High Temperature Ceramics Research Papers (original) (raw)

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- Materials Science, Sensors and Sensing, Sintering, High Temperature Ceramics

Ultra-high temperature ceramics (UHTCs) are interesting materials for a large variety of applications under extreme conditions. This paper reports on the production and extensive characterization of highly dense, pure zirconium and tantalum diborides, with particular interest to their potential utilization in the thermal solar energy field. Monolithic bulk samples are produced by Spark Plasma Sintering starting from elemental reactants or using metal diboride powders previously synthesized by Self-propagating High-temperature Synthesis (SHS). Microstructural and optical properties of products obtained by the two processing methods have been comparatively evaluated. We found that pure diborides show a good spectral selectivity, which is an appealing characteristic for solar absorber applications. No, or very small, differences in the optical properties have been evidenced when the two investigated processes adopted for the fabrication of dense TaB 2 and ZrB 2 , respectively, are compared.

- by Elisa Sani
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- Ceramic Technology, High Temperature Ceramics, Solar Energy Materials, Ceramics

Recently, in situ Raman setups under irradiation become available, and uranium dioxide is one of the most studied compounds. This paper reports the temperature dependence of the only Raman-active mode in fluorine UO2. Besides the interest in terms of phonon anharmonicity knowledge, this can be used to estimate the heating induced by irradiation: The frequency shift and width of the T2g peak can be used as an internal indirect probe of the local temperature in the 20–590 °C range.

ceramics is one of the first raw materials that people use in making their requirements in daily life due to the availability of its materials in the surrounding environment and it has been used in making fashion supplements accurately for easy assortment, and the ceramics industry has progressed greatly to extend and include many things in the artistic, industrial and architectural industries, it is a craft that enjoys originality And contemporary and ease of dealing with it in the formation process as it is one of the crafts that take time to extract a good product with high accuracy through many procedures, processes and tools, and since the advent of the computer, these tools are constantly developing and creating new patterns of new technologies that depend on the capabilities of the computer in Leading these tools, such as numerical control technologies, and in recent times, numerical control technologies have played a major role in various fields.
In this research, an attempt is made to take advantage of numerical control technology to produce ceramic fashion supplements in a way that saves time and effort to obtain a product with high accuracy to revive this kind of art, by using numerical control technology through a small size numerical control machine (mini CNC Router engraver 3Axis). Using the various ceramic bodies and their raw materials available in the surrounding environment, the ceramic production process can be carried out by means of numerical control machines by drilling directly on the clays or by engraving on plaster molds for use in the production process, as well as to benefit from the advantages of the computer in the design and modification processes.

- by Walter Zimbeck
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- High Temperature Ceramics, 3D printing, Additive Manufacturing, Stereolithography
- by DJ Mohanty
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- Photovoltaics, Glass, High Temperature Ceramics, Composite Materials
- by Therese Kearns
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- High Temperature Ceramics, Archaeometallurgy

Author: Ninina Cuomo di Caprio
Publication Date: October 31 2017
Publisher: L'ERMA di BRETSCHNEIDER
Series: Manuali L'ERMA, 2
ISBN: 978-88-913-1012-5 (Print)
ISBN: 978-88-913-1014-9 (E-Book)
Binding: Paperback
Pages: 700, 260 ill. B/N
Size: 21 x 28 cm
From the Foreword by prof. David P. Peacock, University of Southampton, UK
This manual on pottery-making in antiquity is a compendium of almost everything bearing on the interpretation of ancient ceramics in antiquity Because of this, it is likely to remain a standard work for many years to come. Both the student and the more experienced researcher will benefit from this book and will find it easy to follow because of the lively presentation. The whole subject of ceramics is here, from clay acquisition to kilns and firing, backed with an extensive bibliography. It is a work of reference which should have a place on every archaeologist' s bookshelf from their first day at University until retirement
Part Two is titled Modern Laboratory Techniques and provides a summary of the most widely used scientific techniques which can aid the archaeologist in the understanding and interpretation of ancient ceramics.
Cuomo di Caprio, Ninina - Essential Bibliography:
1972 Proposta di classificazione delle fornaci per ceramica e laterizi nell' area italiana, in Sibrium 11, 1971-72, pp. 371-464
1982 Ceramica rustica tradizionale in Puglia, Galatina, Lecce 1982
1985 La ceramica in archeologia. Antiche tecniche di lavorazione e moderne tecniche di analisi, Rome 1985 (reprinted 1988)
1992 Fornaci e officine da vasaio tardo ellenistiche, Morgantina Studies, vol. III, Princeton, New Jersey 1992
1993 La galleria dei falsi. Dal vasaio al mercato di antiquariato, Rome 1993
2007 Ceramica in archeologia 2. Antiche tecniche di lavorazione e moderne tecniche di analisi, (enlarged and revised 1985 edition), Rome 2007.

