scholarly journals Physical-chemical processes of obtaining ceramic materials based on nanopowders of oxides of zirconium, yttrium, cerium and aluminum

2019 ◽  
pp. 61-71
Author(s):  
E. N. Makarova ◽  
I. V. Antsiferova
Keyword(s):  
Fracture Toughness ◽  
Sol Gel ◽  
Experimental Studies ◽  
Chemical Deposition ◽  
Functional Materials ◽  
Ceramic Materials ◽  
Production Method ◽  
Scientific Data ◽  
Oxide Content ◽  
Negative Effect

In the study of nanoceramics, it is necessary to constantly keep in mind the closest interrelation of the production method with its structure and properties. Nanoceramic materials are used in various technical fields as structural and functional materials. It is also widely used in medicine. Nanoceramics is harmless, stable and has a great affinity with living organisms. ZrO2-based nanoceramics have a lower elastic modulus than other oxide materials. The specificity of its application lies in high resistance to rupture and thermal shock, in chemical stability at high temperatures. However, it is necessary to solve the problem of increasing the fracture toughness of ZrO2-based ceramic materials. The complex doping of ZrO2 with yttrium and cerium oxides and the use of an Al2O3 additive increase the fracture toughness and decrease the negative effect of materials in a biological environment. In this paper, the main physicochemical properties of ceramic powders and materials of the ZrO2–2Y2O3–4CeO2 – Al2O3 system, synthesized by chemical deposition of inorganic precursors using the sol-gel technology, are considered on the basis of scientific data and experimental studies. The doping of pure zirconium oxide with stabilizing oxides Y2O3, CeO2, and thermal hardening of Al2O3 ensures that the tetragonal structure is maintained at room temperature, which makes it possible to slow down and control the crack resistance of the material under load. The effects of sintering temperature and aluminum oxide content on the microstructure and grain size, as well as the physicomechanical properties of the resulting ceramic material of ZrO2–2Y2O3–4CeO2+1 wt.% Al2O3 and ZrO2–2Y2O3–4CeO2+3 wt.% Al2O3 were studied.

In situ Synthesis of High Refractive Index PDMS/Metal Oxide Nanocomposites

2012 ◽  
Vol 1400 ◽  
Author(s):  
Qiaoyu Lu ◽  
Michael E. Mullins
Keyword(s):  
Refractive Index ◽  
Metal Oxide ◽  
Hybrid Materials ◽  
Sol Gel ◽  
Heat Stability ◽  
Ceramic Materials ◽  
High Refractive Index ◽  
Oxide Content ◽  
Metal Alkoxides ◽  
Silicone Polymers

ABSTRACTOrganic-inorganic hybrids have been prepared with tailorable and enhanced properties which are unachievable using polymers or ceramics alone. By combining the flexibility of polymers with the electronic and optical properties of ceramic materials, these hybrids offer great potential for many optical, electrical and mechanical applications. Silicone polymers because of their desirable surface properties, excellent physical properties, heat stability, and high resistance to chemical and UV attack, have been widely used. Hybrid siloxane-metal oxide gels have been prepared via sol-gel techniques, by using hydroxyl-terminated polydimethylsiloxanes (PDMS) crosslinked by metallic alkoxides, M(OR)n. In this technique, the use of organic solvents permits organic and inorganic components to be combined at a molecular level with the desired composition. By varying the type and percentage of metal alkoxides during synthesis, transparent and homogeneous organic-inorganic hybrid materials with unique properties were obtained. Also a secondary metal oxide species was introduced to synthesize binary metal oxide-PDMS hybrids. Systematic experiments were carried out to study the effect of the reaction conditions and metal alkoxides-PDMS ratios on the properties of the final hybrids. These hybrids were spin coating on silicon wafers or molded into bulk films to be tested. The composition and the properties of the transparent inorganic-organic hybrids were investigated and characterized by ellipsometer and Fourier Transform Infrared (FTIR) spectroscopy. Experimental results showed that the refractive index of the hybrid materials exhibits a proportional relationship with the metal oxide content, the higher the metal oxide content the higher the refractive index. The refractive index was increased from 1.4 of PDMS to 1.7 of metal oxide-PDMS hybrid with highest prepared metal oxide loading. From the FTIR spectra, the structures of the hybrids for various metal oxide-PDMS compositions were examined.

