US-20260124642-A1 - SYSTEMS AND METHODS FOR TREATING A SUBSTRATE

Abstract

Disclosed herein are systems and methods for treating a metal substrate. The system includes a first pretreatment composition comprising a fluorometallic acid and free fluoride and having a pH of 1.0 to 4.0 and a second pretreatment composition comprising a Group IVB metal or a third pretreatment comprising a lanthanide series metal and an oxidizing agent. The method includes contacting at least a portion of a surface of the substrate with the first pretreatment composition and optionally contacting at least a portion of the substrate surface with the second pretreatment composition or the third pretreatment composition. Also disclosed are substrates treated with one of the systems or methods. Also disclosed are magnesium or magnesium alloy substrates comprising a bilayer comprising a first layer comprising silicon and a second layer comprising fluoride.

Inventors

• Rachel D. Harris
• Kristi M. Allen
• Elizabeth S. Brown-Tseng
• Justin J. Martin
• Kuldeep KUMAR
• Mark W. McMillen
• SILVIA BEZER

Assignees

• PPG INDUSTRIES OHIO, INC.

Dates

Publication Date

20260507

Application Date

20250527

Claims (19)

1. 1 . A method of treating a metal substrate comprising: contacting a surface of the substrate with a first pretreatment composition comprising a fluorometallic acid comprising a Group IVA metal and/or a Group IVB metal and free fluoride in an amount of 10 ppm to 500 ppm based on total weight of the first pretreatment composition and having a pH of 1.0 to 4.0; and contacting the substrate surface with a second pretreatment composition comprising a Group IVB metal and free fluoride in an amount of 15 ppm to 200 ppm based on total weight of the second pretreatment composition; or contacting the substrate surface with a third pretreatment composition comprising a lanthanide series metal and an oxidizing agent.
2. 2 . The method of claim 1 , wherein the first pretreatment composition comprises the Group IVA metal in an amount of 10 ppm to 1,500 ppm and/or the Group IVB metal in an amount of 200 ppm to 5,000 ppm, wherein the amounts are based on total weight of the first pretreatment composition.
3. 3 . The method of claim 1 , wherein the second pretreatment composition comprises the Group IVB metal in an amount of 20 ppm to 1,000 ppm based on total weight of the second pretreatment composition.
4. 4 . The method of claim 1 , wherein the second pretreatment has a pH of 2 to 6.5.
5. 5 . The method of claim 1 , wherein the second pretreatment further comprises an electropositive metal, a Group IA metal, a Group IVB metal, and/or a Group VIIIB metal.
6. 6 . The method of claim 5 , wherein the second pretreatment comprises: the electropositive metal in an amount of 2 ppm to 100 ppm; the Group IA metal in an amount of 2 ppm to 500 ppm; the Group IVB metal in an amount of 5 ppm to 500 ppm; and/or the Group VIIIB metal in an amount of 0.1 ppm to 50 ppm, wherein the amounts are based on total weight of the second pretreatment composition.
7. 7 . The method of claim 1 , wherein the third pretreatment composition comprises the lanthanide series metal in an amount of 5 ppm to 25,000 ppm based on total weight of the third pretreatment composition.
8. 8 . The method of claim 1 , wherein the third pretreatment composition comprises the oxidizing agent in an amount of 25 ppm to 13,000 ppm based on total weight of the third pretreatment composition.
9. 9 . The method of claim 1 , wherein the third pretreatment has a pH of 2 to 5.5.
10. 10 . The method of claim 1 , wherein the third pretreatment composition is substantially free of gelatin, lanthanide oxide, and/or copper.
11. 11 . The method of claim 1 , wherein the first pretreatment composition, the second pretreatment composition, and/or the third pretreatment composition is substantially free of chromium and/or phosphate.
12. 12 . The method of claim 1 , further comprising contacting the substrate surface with a cleaner composition prior to the contacting with the first pretreatment composition and/or contacting the substrate surface with a film-forming composition.
13. 13 . The method of claim 12 , wherein the film-forming composition comprises an anionic electrodepositable coating composition, a cationic electrodepositable coating composition, a powder coating composition, a liquid coating composition, a primer composition, and/or a topcoat composition.
14. 14 . The method of claim 1 , wherein the substrate comprises magnesium or a magnesium alloy.
15. 15 . A substrate comprising a surface treated with the method of claim 1 .
16. 16 . The substrate of claim 15 , wherein the substrate comprises magnesium or a magnesium alloy.
