Synthesis and thermal properties of the nanoand macro-crystalline Bi5FeTi3O15 ceramic materials

2018 ◽  
pp. 29-33 ◽  
Author(s):  
N. A. Lomanova
Keyword(s):  
Phase Transition ◽  
Thermal Properties ◽  
Phase Composition ◽  
Linear Expansion ◽  
Ceramic Materials ◽  
Thermal Coefficient ◽  
Surface Phase ◽  
Aurivillius Phase ◽  
Synthesis Conditions ◽  
Sintering Characteristics

The synthesis conditions' influence on the development, thermal behavior, and sintering characteristics was investigated for the nanoand macro-crystalline Bi5FeTi3O15 ceramic materials which had the structure of the perovskite-like four-layered Aurivillius phase. It was shown that the beginning of grains sintering is consistent with the beginning of the surface phase melting, given that the surface phase composition can be governed by the initial mixture's chemical composition changing. The temperatures of crystallization, phase transition, decomposition, sintering activation were defined, as well as the thermal coefficient of the linear expansion of the produced materials was determined.

The Effect of Phase Composition on the Mechanical and Thermal Properties of LTCC Material

2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000492-000497
Author(s):  
Kostja Makarovič ◽  
Anton Meden ◽  
Marko Hrovat ◽  
Janez Holc ◽  
Andreja Benčan ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Phase Composition ◽  
Flexural Strength ◽  
Mass Fraction ◽  
Major Change ◽  
Multilayer Structures ◽  
Propagation Mechanism ◽  
Mechanical And Thermal Properties ◽  
Thermal Coefficient ◽  
Biaxial Flexural Strength

Low-temperature co-fired ceramic (LTCC) is an important material in the production of ceramic multilayer structures. Large and complex multilayer structures are usually fired at higher temperatures and/or longer firing times compared to the relatively thin LTCC tapes. The firing conditions of LTCC determine the phase composition and the microstructure, which both influence the physical characteristics, such as the mechanical and thermal properties. In this work the effect of the phase composition on the biaxial flexural strength and the temperature coefficient of expansion of the DuPont 951 LTCC is presented. The samples were fired at different temperatures and times to obtain different phase compositions. The phase composition, especially the mass fraction of anorthite, was correlated with the biaxial flexural strength and the thermal coefficient of expansion (TCE). A very long firing time, i.e., 100h at 800 °C, yields, apart from crystalline anorthite, the cristobalite phase. The anorthite that crystalizes from the glass phase in a dense LTCC material changes the crack-propagation mechanism and improves the biaxial flexural strength of the material. The major change in the biaxial flexural strength is observed when the anorthite phase appeared. The increasing mass fraction of anorthite does improve the biaxial flexural strength less drastically. With the increasing mass fraction of the anorthite, decreases of the TCE of the material and a small decrease of the density of the LTCC material occur.

scholarly journals Investigation of the thermal properties of mullite-cordierite materials

2018 ◽  
Vol 118 ◽  
pp. 111-118
Author(s):  
О. V. Savvova ◽  
O. I. Fesenko ◽  
V. D. Timofeеv ◽  
Ya. V. Poviderna
Keyword(s):  
Heat Treatment ◽  
Thermal Properties ◽  
Fire Resistance ◽  
Glass Ceramic ◽  
Linear Expansion ◽  
High Strength ◽  
Ceramic Materials ◽  
Glass Ceramic Materials ◽  
Cordierite Glass ◽  
Coefficient Of Linear Expansion

