precipitates in La- and Gd-based materials. The SEM + EDX analysis confirms the homogeneity of the studied samples. Based on the oxygen non-stoichiometry measurements, the general formula of LnSr(Co,Fe,Ga,Mn,Ni)O_4+δ, is established, with the content of oxygen interstitials being surprisingly similar across the series. The temperature dependence of the total conductivity is similar for all materials, with the highest conductivity value of 4.28 S/cm being reported for the Sm-based composition. The thermal expansion coefficient is, again, almost identical across the series, with the values varying between 14.6 and 15.2 × 10⁻⁶ K⁻¹. The temperature stability of the selected materials is verified using the in situ high-temperature XRD. The results indicate a smaller impact of the lanthanide cation type on the properties than has typically been reported for conventional Ruddlesden–Popper type oxides, which may result from the high-entropy arrangement of the B-site cations. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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16 pages, 3527 KiB

Open AccessEditor’s ChoiceArticle

Novel SrO-Containing Glass-Ceramic Sealants for Solid Oxide Electrolysis Cells (SOEC): Their Design and Characterization under Relevant Conditions

by Hassan Javed, Elisa Zanchi, Fabiana D’Isanto, Chiara Bert, Domenico Ferrero, Massimo Santarelli and Federico Smeacetto

Materials 2022, 15(17), 5805; https://doi.org/10.3390/ma15175805 - 23 Aug 2022

Cited by 1 | Viewed by 1608

Abstract

This study presents results on the development of strontium oxide (SrO) containing glass sealants used to join Crofer22APU to yttria-stabilized zirconia (3YSZ), in which the main glass components, that is, silicon oxide (SiO₂), strontium oxide (SrO), calcium oxide (CaO) and aluminum [...] Read more.

This study presents results on the development of strontium oxide (SrO) containing glass sealants used to join Crofer22APU to yttria-stabilized zirconia (3YSZ), in which the main glass components, that is, silicon oxide (SiO₂), strontium oxide (SrO), calcium oxide (CaO) and aluminum oxide (Al₂O₃), have been varied appropriately. Certain properties, such as the crystallization behavior, the coefficient of thermal expansion, adhesion, and reactivity of the sealants in contact with Crofer22APU, have been reviewed and discussed. The optimized glass composition (with CTE in the 9.8–10.3 × 10⁻⁶ K⁻¹ range) results in a good joining behavior by hindering the formation of undesirable strontium chromate (SrCrO₄) on contact with the Crofer22APU steel after 1000 h. at 850 °C. High specific resistivity values of about 10⁶ Ohm.cm have been obtained, thus demonstrating good insulating properties at 850 °C under an applied voltage of 1.6 V. A negligible degradation in the electrical resistivity trend was measured during the test up to 1000 h, thus excluding the presence of detrimental reactions of the glass-ceramic sealant in contact with Crofer22APU under a dual atmosphere, as confirmed using SEM-EDS post-mortem analyses. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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9 pages, 1407 KiB

Open AccessArticle

Advanced and Functional Structured Ceramics: MgF₂ and ZnS

by Natalia Kamanina, Andrey Toikka, Yaroslav Barnash, Pavel Kuzhakov and Dmitry Kvashnin

Materials 2022, 15(14), 4780; https://doi.org/10.3390/ma15144780 - 07 Jul 2022

Cited by 5 | Viewed by 1616

Abstract

Due to difficulties in obtaining monomaterials, intensive research into the properties of ceramic compositions has been undertaken, along with developments to the properties of the compositions. These are not inferior to monomeric structures for a number of basic parameters. Among the different types [...] Read more.

Due to difficulties in obtaining monomaterials, intensive research into the properties of ceramic compositions has been undertaken, along with developments to the properties of the compositions. These are not inferior to monomeric structures for a number of basic parameters. Among the different types of ceramics, magnesium fluoride and zinc sulfide occupy a special place due to their unique properties and specific applications. In this paper, we studied functional optoelectronics and modulating technique elements based on the advanced ceramics MgF₂ and ZnS. The results of the transmittance spectral parameters and the contact angle estimation as well as an AFM analysis of the studied ceramics, both pure and structured with carbon nanotubes, are presented. We observed that the main characteristics of the studied materials with a surface modified by carbon nanotubes could be significantly changed when an innovative laser-oriented deposition method was applied. This method permitted the CNTs to be deposited in a vertical position on the material surface. The main features of the carbon nanotubes—such as the smaller value of the refractive index, the greater strength between the carbon atoms, and the effective surface—were taken into consideration. The analytical, quantum chemical, and experimental results of the studies of the changes in the basic physical parameters of the selected model of the inorganic matrices of the ceramics are given. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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13 pages, 2150 KiB

