Rust Bullet Coating Dielectric Strength
Dielectric Strength of Coatings By Kathline Spring
* The dielectric strength of an insulating material (i.e. Fully Cured Rust Bullet Coating) is the maximum electric field strength (i.e. 25kV, etc.) that it can withstand intrinsically without breaking down (experiencing failure of its insulating properties)
* The ASTM D-149 measures a materials dielectric strength. The higher the dielectric strength the better the ability to resist voltage breakdown.
* Good Insulators have high dielectric strength
* High dielectric strength correlates to high corrosion inhibiting functions
* Breakdowns occur abruptly (within nanoseconds) resulting in the formation of an electrically conductive path and a disruptive discharge through the material. For solids (such as a cured Rust Bullet Coating) breakdown events severely degrade or destroys insulating capability
* Dielectric strength increases with increase in thickness of coating (directly proportional)
* Dielectric strength decreases with increase of operating temperature (inversely proportionable)
* Dielectric strength decreases with increase in frequency (inversely proportionable)
* Dielectric strength decreases with increase in humidity (inversely proportionable)
* The Dielectric Strength of Alumina (Aluminum Oxide) is 13.4MV/m
* Holiday (Pinhole) Detectors can be used to determine dielectric strength
* ASTM D-257 measures the surface resistivity of a material
* Surface resistivity is the resistance to leakage current along the surface of an insulating material
* Volume resistivity is the resistance to leakage current through the body of the insulting material
* The higher the surface/volume resistivity, the lower the leakage current and the less conductive the material
* Good insulator = Good dielectric strength = Good conductivity
