Non-chromated oxide coating for aluminum substrates

A process for forming an oxide film cobalt conversion coating on a metal substrate, said process comprising the steps of:

• (a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution comprising a soluble cobalt-III hexacarboxylate complex, the concentration of said cobalt-III hexacarboxylate complex being from about 0.01 mole per liter of said aqueous reaction solution up to the saturation limit of said cobalt-III hexacarboxylate complex;
• and
• (b) contacting said substrate with said aqueous reaction solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt conversion coating is formed.

A process for forming an oxide film cobalt conversion coating on a metal substrate, said process comprising the steps of:

• (a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution prepared by reacting a cobalt-II salt with a metal carboxylate having from 1 to 5 carbon atoms, wherein the concentration of said cobalt-II salt is from about 0.04 mole per liter of final solution up to about 0.15 mole per liter of final solution, and the concentration of metal carboxylate is from about 0.03 to 2.5 mole per liter of final solution;
• and
• (b) contacting said substrate with said aqueous reaction solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt conversion coating is formed.

A process for forming an oxide film cobalt conversion coating on a substrate, wherein said substrate is aluminum or aluminum alloy, said process comprising the steps of:

• (a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution comprising a soluble cobalt-III hexacoordinated complex, where said cobalt-III hexacoordinated complex is present in the form of Me.sub.m [Co(R).sub.6 ].sub.n, wherein Me is one or more selected from the group consisting of Na, Li, K, Ca, Zn, Mg and Mn, and wherein m is 2 or 3, n is 1 or 2, and R is a carboxylate having from 1 to 5 C atoms, the concentration of said cobalt-III hexacoordinated complex being from about 0.01 mole per liter of said aqueous reaction solution up to the saturation limit of said cobalt-III hexacoordinated complex;
• and
• (b) contacting said substrate with said aqueous reaction solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt conversion coating is formed.

A process for forming an oxide film cobalt conversion coating on a substrate, wherein said substrate is aluminum or aluminum alloy, said process comprising the steps of:

• (a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution prepared by reacting a cobalt-II salt with a metal carboxylate having from 1 to 5 carbon atoms, wherein the concentration of said cobalt-II salt is from about 0.04 mole per liter of final solution up to about 0.15 mole per liter of final solution, and the concentration of metal carboxylate is from about 0.03 to 2.5 mole per liter of final solution;
• and
• (b) contacting said substrate with said aqueous reaction solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt conversion coating is formed.

A chemical conversion coating solution for producing an oxide film cobalt conversion coating on a metal substrate, said solution comprising an aqueous reaction solution comprising a soluble cobalt-III hexacoordinated complex, wherein said cobalt-III hexacoordinated complex is present in the form of Me.sub.m ]Co(R).sub.6 ].sub.n, wherein Me is one or more selected from the group consisting of Na, Li, K, Ca, Zn, Mg and Mn, and wherein m is 2 or 3, n is 1 or 2, and R is a carboxylate having from 1 to 5 C atoms, the concentration of said cobalt-III hexacoordinated complex being from about 0.01 mole per liter of said aqueous reaction solution up to the saturation limit of said cobalt-III hexacoordinated complex.

A chemical conversion coating solution for producing an oxide film cobalt conversion coating on a metal substrate, said solution comprising:

• (a) an aqueous reaction solution comprising a soluble cobalt-III carboxylate complex, the concentration of said cobalt-III carboxylate complex being from about 0.01 mole per liter of said aqueous reaction solution up to the saturation limit of said cobalt-III carboxylate complex;
• (b) wherein said aqueous reaction solution is prepared by reacting a cobalt-II salt with a metal carboxylate salt having from 1 to 5 C atoms, wherein the concentration of said cobalt-II salt is from about 0.01 mole per liter of final solution up to the saturation limit of the cobalt-II salt employed, the concentration of said metal carboxylate salt is from about 0.03 to 2.5 mole per liter of final solution.

A chemical conversion coating solution for producing an oxide film cobalt conversion coating on a metal substrate, wherein said substrate is aluminum or aluminum alloy, said solution comprising an aqueous reaction solution comprising a soluble cobalt-III hexacoordinated complex, wherein said cobalt-III hexacoordinated complex is present in the form of Me.sub.m [Co(R).sub.6 ].sub.n, wherein Me is one or more selected from the group consisting of Na, Li, K, Ca, Zn, Mg and Mn, and wherein m is 2 or 3, n is 1 or 2, and R is a carboxylate having from 1 to 5 C atoms, the concentration of said cobalt-III hexacoordinated complex being from about 0.01 mole per liter of said aqueous reaction solution up to the saturation limit of said cobalt-III hexacoordinated complex.

