Thermal Expansion of Glass-Forming Zr-based Alloys in the Melt, the Undercooled Liquid and the Different Solid States

2000 ◽  
Vol 644 ◽  
Author(s):  
K. Samwer ◽  
B. Damaschke ◽  
M. Krause ◽  
P. Ryder
Keyword(s):  
Thermal Expansion ◽  
Ccd Camera ◽  
Electromagnetic Levitation ◽  
High Reactivity ◽  
Undercooled Liquid ◽  
Thermal Expansion Data ◽  
Glass Forming ◽  
Thermal Expansion Coefficients ◽  
Free Volume Model ◽  
Microgravity Conditions

AbstractThe thermal expansion coefficients of glass-forming Zr-based alloys were measured in the melt, the undercooled liquid and the glassy/crystalline state. Due to the high reactivity of the liquid material the experiments were performed containerlessly in an electrostatic levitator. We used an optical method where the samples were imaged with a high-resolution CCD- camera and the volume of the samples was evaluated by digital image processing. The coefficients of thermal expansion in the liquid and in the solid state could be determined from the volume versus temperature curves. The results can be compared with measurements in the electromagnetic levitation facility TEMPUS performed under microgravity conditions in the mission MSL-1 and ground based DMA-measurements. The thermal expansion data can be interpreted in terms of the free volume model.

An extended criterion for estimation of glass-forming ability of metals

2007 ◽  
Vol 22 (5) ◽  
pp. 1378-1383 ◽  
Author(s):  
Dmitri V. Louzguine-Luzgin ◽  
Akihisa Inoue
Keyword(s):  
Thermal Expansion ◽  
Specific Volume ◽  
Intersection Point ◽  
Glass Forming Ability ◽  
Molten Metals ◽  
Metallic Liquid ◽  
Glass Forming ◽  
Thermal Expansion Coefficients ◽  
Pure Metals ◽  
Expansion Coefficients

If a metal contracts upon solidification, the specific volume of a metallic liquid phase must not be smaller than that of the corresponding crystal. As molten metals have higher thermal expansion coefficients compared with those of the corresponding crystals, the intersection point of two specific-volume–temperature plots of the liquid and the corresponding solid crystalline phase by analogy with Kauzmann’s paradox for entropy could be treated as an ideal glass-transition temperature. This paper describes this phenomenon observed for a number of pure metals and gives a semiempirical criterion for the achievement of a good glass-forming ability.

Transformation behavior of yttria stabilized tetragonal zirconia polycrystal–TiB2 composites

2001 ◽  
Vol 16 (7) ◽  
pp. 2158-2169 ◽  
Author(s):  
B. Basu ◽  
J. Vleugels ◽  
O. Van Der Biest
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Low Temperature ◽  
Tetragonal Zirconia ◽  
Mechanical Analysis ◽  
Transformation Behavior ◽  
Thermal Expansion Data ◽  
Thermally Induced ◽  
First Time ◽  
Tetragonal Zirconia Polycrystal

The objective of the present article is to study the influence of TiB2 addition on the transformation behavior of yttria stabilized tetragonal zirconia polycrystals (Y-TZP). A range of TZP(Y)–TiB2 composites with different zirconia starting powder grades and TiB2 phase contents (up to 50 vol%) were processed by the hot-pressing route. Thermal expansion data, as obtained by thermo-mechanical analysis were used to assess the ZrO2 phase transformation in the composites. The thermal expansion hysteresis of the transformable ceramics provides information concerning the transformation behavior in the temperature range of the martensitic transformation and the low-temperature degradation. Furthermore, the transformation behavior and susceptibility to low-temperature degradation during thermal cycling were characterized in terms of the overall amount and distribution of the yttria stabilizer, zirconia grain size, possible dissolution of TiB2 phase, and the amount of residual stress generated in the Y-TZP matrix due to the addition of titanium diboride particles. For the first time, it is demonstrated in the present work that the thermally induced phase transformation of tetragonal zirconia in the Y-TZP composites can be controlled by the intentional addition of the monoclinic zirconia particles into the 3Y-TZP matrix.

