Control of Volume Fraction of Non-180° Domains by Thermal Strain in Epitaxial Rhombohedral Pb(Zr, Ti)O3 Thick Films

2013 ◽  
Vol 1507 ◽  
Author(s):  
Yoshitaka Ehara ◽  
Satoru Utsugi ◽  
Takahiro Oikawa ◽  
Tomoaki Yamada ◽  
Hiroshi Funakubo
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Growth Temperature ◽  
Volume Fraction ◽  
Thick Films ◽  
Thermal Strain ◽  
Cooling Process ◽  
Volume Fractions ◽  
Oriented Films

ABSTRACTEpitaxial rhombohedral Pb(Zr0.65Ti0.35)O3films with (100) and (110)/(10-1) and (111)/(11-1) orientations were grown on various kinds of singlecrystal substrates having different thermal expansion coefficient. Volume fractions of (110) and (111) orientations in respective (110)/(10-1) and (111)/(11-1)-oriented films were almost linearly increased with increasing thermal strain, εthermal, applied to the films that wasgenerated under the cooling process after the deposition from the growth temperature to the Curie temperature.Observed saturationpolarization (Psat)was changed linearly with the volume fractions of (110) and (111) orientations, in the same manner asthe volume fractions of (001) and (101) orientations in (001)/(100) and (101)/(110) oriented tetragonal Pb(Zr,Ti)O3 filmsreported previously. These results showed that the volume fraction of the non-180o domains Pb(Zr,Ti)O3films of both tetragonal and rhombohedral symmetriescan be manipulated by εthermal, which brings possibly to control the Psat value.

scholarly journals A New Equation for the Determination of the Thermal Expansion Coefficient of Particulate Composites

1996 ◽  
Vol 5 (1) ◽  
pp. 096369359600500
Author(s):  
A. R. Boccaccini
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Volume Fraction ◽  
Particulate Composites ◽  
Volume Fractions ◽  
Original Analysis ◽  
Experimental Values ◽  
New Equation

A new equation has been derived for the determination of the thermal expansion coefficient of isotropic particulate composites. An original analysis by Tummala and Friedberg was modified by incorporating the dependence of the internal thermal stress on the inclusion volume fraction, as known from the literature. For low volume fractions of inclusions the new equation gives similar values to the original Tummala and Friedberg equation. For intermediate volume fractions, however (≈0.3 ≤ f ≤ ≈0.7), the present equation is shown to be in better agreement with experimental values for different composite systems investigated.

Bimaterial Micro-Structured Annulus With Zero Thermal Expansion Coefficient

2017 ◽  
Author(s):  
Yan Xie ◽  
Dengfeng Lu ◽  
Jingjun Yu
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
High Speed ◽  
Thermal Strain ◽  
Geometric Constraints ◽  
Geometrical Parameters ◽  
Thermal Behaviors ◽  
Lattice Cell ◽  
Triangular Cell

This paper mainly concentrates on the design and analysis of the annulus with zero thermal expansion coefficient (ZTE) aiming to solve the heat generation and deformation in high speed bearing. First, a fork-like lattice cell inspired by the basic triangular cell is put forward and further applied to construct an annulus. The stretch-dominated lattice cell utilizes the Poisson’s contraction effect to achieve the tailorable thermal expansion coefficient (CTE). The thermal behaviors differences between the continuous interfaces and lattice cells will lead to the internal stress. Thus, the CTE of the annulus consisting of the lattice cell can be tailored to zero even negative values through the offset between the thermal-strain and force-strain. Then a theoretical model is established with some appropriate assumptions to reveal the quantitative relations among the geometrical parameters, material properties and equivalent CTEs thoroughly. The prerequisites for realizing a zero CTE are further derived in terms of material limitations and geometric constraints. Finally, FEA method is implemented to verify and analyze the thermal behaviors of annulus. The proposed annulus design characterized by the CTE tunability, structure efficiency and continuous interfaces is hopefully to be applied in the high speed bearings, adapters between the shaft and collar and fastener screws.

