Ceramic Processing Method Research Articles

РАЗРАБОТКА КОМБИНИРОВАННОЙ ШТИФТОВО-КУЛЬТЕВОЙ ВКЛАДКИ ДЛЯ РЕАЛИЗАЦИИ ЗУБОСОХРАНЯЮЩЕГО ПОДХОДА ПРИ ЛЕЧЕНИИ ПАЦИЕНТОВ С ДЕФЕКТАМИ ТВЕРДЫХ ТКАНЕЙ ЗУБОВ

Subject. The possibility of improving the pin-stump lay made using modern digital technologies. Reconstruction of the aesthetic defect of the tooth crown is one of the most important aspects in the work of an orthopedic dentist. Pin-stump designs make it possible to preserve your own teeth. However, the designs used today have a large number of disadvantages. The article defines the main required characteristics and proposes a modified combined pin-stump lay. The technology of manufacturing this type of prosthesis using modern additive methods is presented. Objectives. is to develop and introduce into the practice of orthopedic dentistry an improved design of a combined pin-stump lay made using modern digital technologies. Methodology. During the development, the design of the pin-stump lay was modified by improving the fixing elements in their location and geometric shape. Automated digital programs are used to simulate the pin-stump lay. A method of selective laser sintering of metal from cobalt-chromium powder has been applied to convert it to an analog. The ceramic stump part is implemented by pressing ceramics using traditional technology. Results. A useful model of a combined pin-stump lay has been developed. A step-by-step manufacturing process using the capabilities of modern technologies in orthopedic dentistry is proposed. The advantages of the design at each stage of manufacture are described, ensuring a good result of orthopedic treatment. Conclusions. The combined pin-stump lay developed as a result of the study has a number of advantages. The use of software for volumetric modeling increases the accuracy of manufacturing this orthopedic structure. Selective laser sintering makes it possible to obtain high strength characteristics. The ceramic processing method has a positive effect on the aesthetics parameter at the final stage of prosthetics.

Chemistry and Physics of Wet Foam Stability for Porous Ceramics: A Review

The unique structural properties of porous ceramics, such as low thermal conductivity, high surface area, controlled permeability, and low density, make this material valuable for a wide range of applications. Its uses include insulation, catalyst carriers, filters, bio-scaffolds for tissue engineering, and composite manufacturing. However, existing processing methods for porous ceramics, namely replica techniques and sacrificial templates, are complex, release harmful gases, have limited microstructure control, and are expensive. In contrast, the direct foaming method offers a simple and cost-effective approach. By modifying the surface chemistry of ceramic particles in a colloidal suspension, the hydrophilic particles are transformed into hydrophobic ones using surfactants. This method produces porous ceramics with interconnected pores, creating a hierarchical structure that is suitable for applications like nano-filters. This review emphasizes the importance of interconnected porosity in developing advanced ceramic materials with tailored properties for various applications. Interconnected pores play a vital role in facilitating mass transport, improving mechanical properties, and enabling fluid or gas infiltration. This level of porosity control allows for the customization of ceramic materials for specific purposes, including filtration, catalysis, energy storage, and biomaterials.

3D-printed polymer-derived ceramics with tunable cellular architectures

Ceramic materials possess high mechanical strength and environmental stability, but their brittleness limits their suitability for structural applications. A solution lies in using polymer-derived ceramics (PDCs), which offer enhanced toughness and versatility in shaping unlike traditional ceramic processing methods. This study explores tunable ceramic cellular architectures based on triply periodic minimal surface (TPMS) designs, fabricated via stereolithography (SLA) using a silicon oxycarbide precursor formulated for vat photopolymerization. By combining the preceramic polymer with a photoinitiator, crosslinkers, and other additives, intricate shapes are 3D-printed and then pyrolyzed under nitrogen, resulting in PDCs with complex TPMS geometries. The toughness, strength, and stiffness of the 3D-printed structures are evaluated through quasi-static compression experiments. Comprehensive material and microstructural characterizations of the PDCs are performed pre- and post-pyrolysis, employing visual inspection, X-ray micro-tomography, thermogravimetric analysis, energy dispersive X-ray spectroscopy, density, and rheological measurements. Optimization of 3D printing and pyrolysis parameters yields ceramic structures with 2.2 MPa compressive strength and 330 MPa stiffness with a lattice density of 0.5 g cm-3. The ceramic material, including porosity, had a maximum density of 1.63 ± 0.01 g cm-3. This low-cost SLA 3D printing technique is ideal for creating thin features and customized structures of bio-inspired, architectured ceramics. Furthermore, the process exhibits excellent printability, being compatible with common and cost-effective SLA, DLP, and LCD 3D printers.

