Search results for: composite ceramics

Authors: Aung Kyaw Moe, Lukin Evgeny Stepanovich, Popova Nelya Alexandrovna

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In this paper, the effect of the additive content in the Al₂O₃-TiO₂-MnO system on the sintering of composite ceramics based on corundum was studied. The samples were pressed by uniaxial semi-dry pressing under 100 MPa and sintered at 1500 °С and 1550 °С. The properties of composite ceramics for porosity and flexural strength were studied. When the amount of additives increases, the properties of composite ceramic samples are better than samples without additives.

Keywords: ceramic, composite material, sintering, corundum

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Authors: Jian Zheng, Jinfeng Yu, Xinhua Ni

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The limiting fracture stress predicting model of composite ceramics with symmetric triangle eutectic was established based on its special microscopic structure. The symmetric triangle eutectic is consisted of matrix, the strong constraint inter-phase and reinforced fiber inclusions which are 120 degrees uniform symmetrical distribution. Considering the conditions of the rupture of the cohesive bond between matrix and fibers in eutectic and the stress concentration effect at the fiber end, the intrinsic fracture stress of eutectic was obtained. Based on the biggest micro-damage strain in eutectic, defining the load function, the macro-damage fracture stress of symmetric triangle eutectic was determined by boundary conditions. Introducing the conception of critical zone, the theoretical limiting fracture stress forecasting model of composite ceramics was got, and the stress was related to the fiber size and fiber volume fraction in eutectic. The calculated results agreed with the experimental results in the literature.

Keywords: symmetric triangle eutectic, composite ceramics, limiting stress, intrinsic fracture stress

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Authors: Yih-Chien Chen, Yu-Cheng You

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The microwave dielectric properties of La2MoO6 ceramics were investigated with a view to their application in mobile communication. La2MoO6 ceramics were prepared by the conventional solid-state method with various sintering conditions. The X-ray diffraction peaks of La2MoO6 ceramic did not vary significantly with sintering conditions. The average grain size of La2MoO6 ceramics increased as the temperature and time of sintering increased. A maximum density of 5.67 g/cm3, a dielectric constants (εr) of 14.1, a quality factor (Q×f) of 68,000 GHz, and a temperature coefficient of resonant frequency (τf) of -56 ppm/℃ were obtained when La2MoO6 ceramics that were sintered at 1300 ℃ for 4h.

Keywords: ceramics, sintering, microwave dielectric properties, La2MoO6

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Authors: Ngo the Bach

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Vietnam is one of not many Asian countries that have a long-standing and famous tradition of pottery production. Vietnam is also one of three countries including China, Vietnam, and Japan developed strongly the export of ceramics to other countries. In recent decades, the studies of Vietnamese and foreign scholars on Vietnamese trade ceramics as well as Vietnamese foreign trade was initially recorded. The aim of this article is to introduce an overview of the findings situation and research results; the development of Vietnam ceramics and the Vietnamese history of maritime trade with Asian ceramics from the 14th century to the 17th century. Given that, the author systematized materials; carried out the synthetic and analysis for research results of Vietnamese and foreign researchers until now on Vietnamese export ceramics on the basis of the historical sources, archaeological findings discovered from relics in the tombs, relics of residence, relics of trading port inland, and the ancient shipwreck sank in the Asian countries.

Keywords: Vietnamese ceramics, trading, maritime, international

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Authors: Andrey A. Lipovskii, Alexey V. Redkov, Vyacheslav V. Rusan, Dmitry K. Tagantsev, Valentina V. Zhurikhina

