Dielectric Breakdown Strength of Thermally Sprayed Ceramic Coatings: Effects of Different Test Arrangements

2015 ◽  
Vol 24 (3) ◽  
pp. 542-551 ◽  
Author(s):  
Minna Niittymäki ◽  
Kari Lahti ◽  
Tomi Suhonen ◽  
Jarkko Metsäjoki
Keyword(s):  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Ceramic Coatings ◽  
Dielectric Breakdown Strength ◽  
Thermally Sprayed

scholarly journals Effects of Ambient Conditions on the Dielectric Properties of Thermally Sprayed Ceramic Coating

2018 ◽  
Author(s):  
M Niittymäki ◽  
B. Rotthier ◽  
K. Lahti ◽  
T. Suhonen ◽  
J Metsäjoki
Keyword(s):  
Dielectric Properties ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Thermal Spraying ◽  
Ceramic Coatings ◽  
Alumina Coating ◽  
Ambient Conditions ◽  
Coating Materials ◽  
Sprayed Coating ◽  
Thermally Sprayed

<p>Thermal spraying techniques are used to manufacture insulating coatings especially for demanding applications like fuel cells where normal insulating materials cannot be used. In electrical insulation applications, the mostly used coating materials are aluminum oxide (Al2O3), magnesium oxide (MgO) and magnesium aluminate (MgAl2O4). Dielectric properties of thermally sprayed ceramic coatings are strongly affected by ambient conditions, and in addition to this they are not well documented in the literature. In this paper the effects of environmental conditions on certain dielectric properties of a thermally sprayed coating are studied. DC resistivity as well as permittivity and losses at different frequencies at relative humidities of 20 % and 45 % at temperature of 20 °C, 40 °C and 60 °C will be reported in the paper for Al2O3 samples sprayed using HVOF (High Velocity Oxygen Fuel) technique. DC dielectric breakdown strength is also studied for the HVOF alumina coating at temperature of 20 °C and relative humidity of 20 %. Effects of ambient conditions and coating material composition are also analyzed.</p>

scholarly journals DC Dielectric Breakdown Behavior of Thermally Sprayed Ceramic Coatings

2017 ◽  
Author(s):  
Minna Niittymäki ◽  
Tomi Suhonen ◽  
Jarkko Metsäjoki ◽  
Kari Lahti
Keyword(s):  
Electric Field ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Strong Dependence ◽  
Degradation Process ◽  
Ceramic Coatings ◽  
Alumina Coating ◽  
Dc Resistivity ◽  
Ramp Rate ◽  
Thermally Sprayed

<p>Previous studies of dielectric properties of thermally sprayed insulating ceramic coatings are focused on linearly ramped dielectric breakdown strength as well as<br />DC resistivity, relative permittivity and dielectric loss characterizations. However, reports of the effects of ramp rate or of any kind of long term stressing on the breakdown strength cannot be found in literature. The aim of this paper was to study the DC breakdown behavior of one type of HVOF sprayed alumina coating under different stresses. It can be concluded that the ramp rate of DC breakdown measurement has no remarkably influence on the breakdown strength. The breakdown behavior was also studied using step-by-step tests with two constant step voltages and step durations. The DC resistivity of the alumina coating showed strong dependence on the applied electric field. The resistivity behaved ohmicly below the field strength of ~0.5 V/μm and above ~8…12 V/μm, however, the resistivity decreased approximately three decades in the nonohmic region (0.5 V/μm --&gt;). At electric field strengths above ~25 V/μm, the degradation started in the material leading to breakdown. However, when the step duration was longer (60 min), the degradation process started already slightly below the applied field of 25 V/μm.</p>

scholarly journals Dielectric Breakdown Strength and Energy Storage Density of CCTO-ZBS Electroceramic

2020 ◽  
Vol 596 ◽  
pp. 012006
Author(s):  
Muhammad Qusyairie Saari ◽  
Julie Juliewatty Mohamed ◽  
Muhammad Azwadi Sulaiman ◽  
Mohd Fariz Abd Rahman ◽  
Zainal Arifin Ahmad ◽  
...  
Keyword(s):  
Energy Storage ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Energy Storage Density ◽  
Dielectric Breakdown Strength ◽  
Storage Density

Influence of Chromium Ions on the Dielectric Properties of the PbO-Ga2O3-P2O5 Glass System

2007 ◽  
Vol 62 (5-6) ◽  
pp. 315-323 ◽  
Author(s):  
Gnanaprakasm Little Flower ◽  
Maddireddy Srinivasa Reddy ◽  
Musugu Venkata Ramana Reddy ◽  
Nalluri Veeraiah
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Dielectric Properties ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Oxidation States ◽  
Optical Absorption Spectra ◽  
Dielectric Breakdown Strength ◽  
Chromium Ions ◽  
Wide Range

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.

Dielectric Breakdown Mechanism of Perovskite-Structured Ceramics

2015 ◽  
Vol 2015 (CICMT) ◽  
pp. 000116-000120 ◽  
Author(s):  
Takuya Hoshina ◽  
Mikio Yamazaki ◽  
Hiroaki Takeda ◽  
Takaaki Tsurumi
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Oxygen Vacancies ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Dielectric Breakdown Strength ◽  
Breakdown Mechanism ◽  
High Dielectric ◽  
Measurement Efficiency ◽  
Breakdown Model

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.

Dielectric breakdown strength of alumina ceramics reinforced by fractal dendritic Ca9Al(PO4)7 as the second crystalline phase

2020 ◽  
Vol 832 ◽  
pp. 154811
Author(s):  
Wei Xu ◽  
Pengping Li ◽  
Chenyang Zhang ◽  
Mingfeng Zhong ◽  
Yatao Shao ◽  
...  
Keyword(s):  
Crystalline Phase ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Alumina Ceramics ◽  
Dielectric Breakdown Strength
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