Combustible foil for area-type infrared decoy flare and preparation method therefor

Abstract

A combustible foil for an area-type infrared decoy flare and a preparation method therefor. During preparation, an ignition agent and a combustion agent are coated on a metal foil by means of an adhesive, and then the ignition agent is activated, such that the combustible foil is obtained; the combustible foil is stored in an inert atmosphere glove box for subsequent use. The combustible foil can rapidly and spontaneously combust in the air, and the heat radiation temperature can reach 1300 K or above.

Description

Combustible foil for surface-source infrared jamming bomb and preparation method thereof Technical Field

[0001] The invention relates to infrared jamming technology, in particular to a combustible foil for a surface-source infrared jamming bomb and a preparation method thereof. Background Art

[0002] The continuous advancement of modern optoelectronic technologies, such as infrared imaging and spectral recognition, has driven the rapid development and improvement of new infrared detection and guidance technologies. Infrared-guided missiles have gradually demonstrated their unique advantages and immense combat power. These guided weapons have significantly improved their accuracy and impact on their intended targets. In modern warfare, combat aircraft, ships, armored vehicles, and other ground fortifications are potentially a serious threat to combat aircraft, ships, and other combat facilities. Infrared-guided missiles have become the most threatening "enemy" to combat aircraft, ships, and other combat facilities. Faced with the challenging survival challenges facing military targets on the modern battlefield, passive jamming techniques, which use mimetic decoys as decoys to disrupt enemy detection and guidance, are gaining increasing attention. It is anticipated that infrared decoys will continue to employ targeted countermeasures and undergo continuous upgrades.

[0003] Infrared jamming bomb materials play a very important role as equipment decoys. The materials can be used to cover the paths of combat weapons such as aircraft passing through a specific area to disperse anti-aircraft firepower and prevent anti-aircraft artillery attacks. Traditional point-source infrared jamming bomb materials are infrared pyrotechnic agents composed of magnesium (Mg), polytetrafluoroethylene (PTFE) and fluororubber (Viton). The current method for producing magnesium-polytetrafluoroethylene mixtures requires the use of solvents that are highly polluting and flammable. For example, in a known method, the mixture is prepared by evaporating an adhesive on the mixture using a solvent of acetone or methyl ethyl ketone, and the mixture is dried and solidified by pressing or extrusion to form a medicament. Acetone and methyl ethyl ketone are flammable, so the materials used and the production process are extremely dangerous and not conducive to environmental protection. In addition, in actual application, infrared jamming bomb materials need to have characteristics such as fast combustion response time and combustion temperature and time that meet the requirements. Most point-source infrared jamming bomb materials have short combustion time and low combustion temperature, which cannot meet actual needs.

[0004] Germany earlier invented a flammable foil bomb that produces high-intensity infrared radiation, designed to disrupt incoming infrared-guided missiles and deflect them from their targets. This jammer is made from thin paper or metal foil coated with polyvinyl chloride glue, a softener called dioctyl phthalate, a combustible agent, and a dispersant. The combustible agent is typically magnesium powder, aluminum powder, or red phosphorus powder. U.S. Patent No. 4,624,186A describes a composite jamming material that uses a metal foil substrate with a layer of burning paste pressed onto its surface. The burning rate is controlled by adjusting the amount of combustible material in the paste, enabling simultaneous interference with infrared and millimeter waves. U.S. Patent No. 6,013,144A describes another composite material, using a carbon fiber substrate and a self-igniting coating applied via vapor deposition. This self-igniting coating can provide infrared radiation during the continuous combustion process, and the intensity and wavelength of the infrared radiation can be changed by adjusting the formula composition. It is a highly controllable bait material; U.S. Patent US6193814B1 introduces a composite material with a new process. It uses tin-plated tinplate as the base and coats its surface with an active metal coating. When heated to 700-900°C under oxygen-isolating conditions, a self-igniting composite material is formed.

[0005] As can be seen from this, the existing technology directly uses raw materials that can spontaneously combust in air for production and processing, resulting in complex production processes and relatively dangerous processing. Therefore, there is an urgent need to develop bait materials that are less dangerous, environmentally friendly, and can achieve both long burning times and high burning temperatures.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to solve the shortcomings of the prior art in the production of equipment bait, such as the production materials and processes are extremely dangerous and not conducive to environmental protection, and the resulting bait has a short burning time and low burning temperature. The present invention provides a combustible foil for surface-source infrared jamming bombs and a preparation method thereof.

