The metal connector or adaptor for hydraulic or oil dynamic application at high pressure, comprises electrolytic passivated zinc plating free from hexavalent chromium, the zinc plating comprising an external trivalent chromium passivation layer, said passivation layer having a distinctive unique coloration among high corrosion resistance processes.

A surface treatment method capable of imparting exceptional corrosion resistance and moisture resistance to an NB heat exchanger. The method includes subjecting an NB heat exchanger to a chemical conversion treatment to form a chemical conversion film on the surface thereof using a chemical conversion treatment agent that contains zirconium and/or titanium in a total amount of 5-5,000 ppm by weight, vanadium in an amount of 10-1,000 ppm by weight, and has a pH of 2-6; bringing the NB heat exchanger on whose surface the chemical conversion film is formed into contact with a hydrophilization agent containing a hydrophilic resin and a guanidine compound and/or a salt thereof; and baking the NB heat exchanger subjected to the contacting process, whereby a hydrophilic film is formed on the surface thereof.

Provided are stainless steel for a separator of a polymer electrolyte membrane fuel cell, which exhibits enhanced hydrophilicity and enhanced corrosion resistance, and a method of manufacturing the same. In the stainless steel for a separator of a polymer electrolyte membrane fuel cell, which exhibits enhanced hydrophilicity and enhanced corrosion resistance, according to an embodiment of the present invention, a ratio of Cr hydroxide/Cr oxide included in a passivation film of the stainless steel ranges from 0.5 to 1.7, and the passivation film has a contact angle (θ) of 70° or less. Thus, not only corrosion resistance may be enhanced by removing a non-conductive film formed on a surface of the stainless steel and forming a new conductive film thereon, but hydrophilicity may also be secured without additional surface treatment such as a separate coating or the like, and thus manufacturing costs may be reduced and productivity may be increased.

Provided is a low-cost cold rolled steel sheet for zirconium-based chemical conversion treatment that contains Si and Mn and has excellent zirconium-based chemical convertibility even when a relatively large amount of Si-based oxide and Si—Mn-based oxide exists on the steel sheet surface. A cold rolled steel sheet for zirconium-based chemical conversion treatment comprises a chemical composition containing, in mass %, C: 0.05% to 0.30%, Si: 0.01% to 1.4%, Mn: 0.14% to 3.2%, P: 0.10% or less, and S: 0.01% or less, with a balance consisting of Fe and inevitable impurities, wherein a Si/Mn mass ratio in steel is 0.10 to 0.7, and a surface coating ratio of steel sheet surface layer oxides having Si content of 10 mass % or more is 40% or less.

Provided is a low-cost cold rolled steel sheet for zirconium-based chemical conversion treatment that contains Si and Mn and has excellent zirconium-based chemical convertibility even when a relatively large amount of Si-based oxide and Si—Mn-based oxide exists on the steel sheet surface. A cold rolled steel sheet for zirconium-based chemical conversion treatment comprises a chemical composition containing, in mass %, C: 0.05% to 0.30%, Si: 0.01% to 1.4%, Mn: 0.14% to 3.2%, P: 0.10% or less, and S: 0.01% or less, with a balance consisting of Fe and inevitable impurities, wherein a Si/Mn mass ratio in steel is 0.10 to 0.7, and a surface coating ratio of steel sheet surface layer oxides having Si content of 10 mass % or more is 40% or less.

Anti-corrosion metal pretreatment compositions comprising a Group IVB metal, a Group IB metal and polyamidoamine polymers; replenisher compositions for the metal pretreatment compositions; methods of making the metal pretreatment compositions; methods of forming an anti-corrosion Group IVB oxide coating on at least one metal substrate surface by contacting the surface with the metal pretreatment composition; and coated metal substrates having anti-corrosion coatings deposited on the metal substrates from chrome VI free, anti-corrosion metal pretreatment compositions having enhanced corrosion resistance of the Group IVB metal oxide coatings and adhesion of the anti-corrosion and primer coating layers to metal substrates.

Anti-corrosion metal pretreatment compositions comprising a Group IVB metal, a Group IB metal and polyamidoamine polymers; replenisher compositions for the metal pretreatment compositions; methods of making the metal pretreatment compositions; methods of forming an anti-corrosion Group IVB oxide coating on at least one metal substrate surface by contacting the surface with the metal pretreatment composition; and coated metal substrates having anti-corrosion coatings deposited on the metal substrates from chrome VI free, anti-corrosion metal pretreatment compositions having enhanced corrosion resistance of the Group IVB metal oxide coatings and adhesion of the anti-corrosion and primer coating layers to metal substrates.

Provided are a novel chemical conversion treatment agent which is capable of forming, on/over the surface of a metal material, a chemical conversion coating which is superior in corrosion resistance, a method for producing a chemical conversion coating on/over the surface of a metal material with the use of the chemical conversion treatment agent, a metal material having a coating, and a painted metal material. The problem mentioned above can be solved by the chemical conversion treatment agent for forming a coating on/over the surface of a metal material, which characterized by containing: an ion containging at least one metal selected from the group consisting of titanium, zirconium and hafnium; a fluorine ion; at least one selected from the group consisting of an alkanesulfonic acid, an alkanolsulfonic acid, and ions thereof; and an ion containing trivalent iron.

Provided are a novel chemical conversion treatment agent which is capable of forming, on/over the surface of a metal material, a chemical conversion coating which is superior in corrosion resistance, a method for producing a chemical conversion coating on/over the surface of a metal material with the use of the chemical conversion treatment agent, a metal material having a coating, and a painted metal material. The problem mentioned above can be solved by the chemical conversion treatment agent for forming a coating on/over the surface of a metal material, which characterized by containing: an ion containging at least one metal selected from the group consisting of titanium, zirconium and hafnium; a fluorine ion; at least one selected from the group consisting of an alkanesulfonic acid, an alkanolsulfonic acid, and ions thereof; and an ion containing trivalent iron.

The present invention relates to an acidic aqueous composition for coating metallic surfaces, particularly of aluminium materials, that comprises, besides water and optionally further components, a) at least one compound selected from the group consisting of organoalkoxysilanes, organosilanols, polyorganosilanols, organosiloxanes and polyorganosiloxanes, b) at least one compound selected from the group consisting of titanium, zirconium, hafnium and aluminium compounds and silicon complex fluoride, and c) at least one copolymer which is stable at least in a segment of the pH range below 6 and which comprises, in alternating configuration, monomer units containing at least one carboxylic and/or phosphonic acid group and monomer units containing no acid group. The invention further relates to a corresponding coating method and to the use of the substrates coated by this method.