Hasil untuk "Clay industries. Ceramics. Glass"

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.

Ye Zhang, Yue-hua Hu, Li Wang et al.

Abstract Lithium is one of the most important raw materials for the production of glass, ceramics, nuclear materials, pharmaceuticals, and batteries. Almost 80% of total land-based lithium reserves globally are salt-lake brines. Therefore, lithium should be extracted from salt-lake brines to meet the demand of various industries for lithium resources. Several approaches for lithium extraction have been developed in the past few decades, such as precipitation, ion exchange, adsorption, solvent extraction, and electrolysis. Among these methods, precipitation is the earliest studied and utilized in industrial plants. Furthermore, it has several advantages, such as low cost, green principle, and easy industrialization. This paper reviews the precipitation technology for lithium extraction and the relative mechanism proposed in literature to identify its important parameters. Precipitant dosage, pH value, temperature, and particle size of precipitate are important factors in the process. Economic viability and green principle of various methods are discussed, and potential technologies are suggested. Novel magnesium precipitants appear to be a prospective technology for lithium extraction from brines with high Mg/Li mass ratios. Magnesium precipitation technology also shows great potential in the comprehensive utilization of lithium and magnesium resources. Various precipitation approaches for lithium extraction from brines and perspectives for further investigation are proposed.

B. Srikanth, R. Goutham, R. Narayan et al.

Takuhiro Sasadaira, Naoto Tanibata, Hayami Takeda et al.

Chloride-based Li2FeCl4 has emerged as a promising candidate high-voltage, highly deformable cathode material for all-solid-state lithium-ion batteries. However, further enhancement of Li-ion conductivity is required for practical application. In this study, we synthesized Br-substituted Li2FeCl3.8Br0.2 and examined how partial anion substitution influences both the crystal structure and Li-ion conductivity. X-ray diffraction confirmed that a single-phase cubic framework was retained and that the lattice constant remained unchanged despite Br incorporation. As a result of AC impedance measurements, the ionic conductivity was confirmed to increase approximately twofold, from 2.0 × 10−5 S/cm for the pristine material to 4.0 × 10−5 S/cm for the Br-substituted sample. In an effort to uncover the underlying mechanism of this enhancement, first-principles calculations (Density Functional Theory) combined with genetic algorithm – driven structural optimization were performed. The calculations indicated that Br substitution promoted a more disordered occupancy of Li ions across the sites along the conduction pathways. These results demonstrate that targeted anion substitution effectively tunes the Li-site energy landscape and controls Li-ion conductivity in chloride cathode materials.

Lei Zhang, Linglei Kong, Weining Lei et al.

J. Leicher, A. Giese, C. Wieland

The decarbonization of industrial process heat is one of the bigger challenges of the global energy transition. Process heating accounts for about 20% of final energy demand in Germany, and the situation is similar in other industrialized nations around the globe. Process heating is indispensable in the manufacturing processes of products and materials encountered every day, ranging from food, beverages, paper and textiles, to metals, ceramics, glass and cement. At the same time, process heating is also responsible for significant greenhouse gas emissions, as it is heavily dependent on fossil fuels such as natural gas and coal. Thus, process heating needs to be decarbonized. This review article explores the challenges of decarbonizing industrial process heat and then discusses two of the most promising options, the use of electric heating technologies and the substitution of fossil fuels with low-carbon hydrogen, in more detail. Both energy carriers have their specific benefits and drawbacks that have to be considered in the context of industrial decarbonization, but also in terms of necessary energy infrastructures. The focus is on high-temperature process heat (>400 °C) in energy-intensive basic materials industries, with examples from the metal and glass industries. Given the heterogeneity of industrial process heating, both electricity and hydrogen will likely be the most prominent energy carriers for decarbonized high-temperature process heat, each with their respective advantages and disadvantages.

Peter Lenk, Peter van de Rotten, Ed Forwood

In this paper we will discuss a challenging, iconic, heritage, refurbishment project – Channel 4’s headquarters building located in London, England. The building was originally designed by Richard Rogers and Partners in collaboration with Arup, RFR and was executed in 1994 by Eiffel under a sub-contract package with Permasteelisa. We will methodically outline the procedures that were followed to assess and restore this ageing, iconic cable net façade where, in an almost unprecedented way, the face glass is used structurally to support the dead load of the panels below to create a chain of suspended glass panes. After approximately 25 years of service Arup was called back to provide advice to the client following a glass breakage incident.  This triggered a detailed condition survey which concluded that a project refurbishment was overdue.  Arup then provided further studies to inform strategic options as to how to best refurbish the façade.  This advice led to the appointment of Octatube to provide Pre-Construction Services Agreement (PCSA) support to assist the façade appraisal and to carry out design, material testing, calculation and to provide critical construction advice, and then lead to Ocatatube’s appointment to fully refurbish the iconic façade.