Thermal Expansion Coefficient of Ni Base Alloy Composite Coating Containing Spheroidal Ceramic Grains

2010 ◽  
Vol 44-47 ◽  
pp. 2148-2151
Author(s):  
Xie Quan Liu ◽  
Xin Hua Ni ◽  
Shu Qin Zhang ◽  
Wan Heng He
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Composite Coating ◽  
Expansion Coefficient ◽  
Base Alloy ◽  
Thermal Strain ◽  
Phase Cell ◽  
Alloy Composite ◽  
Random Orientation ◽  
Two Phase

Ni base alloy composite coating containing spheroidal ceramic grains can be fabricated by a vacuum fusion sintering method. Composite coating was mainly composed of Ni base alloy and spheroidal ceramic grains with random orientation. The three-phase model is used to determine the thermal expansion coefficient of the composite coating. First, Eshebly-Mori-Tanaka method was used to determine thermal disturbance strain in two-phase cell aroused thermal inconsistency. Then, average thermal strain in the two-phase cell aroused by thermal inconsistency is gained by the means of volume equilibration. The two-phase cell is transverse isotropy and has two independent thermal expansion coefficients. Finely, based on mean strain of Ni base alloy ceramic composite coating containing spheroidal ceramic grains, the effective thermal expansion coefficient of the composite coating is obtained by considering random orientation of two-phase cells. Ni base alloy composite coating containing spheroidal ceramic grains is isotropy and has one independent thermal expansion coefficient.

Computational Design and Development of Alumina-Nickel Droplet Composites

2016 ◽  
Author(s):  
S. Sohail Akhtar ◽  
A. F. M. Arif ◽  
M. U. Siddiqui ◽  
Kabeer Raza ◽  
L. Taiwo Kareem ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Volume Fraction ◽  
Matrix Material ◽  
Microstructural Analysis ◽  
Computational Design ◽  
Minimum Size

Computational design for property management of composite materials offers a cost sensitive alternate approach in order to understand the mechanisms involved in the thermal and structural behavior of material under various combinations of inclusions and matrix material. The present study is concerned with analyzing the elasto-plastic and thermal behavior of Al2O3-Ni droplet composites using a mean field homogenization and effective medium approximation (EMA) using an in-house code. Our material design approach relies on a method for predicting potential optimum thermal and structural properties for Al2O3-Ni composites by considering the effect of inclusion orientation, volume, size, thermal interface resistance, percolation and porosity. The primary goal for designing such alumina-based composites is to have enhanced thermal conductivity for effective heat dissipation and spreading capabilities. At the same time, other functional properties like thermal expansion coefficient, elastic modulus, and electrical resistivity have to be maintained or enhanced. The optimum volume fraction was found to occur between 15 and 20 vol. %Ni while the average nickel particle size of 5 μm was found a minimum size that will enhance the thermal conductivity. The Young’s modulus was found decreasing as the volume fraction of nickel increases, which would result in enhanced fracture toughness. Electrical conductivity was found to be greatly affected by the percolation phenomenon in the designed range of volume fraction minimum particle size. As a validation, Al2O3 composites with 10% and 15% volume fraction Ni and droplet size of 18 μm are developed using spark Plasma Sintering process. Thermal conductivity and thermal expansion coefficient of the samples are measured to complement the computational design. Microstructural analysis of the sintered samples was also studied using optical microscope to study the morphology of the developed samples. It was found that the present computational design tool was accurate enough in predicting the desired properties of Al2O3-Ni composites.

Microstructure Modeling for Prediction of Thermal Expansion Coefficient of Plain Weave C/SiC Considering Manufacturing Porosities

2011 ◽  
Vol 399-401 ◽  
pp. 315-319 ◽  
Author(s):  
Sheng Li Lv ◽  
Qing Na Zeng ◽  
Lei Jiang Yao ◽  
Xiao Yan Tong
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Volume Fraction ◽  
Coefficient Of Thermal Expansion ◽  
Fibre Bundles ◽  
Plain Weave ◽  
Microstructure Modeling ◽  
Crack Volume ◽  
The Matrix

The aim of this paper is to propose a microstructure modeling for prediction of thermal conductivity of plain weave C/SiC fibre bundles considering manufacturing flaws. Utilizing photomicrographs taken by scanning electron microscope (SEM), we established an accurate sub representative volume element (sub-RVE) model for carbon fiber bundles and RVE for the plain weave C/SiC composite with consideration of four classes of manufacturing porosity. The thermal expansion coefficient of carbon fibre bundles on axial and transverse coefficient of thermal expansion is calculated, respectively. Based on which thermal expansion coefficient of plain weave C/SiC is obtained with the value of 2.71×10-6 in-plain, which has a good correlation with experimental value. The influences of different manufacturing flaws on material’s thermal expansion coefficient are studied. The study shows that as the matrix porosity or crack volume fraction is increasing, thermal expansion coefficient of plain weave C/SiC is decreasing correspondingly while the speed gradually slows.

