WO2017063513A1 - Passivation not involving chromium, phosphorus and fluoride, and organic film coating - Google Patents

Abstract

A coating composition capable of being used for passivating a metal surface. The coating composition contains water, aminosilane, epoxy silane, transition metal compounds and polymer resin, and the coating does not contain chromium, phosphorus and fluoride.

Description

Passivation and organic film coatings free of chromium, phosphorus and fluoride

background

Thin film organic passivation is used industrially to provide corrosion protection to metals. Conventional formulations include chromium; although these formulations may have excellent passivating properties, they may also have the disadvantage of poor paint adhesion and deleterious environmental effects. Other conventional ingredients, such as fluoride and phosphorus, can be used in place of chromium, but may also have negative environmental and/or ecological effects. This invention relates to novel formulations of passivation and thin organic film coatings that are free of chromium, fluoride-free and phosphorus-free, which provide good corrosion protection and improved coating adhesion on the surface of metallic materials.

Summary of invention

According to some embodiments, the present invention relates to a coating composition useful for passivating a metal surface comprising: water and: an aminosilane; an epoxy silane; a transition metal compound; and a polymeric resin, wherein the coating contains no chromium, no fluorine And does not contain phosphorus. In some embodiments, the aminosilane is present in an amount from about 0.5% to about 5% by weight of the coating composition; the epoxy silane is present in an amount from about 2% to about 25% by weight of the coating composition; The metal compound is present in an amount from about 0.05% to about 5% by weight of the coating composition; and/or the polymeric resin is present in an amount from about 1% to about 30% by weight of the coating composition.

In some embodiments, the coating composition further comprises ethyl orthosilicate. In some embodiments, the transition metal comprises Zr(NO ₃ ) ₄ , Ce(NO ₃ ) ₃ , TiO(NO ₃ ) ₂ , (NH ₄ ) ₂ Ce(NO ₃ ) ₆ and/or Mn(NO ₃ ) ₂ .

In certain embodiments, the coating composition provides corrosion resistance to the metal surface when applied at a film thickness of less than about 2 [mu]m, or when applied at a film thickness of less than about 1.2 [mu]m. In some embodiments, the coating composition provides corrosion resistance to the metal surface when applied at a peak metal temperature of from about 40 °C to about 150 °C.

According to some embodiments, a method of passivating a metal surface comprises coating a metal surface with a coating composition comprising water and: an aminosilane; an epoxy silane; a transition metal compound; and a polymeric resin, wherein the coating is not Contains chromium, no fluoride and no phosphorus.

Detailed description of the invention

The compositions and methods of the present invention relate to passivation and organic film coatings that are chrome-free, fluoride-free, and phosphorus-free. The unique combination of components allows the coating of the present invention to provide corrosion protection and improved coating adhesion on the surface of the metallic material while being environmentally and eco-friendly. Moreover, coatings of some embodiments of the present invention can be applied at lower peak metal surface temperatures and/or smaller film thicknesses than current techniques, while also providing a desired level of corrosion protection and coating adhesion. Peak metal temperature or PMT is understood to mean the average maximum temperature obtained by the metal substrate during the drying/curing process in the coating line.

In some embodiments, the coating compositions of the present invention can include one or more of the following: aminosilanes, epoxysilanes, transition metal compounds, and/or polymeric resins. The coating composition and individual components are described in more detail below.

Aminosilane

In some embodiments, the coating compositions of the present invention comprise one or more aminosilanes. Suitable aminosilanes can include, for example, monoaminosilanes, bisaminosilanes, and/or aminofunctional oligomeric silanes. In some embodiments, suitable aminosilanes include 3-(trimethoxysilyl)propylamine and/or its oligomers, bifunctionals with reactive primary amines and hydrolyzable inorganic methoxysilyl groups. Organosilane, for example

Diamino-functional oligosiloxanes such as

2776 (copolycondensate of diaminoalkoxysilane and methylalkoxysilane), and/or difunctional silane having reactive primary amino group and hydrolyzable ethoxysilyl group, for example

