M. Saadi, Alianna Maguire, Neethu T. Pottackal
et al.
Additive manufacturing (AM) has gained significant attention due to its ability to drive technological development as a sustainable, flexible, and customizable manufacturing scheme. Among the various AM techniques, direct ink writing (DIW) has emerged as the most versatile 3D printing technique for the broadest range of materials. DIW allows printing of practically any material, as long as the precursor ink can be engineered to demonstrate appropriate rheological behavior. This technique acts as a unique pathway to introduce design freedom, multifunctionality, and stability simultaneously into its printed structures. Here, a comprehensive review of DIW of complex 3D structures from various materials, including polymers, ceramics, glass, cement, graphene, metals, and their combinations through multimaterial printing is presented. The review begins with an overview of the fundamentals of ink rheology, followed by an in‐depth discussion of the various methods to tailor the ink for DIW of different classes of materials. Then, the diverse applications of DIW ranging from electronics to food to biomedical industries are discussed. Finally, the current challenges and limitations of this technique are highlighted, followed by its prospects as a guideline toward possible futuristic innovations.
Annalena Erlacher, Adrian Villalba Weinberg, Christian L. Lengauer
et al.
Ti-stabilized alumina-zirconia eutectic ceramics produced by fusion-casting are characterized to investigate microstructural mechanisms at elevated temperatures and to explain the self-sharpening effect. Scanning electron microscopy (SEM) images show fine-grained lamellar eutectic microstructures with well-defined domains. After thermal annealing at 800 °C, distinct cracks formed along the domain boundaries. Thermal analyses and powder X-ray diffraction (pXRD), using Rietveld evaluation, confirmed that the cracks are triggered by the phase transformation from meta-stable tetragonal to monoclinic ZrO2, causing a volume increase of up to 13.4 %. This indicates a decrease in the stabilizing effect of Ti in the meta-stable tetragonal ZrO2 starting from 669 °C, and subsequently triggering the phase transformation. Additionally, structural analysis of pXRD data reveals internal stresses within the crystal lattice, showing expansion of tetragonal ZrO2 along the c-axis and distortions in the basal plane in both tetragonal and monoclinic ZrO2.
Recent advancements in taphole clay binder development have focused on replacing toxic coal tar/pitch, which contains polycyclic aromatic hydrocarbons (PAH), with greener alternatives. In this study, three different taphole clays were prepared in the laboratory using different binder systems which include phenolic resin: 1) coal tar, 2) glycerine, and 3) petroleum waxy oil. The clays were evaluated and compared to the conventional coal tar and phenolic resin-containing clay used in platinum smelters. The evaluation methods employed included workability and extrusion pressure ageing, hardenability, strength development, and high-temperature properties, which comprised cold crushing strength after ageing at 200 °C, carbon yield, volatile organic compound concentration and apparent porosity. The results indicated that the preferred binder to replace coal tar was glycerine, as this clay retained both its plasticity and hardenability during ageing, while also attaining comparative strength development and high-temperature properties to those of the reference clay containing coal tar.
Spray flame synthesis offers a promising method for scalable production of homogeneously mixed Y2O3-MgO nanopowders as next-generation infrared-transparent window material, which has attracted significant attention owing to its excellent optical properties at high temperatures. However, systematic understanding of how flame synthesis parameters influence particle morphology, crystal phase, solid solubility, and subsequent ceramic performance remains insufficiently understood. In this study, we investigated the influence of precursor chemistry on particle crystal phase and examined the solid solubility of MgO in Y2O3 under different flame temperatures, demonstrating that the high-temperature conditions with O2 as dispersion gas allow up to 50 mol% MgO to fully dissolve into Y2O3, far exceeding the equilibrium solubility limit of 7 mol% at the eutectic temperature (2100°C) and near-zero at room temperature. Furthermore, we systematically evaluated how powder characteristics and sintering parameters-including powder deagglomeration methods, vacuum sintering temperature, hot isostatic pressing (HIP) temperature, and initial powder characteristics-affect ceramic microstructures and infrared transmittance. Despite cracking induced by phase transformation and finer particle sizes, ceramics fabricated from oxygen-synthesized monoclinic-dominated powders exhibited superior near-infrared transmittance (56.2% at 1550 nm), attributed to enhanced atomic mixing and effective grain boundary pinning. After optimization, pure cubic phase powders produced intact and crack-free ceramics with outstanding mid-infrared transparency, achieving a maximum transmittance of 84.6% and an average transmittance of 82.3% in 3-5 um range.