Review: Tailored microstructures in the system tricalcium phosphate-wollastonite-diopside for bone regeneration scaffolds

Tissue engineering constructs (TECs) combining resorbable scaffolds, cells and/or reactive agents are required for bone regeneration. New green ceramic processing methods allow fabricating layered and gradient porous structures. Dense bioceramics with sufficient strength that keep their microstructure when incorporating porosity are required. Bioceramics in the system tricalcium phosphate-wollastonite-diopside are reviewed. Tailoring of microstructures to improve their mechanical and biological behaviors and their potential for TECs are analyzed. First, a brief discussion on bone properties and requirements for biomaterials and the capabilities and limits of glasses and glass-ceramics formulated in the system is done. Then, the relationships between the microstructure and the mechanical behavior of single-phase and composite bioceramics are discussed. TCP-D-W microstructures with adequate mechanical performance support viability and osteogenic differentiation of human mesenchymal stem cells (hASCs) and their colonization by hASCs presents specific morphological features that make them adequate for TECs.

The influence of sintering condition on microstructure, phase composition, and electrochemical performance of the scandia-ceria-Co-doped zirconia for SOFCs

Samples of 6 mol% Sc2O3 - 1 mol% CeO2 co-doped ZrO2 were fabricated by conventional ceramic processing methods and sintered at various temperatures from 1000 to 1650?C in air. The sintering conditions on microstructure and phase content are investigated using various characterization methods, including pycnometry, diffraction, and spectroscopy. The electrical conductivity of samples was investigated using electrochemical impedance spectroscopy (EIS). The effect of inductive load (measured from room temperature to 800?C) is discussed in low to high temperature regimes. At T<400?C since the arc is not a complete semicircle, the high-frequency arc could be fit using a constant phase element (CPE), while by subtraction of inductive load, a good fit is achieved using a capacitor element instead of CPE. The Arrhenius conductivity plot of samples reveals that the specimen sintered at 1600?C for 6 hours exhibits the highest conductivity. The activation energy (Ea) and conductivity preexponential (?0) factor are calculated from a linear fit to data that decreases by the increase in sintering temperature.

Mitigating grain growth in fully stabilized zirconia via a two-step sintering strategy for esthetic dental restorations.

Overall, 8-mol% yttria-stabilized zirconia (8YSZ), unlike 3YSZ, is optically transparent and stable against low-temperature degradation but has insufficient mechanical properties due to its large grain size. The influence of the grain size of 8YSZ on mechanical properties was investigated to develop an 8YSZ suitable for dental restoration. Modulation of the grain size and relative density was achieved via a two-step sintering (TSS) process, and the corresponding kinetic window was established. The conditions of TSS employed herein yielded a relative density of more than 99% while maintaining a small grain size of 0.75 μm. On the other hand, the highest biaxial strength and the highest total transmittance attained were 833 MPa and 34.6% (1-mm-thick, 39.1% for a 0.5-mm thick sample) in the TSS 8YSZ with a grain size of 1.25 μm. These results suggest that strength has improved only when grain size reduction and increased relative density are achieved at the same time. The results demonstrate that the ceramic processing method has a significant effect on the mechanical and optical properties of 8YSZ needed for dental restoration and provide a new insight that contrasts previous studies focused on the starting material.