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The presented research is related to the development of recently proposed technique of the formation of composite materials, like optical glass-ceramics, with predetermined structure and properties of the crystalline component. The technique is based on the control of the size and concentration of the crystalline grains using the phenomenon of glass-ceramics decrystallization (vitrification) induced by ion-exchange. This phenomenon was discovered and explained in the beginning of the 2000s, while related theoretical description was given in 2016 only. In general, the developed theory enables one to model the process and optimize the conditions of ion-exchange processing of glass-ceramics, which provide given properties of crystalline component, in particular, profile of the average size of the crystalline grains. The optimization is possible if one knows two dimensionless parameters of the theoretical model. One of them (β) is the value which is directly related to the solubility of crystalline component of the glass-ceramics in the glass matrix, and another (γ) is equal to the ratio of characteristic times of ion-exchange diffusion and crystalline grain dissolution. The presented study is dedicated to the development of experimental technique and simulation which allow determining these parameters. It is shown that these parameters can be deduced from the data on the space distributions of diffusant concentrations and average size of crystalline grains in the glass-ceramics samples subjected to ion-exchange treatment. Measurements at least at two temperatures and two processing times at each temperature are necessary. The composite material used was a silica-based glass-ceramics with crystalline grains of Li2OSiO2. Cubical samples of the glass-ceramics (6x6x6 mm3) underwent the ion exchange process in NaNO3 salt melt at 520 oC (for 16 and 48 h), 540 oC (for 8 and 24 h), 560 oC (for 4 and 12 h), and 580 oC (for 2 and 8 h). The ion exchange processing resulted in the glass-ceramics vitrification in the subsurface layers where ion-exchange diffusion took place. Slabs about 1 mm thick were cut from the central part of the samples and their big facets were polished. These slabs were used to find profiles of diffusant concentrations and average size of the crystalline grains. The concentration profiles were determined from refractive index profiles measured with Max-Zender interferometer, and profiles of the average size of the crystalline grains were determined with micro-Raman spectroscopy. Numerical simulation were based on the developed theoretical model of the glass-ceramics decrystallization induced by ion exchange. The simulation of the processes was carried out for different values of β and γ parameters under all above-mentioned ion exchange conditions. As a result, the temperature dependences of the parameters, which provided a reliable coincidence of the simulation and experimental data, were found. This ensured the adequate modeling of the process of the glass-ceramics decrystallization in 520-580 oC temperature interval. Developed approach provides a powerful tool for fine tuning of the glass-ceramics structure, namely, concentration and average size of crystalline grains.

Keywords: diffusion, glass-ceramics, ion exchange, vitrification

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Authors: Mohammad Farooq Wani

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Tribological studies on nano-sized ß-silicon nitride+5% BN were carried out in dry air at high temperatures to clarify the lack of consensus in the bibliographic data concerning the Tribological behavior of Si3N4 ceramics and effect of doped hexagonal boron nitride on coefficient of friction and wear coefficient at different loads and elevated temperatures. The composites were prepared via high energy mechanical milling and subsequent spark plasma sintering using Y2O3 and Al2O3 as sintering additives. After sintering, the average crystalline size of Si3N4 was observed to be 50 nm. Tribological tests were performed with temperature and Friction coefficients 0.16 to 1.183 and 0.54 to 0.71 were observed for Nano-sized ß-silicon nitride+5% BN composite under normal load of 10N-70 N and over high temperature range of 350 ºC-550 ºC respectively. Specific wear coefficients from 1.33x 10-4 mm3N-1m-1 to 4.42x 10-4 mm3N-1m-1 were observed for Nano-sized Si3N4 + 5% BN composite against Si3N4 ball as tribo-pair counterpart over high temperature range of 350 ºC-550 ºC while as under normal load of 10N to70N Specific wear coefficients of 6.91x 10-4 mm3N-1m-1 to 1.70x 10-4 were observed. The addition of BN to the Si3N4 composite resulted in a slight reduction of the friction coefficient and lower values of wear coefficient.

Keywords: ceramics, tribology, friction and wear, solid lubrication

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Authors: K. D. Mandal, Anil Kumar Mourya, Ankur Khare

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Ceramics of 0.6 CaCu3TiO12 – 0.2 Bi2/3Cu3TiO12 – 0.2 Y2/3Cu3TiO12 (i.e. 0.6CCTO-0.2BCTO-0.2 YCTO) were prepared via semi - wet route. The phase structure of the sample was identified by X-Ray diffraction. The micro structure of the sample was observed by SEM, which displays grains of different shapes having diameter in range of 2 µm–4 µm. We have studied the frequency and temperature dependence of permittivity and impedance of the compound with LCR Meter in the range of 100 Hz–1 MHz and 300–500 K. The material shows its highest dielectric constant (428000) at 100 Hz and 368 K. The material shows Debye–like relaxation and their dielectric constant are independent of frequency and temperature over a wide range. The sample shows two electrical responses in impedance formalism, indicating that there are two distinct contributions. We attribute them to grain and grain boundaries in the ceramic sample and explain the dielectric behaviors by Maxwell–Wagner relaxation arising at the interfaces between grain and their boundaries.

Keywords: complex perovskite, ceramics composite, impedance study, SEM

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Authors: Nattida Wannaruk, Wasawat Nakkiew

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This research aims to study the factors that affect the performance of green supply chain management in the Lampang ceramics industry. The data investigation of this research was questionnaires which were gathered from 20 factories in the Lampang ceramics industry. The research factors are divided into five major groups which are green design, green purchasing, green manufacturing, green logistics and reverse logistics. The questionnaire has consisted of four parts that related to factors green supply chain management and general information of the Lampang ceramics industry. Then, the data were analyzed using descriptive statistic and priority of each factor by using the analytic hierarchy process (AHP). The understanding of factors affecting the green supply chain management of Lampang ceramics industry was indicated in the summary result along with each factor weight. The result of this research could be contributed to the development of indicators or performance evaluation in the future.

