Processing of Porous Zirconium Tungstate and Their Thermomechanical Properties

2014 ◽  
Author(s):  
Mingang Wang ◽  
Truong Do ◽  
Patrick Kwon
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Processing Technique ◽  
Thermomechanical Properties ◽  
Processing Route ◽  
Full Density ◽  
Ceramic Powders ◽  
Zirconium Tungstate ◽  
Spherical Graphite ◽  
New Processing

This paper explores a new processing method to fabricate porous zirconium tungstate (ZrW2O8 or ZT) with the porosity content up to 40% in volume. The method uses spherical graphite powders that are mechanically stable, allowing us to compact with ceramic powders in dry condition. Thus, the ceramic powders mixed with spherical graphite powders can be compacted and sintered to a near full density. During sintering, the graphite powders burn out without damaging the powder compact due to their inherent near-zero thermal expansion. The processing route discussed in this paper is applicable to all oxide ceramics where the sintering can take place in air and above 700°C to dissociate the graphite. In this paper, we have applied this processing technique to fabricate porous ZrW2O8. Many porous ZrW2O8 with a range of porosity levels were fabricated and tested for their theromomechanical properties including elastic modulus (E) and coefficient of thermal expansion (CTE). The experimentally determined properties were compared with the predictions based on the micromechanical Mori-Tanaka scheme.

scholarly journals Thermal Expansion Measurements in Fresh and Saline Ice Using Fiber Optic Strain Gauges and Multipoint Temperature Sensors Based on Bragg Gratings

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Aleksey Marchenko ◽  
Ben Lishman ◽  
David Wrangborg ◽  
Torsten Thiel
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Water Pressure ◽  
Thermomechanical Properties ◽  
Quality Data ◽  
Strain Gauges ◽  
Temperature Changes ◽  
Fbg Sensors ◽  
Ice Water ◽  
Good Quality Data

This paper describes the use of Fiber Bragg Grating (FBG) sensors to investigate the thermomechanical properties of saline ice. FBG sensors allowed laboratory measurements of thermal expansion of ice samples with a range of different sizes and geometries. The high sampling frequency, accuracy, and resolution of the FBG sensors provide good quality data across a temperature range from 0°C to −20°C. Negative values of the effective coefficient of thermal expansion were observed in ice samples with salinities 6 ppt, 8 ppt, and 9.4 ppt. A model is formulated under which structural transformations in the ice, caused by temperature changes, can lead to brine transfer from closed pockets to permeable channels, and vice versa. This model is compared to experimental data. Further, in experiments with confined floating ice, heating as well as thermal expansion due to vertical migration of liquid brine, caused by under-ice water pressure, was observed.

Rheological and Thermomechanical Properties of Meso and Non-Porous Silica Filled Epoxy Composites

2015 ◽  
Vol 815 ◽  
pp. 67-71
Author(s):  
Gang Li ◽  
Peng Li Zhu ◽  
Tao Zhao ◽  
Rong Sun ◽  
Daniel Lu
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Mesoporous Silica ◽  
Coefficient Of Thermal Expansion ◽  
Porous Silica ◽  
Thermomechanical Properties ◽  
Epoxy Composites ◽  
Silica Microspheres ◽  
Silica Filler

In the present study, epoxy based composite filled with meso and non-porous silica microspheres with similar size were prepared respectively and their rheological and thermo-mechanical properties were studied systematically. The results showed that the mesoporous silica/epoxy composites showed much higher viscosity, storage modulus and glass transition temperature (Tg) while lower coefficient of thermal expansion (CTE) than did epoxy composites with nonporous silica particles, which could be attributed to the stronger interface interaction between the mesoporous silica filler with larger specific surface area (BET) and the epoxy matrix.

High Temperature Stability of Zirconium Tungstate

2020 ◽  
Vol 993 ◽  
pp. 771-775
Author(s):  
Ping Zhai ◽  
Xiao Feng Duan ◽  
Da Qian Chen
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Solid Phase ◽  
Coefficient Of Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Tungstic Acid ◽  
High Temperature Stability ◽  
Zirconium Tungstate

In this paper, zirconium tungstate ceramic with negative thermal expansion coefficients was prepared from zirconium oxide and tungstic acid by solid phase synthesis and high temperature quenching technique with a sintering temperature of 1200 °C. The phase structure of the material was determined by X ray and the thermal expansion coefficient was measured by dilatometer, while the TG-DTA analysis of the prepared material was also carried out. The results showed that zirconium tungstate with high purity could be obtained by rapid chilled while fired at 1200 °C. The coefficient of thermal expansion at 300 °C was minus 8.5413 × 10-6K-1, which is identical with the theoretical value. The thermal expansion coefficient of the material was negative fired lower than 750 °C, while it was positive fired higher than 750 °C, and this indicates that the decomposition temperature of zirconium tungstate is about 750 °C.

Zirconium tungstate reinforced cyanate ester composites with enhanced dimensional stability

2009 ◽  
Vol 24 (7) ◽  
pp. 2235-2242 ◽  
Author(s):  
Prashanth Badrinarayanan ◽  
Ben Mac Murray ◽  
Michael R. Kessler
Keyword(s):  
Thermal Expansion ◽  
Dimensional Stability ◽  
Coefficient Of Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Thermomechanical Analysis ◽  
Dynamic Mechanical Properties ◽  
Filler Loading ◽  
Cyanate Ester ◽  
Scanning Calorimetry ◽  
Zirconium Tungstate

Zirconium tungstate (ZrW2O8) is a unique ceramic material characterized by isotropic negative thermal expansion behavior over a wide temperature range. Incorporation of ZrW2O8 is expected to improve the dimensional stability of polymers by reducing the overall coefficient of thermal expansion (CTE). In this work, the thermal and dynamic mechanical properties of a bisphenol E cyanate ester reinforced with various loadings of ZrW2O8 are examined. Thermomechanical analysis indicates that the incorporation of ZrW2O8 results in a decrease in CTE at temperatures above and below the glass transition temperature (Tg) of the neat resin. The dynamic storage moduli of the composites reinforced with ZrW2O8 are found to increase with increasing filler loading. Furthermore, the various phase behaviors exhibited by ZrW2O8 are also examined by differential scanning calorimetry measurements.