A chemical conversion coating solution for producing an oxide film cobalt conversion coating on a metal substrate, wherein said substrate is aluminum or aluminum alloy, said solution comprising:

• (a) an aqueous reaction solution comprising a soluble cobalt-III hexacarboxylate complex, the concentration of said cobalt-III hexacarboxylate complex being from about 0.01 mole per liter of said aqueous reaction solution up to the saturation limit of said cobalt-III hexacarboxylate complex;
• (b) wherein said aqueous reaction solution is prepared by reacting a cobalt-II salt with a metal carboxylate salt having from 1 to 5 C atoms, wherein the concentration of said cobalt-II salt is from about 0.01 mole per liter of final solution up to the saturation limit of the cobalt-II salt employed, the concentration of said metal carboxylate salt is from about 0.03 to 2.5 mole per liter of final solution.

An oxide film coated article exhibiting corrosion resistance and paint adhesion properties, said article comprising:

• (a) a substrate, said substrate being aluminum or aluminum alloy;
• and
• (b) an oxide film cobalt conversion coating formed on said substrate, said oxide film cobalt conversion coating comprising aluminum oxide Al.sub.2 O.sub.3 as the largest volume percent, and one or more cobalt oxides from the group consisting of CoO, Co.sub.2 O.sub.3, and Co.sub.3 O.sub.4.

A process for forming an oxide film cobalt conversion coating exhibiting corrosion resistance and paint adhesion properties on a substrate, wherein said substrate is aluminum or aluminum alloy, said process comprising the steps of:

• (a) providing an oxide film forming cobalt conversion reaction solution comprising an aqueous reaction solution prepared by reacting cobalt acetate with a metal acetate selected from the group consisting of Mg, Ca, and Na acetate, wherein the concentration of said cobalt acetate is about 30 to 35 grams per liter of final solution and the concentration of said metal acetate is about 65 to 130 grams per liter of final solution;
• and
• (b) contacting said substrate with said solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt conversion coating is formed, thereby imparting corrosion resistance and paint adhesion properties to said substrate.

A process for forming an oxide film cobalt conversion coating exhibiting corrosion resistance and paint adhesion properties on a substrate, wherein said substrate is aluminum or aluminum alloy, said process comprising the steps of:

• (a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution prepared by reacting cobalt acetate with a metal acetate selected from the group consisting of magnesium, calcium, and sodium acetate and mixtures thereof, wherein the concentration of said cobalt acetate is about 30 to 35 grams per liter of final solution and the concentration of said metal acetate is about 65 to 130 grams per liter of final solution;
• and
• (b) contacting said substrate with said solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt conversion coating is formed, thereby imparting corrosion resistance and paint adhesion properties to said substrate.

A process for forming an oxide film cobalt conversion coating exhibiting corrosion resistance and paint adhesion properties on a substrate, wherein said substrate is aluminum or aluminum alloy, said process comprising the steps of:

• (a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution of a soluble cobalt-III hexacarboxylate complex, wherein said cobalt-III hexacarboxylate complex is present in the form of Me.sub.m [Co(R).sub.6 ].sub.n wherein Me is one or more selected from the group consisting of Na, Li, K, Ca, Zn, Mg and Mn, and wherein m is 2 or 3, n is 1 or 2, and R is a carboxylate having from 1 to 5 C atoms, and wherein said cobalt-III hexacarboxylate complex was made by reacting a cobalt-II carboxylate salt with a metal carboxylate such that the concentration of said cobalt-III hexacarboxylate complex is from about 0.1 mole per gallon of solution to the solubility limit of said cobalt-III hexacarboxylate complex;
• and
• (b) contacting said metal substrate with said solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt conversion coating is formed, thereby imparting corrosion resistance and paint adhesion properties to said substrate.

A process for forming an oxide film cobalt conversion coating exhibiting corrosion resistance and paint adhesion properties on a substrate, wherein said substrate is aluminum, aluminum alloy, magnesium, magnesium alloy, a Cd plated substrate, or a Zn--Ni plated substrate, said process comprising the steps of:

• (a) providing an oxide film forming cobalt conversion reaction solution comprising an aqueous reaction solution prepared by reacting a cobalt-II salt with a metal carboxylate salt, wherein the concentration of said cobalt-II salt is from about 0.1 moles per gallon of final solution to the solubility limit of the cobalt-II salt employed and the concentration of said metal carboxylate salt is from about 0.03 to 2.5 moles per gallon of final solution;
• and
• (b) contacting said substrate with said aqueous reaction solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt conversion coating is formed, thereby imparting corrosion resistance and paint adhesion properties to said substrate.