Open AccessArticle

Synthesis, Structure–Property Evaluation and Biological Assessment of Supramolecular Assemblies of Bioactive Glass with Glycyrrhizic Acid and Its Monoammonium Salt

by Alimjon D. Matchanov, Rakhmat S. Esanov, Tobias Renkawitz, Azamjon B. Soliev, Elke Kunisch, Isabel Gonzalo de Juan, Fabian Westhauser and Dilshat U. Tulyaganov

Materials 2022, 15(12), 4197; https://doi.org/10.3390/ma15124197 - 13 Jun 2022

Cited by 6 | Viewed by 1599

Abstract

Medical nutrients obtained from plants have been used in traditional medicine since ancient times, owning to the protective and therapeutic properties of plant extracts and products. Glycyrrhizic acid is one of those that, apart from its therapeutic effect, may contribute to stronger bones, [...] Read more.

Medical nutrients obtained from plants have been used in traditional medicine since ancient times, owning to the protective and therapeutic properties of plant extracts and products. Glycyrrhizic acid is one of those that, apart from its therapeutic effect, may contribute to stronger bones, inhibiting bone resorption and improving the bone structure and biomechanical strength. In the present study, we investigated the effect of a bioactive glass (BG) addition to the structure–property relationships of supramolecular assemblies formed by glycyrrhizic acid (GA) and its monoammonium salt (MSGA). FTIR spectra of supramolecular assemblies evidenced an interaction between BG components and hydroxyl groups of MSGA and GA. Moreover, it was revealed that BG components may interact and bond to the carboxyl groups of MSGA. In order to assess their biological effects, BG, MSGA, and their supramolecular assemblies were introduced to a culture of human bone-marrow-derived mesenchymal stromal cells (BMSCs). Both the BG and MSGA had positive influence on BMSC growth, viability, and osteogenic differentiation—these positive effects were most pronounced when BG1d-BG and MSGA were introduced together into cell culture in the form of MSGA:BG assemblies. In conclusion, MSGA:BG assemblies revealed a promising potential as a candidate material intended for application in bone defect reconstruction and bone tissue engineering approaches. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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16 pages, 3676 KiB

Open AccessEditor’s ChoiceArticle

Osteogenic Potential of Magnesium (Mg)-Doped Multicomponent Bioactive Glass: In Vitro and In Vivo Animal Studies

by Saeid Kargozar, Peiman Brouki Milan, Moein Amoupour, Farzad Kermani, Sara Gorgani, Simin Nazarnezhad, Sara Hooshmand and Francesco Baino

Materials 2022, 15(1), 318; https://doi.org/10.3390/ma15010318 - 03 Jan 2022

Cited by 21 | Viewed by 3454

Abstract

The use of bioactive glasses (BGs) has been quite fruitful in hard tissue engineering due to the capability of these materials to bond to living bone. In this work, a melt-derived magnesium (Mg)-doped BG (composition: 45SiO₂–3P₂O₅–26CaO–15Na₂ [...] Read more.

The use of bioactive glasses (BGs) has been quite fruitful in hard tissue engineering due to the capability of these materials to bond to living bone. In this work, a melt-derived magnesium (Mg)-doped BG (composition: 45SiO₂–3P₂O₅–26CaO–15Na₂O–7MgO–4K₂O (mol.%)) was synthesized for being used in bone reconstruction. The prepared BGs were then manufactured as three-dimensional (3D) scaffolds by using the sponge replica approach. The microstructure of the samples was assessed by X-ray diffraction (XRD) and the surface morphology was observed by using scanning electron microscopy (SEM). The in vitro bioactivity and the release of osteo-stimulatory Mg²⁺ ions from the prepared samples were investigated over 7 days of incubation in simulated body fluids (SBF). In vitro cellular analyses revealed the compatibility of the Mg-doped BGs with human osteosarcoma cells (MG-63 cell line). Moreover, the Mg-doped BGs could induce bone nodule formation in vitro and improve the migratory ability of human umbilical vein endothelial cells (HUVECs). In vivo osteogenic capacity was further evaluated by implanting the BG-derived scaffolds into surgically-created critical-size bone defects in rats. Histological and immunohistological observations revealed an appropriate bone regeneration in the animals receiving the glass-based scaffolds after 12 weeks of surgery. In conclusion, our study indicates the effectiveness of the Mg-doped BGs in stimulating osteogenesis in both in vitro and in vivo conditions. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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Review

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38 pages, 2637 KiB

Open AccessReview

A Selective Review of Ceramic, Glass and Glass–Ceramic Protective Coatings: General Properties and Specific Characteristics for Solar Cell Applications

by Rebekah Fraser and Mihaela Girtan

Materials 2023, 16(11), 3906; https://doi.org/10.3390/ma16113906 - 23 May 2023

Viewed by 1631

Abstract

A review on ceramics, glasses and glass–ceramics as thin film protective coatings for solar cells is given. The different preparation techniques and the physical and chemical properties are presented in a comparative way. This study is useful for technologies involving solar cells and [...] Read more.