Solid state processing of the cantor derived alloy CoCrFeMnNi by oxide reduction

In recent years, high entropy alloys (HEAs), also known has Multi-Principal Element Alloys (MPEAs) have emerged as a new and exciting class of materials. One of the first (and most widely studied) HEA compositions is that of the so-called Cantor alloy, the equimolar CoCrFeNiMn composition. This paper reports on the synthesis of an HEA containing the same metallic elements via reduction of a mixture of the corresponding oxides. High purity precursor powders of Co(OH)2, Cr2O3, Fe2O3, MnO2, and NiO were milled and mixed using standard ceramic processing methods. The green pellets were subjected to a series of isothermal reduction anneals in flowing 3% H2–Ar (which is below the flammability limit), at temperatures ranging from 1000 to 1185 °C, with annealing times from 24 to 120 h. The microstructure and phase evolution of the samples were characterized using SEM, EDS analysis, and XRD. Reduction heat-treatment at 1185 °C resulted in samples developing a core-shell structure, with a dense outer metallic layer, and a core consisting of a mixture of metallic and ceramic phases. Using EPMA (electron microprobe analysis), the composition of the HEA shell was determined to be Co0·25Cr0·19Fe0·25Ni0·23Mn0.08. The hardness of the HEA was measured using Vickers micro-indentation. Examination of the individual indentation sites showed a strong positive correlation between the hardness value and the volume fraction of second phase particles (MnCr2O4, Cr2O3) within the indented area. A comparison between two sub-groups of indentation sites showed an 43% increase in average hardness (211.1 HV versus 148 HV) that was associated with a higher volume fraction of second phase (10.9% versus 2.9%). Consistent with thermodynamic considerations, experiments revealed that when a sample consisting solely of MnO2 was subjected to the same conditions, reduction to metallic Mn did not take place. A model is put forward whereby the free energy change related to the formation of the HEA solid solution provides an additional driving force for the reaction.

Metal Supported Electrolysis Cells

Solid oxide electrolyser (SOE) technology can become a key player in energy systems, with increasing shares of electricity from fluctuating sources such as wind and solar, contributing to power grid balance and energy storage as well as providing green fuels for transportation. Most mature SOE configurations are electrolyte supported or fuel electrode supported. Metal supported SOE cell configurations are an interesting concept for decreasing costs and increasing robustness. The present study compares fuel electrode supported and metal supported cells in terms of performance and durability under SOE conditions. Special emphasis was on medium temperature operating conditions of 650 °C. Metal supported cells, fabricated using ceramic processing methods, showed a better performance compared to state-of-the-art (SoA) cells with Ni/YSZ fuel electrode supported configuration, fabricated by tape casting and screen printing, under steam electrolysis conditions at 700 and 650 °C. The area specific cell resistance (ASR) was lower by ca. 20% for the metal supported cell in 50% H2O in H2 vs. air at 650 °C. Furthermore, the metal supported cells showed a stable performance—even a slight activation—during long-term steam electrolysis tests over 500 h at 650 °C and −0.25 and −0.5 A/cm2, while the SoA reference cell degraded with 13%/1000 h under the same conditions.

Dental Ceramics

Dental restorations associated with the development of novel microstructures for ceramic materials have caused an important change in the clinical workflow for dentists and technicians, as well as in the treatment options offered to patients. New microstructures have also been developed by the industry to offer ceramic and composite materials with optimized properties, i.e. good mechanical properties, appropriate wear behavior, and acceptable esthetic characteristics. The objective of this literature review is to discuss the main advantages and disadvantages of the new ceramic systems and processing methods.

Fabrication of high-density and translucent Al-containing garnet, Li7−xLa3Zr2−xTaxO12 (LLZTO) solid-state electrolyte by pressure filtration and sintering

Garnet type LLZTO ceramic oxide is a promising solid-state electrolyte for use in Li-ion batteries because it has good chemical stability, adequate mechanical strength. However, lithium dendrite growth still needs to be addressed. The opacity of the solid electrolyte hinders in-situ investigation of dendrite growth. Therefore, semi-transparent LLZTO with high-density is needed. The traditional fabrication process for the garnet type LLZTO is cumbersome, and dense LLZTO disks with high transparency are difficult to fabricate. In this work, Al-LLZTO powder was made by solid-state reaction. A wet ceramic processing method, pressure filtration followed by sintering, was developed to make dense LLZTO with high ionic conductivity (1.47 × 10−4 S/cm) and adequate transmittance (17–23%) to visible light from 500 to 800 nm to observe and monitor dendrite growth.

Structural, nonlinear electrical characteristics, and stability against DC-accelerated aging stress behavior of Er-doped 20 nm ZnO-Bi2 O3 -Mn2 O3 -based varistors.