It has been generally accepted that the beginnings of tin-based opacification of ceramic glazes is associated with the white glazed wares excavated in Iraq and western Iran and dated to the ninth century AD (so-called 'Samarra-type' pottery). This paper focuses on an earlier stage in the technological development of tin-opacified glazes, that is, the yellow and white glazed wares produced from the eighth century AD in Egypt and the Levant. In addition, the compositional data was extended for the subsequent spread of tin-opacified glazes into Mesopotamia in the ninth century and Northern Iran and Central Asia in the tenth century. Using SEM-EDS and SR-Micro-XRD, the chemical composition and microstructure of eighty-five samples of opaque yellow and white glazed wares from Egypt (Fustat), the Levant (Madaba, Aqaba, Al-Mina and Raqqa), Mesopotamia (Samarra, Kish, Basra and Susa), Northern Iran (Takht-i Suleiman), and Central Asia (Nishapur, Merv and Samarqand) were investigated. These data confirmed that the yellow and white glazes were opacified by lead-tin-oxide (PbSnO 3) and tin oxide (SnO 2) particles respectively. Replication experiments were then conducted to imitate typical compositions of the analysed opaque yellow and opaque white glazes. Overall, the results posited the beginning of tin-based opacification of glazes in the eighth century in Egypt and the Levant, and provided explanations as to how the production of opaque yellow and white glazes in the Levant and Mesopotamia might have been technologically linked.

- by Moujan Matin and +1
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- Ceramics (Ceramics), High Temperature Ceramics, Ceramics (Art History), Ceramic Analysis (Archaeology)

Cunha is a small town located in the east part of the state of São Paulo. It was originated in the 18th century, due to the troops that covered the so called “gold path” from Minas Gerais to the port of Paraty-RJ. Since its beginning, Cunha´s history is related to the production of ceramic objects: at first, with utilitarian objects made by women known as Paneleiras, who were influenced by the now extinct ceramics of Indian tribes of the region, and later by the brick factories that enabled the town to re-edify. More recently, in 1975, the arrival of a group of ceramists- most of them foreigners- implanted a different way of thinking this production, that during the past thirty six years propelled the town to become an important Brazilian ceramist center. Our goal is to understand the main characteristics that identify this transformation, in order to answer the question that motivated most of this study: is it
possible to refer to the ceramic production made in Cunha as being, in fact, typically “Cunhan”?
The main part of this text is divided in four chapters; which´s ordering has the goal to compile information in a didactic way that allows the understanding of what we decided to call the Ceramic Path from Cunha. In the first chapter we try to point these paths, revealing some of their historical and aesthetic characteristics. After the understanding of their existence and importance, we can explore the universe of High Temperature, starting with the recognition of the great importance that this study confers to Noborigama kiln. The third chapter is focused on the process of ceramic production and will analyze technical
procedures practiced by nowadays ceramists from Cunha. It shows the preparation of clay, modeling and burning of the pieces. On the end, it analyses the specific dynamic of some
studios, which reveals the visual power of the art pieces made by these ceramists, whose ability grants Cunha national recognition as a reference in the field of ceramic artistic
production in the present days.