Keywords: Lampang ceramics industry, green supply chain management, analysis hierarchy process (AHP), factors affecting

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Authors: Santiranjan Shannigrahi, Mohit Sharma, Ivan Tan Chee Kiang, Yong Anna Marie

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Polymer-ceramics composites are gaining importance due to their high specific strength, corrosion resistance, and high mechanical properties, as well as low cost. As a result, polymer composites are suitable for various industrial applications, like automobiles, aerospace, and biomedical areas. The present work comprises the development of polymer-ceramic composite films and is tested for the harsh environment including weatherability and UV barrier property. The polymer composite films are kept in weather chamber for a fixed period of time followed by tested for their physical, mechanical and chemical properties. The composite films are fabricated using compounding followed by hot pressing. UV-visible spectroscopy results reveal that the pure polymer polyethylene (PE) films are transparent in the visible range and do not absorb UV. However, polymer ceramic composite films start absorbing UV completely even at very low filler loading amount of 5 wt.%. The changes in tensile properties of the various composite films before and after UV illuminations for 40 hrs at 60 degC are analyzed. The tensile strength of neat PE film has been observed 8% reduction, whereas the remarkable increase in tensile strength has been observed (18% improvement for 10 wt. % filled composites films). The UV exposure leads to strengthen the crosslinking among PE polymer chains in the filled composite films, which contributes towards the incremented tensile strength properties.

Keywords: polymer ceramic composite, processing, harsh environment, mechanical properties

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Authors: T. Kuchukhidze, N. Jalagonia, T. Archuadze, G. Bokuchava

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The growing scientific-technological progress in modern civilization causes actuality of producing construction materials which can successfully work in conditions of high temperature, radiation, pressure, speed, and chemically aggressive environment. Such extreme conditions can withstand very few types of materials and among them, ceramic materials are in the first place. Corundum ceramics is the most useful material for creation of constructive nodes and products of various purposes for its low cost, easy accessibility to raw materials and good combination of physical-chemical properties. However, ceramic composite materials have one disadvantage; they are less plastics and have lower toughness. In order to increase the plasticity, the ceramics are reinforced by various dopants, that reduces the growth of the cracks. It is shown, that adding of even small amount of carbon fibers and carbon nanotubes (CNT) as reinforcing material significantly improves mechanical properties of the products, keeping at the same time advantages of alundum ceramics. Graphene in composite material acts in the same way as inorganic dopants (MgO, ZrO2, SiC and others) and performs the role of aluminum oxide inhibitor, as it creates shell, that gives possibility to reduce sintering temperature and at the same time it acts as damper, because scattering of a shock wave takes place on carbon structures. Application of different structural modification of carbon (graphene, nanotube and others) as reinforced material, gives possibility to create multi-purpose highly requested composite materials based on alundum ceramics. In the present work offers simplified technology for obtaining of aluminum oxide ceramics, reinforced with carbon nanostructures, during which chemical modification with doping carbon nanostructures will be implemented in the process of synthesis of final powdery composite – Alumina. In charge doping carbon nanostructures connected to matrix substance with C-O-Al bonds, that provide their homogeneous spatial distribution. In ceramic obtained as a result of consolidation of such powders carbon fragments equally distributed in the entire matrix of aluminum oxide, that cause increase of bending strength and crack-resistance. The proposed way to prepare the charge simplifies the technological process, decreases energy consumption, synthesis duration and therefore requires less financial expenses. In the implementation of this work, modern instrumental methods were used: electronic and optical microscopy, X-ray structural and granulometric analysis, UV, IR, and Raman spectroscopy.

Keywords: ceramic materials, α-Al₂O₃, carbon nanostructures, composites, characterization, hot-pressing

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Authors: Parveen Kumar, J. K. Juneja, Chandra Prakash, K. K. Raina

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A series of polycrystalline ferroelectric ceramics with compositional formula Ba0.80-xSmxPb0.20Ti0.90Zr0.10O3 with x varying from 0 to 0.01 in the steps of 0.0025 has been prepared by solid state reaction method. The dielectric constant and tangent loss was measured as a function of frequency from 100Hz to 1MHz at different temperatures (200-500oC). The electrical behavior was then investigated using complex impedance spectroscopy (CIS) technique. From the CIS study, it has been found that there is a contribution of both grain and grain boundary in the electrical behavior of such ceramics. Grain and grain boundary resistivity and capacitance were calculated at different temperature using CIS technique. The present paper is about the discussion of grain and grain boundary contribution towards the electrical properties of Sm modified BaTiO3 based ceramics at high temperature.

