Method for treating metal surfaces, treated metal, phosphating additive, and method for phosphating metal surfaces

Abstract

The present invention pertains to the fields of materials engineering and chemistry. More specifically, the invention discloses a method for treating metal surfaces, as well as treated metal for products of economic interest. The invention further relates to a phosphating additive and a method for phosphating metal surfaces comprising mixing said additive with a phosphating agent. The treatment method of the present invention has surprising results for the treatment of metal surfaces. In addition, it enables replacement of the widely used phosphating process for treating metal surfaces, also providing a process with fewer treatment stages than conventional phosphating. This results in reagent savings and reduced waste generation, aligning with ESG (environmental, social and governance) practices.

Description

Descriptive Report of Invention Patent Method for treating metal surfaces, treated metal, phosphatizing additive and method of adding phosphatizing agent to metal surfaces Field of Invention

[0001] The present invention is in the field of materials and chemical engineering. More specifically, the invention discloses a method for treating metal surfaces, as well as a treated metal for products of economic interest. It also discloses a phosphating additive and a method for adding a phosphating agent to metal surfaces, comprising a mixture of said additive and a phosphating agent. The treatment method of the present invention is a method for treating a metal surface with surprising results. Furthermore, it allows for the replacement of the widely used phosphating process for treating metal surfaces, providing a process with fewer treatment steps than traditional phosphating, resulting in reagent savings and reduced waste production, in compliance with ESG (Environmental, Social, and Governance) practices. Background of the Invention

[0002] In the numerous applications involving metals, such as iron and steel, there is also the problem of corrosion. Corrosion is a natural process resulting from the deterioration of metals through oxidation-reduction reactions.

[0003] Among the methods for greater protection of metals against corrosion is phosphating, which can be understood as a treatment that promotes the conversion of metallic species on a metal's surface, typically applied to iron and steel. Phosphating creates a chemical conversion coating on the surface, protecting the metal matrix against corrosion in contact with external agents. In conventional phosphating, phosphates are formed. insoluble metals on the surface (such as Zinc, Nickel, Manganese or Calcium).

[0004] However, metal solutions, such as nickel, can pose significant occupational and environmental risks. During handling and application of nickel solutions, inhalation and contact with skin or eyes may occur, and studies have shown that nickel has carcinogenic potential. Furthermore, the proper treatment and disposal of these nickel solutions represent a significant environmental liability. Therefore, the search for safer and more environmentally friendly metal surface treatments is ongoing, representing a current trend toward compliance with ESG (Environmental, Social, and Governance) best practices.

[0005] The technical problem of obtaining treatments that are efficient compared to conventional treatments, such as phosphating, and, at the same time, more environmentally and occupationally friendly must be addressed so that technologies are developed in accordance with best ESG (Environmental, Social and Governance) practices.

[0006] In the search for the state of the art in scientific and patent literature, the following documents were found that relate to the topic, without however anticipating or suggesting it:

[0007] Co-pending patent application BR1 12023003019-6, entitled "Niobium Nanoparticle Preparation, Use and Process for Obtaining It," was filed by Fras-le and shares common inventors with the present invention. This document describes a niobium nanoparticle preparation obtained by a top-down approach. This preparation also includes the following technical characteristics: particles entirely in the nanometer particle size range; high purity; and industrial-scale production at an affordable cost. This nanometric powder preparation has very high purity, since the process does not add impurities or lead to the formation of reaction products, as is the case with bottom-up processes. up (or synthesis) of the state of the art. Said document does not disclose a method for treating metal surfaces, as in the present invention.

[0008] Yamaguti, RCL's (2012) doctoral thesis, entitled "Evaluation of alternatives to the use of nickel and chromates in the tricationic phosphating process applied to carbon steel," suggests the use of niobium and ammonium oxalate in place of nickel compounds in tricationic phosphate baths. However, the aforementioned document does not disclose a method for treating metal surfaces, as defined in the present invention, that can completely replace phosphating techniques for preparing metal surfaces for painting. Additionally, it is important to emphasize that the aforementioned prior art document reinforces that niobium pentoxide is a very insoluble and slightly reactive compound, discouraging the specific application of niobium pentoxide.

[0009] The dissertation by dos Santos, FS (2016) entitled “Study of the addition of polyethylene glycol in hexafluorozirconic acid in the formation of the nanoceramic layer” mentions the use of conversion layers based on hexafluorozirconic or hexafluorotitanic acids. However, the aforementioned document does not disclose a method for treating metal surfaces, as defined in the present invention.

