A method of inhibiting corrosion of duplex stainless steel by aqueous acidic solution, comprises carrying out a preliminary treatment which is passivation of the steel while exposing the steel to a first aqueous acidic solution containing at least one organic corrosion inhibitor able to adsorb to a steel surface, so as to deposit a passivating and corrosion inhibiting film on the steel surface; and thereafter during a second period of time exposing the steel to a second aqueous acidic solution different from the first aqueous acidic solution and also containing at least one organic corrosion inhibitor able to adsorb to a steel. The second aqueous acidic solution maintains the film on the steel surface, such that weight loss through corrosion in the second period of time is lower than the weight loss which would be observed with the same second aqueous acidic solution but without carrying out the preliminary treatment.

The invention relates to a method for producing a silane-modified silicate. In order to obtain optimal corrosion protection properties, a silane compound according to the invention is at least partially hydrolyzed and/or condensed in the presence of a silicate compound at a pH value greater than or equal to 8 and then a pH value less than or equal to 7 is set by adding acid. The invention further relates to an aqueous acidic passivation composition for metal substrate coated with the passivation composition.

The invention relates to a method for producing a silane-modified silicate. In order to obtain optimal corrosion protection properties, a silane compound according to the invention is at least partially hydrolyzed and/or condensed in the presence of a silicate compound at a pH value greater than or equal to 8 and then a pH value less than or equal to 7 is set by adding acid. The invention further relates to an aqueous acidic passivation composition for metal substrate coated with the passivation composition.

A non-phosphorus chemical conversion treatment agent and treatment liquid for plastic working are provided, with reduced environmental impact, which are able to form films that are excellent in lubricity and corrosion resistance after plastic working by achieving large film thicknesses even in a system containing a salt of molybdic acid as its main constituent. An exemplary non-phosphorus chemical conversion treatment agent for plastic working is an agent containing a molybdic acid component (A), an acid component (B), and an aqueous medium (C), which is characterized in that the (B) comprises at least an organic acid component (B1) having at least one group selected from a carboxyl group and a phenolic hydroxyl group.

A non-phosphorus chemical conversion treatment agent and treatment liquid for plastic working are provided, with reduced environmental impact, which are able to form films that are excellent in lubricity and corrosion resistance after plastic working by achieving large film thicknesses even in a system containing a salt of molybdic acid as its main constituent. An exemplary non-phosphorus chemical conversion treatment agent for plastic working is an agent containing a molybdic acid component (A), an acid component (B), and an aqueous medium (C), which is characterized in that the (B) comprises at least an organic acid component (B1) having at least one group selected from a carboxyl group and a phenolic hydroxyl group.

A method of selecting a corrosion-inhibiting substance includes selecting a corrosion-inhibiting substance to include a non-tungstate anodic corrosion inhibitor with respect to an amount of zinc in an aluminum alloy substrate that is to be coated with the corrosion-inhibiting substance.

A method of selecting a corrosion-inhibiting substance includes selecting a corrosion-inhibiting substance to include a non-tungstate anodic corrosion inhibitor with respect to an amount of zinc in an aluminum alloy substrate that is to be coated with the corrosion-inhibiting substance.

The invention relates to a method for producing a silane-modified silicate. In order to obtain optimal corrosion protection properties, a silane compound according to the invention is at least partially hydrolyzed and/or condensed in the presence of a silicate compound at a pH value greater than or equal to 8 and then a pH value less than or equal to 7 is set by adding acid. The invention further relates to an aqueous acidic passivation composition for metal substrate coated with the passivation composition.

The invention relates to a method for producing a silane-modified silicate. In order to obtain optimal corrosion protection properties, a silane compound according to the invention is at least partially hydrolyzed and/or condensed in the presence of a silicate compound at a pH value greater than or equal to 8 and then a pH value less than or equal to 7 is set by adding acid. The invention further relates to an aqueous acidic passivation composition for metal substrate coated with the passivation composition.

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.