Keywords: grain, grain boundary, impedance, dielectric

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Authors: C. Busuioc, S. Jinga, E. Pavel

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Optical lithography is a key technique in the development of sub-5 nm patterns for the semiconductor industry. We have already reported that the best results obtained with respect to direct laser writing process on active media, such as glass-ceramics, are achieved only when the energy of the laser radiation is absorbed in discrete quantities. Further, we need to clarify the role of active centers concentration in silver nanocrystals natural generation, as well as in fluorescent rare-earth nanostructures formation. As a consequence, samples with different compositions were prepared. SEM, AFM, TEM and STEM investigations were employed in order to demonstrate that few nm width lines can be written on fluorescent photosensitive glass-ceramics, these being efficient absorbers. Moreover, we believe that the experimental data will lead to the best choice in terms of active centers amount, laser power and glass-ceramic matrix.

Keywords: glass-ceramics, 3D laser writing, optical disks, data storage

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Authors: Ruchika Bagga, Mauro Falconieri, Venu Gopal Achanta, José M. F. Ferreira, Ashutosh Goel, Gopi Sharma

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Mixed valence Eu-doped nanocrystalline NaAlSiO4/NaY9Si6O26 glass-ceramics have been prepared by controlled crystallization of melt quenched bulk glasses. XRD and SEM techniques were employed to characterize the crystallization process of the precursor glass and their resultant glass-ceramics. Photoluminescence spectroscopy was used to analyze the formation of divalent europium (Eu2+) from Eu3+ ions during high temperature synthesis under ambient atmosphere and is explained on the basis of optical basicity model. The observed luminescence properties of Eu: NaY9Si6O26 are compared with that of well explored Eu: β-PbF2 nanocrystals and their marked differences are discussed.

Keywords: rare earth, oxyfluoride glasses, nano-crystalline glass-ceramics, photoluminescence spectroscopy

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Authors: Kanta Maan Sangwan, Neetu Ahlawat, Rajender Singh Kundu

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BaZrTiO3 ceramics having high dielectric constant and low dielectric loss are interesting material for being used as commercial capacitor applications. BZT (BaZrTiO3) has attracted attentions for their many applications for the microwave technology as the doping of Zr4+ on Ti4+ has advantage to the stability of the system. In the present work, co-doping of Zr and V with BaTiO3 ceramics was synthesized by the conventional solid state reaction technique and sintered at 1200 K for 6 hours, and their structural and ferroelectric properties were studied. The XRD (x-ray diffraction) pattern of BZT (BaZrTiO3) ceramics shows that the crystalline sample is single phase tetragonal structure with P4mm space group. The result revealed that Zr ion enters the unit cell maintaining the perovskite structure of BZT ceramics and the impedance spectroscopy of the sample performed in selected frequency and temperature range.

Keywords: ferroelectric, impedance spectroscopy, space group, tetragonal

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Authors: Ala Abobakr Abdulhafidh Al-Dubai

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Biomaterials, specifically metals and ceramics, are indispensable components in the realm of medical science, shaping the landscape of implantology and prosthetics. This study delves into the intricate interplay between these materials and biological systems, aiming to scrutinize their suitability, performance, and biocompatibility. Employing a multi-faceted approach, a range of methodologies were meticulously employed to comprehensively characterize these biomaterials. Advanced material characterization techniques were paramount in this research, with scanning electron microscopy providing intricate insights into surface morphology, and X-ray diffraction unraveling the crystalline structures. These analyses were complemented by in vitro assessments, which gauged the biological response of cells to metals and ceramics, shedding light on their potential applications within the human body. A key facet of our investigation involved a comparative study, evaluating the corrosion resistance and osseointegration potential of both metals and ceramics. Through a series of experiments, we sought to understand how these biomaterials interacted with physiological environments, paving the way for informed decisions in medical applications

Keywords: metals, ceramics, biomaterials, biocompatibility, osseointegration

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Authors: Muhammad Habib, Xuefan Zhou, Lin Tang, Guoliang Xue, Fazli Akram, Dou Zhang