[0010] The article by Adhikari et al. (2011) entitled “Hexafluorozirconic acid-based surface pretreatments: Characterization and performance assessment” investigates the use of a novel phosphate-free surface treatment based on hexafluorozirconic acid for corrosion protection. However, the aforementioned document does not disclose a method for metal surface treatment, as defined in the present invention.

[0011] Thus, the present invention solves the problems of the state of the art by creating a method for metal surface treatment with surprising results and in compliance with ESG practices, reducing the production of waste and minimizing the occupational risks of handling and contact with Nickel solutions.

[0012] From what can be inferred from the literature researched, no documents were found anticipating or suggesting the teachings of the present invention. Summary of the Invention

[0013] The metal surface treatment method of the present invention has surprisingly enabled the production of treated metals that exhibit greater corrosion protection than pretreatment baths known in the prior art.

[0014] The method of the present invention is a method for treating a metal surface with surprising results. Furthermore, it allows for the replacement of the widely used phosphating process for treating metal surfaces, providing a process with fewer treatment steps than traditional phosphating, resulting in reagent savings and reduced waste production, in compliance with ESG (Environmental, Social, and Governance) practices.

[0015] Furthermore, the method of the present invention makes it possible to obtain a performance similar to the tricationic phosphate layers formed by prior art techniques, however, with the surprising advantage that the application of the solution of the present invention can be carried out at room temperature while conventional phosphating techniques are carried out at temperatures in the range of 35-60°C.

[0016] In a first aspect, the present invention provides a method for treating a metal surface comprising at least one step of contacting a metal with a solution comprising Niobium species and fluorinated inorganic acid.

[0017] In a second aspect, the present invention features a treated metal comprising at least one surface treated by the metal surface treatment method of the present invention.

[0018] In a third aspect, the present invention provides a method of adding a metal surface phosphatizer comprising at least a step of mixing a solution comprising Niobium species and a fluorinated inorganic acid with a phosphatizer.

[0019] In a fourth aspect, the present invention provides a phosphating additive comprising a solution comprising Niobium species and fluorinated inorganic acid.

[0020] These and other objects of the invention will be immediately appreciated by those skilled in the art and will be described in detail below. Brief Description of the Figures

[0021] The following figures are presented:

[0022] Figure 1 shows a Nyquist graph generated from an EIE (Electrochemical Impedance Spectroscopy) test that proves the protective power of the surface treatment method of the present invention.

[0023] Figure 2 shows a solubilization curve of Niobium pentoxide in hexafluorozirconium acid (time x temperature). Detailed Description of the Invention

[0024] The metal surface treatment method of the present invention has surprisingly enabled the production of treated metals that exhibit greater corrosion protection than pretreatment baths known in the prior art.

[0025] The method of the present invention is a method for treating a metal surface with surprising results. Furthermore, it allows for the replacement of the widely used phosphating process for treating metal surfaces, providing a process with fewer treatment steps than traditional phosphating, resulting in reagent savings and reduced waste production, in compliance with ESG (Environmental, Social, and Governance) practices.

[0026] In the context of the present invention, the expression “Niobium species” encompasses various chemical entities containing Niobium, including Niobium metallic, oxides, hydrates, hydrides, carbides, or nitrides of Niobium, Niobium iron, or Niobium alloyed with other metals or transition metals, or combinations thereof. Also includes Niobium pentoxide (Nb20s), NbC, NbO, Niobium oxalate, and niobic acid. May be a mass quantity of microparticles, submicroparticles, or nanoparticles.

[0027] In the context of the present invention, the expression “fluorinated inorganic acid” encompasses various chemical entities of fluorinated acids, including hexafluorozirconium acid, hexafluorotitanic acid, hexafluorosilicic acid, or combinations or salts thereof.

[0028] In the context of the present invention, the term "degree of amortization" should be understood as the extent to which a material presents a predominantly disordered phase, in contrast to predominantly monocrystalline and polycrystalline phases. "Amortization" can be understood as a process of loss of long-range ordering of atoms, molecules, or ions in the crystal structure of a given material, which may also present short-range ordering.

[0029] In a first aspect, the present invention provides a method for treating a metal surface comprising at least one step of contacting a metal with a solution comprising Niobium species and fluorinated inorganic acid.

[0030] In one embodiment of the method, said solution is an acidic solution.

[0031] In one embodiment of the method, said acidic solution comprises hydrofluoric acid.

[0032] In one embodiment of the method, said Niobium species is composed of Nb206, NbO2, NbO, Niobium oxalate, niobic acid, or combinations thereof.

[0033] In one embodiment of the method, said Niobium species is composed of Niobium pentoxide.