I.L. Snetkov, K.V. Sidorenko, O.V. Palashov et al.

Magneto-optical and thermo-optical characteristics of transparent Tb2Ti2O7 ceramics were investigated. The dependence of the index of refraction on the wavelength in the 0.29–2 μm range, the wavelength and temperature dependence of the Verdet constant, as well as the dependence of thermally induced depolarization on laser radiation power were measured. The value of the Verdet constant in Tb2Ti2O7 surpasses that in Tb3Ga5O12 by more than 1.68 times. The thermo-optical characteristic Qeff was estimated to be (1.8–3.7)∙10−8 1/K, which is record small compared to Qeff of the known magneto-optical materials. The small value of Qeff makes Tb2Ti2O7 a highly promising magneto-optical material for Faraday isolators and rotators for high average power lasers.

Xingxing Xiao, Saad Arif, Jinxue Ding et al.

Benefiting from molten salts as reaction media, molten salt synthesis (MSS) offers advantages such as control of local reaction conditions to tailor material characteristics, the production of uniform and homogeneous crystallites, as well as reduced energy consumption and emissions. In this study, we successfully synthesized regular polyhedral La-substituted CaTiO3 with an orthorhombic perovskite structure under molten salt conditions, utilizing a NaCl–KCl eutectic mixture at 1073 K for 6 h. The phase compositions of the prepared samples were determined through powder X-ray diffraction (XRD), and their morphologies were characterized via scanning electron microscopy (SEM). Our investigation of the thermoelectric properties reveals that the substitution of La3+ ions significantly enhances electrical conductivity and simultaneously introducing defects that substantially reduce lattice thermal conductivity. We achieved a maximum thermoelectric figure of merit (ZT) of approximately 0.27 at about 1200 K for the sample with a nominal composition of Ca0.8La0.2TiO3. This study is intended as a reference to experimentalists working in MSS for synthesizing CaTiO3-based ceramics and discloses the transport properties of La-doped CaTiO3-based ceramics.

Maria Daghmehchi, Chiara Coletti, Dong Hyeok Moon et al.

A. N. Guerreiro, I. Costa, Antonio B. Vale et al.

The oxides of group 14 have been widely used in numerous applications in glass, ceramics, optics, pharmaceuticals, and food industries and semiconductors, photovoltaics, thermoelectrics, sensors, and energy storage, namely, batteries. Herein, we simulate and experimentally determine by scanning kelvin probe (SKP) the work functions of three oxides, SiO2, SiO, and SnO2, which were found to be very similar. Electrical properties such as electronic band structure, electron localization function, and carrier mobility were also simulated for the three crystalline oxides, amorphous SiO, and surfaces. The most exciting results were obtained for SiO and seem to show Poole–Frankel emissions or trap-assisted tunneling and propagation of surface plasmon polariton (SPP) with nucleation of solitons on the surface of the Aluminum. These phenomena and proposed models may also describe other oxide-metal heterojunctions and plasmonic and metamaterials devices. The SiO2 was demonstrated to be a stable insulator interacting less with the metals composing the cell than SnO2 and much less than SiO, configuring a typical Cu/SiO2/Al cell potential well. Its surface charge carrier mobility is small, as expected for an insulator. The highest charge carrier mobility at the lowest conduction band energy is the SnO2’s and the most symmetrical the SiO’s with a similar number of electron holes at the conduction and valence bands, respectively. The SnO2 shows it may perform as an n-type semiconductor.