Thermoelastic Properties of a Novel Fuzzy Fiber-Reinforced Composite

2013 ◽  
Vol 80 (6) ◽  
Author(s):  
S. I. Kundalwal ◽  
M. C. Ray
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Volume Fraction ◽  
Effect Of Temperature ◽  
Fiber Reinforced ◽  
Thermoelastic Properties ◽  
Fiber Reinforced Composite ◽  
Reinforced Composite ◽  
Generalized Method Of Cells

The effective thermoelastic properties of a fuzzy fiber-reinforced composite (FFRC) have been estimated by employing the generalized method of cells approach and the Mori–Tanaka method. The novel constructional feature of this fuzzy fiber-reinforced composite is that the uniformly aligned carbon nanotubes (CNTs) are radially grown on the circumferential surface of the horizontal carbon fibers. Effective thermoelastic properties of the fuzzy fiber-reinforced composite estimated by the generalized method of cells approach have been compared with those predicted by the Mori–Tanaka method. The present work concludes that the axial thermal expansion coefficient of the fuzzy fiber-reinforced composite slightly increases for the lower values of the carbon fiber volume fraction, whereas the transverse thermal expansion coefficient of the fuzzy fiber-reinforced composite significantly decreases over those of the composite without CNTs. Also, the results demonstrate that the effect of temperature variation on the effective thermal expansion coefficients of the fuzzy fiber-reinforced composite is negligible.

scholarly journals THE INFLUENCE OF MORTAR MICROSTRUCTURE ON ITS THERMAL EXPANSION COEFFICIENT

2003 ◽  
Vol 9 (1) ◽  
pp. 45-51
Author(s):  
Darius Zabulionis ◽  
Gediminas Marčiukaitis
Keyword(s):  
Thermal Expansion ◽  
Bulk Modulus ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Composite Structure ◽  
Parametric Study ◽  
Coefficient Of Thermal Expansion ◽  
Thermal Strain ◽  
Interfacial Transition Zone ◽  
Aggregate Fractions

Thermal strain is one of the factors causing additional stresses in a composite structure. It is necessary to calculate the coefficient of thermal expansion in evaluating thermal strains. According to the research, concrete is a material consisting of three phases: aggregate, interfacial transition zone (ITZ) and cement paste. The article presents the technique which enables the estimation of the thermal expansion coefficient of the mortar consisting of various aggregate fractions and covered with ITZ layer. A parametric study of various ITZ layer characteristics influencing the coefficient of thermal expansion has been carried out in the present paper. It has been determined that dry mortar or concrete could be treated as a material consisting of two components. While evaluating moist mortar or concrete it is necessary to take into account the depth of the ITZ the bulk modulus and the coefficient of thermal expansion.

scholarly journals Mechanical and thermal-expansion characteristics of Ca10(PO4)6(OH)2-Ca3(PO4)2 composites

2006 ◽  
Vol 38 (3) ◽  
pp. 245-253 ◽  
Author(s):  
G. Ruseska ◽  
E. Fidancevska ◽  
J. Bossert
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Thermal Equilibrium ◽  
Volume Fraction ◽  
Applied Model ◽  
Proposed Model ◽  
The Subject ◽  
Model Equations ◽  
Synergism Effect

Three types of composites consisting of Ca10(PO4)6(OH)2 and Ca3(PO4)2 with composition: 75% (wt) Ca10(PO4)6(OH)2: 25%(wt) Ca3(PO4)2; 50%(wt) Ca10(PO4)6(OH)2: 50%(wt)Ca3(PO4)2 and 25 %(wt) Ca10(PO4)6(OH)2: 75%(wt) Ca3(PO4)2 were the subject of our investigation. Sintered compacts were in thermal equilibrium, which was proved by the absence of hysteresis effect of the dependence ?L/L=f(T) during heating /cooling in the temperature interval 20-1000-200C. Sintered compacts with the previously mentioned composition possess 26-50% higher values of the E-modulus, G-modulus and K-modulus indicating the presence of a synergism effect. Several proposed model equations for predicting the thermal expansion coefficient in dependence of the thermal and elastic properties of the constitutive phases and their volume fractions, given by: Turner, Kerner, Tummala and Friedberg, Thomas and Taya, were used for making correlations between mechanical and thermal-expansion characteristics of the Ca10(PO4)6(OH)2 - Ca3(PO4)2 composites. Application of the previously mentioned model equations to all kinds of composites leads to the conclusion that the experimentally obtained results for the thermal expansion coefficient are in an excellent agreement with the theoretical calculated values on account of the volume fraction of each constitutive phase and with all applied model equations, with a coefficient of correlation from 98.16-99.86 %.

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