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Defect engineering approach is a well-established approach for the customization of functional properties of perovskite ceramics. In modern technology, the high multiferroic properties for elevated temperature applications are greatly demanding. In this work, the Bi-nonstoichiometric lead-free 0.67Biy-xSmxFeO3-0.33BaTiO3 ceramics (Sm-doped BF-BT for Bi-excess; y = 1.03 and Bi-deficient; y = 0.975 with x = 0.00, 0.04 and 0.08) were design for the high-temperature multiferroic property. Enhanced piezoelectric (d33  250 pC/N and d33* 350 pm/V) and magnetic properties (Mr  0.25 emu/g) with a high Curie temperature (TC  465 ℃) were obtained in the Bi-deficient pure BF-BT ceramics. With Sm-doping (x = 0.04), the TC decrease to 350 ℃ a significant improvement occurred in the d33* to 504 pm/V and 450 pm/V for Bi-excess and Bi-deficient compositions, respectively. The structural origin of the enhanced piezoelectric strain performance is related to the soft ferroelectric effect by Sm-doping and reversible phase transition from the short-range relaxor ferroelectric state to the long-range order under the applied electric field. However, a slight change occurs in the Mr 0.28 emu/g value with Sm-doping for Bi-deficient ceramics, whereas the Bi-excess ceramics shows completely paramagnetic behavior. Hence, the origin of high magnetic properties in the Bi-deficient BF-BT ceramics is mainly attributed to the proposed double exchange mechanism. We believe that this strategy will provide a new perspective for the development of lead-free multiferroic ceramics for high-temperature applications.

Keywords: BiFeO3-BaTiO3, lead-free piezoceramics, magnetic properties, defect engineering

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Authors: Ying-Chieh Lee, Huei-Jyun Shih, Ting-Yang Wang, Christian Pithan

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This study focuses on the synthesis and characterization of Ca₀.₆Sr₀.₄₋ₓBaₓZrO₃ (x = 0.01, 0.04, 0.07, and 0.10) ceramics prepared via the solid-state method and sintered at 1450 °C. The impact of Sr substitution by Ba at the A-site of the perovskite structure on crystalline properties and microwave dielectric performance was investigated. The experimental results show the formation of a single-phase structure, Ca₀.₆₁₂Sr₀.₃₈₈ZrO₃(CSZ), across the entire range of x values. It is evident that the Ca₀.₆Sr₀.₃₉Ba₀.₀₁ZrO₃ ceramics exhibit the highest sintering density and the lowest porosity. These ceramics exhibit impressive dielectric properties, including a high permittivity of 28.38, low dielectric loss of 4.0×10⁻⁴, and a Q factor value of 22988 at 9~10GHz. The research reveals that the influences of Sr substitution by Ba in enhancing the microwave dielectric properties of Ca₀.₆₁₂Sr₀.₃₈₈ZrO₃ ceramics and the impedance curves clearly showed effects on the electrical properties.

Keywords: NPO dielectric material, (Ca₀.₆Sr₀.₄)ZrO₃, microwave dielectric properties

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Authors: Christian C. Vaso, Rinlee Butch M. Cervera

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One of the most promising anode materials for solid oxide electrolysis cell (SOEC) application is the Sr-doped LaMnO₃ (LSM) which is known to have a high electronic conductivity but low ionic conductivity. To increase the ionic conductivity or diffusion of ions through the anode, Yttria-stabilized Zirconia (YSZ), which has good ionic conductivity, is proposed to be combined with LSM to create a composite electrode and to obtain a high mixed ionic and electronic conducting anode. In this study, composite of lanthanum strontium manganite and YSZ oxide, La_0.8Sr_0.2MnO₃/Zr_0.92Y_0.08O₂ (LSM/YSZ), with different wt.% compositions of LSM and YSZ were synthesized using solid-state reaction. The obtained prepared composite samples of 60, 50, and 40 wt.% LSM with remaining wt.% of 40, 50, and 60, respectively for YSZ were fully characterized for its microstructure by using powder X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and Scanning electron microscope/Energy dispersive spectroscopy (SEM/EDS) analyses. Surface morphology of the samples via SEM analysis revealed a well-sintered and densified pure LSM, while a more porous composite sample of LSM/YSZ was obtained. Electrochemical impedance measurements at intermediate temperature range (500-700 °C) of the synthesized samples were also performed which revealed that the 50 wt.% LSM with 50 wt.% YSZ (L50Y50) sample showed the highest total conductivity of 8.27x10^-1 S/cm at 600 ^oC with 0.22 eV activation energy.

