Powder synthesis of barium titanate and barium orthotitanate via an ethylene glycol complex polymerization route

1999 ◽  
Vol 14 (7) ◽  
pp. 3001-3006 ◽  
Author(s):  
S. J. Lee ◽  
M. D. Biegalski ◽  
W. M. Kriven
Keyword(s):  
High Temperature ◽  
Barium Titanate ◽  
Ethylene Glycol ◽  
Orthorhombic Phase ◽  
Orthorhombic Symmetry ◽  
Powder Synthesis ◽  
Scanning Calorimetry ◽  
Powder Morphology ◽  
Synthesis Of Barium Titanate ◽  
Volume Decrease

Pure and reactive barium titanate (BaTiO3) and barium orthotitanate (Ba2TiO4) powders have been synthesized by an ethylene glycol (EG), polymerizationcomplexation route. The EG content affected the crystallization behavior and powder morphology. The BaTiO3powder, which had a particle size of approximately 100 nm, crystallized from amorphous to tetragonal phase on calcining at 700 °C for 1 h. Ball-milled BaTiO3 powder sintered to 97% relative density at 1200 °C after 2 h, with a grain size of approximately 200 nm. Ba2TiO4 powder required longer holding times or higher temperatures to be crystallized from the amorphous phase than did BaTiO3. In Ba2TiO4, the phase transformation between low-temperature monoclinic symmetry to high-temperature orthorhombic symmetry was observed by dilatometry and differential scanning calorimetry. A volume decrease of ∼0.5% accompanied the monoclinic-to-orthorhombic transformation on heating. The high-temperature orthorhombic phase could be retained down to room temperature y the addition of at least 6 wt% magnesia (MgO) stabilizer.

scholarly journals Demonstration of Phase Change Thermal Energy Storage in Zinc Oxide Microencapsulated Sodium Nitrate

2021 ◽  
Vol 11 (13) ◽  
pp. 6234
Author(s):  
Ciprian Neagoe ◽  
Ioan Albert Tudor ◽  
Cristina Florentina Ciobota ◽  
Cristian Bogdanescu ◽  
Paul Stanciu ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Thermal Properties ◽  
High Temperature ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Sodium Nitrate ◽  
Thermal Energy Storage ◽  
Metal Corrosion ◽  
Scanning Calorimetry

Microencapsulation of sodium nitrate (NaNO3) as phase change material for high temperature thermal energy storage aims to reduce costs related to metal corrosion in storage tanks. The goal of this work was to test in a prototype thermal energy storage tank (16.7 L internal volume) the thermal properties of NaNO3 microencapsulated in zinc oxide shells, and estimate the potential of NaNO3–ZnO microcapsules for thermal storage applications. A fast and scalable microencapsulation procedure was developed, a flow calorimetry method was adapted, and a template document created to perform tank thermal transfer simulation by the finite element method (FEM) was set in Microsoft Excel. Differential scanning calorimetry (DSC) and transient plane source (TPS) methods were used to measure, in small samples, the temperature dependency of melting/solidification heat, specific heat, and thermal conductivity of the NaNO3–ZnO microcapsules. Scanning electron microscopy (SEM) and chemical analysis demonstrated the stability of microcapsules over multiple tank charge–discharge cycles. The energy stored as latent heat is available for a temperature interval from 303 to 285 °C, corresponding to onset–offset for NaNO3 solidification. Charge–self-discharge experiments on the pilot tank showed that the amount of thermal energy stored in this interval largely corresponds to the NaNO3 content of the microcapsules; the high temperature energy density of microcapsules is estimated in the range from 145 to 179 MJ/m3. Comparison between real tank experiments and FEM simulations demonstrated that DSC and TPS laboratory measurements on microcapsule thermal properties may reliably be used to design applications for thermal energy storage.

scholarly journals Effects of Ni Additions on the High Temperature Expansion, Melting and Oxidation Behaviors of Cobalt-Based Superalloys

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 173
Author(s):  
Patrice Berthod ◽  
Lionel Aranda ◽  
Jean-Paul Gomis
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Mechanical Analysis ◽  
Scanning Calorimetry ◽  
Beneficial Effects ◽  
Ni Addition ◽  
High Temperature Expansion ◽  
High Fraction ◽  
Thermal Analysis Techniques ◽  
Ni Additions

