Abstract: A process for providing a metal oxide-containing coating on a compatible substrate, the coating being transparent to a photocuring source output and upon cure being resistant to electrical stress. The process of the invention comprises a) preparing a precursor composition comprising a mixture of a stabilizer and a metal oxide sol precursor material; b) combining the stabilizer/metal oxide sol precursor material mixture with a photocurable base resin without high shear mixing to achieve a homogeneous, transparent composition; c) coating the substrate material with the transparent composition; and d) photocuring the coated substrate bearing the transparent composition, wherein the cured coating is homogenous and transparent and remains transparent in the use state, thereby rendering the coating corona resistant. This invention further relates to the coated substrate.

Abstract: A magnetic top stick for use at the opening portion of a core slot of an electromagnetic device includes a group of magnetically anisotropic members arranged in a substantially non-magnetic body adapted to fit snugly within the core slot. The magnetic properties of the group of members combine to provide the top stick with an overall high magnetic permeability in the depth direction of the core slot and overall low magnetic permeabilities in the width and longitudinal directions of the core slot. A convenient method of manufacturing the top stick includes first forming magnetically anisotropic sheets by cold rolling and annealing, then laminating and heat processing the sheets with B stage materials to generate a unitary laminated structure. The unitary laminated structure is sectioned into multiple magnetic flux bars which are in turn disposed in the non-magnetic body forming the top stick.