Clays are fundamental raw materials in the ceramics industry due to their plasticity, mineralogical composition, and thermal behavior. This study characterizes four clay samples from Bustos (Portugal), aiming to assess their suitability for ceramic applications through granulometric, geochemical, mineralogical, and technological assays, looking at aspects such as their plasticity and sintering behavior. A textural analysis of the samples revealed distinct granulometric profiles, being dominated by silty–clayey fractions and low amounts of coarse particles, indicating high plasticity potential. Three samples showed an alkaline pH (8.17–8.63), and one an acidic pH (5.11), which can significantly influence the rheology and firing behavior of the ceramic body. Samples had a predominance of phyllosilicate minerals, followed by quartz and magnetite–maghemite, and trace amounts of feldspars, anatase, bassanite, and siderite. In the clay fraction, smectite, illite, and kaolinite were identified. By combining classical analysis techniques with ceramic technology principles, this study contributes to the sustainable development of local ceramic industries, emphasizing the importance of characterizing natural raw materials for industrial applications. The plasticity tests showed strong workability in two samples, which exhibited high values of plasticity and moldability, making them suitable for shaping processes in ceramic production. Also, sintering behavior tests revealed that the same clays exhibited good densification during firing, with relatively low shrinkage.
Nicolás Gabriel Orsetti, Domingo Pérez-Coll, Gabriel Lorenzo
et al.
Ti-doped lithium zirconate (LZTO) sheets were successfully made by aqueous tape casting, by starting from an innovative colloidal synthesis route and optimizing the colloidal processing parameters. Zeta potential and particles size measurements, together with rheological characterization, were performed to adjust the slip composition. Then, the suspension with 1.0 wt% of ammonium polyacrylate dispersant (APA) and solid loading of 31 vol.% resulted in flat and flexible sheets, thinner than 450 µm, by adding 20 wt% of acrylic binder emulsion. After annealing at 1150 °C/15 h, LZTO sheets densified up to 85.5 %, presented a microstructure with grains of 6.4 µm in diameter, and exhibited electrical conductivity values in the order of 10−7, 10−6 and 10−5 S·cm−1 at 350, 450 and 600 °C, respectively. Besides, XRD phase analysis revealed monoclinic Li2ZrO3 and minor ZrO2 impurities originated from Li2O volatilization during sintering, but no sign of TiO2 segregation, indicating the formation of Li2Zr1-XTiXO3 solid solution.
One-dimensional tantalum carbide (TaC) nanorods are considered promising candidates for high-temperature electromagnetic wave (EMW) absorption because of their intrinsically high electrical conductivity and exceptional thermal stability. However, conventional synthesis approaches typically yield products with low quality and poor efficiency, limiting their practical applicability. Here, we report the rapid and scalable synthesis of high-quality TaC nanorods via a molten salt-assisted carbothermal reduction strategy integrated with microwave heating. The formation of well-defined one-dimensional TaC nanorods was achieved within 20 min at 1300 °C by precisely tuning the precursor composition (Ta2O5 : C : NaCl : Ni = 1 : 8 : 2 : 0.08). The resulting TaC nanorods exhibit notable EMW absorption properties, with a maximum effective absorption bandwidth (EABmax) of 3.0 GHz at a simulated thickness of 1.0 mm and a minimum reflection loss (RLmin) of −30.5 dB. Off-axis electron holography reveals pronounced charge accumulation at the Ta2O5 shell/TaC core interface, indicative of interfacial polarization effects. Furthermore, radar scattering cross-section (RCS) simulations demonstrate substantial attenuation of the backscattered signal from a perfect electric conductor (PEC) substrate coated with the TaC layer, with the strongest electromagnetic energy dissipation observed at a coating thickness of 1.0 mm. These results underscore the viability of microwave-assisted synthesis as an efficient and sustainable route for producing high-performance TaC nanorods for EMW absorption applications under extreme thermal conditions.
