HDPE Matrix Composites Filled With Ca4La6(SiO4)4(PO4)2O2 for Microwave Substrate Applications

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Dhanesh Thomas ◽  
Mailadil T. Sebastian
Keyword(s):  
Dielectric Loss ◽  
Relative Permittivity ◽  
Volume Fraction ◽  
Linear Thermal Expansion ◽  
Theoretical Models ◽  
Ceramic Composites ◽  
Filler Loading ◽  
Scanning Electron Micrographs ◽  
Melt Mixing ◽  
5 Ghz

Polymer–ceramic composites have been prepared by dispersing Ca4La6(SiO4)4(PO4)2O2 (CLSP) ceramic filler in high density polyethylene (HDPE) matrix through melt mixing. Scanning electron micrographs reveal the extent of filler dispersion. The dielectric properties at 1 MHz and 5 GHz have been investigated as a function of filler content. The relative permittivity increases with filler loading, maintaining a low dielectric loss. The composite with highest filler loading of 0.4 volume fraction shows a relative permittivity of 5.1 and dielectric loss of 2.3 × 10−3 at 5 GHz. Experimentally observed values of relative permittivity at 5 GHz have been compared with the values calculated using various theoretical models. Both the coefficient of linear thermal expansion and tensile strength have been observed to decrease with filler loading, reaching a minimum value of 117 ppm/ °C and 20.7 MPa, respectively, at 0.4 volume fraction of filler. The composite with maximum filler loading of 0.4 volume fraction shows the highest thermal conductivity (TC) and is 1.2 W m−1 K−1.

Microwave Dielectric Characteristics of Butyl Rubber- Barium Titanate Composites

2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000428-000435
Author(s):  
J. Chameswary ◽  
M. T. Sebastian
Keyword(s):  
Barium Titanate ◽  
Relative Permittivity ◽  
Volume Fraction ◽  
Filler Content ◽  
Microwave Dielectric Properties ◽  
Theoretical Models ◽  
Butyl Rubber ◽  
Microwave Dielectric ◽  
Tan Δ ◽  
5 Ghz

Butyl rubber-micron barium titanate (BR/BT) and butyl rubber-nano barium titanate (BR/nBT) composites were prepared by sigma mixing followed by hot pressing. The tensile tests show that both the composites were mechanically flexible. The microwave dielectric properties of both BR/BT and BR/nBT composites were investigated as a function of ceramic loading and were found to be improved with filler content. The butyl rubber has relative permittivity (εr) of 2.4 and loss tangent (tan δ) of 0.0017 at 5 GHz. At a filler loading of 0.24 volume fraction (vf) of micron sized barium titanate (BaTiO3) powder loading, the composite attained a εr of 7 and tan δ of 0.014 and for the same filler content of nano BaTiO3 the composite have εr of 8.9 and tan δ of 0.019 at 5 GHz. The thermal stability of the relative permittivity of both the composites was investigated. The experimental values of εr of both BR/BT and BR/nBT composites were compared with theoretical models.

Ceramic-Polymer Composites with Low Dielectric Loss for Microwave Antennas and Wireless Sensors

2015 ◽  
Vol 655 ◽  
pp. 153-158 ◽  
Author(s):  
Li Zhang ◽  
Zhen Xing Yue ◽  
Long Tu Li
Keyword(s):  
Dielectric Loss ◽  
Polymer Composites ◽  
Relative Permittivity ◽  
Volume Fraction ◽  
Ceramic Powder ◽  
Microwave Frequency ◽  
Theoretical Models ◽  
Processing Technique ◽  
Low Dielectric ◽  
Extrusion Processing

The low dielectric loss ceramic-polymer composites were prepared by extrusion processing technique with high density polyethylene (HDPE) as matrix and high permittivity ceramic powder in BaO-Nd2O3-TiO2(BNT) system as filter. The dielectric response in microwave frequency range was characterized, and the experimentally observed dielectric properties were compared with the theoretical models. The relative permittivity of the composites is increased from 3 to 10 with the increase in the volume fraction of BNT filter from 10 to 40 vol%. The dielectric losses of composites are less than 0.001 for all compositions. For 40 vol% ceramic loaded HDPE, the relative permittivity of 10 and loss tangent of 0.0007 at 7 GHz were obtained. The BNT-HDPE composites are promising materials for microwave dielectric antenna applications.

