Provided is a treatment solution for chromium-free tension coating that can simultaneously achieve excellent moisture absorption resistance and a high iron loss reduction effect obtained by imparting sufficient tension, by using an inexpensive Ti source instead of expensive Ti chelate. The treatment solution for chromium-free tension coating contains: one or more of phosphates of Mg, Ca, Ba, Sr, Zn, Al, and Mn; colloidal silica in an amount of 50 parts by mass to 120 parts by mass per 100 parts by mass of the phosphate in terms of solid content of SiO.sub.2; Ti source in an amount of 30 parts by mass to 50 parts by mass per 100 parts by mass of the phosphate in terms of solid content of TiO.sub.2; and H.sub.3PO.sub.4, and the number of moles of metallic elements in the phosphate and of phosphorus in the treatment solution satisfy:
0.20?([Mg]+[Ca]+[Ba]+[Sr]+[Zn]+[Mn]+1.5[Al])/[P]?0.45(1).

Described herein is a method for substantially nickel-free phosphating of a metallic surface, wherein a metallic surface, optionally after cleaning and/or activation, is first treated with an acidic aqueous phosphating composition that includes zinc ions, manganese ions, and phosphate ions, and is optionally rinsed and/or dried, and is thereafter treated with an aqueous after-rinse composition that includes at least one kind of metal ion selected from the group consisting of the ions of molybdenum, copper, silver, gold, palladium, tin, antimony, titanium, zirconium, and hafnium and/or at least one polymer selected from the group consisting of the polymer classes of the polyamines, polyethyleneamines, polyanilines, polyimines, polyethyleneimines, polythiophenes, and polypryroles and also mixtures and copolymers thereof, with both the phosphating composition and the after-rinse composition being substantially nickel-free.

Provided herein is a method for specifically adjusting the electrical conductivity of a conversion coating, wherein a metallic surface or a conversion-coated metallic surface is treated with an aqueous composition which comprises at least one kind of metal ions selected from the group consisting of the ions of molybdenum, copper, silver, gold, palladium, tin, and antimony and/or at least one electrically conductive polymer selected from the group consisting of the polymer classes of the polyamines, polyanilines, polyimines, polythiophenes, and polypryrols.

An aqueous passivation composition, having a pH of less than 3, comprising: i) a source of trivalent chromium ions; ii) at least one -hydroxycarboxylic acid having general formula (I): R.sub.1CH(OH)COOH (I); wherein: R.sub.1 represents a hydrogen atom, a C1-C4 alkyl group, a C2-C6 alkenyl group, a C1-C6 alkoxy group, a C.sub.3-C.sub.6 cycloalkyl group or a C6-C10 aryl group; iii) phosphoric acid; iv) at least one water-soluble polyphosphonic acid or a water-soluble salt thereof, said polyphosphonic acid having general formula (II): Z[PO(OH).sub.2].sub.n (II); in which: n is at least 2; and Z is a connecting organic moiety having an effective valency of n, said polyphosphonic acid including at least two phosphonic groups separated by an alkylene bridge having 1 or 2 carbon atoms (C.sub.1-C.sub.2 alkylene); and v) at least one divalent metal cation;
wherein said composition is substantially free of: nitrate and fluoride anions, and hexavalent chromium.

The present invention relates to a method for treating a part (P) made of iron alloy for improving the anti-corrosion and mechanical strength properties thereof, the method comprising: a salt bath nitriding or salt bath nitrocarburising step, to form a combination layer (1) on the part (P), and subsequently a step of phosphating the part (P), to form a phosphating layer (2) on the surface of the part,
characterised in that the bath of molten salts contains chlorides, and the phosphating step is carried out in a phosphating bath which contains zinc ions and/or manganese ions, and iron ions.

Disclosed is a phosphate coating, comprising: a phosphate portion, wherein the phosphate portion comprises pores, wherein the pores are at least partially filled with a corrosion inhibition sealant, wherein the corrosion inhibition sealant comprises: a base, wherein the base comprises a matrix and a metal within the matrix, wherein the metal within the matrix comprises aluminum, an aluminum alloy, zinc, a zinc alloy, magnesium, a magnesium alloy, or a combination thereof and an inhibitor mixed within the base, wherein the inhibitor comprises zinc molybdate, magnesium metasilicate, trivalent chromium, tungstenate, a metal phosphate silicate, or a combination thereof.

Disclosed herein is a method of pre-treating a metallic substrate, the method including one or more cleaning steps, where at least part of the surface of the metallic substrate is contacted with one or more aqueous cleaning compositions, to obtain a cleaned metallic substrate; and/or one or more chemical pre-treatment steps selected from the group consisting of conversion treating steps, passivation treating steps and thin-layer forming steps, where at least part of the surface of a metallic substrate is contacted with one or more chemical pre-treatment compositions selected from the group consisting of conversion treatment compositions, passivation treatment compositions and thin-layer forming compositions to obtain a chemically pre-treated substrate. Also disclosed herein is a method of coating a metallic substrate, where the first step consists of the method of pre-treating a substrate, where after a last rinsing step one or more coating compositions are applied and cured.