The corrosion resistance of conversion-coated metal substrate surfaces is further enhanced by treating such surfaces with aqueous mixtures of preformed reaction products obtained by reacting catechol compounds, such as dopamine or a dopamine salt, and functionalized co-reactant compounds, such as a polyethyleneimine.

The present invention addresses the problem of providing, a metal surface treatment agent capable of exhibiting excellent corrosion resistance and excellent coating adhesion in painted metal materials; and a metal surface treatment method using the metal surface treatment agent. The problem is solved by a pretreatment agent that is used in a pretreatment of a chemical conversion treatment performed for forming a chemical conversion coating on/over a surface of a metal material, the pretreatment agent containing: a metal alkoxide (A) containing at least one metal element selected from zirconium, titanium, vanadium, and aluminum; and at least one sulfonic acid (B) selected from methanesulfonic acid, ethanesulfonic acid, hydroxymethanesulfonic acid, and hydroxyethanesulfonic acid. The problem is also solved by a chemical conversion treatment agent that contains a zirconium alkoxide (a) and a zirconium-containing ion supply source (b), and has a pH of 1.5 to 6.5.

The present invention addresses the problem of providing, a metal surface treatment agent capable of exhibiting excellent corrosion resistance and excellent coating adhesion in painted metal materials; and a metal surface treatment method using the metal surface treatment agent. The problem is solved by a pretreatment agent that is used in a pretreatment of a chemical conversion treatment performed for forming a chemical conversion coating on/over a surface of a metal material, the pretreatment agent containing: a metal alkoxide (A) containing at least one metal element selected from zirconium, titanium, vanadium, and aluminum; and at least one sulfonic acid (B) selected from methanesulfonic acid, ethanesulfonic acid, hydroxymethanesulfonic acid, and hydroxyethanesulfonic acid. The problem is also solved by a chemical conversion treatment agent that contains a zirconium alkoxide (a) and a zirconium-containing ion supply source (b), and has a pH of 1.5 to 6.5.

A process for surface activation or depassivation of an article, in particular an alloy, by immersion of the alloy in an aqueous acid solution. The surface activation methods of the present invention can be performed during a relatively short period of time and achieve reductions in production costs and provide environmental friendliness as compared to prior art processes. In a further embodiment, after surface activation, the article is immersed in a second liquid that prevents re-formation of a passivating oxide layer on the surface of the article. In a further embodiment the surface-activated alloys are subjected to surface engineering by a process that infuses carbon or nitrogen through the surface at a temperature sufficiently low to suppress precipitation of carbides or nitrides.

A process for surface activation or depassivation of an article, in particular an alloy, by immersion of the alloy in an aqueous acid solution. The surface activation methods of the present invention can be performed during a relatively short period of time and achieve reductions in production costs and provide environmental friendliness as compared to prior art processes. In a further embodiment, after surface activation, the article is immersed in a second liquid that prevents re-formation of a passivating oxide layer on the surface of the article. In a further embodiment the surface-activated alloys are subjected to surface engineering by a process that infuses carbon or nitrogen through the surface at a temperature sufficiently low to suppress precipitation of carbides or nitrides.

An aqueous, acidic, anti-corrosion conversion coating composition (in particular, an aqueous, acidic Group IV metal-containing anti-corrosion conversion coating composition) for metal substrates comprising as an additive a catechol compound and/or the reaction products of at least one catechol compound and at least one co-reactant compound having one or more functional groups reactive with the at least one catechol compound, desirably the reaction product of a catechol and an polyamine (e.g., a polyethyleneimine), that enhances the anti-corrosion effects of the conversion coating composition; methods of making and applying the conversion coating compositions and coated metal substrates. The catechol-containing conversion coating composition can be applied to metal substrate surfaces at temperatures as low as below 40? C. and with exposure times of 5 minutes or less. The catechol compound or reaction product thereof can become incorporated into the conversion coating formed on the metal substrate.

The tendency of a bare metal surface to oxidize (e.g., flash-rust) may be alleviated by contacting the bare metal surface with an aqueous mixture of at least one preformed reaction product obtained by reaction of at least one catechol compound, such as dopamine or a salt thereof, with at least one co-reactant compound functionalized with one or more functional groups reactive with the at least one catechol compound, such as (meth)acryl, primary amino, secondary amino, thiol and/or hydroxyl groups, with polyethyleneimine being an example of a suitable co-reactant compound. Such a rinsing procedure does not interfere with subsequent conversion coating of the metal surface.

The corrosion resistance of conversion-coated metal substrate surfaces is further enhanced by treating such surfaces with aqueous mixtures of preformed reaction products obtained by reacting catechol compounds, such as dopamine or a dopamine salt, and functionalized co-reactant compounds, such as a polyethyleneimine.

A method of processing a metal member having a passivation film on its surface is provided. The method includes a step of heating the metal member for a predetermined period at a temperature of 300 C. or higher.

A method of processing a metal member having a passivation film on its surface is provided. The method includes a step of heating the metal member for a predetermined period at a temperature of 300 C. or higher.