- by Kleber Silva
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- High Temperature Ceramics, Ceramics (Art History), Ceramics, Ceramica
- by Dorothy Ko
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- Industrial And Labor Relations, High Temperature Ceramics, Art And Ecology, Trees

Decorative and applied art is born in the interaction of traditions and the constant search for new forms. The enormous potential of the knowledge gained over the past decades in the study of objects from archaeological excavations, ethnographic observations of the results often remain out of sight of contemporary artists. On the other hand, many scientific reconstructions remain speculative, and discoveries are unclaimed. Synthesis of theoretical and practical knowledge will allow to solve this problem. Conference aim is interaction of science and practice, the study of decorative and applied arts in archeology, ethnography, art history and the synthesis of traditions and innovations in contemporary art In the key topic of the theme "From Crafts to Art", it is planned to hold annual conferences within the framework of the cycle: — ceramics and glass; — textiles and other fabrics; — metalwork; — arts and crafts: traditions and innovations 2018 meeting topic is " CERAMICS: TECHNOLOGY, DECOR, STYLE " The following questions will be under discussion: — technology and technique of manufacturing and ornamentation of pottery; — interaction of technology, decor and form in ceramic products; — figurative and abstract shapes in pottery. A common theme for all conferences: — synthesis of technology and forms in various kinds of arts and crafts We invite practitioners, theoreticians, teachers, graduate students and undergraduates to participate in the conference. Proceedings of the conference will be issued in electronic and printed form.

- by Ilia Palaguta
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- Art History, Art Theory, Pottery (Archaeology), Ceramic Technology

Installation of the Old Slaughterhouse Studio in the city of Cunha SP in 1975, is the genesis of a new local potter culture. The pioneer of this group established basis for the creation of one of the most important Brazilian centers of today potters and continues to inspire the creation of new studios that have the burning firewood High Temperature, fundamental part of his poetic creation.
Keywords: High Temperature Ceramics, Cunha, Noborigama Oven, Studio Old Slaughterhouse.

- by Kleber Silva
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- High Temperature Ceramics, Ceramics (Art History), Ceramics, Pottery kilns

TR-2015/09482
Reduction Agents in Reduction Firing with Electical Kiln and Firing Methodology for Reduction Agents

- by Sencer Sari
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- Ceramic Engineering, Ceramic Technology, High Temperature Ceramics, Harm Reduction

Ceramics, has progressed from past to present in a movement in terms of art and technology. In the light of the information have gained, diversity has increased and new attempts have been made to overcome limitations of the ceramics. In this artwork report, sintering studies has carried out with the use of rice husk as quartz in ceramic structures. Raw material is the material used for producing products or goods. Quartz is a self-contained ceramic raw material. Rice husk ash has shown as an alternative raw material to quartz, and it has tried to contribute to the diversity of ceramic raw materials.
Quartz, one of the raw materials used in ceramic structure and glaze prescriptions, is a crystal form of silica. Quartz is a mineral and its chemical structure consists of silicon and oxygen. Quartz can be found in nature in crystal and amorphous form. Quartz in ceramic prescriptions; It facilitates the drying of the buildings, controls the downsizing, provides whiteness and increases the resistance to heat. It prevents the formation of glaze cracks by ensuring good adhesion of ceramics and glaze. Rice husk can be converted into amorphous, fine-grained silica after calcination. Silica in the rice husk ash has the same essence as the crystalline state of the quartz silica, which is a ceramic raw material.
Because of the high amount of silica in the content of the rice husk ash, it is thought that instead of the quartz which is obtained from the rocks, rice husk ash can be use in sinter structure prescriptions.
In this study, the rice husks cause stacks in the nature has transformed into quartz. Rice husk ash transformed into quartz has been added to the prescriptions at various ratios. The possibilities of obtaining and using the rice husk have been investigated.

