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Jacek Szczerba - One of the best experts on this subject based on the ideXlab platform.
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study of the hydration of calcium zirconium Aluminate ca7zral6o18 blended with reactive alumina by calorimetry thermogravimetry and other methods
Journal of Thermal Analysis and Calorimetry, 2015Co-Authors: Dominika Madej, Jacek SzczerbaAbstract:The reactivities of hydratable alumina, calcium zirconium Aluminate and their binary mixtures were investigated by calorimetric method, X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), differential thermal/thermogravimetric analysis (DTA–TG) and scanning electron microscope observations. The rate of heat evolution illustrates only one distinct exothermic peak in the mixtures containing calcium zirconium Aluminate which corresponds the subsequent precipitation of hydrated material mainly in the form of amorphous CaO–Al2O3–H2O phases and crystalline C4AH19 occurs simultaneously after wetting of Ca7ZrAl6O18 grains. Nevertheless, coexistence of both unstable calcium Aluminate hydrates (CAH10, C2AH8, C4AH19) and thermodynamically more stable C3AH6 detected by FT-IR and DTA–TG in the paste cured at 20 °C may have originated in the thermally induced partial conversion reaction due to the considerable amount of heat generated by the Ca7ZrAl6O18 hydration. It is also found that curing temperature affected the hydration products formed in the hydration products of both Ca7ZrAl6O18 and Ca7ZrAl6O18/Al2O3 blends. Reactive alumina influences the hydration behavior of Ca7ZrAl6O18 facilitating the nucleation and growth of hydration products, causes characteristic changes in the microstructure of hardened blended pastes and favors recrystallization of dehydrated calcium Aluminates.
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phase transformation during the decomposition of hydrated calcium zirconium Aluminate ca7zral6o18 paste subjected to various dehydration temperatures
Thermochimica Acta, 2014Co-Authors: Dominika Madej, Jacek Szczerba, Krzysztof DulAbstract:Abstract In this paper, the results of experimental study concerning the characterization of dehydration behavior of the hydrated Ca7ZrAl6O18 phase are presented. The hydrated and dehydrated Ca7ZrAl6O18 pastes were investigated by DTA-TG-EGA, LT-XRD, HT-XRD, FT-IR, and SEM/EDS techniques. The original Ca7ZrAl6O18 changed to the calcium–Aluminate–hydrates (C–A–H; C CaO, A Al2O3, H H2O) and CaZrO3 due to the hydration reaction after mixing with water. C3AH6 was formed in the conversion reaction of metastable hexagonal hydrated phases, i.e., CAH10 and C2AH8 due to higher temperature. Calcium Aluminates, Ca3Al2O6, Ca12Al14O33, and Ca5Al6O14 were formed as dehydration products of C–A–H phases. The results of IR spectroscopic measurements revealed that pentacalcium triAluminate, Ca5Al6O14 has appeared as a preliminary amorphous calcium Aluminate phase. The unknown ternary compound in the system CaO–Al2O3–ZrO2 forming the dehydrated ring on the surface of the internal core of the unhydrated Ca7ZrAl6O18 grains has been identified by SEM-EDS.
Dominika Madej - One of the best experts on this subject based on the ideXlab platform.
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study of the hydration of calcium zirconium Aluminate ca7zral6o18 blended with reactive alumina by calorimetry thermogravimetry and other methods
Journal of Thermal Analysis and Calorimetry, 2015Co-Authors: Dominika Madej, Jacek SzczerbaAbstract:The reactivities of hydratable alumina, calcium zirconium Aluminate and their binary mixtures were investigated by calorimetric method, X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), differential thermal/thermogravimetric analysis (DTA–TG) and scanning electron microscope observations. The rate of heat evolution illustrates only one distinct exothermic peak in the mixtures containing calcium zirconium Aluminate which corresponds the subsequent precipitation of hydrated material mainly in the form of amorphous CaO–Al2O3–H2O phases and crystalline C4AH19 occurs simultaneously after wetting of Ca7ZrAl6O18 grains. Nevertheless, coexistence of both unstable calcium Aluminate hydrates (CAH10, C2AH8, C4AH19) and thermodynamically more stable C3AH6 detected by FT-IR and DTA–TG in the paste cured at 20 °C may have originated in the thermally induced partial conversion reaction due to the considerable amount of heat generated by the Ca7ZrAl6O18 hydration. It is also found that curing temperature affected the hydration products formed in the hydration products of both Ca7ZrAl6O18 and Ca7ZrAl6O18/Al2O3 blends. Reactive alumina influences the hydration behavior of Ca7ZrAl6O18 facilitating the nucleation and growth of hydration products, causes characteristic changes in the microstructure of hardened blended pastes and favors recrystallization of dehydrated calcium Aluminates.
