Hasil untuk "Clay industries. Ceramics. Glass"

M. Tokita

The spark plasma sintering (SPS) method is of great interest to the powder and powder metallurgy industry and material researchers of academia for both product manufacturing and advanced material research and development. Today in Japan, a number of SPS products for different industries have already been realized. Today’s fifth-generation SPS systems are capable of producing parts of increasing size, offering improved functionality, reproducibility, productivity, and cost. For instance, pure nano-Tungsten Carbide WC powder (no additives) is fully densified with a nano-grain-sized structure for glass lens application in the optics industry. The SPS is now moving from scientific academia and/or R&D proto-type materials level usage to practical industry use product stage utilizing in the field of electronics, automotive, mold and die, cutting tools, fine ceramics, clean energy, biomaterials industries, and others. This paper reviews and introduces the peculiar phenomenon of SPS and the progress of SPS technology, method, development of SPS systems, and its industrial product applications.

Shuye Zhang, Xinyue Li, Fugang Lu et al.

Femtosecond laser welding, a novel technique for material joining, faces challenges such as stringent pre-welding requirements and low joint strength when directly welding ceramics. In this study, we addressed the issues associated with the direct welding of yttria-stabilized zirconia (YSZ) and sapphire by first depositing a nanometer-thick Ti layer on the ceramic surface, followed by femtosecond laser welding. Notably, we observed for the first time that femtosecond laser pulses induced the formation of a honeycomb structure at the interface, forming a YSZ/sapphire micro-welding joint characterized by a continuous structure, a honeycomb structure, and Ti-rich phases. This specific joint distribution significantly enhanced the interface transition and improved the joint strength. Under conditions of 8 W laser power, scanning speed of 50 mm/s, and pulse frequency of 200 kHz, the micro-welding joint exhibited optimal interface performance, achieving a maximum shear strength of approximately 79 MPa. Through calculations of the temperature distribution of the interface and the surface energy of the crystal, we conclude that the honeycomb structure arises from the Ti layer, the temperature gradient distribution, and the tendency of sapphire to melt along directions with lower surface energy. The honeycomb structure effectively enriched the transition between the micro-welding interface and the substrate. The new findings of this study offer valuable insights and potential pathways for the reliable and efficient welding of advanced ceramics.

Fei Hao, Xin Liu, Jinyao Zhu et al.

BaTiO3 has been investigated nearly several decades due to its excellent ferroelectric and dielectric properties. However, the property evolution of BaTiO3 with a particle size of sub-10 nm is still unclear because of the difficulty during the fabrication and characterization. Here, a series of BaTiO3 nanoparticles with the average particle sizes of 2.8, 4.5 and 8.1 nm are achieved, and their phase structure, ferroelectric and dielectric properties are skillfully characterized. With the particle size decreasing from 8.1 to 2.8 nm, the nanoparticles show a declining non-centrosymmetry, nonlinear response, ferroelectricity and dielectric constant. Nevertheless, the 2.8 nm BaTiO3 nanoparticles still possess observable second harmonic generation, ferroelectric polarization switching behavior and butterfly loop, showing weak but distinguishable ferroelectricity. This research depicts a detailed ferroelectric and dielectric property evolution in sub-10 nm BaTiO3 nanoparticles, which provides theoretical basis and promising candidate for the future ferroelectric applications.

Ondřej Jankovský, Petr Lodňánek, Anna-Marie Lauermannová et al.

In response to the global demand for CO2 emissions reduction, Portland cement (PC) replacement with more eco-friendly materials has been focused on in material studies. One of the studied alternatives is magnesium oxychloride cement (MOC), which offers excellent mechanical properties and lower production temperatures. The ecological impact of MOC alone is significant, but if we incorporate waste material as a filler replacement in MOC composites, we can decrease overall emissions even more. In this paper, we focused on the development of an eco-friendly material with a safely incorporated ladle furnace slag (SL). Firstly, the SL was characterized by numerous analytical methods (XRF, XRD, SEM, EDS, STA-MS) to attain knowledge about its elemental and phase composition. In the following step, MOC composite materials with SL used as a silica sand partial replacement were prepared by casting. Such prepared materials were then characterized by XRF, XRD, SEM, EDS, and MIP. Furthermore, their structural and mechanical properties were assessed. Based on the obtained results, an optimized composition of mixtures was used for 3D printing to demonstrate the suitability of this material for this purpose. Finally, X-ray computed micro-tomography imaging was used to study the quality of printed cubes, in particular porosity and the amount of macroscopic defects. This paper presents an innovative approach in which waste SL from steel production can replace silica sand filler in significant quantities, demonstrating that such a designed material is suitable for additive manufacturing.

