Infrared invisible aerogel and preparation method thereof

Abstract

The invention belongs to the field of infrared stealth technology, and discloses an infrared stealth aerogel and a preparation method thereof. The aerogel has a three-dimensional network porous structure, and the three-dimensional network porous structure is formed by three-dimensionally building nanosheet layers. The infrared stealth aerogel and the preparation method thereof can achieve, through the cooperation of a speed change mechanism, a collection unit, an analysis and processing unit and a control unit, that when the uniform dispersion degree of iron oxide nanoparticles and carbon nanotubes in a third mixture solution does not meet the standard, the control unit forms a control instruction; according to a proportional coefficient, the rotation speed of an intermittent Y-axis forward and reverse stirring mechanism and an X-axis stirring mechanism is proportionally increased through the extension and contraction action of cylinders located on both sides of the interior of a synchronous toothed belt, thereby achieving the effect of uniformly dispersing the iron oxide nanoparticles and carbon nanotubes in the third mixture solution. This precise control helps to ensure the quality of the prepared aerogel product and give full play to its infrared stealth performance.

Description

Technical Field

[0001] The invention belongs to the technical field of infrared stealth, and in particular is an infrared stealth aerogel and a preparation method thereof. Background Art

[0002] All objects with a temperature above absolute zero will emit infrared signals (0.78~1000μm), but most infrared signals will be scattered and absorbed by particles, water vapor or carbon dioxide molecules in the air. Only near-infrared (NIR: 0.78~2.5μm), mid-infrared (MIR: 3~5μm) and far-infrared (FIR: 8~14μm) signals can penetrate the atmosphere and be detected. Infrared stealth technology changes the radiation characteristics of the surface of the object so that the infrared radiation emitted by the surface of the object being measured is as similar as possible to the surrounding background radiation, so that the infrared detection sensor cannot distinguish the target.

[0003] According to the Stefan-Boltzmann law, an effective way to avoid infrared detection and tracking is to reduce the infrared emissivity and surface temperature of the object surface, and reducing the surface temperature is more effective. However, existing stealth materials have the disadvantages of high density, great environmental impact, low mechanical properties, and disadvantages of being not compatible with radar stealth effects. Aerogel is an ultra-light solid material filled with gaseous dispersion medium in a nano-scale porous structure. The large amount of air contained in its porous structure has a lower thermal conductivity than the solid skeleton, and its high porosity greatly reduces the thermal conduction intensity and thermal radiation in the solid phase, thereby showing a good insulation effect and inhibiting its thermal infrared characteristics. However, most of the existing aerogels are prepared using toxic and hazardous substances, which cause harm to the environment to a certain extent. Therefore, it is extremely important to develop environmentally friendly aerogels. At the same time, since the stirring equipment used in the preparation of existing aerogels lacks the function of detecting the uniformity of stirring various raw materials, it is impossible to adjust the stirring parameters in time, resulting in poor quality of the aerogel products prepared subsequently and unsatisfactory infrared stealth function.

[0004] Based on this, the present invention proposes an infrared invisible aerogel and a preparation method thereof. Summary of the invention

[0005] In order to solve the problems raised in the above-mentioned background technology, the present invention provides an infrared invisible aerogel and a preparation method thereof, which has the advantages of solving the problems that most of the existing aerogels are prepared using toxic and harmful substances, causing harm to the environment to a certain extent, and the stirring equipment used in the preparation of the existing aerogels lacks the function of detecting the uniformity of stirring of various raw materials, making it impossible to adjust the stirring parameters in time, resulting in poor quality of the subsequently prepared aerogel products and unsatisfactory infrared stealth function.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: an infrared invisible aerogel, the aerogel having a three-dimensional network porous structure, the three-dimensional network porous structure is formed by three-dimensional construction of nanosheet layers, and the raw materials of the nanosheet layers include the following selected materials, such as polyvinyl alcohol, sodium alginate, chitosan, silica powder, iron oxide nanoparticles, carbon nanotubes, n-butanol and silane coupling agent.