[0008] Inventive concept

[0009] Research has shown that flammable foil is a new generation of interference material for countering infrared sources and can spontaneously combust rapidly in the air. Based on the actual needs of surface-source infrared decoy bombs, the present invention has developed a flammable foil with a thermal radiation temperature of over 1300K, an ignition time of ≤1.0s, and adapted to the assembly requirements of infrared jamming bombs.

[0010] To achieve the above objectives, the present invention provides the following technical solutions.

[0011] A combustible foil for surface-source infrared jamming bombs is special in that it comprises a metal foil and a mixture coated on the surface of the metal foil, wherein the mixture comprises an adhesive, an igniter and a combustion agent; the adhesive comprises silicate; and the igniter is a material that can spontaneously combust in air.

[0012] Furthermore, the igniter is formed by activating a nickel-aluminum alloy or an iron-aluminum alloy with a strong alkaline solution, wherein the aluminum content of the nickel-aluminum alloy or the iron-aluminum alloy is 30wt.%-60wt.%; and the mass ratio of the nickel-aluminum alloy / iron-aluminum alloy to the combustion agent is 1:(0.1-0.5). Too little aluminum in the nickel-aluminum alloy or the iron-aluminum alloy will result in the igniter releasing too little heat and failing to ignite. Too much aluminum will cause the adhesive, sodium silicate or methyl silicate, to react with a strong base and weak acid salt, producing gas, causing the adhesive to become jelly-like and unapplicable.

[0013] Furthermore, the adhesive also includes a viscosity enhancer, which is one or more of sodium tripolyphosphate, polyvinyl alcohol, hydroxyethyl cellulose, and methyl cellulose; the silicate is one or both of sodium silicate and / or potassium silicate, with a modulus of 2.0-3.4; and the combustible agent includes an alloy powder composed of one or more of magnesium, zinc, titanium, and boron, wherein the impurity content is less than 20% of the total mass. The modulus of the silicate is preferably 2.0-3.4. A too high modulus will result in excessively high viscosity of the adhesive, making it difficult to apply to the metal foil. A too low modulus will result in excessive alkalinity of the sodium silicate or potassium silicate, which will easily react with the iron-aluminum alloy and reduce the viscosity of the adhesive. The viscosity enhancer is used to increase the viscosity of the adhesive and improve the stability of the combustible foil.

[0014] Furthermore, the ignition agent is formed by activating an iron-aluminum alloy through a NaOH solution, and the combustion agent is magnesium; the adhesive is sodium silicate, and the viscosity enhancer is sodium tripolyphosphate.

[0015] At the same time, the present invention also provides a method for preparing a combustible foil for a surface-source infrared jamming bomb, comprising the following steps:

[0016] Step 1) Preparation of alloy slurry

[0017] The adhesive and energetic alloy powder are uniformly mixed to obtain alloy slurry; the adhesive is a silicate aqueous solution, and the energetic alloy powder includes an ignition agent raw material and a combustion agent;

[0018] Step 2) coating and calcination

[0019] Step 2.1) uniformly coating the energetic slurry obtained in step 1) on the surface of the metal foil, and drying to remove moisture from the energetic slurry;

[0020] Step 2.2) calcining the metal foil under an inert atmosphere and cooling it to room temperature for later use;

[0021] Step 3) Immersing the metal foil obtained in step 2) in a strong alkaline solution to activate the igniter raw material to form an igniter, taking it out after activation, washing it with water and vacuum drying it to obtain a combustible foil, and storing the combustible foil in an inert atmosphere glove box.

[0022] Furthermore, in step 2.1), the drying temperature is ≤ 60°C and the drying time is ≤ 1 hour. After drying, the metal foil is cut according to different requirements. In step 2.2), the calcination temperature is 400°C-700°C and the calcination time is 10 minutes-60 minutes, and the calcination atmosphere is nitrogen. However, if the calcination temperature is too low, the silicate foaming is insufficient, and the adhesion of the energetic alloy powder cannot meet the requirements. If the calcination temperature is too high, the surface layer of the energetic alloy powder on the metal foil will peel off due to high-temperature sintering. Therefore, a temperature of 400°C-700°C is preferably used for better results.