In some embodiments, the coating composition includes one or more aminosilanes in an amount from about 0.1% to about 20% by weight of the coating composition; from about 0.1% to about 15% of the coating composition. % by weight; from about 0.1% by weight to about 10% by weight of the coating composition; from about 0.2% by weight to about 8% by weight of the coating composition; from about 0.3% by weight to about 7% by weight of the coating composition From about 0.4% to about 6% by weight of the coating composition; from about 0.5% to about 5% by weight of the coating composition; about 0.1% by weight of the coating composition; of the coating composition About 0.2% by weight; about 0.3% by weight of the coating composition; about 0.4% by weight of the coating composition; about 0.5% by weight of the coating composition; about 0.6% by weight of the coating composition; About 0.7% by weight of the coating composition; about 0.8% by weight of the coating composition; about 0.9% by weight of the coating composition; about 1% by weight of the coating composition; about about the coating composition 2% by weight; about 3% by weight of the coating composition; the coating combination About 4% by weight; about 5% by weight of the coating composition; about 6% by weight of the coating composition; about 7% by weight of the coating composition; about 8% by weight of the coating composition; About 9% by weight of the coating composition; about 10% by weight of the coating composition; about 12% by weight of the coating composition; about 15% by weight of the coating composition; About 17% by weight; or about 20% by weight of the coating composition.

Epoxy silane

In some embodiments, the coating compositions of the present invention comprise one or more epoxy silanes. Suitable epoxy silanes can include, for example, methoxysilyl, ethoxysilyl, and/or epoxy functional oligomeric silanes. In some embodiments, suitable epoxy silanes include 3-(2,3-epoxypropoxy)propyl]trimethoxysilane and/or oligomers thereof, having reactive organic epoxides and Hydrolyzed inorganic methoxysilyl difunctional organosilane, for example

An organosilicon compound based on water as a solvent, for example

2926 (product of ethoxyalkoxysilane), and/or difunctional organosilane having a reactive organic epoxide and a hydrolyzable inorganic triethoxysilyl group, for example

In some embodiments, the coating composition includes one or more epoxy silanes in an amount from about 0.1% to about 50% by weight of the coating composition; from about 0.2% to about 5% by weight of the coating composition 45 wt%; from about 0.5% to about 40% by weight of the coating composition; from about 0.5% to about 35% by weight of the coating composition; from about 1% to about 30% by weight of the coating composition %; from about 2% by weight to about 25% by weight of the coating composition; about 0.1% by weight of the coating composition; about 0.2% by weight of the coating composition; about 0.5% by weight of the coating composition About 1% by weight of the coating composition; about 2% by weight of the coating composition; about 5% by weight of the coating composition; about 7% by weight of the coating composition; the coating composition About 10% by weight; about 12% by weight of the coating composition; about 15% by weight of the coating composition; about 20% by weight of the coating composition; about 25% by weight of the coating composition; About 30% by weight of the coating composition; about 35% by weight of the coating composition; From about 40 wt% of said coating composition; about 45% by weight of said coating composition; or from about 50 wt% of said coating composition.

Metal compound

In some embodiments, the coating compositions of the present invention comprise one or more metal compounds. Suitable metals include Zr, Ti, Ce, Mn, etc., their related salts and compounds, and combinations thereof. In some embodiments, suitable examples include Zr(NO ₃ ) ₄ , Ce(NO ₃ ) ₃ , TiO(NO ₃ ) ₂ , (NH ₄ ) ₂ Ce(NO ₃ ) ₆ and/or Mn(NO ₃ ) ₂ .

In some embodiments, the coating composition includes one or more transition metal compounds in an amount from about 0.01% to about 20% by weight of the coating composition; from about 0.01% to about about 5% by weight of the coating composition 15% by weight; from about 0.01% to about 10% by weight of the coating composition; from about 0.02% to about 8% by weight of the coating composition; from about 0.03% to about 7% by weight of the coating composition %; from about 0.04% by weight to about 6% by weight of the coating composition; from about 0.05% by weight to about 5% by weight of the coating composition; about 0.01% by weight of the coating composition; the coating composition About 0.02% by weight; about 0.03% by weight of the coating composition; about 0.04% by weight of the coating composition; about 0.05% by weight of the coating composition; about 0.06% by weight of the coating composition; About 0.07% by weight of the coating composition; about 0.1% by weight of the coating composition; about 0.2% by weight of the coating composition; about 0.3% by weight of the coating composition; About 0.5% by weight; about 0.5 weight of the coating composition % by weight; about 0.6% by weight of the coating composition; about 0.7% by weight of the coating composition; about 0.8% by weight of the coating composition; about 0.9% by weight of the coating composition; About 1% by weight of the composition; about 2% by weight of the coating composition; about 3% by weight of the coating composition; about 4% by weight of the coating composition; about 5 parts by weight of the coating composition %; about 6% by weight of the coating composition; about 7% by weight of the coating composition; about 8% by weight of the coating composition; about 9% by weight of the coating composition; About 10% by weight of the coating; about 12% by weight of the coating composition; about 15% by weight of the coating composition; about 17% by weight of the coating composition; or about 20% by weight of the coating composition %.