Based on the analysis of existing mullite-cordierite sitalls, the need to create high-strength materials of this type for individual and local protection against high-speed loads has been determined. They should be characterized by lower cost, due to low-temperature short-term heat treatment using domestic raw materials. An important aspect of ensuring the effective protective effect of an armor-element, in addition to its armor resistance and survivability, is the ability to withstand the effects of open flame and combustible mixtures, which is determined by the thermal properties of the sitalls. The aim of this work is to study the thermal properties, namely thermal expansion coefficient and fire resistance, high strength mullite-cordierite glass-ceramics that they are developed by us earlier. The temperature coefficient of linear expansion was determined using a quartz vertical dilatometer QVD-5A (ASTM C 372-94 (2007)), fire resistance according to GOST 33000—2014. According to X-ray diffraction and differential thermal analyzes, the experimental samples were divided into two groups according to the formation mechanism of structure and phase composition of glass materials during heat treatment. For each of the materials groups, the influence of the chemical and phase compositions on the thermal coefficient of linear expansion of the original mullite-cordierite glass materials and glass-ceramic materials (sitalls) thermally treated using two-stage heat treatment was determined. The study of the fire resistance of the developed glass-ceramic materials made it possible to establish that they withstand the thermal load in a certain mode for 360 minutes. It has been established that providing high thermal- and fire resistance (RE 360 (h)) is a determining factor in the production of hardened glass crystalline materials that are able to resist to thermal destroying at sharp temperature change.

scholarly journals Phase Transition and Coefficients of Thermal Expansion in Al2−xInxW3O12 (0.2 ≤ x ≤ 1)

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4021
Author(s):  
Andrés Esteban Cerón Cerón Cortés ◽  
Anja Dosen ◽  
Victoria L. Blair ◽  
Michel B. Johnson ◽  
Mary Anne White ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Thermal Shock ◽  
Monoclinic Phase ◽  
Ceramic Materials ◽  
Precipitation Method ◽  
Scanning Calorimetry ◽  
Orthorhombic Crystal ◽  
Co Precipitation

Materials from theA2M3O12 family are known for their extensive chemical versatility while preserving the polyhedral-corner-shared orthorhombic crystal system, as well as for their consequent unusual thermal expansion, varying from negative and near-zero to slightly positive. The rarest are near-zero thermal expansion materials, which are of paramount importance in thermal shock resistance applications. Ceramic materials with chemistry Al2−xInxW3O12 (x = 0.2–1.0) were synthesized using a modified reverse-strike co-precipitation method and prepared into solid specimens using traditional ceramic sintering. The resulting materials were characterized by X-ray powder diffraction (ambient and in situ high temperatures), differential scanning calorimetry and dilatometry to delineate thermal expansion, phase transitions and crystal structures. It was found that the x = 0.2 composition had the lowest thermal expansion, 1.88 × 10−6 K−1, which was still higher than the end member Al2W3O12 for the chemical series. Furthermore, the AlInW3O12 was monoclinic phase at room temperature and transformed to the orthorhombic form at ca. 200 °C, in contrast with previous reports. Interestingly, the x = 0.2, x = 0.4 and x = 0.7 materials did not exhibit the expected orthorhombic-to-monoclinic phase transition as observed for the other compositions, and hence did not follow the expected Vegard-like relationship associated with the electronegativity rule. Overall, compositions within the Al2−xInxW3O12 family should not be considered candidates for high thermal shock applications that would require near-zero thermal expansion properties.

Photoelectron diffraction and photoelectron holography study of a Ge(111) high-temperature surface phase transition

1993 ◽  
Vol 281 (3) ◽  
pp. 178-179
Author(s):  
T.T. Tran ◽  
S. Thevuthasan ◽  
Y.J. Kim ◽  
D.J. Friedman ◽  
A.P. Kaduwela ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Surface Phase ◽  
Surface Phase Transition ◽  
Photoelectron Diffraction ◽  
Temperature Surface

Particle anisotropy and crystalline phase transition in one-pot synthesis of nano-zirconia: a causal relationship

CrystEngComm ◽  
2018 ◽  
Vol 20 (7) ◽  
pp. 879-888 ◽  
Author(s):  
Francesca Tana ◽  
Andrea Serafini ◽  
Luca Lutterotti ◽  
Alberto Cigada ◽  
Fabio Variola ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Composition ◽  
Causal Relationship ◽  
Crystalline Phase ◽  
One Pot ◽  
One Pot Synthesis ◽  
Nanocrystal Growth ◽  
Particle Anisotropy ◽  
Morphological Transformations ◽  
Crystalline Phase Transition

The effects of experimental variables on zirconia nanocrystal growth are investigated, correlating the morphological transformations with phase composition in synthesized nanopowders.

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