[0007] Preferably, the mass percentage content of each component is: polyvinyl alcohol 45%-60%, sodium alginate 5%-15%, chitosan 5%-10%, silicon dioxide powder 5%-8%, iron oxide nanoparticles 1%-10%, carbon nanotubes 10%-15%, n-butanol 5%-10% and silane coupling agent 1%-3%.

[0008] Preferably, a method for preparing infrared invisible aerogel is provided, and the specific preparation method is as follows: step 1, first add an appropriate amount of deionized water into a stirring device and heat it at a heating temperature of 50-80°C, then add raw materials with a weight ratio of 45%-60% polyvinyl alcohol, 5%-15% sodium alginate, and 5%-10% chitosan into the stirring device and mix with deionized water and stir until they are completely dissolved, and finally form a uniform first mixture solution in the stirring device, and stir the stirring device at a temperature range of 60-70°C for 10-25 minutes, and the speed range of the stirring device is 3000-4000 rpm;

[0009] Step 2: Under the condition of heating temperature of 60-70° C., 5%-10% of n-butanol by weight is added to the first mixture solution and stirred evenly to form a second mixture solution; the stirring time is 5-10 minutes, and the speed range of the stirring device is 2000-2500 rpm;

[0010] Step 3, gradually adding 5%-8% of silicon dioxide powder, 1%-10% of iron oxide nanoparticles, 10%-15% of carbon nanotubes and 1%-3% of silane coupling agent by weight to the second mixture solution and stirring evenly to form a third mixture solution, wherein the initial speed of the stirring device is 400 rpm, and the stirring time is 0.3-2 hours. After the stirring is completed, the stirring device obtains and analyzes the dispersion image of the iron oxide nanoparticles and carbon nanotubes in the third mixture solution through the microscope camera inside the stirring device. Based on the analysis results, if it is analyzed that the iron oxide nanoparticles and carbon nanotubes are unevenly dispersed in the third mixture solution, the ratio of the stirring device speed is adjusted to correspond to the ratio of the corresponding evaluation threshold of the analysis result, otherwise, proceed to the next step;

[0011] Step 4: Pour the third mixture solution into a mold, and then place the mold containing the third mixture solution in a freezer for 50-60 hours at a freezing temperature of -50 to -80°C. During the freezing process, the water in the third mixture solution will gradually solidify into ice crystals. After freezing, place the sample in a vacuum and dry it. The vacuum degree range is 10 -3 -10 -6 Pa, and the drying time is 85-100 hours to obtain aerogel.

[0012] Preferably, the stirring device in step 1 includes a support frame, a stirring tank, a speed change mechanism, an intermittent Y-axis forward and reverse stirring mechanism, and an X-axis stirring mechanism;

[0013] A speed change mechanism, the speed change mechanism is located above the mixing tank, and the speed change mechanism includes a synchronous toothed belt, a cylinder and meshing teeth. After the cylinder telescopically drives the meshing teeth to engage with the synchronous toothed belt, the cylinder located on both sides of the synchronous toothed belt can be extended and retracted to realize online stepless speed change of the rotation speed of the intermittent Y-axis forward and reverse mixing mechanism and the X-axis mixing mechanism;

[0014] An intermittent Y-axis forward and reverse stirring mechanism, wherein the intermittent Y-axis forward and reverse stirring mechanism is located between the stirring tank and the speed change mechanism, and comprises a first external gear, a second external gear, a first gear, a second gear, a third gear and an arc-shaped stirring blade, wherein the third gear is located between the first gear and the second gear, and the speed change mechanism drives the first external gear and the second external gear to achieve external meshing while the speed change mechanism moves. At this time, the first gear, the second gear and the third gear are driven to mesh by utilizing the characteristic that the external meshing of the first external gear and the second external gear rotates in opposite directions, thereby driving the arc-shaped stirring blade to achieve intermittent Y-axis forward and reverse stirring action on the raw materials of the nanosheet layer in the stirring tank;

[0015] An X-axis stirring mechanism, the X-axis stirring mechanism is located inside the stirring tank, the X-axis stirring mechanism includes a bevel gear set and a spiral blade, and when the speed change mechanism moves, adjacent bevel gears in the bevel gear set are driven to mesh with each other, driving the spiral blade to stir the raw materials of the nanosheet layer in the stirring tank in the X-axis direction;