Keywords: ceramics, microstructure, fuel cells, electrochemical impedance spectroscopy

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Authors: Ramovatar, Neeraj Panwar

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Lead free Ba₀.₉₈Ca₀.₀₂SnxTi₁₋ₓO₃ (x = 0.01 and 0.05 mole %) ferroelectric ceramics have been synthesized by the solid-state reaction method with sintering at 1400 °C for 2 h. The room temperature x-ray diffraction (XRD) patterns identified the tetragonal phase for x = 0.01 composition whereas co-existence of tetragonal and orthorhombic phases for x =0.05 composition. Raman spectroscopy results corroborated with the XRD results at room temperature. The maximum dielectric properties (ɛm ~ 8591, tanδ ~ 0.018) were obtained for the compound with x = 0.01 at 5 kHz. Further, the tetragonal to cubic (TC) transition temperature was observed at 122 °C and 102 °C for the ceramics with x =0.01 and x = 0.05, respectively. The temperature dependent P-E loops also revealed the existence of TC at these particular temperature values. The energy storage density (Ed) of both compounds was calculated from room temperature P – E loops at an applied electric field of 20 kV/cm. The maximum Ed ~ 224 kJ/m³ was achieved for the sample with x = 0.01 as compared to 164 kJ/m³ for the x =0.05 composition. The value of Ed is comparable to other BaTiO₃ based lead free ferroelectric systems. Impedance spectroscopy analysis exhibited the bulk and grain boundary contributions above 300 °C under the frequency range 100 Hz to 1 MHz. The above properties make these ceramics suitable for energy storage devices.

Keywords: dielectric properties, energy storage properties, impedance spectroscopy, lead free ceramics

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Authors: Venkatesan Sundaramoorthy

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The field of ceramics has undergone a remarkable transformation with the advent of additive manufacturing technologies. This comprehensive review explores the mechanical properties of additively manufactured ceramic components, focusing on key materials such as Alumina, Zirconia, and Silicon Carbide. The study delves into various authors' review technology into the various additive manufacturing techniques, including Stereolithography, Powder Bed Fusion, and Binder Jetting, highlighting their advantages and challenges. It provides a detailed analysis of the mechanical properties of these ceramics, offering insights into their hardness, strength, fracture toughness, and thermal conductivity. Factors affecting mechanical properties, such as microstructure and post-processing, are thoroughly examined. Recent advancements and future directions in 3D-printed ceramics are discussed, showcasing the potential for further optimization and innovation. This review underscores the profound implications of additive manufacturing for ceramics in industries such as aerospace, healthcare, and electronics, ushering in a new era of engineering and design possibilities for ceramic components.

Keywords: mechanical properties, additive manufacturing, ceramic materials, PBF

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Authors: N. Flores-Martinez, G. Franceschin, T. Gaudisson, J.-M. Greneche, R. Valenzuela-Monjaras, S. Ammar

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Tailoring bulk materials keeping their nanoscale properties is the daydream of material scientists. But especially in magnetism, this single desire can revolutionize our everyday life. Now, thanks to the methods of synthesis, based on the combination of colloidal chemistry (CC) to flash sintering (FS), customizing magnets becomes each time more 'easy', 'cheap' and 'clean'. Although by CC we can obtain straightway nanopowders with good magnetic featuring, like exchange bias (EB) phenomenon, it does not result so attractive for applications. Since a solid material is simple to manipulate and integrate in a device, many consolidation methods have been tested aiming to keep the nanopowders characteristics after consolidation. Unfortunately, the lack of structural crystalline arrangement and the grain growth worsen the magnetic properties. In this work, we exhibit, for the first-time author’s best knowledge, the EB in sintered ceramics, starting from CoFe₂O₄-core@CoO-shell NPs obtained by CC. Despite the fact that EB field is about 28 mT in ceramics and it is not yet considered for applications, this work opens an alternative in the permanent magnets fabrication through a FS method, the spark plasma sintering, starting from CC synthesized nanopowders.

Keywords: core-shell nanoparticles, exchange bias, nanostructured ceramics, spark plasma sintering

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Authors: Mohammad Shariq, Davinder Kaur

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A series of multiferroic (BiFeO3)1−x(PbTiO3)x [x= 0, 0.1, 0.2, 0.3, 0.4 and 0.5] solid solution ceramics were synthesised by conventional solid-state reaction method. Well crystalline phase has been optimized at sintering temperature of 950°C for 2 hours. X rays diffraction studies of these ceramics revealed the existence of a morphotropic phase boundary (MPB) region in this system, which exhibits co-existence of rhombohedral and tetragonal phase with a large tetragonality (c/a ratio) in the tetragonal phase region. The average grain size of samples was found to be between 1-1.5 µm. The M-H curve revealed the BiFeO3 (BFO) as antiferromanetic material whereas, induced weak ferromagnetism was observed for (BiFeO3)1−x(PbTiO3)x composites with x=0.1, 0.2, 0.3, 0.4 and 0.5 at temperature of 5 K. The results evidenced the destruction of a space-modulated spin structure in bulk materials, via substituent effects, releasing a latent magnetization locked within the cycloid. Relative to unmodified BiFeO3, modified BiFeO3-PbTiO3 -based ceramics revealed enhancement in the electric-field-induced polarization.