PREPARATION AND CHARACTERIZATION OF MECHANICALLY FLEXIBLE RUBBER-CERAMIC COMPOSITE DIELECTRICS

2013 ◽  
Vol 22 ◽  
pp. 148-152
Author(s):  
DHANESH THOMAS ◽  
M. T. SEBASTIAN
Keyword(s):  
Dielectric Loss ◽  
Hot Pressing ◽  
Relative Permittivity ◽  
Ceramic Composite ◽  
Temperature Stability ◽  
Theoretical Models ◽  
Butyl Rubber ◽  
Low Dielectric

Butyl rubber — Ca 4 La 6( SiO 4)4( PO 4)2 O 2 — composites have been prepared by sigma mixing and hot pressing. The relative permittivity of the composites varies from 3 to 5.3 at 1 MHz. All the composites show low dielectric loss of the order of 10−3 at 1 MHz. The experimentally observed values of relative permittivity are correlated with those calculated using various theoretical models. The composites show good temperature stability of relative permittivity.

Low Dielectric Loss Polymer-Ceramic Composites for Wireless Temperature Sensation

2014 ◽  
Vol 602-603 ◽  
pp. 752-756 ◽  
Author(s):  
Li Zhang ◽  
Zhen Xing Yue ◽  
Long Tu Li
Keyword(s):  
Dielectric Loss ◽  
Relative Permittivity ◽  
High Density Polyethylene ◽  
Microstrip Antenna ◽  
Ceramic Composites ◽  
Processing Technique ◽  
Uhf Rfid ◽  
Temperature Sensation ◽  
Low Dielectric ◽  
Extrusion Processing

The low dielectric loss polymer-ceramic composites with high density polyethylene (HDPE) as matrix and BaO-Nd2O3-TiO2(BNT) as filter for wireless temperature sensation were prepared by an extrusion processing technique. For 30vol % ceramic loaded HDPE, as the ambient temperature increases from 30 to 100 °C, the relative permittivity and loss tangent of the composite vary from 6.25 to 6.09 and from 0.004 to 0.011 respectively, and the temperature coefficient of relative permittivity is -370ppm/°C. By using this composite as the patch microstrip antenna substrate, a simple UHF RFID temperature sensor antenna is fabricated and measured. The experimental results show that a 2MHz/10°C frequency increment can be obtained at 900 MHz in the temperature range from 25 to 100°C.

scholarly journals Temperature dependence of hardness prediction for high-temperature structural ceramics and their composites

2021 ◽  
Vol 10 (1) ◽  
pp. 586-595
Author(s):  
Ruzhuan Wang ◽  
Dingyu Li ◽  
Weiguo Li
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Material Design ◽  
Theoretical Models ◽  
Ceramic Composites ◽  
Basic Material ◽  
Experimental Measurements ◽  
Control Mechanisms ◽  
Oxide Ceramics ◽  
Structural Ceramics

Abstract Hardness is one of the important mechanical properties of high-temperature structural ceramics and their composites. In spite of the extensive use of the materials in high-temperature applications, there are few theoretical models for analyzing their temperature-dependent hardness. To fill this gap in the available literature, this work is focused on developing novel theoretical models for the temperature dependence of the hardness of the ceramics and their composites. The proposed model is just expressed in terms of some basic material parameters including Young’s modulus, melting points, and critical damage size corresponding to plastic deformation, which has no fitting parameters, thereby being simple for materials scientists and engineers to use in the material design. The model predictions for the temperature dependence of hardness of some oxide ceramics, non-oxide ceramics, ceramic–ceramic composites, diamond–ceramic composites, and ceramic-based cermet are presented, and excellent agreements with the experimental measurements are shown. Compared with the experimental measurements, the developed model can effectively save the cost when applied in the material design, which could be used to predict at any targeted temperature. Furthermore, the models could be used to determine the underlying control mechanisms of the temperature dependence of the hardness of the materials.

Residual stresses in Al2O3/Y-TZP Ceramic Laminates Fabricated by Tape and Slip Casting

2008 ◽  
Vol 571-572 ◽  
pp. 327-332 ◽  
Author(s):  
Jesus Ruiz-Hervias ◽  
Giovanni Bruno ◽  
Jonas Gurauskis ◽  
A.J. Sanchez-Herencia ◽  
C. Baudin
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Volume Fraction ◽  
Tape Casting ◽  
Slip Casting ◽  
Ceramic Composites ◽  
Processing Route ◽  
Alumina Matrix ◽  
Stress Profiles

Residual stress profiles were measured by neutron diffraction in Al2O3/Y-TZP ceramic composites containing 5 and 40 vol.% Y-TZP fabricated by conventional slip casting and by a novel tape casting route. Residual stresses in the zirconia are tensile and increase as its volume fraction decreases. For the alumina matrix, residual stress is compressive and increases with the zirconia volume fraction. In the composite with 5 vol.% zirconia, the processing route does not have an influence on residual stresses. However, in the composite with 40 vol.% zirconia, residual stresses are different in the samples obtained by both processing routes.