Materials obtained from nature are divided into two groups: natural and artificial. Materials fall into four main categories: metals, ceramics, polymers, and composites. Glass is a solid material that is transparent, usually rigid, fragile, and has an inorganic amorphous structure that allows the preservation of liquids. Ceramics, on the other hand, are solid materials containing metal and non-metal inorganic compounds with ionic or covalent bonds. Nontechnical ceramics fall into three general groups: cement and concrete, fired clay, minerals, and stone. Fibers and particles are utilized as strengthening constituents in different types of composite materials. Hybrids can be used as different types of composite materials and thermal insulation parts. Hybrid materials are divided into four groups: composites, foams, honeycombs, and natural materials. Composites and foams can be made from metallic, ceramic, or polymer-based matrices. Metals and their alloys are materials connected by metallic bonds. Metals are divided into two groups: ferrous and non-ferrous. A polymer is a substance comprised of enormous molecules. Polymers have larger molecular masses than small molecule compounds. Polymers are materials connected by covalent bonds and dominant van der Waals bonds. Polymeric materials are divided into two groups: elastomers and plastics. Plastics (polymers) are divided into two main parts: thermoplastics and thermosets. Thermoplastics can be reused when heated due to their weak bonds, meaning they are suitable for recycling. A thermoset is a thermosetting polymer and is a material attained by permanently hardening the resin. Industrial usage areas of polymers include textiles, electronic goods, the automotive industry, healthcare, building materials, and food. In this study, polymeric materials were defined, then classified and their usage areas were criticized.
Nanostructured hybrid functional perovskite materials are an exciting domain of electroceramic materials and have created attention among researchers due to the coexistence of multiple properties like piezo and ferroelectricity. It offers a broad range of applications in optics and electronics technology. One of its kinds, bismuth sodium titanate (Bi0·5Na0·5TiO3-BNT) nanomaterials, possesses an integral and significant role in advanced electronic industries. This article aims to systemize the deliberation related to the development of bismuth sodium titanate-based nanomaterials, including the study of nanomaterial morphology mechanism, fabrication methods, crystal structure, and its role in many other novel applications. This work focuses on analyzing behavior based on synthesis methods, the proposed approaches for optimizing morphology, and current challenges. Challenges and opportunities connected with the BNT nanomaterials are elaborated. This study could motivate young researchers to study and develop novel BNT-based nanomaterials so that we could get the best out of the research.
The generation and evaluation of severely high thermal stress (σ) is known to be responsible for failure of thermal barrier coatings (TBCs) during thermal cycling. It is crucial and challenging to capture fluctuations in σ caused by the phase transition, which has motivated us to develop a high-throughput multiscale evaluation method for σ in TBCs that considers the phase transition of the top ceramic materials by coupling first-principles calculations with finite element simulations. The method quantitatively evaluates and visualizes σ of the real TBC structure under thermal cycling by multifield coupling. Additionally, the thermophysical properties calculated by the first-principles calculations consider the effects of temperature and phase transition, which not only reduces the cost of obtaining data but also has a more physical connotation. In this work, rare earth tantalites (RETaO4) are introduced as ceramic layers, and the results demonstrate that σ undergoes a rapid escalation near the phase transition temperature (Tt), particularly in the TBCs_GdTaO4 system, where it rises from 224 to 435 MPa. This discontinuity in σ may originate from the significant alterations in Young’s modulus (increase by 27%–78%) and thermal conductivity (increase by 53%–146%) near Tt. The TBCs_NdTaO4 and TBCs_SmTaO4 systems exhibit noteworthy temperature drop gradients and minimal σ fluctuations, which are beneficial for extending service lifetime of TBCs. This approach facilitates the prediction of failure mechanisms and provides theoretical guidance for the reverse design of TBC materials to obtain low thermal stress systems.
Oleksandr S. Pylypchuk, Serhii E. Ivanchenko, Mykola Y. Yelisieiev
et al.
