scholarly journals Dielectric Breakdown Strength of Polymer Nanocomposites-The Effect of Nanofiller Content

Author(s):  
Markus Takala

<p>Insulation materials can be tailored by compounding nanofillers and polymer materials. The advantageous changes in properties of polymer nanocomposites can be explained by the large interface area of the nanofillers. Theoretical models developed in the field of nanodielectrics concentrate on the analysis of the interface volume.<br />Dielectric breakdown strength (DBS) is one of the most important properties of an insulation material. The DBS of nanocomposites depends heavily on the nanofiller content and even small quantities can cause improvement. This is linked to the maximum interface volume achieved already at low nanofiller concentrations. Homogeneous nanodispersion is the key for DBS increase and reliable results. Often the most profitable nanofiller quantities are below 5 wt-%. The same kind of behaviour can be seen with different voltage shapes, but with dc voltage the increase is bigger. DBS has a maximum value with respect to nanofiller amount and decreases thereafter. Filler quantities around 5 wt-% and even lower are the most attractive considering DBS of nanocomposites.</p>

2018 ◽  
Vol 281 ◽  
pp. 640-645
Author(s):  
Gui Fen Fan ◽  
Hao Yuan Deng ◽  
Meng Meng Hao ◽  
Kai Wang ◽  
Yu Sheng Shi ◽  
...  

Al2O3 ceramics with CaO-SiO2-MgO (CMS), Yb2O3 and ZrO2 additives were fabricated by a conventional solid-state reaction method. The effects of ZrO2 dopant on phase compositions, microwave dielectric properties and dielectric breakdown strength of Al2O3 ceramics were studied. XRD demonstrated that CaAl2Si2O8 and Zr &Y compound phases co-existed with alumina. SEM exhibited that ZrO2 dopant could refine the grain of alumina ceramics and improve its relative density. With ZrO2 content increasing from 1wt% to 5wt% εr increased from 9.8 to 10.25, but Q×f decreased from 52823GHz to 35922GHz. The breakdown strength increased initially and reached the maximum value at ZrO2=3wt%. When ZrO2 content is 3wt%, the comprehensive performances were the best: Eb= 37.37kV/mm for 1mm samples and 17.26kV/mm for 3mm samples, Q×f = 37044 GHz, εr = 10.01, and τf = -52 ppm/°C.


Author(s):  
Muhammad Qusyairie Saari ◽  
Julie Juliewatty Mohamed ◽  
Muhammad Azwadi Sulaiman ◽  
Mohd Fariz Abd Rahman ◽  
Zainal Arifin Ahmad ◽  
...  

2007 ◽  
Vol 62 (5-6) ◽  
pp. 315-323 ◽  
Author(s):  
Gnanaprakasm Little Flower ◽  
Maddireddy Srinivasa Reddy ◽  
Musugu Venkata Ramana Reddy ◽  
Nalluri Veeraiah

PbO-Ga2O3-P2O5 glasses containing different amounts of Cr2O3, ranging from 0 to 1.0 mol%, were prepared. The dielectric properties (viz., constant ε’, loss tanδ , ac conductivity σac over a wide range of frequencies and temperatures, dielectric breakdown strength) have been studied as a function of the concentration of chromium ions. An anomaly has been observed in the dielectric properties of these glasses, when the concentration of Cr2O3 is about 0.4 mol%. This anomaly has been explained in the light of different oxidation states of chromium ions with the aid of data of differential thermal analysis and optical absorption spectra of these glasses.


2015 ◽  
Vol 2015 (CICMT) ◽  
pp. 000116-000120 ◽  
Author(s):  
Takuya Hoshina ◽  
Mikio Yamazaki ◽  
Hiroaki Takeda ◽  
Takaaki Tsurumi

We precisely measured the dielectric breakdown strength of SrTiO3, CaTiO3, and CaZrO3 ceramics as a function of temperature, and revealed the dielectric breakdown mechanism of the ceramics. For the dielectric breakdown test, ceramics specimens with a lot of round-bottom holes were prepared. Using the specimens, the breakdown positions were stabilized and a reliability of breakdown strength was improved as well as the measurement efficiency. As a result of the dielectric breakdown tests, it was found that the dielectric breakdown strength decreased with increasing permittivity at room temperature and the permittivity dependence of breakdown strength obeyed Griffith type energy release rate model. At high temperature above 100ºC, the dielectric breakdown mechanism of SrTiO3 and CaTiO3 ceramics was explained by an intrinsic breakdown model. In contrast, an intrinsic dielectric breakdown of CaZrO3 ceramics didn't occur in the measurement temperature range up to 210ºC. To obtain a high dielectric breakdown strength at high temperature, the dielectric permittivity is required to be low to some extent and the defect concentration of oxygen vacancies should be minimized in the perovskite-structured oxide.


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