[0016] It also includes a collection unit, an analysis and processing unit and a control unit, wherein:

[0017] When a third mixture solution is formed in the stirring device, the collection unit collects images of the dispersion of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution, and sends the data to the analysis and processing unit, which uses edge detection to distinguish the dispersed area and the aggregated area of ​​the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution, thereby obtaining an image analysis result of the dispersion of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution, and based on the image analysis result, calculates the coverage area percentage of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution, and evaluates the uniform dispersion degree of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution according to the coverage area percentage;

[0018] When the coverage area percentage is less than a preset threshold, the coverage area percentage is determined to be less than the preset threshold ratio, a proportional coefficient is formed, and a control instruction is formed by the control unit; according to the proportional coefficient, the speed change mechanism of the stirring device increases the rotation speed of the intermittent Y-axis forward and reverse stirring mechanism and the X-axis stirring mechanism in equal proportion until the coverage area percentage is greater than or equal to the preset threshold;

[0019] When the coverage area percentage is greater than or equal to the preset threshold, proceed to the next step.

[0020] Preferably, the microscope camera is fixedly mounted on the inner top wall of the stirring tank, the inner wall of the support frame is fixedly sleeved with the outer surface of the stirring tank, a temperature sensor is fixedly mounted on the outer surface of the stirring tank, the detection end of the temperature sensor passes through the stirring tank and extends to the interior of the stirring tank, the speed change mechanism also includes a driving motor fixedly mounted on the right outer surface of the stirring tank, the output shaft of the driving motor is fixedly mounted with a transmission shaft through a coupling, the upper surface of the stirring tank is respectively rotatably sleeved with a first connecting shaft and a second connecting shaft, and the first connecting shaft and the second connecting shaft are symmetrically distributed on the upper surface of the stirring tank with the axis of the stirring tank as the center of symmetry, one end of the second connecting shaft and the transmission shaft are fixedly sleeved with a speed change disk, the cylinder is fixedly mounted on the radial direction of the outer surface of the speed change disk, and the meshing teeth are fixedly mounted on the outer end of the piston rod of the cylinder to achieve radial telescopic expansion and contraction.

[0021] Preferably, the intermittent Y-axis forward and reverse stirring mechanism also includes a stirring shaft rotatably sleeved at the center of the upper surface of the stirring tank, the first external gear is fixedly sleeved on the outer surface of the first connecting shaft, the second external gear is fixedly sleeved on the outer surface of the second connecting shaft, the first gear is fixedly sleeved on the outer surface of the first connecting shaft below the first external gear, the second gear is fixedly sleeved on the outer surface of the second connecting shaft below the second external gear, the third gear is fixedly sleeved on one end of the stirring shaft above the stirring tank, and the arc-shaped stirring blades are fixedly mounted in a ring array on the outer surface of the stirring shaft inside the stirring tank.

[0022] Preferably, the X-axis stirring mechanism also includes a transmission cavity opened inside the stirring shaft, the inner top wall of the transmission cavity is rotatably sleeved with a core shaft, the top end of the core shaft passes through the transmission cavity and extends to the top of the stirring shaft, and the outer surface of the core shaft located above the stirring shaft is rotatably sleeved with a fixing frame.

[0023] Preferably, the lower surface of the fixed frame is fixedly connected to the upper surface of the mixing tank, the outer surface of the core shaft located above the fixed frame is fixedly sleeved with a fourth gear, the outer surface of the second connecting shaft located between the first outer gear and the second gear is fixedly sleeved with a fifth gear, and the fourth gear is meshed with the fifth gear.