17. 17 . The substrate of claim 15 , comprising a layer on the substrate surface formed from one of the first, second, or third pretreatment compositions.
18. 18 . The substrate of claim 15 , wherein the substrate comprises a vehicle, a part, an article, a heat exchanger, an appliance, a personal electronic device, and/or a multi-metal article.
19. 19 . The substrate of claim 18 , wherein the vehicle comprises an automobile or an aircraft.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a divisional application of U.S. patent application Ser. No. 17/754,483, filed on Apr. 4, 2022, which is a national phase entry of International Application No. PCT/US2020/045629, filed on Aug. 10, 2020, that claimed the benefit of U.S. Provisional Application No. 62/913,482, filed on Oct. 10, 2019, each of which are incorporated herein by reference. GOVERNMENT CONTRACT This material is based upon work supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy under Cooperative Agreement DE-EE007756 entitled U.S. Automotive Materials Partnership Low-Cost Mg Sheet Component Development and Demonstration Project. FIELD OF THE INVENTION The present invention relates to compositions, systems, and methods for treating a substrate. BACKGROUND OF THE INVENTION The use of protective coatings on metal substrates for improved corrosion resistance and paint adhesion is common. Conventional techniques for coating such substrates include techniques that involve pretreating the metal substrate with chromium-containing compositions. The use of such chromate-containing compositions, however, imparts environmental and health concerns. SUMMARY OF THE INVENTION Disclosed herein is a method of treating a metal substrate comprising: contacting at least a portion of a surface of the substrate with a first pretreatment composition comprising a fluorometallic acid comprising a Group IVA metal and/or a Group IVB metal and free fluoride in an amount of 10 ppm to 500 ppm based on total weight of the first pretreatment composition and having a pH of 1.0 to 4.0 and contacting at least a portion of the substrate surface with a second pretreatment composition comprising a Group IVB metal and free fluoride in an amount of 15 ppm to 200 ppm based on total weight of the second pretreatment composition or a third pretreatment comprising a lanthanide series metal and an oxidizing agent. Also disclosed herein is a substrate comprising a surface, wherein at least a portion of the surface is treated with one of the systems or methods of the present invention. BRIEF DESCRIPTION OF THE FIGURES FIG. 1A shows top/down SEM imaging of a panel pretreated with Pretreatment D in Example 1: FIG. 1B shows a panel pretreated with Pretreatment D in Example 2. FIG. 2A shows an XPS depth profile of a panel treated with Pretreatment D in Example 1: FIG. 2B shows a panel pretreated with Pretreatment D in Example 2. FIG. 3 shows an XPS depth profile of a panel immersed in Pretreatment-I (PT-1) in Example 2 and demonstrates the change in atomic percent of (A) magnesium, (B) oxygen, (C) fluoride, and (D) silicon on ZEK100 magnesium alloy as a function of immersion time. FIGS. 4A-F show FIB-EDS-TEM of a ZEK100 magnesium substrate treated according to Example 2 (PT-1, followed by PT-D). FIG. 4A shows a high-angle annular diffraction TEM micrograph. FIGS. 4B-4F are TEM micrographs overlaid with elemental maps (4B, zirconium; 4C, magnesium; 4D, fluoride; 4E, silicon; 4F, oxygen) as determined by EDS. FIGS. 5A-E show FIB-EDS-TEM Sof an Eform Plus magnesium substrate treated according to Example 12 (PT-1 with no second pretreatment). FIG. 5A shows a high-angle annular diffraction TEM micrograph. FIGS. 5B-4E show are TEM micrographs overlaid with elemental maps (5B, magnesium; 5C, fluoride; 5D, silicon; 5E, oxygen) as determined by EDS. DETAILED DESCRIPTION OF THE INVENTION For purposes of the following detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers such as those expressing values, amounts, percentages, ranges, subranges and fractions may be read as if prefaced by the word “about,” even if the term does not expressly appear. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Where a closed or open-ended numerical range is described herein, all numbers, values, amounts, percentages, subranges and fractions within or encompassed by the numerical range are to be considered as being specifically included in and belonging to the original disclosure of this application as if these numbers, values, amounts, percentages, subranges and fractions had been explicitly written out in their entirety. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approxim