WO2021036797A1

WO2021036797A1 - Method for preparing polytannic acid-coated high activity aluminum powder or silicon powder

Info

Publication number: WO2021036797A1
Application number: PCT/CN2020/108855
Authority: WO
Inventors: 张文超; 陈亚杰; 吴刚刚; 俞春培; 王嘉鑫; 陈俊宏; 刘琦
Original assignee: 南京理工大学
Priority date: 2019-08-28
Filing date: 2020-08-13
Publication date: 2021-03-04
Also published as: CN110550990B; CN110550990A

Abstract

Disclosed is a method for preparing a polytannic acid-coated high activity aluminum powder or silicon powder. The method comprises first dissolving a buffering reagent in an organic solvent, adding tannic acid, stirring to obtain a tannic acid buffer solution, then dispersing aluminum powder or silicon powder into the tannic acid buffer solution, and stirring the mixture to allow self-polymerization to obtain the polytannic acid-coated aluminum powder or silicon powder. The method can be utilized with various sources of raw material, is environmentally friendly and safe, is simple and convenient to carry out, and is suitable for industrial production. The prepared composite material comprising aluminum or silicon and polytannic acid in a core-shell structure can effectively prevent rapid oxidation on aluminum or silicon particle surfaces, thus protecting the activity of aluminum or silicon powder. The composite material comprising aluminum or silicon and polytannic acid in a core-shell structure can be added to a solid propellant, and due to the rich carbon content, upon high temperature combustion, the coated polytannic acid can provide additional heat of combustion and promote fast combustion of the aluminum powder or silicon powder, thus enhancing the combustion performance of the solid propellant.

Description

Preparation method of polymerized tannic acid coated high-activity aluminum powder silicon powder

Technical field

The invention belongs to the technical field of energetic materials, and relates to a preparation method of polymerized tannic acid coated high-activity aluminum powder silicon powder.

Background technique

Tannic acid is a plant polyphenol compound that exists in natural plants (tea, wood, oak, etc.) and contains five dimethylol ester groups (Pan L, Wang H, Wu C, et al. .Tannic-acid-coated polypropylene membrane as a separator for lithium-ion batteries[J].ACS applied materials&interfaces,2015,7(29):16003-16010.). Similar to polydopamine coatings, tannic acid coatings can also oxidize and self-polymerize at room temperature to form polymeric tannic acid. The thickness of the resulting polymeric tannic acid coating can be precisely controlled between one to tens of nanometers. A polymer coating material with stable performance at low temperatures (Sileika T S, Barrett D G, Zhang R, et al. Colorless multifunctional coatings inspired by polyphenols found in tea, chocolate, and wine[J]. Angewandte Chemie International Edition ,2013,52(41):10766-10770.).

With the continuous improvement of modern high-performance weapons and ammunition for the comprehensive requirements of energetic materials, energetic materials have higher energy density and energy release rate, better combustion characteristics and higher safety, and have become the field of energetic materials. The main direction of development. As an important additive in the application of solid rocket propellants, metal powder has a special effect on improving the performance of such energetic materials. Compared with ordinary metal powder, micro-nano metal powder has a smaller particle size and the surface-interface of the particle The effect and the small size effect are obvious, resulting in high chemical activity and reactivity on the surface of the metal powder particles. The micro-nano aluminum powder/silica powder has become the most commonly used metal additive in the application of energetic materials because of its high energy density, high combustion heat, high activity, and abundant raw materials (Yao Ergang, Zhao Fengqi, Anting. Nano aluminum powder) The latest progress in the study of surface coating modification. Nanotechnology, 2011,8(2):81-90.).

Micro-nano aluminum/silicon powder has shown great application potential in the application of solid propellants. However, due to the high surface energy of micro-nano-sized particles, in practical applications, the surface of aluminum/silicon fume is very easy to oxidize and form The inert oxide shell layer results in a decrease in the activity of aluminum powder/silicon powder, which seriously affects its use efficiency in solid propellants. A large number of studies have found that after a material material is tightly coated on the surface of aluminum powder/silicon powder particles, the purpose of protecting the high activity of the particles can be achieved. Among them, the coating with carbon is more researched. Zhang Xiaota et al. prepared carbon-coated nano-aluminum powders with a particle size of 10 to 90 nm using a laser-induction composite heating method under a mixed atmosphere of _{CH 4 and inert gas (Zhang Xiaota, Song Wulin, Guo Liangui, etc. Laser-} Preparation of carbon-coated nano-aluminum powder by induction composite heating method[J]. Propulsion Technology, 2007(3):333-336.). Chinese Patent 103611943A discloses a method for preparing carbon-coated nano aluminum powder, which uses nano aluminum/dodecylamine composite to thermally crack at 550-800°C under vacuum conditions to prepare carbon-coated nano aluminum powder. The above-mentioned method has higher requirements for equipment, lower output, lower efficiency, and still has the problem of higher cost, and is not suitable for industrial production applications.