[0024] Preferably, the outer surface of each bevel gear in the bevel gear set is rotatably sleeved with the inner wall of the transmission chamber, the bottom end of the core shaft is fixedly sleeved with the inner wall of one of the bevel gears in the bevel gear set, and the inner walls of eight of the bevel gears in the bevel gear set are fixedly sleeved with a rotating shaft, one end of the rotating shaft passes through the transmission chamber and the stirring shaft and extends to the interior of the stirring tank, the spiral blade is fixedly installed on the outer surface of the rotating stirring tank, the lower surface of the stirring tank is fixedly connected to a discharge pipe with a solenoid valve, the upper surface of the stirring tank is respectively provided with a first inlet and a second inlet, and a heating pipe is fixedly installed on the inner bottom wall of the stirring tank, and one end of the heating pipe passes through the stirring tank and extends to the outside of the stirring tank.

[0025] Preferably, the calculation formula for the coverage area percentage is:

[0026]

[0027] Wherein, D represents the coverage area percentage of iron oxide nanoparticles and carbon nanotubes in the third mixture solution, X represents the number of pixels covered by iron oxide nanoparticles and carbon nanotubes in the image analysis result, and O represents the total number of pixels of the entire image in the image analysis result.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention can achieve the effect of uniformly dispersing the iron oxide nanoparticles and carbon nanotubes in the third mixture solution when the uniform dispersion of the iron oxide nanoparticles and carbon nanotubes in the third mixture solution does not meet the standard through the cooperation of the speed change mechanism, the collection unit, the analysis and processing unit and the control unit. The control unit generates a control instruction; according to the proportional coefficient, the cylinders located on both sides of the synchronous toothed belt extend and contract to increase the rotation speed of the intermittent Y-axis forward and reverse stirring mechanism and the X-axis stirring mechanism in proportion, thereby achieving the effect of uniformly dispersing the iron oxide nanoparticles and carbon nanotubes in the third mixture solution. This precise control helps to ensure the quality of the prepared aerogel product and give full play to its infrared stealth performance.

[0030] 2. The present invention can achieve multi-directional stirring of the liquid in the stirring tank through the cooperation of the intermittent Y-axis forward and reverse stirring mechanism and the X-axis stirring mechanism, so that the liquid can be stirred more evenly. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of the present invention;

[0032] Figure 2 A stereoscopic diagram of the structure of the microscopic camera of the present invention;

[0033] Figure 3 This is a three-dimensional diagram of the arc-shaped stirring blade structure of the present invention;

[0034] Figure 4 It is a three-dimensional diagram of the overall structure of the speed change mechanism of the present invention;

[0035] Figure 5 This is an exploded view of the intermittent Y-axis forward and reverse stirring mechanism of the present invention;

[0036] Figure 6 It is a schematic diagram of the working process of the stirring equipment of the present invention.

[0037] In the figure: 1. support frame; 2. stirring tank; 3. synchronous belt; 31. cylinder; 32. meshing teeth; 33. driving motor; 34. transmission shaft; 35. first connecting shaft; 36. second connecting shaft; 37. speed change plate; 4. first external gear; 41. second external gear; 42. first gear; 43. second gear; 44. third gear; 45. arc stirring fan blade; 46. stirring shaft; 5. bevel gear set; 51. spiral blade; 52. transmission chamber; 53. core shaft; 54. fixing frame; 55. fourth gear; 56. fifth gear; 57. rotating shaft; 58. discharge pipe; 59. first inlet; 510. second inlet; 511. heating pipe; 6. acquisition unit; 61. microscope camera; 7. analysis and processing unit; 8. control unit; 9. temperature sensor. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] like Figures 1 to 6As shown, the present invention provides an infrared invisible aerogel, the aerogel has a three-dimensional network porous structure, the three-dimensional network porous structure is formed by three-dimensional construction of nanosheet layers, the raw materials of the nanosheet layers include the following selected materials, such as polyvinyl alcohol, sodium alginate, chitosan, silicon dioxide powder, iron oxide nanoparticles, carbon nanotubes, iron oxide nanoparticles and carbon nanotubes are added to the raw materials for preparing the aerogel, which can effectively absorb infrared light and improve the infrared stealth performance of the aerogel, n-butanol and a silane coupling agent.