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phase transformation during the decomposition of hydrated calcium zirconium Aluminate ca7zral6o18 paste subjected to various dehydration temperatures
Thermochimica Acta, 2014Co-Authors: Dominika Madej, Jacek Szczerba, Krzysztof DulAbstract:Abstract In this paper, the results of experimental study concerning the characterization of dehydration behavior of the hydrated Ca7ZrAl6O18 phase are presented. The hydrated and dehydrated Ca7ZrAl6O18 pastes were investigated by DTA-TG-EGA, LT-XRD, HT-XRD, FT-IR, and SEM/EDS techniques. The original Ca7ZrAl6O18 changed to the calcium–Aluminate–hydrates (C–A–H; C CaO, A Al2O3, H H2O) and CaZrO3 due to the hydration reaction after mixing with water. C3AH6 was formed in the conversion reaction of metastable hexagonal hydrated phases, i.e., CAH10 and C2AH8 due to higher temperature. Calcium Aluminates, Ca3Al2O6, Ca12Al14O33, and Ca5Al6O14 were formed as dehydration products of C–A–H phases. The results of IR spectroscopic measurements revealed that pentacalcium triAluminate, Ca5Al6O14 has appeared as a preliminary amorphous calcium Aluminate phase. The unknown ternary compound in the system CaO–Al2O3–ZrO2 forming the dehydrated ring on the surface of the internal core of the unhydrated Ca7ZrAl6O18 grains has been identified by SEM-EDS.
Lucia Fernandezcarrasco - One of the best experts on this subject based on the ideXlab platform.
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hydration of calcium Aluminates and calcium sulfoAluminate studied by raman spectroscopy
Cement and Concrete Research, 2013Co-Authors: David Torrensmartin, Lucia Fernandezcarrasco, S MartinezramirezAbstract:Abstract Raman spectroscopy has been used to follow the hydration of the main calcium Aluminate phases present in calcium Aluminate cement (CAC) and calcium sulfoAluminate cement (CSA) clinkers, i.e. C3A, CA, C12A7, CA2, C4AF and C4A3 S ¯ . We investigate the reaction products induced by hydration on these six compounds. Spectra of anhydrous pure samples and pastes hydrated for 48 h were recorded. In order to contrast the Raman analysis results, the samples were also characterized by XRD and FTIR techniques. Hydration of calcium Aluminates led to the formation of C3AH6, C2AH8 and aluminum hydroxide, and hydration of ferrite phases led to hydrogarnet phases. Meanwhile the hydration of C4A3 S ¯ led to the formation of ettringite and AFm phases. The Raman spectra analysis developed gives the details of the vibration of the different functional groups present in the calcium Aluminate hydrated samples and our results show the potential of Raman spectroscopy in the study of the Aluminate hydration on the cement chemistry. The product identity was confirmed by XRD and infrared spectroscopy.
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reactions of fly ash with calcium Aluminate cement and calcium sulphate
Fuel, 2009Co-Authors: Lucia Fernandezcarrasco, E VazquezAbstract:The hydration processes in the ternary system fly ash/calcium Aluminate cement/calcium sulphate (FA/CAC/C$) at 20 °C were investigated; six compositions from the ternary system FA/CAC/C$ were selected for this study. The nature of the reaction products in these pastes were analysed by X-ray diffraction (XRD) and infrared spectroscopy (FTIR). At four days reaction time, the main hydration reaction product in these pastes was ettringite and the samples with major initial CAC presented minor ettringite but calcium Aluminates hydrates. The amount of ettringite developed in the systems has no direct relation with the initial components.
Jose Ramon Gonzalez - One of the best experts on this subject based on the ideXlab platform.