- by Kedar shukla
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- Engineering Physics, High Temperature Ceramics, Finite element method, Silica

This paper presents new data from the Husi kiln site, Hubei Province, China, where the unusual size calls into question the primacy of Jingdezhen in porcelain production in medieval China. With its over 180 kilns, the site rivals Jingdezhen in size, yet it has found no mention in textual accounts. The wares produced at Husi include Qingbai and grey-greenish ware of the Tang and the Song periods (seventh to thirteenth century AD). This paper presents compositional data obtained using LA-ICP-MS on samples from five kilns at Husi, comparing them with published data from other kilns. The data set Husi apart, thus allowing for fingerprinting its wares. Based on bulk chemical analysis, the paper furthermore explores the idea that Husi combined elements of southern and northern technologies, thus connecting these two ceramic traditions that previously had been seen as being entirely separate. Some key elements of the early Qingbai ware glaze from Husi resemble wares from Jingdezhen, sugges...

- by Anke Hein
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- Archaeology, Geology, High Temperature Ceramics, Chinese Porcelain

RATIONALE: Materials based on the Yb 2 O 3-ZrO 2 system have many industrial applications such as high-temperature solid electrolytes, ceramics with special properties and most importantly for thermal barrier coatings. As their synthesis and use take place at high temperatures, information on the vaporization processes, thermodynamic properties and phase equilibria of this system at high temperatures is of great importance. METHODS: Measurements were performed by high-temperature Knudsen effusion mass spectrometry with a MS-1301 mass spectrometer. Vaporization was carried out using two tungsten effusion cells containing the sample under study and pure Yb 2 O 3. The values of component activities in the Yb 2 O 3-ZrO 2 system were also calculated using the CALPHAD approach. RESULTS: The Yb and O vapor species were identified over the samples studied at 2400 K. Using these data the ZrO 2 activities, chemical potentials of components and the Gibbs energies of the solid solution formation were calculated in this system. The thermodynamic values were also obtained as the result of modeling of the Yb 2 O 3-ZrO 2 system based on the CALPHAD approach using the data available on the phase diagram of this system and calorimetric measurements only. CONCLUSIONS: The thermodynamic functions found in the Yb 2 O 3-ZrO 2 system at 2400 K, such as the activities of components and the Gibbs energy of formation, displayed negative deviation from ideality. Mutual agreement was observed between the experimental thermodynamic values and the results of calculations based on the CALPHAD approach.

- by Sergey M Shugurov
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- High Temperature Ceramics, Zirconia Ceramics, Solid Solution

Calcium-stabilized alpha-sialon ceramics reinforced with cubic boron nitride (cBN) particles were synthesized using spark plasma sintering. The effects of the size of alpha-sialon precursor particle and the influence of the amount of cBN reinforcement on the physical, structural and mechanical characteristics of the composites were studied. Synthesis of the composites at 1500 C with a holding time of 30 min resulted in densified composites. CBN-reinforced alpha-sialon composites synthesized via probe soni-cation showed particle sizes between 200 nm and 450 nm and showed significantly better mechanical properties than did the unreinforced sialon. A Vickers hardness (H V10) value of as high as 24.0 GPa was measured for this reinforced sialon, as compared to a value of 21.6 GPa for the pure alpha sialon. However, a phase transformation from alpha to beta sialon was observed when using high energy ball milling process condition, where the size of the alpha-forming precursors was decreased to about 100 nm. This phase transformation was accompanied by a simultaneous cubic-to-hexagonal boron nitride phase transformation.

- by Anwar Ul-Hamid
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- Materials Science, High Temperature Ceramics, Sialon

RATIONALE: Zirconia doped with a lanthanum oxide system is of high interest due to its exceptional thermal stability for the development of high performance ceramics. It possesses the beneficial properties of pure zirconia, such as heat resistance, mechanical strength and inertness, but also eliminates its main disadvantage, i.e. brittleness. At high temperatures, components of such systems may vaporize selectively, leading to significant change in composition, and hence, the thermal resistance, phase stability and performance of the ceramic materials. Therefore, information on the vaporization processes and thermodynamic properties of the La 2 O 3-ZrO 2 system is of great importance.