Hydrogen produced from renewable energy sources is a valuable energy carrier for linking growing renewable electricity generation with the hard-to-abate sectors, such as cement, steel, glass, chemical, and ceramics industries. In this context, this paper presents a new model of hydrogen production based on solar photovoltaics and wind energy with application to a real-world ceramics factory. For this task, a novel multipurpose profit-maximizing model is implemented using GAMS. The developed model explores hydrogen production with multiple value streams that enable technical and economical informed decisions under specific scenarios. Our results show that it is profitable to sell the hydrogen produced to the gas grid rather than using it for self-consumption for low-gas-price scenarios. On the other hand, when the price of gas is significantly high, it is more profitable to use as much hydrogen as possible for self-consumption to supply the factory and reduce the internal use of natural gas. The role of electricity self-consumption has proven to be key for the project’s profitability as, without this revenue stream, the project would not be profitable in any analysed scenario.
Enrico Storti, Patricia Kaiser, Marc Neumann
et al.
In this work, refractory components based on alumina were produced by binder jetting using a large-scale 3D printer. The formulation contained several particle fractions up to a grain size of 3 mm, equal to the printer resolution. The binder system contained fine dead burnt magnesia, milled citric acid and reactive alumina, which were added to the aggregate mixture to create the powder bed. Deionized water was deposited from the printer's nozzles and triggered the binding reaction between the magnesia and citric acid. After 24 h, the printed samples were removed from the powder bed, dried and sintered at 1600 °C for 5 h. Reactive alumina contributed to the in situ creation of magnesium aluminate spinel at high temperature. The samples were characterized in terms of Young's modulus of elasticity, bending and compressive strength in 2 directions (parallel and perpendicular to the printing direction). The broken parts were used to investigate physical properties such as the open porosity and bulk density. The microstructure was studied by means of computed tomography. Finally, powder samples were used to determine the phase composition at different stages of production by means of XRD.
In this work, nanocrystalline high-entropy ceramics (HECs) were prepared by the combination of combustion synthesis and ultra-high pressure sintering. The prepared high-entropy (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 ceramic powder had the average grain size of 11 nm and displayed the disordered defective fluorite structure. The HECs sintered under ultra-high pressure showed the defective fluorite structure, whereas the control samples fabricated by pressureless sintering showed the ordered pyrochlore structure. The HECs sintered under pressure of 10 GPa possessed much smaller grain size than that obtained by pressureless sintering. In particular, the grain size of ceramics sintered under 10 GPa at 600 °C was not significantly larger than that of raw powder and its Vickers hardness was 11.9 GPa. Ultra-high pressure sintering could remarkably increase the density of ceramics and restrain the growth of grains. The plastic deformation under ultra-high pressure was believed as the main densification mechanism for the grain refinement and performance improvement.
In the research field of energy storage dielectrics, the “responsivity” parameter, defined as the recyclable/recoverable energy density per unit electric field, has become critically important for a comprehensive evaluation of the energy storage capability of a dielectric. In this work, high recyclable energy density and responsivity, i.e., Wrec = 161.1 J·cm–3 and ξ = 373.8 J·(kV·m2)–1, have been simultaneously achieved in a prototype perovskite dielectric, BaTiO3, which is integrated on Si at 500 ℃ in the form of a submicron thick film. This ferroelectric film features a multi-scale polar structure consisting of ferroelectric grains with different orientations and inner-grain ferroelastic domains. A LaNiO3 buffer layer is used to induce a {001} textured, columnar nanograin microstructure, while an elevated deposition temperature promotes lateral growth of the nanograins (in-plane diameter increases from ~10–20 nm at lower temperatures to ~30 nm). These preferably oriented and periodically regulated nanograins have resulted in a small remnant polarization and a delayed polarization saturation in the film’s P–E behavior, leading to a high recyclable energy density. Meanwhile, an improved polarizability/dielectric constant of the BaTiO3 film has produced a much larger maximum polarization than those deposited at lower temperatures at the same electric field, leading to a record-breaking responsivity for this simple perovskite.