Phase separation in sol gel-derived ceramic films of silica-zirconia, alumina-zirconia, and titania-zirconia system

1994 ◽  
Vol 52 ◽  
pp. 646-647
Author(s):  
J. Tong ◽  
L. Eyring
Keyword(s):  
Fracture Toughness ◽  
Phase Separation ◽  
Sol Gel ◽  
Great Influence ◽  
High Strength ◽  
Chemical Durability ◽  
Separation Method ◽  
Toughening Mechanism ◽  
Ceramic Films ◽  
Zirconia Toughened Alumina

There is increasing interest in composites containing zirconia because of their high strength, fracture toughness, and its great influence on the chemical durability in glass. For the zirconia-silica system, monolithic glasses, fibers and coatings have been obtained. There is currently a great interest in designing zirconia-toughened alumina including exploration of the processing methods and the toughening mechanism.The possibility of forming nanocrystal composites by a phase separation method has been investigated in three systems: zirconia-alumina, zirconia-silica and zirconia-titania using HREM. The morphological observations initially suggest that the formation of nanocrystal composites by a phase separation method is possible in the zirconia-alumina and zirconia-silica systems, but impossible in the zirconia-titania system. The separation-produced grain size in silica-zirconia system is around 5 nm and is more uniform than that in the alumina-zirconia system in which the sizes of the small polyhedron grains are around 10 nm. In the titania-zirconia system, there is no obvious separation as was observed in die alumina-zirconia and silica-zirconia system.

Perspective Biomass Carrier for Anaerobic Processing Systems of Organic Waste AIC

2020 ◽  
Vol 67 (1) ◽  
pp. 148-155
Author(s):  
Anatoliy V. Fedotov ◽  
Viktor S. Grigoriev ◽  
Dmitriy A. Kovalev ◽  
Andrey A. Kovalev
Keyword(s):  
Wastewater Treatment ◽  
Anaerobic Digestion ◽  
Specific Surface ◽  
Organic Waste ◽  
Porous Ceramic ◽  
Experimental Studies ◽  
Ceramic Materials ◽  
Porous Ceramics ◽  
Developed Surface ◽  
Highly Porous

To speed up the wastewater treatment under aerobic conditions and to optimize the processes of anaerobic wastewater treatment in digesters, immobilization technologies of microorganisms and enzymes on solid carriers are used. Ceramic carriers based on aluminosilicates and alumina are one of the promising inorganic biomass carriers. (Research purpose) To study the structure of porous ceramic biomass carriers for anaerobic processing of organic waste and evaluate the prospects for their use. (Materials and methods) The substrate for anaerobic digestion was a mixture of sediments of the primary and secondary sewage sumps of the Lyubertsy treatment facilities. K-65 cattle feed was used to ensure the constancy of the composition of organic substances in substrates as a cosubstrate. The authors used the method of low-temperature nitrogen adsorption of Bruner-Emmett-Teller to study the pore structure and specific surface of solid carriers on a specific surface analyzer Quntachrome Autosorb-1. (Results and discussion) The main characteristics (specific surface, volume of micro- and mesopores, predominant pore radius, water absorption and others) of chamotte foam lightweight and highly porous corundum ceramics were determined. It was revealed that ceramic materials with a developed surface and electrically conductive material provided an increase in biogas yield by 3.8-3.9 percent with an increase in methane content by an average of 5 percent. (Conclusions) The results of anaerobic digestion showed a positive effect of both a conductive carrier and highly porous ceramic materials on the process of anaerobic bioconversion of organic waste into biogas. It is advisable to expand experimental studies on the use of a conductive carrier with a developed surface based on highly porous ceramics.