Keywords: BiFeO3)1−x(PbTiO3)x ceramic, multiferroic, SQUID, magnetic properties

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Authors: Roopam Gaur, K. Chandramani Singh, Radhapiyari Laishram

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In order to produce lead free piezoceramics with optimum piezoelectric and dielectric properties, KNN modified with Li+ (as an A site dopant) and Sb5+ (as a B site dopant) (K0.49Na0.49Li0.02) (Nb0.96Sb0.04) O3 (referred as KNLNS in this paper) have been synthesized using solid state reaction method and conventional sintering technique. The ceramics were sintered in the narrow range of 10500C-10900C for 2-3 hours to get precise information about sintering parameters. Detailed study of dependence of microstructural, dielectric and piezoelectric properties on sintering conditions was then carried out. The study suggests that the volatility of the highly hygroscopic KNN ceramics is not only sensitive to sintering temperatures but also to sintering durations. By merely reducing the sintering duration for a given sintering temperature we saw an increase in the density of the samples which was supported by the increase in dielectric constants of the ceramics. And since density directly or indirectly affects almost all the associated properties, other dielectric and piezoelectric properties were also enhanced as we approached towards the most suitable sintering temperature and duration combination.

Keywords: piezoelectric, dielectric, Li, Sb, KNN, conventional sintering

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Authors: Benchalak Muangmeesri

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The purpose of this paper is to discuss how to test the best control performance of a ceramics. Hydraulic press machine (HPM) is the most common shaping of advanced ceramic with products, dimensions, and ceramic products mainly from synthetic powders. A microcontroller can be achieved to control process and has set high standards in the shaping of raw materials in powder form. HPM was proposed to develop a position control system that linked to the embedded controller PIC16F877 via Proportional and Derivative (PD) controller. The model is performed using MATLAB/SIMULINK and the best control performance of an HPM. Finally, PD controller results, showing the best performance as it had the smallest overshoot and highest quality using a microcontroller control.

Keywords: ceramics, hydraulic press, microcontroller, PD controller

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Authors: S. Khardazi, H. Zaitouni, A. Neqali, S. Lyubchyk, D. Mezzane, M. Amjoud, E. Choukri, S. Lyubchyk, Z. Kutnjak

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In the present paper, structural, dielectric, ferroelectric, and energy storage properties of pure perovskite lead-free BCZT, BTSn, and BTSn-BCZT ferroelectric ceramics have been investigated. Rietveld refinement of XRD data confirms the coexistence of the rhombohedral and orthorhombic phases at room temperature in the composite BCZT–BTSn ceramic. Remarkably, an improved recoverable energy density of 137.86 mJ/cm³ and a high energy storage efficiency of 86.19 % at 80°C under a moderate applied electric field of 30 kV/cm were achieved in the designed BCZT–BTSn ceramic. Besides, the sample exhibits excellent thermal stability of the energy storage efficiency (less than 3%) in the temperature range of 70 to 130 °C under 30 kV/cm. Such results make the pb-free BCZT–BTSn ferroelectric ceramic a very promising potential matrix for energy storage capacitor applications.

Keywords: sol-gel, ferroelectrics, lead-free, perovskites, energy storage

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Authors: Andualem Belachew Workie

Abstract:

In a spray pyrolysis process, apatite-Wollastonite glass-ceramics (AW GC) were fabricated with the composition 8.29MgO_50.09-x CaO_34.46SiO2_7.16P2O5_xCaF₂, where x = 0, 0.54, and 5.24 (wt. %). Based on the results, it appears that the CaF2 addition lowers the glass transition temperature (Tg) and crystallization temperature (Tc) of the glasscomposition. In addition, AW GC's bioactivity increases as the soaking time in simulated body fluid (SBF) increases. Adding CaF₂ and varying sintering temperatures altered the density and linear shrinkage percentage of the samples. The formation of fluorapatite with needle-like microstructure and the formation of the wollastonite phase was enhanced with higher CaF2 content, while the growth of the whitlockite phase took place at a higher heat treatment temperature. Adding high CaF₂ content with high sintering temperatures to apatite Wollastonite glass-ceramic composition facilitates the formation of fluorapatite, which is crucial for denture glass-ceramics.

