Electrical Properties. Aluminum oxide and its alloys can be used as electrical insulators. The high temperature stability of the coating permits operation up to 500C. Anodic coatings typically exhibit a voltage breakdown of 2,000-3,000 v/mil, a dielectric constant of 7.4-7.6 and resistivity from 1014 ohm cm to 200C. This resistivity is of the same order of magnitude as glass and porcelain.