[0034] Compared to other metal solutions such as Nickel commonly used in the state of the art, Niobium pentoxide presents the additional advantage of being biocompatible.

[0035] In one embodiment of the method, said Niobium species comprises a mass quantity comprising a significant degree of amortization.

[0036] In one embodiment of the method, said Niobium species is composed of a mass quantity of Nb20s nanoparticles comprising a significant degree of buffering.

[0037] In one embodiment, said mass quantity of particles comprises a degree of amortization of at least 19%.

[0038] In one embodiment, said mass amount of particles preferably comprises a degree of amortization of at least 20%, more preferably at least 25%, more preferably at least 30%, more preferably at least 35%, more preferably at least 39%, more preferably at least 40%, more preferably at least 45%, more preferably at least 50%, more preferably a degree of amortization of at least 55%, more preferably at least 60%, more preferably at least 65%, and even more preferably a degree of amortization of at least 70%. In one embodiment, the degree of amortization is at least 71%, more preferably at least 72%, more preferably at least 73%. In a non-limiting embodiment, the degree of amortization is 74%.

[0039] In one embodiment, said mass amount of particles preferably comprises a degree of amortization of at least 39%, preferably a degree of amortization of at least 55% and even more preferably a degree of amortization of at least 70%.

[0040] In one embodiment of the method, said fluorinated inorganic acid is composed of hexafluorozirconium acid, hexafluorotitanic acid, hexafluorosilicic acid, or combinations thereof.

[0041] In one embodiment of the method, said fluorinated inorganic acid is composed of hexafluorozirconium acid.

[0042] In one embodiment of the method, the step of contacting a metal with the solution is performed at room temperature.

[0043] In a second aspect, the present invention features a treated metal comprising at least one surface treated by the metal surface treatment method of the present invention.

[0044] In one embodiment, said treated metal is composed of a matrix of gray cast iron, nodular cast iron, carbon steel, microalloyed steel, stainless steel, aluminum, copper, or alloys or combinations thereof.

[0045] In one embodiment, said treated metal is composed of a carbon steel matrix.

[0046] In a third aspect, the present invention provides a method of adding a metal surface phosphatizer comprising at least one step of mixing a solution comprising Niobium species and a fluorinated inorganic acid with a phosphatizer.

[0047] In one embodiment of the method, said Niobium species comprises a mass quantity comprising a significant degree of amortization.

[0048] In a fourth aspect, the present invention provides a phosphating additive comprising a solution comprising Niobium species and fluorinated inorganic acid.

[0049] In one embodiment of the additive, said solution comprises 1% by mass of the Niobium species in the fluorinated inorganic acid.

[0050] In one embodiment of the additive, said Niobium species is composed of Nb206, NbO2, NbO, Niobium oxalate, niobic acid or combinations thereof.

[0051] In one embodiment of the additive, said Niobium species is composed of Niobium pentoxide.

[0052] In one embodiment of the additive, said Niobium species comprises a mass quantity comprising a significant degree of amortization.

[0053] In one embodiment of the additive, said Niobium species is composed of a mass quantity of Nb20s nanoparticles comprising a significant degree of amortization.

[0054] In one embodiment, said mass quantity of particles comprises a degree of amortization of at least 19%.

[0055] In one embodiment, said mass amount of particles preferably comprises a degree of amortization of at least 20%, more preferably at least 25%, more preferably at least 30%, more preferably at least 35%, more preferably at least 39%, more preferably at least 40%, more preferably at least 45%, more preferably at least 50%, more preferably a degree of amortization of at least 55%, more preferably at least 60%, more preferably at least 65%, and even more preferably a degree of amortization of at least 70%. In one embodiment, the degree of amortization is at least 71%, more preferably at least 72%, more preferably at least 73%. In a non-limiting embodiment, the degree of amortization is 74%.

[0056] In one embodiment, said mass amount of particles preferably comprises a degree of amortization of at least 39%, preferably a degree of amortization of at least 55% and even more preferably a degree of amortization of at least 70%.

[0057] In one embodiment of the additive, said fluorinated inorganic acid is composed of hexafluorozirconium acid, hexafluorotitanic acid, hexafluorosilicic acid, or combinations thereof.

[0058] In one embodiment of the additive, said fluorinated inorganic acid is composed of hexafluorozirconium acid.

[0059] Thus, the treatment method of the present invention makes it possible to replace conventional phosphating where insoluble metallic phosphates are formed on the surface (such as Zinc, Nickel, Manganese or Calcium), promoting environmental protection and, at the same time, greater power. protective against corrosion of parts treated by the method of the present invention, representing savings in reagents and lower production of waste in accordance with ESG (Environmental, Social and Governance) practices.