Sol-gel and SPS combined synthesis of highly porous wollastonite ceramic materials with immobilized Au-NPs

2017 ◽  
Vol 43 (11) ◽  
pp. 8509-8516 ◽  
Author(s):  
E.K. Papynov ◽  
O.O. Shichalin ◽  
V.Yu. Mayorov ◽  
E.B. Modin ◽  
A.S. Portnyagin ◽  
...  
Keyword(s):  
Sol Gel ◽  
Ceramic Materials ◽  
Au Nps ◽  
Highly Porous

scholarly journals Elucidation of the Crystal Growth Characteristics of SnO2 Nanoaggregates Formed by Sequential Low-Temperature Sol-Gel Reaction and Freeze Drying

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1738
Author(s):  
Saeid Vafaei ◽  
Alexander Wolosz ◽  
Catlin Ethridge ◽  
Udo Schnupf ◽  
Nagisa Hattori ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Freeze Drying ◽  
Sno2 Nanoparticles ◽  
Sol Gel ◽  
Functional Materials ◽  
Cost Effective ◽  
High Concentration

SnO2 nanoparticles are regarded as attractive, functional materials because of their versatile applications. SnO2 nanoaggregates with single-nanometer-scale lumpy surfaces provide opportunities to enhance hetero-material interfacial areas, leading to the performance improvement of materials and devices. For the first time, we demonstrate that SnO2 nanoaggregates with oxygen vacancies can be produced by a simple, low-temperature sol-gel approach combined with freeze-drying. We characterize the initiation of the low-temperature crystal growth of the obtained SnO2 nanoaggregates using high-resolution transmission electron microscopy (HRTEM). The results indicate that Sn (II) hydroxide precursors are converted into submicrometer-scale nanoaggregates consisting of uniform SnO2 spherical nanocrystals (2~5 nm in size). As the sol-gel reaction time increases, further crystallization is observed through the neighboring particles in a confined part of the aggregates, while the specific surface areas of the SnO2 samples increase concomitantly. In addition, X-ray photoelectron spectroscopy (XPS) measurements suggest that Sn (II) ions exist in the SnO2 samples when the reactions are stopped after a short time or when a relatively high concentration of Sn (II) is involved in the corresponding sol-gel reactions. Understanding this low-temperature growth of 3D SnO2 will provide new avenues for developing and producing high-performance, photofunctional nanomaterials via a cost-effective and scalable method.

scholarly journals Tough metal-ceramic composites with multifunctional nacre-like architecture

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Erik Poloni ◽  
Florian Bouville ◽  
Christopher H. Dreimol ◽  
Tobias P. Niebel ◽  
Thomas Weber ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Sol Gel ◽  
Ceramic Composites ◽  
High Fracture Toughness ◽  
Processing Route ◽  
High Fracture ◽  
Metal Ceramic ◽  
Attractive Option ◽  
Brick And Mortar ◽  
Robotic Applications

AbstractThe brick-and-mortar architecture of biological nacre has inspired the development of synthetic composites with enhanced fracture toughness and multiple functionalities. While the use of metals as the “mortar” phase is an attractive option to maximize fracture toughness of bulk composites, non-mechanical functionalities potentially enabled by the presence of a metal in the structure remain relatively limited and unexplored. Using iron as the mortar phase, we develop and investigate nacre-like composites with high fracture toughness and stiffness combined with unique magnetic, electrical and thermal functionalities. Such metal-ceramic composites are prepared through the sol–gel deposition of iron-based coatings on alumina platelets and the magnetically-driven assembly of the pre-coated platelets into nacre-like architectures, followed by pressure-assisted densification at 1450 °C. With the help of state-of-the-art characterization techniques, we show that this processing route leads to lightweight inorganic structures that display outstanding fracture resistance, show noticeable magnetization and are amenable to fast induction heating. Materials with this set of properties might find use in transport, aerospace and robotic applications that require weight minimization combined with magnetic, electrical or thermal functionalities.

Impact of the Limestone Powder on the Properties of Cement Paste and Mortar

2012 ◽  
Vol 174-177 ◽  
pp. 236-240
Author(s):  
Jing Zhang ◽  
Zhu Li
Keyword(s):  
Mechanical Properties ◽  
Cement Paste ◽  
Experimental Studies ◽  
Water Requirement ◽  
Limestone Powder ◽  
Inert Material ◽  
Normal Concrete ◽  
Significant Negative Effect ◽  
Negative Effect

Experimental studies on the properties of cement paste and mortar with the use of limestone powder were carried out. The results show that the replacement with 10% to 30% limestone powder in cement paste can reduce the water requirement for certain flowability. As an inert material, the use of the limestone powder has significant negative effect on the mechanical properties of mortar. However, strength requirement of normal concrete (mortar) can be reached by reducing the water to cementious material ratio, which makes the use of limestone powder as a replacement of cement possible.