Summary of the invention

The purpose of the present invention is to provide a simple, easy, economical and environmentally friendly preparation method for polymerized tannic acid coated high-activity aluminum powder silicon powder. The method uses plant polyphenol tannins to self-polymerize on the surface of micro/nano-level aluminum powder or silicon powder to form a uniform coating layer, prevent the oxidation of the high-activity aluminum powder and silicon powder itself, thereby maintaining the activity of the particles.

The technical solutions to achieve the purpose of the present invention are as follows:

The preparation method of polymerized tannic acid coated high activity aluminum powder silicon powder includes the following steps:

(1) Preparation of tannic acid-buffer solution:

Dissolve the buffer reagent uniformly in the organic solution, add tannic acid (TA), stir and dissolve to obtain a tannic acid-buffer solution;

(2) Tannic acid oxidation self-polymerization coating high activity aluminum powder or silicon powder:

Disperse the aluminum powder or silicon powder in the tannic acid-buffer solution, stir for self-polymerization, filter, and wash to obtain the aluminum powder or silicon powder coated with polymerized tannic acid.

Preferably, in step (1), the organic solution is any one of methanol, ethanol, isopropanol, n-propanol and acetone and N,N-dimethylformamide or N,N-dimethylformamide. Acetamide is a mixed solution prepared with a volume ratio of 10 to 0.5:1.

Preferably, in step (1), the buffer reagent is selected from tris(hydroxymethyl)aminomethane (Tris), tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl), bis(2-hydroxymethyl) Ethylamino) tris(hydroxymethyl)methane (Bis-Tris) or bis(2-hydroxyethylamino)tris(hydroxymethyl)methane hydrochloride (Bis-Tris-HCl), the buffer reagent is soluble Form a buffer solution with a concentration of 1-30 mmol/L in an organic solvent.

Preferably, in step (1), the mass concentration of tannic acid is 0.1-100 mg/mL.

Preferably, in step (2), the size of the aluminum powder or silicon powder is in the micro-nano range.

Preferably, in step (2), the self-polymerization reaction time is 0.5 to 60 hours.

Compared with the prior art, the present invention has the following advantages:

(1) Polymeric tannic acid is stable at low temperature, which can not only effectively protect the activity of aluminum powder and silicon powder, but also improve the surface electrical properties and surface activity of its particles, which is beneficial to prevent agglomeration between particles; (2) ) Using polymeric tannic acid to form a uniform coating on the surface of highly active aluminum powder or silicon powder, which can effectively prevent its own oxidative deactivation; (3) The coated polymeric tannic acid is rich in carbon, and the resulting composite material is added When the solid propellant undergoes high-temperature combustion, it can provide additional combustion heat to promote the rapid combustion reaction of aluminum powder and silicon powder, thereby improving the combustion performance of the solid propellant; (4) The method of the present invention is a chemical polymerization carried out in the liquid phase. Compared with preparation methods such as vapor deposition, electric arc, laser, etc., the method of the present invention has low equipment requirements, simple reaction, easy operation, and can prepare micro/nano-level aluminum or silicon@polymeric tannic acid core-shell structure composite materials in batches.

Description of the drawings

Figure 1 is a schematic diagram of the preparation process of tannic acid polymerized coated micro/nanoparticles.

FIG. 2 is an SEM image of the nano aluminum powder and the nano aluminum powder after being polymerized and coated with tannic acid in Example 1. FIG.

FIG. 3 is an SEM image of the nano-silicon powder and the nano-silicon powder after being polymerized and coated with tannic acid in Example 2. FIG.

FIG. 4 is a TEM image of the nano aluminum powder and the nano aluminum powder after being polymerized and coated with tannic acid in Example 1. FIG.

FIG. 5 is a TEM image of the nano-silicon powder and the nano-silicon powder after being polymerized and coated with tannic acid in Example 2. FIG.

FIG. 6 is an XRD pattern of the nano aluminum powder and the nano aluminum powder after being polymerized and coated with tannic acid in Example 1. FIG.

FIG. 7 is an XRD pattern of the nano-silicon powder and the nano-silicon powder after being polymerized and coated with tannic acid in Example 2. FIG.

detailed description

The present invention will be further explained by the following examples and drawings.