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synthesis of calcium Aluminates from non saline aluminum dross
Materials, 2019Co-Authors: Felix A Lopez, M I Martin, Francisco Jose Alguacil, Mario Sergio Ramirez, Jose Ramon GonzalezAbstract:The present work examines the synthesis of tricalcium Aluminate (for use as a synthetic slag) from the non-saline dross produced in the manufacture of metallic aluminum in holding furnaces. Three types of input drosses were used with Al2O3 contents ranging from 58 to 82 wt %. Calcium Aluminates were formed via the mechanical activation (reactive milling) of different mixtures of dross and calcium carbonate, sintering at 1300 °C. The variables affecting the process, especially the milling time and the Al2O3/CaO molar ratio, were studied. The final products were examined via X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The reactive milling time used was 5 h in a ball mill, for a ball/dross mass ratio of 6.5. For a molar relationship of 1:3 (Al2O3/CaO), sintered products with calcium Aluminate contents of over 90% were obtained, in which tricalcium Aluminate (C3A) was the majority compound (87%), followed by C12A7 (5%).
Miguel A. Rodríguez - One of the best experts on this subject based on the ideXlab platform.
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new cement based on calcium and strontium Aluminates for endodontics
Ceramics International, 2019Co-Authors: Willams Teles Barbosa, Raul Garciacarrodeguas, Marcus Vinicius Lia Fook, Miguel A. RodríguezAbstract:Abstract Currently Mineral Trioxide Aggregate (MTA) is extensively used in Endodontics for Root Canal Treatment. It mainly consists of Portland cement and radio-opacifier agent. In spite of being widely used with success, there are some concerns regarding its properties. The objective of this study was to employ strontium and calcium Aluminates to formulate cement pastes with adequate physicochemical and biological properties that overwhelm the handicaps of current Mineral Trioxide Aggregate formulations. First, the desired crystalline phases of calcium and strontium Aluminates, i.e. dodeca-calcium hepta-Aluminate (Ca 12 Al 14 O 33 ), C 12 A 7, and tri-strontium Aluminate (S 3 Al 2 O 6 ), S ˇ 3 A , were obtained by Solution Combustion Synthesis and characterized. Then, they were used to formulate different cement compositions varying the wt.-% ratio of C 12 A 7 and S ˇ 3 A (100–0, 80–20, 60–40, 40–60, 20–80, and 0–100) which were characterized with regard to radiopacity. Equivalent radiopacities of 3.1- and 6.0-mm Al were obtained for the cements containing 80- and 100 wt.-% of S ˇ 3 A , both compliant with the requirement of the standard ISO 6876–2012. The cement with 80% of S ˇ 3 A was selected for further studies. Pastes with additions of polyethylene glycol to the mixing liquid (0, 20, 30, and 40 wt.-%) were prepared and studied for workability, setting time, maximum temperature during setting and compressive strength. The cement paste prepared with 30 wt.-% of polyethylene glycol in the mixing liquid (Liquid/Powder 0.39 mL/g) presented good workability, maximum temperature of 33.5 °C, setting time of 60 min, significantly shorter than reported for MTA (140–175 min), and reached highest strength (10.5 MPa) 3 days after mixing. Cement discs were completely coated with a dense apatite layer after 7 days of immersion in simulated body fluid (SBF). The new cement might find application as root canal filler in Endodontics.
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Role of the oxidizing agent to complete the synthesis of strontium Aluminate based phosphors by the combustion method
RSC Advances, 2015Co-Authors: Rocío Estefanía Rojas-hernandez, Miguel A. Rodríguez, J.f. FernándezAbstract:The influence of processing parameters on the phase formation of strontium Aluminates doped with Eu2+ and Dy3+ by the combustion method has been evaluated. The addition of a slight excess of urea as a fuel has an important effect on the phase formation, but a larger amount of urea inhibited the strontium incorporation into the stuffed tridymite-like structure. The experimental results show that it is possible to incorporate a larger amount of urea than the theoretical one by adding nitric acid as an oxidizing agent. The presence of an oxidizing agent promotes both effective chelation of the cations and a higher crystalline order on strontium Aluminate. Nanostructured lamellar particles have been obtained in a single step and the particles are well crystallized. The combustion method avoids the standard requirements of post-thermal treatments in a reducing atmosphere to promote the appearance of Eu2+ cations. A higher amount of urea in the presence of the oxidizing agent produces strontium Aluminate particles with higher phosphorescence brightness, owing to the increase of the reduction process Eu3+ to Eu2+. The luminescence properties correlate with the crystallite size of the strontium Aluminate. The results demonstrate a pathway to obtain phosphorescent pigments with sizes down to 10 μm.