Preparation method of passivated magnesium powder

Abstract

The invention discloses a preparation method of passivated magnesium powder, and belongs to the field of metal material passivation. Aiming at the problem that micro-nano magnesium powder is difficult to passivate, the invention provides the preparation method of the passivated magnesium powder, the micro-nano magnesium powder is firstly subjected to nitrogen treatment at high temperature to generate magnesium nitride on the surface, then the magnesium nitride on the surface is converted into magnesium fluoride after being treated by a fluoride solvent, and then the magnesium fluoride is treated by a copper-nickel plating solution to obtain the passivated magnesium powder. And finally, the copper / nickel-magnesium-fluorine complex structure film is formed. The method can delay oxidation of the magnesium powder, and meanwhile, the safety of the magnesium powder in the transportation, storage and use processes is improved.

Description

Technical Field

[0001] The invention belongs to the field of metal material passivation and relates to a preparation method of passivated magnesium powder. Background Art

[0002] Micro-nano magnesium powder (particle size ranges from micrometers to nanometers) has important applications in many fields due to its high specific surface area and unique physical and chemical 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 magnesium metal, such as organic film protection, electroplating, and chromate passivation. However, these methods are generally suitable for surface treatment of magnesium ingots or magnesium alloys. Most of these methods are performed in aqueous solution. However, magnesium powder and aqueous systems react violently, making these methods unsuitable for surface passivation of magnesium powder, especially micro-nano-level magnesium powder.

[0004] Currently, there are two methods for surface treatment of ordinary magnesium granules (generally 80-20 mesh, with approximately 6.9% of these being ≤100 mesh): a chemical reaction method, in which the magnesium on the surface of the granules reacts with a passivating agent to form a dense film of reaction products; and a surface coating method, in which the surface of the granules is coated with another substance that does not react with the metallic magnesium. Method 1 produces a uniform passivation layer on the granules, resulting in good passivation, but some metallic magnesium is lost. Method 2 does not result in loss of metallic magnesium, but suffers from uneven and poor passivation. Currently, research focuses on the passivation of magnesium granules used in desulfurization agents, while research on the passivation of micro- and nano-scale magnesium powders remains a challenge in this field. This is because ultrafine magnesium powder is more active than magnesium granules. Besides self-oxidation in air, it also rapidly reacts with other substances, such as water and light oil, severely impacting its application in explosives and propellants. Summary of the Invention

[0005] In view of the problems that micro-nano magnesium powder is highly active and unsafe in transportation, storage and use, the present 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) Nitriding micro-nano magnesium powder at high temperature to generate magnesium nitride on its surface;

[0008] (2) subjecting the magnesium powder having magnesium nitride formed on its surface to a fluorination treatment, thereby converting the magnesium nitride on its surface into magnesium fluoride;

[0009] (3) The magnesium powder whose surface is converted into magnesium fluoride is subjected to a metal film coating treatment to form a copper-nickel-fluorine film on its surface to obtain a passivated magnesium powder.

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

[0011] Furthermore, performing nitriding treatment at high temperature to generate magnesium nitride on the surface thereof means placing micro-nano-level magnesium powder in a nitrogen environment and performing nitrogen treatment at 300-400° C. to generate magnesium nitride on the surface thereof.

[0012] Furthermore, nitrogen treatment was performed at 300-400° C. for 2 h.

[0013] Furthermore, converting the magnesium nitride on its surface into magnesium fluoride through fluoridation treatment means placing magnesium powder with magnesium nitride generated on its surface in a sodium fluoride or ammonium fluoride aqueous solution and converting the magnesium nitride on its surface into magnesium fluoride through fluoridation treatment.

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

[0015] Furthermore, the fluorination treatment is carried out at 60-90°C for 15-60 minutes.

[0016] Furthermore, the metal film plating treatment refers to placing the magnesium powder whose surface is converted into magnesium fluoride in a chemical copper-nickel plating solution, reacting at 30-50° C. for 10-30 minutes, so as to form a copper-nickel-fluorine film on the surface.

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

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

[0019] This invention addresses the difficulty of passivating micro- and nano-scale magnesium powder. It provides a method for preparing passivated magnesium powder. The micro- and nano-scale magnesium powder is first treated with nitrogen at high temperature to form magnesium nitride on the surface. The powder is then treated with a fluoride solvent to convert the magnesium nitride to magnesium fluoride. The powder is then plated with a copper-nickel solution to form a copper / nickel-magnesium-fluorine complex film. This method can slow oxidation of the magnesium powder and improve safety during transportation, storage, and use. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0023] Figure 4 This is the SEM photo of the passivated magnesium powder obtained in Comparative Example 3. DETAILED DESCRIPTION

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

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

[0026] Unless defined otherwise, 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 belongs; the term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0027] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents or instruments used, if the manufacturer is not specified, are commercially available conventional products.