[0040] The mass percentage content of each component is: polyvinyl alcohol 45%-60%, sodium alginate 5%-15%, chitosan 5%-10%, silicon dioxide powder 5%-8%, iron oxide nanoparticles 1%-10%, carbon nanotubes 10%-15%, n-butanol 5%-10% and silane coupling agent 1%-3%.

[0041] In this embodiment, the preparation method of infrared invisible aerogel is:

[0042] Step 1, first add an appropriate amount of deionized water into a stirring device for heating, the appropriate amount of water refers to an amount of water sufficient to dissolve all soluble components, the heating temperature is 50-80°C, then, select raw materials with a weight ratio of 45%-60% polyvinyl alcohol, 5%-15% sodium alginate, and 5%-10% chitosan, add them into the stirring device and mix with the deionized water until they are completely dissolved, and finally form a uniform first mixture solution in the stirring device, and stir the stirring device at a temperature range of 60-70°C for 10-25 minutes, and the speed range of the stirring device is 3000-4000 rpm;

[0043] Step 2: Under the condition of heating temperature of 60-70° C., 5%-10% of n-butanol by weight is added to the first mixture solution and stirred evenly to form a second mixture solution; the stirring time is 5-10 minutes, and the speed range of the stirring device is 2000-2500 rpm;

[0044] Step 3: gradually add 5%-8% of silicon dioxide powder, 1%-10% of iron oxide nanoparticles, 10%-15% of carbon nanotubes and 1%-3% of silane coupling agent by weight to the second mixture solution and stir evenly to form a third mixture solution, wherein the initial speed of the stirring device is 400 rpm and the stirring time is 0.3-2 hours. After the stirring is completed, the stirring device obtains and analyzes the dispersion image of the iron oxide nanoparticles and carbon nanotubes in the third mixture solution through the microscope camera 61 inside the stirring device. Based on the analysis result, if it is analyzed that the iron oxide nanoparticles and carbon nanotubes are unevenly dispersed or aggregated in the third mixture solution, the ratio of the stirring device speed is adjusted to correspond to the ratio of the corresponding evaluation threshold of the analysis result. Otherwise, the next step is entered. This operation is to increase the contact opportunity between the iron oxide nanoparticles and carbon nanotubes and the second mixture solution to promote more uniform dispersion.

[0045] Step 4: Pour the third mixture solution into a mold to form a desired shape and size, and then place the mold containing the third mixture solution in a freezer for 50-60 hours at a temperature of -50 to -80°C. During the freezing process, the water in the third mixture solution will gradually solidify into ice crystals. After freezing, place the sample in a vacuum and dry it. The vacuum degree range is 10 -3 -10 -6 Pa, the drying time is 85-100 hours, at this time, the ice crystals will undergo a sublimation process, directly changing from solid to gas without passing through the liquid state, which can avoid the conventional melting process, reduce the damage of water to the sample, and maintain the structure and properties of the sample, that is, aerogel.

[0046] like Figures 1 to 6 As shown, in order to achieve uniform dispersion of iron oxide nanoparticles and carbon nanotubes in the third mixture solution, the stirring device in step 1 includes a support frame 1, a stirring tank 2, a speed change mechanism, an intermittent Y-axis forward and reverse stirring mechanism, and an X-axis stirring mechanism;

[0047] The speed change mechanism is located above the mixing tank 2. The speed change mechanism includes a synchronous toothed belt 3, a cylinder 31 and meshing teeth 32. After the cylinder 31 retracts and drives the meshing teeth 32 to engage with the synchronous toothed belt 3, the cylinder 31 located on both sides of the synchronous toothed belt 3 retracts and retracts to realize online stepless speed change of the intermittent Y-axis forward and reverse mixing mechanism and the X-axis mixing mechanism;

[0048] An intermittent Y-axis forward and reverse stirring mechanism, the intermittent Y-axis forward and reverse stirring mechanism is located between the stirring tank 2 and the speed change mechanism, the intermittent Y-axis forward and reverse stirring mechanism comprises a first external gear 4, a second external gear 41, a first gear 42, a second gear 43, a third gear 44 and an arc-shaped stirring blade 45, the third gear 44 is located between the first gear 42 and the second gear 43, and the speed change mechanism drives the first external gear 4 and the second external gear 41 to achieve external meshing while the speed change mechanism moves. At this time, the first gear 42, the second gear 43 and the third gear 44 are driven to mesh by utilizing the opposite direction characteristics of the external meshing of the first external gear 4 and the second external gear 41, thereby driving the arc-shaped stirring blade 45 to achieve intermittent Y-axis forward and reverse stirring action on the raw materials of the nanosheet layer in the stirring tank 2;

