Abstract: An aqueous coating solution for forming an insulative coating directly on electrical steels and on steels having a mill glass thereon. The aqueous solution comprises an aluminum-magnesium phosphate premix solution and a colloidal silica solution. The premix solution also comprises from about 10 to about 45 parts by weight Cr.sub.2 O.sub.3 for every 100 parts by weight H.sub.2 PO.sub.4.sup.- calculated as H.sub.3 PO.sub.4 on a water-free basis, from about 5 to about 20 parts of a compound chosen from the class consisting of boric acid, vanadium pentoxide and mixtures thereof per 100 parts H.sub.2 PO.sub.4.sup.- calculated as H.sub.3 PO.sub.4 on a water-free basis and additional Mg.sup.++ up to that amount which will go into solution. The colloidal silica solution is present in an amount of from that amount which will form a good glass up to 40 volume percent to provide a coating solution having a premix solution to colloidal silica solution volume ratio up to 1.5:1.

Abstract: An aqueous magnesia slurry for forming an insulative glass coating on silicon steel, wherein a substantial portion of the magnesia is inactive (a citric acid activity greater than 200 seconds), a decomposable phosphate compound is present within the range of 2% to 25% by weight calculated as P.sub.2 O.sub.5, based on the dry weight of magnesia, and the magnesia concentration is at least 0.24 grams per cubic centimeter of slurry. The slurry is stable against settling for up to 10 hours and has a desirable viscosity for coating application by conventional means. From 10% to 100% inactive magnesia may be used with the remainder an active magnesia (citric acid activity of 20 to 40 seconds). Preferred phosphate compounds include monocalcium phosphate monohydrate, water soluble ammonium polyphosphate and dicalcium phosphate dihydrate.

Abstract: A process of producing an electrically insulative glass film on cold reduced silicon steel strip or sheet stock which will have a magnetic permeability greater than 1850 at 796 A/m after a final high temperature anneal which develops cube-on-edge orientation, which comprises applying an aqueous slurry containing magnesia, at least one boron compound, and up to 20% titanium dioxide, based on the weight of magnesia, drying the coating, and subjecting the coated stock to said final anneal, the total boron content being proportioned within the range of about 0.07% to about 0.30%, based on the weight of magnesia, in accordance with any two of the three parameters: particle size distribution, citric acid activity, and surface area, i.e., inversely to the bulk density of the dried coating. Improved core loss characteristics are obtained without sacrifice of permeability values.

Abstract: A method of improving the surface insulation resistance of electrical steels having an insulative coating thereon by subjecting the electrical steels to electrochemical treatment as part of the routing thereof, to remove small metallic nodules, particles and the like extending through or protruding above the insulative coating. Following the electrochemical treatment, the electrical steels are rinsed and dried.