[0023] Furthermore, step 1) is specifically as follows:

[0024] Step 1.1) dissolving a silicate, or a silicate and a viscosity enhancer, in water to prepare a silicate aqueous solution having a mass concentration of 20 wt.% to 30 wt.% as an adhesive; the silicate is one or both of sodium silicate and potassium silicate, and the modulus of the sodium silicate or potassium silicate is 2.0 to 3.4; the viscosity enhancer is one or more of sodium tripolyphosphate, polyvinyl alcohol, hydroxyethyl cellulose, and methyl cellulose, and the viscosity enhancer accounts for 0.5 wt.% to 1.0 wt.% in the adhesive;

[0025] Step 1.2) Weighing and mixing an igniter raw material and a combustion agent to prepare an energetic alloy powder having a mass ratio of the igniter raw material to the combustion agent of 1:(0.1-0.5);

[0026] Step 1.3) The adhesive and the energetic alloy powder are mixed uniformly to obtain an alloy slurry having a solid content of 50 wt.% to 80 wt.%, where the solid content refers to the mass ratio of the energetic alloy powder to the alloy slurry.

[0027] Furthermore, in step 1.2), the ignition agent raw material is nickel-aluminum alloy or iron-aluminum alloy powder with a particle size of ≤90μm, of which aluminum accounts for 30wt.%-60wt.%; the combustion agent includes alloy powder composed of one or more of magnesium, zinc, titanium, and boron with a particle size of ≤90μm, and the impurity content is less than 20% of the total mass.

[0028] Furthermore, in step 3), the strong alkali solution is a 20 wt.% to 40 wt.% NaOH solution, the activation time is 10 min to 30 min, and the activation temperature is 50°C to 100°C; the vacuum drying temperature is 150°C to 300°C, and the drying time is 0.5 h to 3.0 h. The strong alkali solution may also be potassium hydroxide or other strong alkali solutions.

[0029] Furthermore, in step 1.1), the silicate is sodium silicate, the viscosity enhancer is sodium tripolyphosphate, the proportion of sodium tripolyphosphate in the adhesive is 1.0 wt.%, and a 25 wt.% sodium silicate aqueous solution is prepared;

[0030] In step 1.2), the igniter raw material is an iron-aluminum alloy, wherein the mass proportion of aluminum is 50 wt.%, the combustion agent is magnesium, and the mass ratio of the igniter raw material to the combustion agent is 1:0.25;

[0031] In step 1.3), the solid content is 60 wt.%;

[0032] In step 2.2), the inert atmosphere is nitrogen atmosphere, the calcination temperature is 600° C., and the calcination time is 30 min;

[0033] In step 3), the mass concentration of the NaOH solution is 30%, the activation time is 20 minutes, the inert atmosphere is nitrogen or helium, and the oxygen content and water content in the inert atmosphere glove box are not more than 100 ppm. Among them, the NaOH solution concentration, activation time, and activation temperature cooperate with each other to carry out the activation reaction, which can achieve a good activation effect. If the NaOH solution concentration is too high, the activation temperature is too high, or the activation time is too long, it will lead to excessive activation reaction, causing the ignition agent and the combustion agent to fall off; if the NaOH solution concentration is small, the activation time is short, and / or the temperature is low, the activation reaction is insufficient, the ignition agent generated by activation may be insufficient, and the ignition effect cannot meet the requirements.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The combustible foil prepared by the present invention innovatively proposes the inventive concept of a two-component system of "igniter" and "combustion agent", which enables it to quickly oxidize and release heat to spontaneously combust when exposed to air, meeting the requirement of rapid ignition of infrared bait materials.

[0036] 2. The combustion agent of the present invention introduces energetic metal powder, so that the prepared combustible foil has good combustion and ignition characteristics, can provide relatively ideal infrared radiation energy, and has only slight sparks or no sparks during the combustion process, which meets the requirements of cold light combustion.

[0037] 3. The present invention makes full use of the alloy components of the ignition agent raw materials, which are activated by a strong alkaline solution. The porous nickel or porous iron formed has a rapid reaction ability. By matching the ignition agent and the combustion agent prepared in a specific proportion, it can not only quickly ignite, but also ensure the duration and temperature of combustion.

[0038] 4. The present invention fully utilizes the promoting effect of the viscosity enhancer in the adhesive, so that the adhesion between the energetic metal powder and the prepared combustible foil is strong and the durability is excellent.