[0049] X-axis stirring mechanism, the X-axis stirring mechanism is located inside the stirring tank 2, and the X-axis stirring mechanism includes a bevel gear set 5 and a spiral blade 51. When the speed change mechanism moves, the adjacent bevel gears in the bevel gear set 5 are driven to mesh with each other, and the spiral blade 51 is driven to stir the raw materials of the nanosheet layer in the stirring tank 2 in the X-axis direction;

[0050] It also includes a collection unit 6, an analysis and processing unit 7 and a control unit 8, wherein:

[0051] When a third mixture solution is formed in the stirring device, the collection unit 6 collects images of the dispersion of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution, and sends the data to the analysis and processing unit 7. The analysis and processing unit 7 distinguishes the dispersion area and the aggregation area of ​​the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution by edge detection, thereby obtaining an image analysis result of the dispersion of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution. Based on the image analysis result, the coverage area percentage of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution is calculated, and the uniform dispersion degree of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution is evaluated by the coverage area percentage.

[0052] When the coverage area percentage is less than a preset threshold value, wherein the preset threshold value in the present application is 95%, it is determined that the coverage area percentage is less than the preset threshold ratio, a proportional coefficient is formed, and a control instruction is formed by the control unit 8; according to the proportional coefficient, the speed change mechanism of the stirring device increases the speed of the intermittent Y-axis forward and reverse stirring mechanism and the X-axis stirring mechanism in proportion until the coverage area percentage is greater than or equal to the preset threshold value;

[0053] When the coverage area percentage is greater than or equal to the preset threshold, proceed to the next step.

[0054] like Figure 1 , Figure 3 and Figure 4As shown, in order to accurately control the degree of uniform dispersion of iron oxide nanoparticles and carbon nanotubes in the third mixture solution, a microscope camera 61 is fixedly installed on the inner top wall of the stirring tank 2, the inner wall of the support frame 1 is fixedly sleeved with the outer surface of the stirring tank 2, a temperature sensor 9 is fixedly installed on the outer surface of the stirring tank 2, and the detection end of the temperature sensor 9 extends to the inside of the stirring tank 2 after passing through the stirring tank 2. The speed change mechanism also includes a drive motor 33 fixedly installed on the right outer surface of the stirring tank 2, and the output shaft of the drive motor 33 is fixedly installed with a transmission shaft 34 through a coupling. The upper surface of the stirring tank 2 is rotatably sleeved with a first connecting shaft 35 and a second connecting shaft 36, and the first connecting shaft 35 and the second connecting shaft 36 are symmetrically distributed on the upper surface of the stirring tank 2 with the axis of the stirring tank 2 as the symmetry center. One end of the second connecting shaft 36 and the transmission shaft 34 are fixedly sleeved with a speed change disc 37, and the cylinder 31 is fixedly installed in the radial direction of the outer surface of the speed change disc 37. The meshing teeth 32 are fixedly installed on the outer end of the piston rod of the cylinder 31 to achieve radial expansion and contraction.

[0055] The above scheme is adopted: based on the calculation result of the coverage percentage of iron oxide nanoparticles and carbon nanotubes in the third mixture solution, the rotation speed of the intermittent Y-axis forward and reverse stirring mechanism and the X-axis stirring mechanism are proportionally adjusted by the extension and contraction action of the cylinder 31 located on both sides of the synchronous belt 3, so as to achieve uniform dispersion of the iron oxide nanoparticles and carbon nanotubes in the third mixture solution.

