Hasil untuk "Clay industries. Ceramics. Glass"

Monica Ferraris, Stefano De la Pierre, Valentina Casalegno et al.

Silicon carbide fiber-reinforced composites (SiC/SiC) are leading candidates to replace zirconium-based alloys as cladding in light water reactors (LWR), owing to their exceptional oxidation resistance and mechanical performance under accident conditions.However, pressure-less joining methods compatible with the extreme chemical and thermal environment of LWRs remain a major technological hurdle.This work evaluates two promising joining materials—Mo-wrap (a MoSi₂/Si composite) and SAY (a silica–alumina–yttria glass-ceramic)—under simulated LWR conditions.Joining was performed using both conventional furnaces and laser-assisted techniques.Joint integrity and microstructure were assessed by SEM/EDS and X-ray computed tomography. Hydrothermal stability was evaluated in static and flowing-water (loop) autoclaves up to 30 days at 330 °C and 150–155 bar.Mo-wrap joints showed partial degradation due to silicon dissolution, while SAY joints retained good structural integrity in static tests but suffered phase-selective corrosion under flowing conditions, with keivite emerging as the most stable crystalline phase.Laser-processed amorphous SAY joints exhibited improved corrosion resistance, though still limited under prolonged exposure.These findings advance the understanding of joining performance in nuclear-relevant environments and support the development of accident-tolerant fuel cladding.

Afia Yasmin, Bristy Biswas, Md. Lutfor Rahman et al.

CoFe2O4 was synthesized at 150 °C, 180 °C, and 210 °C temperatures using hydrothermal method to find the effect on its structural, magnetic, electric, and optical properties. The saturation magnetization, coercivity and magnetic anisotropy was found using Vibrating Sample Magnetometer (VSM), ranging from 50.36 to 53.66 emu/g. XRD (X-ray Diffraction Analysis) and SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared Spectroscopy) was used for structural analysis verifying the spinel ferrite structure with a single phase. The crystalline size and lattice strain was found using Size-Strain Plot (SSP) and Debye-Scherrer (D-S) method which proved that as the synthesis temperature increased, the crystallite size also increased. The crystalline size ranges from 39.40 to 82.24 nm as observed by XRD. SEM analysis found the crystal size range to be from 9 to 12 nm. It was found that the optimum temperature to synthesize cobalt ferrite nanoparticles are at 180 °C for sample H2 with a crystal size of 82.24 nm and band gap energy of 2.60 eV. The Ms value was determined to be 50.36 emu/g for H2 sample with Rs value of 0.31.

Mengru Li, Zhenya Zhang, Xianyi Zeng et al.

T. Ibn-Mohammed, N. Bhanot, A.H. Mohammed et al.

Angelica Cardoza, Henry A. Colorado

This study shows an alkaline activated cement (AAC), also known as geopolymer, made from red brick waste with partial addition of Ordinary Portland Cement (OPC). This is a sustainable material since incorporates waste from the brick industry to make cements, therefore increasing the materials circularity and this reducing pollution. The material was cured at room temperature. The brick residue was activated with sodium hydroxide and sodium silicate in aqueous solution to form the hybrid cement. Several mixtures were made with different amounts of waste and proportions of alkaline activator. The mechanical properties of the materials were studied to determine their feasibility to be used in the construction sector. Three contents of OPC were used: 10, 20, and 30 wt%, which were added to improve the mechanical behavior and post-curing time. The activated hybrid cement was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), compression, and flexural tests. The main results show that the addition of OPC to the brick derived AAC produces an increased compressive strength of 106 MPa when 30 wt% OPC was added, a very significant result since the control sample found was 33 MPa in compression strength, an improvement for more than 3 times. The data were corroborated by statistical analysis.

Priya G. Nakade, D. Bhatkhande, Manik Deosarkar et al.