Polymer resin

In some embodiments, the coating compositions of the present invention comprise one or more polymeric resins. Suitable polymeric resins can include, for example, acrylics, polyurethane resins, epoxies, novolac resins, and/or combinations thereof. In some embodiments, suitable examples include solventless aliphatic cationic polycarbonate-polyurethane dispersions, for example

4835VP, aqueous solvent-free self-crosslinking acrylic dispersion such as

2447VP, and / or DSM sivo 1217.

In some embodiments, the coating composition includes one or more polymeric resins in an amount from about 0.1% to about 50% by weight of the coating composition; from about 0.2% to about 45% of the coating composition. % by weight; from about 0.5% to about 40% by weight of the coating composition; from about 0.5% to about 35% by weight of the coating composition; from about 1% to about 30% by weight of the coating composition From about 2% by weight to about 25% by weight of the coating composition; about 0.1% by weight of the coating composition; about 0.2% by weight of the coating composition; about 0.5% by weight of the coating composition; About 1% by weight of the coating composition; about 2% by weight of the coating composition; about 5% by weight of the coating composition; about 7% by weight of the coating composition; About 10% by weight; about 12% by weight of the coating composition; about 15% by weight of the coating composition; about 20% by weight of the coating composition; about 25% by weight of the coating composition; About 30% by weight of the coating composition; about 35% by weight of the coating composition; From about 40 wt% of said coating composition; about 45% by weight of said coating composition; or from about 50 wt% of said coating composition.

Other components

In some embodiments, the coating composition of the present invention comprises water in an amount from about 15% to about 98% by weight of the coating composition; from about 20% to about 97% by weight of the coating composition; From about 25% by weight to about 97% by weight of the coating composition; from about 30% by weight to about 97% by weight of the coating composition; from about 35% by weight to about 96.5% by weight of the coating composition; From about 40% by weight to about 95% by weight of the coating composition; from about 45% by weight to about 95% by weight of the coating composition; from about 50% by weight to about 90% by weight of the coating composition; From about 55% by weight to about 85% by weight of the coating; from about 60% by weight to about 80% by weight of the coating composition; from about 65% by weight to about 75% by weight of the coating composition; of the coating composition About 15% by weight; about 20% by weight of the coating composition; about 25% by weight of the coating composition; about 30% by weight of the coating composition; about 35% by weight of the coating composition; About 40% by weight of the coating composition; about 45% by weight of the coating composition; the coating combination About 50% by weight; about 555% by weight of the coating composition; about 60% by weight of the coating composition; about 65% by weight of the coating composition; about 70% by weight of the coating composition; About 75% by weight of the coating composition; about 80% by weight of the coating composition; about 85% by weight of the coating composition; about 90% by weight of the coating composition; About 95% by weight; or about 98% by weight of the coating composition.

In some embodiments, the coating compositions of the present invention comprise a non-functional silane. Examples of suitable non-functional silanes include, but are not limited to, tetraethyl orthosilicate ("TEOS"). In some embodiments, the coating composition comprises a non-functional silane in an amount from about 0.5% to about 10% by weight of the coating composition; from about 1% to about 9% by weight of the coating composition; 2% by weight to about 8% by weight; or from about 3% by weight to about 7% by weight of the coating composition.

In some embodiments, the coating compositions of the present invention include any suitable additive, such as, but not limited to, a wax, in an amount suitable to achieve the desired effect in the coating composition.

use

The coatings of the present invention provide corrosion protection and improved coating adhesion on the surface of metallic materials, while the coatings are environmentally and eco-friendly due to the fact that they are chromium free, fluoride free and phosphorus free. Moreover, coatings of some embodiments of the present invention can be applied at lower peak metal surface temperatures and/or lower film thicknesses than current technologies, while also providing a desired level of corrosion protection and coating adhesion.

