scholarly journals Analysis of the subsolidus structure in the Al2O3 – FeO – TiO2 system

2021 ◽  
pp. 45-50
Author(s):  
Oksana Borysenko ◽  
Sergey Logvinkov ◽  
Galina Shabanova
Keyword(s):  
Phase Composition ◽  
Composite Materials ◽  
Calculated Data ◽  
Small Degree ◽  
Large Area ◽  
Resource Saving ◽  
Temperature Range ◽  
Temperature Ranges ◽  
Synthesized Materials ◽  
Elementary Triangle

The study of the subsolidus structure of multicomponent systems for the synthesis of composite materials with specified phase composition and properties is urgent. Insufficient knowledge of the Al2O3 – FeO – TiO2 system arouses research interest in the structure of the system, as well as in the processes that occur in the system in different temperature ranges. A thermodynamic analysis of the Al2O3 – FeO – TiO2 system was carried out and it was found that the partition of the system into elementary triangles changes in five temperature ranges: I – up to a temperature of 1413 K, II – in the temperature range 1413 – 1537 K, III – 1537 – 1630 K, IV – 1630 – 2076 K and V – above the temperature of 2076 K. The main geometrical-topological characteristics of the subsolidus structure of the system and its phases were analyzed: the areas of elementary triangles, the degree of their asymmetry, the area of regions in which phases exist and the probability of the existence of phases. It was found that the FeAl2O4 – Fe2TiO4 – FeO elementary triangle with a relatively large area and a fairly small degree of asymmetry remained unchanged up to a temperature of 2076 K and the FeAl2O4 phase had the highest probability of existence above a temperature of 1413 K; all this indicates the reliability of predicting the phase composition of synthesized materials in this area and does not require special technological conditions for the accuracy of dosing and the time for homogenization of precursors. In the temperature range 1537 – 1630 К, the Al2TiO5 – FeAl2O4 – TiO2 elementary triangle has the largest area, but rearrangement of the connections occurs above a temperature of 1630 K. In this range, researchers may be interested in the FeTi2O5 – Al2TiO5 – FeTiO3 elementary triangle, which has the smallest area and the greatest degree of asymmetry. Of course, it is possible to perform additional calculations to determine whether the compositions belong to the joint area of two elementary triangles Al2TiO5 – FeAl2O4 – TiO2 and FeTi2O5 – Al2TiO5 – FeTiO3, special technological methods of mass preparation and synthesis must be strictly observed in working in this area. For corundum refractories and corundum-based materials with increased heat resistance, it is advisable to calculate whether the compositions belong to the joint region Al2O3 – Al2TiO5 – FeAl2O4 (in the temperature range 1537 – 1630 K) and Al2TiO5 – FeTiO3 – Al2O3 or FeTiO3 – Al2O3 – FeAl2O4 (above a temperature of 1630 K). The calculated data obtained above a temperature of 2076 K, as a consequence of non-proving the existence of the Al4TiO8 compound, are of recommendatory nature and require further theoretical and practical studies. Based on the results obtained, recommendations are given on the range of compositions that are optimal for obtaining new materials with the required phase composition and desired properties. This will contribute to the development of the latest resource-saving technologies for the manufacture of composite materials.

Mechanochemical Synthesis of Hexagonal Ferrites BaFe12O19

2018 ◽  
Vol 781 ◽  
pp. 119-124 ◽  
Author(s):  
Viktor Zhuravlev ◽  
Anna Nevmyvaka ◽  
Volya Itin ◽  
Dmitry Velikanov
Keyword(s):  
Phase Composition ◽  
Saturation Magnetization ◽  
Mechanochemical Synthesis ◽  
Annealing Temperature ◽  
Structural Parameters ◽  
Anisotropy Field ◽  
Magnetic Characteristics ◽  
Hexagonal Ferrites ◽  
Increasing Temperature ◽  
Synthesized Materials

The phase composition, structural parameters, and basic magnetic characteristics of BaFe12O19 hexaferrites prepared by the mechanochemical synthesis with subsequent annealing at a temperature of 1000°С and 1100°С for 1 h are investigated. The influence of the annealing temperature on the properties of synthesized materials is analyzed. Values of the saturation magnetization and the anisotropy field are determined. It is established that annealing temperature in the interval 1000 - 1100 °C does not significantly affect on the phase composition and the size of nanoparticles. The value of the anisotropy field increases substantially with increasing temperature.