[0039] 5. The preparation method of the present invention utilizes a relatively simple coating activation method, which is highly operable, practical, and has excellent results, promising broad application prospects. The adhesive and energetic alloy powder are mixed, coated on a metal foil, and then activated to produce an ignition agent. Therefore, the processing steps prior to activation do not contain flammable materials, making the process safe and environmentally friendly.

[0040] 6. In the present invention, the particle size of the ignition agent raw material and the combustion agent is further limited, and the preferred particle size range is less than or equal to 90 μm, so as to further increase the combustion speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG1 is a process flow chart of the present invention;

[0042] FIG2 is a particle size distribution curve of the iron-aluminum alloy as the ignition raw material in Examples 1-4 of the present invention;

[0043] FIG3 is a graph showing the ignition-combustion performance of the combustible foils in Examples 1-4 of the present invention;

[0044] FIG4 is an ignition-combustion performance curve of the combustible foil in Example 1 of the present invention and Comparative Examples 1-2;

[0045] FIG5 is a SEM image of the combustible foil in Example 1 of the present invention;

[0046] FIG6 is an XRD diagram of the iron-aluminum alloy used as the ignition agent raw material for the combustible foil in Example 1 of the present invention. DETAILED DESCRIPTION

[0047] Example 1

[0048] The present invention provides a method for preparing a combustible foil for a surface-source infrared jamming flare. The process flow is shown in FIG1 and comprises the following steps:

[0049] Step 1) preparing alloy slurry of key materials for combustible foil.

[0050] Step 1.1) Prepare an adhesive by mixing sodium silicate, sodium tripolyphosphate, and water in a mass ratio of 25:1:74 and heating and stirring to dissolve to prepare an adhesive with a sodium silicate concentration of 25 wt.%; the modulus of the sodium silicate is 2.5;

[0051] Step 1.2) preparing energetic alloy powder: weighing iron-aluminum alloy powder and magnesium powder, and physically mixing them in a mass ratio of 1:0.25 to obtain energetic alloy powder, wherein the mass proportion of aluminum in the iron-aluminum alloy is 50 wt.%, the impurity content of the magnesium powder is less than 20%, and the particle size range of the iron-aluminum alloy powder and the magnesium powder is 0-30 μm;

[0052] In step 1.3), the adhesive obtained in step 1.1) and the energetic alloy powder obtained in step 1.2) are mixed using a simple solid-liquid mixing method to a solid content of 60 wt.%, and mechanically stirred to obtain an alloy slurry. The solid content refers to the mass ratio of the energetic alloy powder to the alloy slurry.

[0053] Step 2) The alloy slurry obtained in step 1) is evenly coated on the surface of the metal foil, dried in hot air and then cut, and then baked at 600° C. for 30 minutes under nitrogen atmosphere, and then naturally cooled to room temperature for use.

[0054] Metal foil needs to be pretreated before use, which includes cleaning, degreasing and drying.

[0055] The drying temperature of the hot air drying is not more than 60° C., and the drying time is not more than 1 hour. The higher the temperature, the shorter the drying time, so as to avoid the alloy slurry being too dry and difficult to cut.

[0056] In other embodiments of the present invention, the alloy slurry may also be dried at room temperature to remove moisture, and there is no time limit for room temperature drying.

[0057] Step 3) The calcined foil obtained in step 2) was activated by immersing it in a 30% NaOH solution at 80°C for 20 minutes. After activation, it was removed, rinsed with water, and dried in a vacuum oven at 200°C for 2 hours. This yielded a combustible foil for infrared jammers, designated A1. The combustible foil was stored in an inert atmosphere glove box to prevent spontaneous combustion and facilitate subsequent assembly. Figure 5 shows a SEM image of A1.

[0058] The inert atmosphere is nitrogen or helium, and the oxygen content and water content in the glove box are not greater than 100 ppm.

[0059] Example 2

[0060] Step 1) preparing alloy slurry for combustible foil.