Accessing safe drinking water in India faces a mounting challenge due to deteriorating water quality from industrial pollution and excessive groundwater extraction, leading to increased chemical impurities like fluoride affecting 66 million people across 20 states. Fluoride contamination, arising from natural sources like volcanic activity and mineral weathering, is compounded by industrial discharge from semiconductor, metal, glass, and fertilizer industries. Prolonged exposure to fluoride-laden water poses health risks, causing dental, skeletal, and non-skeletal fluorosis. To address these risks, the World Health Organization (WHO) set the acceptable fluoride limit in drinking water at 1.5 mg/l. Despite various available technologies like coagulation and membrane processes, adsorption remains the most cost-effective method, especially for domestic use. Materials such as alumina, zeolite, clay, coal, and ceramics have been studied as fluoride adsorbents. In present study, laterite, bauxite, hematite, and calcite minerals rich in iron, aluminum, silica, and calcium were examined for fluoride ion adsorption at 7 pH and room temperature. Laterite displayed superior adsorption capacity compared to other minerals. Parameters like stirring speed, adsorbent size, and thermal treatment were investigated for their impact on laterite’s adsorption capacity. Raw laterite was successfully modified by loading it with copper oxide using a copper sulphate solution, significantly elevating its adsorption capacity from 0.26 to 1.905 mg/g, an eight-fold increase. Freundlich isotherm analysis confirmed multilayer adsorption facilitated by electrostatic forces. Isotherm study validates that surface-modified laterite is a robust adsorbent for fluoride removal at neutral pH and room temperature, presenting a promising solution for water treatment needs.

P. Lemougna, A. Ismailov, Erkki Levanen et al.

P. Tihomirovs, A. Korjakins

Recycling glass waste obtained from different industries is an issue in today’s economy. One of the ways of recycling is to produce lightweight ceramic by applying glass waste, clay, and gasifier as raw materials. The present research has been devoted to the evaluation of the influences of different clays extracted from two Latvian quarries (Lielauce un Samini) on the properties of lightweight ceramics. The main criteria of applicated clay as raw materials for producing lightweight ceramic are the following: saturation of SiO2 should be a maximum of 70% and Al2O3 minimum of 12%. The aim of the present research was to elaborate a composition for producing glass ceramic from glass waste with minimum energy consumption with a gasifier. The most important properties of the final product are thermal conductivity, compression strength, volume density, size, granulometry, and pore distribution. Two parameters of them, compression strength and volume density have been tested and analysed in the present research framework. Burning time is one more important additional parameter, which has been considered evaluating the properties of the final product. The obtained volume density is in the range of 226.75 kg/m3 to 475.78 kg/m3 depending on the composition.

G. Mahran

This study aims to treat Nepheline syenite for the glass and ceramics industries. Nepheline syenite has many uses in the glass and ceramics industries. It uses to lower the melting point and fuel savings. In the glass industry, nepheline syenite acts as a source of alumina, which increases resistance to scratching and breaking, improves thermal endurance, and increases chemical durability. A series of processing methods such as dry magnetic separation, flotation, and leaching methods were used respectively to treat nepheline syenite ore. In this paper, the results of combined magnetic, flotation, and leaching Processes of the cleaner concentrate having 0.1% Fe2O3 and 23.25% Al2O3.

Zhilin Tian, Keyu Ming, Liya Zheng et al.

Rare earth (RE) silicate is one of the most promising environmental barrier coatings for silicon-based ceramics in gas turbine engines. However, calcium–magnesium–alumina–silicate (CMAS) corrosion becomes much more serious and is the critical challenge for RE silicate with the increasing operating temperature. Therefore, it is quite urgent to clarify the mechanism of high-temperature CMAS-induced degradation of RE silicate at relatively high temperatures. Herein, the interaction between RE2SiO5 and CMAS up to 1500 ℃ was investigated by a novel high-temperature in-situ observation method. High temperature promotes the growth of the main reaction product (Ca2RE8(SiO4)6O2) fast along the [001] direction, and the precipitation of short and horizontally distributed Ca2RE8(SiO4)6O2 grains was accelerated during the cooling process. The increased temperature increases the solubility of RE elements, decreases the viscosity of CMAS, and thus elevates the corrosion reaction rate, making RE2SiO5 fast interaction with CMAS and less affected by RE element species.

Haoyu Zhang, Shuang Gao, Haitao Guan et al.