MXene-based absorbers have shown promising application prospects because of their sophisticated structural design and clever material composites. However, the intrinsic MXene materials themselves have not achieved significant breakthroughs in microwave absorption (MA) performance. Therefore, the development of novel and efficient pure MXene absorbing materials is imperative to address inherent mismatches in electromagnetic parameters, highlighting the urgent need in this area. Here, a straightforward strategy involving etching time modulation is proposed to customize the electromagnetic wave (EMW) absorption properties of delaminated Mo2CTx MXene. The impact of varying etching degrees on the EMW absorption capabilities of Mo2CTx MXenes was systematically investigated through controlled etching durations of Mo2Ga2C MAX phase. Among them, the sample etched for 12 h achieved an effective absorption bandwidth (EAB) of 4.4 GHz at an ultrathin thickness of 1.3 mm, and the strongest reflection loss (RL) value was as high as −60.7 dB when the sample etching time was increased to 24 h. The improvement in absorbing performance was attributed to the dielectric loss and polarization process induced by terminal functional groups and surface-rich defects, which optimized impedance matching. This work establishes that intrinsic Mo2CTx MXene materials with superior absorbing properties outperform traditional pure MXenes, providing a strong basis for advancing Mo-based MXene absorptive materials.
Ceramic-coated graphite powders are considered as effective raw materials to fabricate three-dimensional continuous ceramic skeleton-reinforced graphite matrix composites which can overcome their inherent poor densification and improve their mechanical and antioxidation properties. However, the morphology and thickness regulation of ceramic coatings on graphite particles are still a great challenge. Herein, SiC-coated graphite (graphite@SiC) powders were prepared by nitriding combustion synthesis using Si and graphited mesocarbon microbead (MCMB) as raw powders with polytetrafluoroethylene (PTFE) as a promoter. The effects of the PTFE content and the Si/MCMB molar ratio on the phase composition and coating morphology were investigated. The phase transition and microstructure evolution of a combustion synthesis (CS) process were revealed by a gas-released quenching experiment. When the Si/MCMB molar ratio was 1 : 3 and the PTFE content was 10 wt%, the thickness of the SiC coating synthesized under 2 MPa N2 reached 1.14 μm. The corresponding sintered graphite@SiC composite had relative density of 99.2% and flexural strength of 231 MPa, accompanied by a significant improvement in high-temperature antioxidation properties. The as-synthesized graphite@SiC powders with good sinterability and antioxidation properties show great promise for applications in the nuclear industry and other extreme fields.
Abstract In an attempt to improve the effective utilization of solid waste generated in the steel industry and reduce the production cost of glass ceramics, glass ceramics were prepared from blast furnace slag as the main raw material. The effects of SiO2/CaO molar ratio on the viscosity, structure, and properties of the as-prepared CaO–MgO–Al2O3–SiO2 (CMAS) blast furnace slag glass ceramics were investigated by viscometry, X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and physicochemical property measurements. The results showed that with decreasing SiO2/CaO ratio, the viscosity and degree of polymerization of molten glass significantly decreased, and the main crystalline phase transformed from single diopside to a combination of augite and gehlenite phases, which affected the physicochemical properties of the glass ceramics. The glass ceramic sample with a density of 2.78 g/cm3 exhibited the best comprehensive performance: bending strength of 182.86 MPa, microhardness of 7.34 GPa, acid resistance of 95.21%, and alkali resistance of 98.43%. The various characterization results proved that the prepared glass ceramics could be potentially used for several industrial applications.