[0028] As used herein, the term "about" is used to provide flexibility and imprecision associated with a given term, measurement, or value. One 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 of each thereof.

[0030] Example 1

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

[0032] 2. The precursor A was added to a mixed aqueous solution of 4.0 g / L sodium fluoride and 8 g / L potassium sodium tartrate. No bubbles were formed. After treatment at 60°C for 30 minutes, the powder B was filtered and dried.

[0033] 3. Add the powder B to the copper-nickel plating solution. The composition of the copper-nickel plating solution is 5g / L copper sulfate, 25g / L nickel sulfate, 10g / L potassium sodium tartrate, 1mL hydrofluoric acid, and 15g / L sodium dihydrogen phosphate. Stir and drop a certain amount of sodium hydroxide solution. Adjust the pH to about 6. React at 30-50°C for 20min. After filtering and washing, the passivated magnesium powder is obtained. Its morphology effect is as follows: Figure 1 shown.

[0034] The above passivated magnesium powder was added to 60℃ water 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 4.0g / L sodium fluoride and 8g / L potassium sodium tartrate. The presence of bubbles in the solution indicates a partial reaction between the magnesium powder and the aqueous solution. After incubation at 60°C for 30 minutes, filter and dry to obtain powder B1.

[0037] 2. Add the powder B1 to the copper-nickel plating solution (same as in Example 1), add a certain amount of sodium hydroxide solution dropwise with stirring, adjust the pH to about 6, react at 30-50°C for 20 minutes, filter and wash to obtain the passivated magnesium powder, the morphology of which is as follows: Figure 2 shown.

[0038] The above passivated magnesium powder was added to 60℃ water and tested for 30 minutes. A large number of bubbles appeared, indicating that the passivation film was normal and could protect the magnesium powder.

[0039] Comparative Example 2

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

[0041] 2. Add the above powder A2 to the copper-nickel plating solution (same as in Example 1), add a certain amount of sodium hydroxide solution dropwise with stirring, adjust the pH to about 6, react at 30-50°C for 20 minutes, filter and wash to obtain passivated magnesium powder, the morphology of which is as follows: Figure 3 shown.

[0042] The above passivated magnesium powder was added to 60℃ water and tested for 5 minutes. A large number of bubbles appeared, indicating that the passivation film was poor and failed to 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 drop a certain amount of sodium hydroxide solution, adjust the pH to about 6, react at 30-50°C for 20min, filter and wash to obtain passivated magnesium powder, the morphology of which is as follows: Figure 4 shown.

[0045] When the above-mentioned passivated magnesium powder is added to 60°C water, a large number of bubbles appear, indicating that there is basically no passivation film and it cannot protect the magnesium powder.

[0046] In summary, based on the above experimental phenomena and characterization tests ( Figures 1 to 4 ), indicating that the passivation effect of the method and passivation magnesium powder of Example 1 is better than that of the passivation magnesium powder of Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0047] The above-mentioned implementation cases are only preferred implementation cases in the present invention, but the implementation methods of the present invention are not limited to the above-mentioned implementation cases. For example, various combinations of the schemes in the embodiments and any other changes, modifications, substitutions, and combinations made without departing from the spirit and principles of the present invention should be equivalent replacement methods and are within the scope of protection of the present invention.

Claims

1. A method for preparing passivated magnesium powder, characterized in that: The steps include: (1) Nitriding micro-nano magnesium powder at high temperature to generate magnesium nitride on its surface; (2) The magnesium powder with magnesium nitride formed on the surface is subjected to fluorination treatment to convert the magnesium nitride on the surface into magnesium fluoride; (3) The magnesium powder whose surface is converted into magnesium fluoride is subjected to a metal coating treatment to form a copper-nickel-fluorine film on its surface to obtain a passivated magnesium powder.

2. The method according to claim 1, wherein Micro-nano grade magnesium powder refers to magnesium powder with a median diameter of 5-100 microns.

3. The method according to claim 1, wherein Nitriding treatment at high temperature refers to placing micro-nano-level magnesium powder in a nitrogen environment and performing nitrogen treatment at 300~400℃.

4. The method according to claim 3, wherein Treat with nitrogen at 300~400℃ for 2h.

5. The method according to claim 1, wherein Fluoridation treatment refers to placing magnesium powder with magnesium nitride formed on the surface in an aqueous solution of sodium fluoride or ammonium fluoride.

6. The method according to claim 5, wherein The concentration of the sodium fluoride or ammonium fluoride aqueous solution is 1-10 g / L.

7. The method according to claim 5, wherein Fluorination treatment at 60-90°C for 15-60 minutes.

8. The method according to claim 1, wherein The metal film plating treatment refers to placing magnesium powder whose surface is converted into magnesium fluoride in a chemical copper-nickel plating solution and reacting it at 30-50° C. for 10-30 minutes.

9. The method according to claim 8, wherein The chemical copper-nickel plating solution is composed 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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