In this research, ZnO-Bi2 O3 -Mn2 O3 varistors manufactured from 20 nm ZnO powder and doped with different amounts of Er2 O3 were fabricated via the conventional ceramic processing method. The effect of various Er2 O3 concentrations (0.5-2.0mol%) on the sintered density, structural improvement, and nonlinear behavior of the 20 nm ZnO-Bi2 O3 -Mn2 O3 varistors was discussed. Different Er2 O3 concentrations exerted considerable influence on the varistors. The addition of large amounts of Er2 O3 led to the inhibition of grain growth by increasing the amount of the Er2 O3 -rich spinel phase. X-ray diffraction analysis showed that the addition of Er2 O3 to the varistor systems led to the development of Er2 O3 -rich phases during sintering. During sintering, the considerable surface area of the nanoparticle powder resulted in numerous interactions in the surfaces of the ceramics manufactured from 20 nm ZnO powder. The electrical behaviors of the varistors were substantially influenced by Er2 O3 . E1 mA evidently increased from 2,144.7 to 5,482.2V/mm with the increment in doping amount. The nonlinear coefficient also dramatically increased with the increase in Er2 O3 content. The ZnO nanoparticle-Bi2 O3 -Mn2 O3 varistors doped with 1.0-2.0mol% Er2 O3 possessed high voltage and nonlinearity and were stable against DC-accelerated aging stress.

(Invited) All-Solid-State Batteries Using Li7La3Zr2O12 Garnet Electrolyte Framework

All-solid-state batteries (ASSB) using LLZO (variants of Li7La3Zr2O12) garnet solid electrolyte with lithium metal anode potentially offer higher energy density and improved safety. Rational design of cell architecture as well as manufacturing scalability are key aspects to consider as the technology readiness level advances. A thick composite cathode layer attached to a thin solid electrolyte layer is desirable to obtain superior energy densities. Furthermore, the architecture within the composite cathode may be engineered to contain directional conduction paths of lithium ions or electrons for enhanced rate capabilities.Here, we demonstrate a functioning bulk-type LLZO based all-solid-state battery with a practical form factor incorporating the above described design concepts. Freeze-tape-casting (FTC), a scalable and environmentally friendly ceramic processing method, is used to construct 3D porous LLZO scaffolds composed of vertical arrays of LLZO walls. The thin solid-electrolyte layer is fabricated by tape-casting (TC). By sintering the stacks of FTC and TC green tapes, porous/dense bilayers and porous/dense/porous trilayers of LLZO frameworks are obtained. An ASSB was constructed using a porous/dense bilayer by infiltrating LiNi0.6Mn0.2Co0.2O2 cathode powder and carbon black into the porous layer and adhering lithium metal foil to the dense side. We find it crucial to introduce a plastic crystal based soft solid electrolyte to the porous layer to electrochemically connect all cathode components, obviating the need for co-sintering to establish contact. The soft nature of the plastic crystal based solid-electrolyte may be able to accommodate the volume change of the cathode material as it cycles. In this device, which contained no liquid component, the initial discharge capacities were similar to those observed in a lithium ion battery configuration using the same cathode powder at C/10 rates.

Structural, Morphological and Dielectric Spectroscopy Analysis of Double Perovskite Bi2MnNiO6 Electronic Material

Exploring as well as examining novel functional double perovskite material represents an important aspect in the field of electronic devices. In this present study the electronic material Bi2MnNiO6 has been framed through high temperature solid state ceramic processing method. Its electronic structure, morphological and electrical characteristics has been evaluated. Its structure is found to be monoclinic through XRD analysis. The uniform and compact grain distribution has been observed form the micrographs. The impedance analysis of the ceramic suggests negative temperature coefficient of resistance behaviour. The important electrical properties associated with this compound may be essential in the development of next generation electronic devices.

Dependence of the nonlinear behaviour stability of a ZnO nanoparticle-Bi2 O3 -Mn2 O3 -based varistor system on cooling rates during ceramic processing.