Control of Hierarchically Ordered Positive and Negative Replicas of Wood Cellular Structures by Surfactant-Directed Sol-Gel Mineralization

2002 ◽  
Vol 726 ◽  
Author(s):  
Yongsoon Shin ◽  
Jun Liu ◽  
Li-Qiong Wang ◽  
Jeong Ho Chang ◽  
William D. Samuels ◽  
...  
Keyword(s):  
Silicic Acid ◽  
Cell Walls ◽  
Cellular Structure ◽  
Sol Gel ◽  
Ceramic Materials ◽  
Silica Particles ◽  
Low Ph ◽  
Cellular Structures ◽  
Inner Surface

AbstractWe here report the synthesis of ordered ceramic materials with hierarchy produced by an in-situ mineralization of ordered wood cellular structures with surfactant-templated sol-gel at different pH. At low pH, a silicic acid is coated onto inner surface of wood cellular structure and it penetrates into pores left, where degraded lignin and hemicellulose are leached out, to form a positive replica, while at high pH the precipitating silica particles due to fast condensation clog the cells and pit structures to form a negative replica of wood. The calcined monoliths produced in different pHs contain ordered wood cellular structures, multi-layered cell walls, pits, vessels well-preserved with positive or negative contrasts, respectively. The surfactant-templated mineralization produces ordered hexagonal nanopores with 20Å in the cell walls after calcination.

Effects of TiN Content on Mechanical Properties and Microstructure of ATN Materials

2013 ◽  
Vol 589-590 ◽  
pp. 590-593 ◽  
Author(s):  
Min Wang ◽  
Jun Zhao
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Fracture Toughness ◽  
Vickers Hardness ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Ceramic Materials ◽  
Hot Press ◽  
Hot Press Sintering ◽  
Tin Content

In order to investigate the effects of TiN content on Al2O3/TiN ceramic material (ATN), the ATN ceramic materials were prepared of TiN content in 30%, 40%, 50%, 60% in the condition of hot press sintering. The sintering temperature is 1700°C, the sintering press is 32MPa, and the holding time are 5min, 10min, 15min. The effects of TiN content on mechanical properties and microstructure of ATN ceramic materials were investigated by analyzing the bending strength, hardness, fracture toughness. The results show that ATN50 has the best mechanical property, its bending strength is 659.41MPa, vickers hardness is 13.79GPa, fracture toughness is 7.06MPa·m1/2. It is indicated that the TiN content has important effect on microstructure and mechanical properties of ATN ceramic materials.

Cholesterol decorated pyridinium urea and carbamate as π-gelators for selective recognition of F- ions

2021 ◽  
Vol 05 ◽  
Author(s):  
Santanu Panja ◽  
Kumaresh Ghosh
Keyword(s):  
Sol Gel ◽  
Functional Materials ◽  
Materials Chemistry ◽  
Eye Detection ◽  
Fluoride Ions ◽  
Biologically Relevant ◽  
Design And Synthesis ◽  
Naked Eye ◽  
Visual Sensing ◽  
Naked Eye Detection

Aim: Design and synthesis of new molecules capable of forming self-assembled gels are indispensable to harvest new functional materials. Supramolecular gels have potential in many areas particularly in biology and materials chemistry. Of the different types of applications, visual sensing of biologically relevant ionic analytes is a fairly recent trend. Here we describe naked eye detection of fluoride ions involving sol-gel methodology. Methods: To execute this, cholesterol substituted pyridinium salts 1-4 have been designed and synthesized of which compounds 3 and 4 served as potential gelators for the naked eye detection of F- ions in DMSO and DMSO-H2O (1:1, v/v) respectively. Results: Gelation study reveals that not only the aromatic surface is crucial for the self-aggregation of molecules via π-π stacking interactions, but also polarity, rigidity and conformational flexibility of the molecules that govern the intermolecular association of gelators are important. Conclusion: Moreover, incorporation of fluorophores (naphthalene) as aromatic surface in the molecular designs, promotes the gelator molecules to execute sensing behavior for F- with high degree of sensitivity in solution phase also.

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