The method for manufacturing a grain-oriented electrical steel sheet is a method for manufacturing a grain-oriented electrical steel sheet including a strain region forming process of irradiating the grain-oriented electrical steel sheet having a base steel sheet (1), an intermediate layer (4) disposed to be in contact with the base steel sheet (1), and an insulation coating (3) disposed to be in contact with the intermediate layer (4) with an electron beam and forming a strain region (D) which extends in a direction intersecting a rolling direction of the base steel sheet (1) on a surface of the base steel sheet (1), wherein, in the strain region forming process, a temperature of a central portion of the strain region (D) in the rolling direction of the base steel sheet (1) and an extension direction of the strain region (D) is heated to 800° C. or higher and 2000° C. or lower.

An electrical steel sheet provided with an insulating coating is disclosed. Therefore, a pre-treatment liquid used on an electrical steel sheet having a forsterite coating on a surface thereof is provided before applying an insulating coating treatment liquid containing at least one salt selected from the group consisting of phosphate, borate, and silicate, the pre-treatment liquid. The pre-treatment liquid includes: at least one inorganic acid selected from the group consisting of hydrochloric acid, sulfuric acid, and phosphoric acid; and acetic acid, wherein a content of the acetic acid is not less than 1 mass ppm and not more than 3000 mass ppm.

A grain-oriented magnetic steel sheet with chromium-free insulating tension coating includes a grain-oriented magnetic steel sheet and an insulating tension coating containing a phosphate salt and silica on a surface of the grain-oriented magnetic steel sheet, the coating further including a crystalline compound represented by the general formula (1): M.sup.II.sub.3M.sup.III.sub.4(X.sup.VO.sub.4).sub.6 . . . (1). A method for producing a grain-oriented magnetic steel sheet with chromium-free insulating tension coating includes applying an insulating tension coating liquid to a surface of a finish annealed grain-oriented magnetic steel sheet, the coating liquid including colloidal silica, a phosphate salt and a metal element M-containing compound in a specific ratio, and heat treating the steel sheet at least one time at a temperature of not less than 900° C. in an atmosphere including a non-oxidizing gas and having a dew point of not more than 0° C.

Disclosed is a heat exchange tube of waste heat boiler, which includes a tube body. The outer surface of the tube body is sprayed with a layer of anti-corrosion coating. The components of the anti-corrosion coating are Al.sub.2O.sub.3, CaAl.sub.2O.sub.4 and Ca.sub.3(PO.sub.4).sub.2. On the surface of nano anti-corrosion coating, HF reacts with Al.sub.2O.sub.3, CaAl.sub.2O.sub.4 and Ca.sub.3(PO.sub.4).sub.2 to form AlF.sub.3 and Ca.sub.5(PO.sub.4).sub.3F, which are tightly wrapped on the surface of the coating, thereby effectively preventing HF from corroding the interior of the coating and the heat exchange tube. Meanwhile, due to the anti-corrosion coating with the specific composition of the present disclosure, the heat exchange tube of the present disclosure can be resistant to fluorine corrosion at a high temperature of 600° C. or more, and can be used at a rather high temperature of 1000° C. or more.

A solution for forming an insulation coating of grain-oriented electrical steel sheet includes an aqueous solution prepared by mixing a phosphate solution and colloidal silica. Chromium is not added to the aqueous solution. The colloidal silica includes silica particles surface-modified by an aluminate or is prepared by adding an aluminate to colloidal silica such as conventional colloidal silica.

A solution for forming an insulation coating of grain-oriented electrical steel sheet includes an aqueous solution prepared by mixing a phosphate solution and colloidal silica. Chromium is not added to the aqueous solution. The colloidal silica includes silica particles surface-modified by an aluminate or is prepared by adding an aluminate to colloidal silica such as conventional colloidal silica.

Described herein is a composition including at least one polyurethane polymer. Also described herein are a method of using the composition including at least one polyurethane polymer for metal pre-treatment and a process for metal pre-treatment.

The invention relates to a multiple-step method for the corrosion-protective pretreatment of components, said pretreatment being at least partially produced from a metal material predominantly consisting of at least one of the elements iron zinc and/or aluminium, according to which the components are first brought into contact with an acid aqueous composition (A) containing water-soluble compounds of the elements Zr and/or Ti and then with an acid aqueous composition (B) containing phosphate ions and an accelerator. The method is particularly suitable for the pretreatment before an electrocoating.

Disclosed is a heat exchange tube of waste heat boiler, which includes a tube body. The outer surface of the tube body is sprayed with a layer of anti-corrosion coating. The components of the anti-corrosion coating are Al.sub.2O.sub.3, CaAl.sub.2O.sub.4 and Ca.sub.3(PO.sub.4).sub.2. On the surface of nano anti-corrosion coating, HF reacts with Al.sub.2O.sub.3, CaAl.sub.2O.sub.4 and Ca.sub.3(PO.sub.4).sub.2 to form AlF.sub.3 and Ca.sub.5(PO.sub.4).sub.3F, which are tightly wrapped on the surface of the coating, thereby effectively preventing HF from corroding the interior of the coating and the heat exchange tube. Meanwhile, due to the anti-corrosion coating with the specific composition of the present disclosure, the heat exchange tube of the present disclosure can be resistant to fluorine corrosion at a high temperature of 600° C. or more, and can be used at a rather high temperature of 1000° C. or more.

The grain-oriented electrical steel sheet according to the present invention is a grain-oriented electrical steel sheet having a base steel sheet (1), an intermediate layer (4) disposed to be in contact with the base steel sheet (1), and an insulation coating (3) disposed to be in contact with the intermediate layer (4), and the grain-oriented electrical steel sheet includes a surface of the base steel sheet (1) having a groove (G) which extends in a direction intersecting a rolling direction of the base steel sheet (1), in which in a cross-sectional view of a plane parallel to the rolling direction and a sheet thickness direction of the base steel sheet (1), when a region between end portions of the groove (G) is defined as a groove part (R.sub.G), an average thickness of the intermediate layer (4) of the groove part (R.sub.G) is 0.5 times or more and 3.0 times or less an average thickness of the intermediate layer (4) other than the groove part (R.sub.G), and an area ratio of voids in the insulation coating (3) of the groove part (R.sub.G) is 15% or less.