The coating composition of the present invention is particularly useful on the surface of zinc and/or zinc alloys such as galvanized sheets, galvanized sheets, hot-dip galvanized sheets, aluminum and aluminum alloys. In some embodiments, the rolls of sheets or their components are coated by conventional coating methods such as spraying and extrusion, roll coating, and the like. In some embodiments, the coating can occur at any suitable temperature, including room temperature and elevated temperatures. In some embodiments, subsequent curing or crosslinking of the solution can occur at a peak metal temperature, such as from about 40 °C to about 150 °C, or from about 50 °C to about 150 °C.

In some embodiments, the coating composition is formulated to provide superior corrosion protection as compared to current chromium-free passivation products at the same peak metal surface temperature (PMT) and film thickness conditions.

In some embodiments, the coating provides corrosion resistance (according to ASTM B117) of greater than about 24 hours on the galvanized steel at a PMT of about 40 ° C and a film thickness of 1.0 +/- 0.2 μm; greater than about 48 hours; greater than About 60 hours; greater than about 70 hours; greater than about 72 hours; greater than about 80 hours; greater than about 90 hours; greater than about 96 hours; greater than about 100 hours; greater than about 110 hours; greater than about 120 hours; greater than about 130 hours; greater than About 140 hours; about 100 hours to about 200 hours; about 110 hours to about 190 hours; about 120 hours to about 180 hours; about 130 hours to about 170 hours; or about 140 hours to about 160 hours.

In some embodiments, the coating provides corrosion resistance (according to ASTM B117) of greater than about 96 hours on the galvanized steel at a PMT of about 80 ° C and a film thickness of 1.0 +/- 0.2 μιη; greater than about 120 hours; greater than About 140 hours; greater than about 160 hours; greater than about 180 hours; greater than about 200 hours; greater than about 220 hours; greater than about 230 hours; from about 200 hours to about 280 hours; from about 220 hours to about 260 hours; or about 230 hours. About 250 hours.

In some embodiments, the coating provides corrosion resistance (according to ASTM B117) of greater than about 24 hours on the galvanized steel at a PMT of about 40 ° C and a film thickness of 0.5 +/- 0.2 μιη; greater than about 40 hours; greater than About 48 hours; greater than about 50 hours; greater than about 60 hours; greater than about 70 hours; about 40 hours to about 100 hours; about 50 hours to about 90 hours; or about 60 hours to about 80 hours.

In some embodiments, the coating provides corrosion resistance (according to ASTM B117) of greater than about 48 hours on the galvanized steel at a PMT of about 80 ° C and a film thickness of 0.5 +/- 0.2 μιη; greater than about 50 hours; greater than About 60 hours; greater than about 70 hours; greater than about 80 hours; greater than about 90 hours; greater than about 96 hours; greater than about 110 hours; greater than about 120 hours; greater than about 130 hours; greater than about 140 hours; about 100 hours to about 200 Hour; about 110 hours to about 190 hours; about 120 hours to about 180 hours; about 130 hours to about 170 hours; or about 140 hours to about 160 hours.

In some embodiments, the coating compositions of the present invention provide corrosion resistance over a much wider range of curing temperatures than existing chromium-free passivated products. For example, when applied by a bar coater (selected from RDS No. 2-4) at a fixed concentration, the coating compositions of some embodiments of the present invention provide corrosion resistance when the PMT is from about 40 ° C to about 150 ° C. Properties, while existing chromium-free passivation products range from about 60 ° C to about 150 ° C. In some embodiments, at about 40 ° C to about 150 ° C; from about 40 ° C to about 130 ° C; from about 40 ° C to about 110 ° C; from about 40 ° C to about 100 ° C; from about 40 ° C to about 80 ° C; about 40 ° C - about 70 ° C; about 40 ° C to about 60 ° C; about 40 ° C to about 55 ° C; about 45 ° C to about 55 ° C; about 45 ° C to about 60 ° C; about 45 ° C to about 50 ° C; about 45 ° C - about The coating composition of the present invention provides corrosion resistance at a PMT of 54 ° C; or from about 40 ° C to about 54 ° C. The ability to provide corrosion resistance at lower PMT ranges, for example from about 40 ° C to about 60 ° C, may be advantageous because, for example, lower operating temperatures require less energy consumption, and because these PMTs are commonly used.