Although the economic value of glass products and its importance to the Saudi National Economy is vast, not much information is available about the current state of the art of the industry. Likewise little information is available about the geography, potential sites for mining sand as well as the evaluation of sand quality. This paper attempts to bridge this gap by presenting a feasibility study of fabricating normal glass and glass ceramics from Saudi Arabia’s domestically available raw materials. It discusses the current status of glass industry in Saudi Arabia and the Middle East region. It also gives a brief explanation about the sand topography in Saudi Arabia. In order to determine the feasibility of fabricating glass using these raw materials, experimental data on the fabrication of normal glass and glass-ceramics from indigenously available raw materials was obtained and reported as part of the findings of this paper Firstly, normal transparent glass were able to be fabricated without any apparent large defects using sand collected from Ar-Rayis region in Saudi Arabia. Four nano-sized crystallization catalysts, namely VC, WC, TiC and Y2O3, were added to the constituents of the glass in 3 wt.%. For VC, the crystallization process was limited. The glass ceramics of WC consisted of multi-dimensional edges crystals which covered all the matrix. Gray crystalline whiskers were obtained by addition of TiC. The Y2O3- glass ceramics consisted of multi-directionally rosette crystals. Finally, the microhardness values of the added crystallization catalysts glass ceramics were obtained and found to be much higher compared to normal glass. The results show that glass of high quality can be produced specifically for Ar—Rayis region which would be of interest to researchers, glass industry personnel and potential investors
Michelle Pereira Babisk, L. F. Amaral, Larissa da Silva Ribeiro
et al.
Abstract In the aluminum industry, the initial operation comprises the production of its oxide, Al2O3 (alumina) from ores, mainly the bauxite. The Bayer process is, in practice, the only used to produce alumina generating a huge amount of hazardous waste known as red mud. Among the proposed alternatives to consider red mud a useful by-product, the incorporation into clay ceramics allows large quantities to be reutilized as construction products. Several research works investigated this alternative but were limited to single clay incorporation without specific application in building construction products. In the present work the possibility of producing bricks and roofing tiles for building construction with plain red mud and incorporations separately, in two different clays, with low and high plasticity, was for the first time investigated. Both red mud and clays were characterized. Corresponding ceramics fired at 850, 950 and 1050°C were evaluated for their technological properties. The results indicated that plain red mud fired at any of these temperatures might be used as bricks according to the Brazilian standards. It could also be used for roofing tiles production when fired at 1050°C. Application in bricks for building construction and a preliminary environmental assessment were for the first time presented.
Abstract The need for alternative building materials and the call for a cleaner environment has led to the recycling of waste materials in the construction industry. This study investigated the use of crushed glass and polypropylene (plastic) granules in two sets of fired clay bricks. These wastes were added to bricks at 1, 2, 3, 4, and 5% proportions, the bricks were fired to 800 °C in an electric operated kiln for about four hours. The glass infused bricks were designated as T1, T2, T3, T4, and T5, while that of plastics were designated as P1, P2, P3, P4 and P5 respectively. The control burnt brick is without any waste. Water Absorption, Shrinkage, mechanical strength tests were carried out on each brick. Scanning Electron Microscopy (SEM) was used to investigate the microstructural characteristics of each brick. The mechanical test result showed that the control has a value of 6.15 N/mm2, which is above the 3.5 N/mm2 recommended for clay bricks by standards. The highest value for bricks containing glass was from sample T5 at 11.02 N/mm2, while that of the sample containing plastic was P1 at 4.02 N/mm2. All the bricks have a water absorption rate less than the recommended 18 %. The SEM result revealed micro-cracks and voids that aided the structural efficiency of each brick types. The study concluded that glass can be added to burnt bricks at 5% replacement, while plastic waste should not exceed 3% in burnt bricks.
Abstract The dielectric capacitors with excellent energy storage characteristics, high power density and temperature stability are strongly desired in modern pulse power system and electronic industry. Thus, BKNAS-xPbO glass-ceramics were designed and prepared. Free oxygen in the glass phase which weakens the glass network structure can be adsorbed by trace Pb2+, thus improving the breakdown strength (BDS) of BKNAS glass-ceramics. Extremely high BDS (~2089 kV/cm) and excellent energy storage density (~17.62 J/cm3) were achieved in 0.6 mol% PbO doped BKNAS glass-ceramics. Moreover, the permittivity variance of BKNAS-0.6PbO glass-ceramics was less than 4.39% in the ultrawide temperature range (−80–300 °C), suggesting excellent temperature stability. The single layer capacitor made by BKNAS-0.6PbO glass-ceramics also exhibited excellent charge-discharge performance, in which the underdamped discharge power density reached 133.69 MW/cm3 as well as the overdamped discharge power density reached 146.89 MW/cm3 with ultrashort discharge time (
Kaolin clay is an inexpensive and abundant material with potential for use as a low-dielectric-constant ceramic; however, the natural metallic oxides the clay contains hinder such applications. In this study, kaolin clay ceramics with excellent physical and dielectric properties were synthesized using kaolin clay as the raw material by chemical cleaning and sintering. Characterization of the resulting samples showed that the sulfuric acid treatment has a significant influence on the metallic oxide content and dielectric properties of the kaolin clay ceramics. When the kaolin clay raw material was treated with sulfuric acid three times, the dielectric constant decreased from 5.12 to 3.75 and the Vickers hardness increased from 946 to 1,214 kg/mm2 relative to the ceramic prepared from the untreated clay. Therefore, these ceramics exhibit significant potential for use in the microelectronics industry.