[0061] Step 1.1) preparing an adhesive by mixing sodium silicate, sodium tripolyphosphate, and water in a mass ratio of 25:1:74 and heating and stirring to dissolve, to prepare an adhesive with a sodium silicate concentration of 25 wt.%, and a modulus of 2.5;

[0062] Step 1.2) preparing energetic alloy powder: weighing iron-aluminum alloy powder and magnesium powder, and physically mixing them in a mass ratio of 1:0.25 to obtain energetic alloy powder, wherein the mass proportion of aluminum in the iron-aluminum alloy is 50 wt.%, and the particle size range of the iron-aluminum alloy powder and the magnesium powder is 0-60 μm;

[0063] In step 1.3), a simple solid-liquid mixing method is used to mix the adhesive obtained in step 1.1) and the energetic alloy powder obtained in step 1.2) at a solid content of 60 wt.%, and the mixture is uniformly mixed by mechanical stirring to obtain an alloy slurry.

[0064] Step 2) The alloy slurry obtained in step 1) is evenly coated on the surface of the metal foil, dried in hot air and then cut, and then baked at 600° C. for 30 minutes under nitrogen atmosphere, and then naturally cooled to room temperature for use.

[0065] Step 3) The calcined foil obtained in step 2) was immersed in a 30% NaOH solution and activated at 80°C for 20 minutes. After activation, it was removed, washed with water, and dried in a vacuum oven at 200°C for 2.0 hours to obtain the combustible foil A2 for infrared jammers. The combustible foil was stored in an inert atmosphere glove box.

[0066] Example 3

[0067] Step 1) preparing alloy slurry for combustible foil.

[0068] Step 1.1) preparing an adhesive by mixing sodium silicate, sodium tripolyphosphate, and water in a mass ratio of 25:1:74 and heating and stirring to dissolve, to prepare an adhesive with a sodium silicate concentration of 25 wt.%, and a modulus of 2.5;

[0069] Step 1.2) preparing energetic alloy powder: weighing iron-aluminum alloy powder and magnesium powder, and physically mixing them in a mass ratio of 1:0.25 to obtain energetic alloy powder, wherein the mass proportion of aluminum in the iron-aluminum alloy is 50 wt.%, and the particle size range of the iron-aluminum alloy powder and the magnesium powder is 0-90 μm;

[0070] In step 1.3), a simple solid-liquid mixing method is used to mix the adhesive obtained in step 1.1) and the energetic alloy powder obtained in step 1.2) at a solid content of 60 wt.%, and the mixture is uniformly mixed by mechanical stirring to obtain an alloy slurry.

[0071] Step 2) The alloy slurry obtained in step 1) is evenly coated on the surface of the metal foil, dried in hot air and then cut, and then baked at 600° C. for 30 minutes under nitrogen atmosphere, and then naturally cooled to room temperature for use.

[0072] Step 3) The calcined foil obtained in step 2) was immersed in a 30% NaOH solution and activated at 80°C for 20 minutes. After activation, it was removed, rinsed with water, and dried in a vacuum oven at 200°C for 2.0 hours to obtain a combustible foil A3 for infrared jammers. The combustible foil was stored in an inert atmosphere glove box.

[0073] Example 4

[0074] Step 1) preparing alloy slurry for combustible foil.

[0075] Step 1.1) preparing an adhesive by mixing sodium silicate, sodium tripolyphosphate, and water in a mass ratio of 25:1:74 and heating and stirring to dissolve, to prepare an adhesive with a sodium silicate concentration of 25 wt.%, and a modulus of 2.5;

[0076] Step 1.2) preparing energetic alloy powder: weighing iron-aluminum alloy powder and magnesium powder, and physically mixing them in a mass ratio of 1:0.25 to obtain energetic alloy powder, wherein the mass proportion of aluminum in the iron-aluminum alloy is 50 wt.%, and the particle size range of the iron-aluminum alloy powder and the magnesium powder is 0-120 μm;

[0077] In step 1.3), a simple solid-liquid mixing method is used to mix the adhesive obtained in step 1.1) and the energetic alloy powder obtained in step 1.2) at a solid content of 60 wt.%, and the mixture is uniformly mixed by mechanical stirring to obtain an alloy slurry.

[0078] Step 2) The alloy slurry obtained in step 1) is evenly coated on the surface of the metal foil, dried in hot air and then cut, and then baked at 600° C. for 30 minutes under nitrogen atmosphere, and then naturally cooled to room temperature for use.