<p>Photocatalytic CO₂ reduction to valuable chemical compounds could be a promising approach for carbon-neutral practice. In this work, a simple and robust thermal decomposition process was developed with ammonium carbonate ((NH₄)₂CO₃) as both precipitation agent and sacrificial template to produce fine Nb₂O₅ nanoparticles with the rich existence of surface hydroxyl (–OH) groups. It was found by density functional theory (DFT) calculations and experiments that the rich existence of the surface –OH groups enhanced the adsorption of both reactants (CO₂ and H₂O molecules) for the photocatalytic CO₂ reduction on these fine Nb₂O₅ nanoparticles, and the highly selective conversion of CO₂ to the high-value chemical compound of ethylene (C₂H₄, ~68 μmol·g⁻¹·h⁻¹ with ~100% product selectivity) was achieved under simulated solar illumination without usage of any sacrificial agents or noble metal cocatalysts. This synthesis process may also be readily applied as a surface engineering method to enrich the existence of the surface –OH groups on various metal oxide-based photocatalysts for a broad range of technical applications.</p>

Adeolu Adediran, P. Lemougna, J. Yliniemi et al.

Abstract Concerns about the management of glass wool waste, approximately 800,000 tons of which are generated annually in Europe, are increasing. To test the feasibility of incorporating this waste into ceramic materials, this study examined the reuse of glass wool as a fluxing agent in the production of clay- and waste-based building ceramics. Commercial kaolin clay and two industrial residues, namely quartz-feldspar sand (QFS) and copper slag (CS), were selected as the precursors. Six compositions were prepared, three samples containing glass wool and three counterparts without glass wool, and then sintered at 750, 850, and 950 °C. The materials and prepared ceramics were characterized by employing x-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive x-ray spectroscopy (EDS), differential scanning calorimetry (DSC), water absorption, apparent density, and compressive and flexural strength tests. Interestingly, the results indicated that incorporating 10 wt% of glass wool into the QFS, CS, and kaolin mixtures created ceramics with better physical, mechanical, and microstructural properties. This was ascribed to the glass wool melting reactions observed from approximately 700 °C. The QFS samples with glass wool and sintered at 950 °C achieved compressive strength values as high as 117 MPa and water absorption percentages as low as 2%. However, the fluxing effect of glass wool was less significant in the CS- and kaolin-based ceramics, likely due to differences in their chemical composition, mineralogy, and particle-size distribution. The results of this study emphasize the reuse potential of glass wool and other waste streams in building ceramics and could contribute to improving the management of glass wool waste in line with social sustainability objectives.

P. Tihomirovs, A. Korjakins

Porous ceramics as sustainable material can become and, in some industries, already are used to achieve environmental applications considering their properties. Research on important composition properties helps to identify the best product to be used in construction industry with a priority of a minimum number of raw materials and simplest and energy-efficient technology during production process. The elaborated research identifies compositions with glass waste, clay, and soot with minimum volume density within the range of chosen product line. Water absorption, thermal conductivity, and compressive strength were researched to identify possible applications of elaborated material in construction industry.

P. O. Odewole

In this study, samples of glass-ceramics foam were obtained from granite dust-clay-maize cob composite and chemical additives at low temperature. Effects of the addition of maize cob as the pore-forming agent as well as the chemical additives on the performance properties of the samples of the glass-ceramics foam were investigated. The result of the prepared glass-ceramics foam showed water absorption, apparent porosity, bulk density, compressive strength and thermal conductivity of 25.6–46.7%, 43.5–75%, 1.45–1.9 g/cm3, 0.7–9.7 MPa and 0.11–0.53 W/m.K. respectively. The mechanical and thermo-physical properties as well as microstructural properties of the glass-ceramics foam synthesized in this study provide a feasible indicator that the material can be used in promoting green and sustainable buildings.

Mario Linz, Jörg Exner, Tobias Nazarenus et al.

Repair instead of discard is going to be crucial in the vision of a green future, therefore we propose the powder aerosol deposition (PAD) as a promising technique to reprocess ceramic coatings at room temperature. Alumina coated copper substrates with an artificial imperfection are manufactured in a first step. In a second step, the repair of this imperfection is carried out using two different PAD apparatuses: first, a conventional PAD apparatus with a moving substrate holder and a converging slit nozzle and second, a miniaturized μPAD apparatus with a fixed substrate holder and a circular de-Laval nozzle. The different film profiles are studied using a laser scanning confocal microscope. Cross-sectional images to investigate the microstructure are taken by a scanning electron microscope. Finally, samples of both PAD apparatuses are exposed to an oxidizing atmosphere at 400 °C proving the gas-tightness as a further quality feature of the repair coating.