Corrosion Tests of Zircaloy Hull Waste to Confirm Applicability of Corrosion Model and to Evaluate Influence Factors on Corrosion Rate under Geological Disposal Conditions

2014 ◽  
Vol 1665 ◽  
pp. 195-202 ◽  
Author(s):  
Osamu Kato ◽  
Hiromi Tanabe ◽  
Tomofumi Sakuragi ◽  
Tsutomu Nishimura ◽  
Tsuyoshi Tateishi
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Pure Water ◽  
Influence Factors ◽  
Spent Fuel ◽  
Geological Disposal ◽  
Corrosion Tests ◽  
Temperature Range ◽  
Corrosion Rates ◽  
Temperature Ranges

ABSTRACTCorrosion behavior is a key issue in the assessment of disposal performance for activated waste such as spent fuel assemblies (i.e., hulls and end-pieces) because corrosion is expected to initiate radionuclide (e.g., C-14) leaching from such waste. Because the anticipated corrosion rate is extremely low, understanding and modeling Zircaloy (Zry) corrosion behavior under geological disposal conditions is important in predicting very long-term corrosion. Corrosion models applicable in the higher temperature ranges of nuclear reactors have been proposed based on considerable testing in the 523−633 K temperature range.In this study, corrosion tests were carried out to confirm the applicability of such existing models to the low temperature range of geological disposal, and to examine the influence of material, environmental, and other factors on corrosion rates under geological disposal conditions. A characterization analysis of the generated oxide film was also performed.To confirm applicability, the corrosion rate of Zry-4 in pure water with a temperature change from 303 K to 433 K was obtained using a hydrogen measuring technique, giving a corrosion rate for 180 days of 8 × 10-3 μm/y at 303 K.To investigate the influence of various factors, corrosion tests were carried out. The corrosion rates for Zry-2 and Zry-4 were almost same, and increased with a temperature increase from 303 K to 353 K. The influence of pH (12.5) compared with pure water was about 1.4 at 180 days at 303 K.

scholarly journals Preparation and Characterization of Polymer Composite Materials Containing Magnetite

2021 ◽  
Vol 15 ◽  
pp. 1421-1428
Author(s):  
E. R. Sadretdinova ◽  
Thant Zin Hein
Keyword(s):  
Electron Microscopy ◽  
Phase Composition ◽  
Composite Materials ◽  
Ir Spectroscopy ◽  
Polymer Processing ◽  
Flow State ◽  
Standard Methods ◽  
Composition And Structure ◽  
Polyethylene Melt

In this work, magnetite nanoparticles are introduced into a polyethylene melt at the stage of a viscous-flow state by standard methods of polymer processing (extrusion), which makes it possible to obtain a nanocomposite with a uniform nanofiller distribution. The phase composition and structure of the nanocomposite were confirmed by XRF, electron microscopy, and IR spectroscopy. It is shown that the preparation of Fe3O4/LLDPE nanocomposites is not complicated by the appearance of unidentified phases and changes in the structure of the polymer matrix.

Searching accurate predicted viscosities near the melting point in a non-strong glass-forming liquid

2020 ◽  
Vol 34 (26) ◽  
pp. 2050230
Author(s):  
Qian Gao ◽  
Zengyun Jian ◽  
Man Zhu ◽  
Yan Chen ◽  
Bo Dang ◽  
...  
Keyword(s):  
Melting Point ◽  
Measured Data ◽  
Viscosity Data ◽  
Temperature Range ◽  
Glass Forming ◽  
Temperature Ranges ◽  
Measured Viscosity

The accurate predicted viscosities near the melting point [Formula: see text] have been searched. In order to find the temperature ranges, where the measured viscosity data applied to obtain the accurate fitting viscosity data and the accurate fitting expressions near [Formula: see text] lie, the measured data in 15 different temperature ranges (a)–(o) are applied to obtain the fitting viscosity data and the fitting expressions by the Vogel–Fulcher–Tammann (VFT) relation. The accuracy of the fitting viscosity near [Formula: see text] will varies when the measured data in different temperature ranges are applied to obtain the fitting viscosity data by VFT relation. It is found that the accurate fitting viscosity data with the coefficients of determination [Formula: see text] in temperature range 397.3–583.6 K (0.84–1.24[Formula: see text]) near [Formula: see text] can be acquired using the measured data in temperature ranges (g)–(h) and (k) by the VFT relation. In other words, we found the temperature ranges (namely, temperature ranges (g)–(h) and (k)), in which the measured viscosity data applied to obtain the accurate fitting viscosity data and the accurate fitting expressions near [Formula: see text] exist.