In some embodiments, the coating compositions of the present invention can provide corrosion resistance at a film thickness of about 2 μm or less; about 1.5 μm or less; about 1.2 μm or less; about 1 μm or less; 0.9 μm or less; about 0.8 μm or less; about 0.7 μm or less; about 0.6 μm or less; about 0.5 μm or less; about 0.4 μm or less; about 0.3 μm or less; about 0.2 Mm or less; about 2 μm; about 1.5 μm; about 1.2 μm; about 1 μm; about 0.9 μm; about 0.8 μm; about 0.7 μm; about 0.6 μm; about 0.5 μm; about 0.4 μm; about 0.3 μm; about 0.2 μm About 0.1 μm to about 2 μm; about 0.1 μm to about 1.5 μm; about 0.1 μm to about 1 μm; about 0.2 μm to about 1 μm; about 0.1 μm to about 0.9 μm; about 0.2 μm to about 0.9 μm; about 0.1 μm- About 0.8 μm; from about 0.2 μm to about 0.8 μm; from about 0.1 μm to about 0.7 μm; from about 0.2 μm to about 0.7 μm; from about 0.1 μm to about 0.6 μm; from about 0.2 μm to about 0.6 μm; from about 0.1 μm to about 0.5 Mm; from about 0.2 μm to about 0.5 μm; from about 0.1 μm to about 0.4 μm; from about 0.2 μm to about 0.4 μm; from about 0.1 μm to about 0.3 μm; or from about 0.2 μm to about 0.3 μm, or from about 0.5 μm to about 2.0 Mm.

In some embodiments, the coating compositions of the present invention can be tested by passivation properties even at low film thicknesses, such as 0.5 [mu]m +/- 0.2 [mu]m or less. These tests may include neutral salt spray tests according to ASTM B-117, anti-solvent, high temperature resistance, alkali resistance and humidity tests, and the like. For example, in some embodiments, when the coating composition is applied to the panel with a passivation layer of 0.5 +/- 0.2 μm and tested according to the neutral salt spray test ASTM B-117, after 72 hours, the panel Can display no rust. In some embodiments, when the coating is applied to a panel and the film adhesion is tested according to ASTM D3359-02, the panel exhibits no coating loss after 100 cells.

As used throughout, the term "about" is understood to mean ± 10% of the recited value. For example, "about 100" should be understood to mean literally 90-110.

Example

Example 1

A coating composition was prepared according to the following formulation:

Component	Quantity (wt%)
Aminosilane	0.5-5
Epoxy silane	2-25
Metal (Zr or Ti or Ce) compound	0.05-5
Resin (acrylic or polyurethane or other)	1-30
water	35-96.5

Example 2

A coating composition was prepared in accordance with an embodiment of the present invention and evaluated for corrosion resistance and coating properties in comparison with a comparative coating.

Comparative preparations were prepared according to the following:

Component	Quantity (wt%)
water	67.5
Epoxy silane (GLYMO)	4
Aminosilane (AMMO)	2
Non-functional silane (TEOS)	4
H 2 TiF 6	0.5
H 3 PO 4	2
Acrylic resin	10
Polyurethane resin	10

Coating according to an embodiment of the invention:

Component	Quantity (wt%)
water	71.5
Aminosilane (AMMO)	1
Epoxy silane (GLYMO)	6
Zr(NO 3 ) 4	1.5
Acrylic resin	10
Polyurethane resin	10

Corrosion resistance was evaluated on galvanized steel substrates by ASTM B117, which is hereby incorporated by reference in its entirety.

Coating properties were evaluated on galvanized steel substrates by ASTM D 3359-02, which is incorporated herein by reference in its entirety.

The test conditions and results are as follows:

The coatings were tested at 40 ° C and 80 ° C peak metal surface temperature (PMT) and at coating thicknesses of 0.5 +/- 0.2 μm and 1.0 +/- 0.2 μm. As shown in the above table, the inventive coatings provided comparable or superior corrosion resistance to the comparative coatings under each of the test conditions.

The results show that the inventive coatings performed equally well with the comparative coatings under all test conditions and were superior to the desired results of 4B. According to ASTM D3359-02, 5B is the best result that can be achieved.

Example 3

A coating is prepared in accordance with an embodiment of the present invention.

Component	Quantity (wt%)
water	71.5
Aminosilane (AMMO)	1
Epoxy silane (GLYMO)	6
Ce(NO 3 ) 3	1.5
Acrylic resin	10
Polyurethane resin	10

On an galvanized sheet substrate (55% aluminum-zinc alloy coated steel sheet), the inventive coating composition passed an 8-week humidity test at a PMT of 80 ° C and a coating thickness of approximately 1.5 +/- 0.3 μm. 400 hour neutral salt spray test (ASTM B117).

