A method of surface treatments that provide additional characteristics to the surfaces of galvanized steel materials is provided. A chromate-free coating material is applied after texturing on the surface of the galvanizing steel material and obtaining the roughness values. The resulting galvanized steel material provides a stainless-steel alternative sheet materials with high corrosion resistance and anti-fingerprint characteristics.

Disclosed are processes of applying a coating material to galvanized surfaces or materials, which provides significant increases in corrosion resistance. The coating material mentioned herein is applied to the material or surfaces in such a way that the coating can provide the best performance. The obtained coating material is applied to galvanized material or surfaces by making appropriate improvements to the coating material without requiring additional equipment and processes.

Disclosed are processes of applying a coating material to galvanized surfaces or materials, which provides significant increases in corrosion resistance. The coating material mentioned herein is applied to the material or surfaces in such a way that the coating can provide the best performance. The obtained coating material is applied to galvanized material or surfaces by making appropriate improvements to the coating material without requiring additional equipment and processes.

The present application provides a heat exchanger and a manufacturing method of a heat exchanger. The heat exchange includes a metal substrate having a fluid channel for circulating a heat exchange medium. The heat exchanger includes a coating having a rare earth conversion coating and a hydrophilic coating. The rare earth conversion coating is arranged to cover at least part of a surface of the metal substrate, and the rare earth conversion coating includes a rare earth element-containing compound. At least part of the hydrophilic coating is further away from the metal substrate than the rare earth conversion coating. A surface of the heat exchanger is hydrophilic, which is conducive to the discharge of condensate water, and can improve corrosion resistance and prolong a service life of the heat exchanger.

The present application provides a heat exchanger and a manufacturing method of a heat exchanger. The heat exchange includes a metal substrate having a fluid channel for circulating a heat exchange medium. The heat exchanger includes a coating having a rare earth conversion coating and a hydrophilic coating. The rare earth conversion coating is arranged to cover at least part of a surface of the metal substrate, and the rare earth conversion coating includes a rare earth element-containing compound. At least part of the hydrophilic coating is further away from the metal substrate than the rare earth conversion coating. A surface of the heat exchanger is hydrophilic, which is conducive to the discharge of condensate water, and can improve corrosion resistance and prolong a service life of the heat exchanger.

A grain-oriented electrical steel sheet according to one embodiment of the present invention includes a steel sheet and an insulation coating, in which the insulation coating contains a first metal phosphate, which is a metal phosphate of one or two more metals selected from Al, Fe, Mg, Mn, Ni, and Zn; a second metal phosphate, which is a metal phosphate of one or two more metals selected from Co, Mo, V, W, and Zr; and colloidal silica, the insulation coating does not contain chromate, and an elution amount of phosphoric acid of the insulation coating as determined by boiling the grain-oriented electrical steel sheet in a boiled pure water for 10 minutes, then measuring an elution amount of phosphoric acid into the pure water, and dividing the amount of phosphoric acid by the area of the insulation coating of the boiled grain-oriented electrical steel sheet is 30 mg/m.sup.2 or less.

A grain-oriented electrical steel sheet according to one embodiment of the present invention includes a steel sheet and an insulation coating, in which the insulation coating contains a first metal phosphate, which is a metal phosphate of one or two more metals selected from Al, Fe, Mg, Mn, Ni, and Zn; a second metal phosphate, which is a metal phosphate of one or two more metals selected from Co, Mo, V, W, and Zr; and colloidal silica, the insulation coating does not contain chromate, and an elution amount of phosphoric acid of the insulation coating as determined by boiling the grain-oriented electrical steel sheet in a boiled pure water for 10 minutes, then measuring an elution amount of phosphoric acid into the pure water, and dividing the amount of phosphoric acid by the area of the insulation coating of the boiled grain-oriented electrical steel sheet is 30 mg/m.sup.2 or less.

A method for treating and phosphatizing a metal board without using acid includes the following steps: performing a degreasing step to remove grease and dirt from a surface of the metal board with a degreasing agent; performing a blast-peening step by blasting and peening polygon blast-peening granules on the metal board through a centrifugal impeller to remove an oxidized layer; performing a washing step to clean remaining powders from the metal board after the blast-peening step; performing a phosphatizing step to form a protective phosphate coating on the metal board; performing another washing step to wash off remaining phosphatizing agents from the metal board; performing a rustproofing step to apply a rustproofing agent on the metal board; and performing a drying step to dry the metal board.

A grain-oriented electrical steel sheet includes: a base steel sheet having a predetermined chemical composition; a glass coating provided on the surface of the base steel sheet; and a tension-applying insulation coating provided on the surface of the glass coating, in which linear thermal strains having, a predetermined angle (r) with respect to a transverse direction which is a direction orthogonal to a rolling direction are periodically formed on the surface of the tension-applying insulation coating at predetermined intervals along the rolling direction, a full width at half maximum Fl on the linear thermal strain and a full width at half maximum F2 at an intermediate position between the two linear thermal strains adjacent to each other satisfy 0.00<(F1F2)/F20.15, the width of the linear thermal strain is 10 m or more and 300 m, or less, and in the base steel sheet, an orientation distribution angle around a rolling direction axis of secondary recrystallization grains, an orientation distribution angle around an axis parallel to a normal direction. and an orientation distribution angle around an axis perpendicular to each of the RD axis and the ND axis in units of satisfy 1.08.0 and 0.0(.sup.2+.sup.2).sup.0.510.0.

Aqueous compositions useful as a passivation treatment prior to painting to reduce corrosion. The compositions includes water, a trivalent chromium salt with the formula Cr(H.sub.xPO.sub.4).sub.3, where x is 1.5 or 2, a polymer system having a plurality of carboxylic functional groups, an organo-functional silane, and an organopolyphosphonic acid. A process for treating a metal surface includes contacting the surface with such aqueous compositions. The compositions and the processes provide benefits in comparison to the zinc phosphate metal pretreatment thought to be the standard in the industry.