Options
2011
Conference Paper
Titel
Comparison of the electrical properties of Al3O3 sprayed coatings from feedstock powders and aqueous suspensions
Abstract
In this paper the characteristics (microstructure, phase compns.) and elec. insulating properties of thermally sprayed alumina coatings produced by suspension-HVOF (S-HVOF) process and conventional HVOF spray method are compared. The elec. resistance (elec. resistivity) and dielec. strength were investigated using DC-elec. resistance measurements, electrochem. impedance spectroscopy (EIS) and dielec. breakdown test. The elec. resistance was detd. at room temp. at different relative air humidity (RH) levels, from 6% RH up to 97% RH. Differences in the elec. insulating properties due to the different coating characteristics are discussed. The suspension-sprayed Al2O3 coatings showed better elec. resistance stability at high humidity levels (> 75% RH), which could be explained by a spec ific microstructure and retention of a higher content of a-Al2O3. Nonetheless, the values of dielec. breakdown voltage and dielec. strength recorded for suspension sprayed coatings were lower than those of HVOF coatings.