Thermal Expansion Behavior of the Multiphase Composite System

2004 ◽  
Vol 449-452 ◽  
pp. 765-768
Author(s):  
Chong Sung Park ◽  
Hyun Seok Hong ◽  
Myung Ho Kim ◽  
Chong Mu Lee
Keyword(s):  
Thermal Expansion ◽  
Composite System ◽  
Welding Process ◽  
High Volume ◽  
Volume Percent ◽  
New Approach ◽  
Composite Systems ◽  
Expansion Behavior ◽  
The Matrix ◽  
Multiphase Composite

A new approach for the CTE on the basis of Ashelby.s cutting and welding process was made for the analysis of the thermal expansion behaviors of Al-Si alloys and composites. In this theoretical approach, it was considered that relaxation of residual stress could create an elastoplastic zone in the matrix around a particle during cooling. A comparison of the measured CTEs with the calculated ones for the Al-Si-SiCp and Al-Si-Al2O3 composite systems was performed in terms of the volume percent and the size of reinforced phases. The calculated results revealed that the linear CTE of the both composite depends on the size of the reinforce phases, especially at the composite systems with a low volume percent of the reinforce phases. The increase in the volume percentages of Al2O3, SiCp and Si phase lowers the linear CTEs of the systems. The measured CTEs was deviated less than about ten percents from the calculated ones at composites with a high volume percent. The deviations of the CTEs of reinforced phases are about 4 - 6 vol% from real composite systems.

Thermal Expansion of Composite System Epoxy Resin/Recycled Carbon Fibers

2020 ◽  
Vol 994 ◽  
pp. 162-169
Author(s):  
Štěpánka Dvořáčková ◽  
Dora Kroisová
Keyword(s):  
Experimental Study ◽  
Thermal Expansion ◽  
Epoxy Resin ◽  
Carbon Fibers ◽  
Composite System ◽  
Linear Thermal Expansion Coefficient ◽  
Linear Thermal Expansion ◽  
Carbon Fibres ◽  
Sample Matrix ◽  
Composite Systems

This experimental study deals with the problematics of thermal expansion α [10-6/K] of the composite systems based on recycled carbon fibres reinforced epoxy resin. The epoxy resin CHS – EPOXY 520 (EPOXY 15), cured with the hardener P11 (Districhem, s.r.o.), was chosen as a sample matrix. Recycled carbon fibres with a diameter of 7 μm and a length of 100 μm (Easy Composites Ltd.) were the filler. In the experiment, samples with the fulfilment of 10, 20, 40, 60, 80, 90 and 100 phr were prepared. The samples were being poured into silicone molds, cured at an overpressure of 0.7 MPa and a temperature of 23 ± 2 °C for 24 hours. A thermomechanical analyzer was used to determine the thermal expansion of composite systems. The addition of recycled carbon fibers to epoxy resin can reduce the coefficient of linear thermal expansion at 20°C in half, from the original α = 45 to 55 × 10-6/K for non-filled epoxy resin to α = 25 to 27 × 10-6/K for filled epoxy resin. Optimal filling is at the level of 40 phr, with higher filling there is no further reduction of the linear thermal expansion coefficient.

scholarly journals Abrasion of Polymeric Composites on Basis of Machining Splinters from Hardfacing Alloys – Usable in Agrocomplex

2014 ◽  
Vol 62 (1) ◽  
pp. 261-266 ◽  
Author(s):  
Petr Valášek ◽  
Miroslav Müller
Keyword(s):  
Composite System ◽  
Field Tests ◽  
Functional Surface ◽  
Inorganic Particles ◽  
Composite Systems ◽  
The Matrix ◽  
Polymeric Particle ◽  
Three Body Abrasion ◽  
Three Body ◽  
Agricultural Machines

A paper focuses on a description of two-body and three-body abrasion wear of polymeric particle composites with fillers on a basis of machining splinters from hardfacing alloys. The abrasive wear is typical for functional surfaces of agricultural machines processing the soil. One of possibilities of the functional surface renovation is an application of resistant layers in a form of composite systems. Just the inclusion of hard inorganic particles into a polymeric matrix significantly increases its wear resistance. So long as the primary filler is replaced by the waste – by particles from the material machining – the matrix in which the filler is dispersed is a bearer of a material recyclation. This way of the recyclation is inexpensive, economic and sensitive to environment. The paper focuses on the experimental description of the two-body and three-body abrasion and the composites hardness, it describes a production of a prototype for field tests with the functional surface on the basis of the investigated composite system at the same time.

The Chemical Plating Copper of the SiC Particles and Thermal Expansion Behavior of the SiCp/Cu Composites

2013 ◽  
Vol 544 ◽  
pp. 334-338
Author(s):  
Ming Hu ◽  
Yun Long Zhang ◽  
You Jin Liu ◽  
Jing Gao
Keyword(s):  
Thermal Expansion ◽  
Pure Copper ◽  
Copper Matrix ◽  
Copper Plating ◽  
Chemical Plating ◽  
Thermal Expansion Coefficients ◽  
Sic Particles ◽  
Expansion Behavior ◽  
The Matrix

In this paper, the chemical copper plating technology was utilized to modify the SiC particles and the SiCp/Cu composites were fabricated by the pressure-less sintering technology. The effect of pretreatment solution on the coating quality of the SiC particles was discussed in details. The pure copper and copper- coated SiC particles or SiC particles without coated copper were used to fabricate the SiCp/Cu composites. At the same time, the microstructures and thermal expansion coefficients of the SiCp/Cu composites were studied. The results showed that the uniform and continuous Cu coating on the SiC particles can be obtained after chemical copper plating, and the copper-coated SiC particles can distributed continuously in the matrix of the SiCp/Cu composites. The chemical copper plating technology could improve the wettability between SiC particles and copper matrix obviously. The addition of the SiC particle could reduce the CTE of the SiCp/Cu composites.

