A method for preparing passivated magnesium powder

Abstract

The application discloses a preparation method of passivated magnesium powder and belongs to the field of metal material passivation. The application provides the preparation method of passivated magnesium powder aiming at the problem that magnesium powder in the micro-nano level is difficult to be passivated, magnesium powder in the micro-nano level is first subjected to nitrogen treatment at high temperature to generate magnesium nitride on the surface, then is subjected to fluoride solvent treatment, the surface magnesium nitride is changed into magnesium fluoride, and then is subjected to treatment through a copper-nickel plating solution, and finally a copper / nickel-magnesium-fluoride complex structure film is formed. The method can delay the oxidation of the magnesium powder and improve the safety of the magnesium powder in the transportation, storage and use processes.

Description

Technical Field

[0001] This invention belongs to the field of metal material passivation and relates to a method for preparing passivated magnesium powder. Background Technology

[0002] Micro- and nano-sized magnesium powder (with particle sizes ranging from micrometers to nanometers) has important applications in many fields due to its high specific surface area and unique physicochemical properties. However, its high reactivity also requires special storage methods. Therefore, it must be passivated before it can be safely transported, stored, and used.

[0003] There are many methods for passivating the surface of metallic magnesium, such as organic film protection, electroplating, and chromate passivation film methods. However, these are generally suitable for the surface treatment of magnesium ingots or magnesium alloys. Most of these methods are carried out in aqueous solutions. However, magnesium powder and aqueous systems will react violently, so these methods are not suitable for the surface passivation of magnesium powder, especially micro- and nano-sized magnesium powder.

[0004] Currently, there are two methods for surface treatment of ordinary magnesium granules (generally 80-20 mesh, of which ≤100 mesh accounts for about 6.9%): one is the chemical reaction method, where magnesium on the surface of the magnesium granules reacts with a passivating agent to form a relatively dense reaction product film layer; the other is the surface coating method, which involves coating the surface of the magnesium granules with another substance that does not react with metallic magnesium. Magnesium granules treated with method one have a uniform passivation layer and good passivation effect, but some metallic magnesium is lost; method two does not result in the loss of metallic magnesium, but suffers from uneven passivation and poor passivation effect. Meanwhile, current research mainly focuses on the passivation treatment of magnesium granules used in desulfurization agents, while research on the passivation of micro- and nano-sized magnesium powder remains a challenge in this field. This is because ultrafine magnesium powder has higher reactivity than magnesium granules. Besides self-oxidation in air, it also reacts rapidly with other substances such as water and light oils, severely affecting its application in explosives and propellants. Summary of the Invention

[0005] To address the safety concerns associated with the transportation, storage, and use of micro / nano-sized magnesium powder due to its high activity, this invention provides a method for passivating magnesium powder.

[0006] In a first aspect, the present invention provides a method for preparing passivated magnesium powder, comprising the following steps:

[0007] (1) Micro-nano-sized magnesium powder is nitrided at high temperature to generate magnesium nitride on its surface;

[0008] (2) Magnesium powder with magnesium nitride on its surface is fluorinated to convert the magnesium nitride on its surface into magnesium fluoride;

[0009] (3) Magnesium powder whose surface is converted to magnesium fluoride is subjected to metal film treatment to form a copper-nickel-fluorine film on its surface, thus obtaining passivated magnesium powder.

[0010] Furthermore, micro-nano-level magnesium powder refers to magnesium powder with a median diameter of 5-100 micrometers.

[0011] Furthermore, nitriding at high temperatures to form magnesium nitride on the surface refers to placing micro-nano-sized magnesium powder in a nitrogen environment and treating it at 300–400°C to form magnesium nitride on its surface.

[0012] Furthermore, nitrogen treatment was carried out at 300–400°C for 2 hours.

[0013] Furthermore, the process of converting magnesium nitride on the surface to magnesium fluoride through fluorination treatment involves placing magnesium powder with magnesium nitride on its surface in an aqueous solution of sodium fluoride or ammonium fluoride, and then subjecting it to fluorination treatment to convert the magnesium nitride on the surface to magnesium fluoride.