[0079] Step 3) The calcined foil obtained in step 2) was immersed in a 30% NaOH solution and activated at 80°C for 20 minutes. After activation, the foil was removed, rinsed with water, and dried in a vacuum oven at 200°C for 2.0 hours to obtain a combustible foil A4 for infrared jammers. The combustible foil was stored in an inert atmosphere glove box.

[0080] Example 5

[0081] Step 1) preparing alloy slurry for combustible foil.

[0082] In step 1.1), an adhesive was prepared by mixing sodium silicate, polyvinyl alcohol, and water in a mass ratio of 20:0.75:79.25 and heating and stirring to dissolve the mixture to prepare an adhesive having a sodium silicate concentration of 20 wt.% and a modulus of 2.0.

[0083] Step 1.2) preparing energetic alloy powder: weighing nickel-aluminum alloy powder and zinc powder, and physically mixing them in a mass ratio of 1:0.1 to obtain energetic alloy powder, wherein the mass proportion of aluminum in the nickel-aluminum alloy is 30 wt.%, and the particle size range of the nickel-aluminum alloy powder and the zinc powder is 0-60 μm;

[0084] In step 1.3), the adhesive obtained in step 1.1) and the energetic alloy powder obtained in step 1.2) are mixed at a solid content of 50 wt.% by a simple solid-liquid mixing method, and the mixture is uniformly mixed by mechanical stirring to obtain an alloy slurry.

[0085] Step 2) The alloy slurry obtained in step 1) is evenly coated on the surface of the metal foil, dried in hot air and then cut, and then baked at 400°C for 60 minutes under nitrogen atmosphere, and then naturally cooled to room temperature for use.

[0086] Step 3) The calcined foil obtained in step 2) was immersed in a 20% NaOH solution at 50°C for 30 minutes for activation. After activation, it was removed, rinsed with water, and dried in a vacuum oven at 150°C for 3.0 hours to obtain the combustible foil A5 for infrared jammers. The combustible foil was stored in an inert atmosphere glove box.

[0087] Example 6

[0088] Step 1) preparing alloy slurry for combustible foil.

[0089] In step 1.1), an adhesive was prepared by mixing potassium silicate, hydroxyethyl cellulose, methyl cellulose, and water in a mass ratio of 30:0.5:0.5:69 and heating and stirring to dissolve the mixture to prepare an adhesive having a potassium silicate concentration of 30 wt.% and a modulus of 3.4.

[0090] Step 1.2) preparing energetic alloy powder: weighing iron-aluminum alloy powder and titanium powder, and physically mixing them in a mass ratio of 1:0.5 to obtain energetic alloy powder, wherein the mass proportion of aluminum in the iron-aluminum alloy is 60 wt.%, and the particle size range of the iron-aluminum alloy powder and the titanium powder is 0-60 μm;

[0091] In step 1.3), a simple solid-liquid mixing method is used to mix the adhesive obtained in step 1.1) and the energetic alloy powder obtained in step 1.2) at a solid content of 80 wt.%, and the mixture is uniformly mixed by mechanical stirring to obtain an alloy slurry.

[0092] Step 2) The alloy slurry obtained in step 1) is evenly coated on the surface of the metal foil, dried in hot air and then cut, and then baked at 700°C for 10 minutes under nitrogen atmosphere, and then naturally cooled to room temperature for use.

[0093] Step 3) The calcined foil obtained in step 2) was immersed in a 40% NaOH solution at 100°C for activation for 10 minutes. After activation, the foil was removed, rinsed with water, and dried in a vacuum oven at 300°C for 0.5 hours to obtain a combustible foil A6 for infrared jammers. The combustible foil was stored in an inert atmosphere glove box.

[0094] Comparative Example 1

[0095] The steps of Comparative Example 1 are basically the same as those of Example 1, except that the energetic alloy slurry in Comparative Example 1 contains only the ignition raw material Fe-Al alloy and no combustion agent component, thereby obtaining a combustible foil B1.

[0096] Comparative Example 2

[0097] The steps of Comparative Example 2 are basically the same as those of Example 1, except that the adhesive used in the energetic alloy slurry in Comparative Example 2 is pure sodium silicate solution without a bonding enhancer component, and a combustible foil B2 is obtained.

