Abstract
In this study, the DC conductivity from low electric
fields up to breakdown fields is studied for several
different thermally sprayed ceramic coatings. Although
the DC conductivity of bulk alumina ceramic has been
observed to follow the space charge limited current
conduction mechanism, the studied ceramic coatings do not
follow or follow only partly this mechanism. Possible
reason for this is their different microstructure since
bulk alumina exhibits fully crystalline microstructure
while the ceramic coating consists of crystalline and
amorphous regions as well as voids, defects and numerous
interfaces. A possible conduction mechanism of the
ceramic coatings based on the different conductivities of
the amorphous and crystalline regions of the coatings is
proposed. The microstructural features (e.g. volumetric
porosity) are found to affect the breakdown strength for
some of the studied coatings. The step-test breakdown
strengths of the coatings were lower than the ramp-test
ones due to the longer stress durations in step tests
giving an indication of effects of electrical stress
duration and possible short-term degradation of the
coatings.
| Original language | English |
|---|---|
| Article number | 7873508 |
| Pages (from-to) | 499-510 |
| Journal | IEEE Transactions on Dielectrics and Electrical Insulation |
| Volume | 24 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 2017 |
| MoE publication type | A1 Journal article-refereed |
Keywords
- spinel
- dielectric breakdown
- conductivity
- thermally sprayed ceramic coating
- alumina
- ProperTune