THERMAL INVESTIGATION OF SiO2-Bi2O3 HEAVY METAL GLASSES

2005 ◽  
Vol 19 (20) ◽  
pp. 3293-3299 ◽  
Author(s):  
V. SIMON ◽  
M. TODEA ◽  
S. SIMON
Keyword(s):  
Thermal Analysis ◽  
Heavy Metal ◽  
Differential Thermal Analysis ◽  
Silicon Dioxide ◽  
Melting Temperature ◽  
Structural Relaxation ◽  
Structural Changes ◽  
Glass Stability ◽  
Thermal Investigation ◽  
Metal Glasses

Structural changes induced by temperature rising in binary silico-bismuthate glasses are investigated by differential thermal analysis. Several exothermic peaks are recorded for all samples. Progressive substitution of Bi 2 O 3 by SiO 2 contributes to the structural relaxation of vitreous network and leads to diminishing of the melting temperature, even as SiO 2 content reaches 40 mol%. Glass stability is enhanced by addition of silicon dioxide.

Properties of SnO-B2O3-SiO2 Lead-Free Glass Powder

2011 ◽  
Vol 412 ◽  
pp. 133-137 ◽  
Author(s):  
Hua Zhu ◽  
Guo You Gan ◽  
Ji Kang Yan ◽  
Jin Hong Du ◽  
Jian Hong Yi ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Heavy Metal ◽  
Differential Thermal Analysis ◽  
Glass Transition ◽  
Glass Powder ◽  
Lead Free ◽  
Prepared Glass ◽  
Excellent Chemical ◽  
Temperature Melting ◽  
Free Glass

SnO-B2O3-SiO2 glass powders, in which the different contents of SnO and B2O3 were 35% ~ 70%wt and 26% ~ 61% wt respectively, were prepared through high-temperature melting, water quenching and Ball milling. XRD showed that the performance of forming glass was very good and the range of extension was very wide. The effect of the contents of SnO and B2O3 on Tg, acidoresistant and density of prepared glass was studied. IR showed that it generates the heavy metal oxide generated glass. The density of glass powder decrease with increase of B2O3 content, but increase with increasing SnO content. SnO-B2O3-SiO2 glass had excellent chemical stability. Differential thermal analysis (DTA) shown that, with increasing SnO content, glass transition temperature first lower and then decreased.

About Thermostability of Fe-Ni-P Amorphous Alloys

2012 ◽  
Vol 188 ◽  
pp. 21-26
Author(s):  
Aurel Raduta ◽  
Mircea Nicoară ◽  
Cosmin Locovei
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Amorphous Alloys ◽  
Structural Changes ◽  
P System ◽  
X Rays ◽  
Heating Rates ◽  
Planar Flow Casting ◽  
Activation Energy Of Crystallization

A research program has been completed in order to analyze structural changes during heating of amorphous alloys belonging to Fe-Ni-P system. Special attention has been given to thermodynamics and mechanism of crystallization, to determine some aspects of development for crystalline phases. Experimental material used to determine characteristics of crystallization consisted in long ribbons, 30 thick and 18 mm wide, fabricated by mean of “Planar Flow casting” as amorphous Fe42Ni38P16B4alloy. Differential Thermal Analysis (DTA) and X-rays diffraction have been used to determine crystallization temperature of this alloy. Curves of differential thermal analysis for heating rates ranging between 1°C/minute and 20 °C/minute have been used to determine activation energy of crystallization.

ADSORPTION OF CYCLOHEXANE AND BENZENE ON MIXED HYDROXIDES AND OXIDES OF MAGNESIUM AND ALUMINIUM

1966 ◽  
Vol 44 (8) ◽  
pp. 877-884 ◽  
Author(s):  
R. I. Razouk ◽  
Sh. Nashed ◽  
F. N. Antonious
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Thermogravimetric Analysis ◽  
Surface Area ◽  
Structural Changes ◽  
Mixed Oxides ◽  
X Ray Diffraction ◽  
Oxide Systems ◽  
X Ray ◽  
Characteristic Lines