Yongbin Hua, Jae Su Yu, Li Li

Novel rare-earth (RE; e.g., europium (Eu3+), samarium (Sm3+), and praseodymium (Pr3+)) and transition metal (TM4+; e.g., manganese (Mn4+)) ion single-/co-doped double-perovskite Ca2InTaO6 (CITO) phosphors were prepared and investigated with respect to their crystal structure and photoluminescence (PL) properties. Among them, the CITO:Eu3+ phosphors were found to exhibit an ultra-high internal PL quantum yield (89.1%) and good thermal stability (78.7% at 423 K relative to the initial value at 303 K). As such, the corresponding packaged white light-emitting diode (LED) was able to display a remarkable color rendering index (CRI; = 91.51@10 mA). Besides, the potential in applications of anti-counterfeiting fields and a novel LED structure based on flexible phosphor-converted films was also studied. Moreover, due to their different thermal quenching, trivalent lanthanide (Ln3+)/Mn4+ co-doped CITO phosphors were designed for optical thermometry based on the luminescence intensity ratio (LIR) between different 4f transitions of various Ln3+ ions and 2Eg → 4A2g (Mn4+) transition. Particularly, the LIR between the 4G5/2 → 6H9/2 and 2Eg → 4A2g peaks of the CITO activated with 5 mol% Sm3+ and 0.3 mol% Mn4+ exhibited the most excellent relative sensitivity (Sr; = 3.80 %·K−1) with beneficial temperature uncertainty of 0.0648 K. Overall, these results are of significance to offer valuable databases for constructing multifunctional high-performance optical platforms using single-/co-doped double-perovskite tantalates.

Durda Ewa, Kruk Andrzej

Commercial La0.6Sr0.4Co0.2Fe0.8O3-δ powder was used for preparation of corresponding perovskite films on commercial Crofer 22 APU high chromium steel by pulsed laser deposition. The obtained films PLD1 and PLD2 with a thickness of 1.1 and 0.35 μm, respectively, were dense and homogeneous, with good adhesion to the polished surface. Oxidation studies of the samples were carried out in air at 800°C for 200h. The calculated parabolic rate constant kp after isothermal oxidation for the PLD1 sample was 4.10 × 10−14 g2cm−4s−1 and was approximately four times lower than the oxidation rate determined for the PLD2 sample. As a result of the oxidation process, in both cases, a thin oxide layer of chromia and Mn1.5Cr1.5O4 spinel was formed on the steel/film interface. In addition, small amounts of manganese-chromium spinel crystals were observed on the films’ surfaces. Values of the specific electrical resistance at 800 °C after 100 h of the experiment were 0.06 and 0.038W•cm2 for PLD1 and PLD2, respectively. The results indicate that the applied coatings meet the criteria set upon protective-conductive layers for interconnect materials, for the IT-SOFCs (intermediate-temperature solid oxide fuel cells) applications.

M. C. Gadioli, M. C. De Aguiar, F. W. H. Vidal et al.

Brazil is one of the largest producers of ornamental stones in the world. The state of Espírito Santo has considerable social and economic relevance in the production of ornamental stones, particularly in exportation and the jobs that are directly related to this industry. The objectives of this work were to evaluate the effect of the incorporation of ornamental stone waste on the physical and mechanical properties of red ceramic manufactured using clays and waste from the state of Espírito Santo, and to collaborate to regulate the use of this ornamental stone waste in the ceramic industry when manufacturing products. Ornamental stone wastes were incorporated into the ceramic mass in the following proportions: 0, 10, 20, 30, 40 and 50% by weight. In the elaborated compositions, specimens were prepared by extrusion and were fired at 1050 °C and 1100 °C. After firing, the physical and mechanical properties of the material were analyzed using density, water absorption, porosity, linear shrinkage and mechanical strength. The results indicated an improvement in the properties of the ceramics with the addition of the waste by mass for the two temperatures. Therefore, the lower temperature (1050 °C) can be used to sinter the materials produced whilst obtaining satisfactory results and saving electrical energy. Ornamental stone waste has very promising applications in the ceramic industry.

José Ramón Urquijo Goitia

Yang Liu, Kai Wilkner, Unoaku Victoria Unije et al.

Asymmetric oxygen transport membranes have been extensively studied revealing the importance of the support porosity. In this study, asymmetric membranes with vertically channelled pores were prepared from Ba0.5Sr0.5(Co0.8Fe0.2)0.97Zr0.03O3-δ (BSCF-Z) by phase inversion tape casting. The rate-limiting effects of the membrane layer thickness, the support structure, and the activation layers were thoroughly analysed. This entails comparing the permeation rate of the samples with the membrane layer on different sides of the channelled supports. Pore tortuosity and computed permeability were evaluated from 3D-X-ray computed tomography and compared to previously reported asymmetric membranes prepared by tape-casting and freeze-drying. Due to a lower pore tortuosity, the channelled supports have an advantage in gas transport over the tape cast and freeze cast supports. However, this is compensated by a thicker membrane layer (∼54 μm) resulting in similar performance compared to the thinner membrane layers (∼20 μm) with freeze cast and tape cast supports.

