3. Coating formation and electrical insulation

The grain-oriented electrical sheet is coated to provide electrical insulation on both sides. The coating process starts with decarburization step No. 5, followed by closed vessel annealing step No. 6, and is completed on coating and leveling line No. 7 (figure 2 ).

This coating, with a thickness of around 3 μm per side, consists of an inorganic film of magnesium silicates (glass film) onto which a second film of inorganic constituents based on phosphates and silicates has been deposited. This insulation configuration is known as EC-5 on EC-2 according to EN 10342.

The insulation coating must be sufficiently...