We revealed the anomalous temperature behavior of the giant dielectric permittivity and unusual frequency dependences of the pyroelectric response of the fine-grained ceramics prepared by the spark plasma sintering of the ferroelectric BaTiO3 nanoparticles. The temperature dependences of the electro-resistivity indicate the frequency-dependent transition in the electro-transport mechanisms between the lower and higher conductivity states accompanied by the maximum in the temperature dependence of the loss angle tangent. The pyroelectric thermal-wave probing revealed the existence of the spatially inhomogeneous counter-polarized ferroelectric state at the opposite surfaces of the ceramic sample. We described the temperature behavior of the giant dielectric response and losses using the core-shell model for ceramic grains, effective medium approach and Maxwell-Wagner approach. The superparaelectric-like state with a giant dielectric response may appear due to the internal barrier-layer capacitance effect, while the step-like thermal activation of localized polarons in the semiconducting grains is not excluded. The elucidation of the state microscopic origin requires measurements in the frequency range above 1 MHz.
Accurate industry classification is critical for many areas of portfolio management, yet the traditional single-industry framework of the Global Industry Classification Standard (GICS) struggles to comprehensively represent risk for highly diversified multi-sector conglomerates like Amazon. Previously, we introduced the Multi-Industry Simplex (MIS), a probabilistic extension of GICS that utilizes topic modeling, a natural language processing approach. Although our initial version, MIS-1, was able to improve upon GICS by providing multi-industry representations, it relied on an overly simple architecture that required prior knowledge about the number of industries and relied on the unrealistic assumption that industries are uncorrelated and independent over time. We improve upon this model with MIS-2, which addresses three key limitations of MIS-1 : we utilize Bayesian Non-Parametrics to automatically infer the number of industries from data, we employ Markov Updating to account for industries that change over time, and we adjust for correlated and hierarchical industries allowing for both broad and niche industries (similar to GICS). Further, we provide an out-of-sample test directly comparing MIS-2 and GICS on the basis of future correlation prediction, where we find evidence that MIS-2 provides a measurable improvement over GICS. MIS-2 provides portfolio managers with a more robust tool for industry classification, empowering them to more effectively identify and manage risk, particularly around multi-sector conglomerates in a rapidly evolving market in which new industries periodically emerge.
Kai Wang, Roger A. De Souza, Xiang-Long Peng
et al.
Dopants can significantly affect the properties of oxide ceramics through their impact on the property-determined microstructure characteristics such as grain boundary (GB) segregation, space charge layer formation in the GB vicinity, and the grain growth deviating from normal patterns. To support the rational design of oxide ceramics, we propose a defect-chemistry-informed phase-field grain growth model to simulate the microstructure evolution of oxide ceramics. It fully respects the defect-chemistry theory by accounting for the distinct segregation energies and available site densities of charged point defects (oxygen vacancies and acceptor dopants) in both the grain interior and boundaries, and it considers the competing kinetics of defect diffusion and GB movement. The proposed phase-field model is benchmarked against well-known bicrystal models, including the Mott-Schottky and Gouy-Chapman models. Various simulation results are presented to reveal the effect of different defect-chemistry parameters on the space charge layer formation and key microstructural aspects. In particular, simulation results confirm that the solute drag effect alone can lead to skewed grain size distribution that do not follow the log-normal distribution, without any contribution from grain misorientation and other anisotropy. Interestingly, simulations also demonstrate that grain boundary potentials can vary substantially: GBs of larger grains tend to have lower potentials than those of smaller grains. Such heterogeneous GB potential distribution may inspire a new material optimization strategy through microstructure design. This study provides a comprehensive framework for defect-chemistry-consistent investigations of microstructure evolution in polycrystalline oxide ceramics, offering fundamental insights into microscopic processes during critical manufacturing stages.
Dariia G. Chernomorets, Andreana Piancastelli, Laura Esposito
et al.
Yttrium oxide has multiple applications both as a transparent material with good optical, mechanical, and thermal properties, and for photonics when doped with rare earth ions. To achieve full transparency, a careful control of the process, from the selection of powders to the final densification by sintering, is required. In this context, the characteristics of the starting powders have a great impact on the final properties. In the present work, the effect of milling conditions of two commercial Y2O3 powders on the properties of ceramics obtained by cold isostatic pressing (CIP) and vacuum sintering was investigated. The milling rate varied between 80 and 300 rpm, and the milling time between 1 and 22 h. It was found that the optimal treatment conditions are 300 rpm for 65 min, which provided a homogeneous nano-sized Y2O3 powder. IR-transparent Y2O3 ceramics obtained by a vacuum sintering have a transmittance of 78.30% (1100 nm).