Analysis of the Characteristics on Dielectric Barrier Discharges Depending on the Relative Permittivity and Frequency

2018 ◽  
Vol 875 ◽  
pp. 113-116 ◽  
Author(s):  
Don Kyu Lee
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Relative Permittivity ◽  
Discharge Voltage ◽  
Frequency Region ◽  
Dielectric Barrier Discharges ◽  
Dielectric Barrier ◽  
Dielectric Layers ◽  
Green Sheet ◽  
Barrier Discharges

Various studies are being conducted on the application of DBD (Dielectric barrier discharges). The internal dielectric has a very important characteristic on DBD, thus we analyze of the characteristics on dielectric barrier discharges depending on the relative permittivity and frequency. Through simulation, the discharge voltage was calculated based on relative permittivity and frequency of real used dielectrics (Green sheet, Down dielectric, white dielectric). We investigate that increased relative permittivity and fast frequency occur the decrease of the firing voltage. Also, we investigate the frequency dependence of the dielectric constant and dielectric loss of dielectric layers measured at a frequency region of 100Hz to 10MHz. In a condition of drive within 1MHz, with regard to the change of real and imaginary part according to frequency, it has quite stable dielectric constant in the condition of drive within 1MHz.

Microstructure and Mechanical Properties of In Situ TiB2/6061 Composites

2012 ◽  
Vol 535-537 ◽  
pp. 14-17
Author(s):  
Long Hua Zhong ◽  
Yu Tao Zhao ◽  
Song Li Zhang ◽  
Rong Wen
Keyword(s):  
Master Alloy ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Melt Mixing ◽  
X Ray ◽  
Mixing Method ◽  
Particulate Volume Fraction ◽  
Ti Powder ◽  
Particulate Volume

In situ TiB2/6061 composites have been successfully synthesized through chemical reaction between 6061 master alloy, Al-3B master alloy and Ti powder. The composites fabricated by direct melt mixing method was investigated by Scanning Electron Microscope (SEM), Energy Dispersive x-ray Spectroscopy (EDS) and X-Ray Diffraction (XRD), The results shown the existence of TiB2particles. The size of most TiB2particles were just in micron level, and even reached to sub-micron level. The increase in microhardness and tensile strength for the as-prepared composites with 5% particulate volume fraction (PVF) are up to 26.8% and 51.2% respectively.

Nondestructive method of measurement of laminated plates dielectric parameters

Antennas ◽  
2021 ◽  
Author(s):  
Yu. G. Belov ◽  
V. V. Biryukov ◽  
I. A. Egorov
Keyword(s):  
Dielectric Loss ◽  
Relative Permittivity ◽  
Metal Foil ◽  
Q Factor ◽  
Loss Angle ◽  
Plate Material ◽  
Dielectric Plate ◽  
Electrodynamic Model ◽  
Dielectric Loss Angle ◽  
Electromagnetic Oscillations

The methods for measuring the parameters of dielectric materials of foil plates have been considered. It has been shown that for “non-destructive measurements” (i.e., without removing the metal foil from the dielectric plate), a method based on the excitation of electromagnetic oscillations in a rectangular plate considered as a resonator can be used. Based on the results of measurements of their resonant frequencies and Q-factors, the relative permittivity and the tangent of the dielectric loss angle of the material can be determined. The calculated relations obtained by the authors of the article in one of the early works using the electrodynamic model of a resonator with “magnetic walls” at the ends have been presented. The Q-factor of the resonator has been calculated by the perturbation method, taking into account the losses in the plate dielectric and metallization layers. The results of measurements for four samples from different dielectrics in the frequency range 200...1000 MHz have been presented. The experimental method has been described, in particular, the method of identifying the type of oscillation, the procedure for processing the measurement results. Due to the high sensitivity of the vector analyzer, measurements have been made with a possible small connection of the resonator (metallized plate) with the measuring circuit. This made it possible to minimize the influence of the coupling elements on the measured Qfactor of the oscillations and to consider this Q-factor close to its own. The presented results are in good agreement with the reference data for the materials. The conducted studies have shown the possibility of using a resonator model with “magnetic walls” at the ends for the analysis of electromagnetic oscillations in a foil dielectric plate and, accordingly, using the relations obtained in this case to determine the parameters of the dielectric plate. The conditions for using this model are the small thickness of the plate in comparison with its transverse dimensions and relatively low operating frequencies. The method, which is based on the calculated ratios of the electrodynamic model of the resonator with “magnetic” walls at the ends, provides a sufficiently high accuracy of determining the relative permittivity of the plate material, which led to the use of it (the method) in practice to control the parameters of foil dielectric plates intended for the manufacture of microwave and UHF-band microcircuits. The studies, the results of which have been presented in this paper, allow us to conclude that this method can also be recommended for determining the tangent of the dielectric loss angle of the plate material.

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