Anodizing of high electrically stressed components

Anodizing creates an aluminum oxide coating that penetrates into the surface as well as builds above the surface of aluminum, creating a very hard ceramic type coating with good dielectric properties. Electrical carrying components (or spool in this case) located in the high vacuum rod-pinch diode section of an x-ray producing machine over time and usage experience electrical breakdown, thus yielding undesirable x-ray dosages or failure. Machine operators have recorded decreases in x-ray dosages over numerous shots using the reusable spool component; re-anodizing the interior surface of the spool did not provide improvements as expected. Machine operation subject matter expert deployed coating the anodized surface with vacuum oil to eliminate electrical breakdown as a temporary fix. It is known that an anodized surface is very porous and it is because of this porosity that the surface has the ability to trap air, which electrically is a catalyst for electrical breakdown. In this paper we present this field solution to eliminating electrical breakdown of the electrical carrying spool component by oiling. We will also present results of surface anodizing improvements by surface finish preparation and surface sealing. We will also present similarity of oiling the anodized surface to anodized hot dip sealing.