[0014] Furthermore, the concentration of the aqueous solution of sodium fluoride or ammonium fluoride is 1-10 g / L.

[0015] Furthermore, it is fluorinated at 60-90℃ for 15-60 minutes.

[0016] Furthermore, metallization treatment refers to placing magnesium powder with a surface transformed into magnesium fluoride in a chemical copper-nickel plating solution and reacting it at 30-50℃ for 10-30 minutes to form a copper-nickel-fluorine film on its surface.

[0017] Furthermore, the chemical copper-nickel plating solution consists of 5-15 g / L copper sulfate, 25-75 g / L nickel sulfate, 10-30 g / L potassium sodium tartrate, 1-5 mL hydrofluoric acid, and 15-25 g / L sodium dihydrogen phosphate.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] This invention addresses the challenge of passivating micro- and nano-sized magnesium powder by providing a method for preparing passivated magnesium powder. The method involves first treating the micro- and nano-sized magnesium powder with nitrogen at high temperature to generate magnesium nitride on the surface. Then, after treatment with a fluoride solvent, the surface magnesium nitride is converted into magnesium fluoride. Finally, the powder is treated with a copper-nickel solution to form a copper / nickel-magnesium-fluorine complex film. This method can delay the oxidation of magnesium powder and improve the safety of magnesium powder during transportation, storage, and use. Attached Figure Description

[0020] Figure 1 This is a SEM image of the passivated magnesium powder obtained in Example 1.

[0021] Figure 2 This is a SEM image of the passivated magnesium powder obtained in Comparative Example 1.

[0022] Figure 3This is a SEM image of the passivated magnesium powder obtained in Comparative Example 2.

[0023] Figure 4 This is a SEM image of the passivated magnesium powder obtained in Comparative Example 3. Detailed Implementation

[0024] The present application will be further described below with reference to specific embodiments.

[0025] It should be noted that terms such as "upper", "lower", "left", "right", and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0027] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0028] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0029] As used herein, the term “at least one of…” is intended to be synonymous with “one or more of…”. For example, “at least one of A, B, and C” explicitly includes only A, only B, only C, and combinations thereof.

[0030] Example 1

[0031] 1. Weigh 5g of magnesium powder and place it in a tube furnace. Treat it with nitrogen at 300℃ for 2 hours to obtain precursor A.

[0032] 2. When precursor A was added to a mixed aqueous solution of sodium fluoride (4.0 g / L) and potassium sodium tartrate (8 g / L), no bubbles appeared. After treatment at 60°C for 30 min, the solution was filtered and dried to obtain powder B.

[0033] 3. Add the above powder B to a copper-nickel plating solution. The copper-nickel plating solution consists of 5 g / L copper sulfate, 25 g / L nickel sulfate, 10 g / L sodium potassium tartrate, 1 mL hydrofluoric acid, and 15 g / L sodium dihydrogen phosphate. Stir and add a certain amount of sodium hydroxide solution dropwise to adjust the pH to approximately 6. React at 30-50℃ for 20 minutes. After filtration and washing, passivated magnesium powder is obtained, and its morphology is as follows. Figure 1 As shown.

[0034] The passivated magnesium powder was added to water at 60°C and tested for 60 minutes. No bubbles appeared, indicating that the passivation film was intact and could effectively protect the magnesium powder.

[0035] Comparative Example 1

[0036] 1. Weigh 5g of magnesium powder and add it to a mixed aqueous solution of sodium fluoride (4.0g / L) and potassium sodium tartrate (8g / L). The appearance of bubbles in the solution indicates a partial reaction between the magnesium powder and the aqueous solution. After treatment at 60℃ for 30 minutes, filter and dry to obtain powder B1.