A review on ceramics, glasses and glass–ceramics as thin film protective coatings for solar cells is given. The different preparation techniques and the physical and chemical properties are presented in a comparative way. This study is useful for technologies involving solar cells and solar panel cell development at the industrial scale, because protective coatings and encapsulation play a major role in increasing the lifetime of solar panels and environmental protection. The aim of this review article is to give a summary of existing ceramic, glass, and glass–ceramic protective coatings and how they apply to solar cell technology: silicon, organic or perovskite cells. Moreover, some of these ceramic, glass or glass–ceramic layers were found to have dual functionality, such as providing anti-reflectivity or scratch resistance to give a two-fold improvement to the lifetime and efficiency of the solar cell. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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26 pages, 6079 KiB

Open AccessReview

Nanocrystalline Alumina-Zirconia-Based Eutectic Ceramics Fabricated with High-Energy Beams: Principle, Solidification Techniques, Microstructure and Mechanical Properties

by Zhi-Gang Wang, Yun-Zhuo Zhang, Jia-Hu Ouyang, Xi-Wen Song, Min Xie, Ya-Ming Wang and Yu-Jin Wang

Materials 2023, 16(8), 2985; https://doi.org/10.3390/ma16082985 - 09 Apr 2023

Cited by 2 | Viewed by 2266

Abstract

Nanocrystalline alumina-zirconia-based eutectic ceramics fabricated with high-energy beams and composed of ultrafine, three-dimensionally entangled, single-crystal domains are a special category of eutectic oxides that exhibit exceptionally high-temperature mechanical properties, such as strength and toughness as well as creep resistance. This paper aims to [...] Read more.

Nanocrystalline alumina-zirconia-based eutectic ceramics fabricated with high-energy beams and composed of ultrafine, three-dimensionally entangled, single-crystal domains are a special category of eutectic oxides that exhibit exceptionally high-temperature mechanical properties, such as strength and toughness as well as creep resistance. This paper aims to provide a comprehensive review on the basic principles, advanced solidification processes, microstructure and mechanical properties of alumina-zirconia-based eutectic ceramics, with particular attention to the status of the art on a nanocrystalline scale. Some basic principles of coupled eutectic growth are first introduced based on previously reported models, followed by concise introduction of solidification techniques and the control strategy of solidification behavior from the processing variables. Then, the microstructural formation of nanoeutectic structure is elucidated with regard to different hierarchical scales, and mechanical properties such as hardness, flexural and tensile strength, fracture toughness and wear resistance are discussed in detail for a comparative study. Nanocrystalline alumina-zirconia-based eutectic ceramics with unique microstructural and compositional characteristics have been produced with high-energy beam-based processes, and in many cases, promising improvements in mechanical performance have been reported as contrasting with conventional eutectic ceramics. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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30 pages, 1927 KiB

Open AccessEditor’s ChoiceReview

Frontiers of Hydroxyapatite Composites in Bionic Bone Tissue Engineering

by Jingcun Shi, Wufei Dai, Anand Gupta, Bingqing Zhang, Ziqian Wu, Yuhan Zhang, Lisha Pan and Lei Wang

Materials 2022, 15(23), 8475; https://doi.org/10.3390/ma15238475 - 28 Nov 2022

Cited by 11 | Viewed by 2416

Abstract

Bone defects caused by various factors may cause morphological and functional disorders that can seriously affect patient’s quality of life. Autologous bone grafting is morbid, involves numerous complications, and provides limited volume at donor site. Hence, tissue-engineered bone is a better alternative for [...] Read more.

Bone defects caused by various factors may cause morphological and functional disorders that can seriously affect patient’s quality of life. Autologous bone grafting is morbid, involves numerous complications, and provides limited volume at donor site. Hence, tissue-engineered bone is a better alternative for repair of bone defects and for promoting a patient’s functional recovery. Besides good biocompatibility, scaffolding materials represented by hydroxyapatite (HA) composites in tissue-engineered bone also have strong ability to guide bone regeneration. The development of manufacturing technology and advances in material science have made HA composite scaffolding more closely related to the composition and mechanical properties of natural bone. The surface morphology and pore diameter of the scaffold material are more important for cell proliferation, differentiation, and nutrient exchange. The degradation rate of the composite scaffold should match the rate of osteogenesis, and the loading of cells/cytokine is beneficial to promote the formation of new bone. In conclusion, there is no doubt that a breakthrough has been made in composition, mechanical properties, and degradation of HA composites. Biomimetic tissue-engineered bone based on vascularization and innervation show a promising future. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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