Nowadays, the disposal of industrial wastes is an ablaze issue worldwide, especially those containing hazardous materials. Lead silicate glass waste (LSG) produced during lead crystal glass manufacturing, which contains about 30% of toxic lead compounds, belongs to this category. This work aims to adopt an innovative clean method to convert this waste into novel advanced ceramic materials via an environmental friendly method. Chromia Cr2O3 and hematite Fe2O3 ceramics with different content (0, 5, 10, 15%) are added separately to the solid wastes of LSG recovered from national crystal glass industry to obtain various ceramics/LSG composites by pressureless sintering methods. Different properties of the produced composites are evaluated in terms of phase's identification and microstructural features. Optical properties in terms of absorbance, reflectance, band gap (Eg), refractive index (n) and photoluminescence (PL) are investigated. Magnetic and electrical properties are inclusively studied. Results indicated that, an addition of chromia and hematite as well as increasing their content to 15% has enhanced the microstructural features, optical, electrical and magnetic properties of the obtained composites. Cr2O3/LSG composites are considered as promising optical and electrical materials. However, Fe2O3/LSG composites showed the highest optical and magnetic properties. They are strongly recommended in optoelectronic and magneto-optical applications.
Abstract Glass-ceramic is widely used in optics and other areas because of its good physical and mechanical properties. However, the accompanying hard and difficult to machine characteristic brings great challenges to the commonly used grinding in industry. Previous researches on the removal mechanism of glass-ceramic are basically traditional low-speed scratch and low-speed grinding, ignoring the effect of the wheel speed on surface/subsurface damage. In this study, the effects of the wheel speed on the surface morphology, surface roughness, and subsurface damage of Zerodur glass-ceramics were studied at different wheel speeds based on a multi-step grinding process. Experimental and analytical results showed that increasing wheel speed can restrain the occurrence and development of brittle fractures due to the effects of strain rate and grinding temperature, resulting in fewer and smaller micro-pits and micro-cracks, and thus more signs of plastic flow are observed. In addition, the effects of wheel speed on surface roughness under the semi-finishing grinding stage are not as clearly defined as on that under the rough and finishing grinding stages. The smeared layers on the ground surface, which are related to the compound effects of the grinding temperature and semi-finishing grinding conditions, are recognized as the major contributor to the contradictory surface roughness results. Furthermore, the effect of wheel speed can prevent crack from nucleating and propagating, and then leads to a smaller depth of subsurface damage. Accordingly, there is a general trend toward subsurface damage depth with the increase of undeformed chip thickness, regardless of the grinding conditions. In a word, higher wheel speeds are easier to achieve ductile removal mode and conversely, the glass-ceramic is more prone to a brittle removal mode. The research is expected to provide guidance for grinding-induced damage control and the engineering application in high precision optical parts of glass-ceramic.
The results of a study of the anodic bonding parameters of transparent glass-ceramics based on lithium aluminosilicates which are promising as structural materials of MEMS and MOEMS sensors are presented. A comparison of the optical transmittance of these materials and classical for MEMS industry glasses has been carried out. The glass-ceramics electrical conductivity in a wide temperature range has been measured. The procedure of hermetic sealing of glass-ceramics by the anodic bonding at temperatures of 150 – 250 °C has been worked out. A prototype of glass-ceramic atomic cell has been fabricated.