J. C. Guzmán-Mínguez, V. Fuertes, C. Granados-Miralles
et al.
With an annual production amounting to 800 kilotons, ferrite magnets constitute the largest family of permanent magnets in volume, a demand that will only increase as a consequence of the rare-earth crisis. With the global goal of building a climate-resilient future, strategies towards a greener manufacturing of ferrite magnets are of great interest. A new ceramic processing route for obtaining dense Sr-ferrite sintered magnets is presented here. Instead of the usual sintering process employed nowadays in ferrite magnet manufacturing that demands long dwell times, a shorter two-step sintering is designed to densify the ferrite ceramics. As a result of these processes, dense SrFe$_{12}$O$_{19}$ ceramic magnets with properties comparable to state-of-the-art ferrite magnets are obtained. In particular, the SrFe$_{12}$O$_{19}$ magnet containing 0.2% PVA and 0.6% wt SiO$_2$ reaches a coercivity of 164 kA/m along with a 93% relative density. A reduction of 31% in energy consumption is achieved in the thermal treatment with respect to conventional sintering, which could lead to energy savings for the industry of the order of 7.109 kWh per year.
Generally, the superconductivity was expected to be absent in magnetic systems, but this reception was disturbed by unconventional superconductors, such as cuprates, iron-based superconductors and recently discovered nickelate, since their superconductivity is proposed to be related to the electron-electron interaction mediated by the spin fluctuation. However, the coexistence of superconductivity and magnetism is still rare in conventional superconductors. In this work, we reported the coexistence of these two quantum orderings in high entropy carbide ceramics (Mo0.2Nb0.2Ta0.2V0.2W0.2)C0.9, (Ta0.25Ti0.25Nb0.25Zr0.25)C, and they are expected to be conventional superconductors. Clear magnetic hysteresis loop was observed in these high entropy carbides, indicating a ferromagnetic ground state. A sharp superconducting transition is observed in (Mo0.2Nb0.2Ta0.2V0.2W0.2)C0.9 with a Tc of 3.4 K and upper critical field of ~3.35 T. Meanwhile, superconductivity is suppressed to some extent and zero-resistance state disappears in (Ta0.25Ti0.25Nb0.25Zr0.25)C, in which stronger magnetism is presented. The upper critical field of (Ta0.25Ti0.25Nb0.25Zr0.25)C is only ~1.5 T, though they show higher transition temperature near 5.7 K. The ferromagnetism stems from the carbon vacancies which occurs often during the high temperature synthesis process. This work not just demonstrate the observation of superconductivity in high entropy carbide ceramics, but also provide alternative exotic platform to study the correlation between superconductivity and magnetism, and is of great benefit for the design of multifunctional electronic devices.
Lead zirconate titanate (PZT, [Formula: see text]) is a piezoelectric ceramic which can be used for several applications such as actuators, sensors, and microelectronic devices. Depending on its composition, PZT can exhibit rhombohedral, orthorhombic (tetragonal) phases, with the piezoelectric charge constant ([Formula: see text]) key to evaluating its piezoelectric properties. In this study, ([Formula: see text]) was calculated using density functional perturbation theory (DFPT) based on first-principles methods. First, we reveal that the rhombohedral structure is stable for Zr-rich compositions. Second, extending the study to [Formula: see text] and [Formula: see text] (PSZT), we evaluated the values of [Formula: see text] both theoretically and experimentally to investigate how they are affected by doping. The microscopic movements of individual atoms within the optimized crystal were analyzed to investigate the correlations between the structural characteristics and [Formula: see text]. The results show that the relative positions of Ti and Zr (B-site) atoms and the quadratic elongation in the PZT octahedron depend strongly on the piezoelectric charge constant [Formula: see text], which itself depends on the Ti content. The local atomic structural parameters described in this study can be used as a descriptor for the high-throughput screening of PZT materials.