[0037] 2. Add the above powder B1 to the copper-nickel plating solution (same as in Example 1), stir and add a certain amount of sodium hydroxide solution dropwise to adjust the pH to about 6. React at 30-50℃ for 20 minutes. After filtration and washing, passivated magnesium powder is obtained, and its morphology is as follows. Figure 2 As shown.

[0038] When the above passivated magnesium powder was added to water at 60°C and tested for 30 minutes, a large number of bubbles appeared, indicating that the passivation film was generally adequate and could protect the magnesium powder.

[0039] Comparative Example 2

[0040] 1. Weigh 5g of magnesium powder and place it in a tube furnace. Treat it with nitrogen at 300℃ for 2 hours to obtain precursor A2.

[0041] 2. Add the above powder A2 to the copper-nickel plating solution (same as in Example 1), stir and add a certain amount of sodium hydroxide solution dropwise to adjust the pH to about 6. React at 30-50℃ for 20 minutes. After filtration and washing, passivated magnesium powder is obtained, and its morphology is as follows. Figure 3 As shown.

[0042] When the above passivated magnesium powder was added to water at 60°C for 5 minutes, a large number of bubbles appeared, indicating that the passivation film was poor and did not effectively protect the magnesium powder.

[0043] Comparative Example 3

[0044] Weigh 5g of magnesium powder and add it to the copper-nickel plating solution (same as in Example 1). Stir and add a certain amount of sodium hydroxide solution to adjust the pH to about 6. React at 30-50℃ for 20 minutes. After filtration and washing, passivated magnesium powder is obtained, and its morphology is as follows. Figure 4 As shown.

[0045] When the passivated magnesium powder is added to water at 60°C, a large number of bubbles appear, indicating that the passivation film is basically absent and cannot protect the magnesium powder.

[0046] In summary, based on the above experimental phenomena and characterization tests ( Figures 1-4 This demonstrates that the method of Example 1 and the passivation effect of the passivated magnesium powder are superior to those of Comparative Examples 1, 2, and 3.

[0047] The above embodiments are merely preferred embodiments of the present invention, but the implementation of the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, or combinations made without departing from the spirit and principle of the present invention, such as various combinations of solutions in the embodiments, should be considered equivalent replacements and are all within the protection scope of the present invention.

Claims

1. A method for preparing passivated magnesium powder, characterized in that, Includes the following steps: (1) Nitriding of micro-nano-sized magnesium powder at high temperature to generate magnesium nitride on its surface; (2) Magnesium powder with magnesium nitride on its surface is fluorinated to convert the magnesium nitride on its surface into magnesium fluoride; (3) The magnesium powder whose surface is transformed into magnesium fluoride is subjected to metal film treatment to form a copper-nickel-fluorine film on its surface, and passivated magnesium powder is obtained. Among them, micro-nano grade magnesium powder refers to magnesium powder with a median diameter of 5-100 micrometers; Nitriding at high temperature refers to placing micro-nano-sized magnesium powder in a nitrogen environment and treating it with nitrogen at 300~400℃. Fluorination treatment refers to placing magnesium powder with magnesium nitride on its surface in an aqueous solution of sodium fluoride or ammonium fluoride at 60-90℃ for 15-60 minutes. Metal plating treatment refers to placing magnesium powder with a surface transformed into magnesium fluoride in a chemical copper-nickel plating solution and reacting it at 30-50℃ for 10-30 minutes.

2. The preparation method according to claim 1, characterized in that, Nitrogen treatment was carried out at 300~400℃ for 2 hours.

3. The preparation method according to claim 1, characterized in that, The concentration of sodium fluoride aqueous solution or ammonium fluoride aqueous solution is 1-10 g / L.

4. The preparation method according to claim 1, characterized in that, The chemical copper-nickel plating solution consists of 5-15 g / L copper sulfate, 25-75 g / L nickel sulfate, 10-30 g / L potassium sodium tartrate, 1-5 mL hydrofluoric acid, and 15-25 g / L sodium dihydrogen phosphate.

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