Qihang Ren, Yang Zhang, Haoliang Tao et al.

Achieving thermal cycle stability is an imperative challenge for the successful commercialization of solid oxide cell (SOC) technology. Ruddlesden‒Popper (R‒P) oxides, whose thermal expansion coefficient (TEC) is compatible with common electrolytes, are promising candidates for SOC applications. However, the two-dimensional conduction characteristic of R‒P oxides leads to insufficient catalytic activity, which hinders their performance. Here, we propose a win‒win strategy for self-assembly decoration by employing a one-pot method to address this issue. By using a single perovskite oxide (La0.4Sr0.6FeO3) to modify R‒P oxide (La0.8Sr1.2FeO4+δ), we enhanced the electrochemical performance without compromising the stability of the composite electrode. The strategic incorporation of a 10 mol% perovskite phase at 800 °C resulted in a significant 49% reduction in the polarization resistance (Rp), an impressive 86% increase in the maximum power density under power generation mode, and a notable 33% increase in the electrolysis current density under electrolysis mode. Furthermore, the perovskite-decorated R‒P oxide composite also exhibited high thermal and chemical stability, with negligible performance degradation observed under both thermal cycling and charge/discharge cycling conditions. Our results demonstrate that such dual-phase composites, which are simultaneously produced by a one-step process with outstanding catalytic activity and stability, can be considered an effective strategy for the advancement of SOCs.

Xinchi Zhou, Zhen Zhang, Xinyu Jiang et al.

Among various metal oxide nanomaterials, manganese oxides, which can exist in different structures and valence states, are considered highly promising anode materials for lithium-ion batteries (LIBs). However, conventional manganese oxides, such as MnO and MnO2, face significant challenges during cycling process. Specifically, poor electronic conductivity and large volume changes result in low specific capacity during high current charging and discharging, as well as poor fast-charging performance. This work presents an approach to synthesizing porous hexagonal Mn5O8 nanosheets via hydrothermal and annealing methods and applies them as anode materials for LIBs. The Mn5O8 nanomaterials exhibit a thin plate morphology, which effectively reduces the distance for ion/electron transmission and mitigates the phenomenon of volume expansion. Additionally, the large pore size of Mn5O8 results in abundant interlayer and intralayer defects, which further increase the rate of ion transmission. These unique characteristics enable Mn5O8 to demonstrate excellent electrochemical performance (938.7 mAh·g−1 after 100 cycles at 100 mA·g−1) and fast charging performance (675.7 mAh·g−1 after 1000 cycles at 3000 mA·g−1), suggesting that Mn5O8 nanosheets have the potential to be an ideal fast-charging anode material for LIBs.

Panupong Jaiban, Pimpilai Wannasut, Anucha Watcharapasorn

In this work, the influences of Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) addition on phase, microstructure, and thermoelectric properties of Ca3Co4O9 (CCO) were investigated. (1-x)CCO-(x)BCZT ceramics where x= 0, 0.003, 0.005, and 0.010 were fabricated successfully via a conventional solid-state sintering at 1,223 K for 24 h. The substitution of BCZT introduced the chemical defects ([Formula: see text], [Formula: see text], [Formula: see text]) in CCO ceramic, which increased charge carrier concentration and enhanced the electrical conductivity. The presence of Ca3Co2O6 phase and Co3+ improved the Seebeck coefficients of CCO ceramic. The thermal conductivity of CCO ceramic decreased when BCZT was added. The addition of BCZT at x = 0.010 promoted the highest thermoelectric power factor (PF~235 μW/mK2), and the highest figure of merit (ZT~0.5) at 800 K, which presents this ceramic an alternative p-type oxide thermoelectric for a high-temperature thermoelectric device.

Araceli De Pablos Martin, G. Gorni

Controlled crystallization of glasses is a broad research area within glass science in which researchers from academia and industry are both involved [...]

R. Hinterding, M. Wolf, M. Jakob et al.

The oxide materials Ca3Co4O9 and Na2Ca2Nb4O13 were combined in a new ceramic composite with promising synergistic thermoelectric properties. Both compounds show a plate-like crystal shape and similar aspect ratios but the matrix material Ca3Co4O9 with lateral sizes of less than 500 nm is about two orders of magnitude smaller. Uniaxial pressing of the mixed compound powders was used to produce porous ceramics after conventional sintering. Reactions between both compounds and their compositions were thoroughly investigated. In comparison to pure Ca3Co4O9, mixing with low amounts of Na2Ca2Nb4O13 proved to be beneficial for the overall thermoelectric properties. A maximum figure-of-merit of zT = 0.32 at 1073 K and therefore an improvement of about 19% was achieved by the ceramic composites.