Keywords: apatite-wollastonite glass ceramics, bioactivity, hydroxyapatite, calcium fluoride

Procedia PDF Downloads 59

Authors: Bing-Jing Li, Sih-Yin Wang, Tse-Chun Yeh, Yuan-Bin Chen

Abstract:

Microwave dielectric ceramic materials of (Mg1-xNix)2(Ti0.95Sn0.05)O4 for x = 0.01, 0.03, 0.05, 0.07 and 0.09 were prepared and sintered at 1250–1400ºC. The microstructure and microwave dielectric properties of the ceramic materials were examined and measured. The observations shows that the content of Ni2+ ions has little effect on the crystal structure, dielectric constant, temperature coefficient of resonant frequency (τf) and sintering temperatures of the ceramics. However, the quality values (Q×f) are greatly improved due to the addition of Ni2+ ions. The present study showed that the ceramic material prepared for x = 0.05 and sintered at 1325ºC had the best Q×f value of 392,000 GHz, about 23% improvement compared with that of Mg2(Ti0.95Sn0.05)O4.

Keywords: (Mg1-xNix)2(Ti0.95Sn0.05)O4, microwave dielectric ceramics, high quality factor, high frequency wireless communication

Procedia PDF Downloads 451

Authors: Ravinder Kataria, Jatinder Kumar, B. S. Pabla

Abstract:

Ultrasonic machining is one of the most widely used non-traditional machining processes for machining of materials that are relatively brittle, hard, and fragile such as advanced ceramics, refractories, crystals, quartz etc. Present article has been targeted at investigating the impact of different experimental conditions (power rating, cobalt content, tool material, thickness of work piece, tool geometry, and abrasive grit size) on over cut in ultrasonic drilling of WC-Co composite material. Taguchi’s L-36 orthogonal array has been employed for conducting the experiments. Significant factors have been identified using analysis of variance (ANOVA) test. The experimental results revealed that abrasive grit size and tool material are most significant factors for over cut.

Keywords: ANOVA, abrasive grit size, Taguchi, WC-Co, ultrasonic machining

Procedia PDF Downloads 367

Authors: Lawal Alkasim, Clement M. Gonah, Zainab S. Aliyu

Abstract:

This work is focus on recovering silicon form photovoltaic cells and repurposing it toward the use in glass, ceramics or glass ceramics as it is made up of silicon material. Silicon is the main back-bone and responsible for the thermodynamic properties of glass, ceramics and glass ceramics materials. Antireflection silicon is soluble in hot alkali. Successfully the recovered material composed of silicon and silicon nitride of the A.R, with a small amount of silver, Aluminuim, lead & copper in the sunshine of crystalline/non-crystalline silicon solar cell. Aquaregia is used to remove the silver, Aluminium, lead & copper. The recovered material treated with hot alkali highly concentrated to produce sodium silicate, which is an alkali silicate glass (water glass). This type of glass is produced through chemical process, unlike other glasses that are produced through physical process of melting and non-crystalline solidification. It has showed a property of being alkali silicate glass from its solubility in water and insoluble in alcohol. The XRF analysis shows the presence of sodium silicate.

Keywords: unrecyclable solar PV, crystalline silicon, hot conc. alkali, sodium silicate

Procedia PDF Downloads 55

Authors: Ravinder Reddy Butreddy, Sadhana Katlakunta

Abstract:

The nanocomposites of CoFe2O4-xZrO2 with different loadings of ZrO2 (x = 0.025, 0.05, 0.075, 0.1 and 1.5) were prepared using ball mill method. All the samples were prepared at 980°C/1h using microwave sintering method. The x-ray diffraction patterns show the existence of tetragonal/monoclinic phase of ZrO2 and cubic phase of CoFe2O4. The effects of ZrO2 on structural and microstructural properties of CoFe2O4 composite ceramics were investigated. It is observed that the density of the composite decreases and porosity increases with x. The magnetic properties such as saturation magnetization (Ms), and Coercive field were calculated at room temperature. The Ms is decreased with x while coercive field is increased with x. The dielectric parameters exhibit the relaxation behavior in high-frequency region and showing increasing trend with ZrO2 concentration, showing suitable

Keywords: dielectric properties, magnetic properties, microwave sintering, nanocomposites

Procedia PDF Downloads 207