- by Sergey M Shugurov and +1
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- High Temperature Ceramics, Zirconia, Solid Solution

High-temperature properties of boron nitride platelets (200-800 nm in width and 30-50 nm in thickness) were systematically evaluated through thermogravimetric analysis (TGA) in combination with differential scanning calorimetry (DSC). X-Ray Diffraction (XRD) studies conﬁrmed the hexagonal graphitic-like structure of the material, while Fourier-Transform Infrared Spectroscopy (FT-IR) indicated the active vibration modes related to the BeN bond. The speciﬁc surface area (SSA), calculated by the multi-point Brunauer-Emmet-Teller (BET) method, was determined at ~23 m2/g through N2 adsorption/desorption measurements at 77 K. Both high-temperature resistance and oxidation behavior were examined from room temperature (25 􀀀oC) up to ~1300 o􀀀C under air-ﬂow conditions. The h-BN platelets demonstrated a high thermal stability of up to ~1000 o􀀀C, while their oxidation occurred in the tem-perature range between 1000 and 1200 o􀀀C, followed by the formation of boron oxide (B2O3).

- by Nikolaos Kostoglou
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- High Temperature Ceramics, Nanomaterials, Nanoparticles, Boron Nitride

Sulfuric acid is one of the largest produced chemicals in the world and a large percentage is recycled through thermal decomposition. The nozzles that inject spent sulfuric acid into a thermal decomposition furnace plague the process with high levels of corrosion. The interface of high temperature gas and aqueous sulfuric acid creates a unique mode of corrosion. A search for a nozzle material that is resistant to such rapid
deterioration and expensive replacement is therefore warranted. Ceramics being somewhat superior to metals and alloys in terms of their corrosion resistance in an acidic medium, lanthanum phosphate monazite was considered as a new alternative material to compose the nozzles and thus increase the resistance to corrosive failure.
Lanthanum phosphate monazite was selected for this purpose because of its wide range of applications in extreme and corrosive atmospheres. The material has been reported to perform well as a ceramic for radioactive waste storage, ceramic matrix composites in turbine applications, a machinable ceramic, and a good proton conductor
for sensors and fuel cells. Lanthanum phosphate monazite was thought to be a good candidate to compose the nozzles because of the similarities with its other applications under conditions that a nozzle in spent acid treatment typically experiences. Testing was done to determine if the material could function as a structural ceramic substitute to the
currently used alloys, at the operating temperatures and, if it would withstand the aqueous mode of corrosion and the high temperature gaseous corrosion. During the material corrosion analysis details of the corrosion process within the furnace were further defined. The results were compared to other materials for analysis and recommendation. The findings establish a clear set of directives for future research considering nozzle corrosion, including the promising potential of using Al2O3-LaPO4 composite as the new material.

Sodium cobalt oxide (NaCo2O4) nanocrystalline thermoelectric ceramic powders were synthesized using conventional polymerized complex sol–gel and electrospinning techniques and then consolidated into bulk ceramics. We have investigated the differences in the microstructure and thermoelectric properties of the samples prepared using electrospinning and sol–gel methods. The crystal structures of the powders and nanofibers were characterized using X-ray diffraction and scanning electron microscopy before and after calcination at different temperatures. Nanofibers prepared by electrospinning have a diameter of approximately 300 nm, while the diameter of the grains of sol–gel powders ranges from 1 to 5 µm. Thermoelectric properties of the bulk ceramics were measured by physical properties measurement system in the temperature range of 15–300 K. The calculated values of dimensionless figure of merit at 300 K are 6 × 10−7 and 4 × 10−5 for sintered powders from sol–gel and nanofibers, respectively. While electrospinning production technique increase thermoelectric power approximately 15 % and it fold electrical conductivity average 20 times, it decreased thermal conductivity by 90 %.