Yinusa Daniel Lamidi, Seun Samuel Owoeye, Segun Michael Abegunde
In this present study, synthetic tobermorites are prepared using bio-waste (snail shell) and municipal waste (container glasses) as lime and silica precursors respectively. Six batch compositions were formulated with varying combination of soda-lime glass and snail shell ash. The bodies were sintered at 950 °C for a holding period of 2 h in an electric muffle furnace. Analyses such as scanning electron microscopy (SEM/EDS), Fourier Transform Infra-red Spectroscopy (FT-IR), X-ray diffractometry (XRD) were used to assess the microstructure, functional groups and the phase composition of the prepared tobermorites respectively. The results of the morphology shows that the tobermorites possess irregular but spherical shaped grain with coated water films while the EDS shows the presence of Ca and Si with small amount of Al confirming tobermorite. The FT-IR indicates Ca–O–Si and Si–O–Si as main functional groups while the phase composition investigated by XRD indicate low intensity peaks of calcium silicate (CaSiO3). Resumen: En este estudio, las tobermoritas sintéticas se preparan utilizando biorresiduos (caparazón de caracol) y residuos municipales (vasos de contenedores) como precursores de cal y sílice, respectivamente. Se formularon seis composiciones discontinuas con una combinación variable de vidrio de cal sodada y ceniza de concha de caracol. Los cuerpos se sinterizaron a 950 °C durante un período de retención de 2 h en un horno de mufla eléctrico. Se utilizaron análisis como microscopía electrónica de barrido (SEM/EDS), espectroscopía infrarroja por transformada de Fourier (FT-IR), difractometría de rayos X (XRD) para evaluar la microestructura, los grupos funcionales y la composición de fase de las tobermoritas preparadas, respectivamente. Los resultados de la morfología muestran que las tobermoritas poseen un grano irregular pero esférico con películas de agua recubiertas, mientras que el EDS muestra la presencia de Ca y Si con una pequeña cantidad de Al que confirma la tobermorita. El FT-IR indica Ca-O-Si y Si-O-Si como grupos funcionales principales, mientras que la composición de fase investigada por XRD indica picos de baja intensidad de silicato de calcio (CaSiO3).
de Camargo Italo Leite, Lovo João Fiore Parreira, Erbereli Rogério
et al.
The development of photosensitive ceramic slurries for vat photopolymerization (stereolithography or digital light processing) has received much effort in recent years. However, many of these ceramic suspensions have high viscosity and they are suitable for use only on equipment, specialized in ceramic additive manufacturing. In this work, ceramic manufacturing using photocurable slurries was tested in a low-cost vat photopolymerization printer and in silicone moulds for UV-casting replication, with the latter approach still scarcely explored in the literature. Both processes were able to produce ceramic parts. The UV-casting replication was able to work with more viscous photocurable ceramic slurries and proved more suitable for the manufacturing of ceramic parts with larger cross-sections, providing pieces with improved flexural strength to those produced by additive manufacturing. This work presents the possibility of UV-casting photosensitive slurries to manufacture ceramics, an approach that could be easily adopted without high equipment costs.
Hiroyuki Kinoshita, Koya Sasaki, Kentaro Yasui
et al.
The effective reuse of waste glass fiber-reinforced plastic (GFRP) is desired. We previously produced porous ceramics by firing mixtures of crushed GFRP and clay in a reducing atmosphere and demonstrated their applicability as adsorbents for the removal of basic dyes from dyeing wastewater. However, the primary influencing factors and the dye adsorption mechanism have not been fully elucidated, and the adsorption of acidic and direct dyes has not been clarified. In this study, adsorption tests were conducted, and the effects of the firing atmosphere, specific surface area, type of dye, and individual components were comprehensively investigated. The results showed that reductively fired ceramics containing plastic carbide residue adsorbed basic dye very well but did not adsorb acidic dye well. The clay structure was the primary factor for the dye adsorption rather than the GFRP carbide. The mechanism for the basic dye adsorption appears to have been an increase in specific surface area due to the plastic carbide residue in the ceramic structure, which increased the ion exchange between the clay minerals and the dye. By adjusting the pH of the aqueous solution, the GFRP/clay ceramic also adsorbed considerable amounts of direct dye, so the mechanism was determined to be ion exchange with the calcium component of the glass fibers.