Jae-Hoon Ji, Sanghyun Yoon, Jung-Hyuk Koh

In this study, piezoelectric properties of 0.4Bi(Ni0.5Zr0.5)O3–0.6PbTiO3 (BNZ-PT) and 0.4Bi(Mg0.5Zr0.5)O3–0.6PbTiO3 (BMZ-PT) ceramics were investigated and compared with those of Pb(Zr,Ti)O3 in energy harvester applications. Their piezoelectric properties are comparable with those of Pb(Zr,Ti)O3 based materials, although they have lower lead contents. By optimizing the sintering temperature, the piezoelectric charge coefficients (d33) were improved to 438 and 351 pC/N for 0.4BNZ-0.6PT and 0.4BMZ-0.6PT, respectively, whereas the piezoelectric voltage coefficients (g33) were improved to 25.02 × 10−3∙V∙m/N and 28.37 × 10−3∙V∙m/N for 0.4BNZ-0.6PT and 0.4BMZ-0.6PT, respectively. The generated energies were estimated by measuring the generated output voltages. Generated energy densities of 1.67 and 1.01 mJ/cm3 were obtained from 0.4BNZ-0.6PT and 0.4BMZ-0.6PT, respectively. The optimum sintering conditions were found by observing the changes in the piezoelectric constant, dielectric constant, and density as a function of the sintering temperature.

Yu-Chieh Fei, Liu-Gu Chen, Chao-Kuang Kuo et al.

With the emerging development of bioactive materials, mesoporous bioactive glasses (MBGs) are regarded as potential candidates for bone and tissue engineering due to its high surface area. In the present work, spray pyrolyzed MBGs doped with Strontium (Sr), an ion which promotes osteoblast bone-forming activity, were prepared. While the phase information, particle morphology, porous structure, and specific surface area were characterized by X-ray diffractometer, scanning electron microscope, transmission electron microscope, and nitrogen adsorption/desorption isotherm, respectively. In addition, in vitro bioactivity was examined following Kokubo’s protocol while the osteoblast activity was examined by alkaline phosphatase (ALP) assays. Finally, the results indicate that MBG specimens with optimal Sr dopant can enhance bioactivity and osteoblast activity and corresponded mechanisms were discussed.

Alexander Held, Georg Puchas, Ferdinand Müller et al.

As a feasibility study, a direct ink writing process using a conventional FDM-printer and colloidal C–SiC pastes was developed. The pastes have a low content of organic additives, which enables the omission of a pyrolysis step, i.e. the green parts can undergo the liquid silicon infiltration process directly after drying.The rheological behavior of the pastes was investigated regarding their viscosity, thixotropy and yield point. By analyzing important effects of 3D-printing, such as bridging and the possibility to print overhangs, the printability was determined. The near-net shape ability of the process was studied by comparing the dimensions after each processing step.The microstructure of the samples showed no detectable microstructural anomalies in this interface area. The phase analysis of the samples showed no residual carbon in the SiSiC parts. Printed SiSiC parts reached flexural strengths of 190 ​MPa, a hardness of 15.7 ​GPa and a Young’s Modulus of 246 ​GPa.

M. Jakab, M. Enisz-Bódogh, K. Kovacs et al.

Bioactive glass-ceramic coated 3D scaffolds with proper mechanical properties were fabricated. The base material of the scaffold is bovine bone, which appears mainly as a waste of the meat processing industry. After pre-treatment, different glass-ceramic mixtures were deposited onto the surface of these bones by infiltration in a vacuum chamber to form a smooth layer having a thickness of about 20 ?m. This coating has a beneficial effect both on the hardness and bending strength, and has bioactive properties to promote the colonization of bone-forming cells. Therefore, a scaffold that provides mechanical support and is biodegradable, was achieved with the bovine bone - glass-ceramics composites. Structure and properties of the composite scaffolds were tested by imaging methods (SEM, LM, CT), chemical and phase composition (EDS, XRD), strength, hardness and specific surface area measurements. In vitro cytotoxicity and cell adsorption were tested using colon adenocarcinoma tumour cells.