The Hall Carrier Mobility of AgBiTe2-Ag2Te Composite

2001 ◽  
Vol 691 ◽  
Author(s):  
T. Sakakibara ◽  
Y. Takigawa ◽  
K. Kurosawa
Keyword(s):  
Electrical Conductivity ◽  
Composite Material ◽  
Composite Materials ◽  
Hall Coefficient ◽  
Carrier Mobility ◽  
Matrix Phase ◽  
Second Phase ◽  
Temperature Range ◽  
The Matrix ◽  
Van Der Pauw

ABSTRACTWe prepared a series of (AgBiTe2)1−x(Ag2Te)x(0≤×≤1) composite materials by melt and cool down [1]. The Hall coefficient and the electrical conductivity were measured by the standard van der Pauw technique over the temperature range from 93K to 283K from which the Hall carrier mobility was calculated. Ag2Te had the highest mobility while the mobility of AgBiTe2was the lowest of all samples at 283K. However the mobility of the (AgBiTe2)0.125(Ag2Te)0.875composite material was higher than the motility of Ag2Te below 243K. It seems that a small second phase dispersed in the matrix phase is effective against the increased mobility.

scholarly journals The influence of pressure on the spontaneous ignition of inflammable gas-air mixtures - IV—methane-, ethane-, and propane-air mixtures

1936 ◽  
Vol 154 (881) ◽  
pp. 95-112 ◽  
Keyword(s):  
Critical Pressure ◽  
Spontaneous Ignition ◽  
Lower Range ◽  
Experimental Conditions ◽  
Temperature Range ◽  
Limited Temperature ◽  
Tentative Hypothesis ◽  
Temperature Ranges ◽  
Higher Temperature ◽  
Temperature And Pressure

In previous papers the results of investigations into the influence of varying initial pressures up to 15-20 atmospheres on the spontaneous ignition of mixtures with air of butane, iso -butane, pentane, and hexane were described. On the attainment of a critical pressure, which varied both with the hydrocarbon concerned and the composition of its mixture with air, the ignition points were always found to fall sharply from a higher temperature range above 500°C to a lower range at about 300°C. At pressures just exceeding the critical transition pressures ignition occurred at first only within limited temperature ranges which widened and ultimately merged with increasing pressure. The striking relationship between the behaviours of the hydrocarbons referred to under the experimental conditions and their “knocking” propensities in an engine was also indicated. While the data available were inadequate for drawing any final con­clusion as to the character of the phenomena referred to, a tentative hypothesis was advanced that while ignition in the higher temperature range pertains mainly to the thermal decomponents of intermedially formed compounds, ignition in the lower system occurs when temperature and pressure conditions favour the survival and further oxidation of such bodies, particularly aldehydes.

The Effect of Heating on Phase Composition of the Cr3C2- Ti System Hard Alloys Fabricated by the Explosive Compaction of Powder Mixtures

2019 ◽  
Vol 945 ◽  
pp. 617-622 ◽  
Author(s):  
V.O. Kharlamov ◽  
Aleksandr Vasilevich Krokhalev ◽  
S.V. Kuz’min ◽  
V.I. Lysak
Keyword(s):  
Phase Composition ◽  
Chromium Carbide ◽  
Heating Temperature ◽  
Calculated Data ◽  
Fine Powder ◽  
Hard Alloys ◽  
Explosive Compaction ◽  
X Ray ◽  
Diffusion Layers ◽  
Equilibrium Phases

The article reports findings on theoretically-calculated data and experimental results obtained with scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy methods of the analysis of hard alloys produced by the explosive compaction of the Cr3C2 chromium carbide powders with titanium, first in the original condition and then after heating to 1200 °C. It was established that when heated to 600 °С the phase composition of hard alloys does not change and corresponds to the composition of the original components of the powder mixture. When the heating temperature was increased to 650 °С, new fine powder fractions emerged at the “chromium carbide – titanium” interface. At the temperature of 700 °С two separate diffusion layers emerged and grew in the opposite directions. Due to this growth the source phases in the alloy fully disappeared at 1200 °С and two equilibrium phases were formed.

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