The electronic states of composite systems

1956 ◽  
Vol 235 (1203) ◽  
pp. 537-543 ◽  
Keyword(s):  
Density Operator ◽  
Spectroscopic Data ◽  
Composite System ◽  
Three Dimensional ◽  
Transition Density ◽  
Matrix Elements ◽  
Multipole Moments ◽  
Composite Systems ◽  
The Matrix ◽  
The Individual

In order to relate the electronic eigenstates of a composite system to those of its constituent parts one requires the matrix elements of the interaction Hamiltonian between the unperturbed states of the system . It is shown that in the absence of electron exchange these matrix elements, which are usually approximated as multipole series, may be accurately expressed as electrostatic repulsion energies between three-dimensional electric distributions localized on the subsystems. These distributions are them selves the matrix elements of the electric density operator between the eigenstates of the individual subsystems, and their multipole moments are identified as the permanent moments of the subsystems in their various states and the transition moments between these states. The name ‘transition density' is proposed for the off-diagonal elements of the electric density operator, and an examination of its properties suggests that the transition density may be a useful concept for summarizing and systematizing spectroscopic data on atomic and molecular assemblies.

Effect of Formulation on Thermal Expansion Behavior of Bamboo/HDPE/PA6 Composites Using TMA

2013 ◽  
Vol 773 ◽  
pp. 502-507
Author(s):  
Run Zhou Huang ◽  
Xin Wu Xu ◽  
Cheng Jun Zhou ◽  
Yang Zhang ◽  
Qing Lin Wu
Keyword(s):  
Thermal Expansion ◽  
Coupling Agent ◽  
Thermal Expansion Behavior ◽  
Loading Level ◽  
Expansion Behavior ◽  
The Matrix

Bamboo/HDPE/PA6 composites have been discussed by systematically studying the effect of formulation on thermal expansion properties. PA6 filled HDPE seemed not significantly influence LTEC of HDPE/PA composites system when the PA loading level increased form 0 % to 20%. It was investigated that BF significantly reduced LTEC value compared with LTEC of HDPE/PA. The reduction of the LTEC appear in HDPE/bamboo composites was dependent on the matrix and filler. Coupling agent can make the LTEC of HDPE/bamboo composites reduced, but the reduction was larger than that of only filler.

scholarly journals Fabrication and Characterization of the Modified EV31-Based Metal Matrix Nanocomposites

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 125
Author(s):  
Seyed Kiomars Moheimani ◽  
Mehran Dadkhah ◽  
Mohammad Hossein Mosallanejad ◽  
Abdollah Saboori
Keyword(s):  
Thermal Expansion ◽  
Mechanical Strength ◽  
Metal Matrix ◽  
Coefficient Of Thermal Expansion ◽  
Structural Effect ◽  
Metal Matrix Nanocomposites ◽  
Mechanical Stirring ◽  
Specific Strength ◽  
The Matrix ◽  
Matrix Nanocomposites

Metal matrix nanocomposites (MMNCs) with high specific strength have been of interest for numerous researchers. In the current study, Mg matrix nanocomposites reinforced with AlN nanoparticles were produced using the mechanical stirring-assisted casting method. Microstructure, hardness, physical, thermal and electrical properties of the produced composites were characterized in this work. According to the microstructural evaluations, the ceramic nanoparticles were uniformly dispersed within the matrix by applying a mechanical stirring. At higher AlN contents, however, some agglomerates were observed as a consequence of a particle-pushing mechanism during the solidification. Microhardness results showed a slight improvement in the mechanical strength of the nanocomposites following the addition of AlN nanoparticles. Interestingly, nanocomposite samples were featured with higher electrical and thermal conductivities, which can be attributed to the structural effect of nanoparticles within the matrix. Moreover, thermal expansion analysis of the nanocomposites indicated that the presence of nanoparticles lowered the Coefficient of Thermal Expansion (CTE) in the case of nanocomposites. All in all, this combination of properties, including high mechanical strength, thermal and electrical conductivity, together with low CTE, make these new nanocomposites very promising materials for electro packaging applications.

scholarly journals On the Modular Operator of Mutli-component Regions in Chiral CFT

2021 ◽  
Author(s):  
Stefan Hollands
Keyword(s):  
Field Theory ◽  
Integral Equation ◽  
Hilbert Problem ◽  
Matrix Elements ◽  
New Approach ◽  
Conformal Field ◽  
The Matrix ◽  
Kms Condition ◽  
Modular Operator ◽  
Riemann Hilbert Problem

AbstractWe introduce a new approach to find the Tomita–Takesaki modular flow for multi-component regions in general chiral conformal field theory. Our method is based on locality and analyticity of primary fields as well as the so-called Kubo–Martin–Schwinger (KMS) condition. These features can be used to transform the problem to a Riemann–Hilbert problem on a covering of the complex plane cut along the regions, which is equivalent to an integral equation for the matrix elements of the modular Hamiltonian. Examples are considered.

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