Example 4

The inventive coatings were prepared and tested for resistance to solvents, high temperatures, alkali and humidity.

Test preparation

Component	Quantity (wt%)
water	71.5
Aminosilane (AMMO)	1

Epoxy silane (GLYMO)	6
Zr(NO 3 ) 4	1.5
Acrylic	10
Polyurethane resin	10

The above formulations were tested as described in the table below. It was shown that the test was repeated on two identical panels (panel 1 and panel 2) of hot dip galvanized steel coated with the prepared formulation. The test was carried out at a film thickness of from about 0.5 [mu]m to about 0.8 [mu]m.

ΔE represents the color difference before and after the coating panel test. by

The machine measures the color. NSS stands for Neutral Salt Spray Test according to ASTM B-117. Parker FC-364S is an alkaline cleaner.

The above test results demonstrate the effectiveness of the formulation in providing the desired level of corrosion protection and coating adhesion.

While the illustrative embodiments of the invention are disclosed herein, it is understood that many modifications and other embodiments can be devised by those skilled in the art. For example, features of different embodiments may be used in other embodiments. Therefore, it is to be understood that the appended claims are intended to cover all such modifications and embodiments

Claims (20)

1. A coating composition that can be used to passivate a metal surface comprising water and:

   (a) an aminosilane;

   (b) an epoxy silane;

   (c) a transition metal compound; and

   (d) a polymeric resin,

   Wherein the coating is free of chromium, fluoride free and free of phosphorus.
2. The coating composition of claim 1 wherein said amino silane is present in an amount from about 0.5% to about 5% by weight of said coating composition.
3. The coating composition of claim 1 wherein said epoxy silane is present in an amount from about 2% to about 25% by weight of said coating composition.
4. The coating composition of claim 1 wherein said transition metal compound is present in an amount from about 0.05% to about 5% by weight of said coating composition.
5. The coating composition of claim 1 wherein said polymeric resin is present in an amount from about 1% to about 30% by weight of said coating composition.
6. The coating composition of claim 1 further comprising ethyl orthosilicate.
7. The coating composition of claim 1 wherein said transition metal comprises Zr(NO ₃ ) ₄ , Ce(NO ₃ ) ₃ , TiO(NO ₃ ) ₂ , (NH ₄ ) ₂ Ce(NO ₃ ) ₆ and/or Mn (NO ₃ ) ₂ .
8. The coating composition of claim 1 wherein said coating composition provides corrosion resistance to the metal surface when applied at a film thickness of less than about 2 μm.
9. The coating composition of claim 1 wherein said coating composition provides corrosion resistance to the metal surface when applied at a film thickness of less than about 1.2 μm.
10. The coating composition of claim 1 wherein said coating composition provides corrosion resistance to the metal surface when applied at a peak metal temperature of from about 40 °C to about 150 °C.
11. A method of passivating a metal surface comprising coating the metal surface with a coating composition comprising water and:

    (a) an aminosilane;

    (b) an epoxy silane;

    (c) a transition metal compound; and

    (d) a polymeric resin,

    Wherein the coating is free of chromium, fluoride free and free of phosphorus.
12. The method of claim 11 wherein said amino silane is present in an amount from about 0.5% to about 5% by weight of said coating composition.
13. The method of claim 11 wherein said epoxy silane is present in an amount from about 2% to about 25% by weight of said coating composition.
14. The method of claim 11 wherein said transition metal compound is present in an amount from about 0.05% to about 5% by weight of said coating composition.
15. The method of claim 11 wherein said polymeric resin is present in an amount from about 1% to about 30% by weight of said coating composition.
16. The method of claim 11 wherein said coating composition further comprises ethyl orthosilicate.
17. The method of claim 11 wherein said transition metal comprises Zr(NO ₃ ) ₄ , Ce(NO ₃ ) ₃ , TiO(NO ₃ ) ₂ , (NH ₄ ) ₂ Ce(NO ₃ ) ₆ and/or Mn (NO) ₃ ) ₂ .
18. The method of claim 11 wherein said coating composition is applied to the metal surface at a thickness of less than about 2 μm.
19. The method of claim 11 wherein said coating composition is applied to the metal surface at a thickness of less than about 1.2 μm.
20. The method of claim 11 wherein said coating composition is applied to said metal surface at a peak metal temperature of from about 40 °C to about 150 °C.