Seven mixed hydroxides of magnesium and aluminium were prepared, and phase and structural changes accompanying their dehydration were investigated by differential thermal analysis, thermogravimetric analysis, and X-ray diffraction techniques. The differential thermal analysis curves possess 2 peaks corresponding to those of parent hydroxides together with a new peak, and the thermogravimetric analysis curves show slight inflections. X-ray diffraction patterns of the mixed hydroxides possess the characteristic lines of the parent hydroxides together with three to five new intense lines which might indicate the formation of a double hydroxide. When the mixed hydroxides are progressively heated they give rise to products possessing patterns which first become diffuse and ultimately pass mainly into the spinel pattern.Adsorption isotherms of cyclohexane and benzene were measured on the mixed hydroxides and their dehydration products. Specific surface areas calculated by the application of the Brunauer, Emmett, Teller (B.E.T.) equation are in general in good agreement for the two adsorbates. The surface area increases with rise of dehydration temperature to a maximum at 500–600 °C and then decreases with further rise in temperature. This behavior is common to crystalline oxide systems and may be ascribed to the intermingling of decomposition, re-crystallization, and sintering processes. Variations in the molecular ratio of the mixed oxides (as much as 20-fold), and in the method of preparation, do not much alter the surface area.

Synthesis of Nanocrystalline Fe25Al57.5Ni17.5 by Mechanical Alloying

2012 ◽  
Vol 476-478 ◽  
pp. 1318-1321
Author(s):  
Qi Zhi Cao ◽  
Jing Zhang
Keyword(s):  
Thermal Analysis ◽  
Solid Solution ◽  
Differential Thermal Analysis ◽  
Mechanical Alloying ◽  
Ball Mill ◽  
Structural Changes ◽  
Early Stage ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray

Nanostructured Fe25Al57.5Ni17.5intermetallics was prepared directly by mechanical alloying (MA) in a high-energy planetary ball-mill. The phase transformations and structural changes occurring in the studied material during mechanical alloying were investigated by X-ray diffraction (XRD). Thermal behavior of the milled powders was examined by differential thermal analysis (DTA). Disordered Al(Fe,Ni) solid solution was formed at the early stage. After 50 h of milling, Al(Fe,Ni) solid solution transformed into Al3Ni2，AlFe3，AlFe0.23Ni0.77 phase. The power annealed at temperature 500 results in forming of intermetallics AlFe3 and FeNi3 after 5h milling. The nanocrystalline intermetallic compound was obtained after 500h milling.

scholarly journals Study of the Effect of Cooling Rate on Eutectic Modification in A356 Aluminium Alloys

2013 ◽  
Vol 765 ◽  
pp. 130-134 ◽  
Author(s):  
Deni Ferdian ◽  
Jacques Lacaze ◽  
Ibon Lizarralde ◽  
Andrea Niklas ◽  
Ana Isabel Fernandez-Calvo
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Cooling Rate ◽  
Melting Temperature ◽  
Aluminium Alloys ◽  
A356 Alloy ◽  
Cooling Curves ◽  
Eutectic Melting ◽  
Cooling Rates ◽  
Eutectic Modification

In this present work, an assessment of eutectic modification based on thermal analysis was performed on modified A356 alloy. The effect of various cooling rates which were achieved by means of casting samples with various moduli in sand and metallic moulds was investigated. Cooling curves recorded from thermocouples inserted in the centre of the samples showed characteristic undercooling and recalescence associated with (Al)-Si eutectic modification. The results showed that cooling rate has a role in observed modification level. Furthermore, differential thermal analysis was included to determine the eutectic melting temperature.

Structural, Optical and Thermal Characterizations of Lithium Borate Glasses Containing the Barite

2019 ◽  
Vol 397 ◽  
pp. 24-38 ◽  
Author(s):  
K. Abdellaoui ◽  
I.Z. Hager ◽  
Hosam A. Othman ◽  
A. Boumaza ◽  
Najoua Kamoun
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Glass Transition ◽  
Structural Changes ◽  
Borate Glasses ◽  
Lithium Borate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amorphous Nature ◽  
F Center