[0060] Furthermore, the method of the present invention makes it possible to obtain a performance similar to the tricationic phosphate layers formed by prior art techniques, however, with the surprising advantage that the application of the solution of the present invention can be carried out at room temperature while conventional phosphating techniques are carried out at temperatures in the range of 35-60°C.

[0061] Examples

[0062] The examples shown here are intended only to exemplify some of the various ways of carrying out the invention, without, however, limiting its scope.

[0063] Example 1 - Protective power of the treatment method of the present invention

[0064] In this embodiment, an EIE (Electrochemical Impedance Spectroscopy) test is performed, which proves the effectiveness of the protective power of the method for treating the metal surface of the present invention, comprising at least one step of contacting a metal with a solution comprising Niobium species and Zirconium species.

[0065] Niobium pentoxide particles were dissolved in hexafluorozirconium acid solution under heat application in the temperature range of 60 to 100°C, and Niobium pentoxide is quite soluble in hydrofluoric acid (HF) which is present in hexafluorozirconium acid.

[0066] Solutions of 1% and 2% by weight of niobium pentoxide particles in hexafluorozirconium acid were prepared. Steel parts were immersed for 1 min and 3 min in the 1% by weight solution, and for 1 min in the 2% by weight solution of niobium pentoxide.

[0067] Nanometric particles of niobium pentoxide produced by mechanosynthesis were used, as described in the patent application BR1 12023003019-6 deposited by Fras-le.

[0068] Without the desire to be tied to theory, it is understood that the samples subjected to 12 hours of grinding, which present a higher degree of amortization (74%), contribute to the surprising effects presented.

[0069] The Nyquist plot in Figure 1 shows that the increase in protection with the incorporation of niobium pentoxide nanoparticles occurs on the order of hundreds of ohms per square centimeter. The higher and wider the curve, the greater the corrosion protection potential of the pretreatment bath. The reference product offers 1,000 hours of corrosion resistance in a salt spray chamber on aluminum test specimens.

[0070] Furthermore, the method of the present invention achieved the presented results with only three baths, as opposed to five baths that are used in conventional phosphating methods.

[0071] Figure 2 shows a solubilization curve of niobium pentoxide in hexafluorozirconium acid (time x temperature). To incorporate solid niobium pentoxide powder to add to nanoceramics, a dilution of 1% and 2% by mass of dry niobium pentoxide in hexafluorozirconium acid was used until the product was completely solubilized.

[0072] The method of the present invention was tested on steel, aluminum, and nodular cast iron, with and without machining. In all cases, the corrosion resistance of the pitted specimen was at least twofold higher.

[0073] The method of the present invention not only made it possible to eliminate the use of metallic solutions that present occupational risks, but also made it possible to avoid the use of Zinc salts, further contributing to the saving of reagents and lower production of waste in accordance with ESG (Environmental, Social and Governance) practices.

[0074] Those skilled in the art will appreciate the knowledge presented herein and will be able to reproduce the invention in the presented embodiments and in other variants and alternatives, covered by the scope of the following claims.

Claims

Claims 1. Method for treating a metal surface characterized by comprising at least one step of contacting a metal with a solution comprising Niobium species and a fluorinated inorganic acid.

2. Method for treating a metal surface according to claim 1, characterized in that said solution is an acidic solution.

3. Method for treating a metal surface according to claim 1, characterized in that said Niobium species is composed of Nb206, NbO2, NbO, Niobium oxalate, niobic acid or combinations thereof.

4. Method for treating a metal surface according to claim 3, characterized in that said species of Niobium comprises a mass quantity comprising a significant degree of amortization.

5. Method for treating a metal surface according to claim 1, characterized in that said fluorinated inorganic acid is composed of hexafluorozirconium acid, hexafluorotitanic acid, hexafluorosilicic acid or combinations thereof.

6. Method for treating a metal surface according to claim 1, characterized in that the step of contacting a metal with the solution is performed at room temperature.

7. Treated metal characterized by comprising at least one surface treated by the method for treating metal surfaces as defined in claim 1.

8. Metal treated according to claim 7, characterized in that the metal is composed of a matrix of gray cast iron, nodular cast iron, carbon steel, microalloyed steel, stainless steel, aluminum, copper or alloys or combinations thereof.

9. Phosphating additive, characterized by comprising a solution comprising Niobium species and fluorinated inorganic acid.

10. Method of adding a metal surface phosphatizer characterized comprising at least one step of mixing a phosphatizer additive as defined in claim 9 with a phosphatizer.

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