- by Prof.Dr. İbrahim USLU and +1
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- Polymer Chemistry, Ceramic Technology, Nanomaterials Characterization, High Temperature Ceramics

Samples were collected from the argillic alteration zones in Sappes area, Thrace, Northern Greece and were examined for their mineralogical composition. Results showed that the sericite zone is the most widespread type of alteration in the studied area, followed by the transitional sericite–kaolinite zone and finally the pyrophyllite-rich zone. After determination of the spatial distribution of the different argillic alteration zones, selected samples were examined for their technological ceramic properties in order to evaluate their use in ceramic production. Preliminary results showed that after beneficiation processes, the clayey raw material from the alteration zones could be used in the ceramic industry.

RESUMEN La empresa peruana Cerartec S.A ha elaborado aisladores eléctricos cerámicos para usos en líneas de tensión media. Estos productos, tipo carrete ANSI 53-2 (" Spool and Guy Strain Insulators "), llevan mayormente materias primas de origen nacional. El protocolo de elaboración y la formulación afectan la porosidad residual. Los factores relevantes, tanto de formulación como de proceso, han sido determinados. En el rango estudiado, existe una relación lineal entre el módulo de rotura en flexión y la porosidad. Se comprobó también la resistencia dieléctrica de los aisladores en seco y húmedo. ABSTRACT The Peruvian company Cerartec S.A has developed ceramic-based electrical insulators for medium voltage lines. These products, ANSI 53-2 type (Spool and Guy Strain Insulators), are composed mainly of peruvian raw materials. Both formulation and process have an influence on residual porosities. Relevant parameters of formulation and process have been identified. In the investigated range, a linear relationship was drawn between porosities and flexural modulus of rupture. The new ceramic electrical insulators have been tested in terms of dielectric resistance, in dry and wet conditions.

- by DOMINIQUE GEORGES JEAN PLEE MOREAU and +1
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- High Temperature Ceramics

ZnO based varistors are widely used for overvoltage protection in many electrical and electronic circuits, at
voltages ranging from a few to over a million volts. By careful control of the microstructure, through nanostructuring
by chemical routes, it should be possible to produce varistors with high breakdown voltage (Vc),
as this is proportional to the number of active grain boundaries in the sintered body. This property is
particularly important for the production of the small-sized varistors needed for modern electronic
instruments such as tablet computers and mobile phones. The current review will outline the recent
advances in the chemical processing (e.g. sol–gel, combustion synthesis plasma pyrolysis, micro-emulsion
synthesis and precipitation routes) of varistors from ZnO nanomaterials and the properties of these
materials. Uncontrolled grain growth at higher temperature is highlighted as a major challenge for
obtaining desirable electrical properties for nano-varistors. Various novel sintering techniques such as
step-sintering, spark plasma and microwave sintering methods are expected to deliver a varistor with
controlled grain growth and optimum electrical characteristics.

- by J. Kelly and +2
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- Materials Engineering, Materials Science, Synthesis of nanoparticles, Composite Materials and Structures

The order‐disorder phase transition in Ba2In2O5 high‐temperature ionic conductor was systematically studied by in situ high‐temperature X‐ray diffraction using synchrotron radiation and electrical conductivity. Pure barium indate was prepared by solid state reactions at 1300 °C. The room‐temperature structural characterization showed a high degree of phase homogeneity in the prepared material. The reduction of the order‐disorder phase transition temperature was verified by electrical conductivity and high‐temperature X‐ray diffraction. The observed features were explained based on Fourier‐transform infrared spectroscopy results that revealed the presence of hydroxyl species in the crystal lattice. The increase of the intensity of few diffraction peaks near the phase transition temperature suggests the formation of a superstructure before the orthorhombic‐to‐tetragonal phase transition.