A conventional ceramic processing method was applied to manufacture high-density 20-nm ZnO-Bi2 O3 -Mn2 O3 varistor ceramics. Different cooling rates in the range of 135-540°C/h led to a relatively slight influence on the microstructure, varistor voltage, and leakage current. In contrast, these rates strongly affected the nonlinear exponent. The specific surface area of the 20-nm ZnO nanoparticle may have led to an intense solid-state reaction even at a low cooling rate. Superior nonlinearity, with 59.7 μA nonlinear current leakage and 273.5 μA leakage current, was achieved at the 135°C/h cooling rate. The differences in the cooling rates led to a remarkable change in the material's stability under direct current (DC)-accelerated aging stress in the following order: 135°C/hr ˃ 270°C/hr˃405°C/hr ˃ 540°C/hr.

Capacitive behavior of lead free BiNdMnNiO6 double perovskite electronic material

Abstract An effective and simple method has been developed to synthesize the lead free BiNdMnNiO6 double perovskite material. The synthesis has been carried out through the conventional high-temperature solid-state ceramic processing method. The crystal structure formation has been confirmed with the help of the powder X-ray diffraction method which shows that at room temperature the ceramic exhibits a monoclinic structure. Dielectric and impedance spectroscopy methods have been used to study the significances of frequency and temperature on the conduction mechanism of the ceramic material. The variations of tangent loss and dielectric at different frequencies have been carried out to study the capacitive behavior of the ceramic material. From its impedance study, the existence of a negative temperature coefficient has been affirmed. The important physiochemical properties associated with this compound may be very much essential in the development of next-generation electronic devices.

Cerâmica dentária: uma revisão de novos materiais e métodos de processamento.

A evolução dos sistemas informatizados para a produção de restaurações dentárias associadas ao desenvolvimento de novas microestruturas para materiais cerâmicos causou uma mudança importante no fluxo de trabalho clínico de dentistas e técnicos, bem como nas opções de tratamento oferecidas aos pacientes. Novas microestruturas também foram desenvolvidas pela indústria para oferecer materiais cerâmicos e compósitos com propriedades otimizadas, ou seja, boas propriedades mecânicas, comportamento adequado ao desgaste e características estéticas aceitáveis. O objetivo desta revisão de literatura é discutir as principais vantagens e desvantagens dos novos sistemas cerâmicos e métodos de processamento. O manuscrito está dividido em cinco partes: I) restaurações monolíticas de zircônia; II) próteses dentárias multicamadas; III) novas vitrocerâmicas; IV) cerâmica infiltrada por polímero; e V) novas tecnologias de processamento. As cerâmicas dentárias e as tecnologias de processamento evoluíram significativamente nos últimos dez anos, com a maior parte da evolução relacionada a novas microestruturas e métodos CAD-CAM. Além disso, uma tendência ao uso de restaurações monolíticas mudou a maneira como os médicos produzem próteses dentárias totalmente em cerâmica, uma vez que as restaurações mais estéticas em várias camadas, infelizmente, são mais propensas a lascar ou delaminar. Os materiais compósitos processados ​​via CAD-CAM tornaram-se uma opção interessante, pois possuem propriedades intermediárias entre cerâmica e polímeros e são mais facilmente fresados ​​e polidos.

A novel ceramic derived processing route for Multi-Principal Element Alloys

In recent years, Multi-Principal Element Alloys (MPEAs) have emerged as a new and exciting class of materials. To date, the most widely used processing methods for MPEAs are arc melting and mechanical alloying. The study explores the feasibility of an alternative, novel process to process bulk MPEA samples, namely the reduction of an oxide powder precursor mix. Equiatomic CuCoFeNi was selected as a model system of study because these elements form a subset of a large proportion of MPEA compositions already studied. High purity precursor oxide powders of Co3O4, CuO, Fe2O3 and NiO were milled and mixed using standard ceramic processing methods. The green pellets were subjected to a reduction annealing treatment in flowing 5%H2–N2 at 1000 °C, with heat-treatment times ranging from 4 to 1000 h. After 4 h, the sample was transformed into a dense metallic bulk sample with no residual oxides. The microstructure was characterized by x-ray EDS, SEM and XRD, and was shown to consist of a polycrystalline matrix, and a copper-rich second phase situated at the triple points. The hardness was studied by nano-indentation. Using EPMA (electron microprobe analysis), the composition of the matrix was determined to be Cu18.1Co26.6Fe26.9Ni28.4 (at%), which represents the single phase MPEA composition. Oxide reduction is a viable technique for processing bulk complex metallic alloys, with potential for novel microstructural tailoring.