[0098] Combustion Performance Testing: The ignition and combustion characteristics of the combustible foil were tested using a PS400 Guide infrared thermal imager. Specifically, the combustible foil was removed from the glove box. Upon contact with air, the foil rapidly ignited and burned, emitting intense light and heat. A camera was then focused on the foil to measure the temperature field, verifying the combustible foil's combustion performance. The technical specifications used in this invention require the following: ignition time ≤ 1.5 seconds (from room temperature to 900K); combustion duration ≥ 3.0 seconds (above 900K).

[0099] Adhesion performance test: The method for inspecting the powder loss during the use of flammable foil is a visual observation and acceptance method. The sample is bent in a glove box with a bending tool, and the powder loss in the gaps at the bends on both sides of the foil is visually observed. The sample is considered qualified if the foil base is not exposed.

[0100] Table 1 Comparison of ignition and combustion performance data of the combustible foil of the present invention

[0101] By comparing the performance test data of the combustible foil, it can be seen that the comprehensive performance of the two comparative examples is relatively poor. The ignition-combustion performance curve is shown in Figure 4. The combustion temperature and duration of the combustible foil of Comparative Example 1 do not meet the use index requirements. Although Comparative Example 2 has good ignition-combustion characteristics, its adhesion performance cannot meet the use requirements of the foil. The combustible foil obtained by the present invention, through a two-component system of a composite igniter and a combustion agent, wherein the igniter and the combustion agent have a specific ratio and cooperate with each other, not only solves the problem of rapid ignition of the foil when exposed to air, but also achieves the purpose of the foil being able to continuously burn and release heat at high temperature. The particle size distribution of Examples 1-4 is shown in Figure 2, and the ignition-combustion performance curve is shown in Figure 3. The porous iron igniter after NaOH activation ignites magnesium powder and then burns to emit strong infrared radiation light, and the smaller the particle size of the igniter raw material, the faster the ignition speed will be. When the particle size of the igniter raw material is too large, the crystal nuclei burn too vigorously, resulting in strong sparks during combustion, which affects the performance of the combustible foil. For example, in Example 6, the igniter raw material particle size range is 0-120 μm, and there is a small amount of sparks during combustion. Therefore, the particle size of the igniter raw material and the combustion agent is preferably 90 μm or less. Based on the above performance data, it can be seen that the combustible foil of Example 1 has the best performance, with a longer duration and maximum temperature after combustion, and a shorter ignition time.

[0102] At the same time, in the embodiments of the present invention, the adhesion performance of the combustible foils obtained in Examples 1-6 and Comparative Example 1 all meet the use requirements, while Comparative Example 2 suffers from powder shedding. This is mainly due to the introduction of a viscosity enhancer into the adhesive used in the present invention. The introduction of the viscosity enhancer can effectively improve the bonding ability of the adhesive, so that the powder shedding of the combustible foil after loading can meet the use requirements of environmental adaptability such as vibration.

Claims

1. A combustible foil for a surface source type infrared decoy flare, characterized in that: it includes a metal foil and a mixture coated on the surface of the metal foil, and the mixture includes an adhesive, an ignition agent and a combustion agent; the adhesive includes silicate; the ignition agent is a material that can spontaneously combust in air.

2. The combustible foil for a surface source type infrared decoy flare according to claim 1, characterized in that: the ignition agent is formed by activating nickel-aluminum alloy or iron-aluminum alloy through a strong alkali solution, and the aluminum content in the nickel-aluminum alloy or iron-aluminum alloy is 30wt.% - 60wt.%; the mass ratio of the nickel-aluminum alloy / iron-aluminum alloy to the combustion agent is 1:(0.1 - 0.5).

3. The combustible foil for a surface source type infrared decoy flare according to claim 1 or 2, characterized in that: the adhesive further includes a viscosity enhancer, and the viscosity enhancer is one or more of sodium tripolyphosphate, polyvinyl alcohol, hydroxyethyl cellulose, and methyl cellulose; the silicate is sodium silicate and / or potassium silicate, and its modulus is 2.0 - 3.4; the combustion agent includes an alloy powder composed of one or more of magnesium, zinc, titanium, and boron, and the impurity content is less than 20% of the total mass.

4. The combustible foil for a surface source type infrared decoy flare according to claim 3, characterized in that: the ignition agent is formed by activating iron-aluminum alloy through NaOH solution, and the combustion agent is magnesium; the adhesive is sodium silicate, and the viscosity enhancer is sodium tripolyphosphate.