Example 1

Dissolve 0.22g of Tris buffer reagent in 100mL of methanol/N,N-dimethylformamide solvent with a volume ratio of 1:1, adjust the pH to 8.5, then add 0.20g of tannic acid (TA), stir to dissolve evenly The tannic acid-buffer solution is obtained; then 0.10 g of nano aluminum powder is added, and the self-polymerization reaction is stirred for 1 h, filtered and washed to obtain the nano aluminum powder coated with polymerized tannic acid.

Figures 2 and 4 are respectively the SEM and TEM images of the nano aluminum powder and the polymeric tannic acid coated nano aluminum powder prepared in this example. It is found by comparison that the polymeric tannic acid has formed a uniform coating on the surface of the nano aluminum powder. Cladding. Figure 6 is the XRD pattern of the nano aluminum powder and the polymeric tannic acid coated nano aluminum powder prepared in this example. The comparison shows that the aluminum peak is obvious, and the aluminum is not changed after the polymeric tannic acid coated nano aluminum powder The nature and purity of the powder are better.

Example 2

Dissolve 0.22g of Tris buffer reagent in 100mL of methanol/N,N-dimethylformamide with a volume ratio of 1:1, adjust the pH to 9.6, then add 0.20g of tannic acid (TA), stir to dissolve evenly A tannic acid-buffer solution is obtained; then 0.10 g of nano silicon powder is added, and the self-polymerization reaction is stirred for 6 hours, filtered and washed to obtain a polymerized tannic acid-coated nano silicon powder.

Figures 3 and 5 are respectively the SEM and TEM photos of the nano silicon powder and the polymerized tannic acid coated nano silicon powder prepared in this example. It is found by comparison that the polymerized tannic acid has formed a uniform coating on the surface of the nano silicon powder Floor. Figure 7 shows the XRD patterns of the nano silicon powder and the polymerized tannic acid coated nano silicon powder prepared in this example. The comparison shows that the silicon peak is obvious, while the polymerized tannic acid coated nano silicon powder did not change The nature and purity of silica fume are better.

Example 3

Dissolve 0.22g of Tris buffer reagent in 100mL of methanol/N,N-dimethylformamide solvent with a volume ratio of 1:1, adjust the pH to 8.5, then add 0.20g of tannic acid (TA), stir to dissolve evenly A tannic acid-buffer solution is obtained; then 0.10 g of micron aluminum powder is added, and the self-polymerization reaction is stirred for 1 hour, filtered and washed to obtain a micron aluminum powder coated with polymeric tannic acid.

Example 4

Dissolve 0.22g of Tris buffer reagent in 100mL of methanol/N,N-dimethylformamide with a volume ratio of 1:1, adjust the pH to 9.6, then add 0.20g of tannic acid (TA), stir to dissolve evenly The tannic acid-buffer solution is obtained; then, 0.10 g of micron silicon powder is added, and the self-polymerization reaction is stirred for 6 hours, filtered and washed to obtain the micron silicon powder coated with polymerized tannic acid.

Claims

A preparation method of polymerized tannic acid coated high activity aluminum powder silicon powder is characterized in that it comprises the following steps:

(1) Preparation of tannic acid-buffer solution:

Dissolve the buffer reagent uniformly in the organic solution, add tannic acid, stir and dissolve to obtain a tannic acid-buffer solution;

(2) Tannic acid oxidation self-polymerization coating high activity aluminum powder or silicon powder:

Disperse the aluminum powder or silicon powder in the tannic acid-buffer solution, stir for self-polymerization, filter, and wash to obtain the aluminum powder or silicon powder coated with polymerized tannic acid.
The preparation method according to claim 1, wherein in step (1), the organic solution is any one of methanol, ethanol, isopropanol, n-propanol and acetone and N,N-dimethyl A mixed solution prepared with methyl formamide or N,N-dimethylacetamide in a volume ratio of 10 to 0.5:1.
The preparation method according to claim 1, wherein in step (1), the buffer reagent is selected from the group consisting of tris(hydroxymethyl)aminomethane, tris(hydroxymethyl)aminomethane hydrochloride, and bis(hydroxymethyl)aminomethane hydrochloride. 2-Hydroxyethylamino)tris(hydroxymethyl)methane or bis(2-hydroxyethylamino)tris(hydroxymethyl)methane hydrochloride.
The preparation method according to claim 1 or 3, wherein in step (1), the buffer reagent is dissolved in an organic solvent to form a buffer solution with a concentration of 1-30 mmol/L.
The preparation method according to claim 1, wherein in step (1), the mass concentration of the tannic acid is 0.1-100 mg/mL.
The preparation method according to claim 1, wherein in step (2), the size of the aluminum powder or silicon powder is micro-nano scale.
The preparation method according to claim 1, wherein in step (2), the self-polymerization reaction time is 0.5 to 60 hours.