METHOD OF PREPARING ELECTROINSULATING COATING Russian patent published in 1998 - IPC

FIELD: electrical industry, more particularly treatment of steel to obtain electroinsulating coatings on surface of steel. SUBSTANCE: composition is applied onto anisotropic electrical steel. Said composition comprises 34.6-42.0 wt % phosphate ions (in terms of P₂O₅); 0.8-1.1 wt % aluminium (Al³⁺); 2.6-3.1 wt % magnesium (Mg²⁺); 0.20-0.24 wt % boron (B₂O₃); and the water balance, the ratio of components being as follows: P₂O₅:(Mg²⁺ Al³⁺)= 8.65-10 and Mg²⁺:Al³⁺=2.6-3. Use of the claimed composition makes it possible to obtain electroinsulating coating with improved physical and mechanical properties, to retain magnetic properties of steel when using equipment, prolong service life of products made of electrical steel under higher humidity conditions. EFFECT: improved properties of the composition. 1 tbl