J. McCloy, A. Goel

B. C. Jamalaiah, G. Viswanadha

Abstract Trivalent erbium ions doped Bi2O3-B2O3 transparent glass ceramics containing CaF2 were prepared and characterized through X -ray diffraction, scanning electron microscopy, Fourier transform infrared absorption, optical absorption, and near infrared emission for 1.53 μm fiber lasers. The glass ceramics obtained by applying thermal treatment at 575 °C for 5 h and 575 °C for 10 h contain Bi3B5O12 and CaF2 crystallites. The Judd-Ofelt theory was applied to evaluate various spectroscopic and laser characteristic properties. The NIR emission corresponding to the 4I13/2 → 4I15/2 (∼1.53 μm) transition was studied by exciting the samples at 514.5 nm laser radiation. The stimulated emission cross-sections of ∼1.53 μm luminescence were also obtained applying the Mc Cumber theory. The experimental results confirm that the transparent glass ceramic obtained at a thermal treatment of 575 °C for 10 h is more suitable to design fiber lasers for diverse applications in the fields of industry, medicine and scientific research.

T. Húlan, I. Štubňa, J. Ondruška et al.

Elastic properties of mixtures of illitic clay, thermal power plant fly ash (fluidized fly ash—FFA and pulverized fly ash—PFA), and grog were investigated during the heating and cooling stages of the firing. The grog part in the mixtures was replaced with 10, 20, 30, and 40 mass% of the fly ash, respectively. The temperature dependence of Young’s modulus was derived using the dynamical thermomechanical analysis, in which dimensions and mass determined from thermogravimeric and thermodilatometric results were used. Flexural strength was measured at the room temperature using the three-point bending test. The following results were obtained: (1) Bulk density showed a decreasing trend up to 900 °C and a steep increase above 900 °C. During cooling, the bulk density slightly increased down to the room temperature. (2) Young’s modulus increased significantly during heating up to ~300 °C. Dehydroxylation was almost not reflected in Young’s modulus. At temperatures higher than 800 °C, Young’s modulus began to increase due to sintering. (3) During cooling, down to the glass transformation, Young’s modulus slightly increased and then began to slightly decrease due to microcracking between phases with different thermal expansion coefficients. (4) Around the β→α quartz transition, radial stresses on the quartz grain altered from compressive to tensile, creating microcracks. Below 560 °C, the radial stress remained tensile, and consequently, the microcracking around the quartz grains and a decreasing Young’s modulus continued. (5) With a lower amount of PFA and FFA, a higher Young’s modulus was reached after sintering. The final values of Young’s modulus, measured after firing, show a decreasing trend and depend linearly on the part of fly ash. (6) The flexural strength measured after firing decreased linearly with the amount of the fly ash for both mixtures.

A. Veber, Zhuorui Lu, M. Vermillac et al.

For years, scientists have been looking for different techniques to make glasses perfect: fully amorphous and ideally homogeneous. Meanwhile, recent advances in the development of particle-containing glasses (PCG), defined in this paper as glass-ceramics, glasses doped with metallic nanoparticles, and phase-separated glasses show that these “imperfect” glasses can result in better optical materials if particles of desired chemistry, size, and shape are present in the glass. It has been shown that PCGs can be used for the fabrication of nanostructured fibers—a novel class of media for fiber optics. These unique optical fibers are able to outperform their traditional glass counterparts in terms of available emission spectral range, quantum efficiency, non-linear properties, fabricated sensors sensitivity, and other parameters. Being rather special, nanostructured fibers require new, unconventional solutions on the materials used, fabrication, and characterization techniques, limiting the use of these novel materials. This work overviews practical aspects and progress in the fabrication and characterization methods of the particle-containing glasses with particular attention to nanostructured fibers made of these materials. A review of the recent achievements shows that current technologies allow producing high-optical quality PCG-fibers of different types, and the unique optical properties of these nanostructured fibers make them prospective for applications in lasers, optical communications, medicine, lighting, and other areas of science and industry.

Maria Friedrich, M. Kahle, J. Bliedtner et al.

Fangyi Huang, Hua Su, Yuanxun Li et al.