5. A preparation method of a combustible foil for a surface source type infrared decoy flare, characterized in that, it includes the following steps: Step 1) Prepare an alloy slurry Mix the adhesive and the energetic alloy powder evenly to obtain an alloy slurry; the adhesive is an aqueous solution of silicate, and the energetic alloy powder includes an ignition agent raw material and a combustion agent; Step 2) Coating and roasting Step 2.1) Uniformly coat the energetic slurry obtained in Step 1 on the surface of the metal foil, and dry to remove the moisture of the energetic slurry; Step 2.2) Roast the metal foil under an inert atmosphere condition, and cool it to room temperature for standby; Step 3) Immerse the metal foil obtained in Step 2 in a strong alkali solution to activate the ignition agent raw material to form an ignition agent. After activation, take it out, wash it with water and perform vacuum drying to obtain a combustible foil, and store the combustible foil in an inert atmosphere glove box.

6. The preparation method of a combustible foil for a surface source type infrared decoy flare according to claim 5, characterized in that: in Step 2.1), the drying temperature ≤ 60°C, and the drying time ≤ 1h; after drying, it also includes cutting the metal foil according to different requirements; in Step 2.2), the roasting temperature is 400°C - 700°C, the roasting time is 10min - 60min, and the roasting atmosphere is nitrogen.

7. The preparation method of a combustible foil for a surface source type infrared decoy flare according to claim 5 or 6, characterized in that: Step 1) is specifically: Step 1.1) Dissolve the silicate, or the silicate and the viscosity enhancer in water to prepare an aqueous solution of silicate with a mass concentration of 20wt.% - 30wt.% as the adhesive; the silicate is one or two of sodium silicate or potassium silicate, and the modulus of sodium silicate or potassium silicate is 2.0 - 3.4; The viscosity enhancer is one or more of sodium tripolyphosphate, polyvinyl alcohol, hydroxyethyl cellulose, and methyl cellulose, and the proportion of the viscosity enhancer in the adhesive is 0.5 wt.% - 1.0 wt.%; Step 1.2) Weigh the ignition agent raw materials and the combustion agent and mix them to prepare an energetic alloy powder with a mass ratio of the ignition agent raw materials to the combustion agent of 1: (0.1 - 0.5); Step 1.3) Mix the adhesive and the energetic alloy powder evenly to obtain an alloy slurry with a solid content of 50 wt.% - 80 wt.%. The solid content refers to the mass ratio of the energetic alloy powder in the alloy slurry.

8. The preparation method of the combustible foil for a surface source type infrared decoy bomb according to claim 7, characterized in that: In step 1.2), the ignition agent raw materials are nickel-aluminum alloy or iron-aluminum alloy powder with a particle size ≤ 90 μm, and the proportion of aluminum is 30 wt.% - 60 wt.%; The combustion agent includes an alloy powder composed of one or more of magnesium, zinc, titanium, and boron, with a particle size ≤ 90 μm, and the impurity content is less than 20% of the total mass.

9. The preparation method of the combustible foil for a surface source type infrared decoy bomb according to claim 8, characterized in that: In step 3), the strong alkali solution is a 20 wt.% - 40 wt.% NaOH solution, the activation time is 10 min - 30 min, and the activation temperature is 50 °C - 100 °C; the vacuum drying temperature is 150 °C - 300 °C, and the drying time is 0.5 h - 3.0 h.

10. The preparation method of the combustible foil for a surface source type infrared decoy bomb according to claim 9, characterized in that: In step 1.1), the silicate is sodium silicate, the viscosity enhancer is sodium tripolyphosphate, and the proportion of sodium tripolyphosphate in the adhesive is 1.0 wt.%. Prepare a 25 wt.% sodium silicate aqueous solution; In step 1.2), the ignition agent raw materials are iron-aluminum alloy, and the mass proportion of aluminum is 50 wt.%, and the combustion agent is magnesium. The mass ratio of the ignition agent raw materials to the combustion agent is 1:0.25; In step 1.3), the solid content is 60 wt.%; In step 2.2), the inert atmosphere is a nitrogen atmosphere, the roasting temperature is 600 °C, and the roasting time is 30 min; In step 3), the mass concentration of the NaOH solution is 30%, the activation time is 20 min, the inert atmosphere is nitrogen or helium, and the oxygen content and water content in the inert atmosphere glove box are both not more than 100 ppm.

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