Thorsten Weimar, Christian Hammer

The method of fibre optic strain measurement based on Rayleigh signal analysis enables the detection of the deformation behaviour of laminated glass and the modelling of its load-bearing characteristics. The measurement system is already calibrated for glass surfaces by studies of Institute of Structural Design at Universität Siegen. In addition to discretely measuring systems, such as strain gauges, the distributed measurement system is particularly suitable for determining the interlaminar shear modulus. The sensors used in bending tests on laminated glass supplement the deformation measurements taken with strain gauges and inductive displacement sensors. The study describes the results of the shear modulus of viscoelastic interlayers made of polyvinyl butyral and provides the basis to define and evaluate a model for the finite element analysis.

Noresah Fauzi, I. Ibrahim, S. E. Arshad

Ceramics are the oldest art objects ever produced by humans since prehistoric times. Ceramics are made from clay and will change character when exposed to high temperatures above 1200 degrees celsius. Ceramic product is covered with a layer of glass which is a glaze and has a high resistance to temperature or heat. This research aims to document the production of glaze color systematically using various types of stone in Sabah such as Sungai Moyog stone, Lombong Mamut stone, and stone in Sports Complex, Ranau on the surface of the specimen body produced using by kaolin. In addition, this research also aims to identify the response of experimental samples using a mixture of different percentages using the formula Triaxial Line Blend on the surface of kaolin involving aspects of the material, type of combustion, and decoration techniques. The production of glaze color using natural materials which is a Sungai Moyog stone, Lombong Mamut stone, and Sports Complex stone found around Ranau and Kota Kinabalu, Sabah is an innovation in the production of color sourced from natural materials as well as efforts to develop the ceramic industry in Malaysia. It is more to the production of natural materials that have undergone the production process to produce a new glaze color. Preliminary studies using samples from color agents which are Sungai Moyog stone, Lombong Mamut stone, and Ranau Sports Complex stone were conducted experimentally. The research includes the preparation and formulation of glaze using the material until it successfully produces color pigments according to the temperature reaction and the type of combustion that has been implemented. This research also aims to study the suitability of glaze color on the surface of ceramic products such as kaolin. In conclusion, through this research, we will better understand the processes and ways how to produce glaze color in the ceramic industry by using natural materials found in the environment. Through this research as well, it is possible to identify the minerals present in the experimental materials that influence the reaction in the production of ceramic glaze color.

Siham Oummadi, Benoit Nait-Ali, Arnaud Alzina et al.

The evolution of shrinkage and mass during drying of kaolin and alumina green bodies was characterized. Standard practise uses a position sensor with simultaneous mass measurement. In this work an optical method was developed to follow shrinkage in two orthogonal directions. Green body samples were made by pressing of ceramic pastes. Results have been compared through the well known Bigot curves which show two distinct stages. First a linear shrinkage with the evaporated water loss is observed. Then in the second stage with further water loss, negligible dimension changes occur. For each material, the overall shrinkage values are identical in the two directions parallel to the pressing axis, but higher in the pressing direction. This difference is related to the shaping method yielding a preferential orientation of grains. Anisotropy in shrinkage is more significant for kaolin with tabular shaped grains compared to the more isometric grains of alumina.

Jun Wang, Valérie Schölch, Oliver Görke et al.

Fei Li, Xiao Huang, Ji-Xuan Liu et al.

Abstract Ultra-high temperature ceramics (UHTCs) are considered as a family of nonmetallic and inorganic materials that have melting point over 3000 °C. Chemically, nearly all UHTCs are borides, carbides, and nitrides of early transition metals (e.g., Zr, Hf, Nb, Ta). Within the last two decades, except for the great achievements in the densification, microstructure tailoring, and mechanical property improvements of UHTCs, many methods have been established for the preparation of porous UHTCs, aiming to develop high-temperature resistant, sintering resistant, and lightweight materials that will withstand temperatures as high as 2000 °C for long periods of time. Amongst the synthesis methods for porous UHTCs, sol-gel methods enable the preparation of porous UHTCs with pore sizes from 1 to 500 urn and porosity within the range of 60%-95% at relatively low temperature. In this article, we review the currently available sol-gel methods for the preparation of porous UHTCs. Templating, foaming, and solvent evaporation methods are described and compared in terms of processing-microstructure relations. The properties and high temperature resistance of sol-gel derived porous UHTCs are discussed. Finally, directions to future investigations on the processing and applications of porous UHTCs are proposed.