Influence of Cr deficiency on sintering, thermal expansion and electrical properties of La0.75Sr0.25Cr1−xO3−δ as a SOFC interconnect material

2016 ◽  
Vol 30 (11) ◽  
pp. 1650127 ◽  
Author(s):  
Yi Ren ◽  
Wen Ma ◽  
Xiaoying Li ◽  
Jun Wang ◽  
Yu Bai ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Electrical Properties ◽  
Perovskite Phase ◽  
Ignition Process ◽  
Thermal Expansion Coefficients ◽  
Auto Ignition ◽  
Pure Perovskite Phase ◽  
Maximum Conductivity ◽  
Expansion Coefficients ◽  
Interconnect Material

The SOFC interconnect materials La[Formula: see text]Sr[Formula: see text]Cr[Formula: see text]O[Formula: see text] [Formula: see text]–[Formula: see text] were prepared using an auto-ignition process. The influences of Cr deficiency on their sintering, thermal expansion and electrical properties were investigated. All the samples were pure perovskite phase after sintering at 1400[Formula: see text]C for 4 h. The cell volume of La[Formula: see text]Sr[Formula: see text]Cr[Formula: see text]O[Formula: see text] decreased with increasing Cr deficient content. The relative density of the sintered bulk samples increased from 93.2% [Formula: see text] to a maximum value of 94.7% [Formula: see text] and then decreased to 87.7% [Formula: see text]. The thermal expansion coefficients of the sintered bulk samples were in the range of [Formula: see text]–[Formula: see text] (30–1000[Formula: see text]C), which are compatible with that of YSZ. Among the investigated samples, the sample with 0.02 Cr deficiency had a maximum conductivity of 40.4 Scm[Formula: see text] and the lowest Seebeck coefficient of 154.8 [Formula: see text]VK[Formula: see text] at 850[Formula: see text]C in pure He. The experimental results indicate that La[Formula: see text]Sr[Formula: see text]Cr[Formula: see text]O[Formula: see text] has the best properties and is much suitable for SOFC interconnect material application.

Novel Silicon-Elastomers for Advanced Soft Lithography

2006 ◽  
Vol 947 ◽  
Author(s):  
Kyung Choi
Keyword(s):  
Thermal Expansion ◽  
High Resolution ◽  
Soft Lithography ◽  
Materials Properties ◽  
Nano Scale ◽  
Thermal Expansion Coefficients ◽  
High Thermal Expansion ◽  
Expansion Coefficients

ABSTRACTHigh resolution pattern transfers in the nano-scale regime have been considerable challenges in ‘soft lithography’ to achieve nanodevices with enhanced performances. In this technology, the resolution of pattern integrations is significantly rely on the materials' properties of polydimethylsiloxane (PDMS) stamps. Since commercial PDMS stamps have shown limitations in nano-scale resolution soft lithography due to their low physical toughness and high thermal expansion coefficients, we developed stiffer, photocured PDMS silicon elastomers designed, specifically for nano-sized soft lithography and photopatternable nanofabrications.

Thermal expansion coefficients of NH4ReO4and NH4IO4down to 58 K

1985 ◽  
Vol 82 (3) ◽  
pp. 1611-1612 ◽  
Author(s):  
Stanley L. Segel ◽  
H. Karlsson ◽  
T. Gustavson ◽  
K. Edstrom
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

scholarly journals Organizing Cells Within Non-Periodic Microarchitectured Materials That Achieve Graded Thermal Expansions

2015 ◽  
Author(s):  
Jonathan B. Hopkins ◽  
Lucas A. Shaw ◽  
Todd H. Weisgraber ◽  
George R. Farquar ◽  
Christopher D. Harvey ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Thermal Expansion ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Element Analysis ◽  
Thermal Expansion Coefficients ◽  
Large Lattice ◽  
Unit Cells ◽  
Expansion Coefficients ◽  
Bulk Behavior

The aim of this paper is to introduce an approach for optimally organizing a variety of different unit cell designs within a large lattice such that the bulk behavior of the lattice exhibits a desired Young’s modulus with a graded change in thermal expansion over its geometry. This lattice, called a graded microarchitectured material, can be sandwiched between two other materials with different thermal expansion coefficients to accommodate their different expansions or contractions caused by changing temperature while achieving a desired uniform stiffness. First, this paper provides the theory necessary to calculate the thermal expansion and Young’s modulus of large multi-material lattices that consist of periodic (i.e., repeating) unit cells of the same design. Then it introduces the theory for calculating the graded thermal expansions of a large multimaterial lattice that consists of non-periodic unit cells of different designs. An approach is then provided for optimally designing and organizing different unit cells within a lattice such that both of its ends achieve the same thermal expansion as the two materials between which the lattice is sandwiched. A MATLAB tool is used to generate images of the undeformed and deformed lattices to verify their behavior and various examples are provided as case studies. The theory provided is also verified and validated using finite element analysis and experimentation.

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