A coating with strong adhesion for medical magnesium alloys, including a magnesium phosphate or calcium phosphate layer as an inner layer and a hydrophobic polymer layer as an outer layer. The inner layer is attached to the medical magnesium alloy; and the outer layer is attached to the inner layer. A preparation method of the coating is also provided, including: (S1) carrying out surface treatment on a medical magnesium alloy substrate; (S2) preparing a solution including magnesium salt/calcium salt and phosphoric acid/phosphate followed by pH adjustment and heating; (S3) soaking the medical magnesium alloy substrate in the solution followed by washing and drying to obtain a magnesium phosphate/calcium phosphate layer-coated medical magnesium alloy sample; and (S4) depositing a hydrophobic polymer layer on the medical magnesium alloy sample through chemical vapor deposition (CVD).

A coating with strong adhesion for medical magnesium alloys, including a magnesium phosphate or calcium phosphate layer as an inner layer and a hydrophobic polymer layer as an outer layer. The inner layer is attached to the medical magnesium alloy; and the outer layer is attached to the inner layer. A preparation method of the coating is also provided, including: (S1) carrying out surface treatment on a medical magnesium alloy substrate; (S2) preparing a solution including magnesium salt/calcium salt and phosphoric acid/phosphate followed by pH adjustment and heating; (S3) soaking the medical magnesium alloy substrate in the solution followed by washing and drying to obtain a magnesium phosphate/calcium phosphate layer-coated medical magnesium alloy sample; and (S4) depositing a hydrophobic polymer layer on the medical magnesium alloy sample through chemical vapor deposition (CVD).

An electrical steel sheet (1) includes a base material (2) of electrical steel, and an insulating film (3) formed on a surface of the base material (2). Three conditions (1.8≦3[Fe]/[P]+Σn.sub.M[M]/[P]≦3.6, 0.6≦Σn.sub.M[M]/[P]≦2.4, and 0.6≦3[Fe]/[P]≦2.4) are satisfied in a region of 50 area % or more of a cross section parallel to a thickness direction of the insulating film. [Fe] denotes a proportion (atom %) of Fe, [P] denotes a proportion (atom %) of P, [M] denotes a proportion (atom %) of each of Al, Zn, Mg and Ca, and n.sub.M denotes a valence of each of Al, Zn, Mg and Ca.

An electrical steel sheet (1) includes a base material (2) of electrical steel, and an insulating film (3) formed on a surface of the base material (2). Three conditions (1.8≦3[Fe]/[P]+Σn.sub.M[M]/[P]≦3.6, 0.6≦Σn.sub.M[M]/[P]≦2.4, and 0.6≦3[Fe]/[P]≦2.4) are satisfied in a region of 50 area % or more of a cross section parallel to a thickness direction of the insulating film. [Fe] denotes a proportion (atom %) of Fe, [P] denotes a proportion (atom %) of P, [M] denotes a proportion (atom %) of each of Al, Zn, Mg and Ca, and n.sub.M denotes a valence of each of Al, Zn, Mg and Ca.

An electrical steel sheet (1) includes a base material (2) of electrical steel, and an insulating film (3) formed on a surface of the base material (2), the insulating film (3) containing a polyvalent metal phosphate and Fe. A maximum value of a parameter Q expressed by “Q=C.sub.Fe—O/C.sub.P” is equal to or less than 1.3 times an average value of the parameter Q in a region from a first depth from a surface of the insulating film to a second depth, C.sub.Fe—O denoting a proportion (atom %) of Fe bonded to O relative to all elements, and C.sub.P denoting a proportion (atom %) of P relative to all elements. The first depth is 20 nm from the surface, and the second depth is a depth where the proportion of P is equal to a proportion of metal Fe.

An electrical steel sheet (1) includes a base material (2) of electrical steel, and an insulating film (3) formed on a surface of the base material (2). The insulating film (3) contains a phosphate of one or more selected from the group consisting of Al, Zn, Mg and Ca. A proportion of an amount by mole (mol) of Fe atoms relative to an amount by mole (mol) of P atoms in the insulating film (3) is more than 0.1 nor more than 0.65.

An electrical steel sheet (1) includes a base material (2) of electrical steel, and an insulating film (3) formed on a surface of the base material (2). The insulating film (3) contains a phosphate of one or more selected from the group consisting of Al, Zn, Mg and Ca. A proportion of an amount by mole (mol) of Fe atoms relative to an amount by mole (mol) of P atoms in the insulating film (3) is more than 0.1 nor more than 0.65.

An electrical steel sheet (1) includes a base material (2) of electrical steel, and an insulating film (3) formed on a surface of the base material (2). The insulating film (3) contains a phosphates of one or more selected from the group consisting of Al, Zn, Mg and Ca. The phosphate exhibits a specific peak having a top within a range of −26 ppm to −16 ppm in a solid .sup.31P-NMR spectrum, and a proportion of an integrated intensity of the specific peak relative to an integrated intensity of all peaks in the solid .sup.31P-NMR spectrum is 30% or more.

An electrical steel sheet (1) includes a base material (2) of electrical steel, and an insulating film (3) formed on a surface of the base material (2). The insulating film (3) contains a phosphates of one or more selected from the group consisting of Al, Zn, Mg and Ca. The phosphate exhibits a specific peak having a top within a range of −26 ppm to −16 ppm in a solid .sup.31P-NMR spectrum, and a proportion of an integrated intensity of the specific peak relative to an integrated intensity of all peaks in the solid .sup.31P-NMR spectrum is 30% or more.

The present invention relates to a composition for forming an insulation coating film of an oriented electrical steel sheet, including a first component (A) including a composite metal phosphate, a derivative thereof, or a mixture thereof, and a second component (B) including at least two colloidal silicas having different average particle diameters, a method for forming an insulation coating film using the same, and an oriented electrical steel sheet having an insulation coating film formed thereon.