- by José Rey and +1
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- High Temperature Ceramics, Phase Transitions
- by Sergey M Shugurov
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- High Temperature Ceramics
- by Eleni Koutsopoulou
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- High Temperature Ceramics, Ceramics, Hydrothermal Alteration, Kaolinite Clay

- by Oliver Watson
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- Archaeology, Geochemistry, Archaeological Science, High Temperature Ceramics

Available information concerning the elastic moduli of refractory carbides at temperatures (T) of relevance for practical applications is sparse and/or inconsistent. Ab initio molecular dynamics (AIMD) simulations at T = 300, 600, 900, and 1200 K are carried out to determine the temperature-dependences of the elastic constants of rocksalt-structure (B1) TiC, ZrC, HfC, VC, TaC compounds, as well as high-entropy (Ti,Zr,Hf,Ta,W)C and (V,Nb,Ta,Mo,W)C. The second-order elastic constants are calculated by least-square fitting of the analytical expressions of stress/strain relationships to simulation results obtained from three tensile and three shear deformation modes. Sound-velocity measurements are employed to validate AIMD values of bulk, shear, and elastic moduli of single-phase B1 (Ti,Zr,Hf,Ta,W)C and (V,Nb,Ta,Mo,W)C at ambient conditions. In comparison with the predictions of previous ab initio calculations – where the extrapolation of finite-temperature elastic properties accounted for thermal expansion while neglecting intrinsic vibrational effects – AIMD simulations produce a softening of shear elastic moduli with T in closer agreement with experiments. The results show that TaC is the system which exhibits the highest elastic resistances to tensile and shear deformation up to 1200 K, and indicate the (V,Nb,Ta,Mo,W)C system as candidate for applications that require superior toughness at room as well as elevated temperatures.

- by davide giuseppe sangiovanni and +1
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- High Temperature Ceramics, Ceramics, Temperature Dependence, Elastic Constants

The evaporation of perovskite CaTiO3 at 1700-2200 K was studied by the high-temperature mass-spectrometric Knudsen effusion method. The molecular components typical of simple oxides and a small amount of complex gaseous oxide CaTiO3 were identified in the gas phase over perovskite. The partial vapor pressures of the molecular components of the gas phase over perovskite were compared with those corresponding to simple oxides; it was found that the character of evaporation of perovskite is mainly affected by the calcium component.

- by Sergey Shornikov
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- High Temperature Ceramics

High-purity, fine-grained alumina showed a strong R-curve behavior for long cracks propagated at 1200°C. R-curve behavior was not observed at room temperature. A combined investigation using high-frequency scanning acoustic microscopy and scanning electron microscopy of crack profiles demonstrated asperity contact in the crack wake at 1200°C. A microcrack zone was not observed. Crack bridging, resulting from intergranular subcritical crack propagation was considered to be responsible for the toughness increase with increased crack length.

Abstract The Era of Matrix Ceramics is the outcome of Engineering Science, when the Science (Physics & Chemistry) of Ceramic’s materials and the Engineering of the fabrications of Ceramic Products and of the Fast Firing kilns were... more

- by Anil K Gupta
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- High Temperature Ceramics

Great advances have been made in various 3-D printing methods for ceramics. [1,2] Fabrication of Si-based ceramics using polymer derived ceramics (PDC) is gaining popularity. [3,4] Using this route, preceramic polymers can be shaped in the polymer state and then pyrolyzed to produce different type of ceramics. [5,6] Cellular ceramics can be manufactured using this technique. [7] This study reports on the novel fabrication of cellular ceramics with a two-step process using PDCs. First cellular structures are 3-D printed with fused filament fabrication (FFF) using thermoplastic polyurethane and impregnated with preceramic polymer polysilazane. Second, pyrolysis of the impregnated structure produces a self-similar ceramic cellular structure. This study systemically evaluates the impact of i) catalysts, ii) curing environment and iii) pyrolysis sequence optimization to form cellular ceramics with fully-dense SiOC(N) struts. The resultant custom ceramic components can tolerate operating temperatures of 1500 o C and can be manufactured for less than 5% of the cost of competing methods. The ceramic material is shown to be biocompatible and promotes fast cell adhesion. Finally, early-stage cell activation on the SiOC(N) structure is shown to be tunable by adjusting the porosity with this 3-D printing to mimic the bone tissue geometry for bone regeneration.