Nickel is often added to cobalt-based superalloys to stabilize their austenitic structure. In this work the effects of Ni on several high temperature properties of a chromium-rich cobalt-based alloy reinforced by high fraction of TaC carbides are investigated. Different thermal analysis techniques are used: differential scanning calorimetry (DSC), thermo-mechanical analysis (TMA) and thermogravimetry (TG). Results show that the progressive addition of nickel did not induce great modifications of microstructure, refractoriness or thermal expansion. However, minor beneficial effects were noted, including reduction of the melting temperature range and slight decrease in thermal expansion coefficient. The most important improvement induced by Ni addition concerns the hot oxidation behavior. In this way, introducing several tens wt % Ni in this type of cobalt-based alloy may be recommended.

scholarly journals Tailoring Atomoxetine Release Rate from DLP 3D-Printed Tablets Using Artificial Neural Networks: Influence of Tablet Thickness and Drug Loading

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 111
Author(s):  
Gordana Stanojević ◽  
Djordje Medarević ◽  
Ivana Adamov ◽  
Nikola Pešić ◽  
Jovana Kovačević ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Release Rate ◽  
Drug Loading ◽  
Prolonged Release ◽  
Cylindrical Shape ◽  
Poly Ethylene Glycol ◽  
Scanning Calorimetry ◽  
3D Printed ◽  
Artificial Neural ◽  
Poly Ethylene

Various three-dimensional printing (3DP) technologies have been investigated so far in relation to their potential to produce customizable medicines and medical devices. The aim of this study was to examine the possibility of tailoring drug release rates from immediate to prolonged release by varying the tablet thickness and the drug loading, as well as to develop artificial neural network (ANN) predictive models for atomoxetine (ATH) release rate from DLP 3D-printed tablets. Photoreactive mixtures were comprised of poly(ethylene glycol) diacrylate (PEGDA) and poly(ethylene glycol) 400 in a constant ratio of 3:1, water, photoinitiator and ATH as a model drug whose content was varied from 5% to 20% (w/w). Designed 3D models of cylindrical shape tablets were of constant diameter, but different thickness. A series of tablets with doses ranging from 2.06 mg to 37.48 mg, exhibiting immediate- and modified-release profiles were successfully fabricated, confirming the potential of this technology in manufacturing dosage forms on demand, with the possibility to adjust the dose and release behavior by varying drug loading and dimensions of tablets. DSC (differential scanning calorimetry), XRPD (X-ray powder diffraction) and microscopic analysis showed that ATH remained in a crystalline form in tablets, while FTIR spectroscopy confirmed that no interactions occurred between ATH and polymers.

scholarly journals Improved high-temperature damping performance of nitrile-butadiene rubber/phenolic resin composites by introducing different hindered amine molecules

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 482-490
Author(s):  
Meng Song ◽  
Xiulin Yue ◽  
Xiujuan Wang ◽  
Mengjie Huang ◽  
Mingxing Ma ◽  
...  
Keyword(s):  
High Temperature ◽  
Phenolic Resin ◽  
Thermomechanical Analysis ◽  
Butadiene Rubber ◽  
Scanning Calorimetry ◽  
Nitrile Butadiene Rubber ◽  
Theoretical Support ◽  
Higher Temperature ◽  
Damping Materials ◽  
Hybrid Damping

AbstractBy introducing hindered amine GW-622 or GW-944 into nitrile-butadiene rubber/phenolic resin (NBR/PR, abbreviated as NBPR) matrix, we have prepared different hindered amine/NBR/PR ternary hybrid damping materials with high-temperature damping performance, respectively. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), differential scanning calorimetry (DSC), and dynamic thermomechanical analysis (DMA) were used to research the microstructure, compatibility, and damping properties of the hindered amine/NBPR composites. FTIR results indicate that hydrogen bonds are formed between the hindered amine and the NBPR matrix. Both DSC and SEM results show that hindered amine has partial compatibility with the NBPR matrix. DMA results show that two loss peaks appear in the hindered amine/NBPR composite. Thereby, the composites show better damping performance at a higher temperature, and the temperature domain of high-temperature damping becomes wider with the increase in the addition of hindered amine. This study provides a theoretical support for the preparation of high-temperature damping materials.

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