Electrical Discharge Machining Non-Conductive Ceramics: Combination of Materials

One of the promising processing methods for non-conductive structural and functional ceramics based on ZrO2, Al2O3, and Si3N4 systems is electrical discharge machining with the assistance of an auxiliary electrode that can be presented in the form of conductive films with a thickness up to 4–10 µm or nanoparticles - granules, tubes, platelets, multidimensional particles added in the working zone as a free poured powder the proper concentration of which can be provided by ultrasound emission or by dielectric flows or as conductive additives in the structure of nanocomposites. However, the described experimental approaches did not reach the production market and industry. It is related mostly to the chaotic development of the knowledge and non-systematized data in the field when researchers often cannot ground their choice of the material for auxiliary electrodes, assisting powders, or nano additives or they cannot explain the nature of processes that were observed in the working tank during experiments when their results are not correlated to the measured specific electrical conductivity of the electrodes, particles, ceramic workpieces or nanocomposites but depends on something else. The proposed review includes data on the main electrophysical and chemical properties of the components in the presence of heat when the temperature in the interelectrode gap reaches 10,000 °C, and the systematization of data on ceramic pressing methods, including spark plasma sintering, the chemical reactions that occur in the interelectrode gap during sublimation of primary (brass and copper) and auxiliary electrodes made of transition metals Ti, Cr, Co, and carbon, auxiliary electrodes made of metals with low melting point Zn, Ag, Au, Al, assisting powder of oxide ceramics TiO2, CeO2, SnO2, ITO, conductive additives Cu, W, TiC, WC, and components of Al2O3 and Zr2O workpieces in interaction with the dielectric fluid - water and oil/kerosene medium.

3D printing of transparent YAG ceramics using copolymer-assisted slurry

Transparent YAG ceramics were successfully formed by 3D printing using a 2.33 wt% ISOBAM per mixed powder assisted aqueous slurry with 72 wt% solids-loading. The 3D printing process enabled the fabrication of complex-shaped transparent YAG ceramics and did not require the use of cold isostatic pressing (CIP), hot isostatic pressing (HIP), or additional tooling. The fabricated ceramics achieved an in-line transmittance of 70% in the visible wavelength range and relative density of 99.7%, which was similar to that achieved by CIP ceramic processing methods. 3D printing ceramics with an ISOBAM assisted slurry could simplify the fabrication process of transparent ceramics with complex shapes.

Effect of the sintering temperature on the microstructure and superconducting properties of MgB2 bulks manufactured by the field assisted sintering technique

Magnesium diboride (MgB2) bulk superconductors may have practical applications as permanent magnets owing to their ability to trap larger fields than conventional ferromagnets and a transition temperature of 39 K that make them attractive for use in cryogen-free systems. Unlike the cuprate high temperature superconductors, grain boundaries in MgB2 act as pinning sites not weak links, and so show good current carrying ability in polycrystalline samples. This enables the materials to be processed using standard ceramic processing methods which are scalable to large diameters and mass production. The maximum trapped field in bulk superconductors scales with the critical current density (Jc) of the material as well as the radius of the sample. To obtain the highest possible Jc values in MgB2 at high fields requires the bulk materials to be fully dense but fine-grained material, and possibly with a nano-scale distribution of non-superconducting impurity particles to further enhance pinning. Field assisted sintering technology (FAST) is a rapid process for obtaining dense ceramics from materials like MgB2 which are difficult to sinter with conventional pressure-less techniques. Rapid heat treatments are attractive both from a manufacturing point of view and because the total time that the sample is held at high temperature is short, limiting grain coarsening. In this paper, we report a systematic study of the influence of processing temperature on microstructure and superconducting properties of MgB2 bulks manufactured using FAST. We conclude that processing temperatures above 1000 °C are required to obtain materials that have sufficiently high electrical connectivity to generate large magnetic moments. However, the intrinsic (intragrain) Jc values in MgB2 are better in the samples processed at 900 °C owing to their finer scale microstructures and the MgB2 lattice being more defective.