- by Joshua Pearce
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- Materials Engineering, Ceramic Engineering, Materials Science, Biomaterials

Sr1-2xNaxNdxBi4Ti4O15 (x = 0.1, 0.2 and 0.4) system is prepared by sol gel method involving Pechini process of modified polymeric precursor method. Phase identification is done using X-ray diffraction. Conduction in prepared materials involves different mechanisms and is explained through detailed AC and DC conductivity studies. AC conductivity studies carried out on the samples at different frequencies and different temperatures gives more information about electrical transport. Exponents used in two term power relation helps us to understand the different hopping mechanism involved at low as well as high frequencies. Activation energies calculated from the Arrhenius plots are used to calculate activation energies at different temperatures and frequencies. Hopping frequency calculated from the measured data explains hopping of charge carriers at different temperatures. DC conductivity studies help us to know the role of oxygen vacancies in conduction.

Activated Alumina ball having a lot of white pellets capillary channel , there are many pores channel , these channels have a higher activity on the surface , to the gas , vapor, liquid water has a selective adsorption ability . Under certain conditions, drying depth of up to -70 ℃ below the dew point, saturation at 175 ℃ -400 ℃ heating in addition to water and resurrection , can many times, also from the contaminated oxygen, hydrogen, sulfur dioxide adsorption lubricants and other oil steam , may make the catalyst or carrier. Widely used in petrochemical , oil refining , electronics, ethylene, propylene, air drying device , the country has a lot of hydrogen peroxide plant , fertilizer plant, oxygen plant and petrochemical refining units , and achieved good results.
Activated alumina ball of the adsorbed substances to determine the strength of the polarity of water , oxide, acetic acid, alkali and other strong affinity is a micro water depth of desiccant is adsorbed polar molecules adsorbed agent.

Natural fibers nowadays have become attractive to researchers as an alternative to synthetic fiber to be used as reinforcing element in terms of strength, modulus and hardness. These include low cost, high specific strength, good mechanical property, non-abrasive, corrosion resistance, biodegradability in comparison to conventional glass, aramid and carbon fibers. Flexural properties are mainly influenced by the interfacial bonding between fiber and matrix. Conventional Hand-lay-up technique was adopted for preparing composites, Firstly, Hardness of each specimen had been taken. Then, composites were made by aligning untreated fiber, 2%NaOH and 4%NaOH treated palm leaf fiber into the matrix (polyester resin). There is a gradual increase in the value of the yield strength and modulus ranging from pure composite to untreated fiber, then to 2%treated fiber and then to 4% NaOH treated fiber reinforced composites. These experiments were repeated using 10 multiplication load condition to further investigate the enhancement of flexural strength, modulus and hardness comparing to unloaded condition observed.

LaZrTa3O11 ceramic with α-U3O8-type structure has been prepared by using the conventional solid state-route and studied by using powder X-ray diffraction for phase analysis and impedance spectroscopy for electrical measurements. It has hexagonal unit cell with space group P6322 at room temperature. LaZrTa3O11 is reported to be isostructural with CaTa4O11 and Ag2Nb4O11; the structure is related to U3O8-structure, where it consists of single layers of edge-sharing pentagonal Ta-O bipyramids alternating with layers of edge-sharing octahedra. The impedance spectroscopy response showed that LaZrTa3O11 exhibited a typical insulating behaviour at room temperature, with permittivity, ε ~ 19. It was a highly resistive material with R >> 109 Ω at temperature below 500o C and as the temperature increased, frequency-dependence of alternating current conductivities at high frequency was clearly visible. The electrical properties of LaZrTa3O11 is best modelled by using non-Debye response circuit that consists of a parallel combination of a resistor, capacitor, and a constant phase element.

- by Fadhlina Ros
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- High Temperature Ceramics, Dielectrics, Ceramics and electroceramics