The present invention relates to methods and compositions for coating ferrous metal substrates. In an embodiment, the invention includes a composition for forming a magnetite coating on a ferrous metal substrate. The composition comprising an aqueous oxidizing solution. The aqueous oxidizing solution comprising an alkali metal hydroxide, an alkanolamine, and a chloride salt. In an embodiment, the invention includes a method of forming a magnetite coating on a ferrous metal substrate. The method including contacting the ferrous metal substrate with an aqueous oxidizing solution, the aqueous oxidizing solution comprising an alkali metal hydroxide, an alkanolamine, and a chloride salt. Other embodiments are also included herein.

The present invention relates to methods and compositions for coating ferrous metal substrates. In an embodiment, the invention includes a composition for forming a magnetite coating on a ferrous metal substrate. The composition comprising an aqueous oxidizing solution. The aqueous oxidizing solution comprising an alkali metal hydroxide, an alkanolamine, and a chloride salt. In an embodiment, the invention includes a method of forming a magnetite coating on a ferrous metal substrate. The method including contacting the ferrous metal substrate with an aqueous oxidizing solution, the aqueous oxidizing solution comprising an alkali metal hydroxide, an alkanolamine, and a chloride salt. Other embodiments are also included herein.

An annealing separator composition for a grain-oriented electrical steel sheet according to an exemplary embodiment of the present invention contains a composite metal oxide containing Mg and a metal M, wherein the metal M is one or more of Be, Ca, Ba, Sr, Sn, Mn, Fe, Co, Ni, Cu, and Zn.

Provided is a surface hardening method for surface hardening a sulfuric acid-anodized aluminum alloy oxide layer, which includes: pre-treatment in which various foreign substances, including an oxide film, attached to a surface of an aluminum alloy are removed; sealing treatment in which the aluminum alloy having been subjected to the pre-treatment is immersed in a sealing solution, whereby fine pores formed in a film are sealed; and heat treatment in which the aluminum alloy having been subjected to the sealing treatment is charged to, and thermally treated in, a heat treatment furnace and then naturally cooled. By lowering the withstand voltage of an aluminum alloy oxide layer and increasing the hardness by subjecting the same to sealing treatment and subsequent post-heat treatment, the present invention has the effect of providing an environmentally-friendly and crack-free lightweight material that can replace steel products.

Provided is a surface hardening method for surface hardening a sulfuric acid-anodized aluminum alloy oxide layer, which includes: pre-treatment in which various foreign substances, including an oxide film, attached to a surface of an aluminum alloy are removed; sealing treatment in which the aluminum alloy having been subjected to the pre-treatment is immersed in a sealing solution, whereby fine pores formed in a film are sealed; and heat treatment in which the aluminum alloy having been subjected to the sealing treatment is charged to, and thermally treated in, a heat treatment furnace and then naturally cooled. By lowering the withstand voltage of an aluminum alloy oxide layer and increasing the hardness by subjecting the same to sealing treatment and subsequent post-heat treatment, the present invention has the effect of providing an environmentally-friendly and crack-free lightweight material that can replace steel products.

A permanent magnet may include a Fe.sub.16N.sub.2 phase in a strained state. In some examples, strain may be preserved within the permanent magnet by a technique that includes etching an iron nitride-containing workpiece including Fe.sub.16N.sub.2 to introduce texture, straining the workpiece, and annealing the workpiece. In some examples, strain may be preserved within the permanent magnet by a technique that includes applying at a first temperature a layer of material to an iron nitride-containing workpiece including Fe.sub.16N.sub.2, and bringing the layer of material and the iron nitride-containing workpiece to a second temperature, where the material has a different coefficient of thermal expansion than the iron nitride-containing workpiece. A permanent magnet including an Fe.sub.16N.sub.2 phase with preserved strain also is disclosed.

A permanent magnet may include a Fe.sub.16N.sub.2 phase in a strained state. In some examples, strain may be preserved within the permanent magnet by a technique that includes etching an iron nitride-containing workpiece including Fe.sub.16N.sub.2 to introduce texture, straining the workpiece, and annealing the workpiece. In some examples, strain may be preserved within the permanent magnet by a technique that includes applying at a first temperature a layer of material to an iron nitride-containing workpiece including Fe.sub.16N.sub.2, and bringing the layer of material and the iron nitride-containing workpiece to a second temperature, where the material has a different coefficient of thermal expansion than the iron nitride-containing workpiece. A permanent magnet including an Fe.sub.16N.sub.2 phase with preserved strain also is disclosed.

Disclosed is a method for manufacturing high-carbon bearing steel, which include: heating a billet at a temperature of about 950 to 1,050° C. for about 70 to 120 minutes, rolling the billet to manufacture a wire rod, winding the wire rod to manufacture a wire rod coil, cooling the wire rod coil, and subsequently heat treating the wire rod coil for spheroidizing and carbonitriding, respectively. The bearing steel may include an amount of about 0.9 to 1.3 wt % of carbon (C), an amount of about 1.1 to 1.6 wt % of silicon (Si), an amount of about 1.0 to 1.5 wt % of manganese (Mn), an amount of about 1.5 to 1.9 wt % of chromium (Cr), an amount of about 0.2 to 0.6 wt % of nickel (Ni), an amount of about 0.1 to 0.3 wt % of molybdenum (Mo), and the balance iron (Fe) based on the total weight thereof.

Disclosed is a method for manufacturing high-carbon bearing steel, which include: heating a billet at a temperature of about 950 to 1,050° C. for about 70 to 120 minutes, rolling the billet to manufacture a wire rod, winding the wire rod to manufacture a wire rod coil, cooling the wire rod coil, and subsequently heat treating the wire rod coil for spheroidizing and carbonitriding, respectively. The bearing steel may include an amount of about 0.9 to 1.3 wt % of carbon (C), an amount of about 1.1 to 1.6 wt % of silicon (Si), an amount of about 1.0 to 1.5 wt % of manganese (Mn), an amount of about 1.5 to 1.9 wt % of chromium (Cr), an amount of about 0.2 to 0.6 wt % of nickel (Ni), an amount of about 0.1 to 0.3 wt % of molybdenum (Mo), and the balance iron (Fe) based on the total weight thereof.

A grain-oriented electrical steel sheet that includes a base coating with a high TiN ratio advantageous for the application of tension to the steel sheet and has excellent magnetic property is provided. The grain-oriented electrical steel sheet includes: a base coating having a peak value PTiN of TiN in the form of osbornite, observed in a range of 42°<2θ<43° and a peak value PMg.sub.2SiO.sub.4 of Mg.sub.2SiO.sub.4 in the form of forsterite, observed in a range of 35°<2θ<36° of both more than 0 and satisfying a relationship PTiN≧PMg.sub.2SiO.sub.4, in thin-film X-ray diffraction analysis; and an iron loss W.sub.17/50 of 1.0 W/kg or less.