Thermomechanical Properties of Nickel Silicide: Dependence on the Microstructure

2005 ◽  
Vol 495-497 ◽  
pp. 1431-1436
Author(s):  
C. Torregiani ◽  
Jan D'Haen ◽  
K. Opsomer ◽  
M.J. Van Dal ◽  
Paul van Houtte ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Single Crystal Silicon ◽  
Orientation Distribution ◽  
Thermomechanical Properties ◽  
Nickel Silicide ◽  
Weighted Averaging ◽  
Crystal Silicon ◽  
Thermomechanical Behaviour

Nickel monosilicide (NiSi) is a key material in microelectronics and its thermomechanical properties play an important role in determining the stress/strain field generated in a transistor structure. The Coefficient of Thermal Expansion (CTE) is of particular importance in the determination of such a field. As NiSi is used in microelectronics in its polycrystalline form, it becomes of particular interest to study the thermomechanical behaviour of the NiSi aggregate, considered as a unique macroscopic body. The grain orientation of a 120 nm polycrystalline NiSi film grown on single crystal silicon has been studied by means of electron diffraction, and the evaluation of the CTE tensor of the film in the wafer reference frame has been performed by weighted averaging the single grain contributions. The results clearly show the importance of orientation distribution in determining the value of the equivalent coefficient of thermal expansion of the aggregate.

scholarly journals Intrinsic Thermal Shock Behavior of Common Rutile Oxides

Physics ◽  
2019 ◽  
Vol 1 (2) ◽  
pp. 290-300 ◽  
Author(s):  
Denis Music ◽  
Bastian Stelzer
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Elastic Modulus ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Density Functional ◽  
Coefficient Of Thermal Expansion ◽  
Thermomechanical Properties ◽  
Linear Coefficient ◽  
Shock Resistance

Rutile TiO2, VO2, CrO2, MnO2, NbO2, RuO2, RhO2, TaO2, OsO2, IrO2, SnO2, PbO2, SiO2, and GeO2 (space group P42/mnm) were explored for thermal shock resistance applications using density functional theory in conjunction with acoustic phonon models. Four relevant thermomechanical properties were calculated, namely thermal conductivity, Poisson’s ratio, the linear coefficient of thermal expansion, and elastic modulus. The thermal conductivity exhibited a parabolic relationship with the linear coefficient of thermal expansion and the extremes were delineated by SiO2 (the smallest linear coefficient of thermal expansion and the largest thermal conductivity) and PbO2 (vice versa). It is suggested that stronger bonding in SiO2 than PbO2 is responsible for such behavior. This also gave rise to the largest elastic modulus of SiO2 in this group of rutile oxides. Finally, the intrinsic thermal shock resistance was the largest for SiO2, exceeding some of the competitive phases such as Al2O3 and nanolaminated Ti3SiC2.

scholarly journals Thermomechanical Analysis of Ceramic Composites Using Object Oriented Finite Element Analysis

2021 ◽  
Author(s):  
Satyanarayan Patel
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Object Oriented ◽  
Thermomechanical Analysis ◽  
Ceramic Composites ◽  
Thermomechanical Properties ◽  
Element Analysis ◽  
Simulation Techniques ◽  
Barrier Coating

This chapter discussed the object oriented finite element (OOF2)-based studies for ceramic composites. OOF2 is an effective method that uses an actual microstructure image of the material/composites for simulation. The effect of filler inclusions on the thermomechanical properties (coefficient of thermal expansion, thermal conductivity, Young’s modulus, stress and strain) is discussed. For this purpose, various ceramics composites (thermal barrier coating and ferroelectric based) are considered at homogeneous and heterogeneous temperature/stress conditions. The maximum stress is found at the interface of the filler/matrix due to their mismatch of thermal expansion coefficient. Further, residual and localized interface stress distributions are evaluated to analyze the composite’s failure behavior. The possible integration of OOF2 with other simulation techniques is also explored.

Achieving theoretical thermal conductivity and coeffieicent of thermal expansion in a W-Cu composite sheet

2019 ◽  
Author(s):  
Xingang Wang ◽  
Peng Cao
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Thin Sheet ◽  
Rolling Direction ◽  
Thickness Reduction ◽  
Full Density ◽  
Infiltration Process ◽  
Good Surface ◽  
Composite Samples

W-20wt.%Cu composite sheets with full density and good surface quality were successfully fabricated through an infiltration process followed by a hot rolling. After a total thickness reduction of 75%, the majority of the tungsten (W) particles have been deformed and elongated along the rolling direction. The aspect ratio of the W particles in the composite has reached 2.5. The relative density increases considerably to a maximum value of 99.8% when the rolling ratio increases. The thermal conductivity and microhardness of the W-Cu composites increase significantly with the rolling reduction. On the contrary, the coefficient of thermal expansion (CTE) of the composite samples decreases with the rolling ratio. Specifically, after subjected to 75% of thickness reduction, we obtained a large W-Cu thin sheet. This thin sheet demonstrates a low CTE of 7.27×10^-6/K and the highest thermal conductivity of 224.91 W/(m-K); both values are close to the respective theoretical ones.

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