Abstract In this study, low-temperature fired CaMg1−x Li2x Si2O6 microwave dielectric ceramics were prepared via the traditional solid-state reaction method. In this process, 0.4 wt% Li2CO3-B2O3-SiO2-CaCO3-Al2O3 (LBSCA) glass was added as a sintering aid. The results showed that ceramics consisted of CaMgSi2O6 as the main phase. The second phases were CaSiO3 always existing and Li2SiO3 occurring at substitution content x > 0.05. Li+ substitution effectively lowered sintering temperature due to 0.4 wt% LBSCA and contributed to grain densification, and the most homogeneous morphology could be observed at x = 0.05. The effects of relative density, the second phase, and ionic polarizability on dielectric constant (εr) were investigated. The quality factor (Q × f) varied with packing fraction that concerned the second phase. Moreover, the temperature coefficient of the resonant frequency (τf) was influenced by MgO6 octahedral distortion and bond valence. Excellent dielectric properties of the CaMg1−x Li2x Si2O6 ceramic was exhibited at x = 0.05 with εr = 7.44, Q × f = 41,017 GHz (f = 15.1638 GHz), and τf = −59.3 ppm/°C when sintered at 900 °C. It had a good application prospect in the field of low-temperature co-fired ceramic (LTCC) substrate and devices.

Tales Gonçalves Avancini, M. T. Souza, A. P. N. de Oliveira et al.

Abstract Magnetite-based glass-ceramic is a special composite material composed by magnetic nanocrystals embedded in a vitreous matrix. In this work, it was developed magnetic glass-ceramics based on borosilicate glass wastes and, for the first time, by using iron-rich scale (a waste from the metallurgical industry). Different compositions were established with increasing scale contents (20, 30, 45 wt%). Raw materials were melted (1550 °C/4 h) and later cast in a preheated steel mold at 400 °C. Then, the obtained samples were heat-treated at 700 °C/ 30 min. The sample with 45 wt% scale also was heated at 800 °C and 900 °C/ 30 min, in order to promote more crystallization. The obtained glass-ceramics properties were investigated using X-ray diffraction (XRD), Raman spectroscopy, vibrating-sample magnetometer (VSM), Mossbauer spectroscopy and transmission electron microscopy (TEM). Magnetite nanocrystals (average size in the 40–64 nm range) in the glass-ceramics were evidenced by TEM images and Mossbauer spectrum. VSM analysis revealed that the obtained ferrimagnetic glass–ceramic with composition of 45 wt% scale annealed at 800 °C/ 30 min, improved the magnetic saturation (Ms), reaching 42 emu/g. Results indicated a great potential of this magnetic-based glass-ceramics for being applied in many applications, such as the biomedical engineering field, in magnetic devices, magnetic resonance imaging contrast agents, hyperthermia, waste sorbent, and microwave devices.

V. Savvilotidou, A. Kritikaki, A. Stratakis et al.

This study investigates an innovative approach for the valorization of specific wastes generated from the energy sector and the production of glass-ceramics. The wastes used were photovoltaic (P/V) glass, produced from the renewable energy sector, and lignite fly ash, produced from the conventional energy sector. The process first involved the production of glass after melting specific mixtures of wastes, namely (i) 70% P/V glass and 30% lignite fly ash, and (ii) 80% P/V glass and 20% lignite fly ash, at 1200 °C for 1 h as revealed by the use of a heating microscope. The results indicated that the P/V glass, as a sodium-potassium-rich inorganic waste, reduces energy requirements of the melting process. The produced glass was then used for the production of glass-ceramics. Dense and homogeneous glass-ceramics, exhibiting high chemical stability and no toxicity, were produced after controlled thermal treatment of glass at 800 °C. The mechanical (compressive strength, Vickers hardness) and physical (open porosity, bulk density and water absorption) properties of the produced glass-ceramics were evaluated. X-ray diffraction (XRD) and Energy Dispersive X-ray fluorescence (ED-XRF) were used for the characterization of the raw materials and the produced glass-ceramics. Scanning electron microscopy (SEM) provided further insights on the microstructure of the final products. The properties of the produced glass-ceramics, namely water absorption and compressive strength, render them suitable for applications in the construction industry. The waste valorization approach followed in this study is in line with the principles of circular economy.

Jinshan Lu, Yingde Li, Chuanming Zou et al.

N. L. Ferber, N. L. Ferber, N. L. Ferber et al.

Haitao Gao, Xianghua Liu, Jingqi Chen et al.