A glass system was prepared according to the formula 60mol%B2O3 – x mol %barite – (40-x) mol %Li2O, where x=0, 5, 7.5, 10, 15 and 20 mol%. The amorphous nature of the prepared glasses was confirmed through X-ray diffraction. The prepared glasses were also characterized by FTIR spectroscopy, UV-vis absorption spectroscopy and the differential thermal analysis (DTA). The density is found to increase and this is because of the higher molecular of the added barite. The molar volume also increases with increasing barite content that indicates the structural changes occurred in borate network that were also confirmed using FTIR. Increasing the concentration of barite shifts the UV cutoff edge toward higher wavelengths from about 300 nm at 0 mol% barite to about 400 nm at 15 mol% of barite. Glass transition temperature (Tg) is found to increase with the increasing barite content. When analyzed by photoluminescence, the samples exhibit luminescence emission centered at around 400, 415, 480, 430, 485, 520, 545, and 570 nm when excited at 300 nm wavelength. The emission peaks at 420 nm, and 440 nm were assigned to F center emission. Between 440 nm and 520 nm it is rather the effect of the presence of the impurities.

DTA/TGA Study of Eutectic Melting in the System BaF2-BaO-Y2O3-CuOx−H2O

2000 ◽  
Vol 659 ◽  
Author(s):  
Lawrence P. Cook ◽  
Winnie Wong-Ng ◽  
Julia Suh
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Thermogravimetric Analysis ◽  
Melting Temperature ◽  
Coated Conductors ◽  
Ex Situ ◽  
Log P ◽  
Eutectic Melting ◽  
Melting Temperatures ◽  
C 30

ABSTRACTDifferential thermal analysis and thermogravimetric analysis (DTA/TGA) experiments have been completed in the BaF2-BaO-Y2O3-CuOx-H2O system at various oxygen pressures to determine the effect of adding solid BaF2and gaseous H2O (at pH2O = 2.5 kPa) on the eutectic melting in the system BaO-Y2O3-CuOx. We have investigated the eutectic melting temperature over the range of pO2 = 20 Pa to pO2 = 0.1 MPa under the following conditions: 1) without BaF2 or H2O; 2) with H2O only; 3) with BaF2 only; 4) with both BaF2 and H2O. Results indicate that without BaF2 or H2O, eutectic melting is depressed from 917°C at pO2 = 0.1 MPa to 838°C at pO2 = 1 kPa. At oxygen pressures below 1 kPa, down to pO2 = 20 Pa, no further lowering of eutectic melting temperature was observed. The topologies of the temperature vs. log pO2 curves for various combinations of BaF2 and H2O were similar to that for the experiments without BaF2 or H2O, but all curves were shifted to lower temperatures. For the experiments with addition of BaF2 only, H2O only, and BaF2 with H2O, the eutectic melting temperatures as a function of pO2 were lowered by, respectively, 5°C - 15°C, 15°C - 25°C and 20°C - 30°C. Application of results to the “BaF2ex-situ” method of processing Ba2YCu3Ox coated conductors is discussed.

Diagramme de phases du système K–K2O et le monooxyde de potassium K2O

1970 ◽  
Vol 48 (13) ◽  
pp. 1955-1958 ◽  
Author(s):  
F. Natola ◽  
Ph. Touzain
Keyword(s):  
Thermal Analysis ◽  
Phase Diagram ◽  
Differential Thermal Analysis ◽  
Melting Temperature ◽  
Lower Oxide ◽  
Reversible Transitions

Le diagramme de fusion du système K–K2O est obtenu par la technique de l'analyse thermique différentielle. La fusion du monooxyde de potassium K2O se manifeste à 646 + 5 °C. Des transformations cristallines réversibles de l'oxyde sont observées à 317, 372 et 446 °C. La dismutation de l'oxyde en peroxyde et métal apparait à une température approximativement égale à celle de la dernière des transitions. Le diagramme K–K2O comporte un eutectique à une température très proche de la température de fusion du potassium et une monotectie à 600 °C (concentration monotectique: 30.5 % atomique d'oxygène). Aucune existence de sous-oxyde n'est démontrée.The potassium–oxygen phase diagram has been determined up to the composition of K2O by the technique of differential thermal analysis. Potassium monoxide K2O melts at 646 ± 5 °C. Reversible transitions occur in solid K2O at 317, 372, and 446 °C. Disproportion of the monoxide into the peroxide and metal occurs at a temperature identical or very near to that of the last transition. The K–K2O eutectic melts at a temperature very close to the melting temperature of pure K (degenerate eutectic) and the monotectic at 600 °C (monotectic concentration: 30.5 oxygen atomic %). No evidence has been obtained that would indicate the existence of a lower oxide.

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