[0056] like Figure 1 , Figure 2 , Figure 3 and Figure 5 As shown, in order to achieve intermittent forward and reverse stirring of the raw materials in the Y-axis direction, the intermittent Y-axis forward and reverse stirring mechanism also includes a stirring shaft 46 rotatably sleeved at the center of the upper surface of the stirring tank 2, the first external gear 4 is fixedly sleeved on the outer surface of the first connecting shaft 35, the second external gear 41 is fixedly sleeved on the outer surface of the second connecting shaft 36, the first gear 42 is fixedly sleeved on the outer surface of the first connecting shaft 35 below the first external gear 4, the second gear 43 is fixedly sleeved on the outer surface of the second connecting shaft 36 below the second external gear 41, the third gear 44 is fixedly sleeved on one end of the stirring shaft 46 above the stirring tank 2, and the arc-shaped stirring blades 45 are fixedly mounted in a ring array on the outer surface of the stirring shaft 46 inside the stirring tank 2.

[0057] The above scheme is adopted: after 5%-8% of silicon dioxide powder, 1%-10% of iron oxide nanoparticles, 10%-15% of carbon nanotubes and 1%-3% of silane coupling agent are gradually added to the second mixture solution in the stirring tank 2 by weight, the control unit 8 controls the drive motor 33 of the speed change mechanism to start, and the drive motor 33 drives the speed change disc 37 connected to one end of the transmission shaft 34 to rotate with the axis of the drive motor 33 as the center of the circle, driving the meshing teeth 32 to mesh with the synchronous belt 3, and the speed change disc 37 set by the second connecting shaft 36 drives the second connecting shaft 36 to rotate, driving the second external gear 41 on the surface of the second connecting shaft 36 to achieve external meshing action with the first external gear 4 on the surface of the first connecting shaft 35. At this time, the first gear 42, the second gear 43 and the third gear 44 are driven to mesh by utilizing the opposite direction of the external meshing of the first external gear 4 and the second external gear 41, thereby driving the arc-shaped stirring blade 45 to achieve intermittent forward and reverse stirring action of the above raw materials in the Y-axis direction in the stirring tank 2.

[0058] like Figure 1 , Figure 2 , Figure 3 and Figure 5 As shown, in order to achieve stirring of the raw materials in the X-axis direction, the X-axis stirring mechanism also includes a transmission chamber 52 opened inside the stirring shaft 46, and the inner top wall of the transmission chamber 52 is rotatably sleeved with a core shaft 53, and the top end of the core shaft 53 passes through the transmission chamber 52 and extends to the top of the stirring shaft 46, and the outer surface of the core shaft 53 located above the stirring shaft 46 is rotatably sleeved with a fixing frame 54, and the lower surface of the fixing frame 54 is fixedly connected to the upper surface of the stirring tank 2, and the outer surface of the core shaft 53 located above the fixing frame 54 is fixedly sleeved with a fourth gear 55, and the outer surface of the second connecting shaft 36 located between the first outer gear 4 and the second gear 43 is fixedly sleeved with a fifth gear 56, and the fourth gear 55 is meshed with the fifth gear 56, and the outer surface of each bevel gear in the bevel gear set 5 is in contact with the transmission chamber 52. The inner wall is rotatably sleeved, and the bottom end of the core shaft 53 is fixedly sleeved with the inner wall of one of the bevel gears in the bevel gear set 5. The inner walls of eight bevel gears in the bevel gear set 5 are fixedly sleeved with a rotating shaft 57. One end of the rotating shaft 57 passes through the transmission cavity 52 and the stirring shaft 46 and then extends to the inside of the stirring tank 2. The spiral blade 51 is fixedly installed on the outer surface of the rotating stirring tank 2. The lower surface of the stirring tank 2 is fixedly connected with a discharge pipe 58 with a solenoid valve. The upper surface of the stirring tank 2 is respectively provided with a first inlet 59 and a second inlet 510. The first inlet 59 and the second inlet 510 are provided to feed materials into the stirring tank 2. A heating pipe 511 is fixedly installed on the inner bottom wall of the stirring tank 2. One end of the heating pipe 511 passes through the stirring tank 2 and then extends to the outside of the stirring tank 2.

[0059] The calculation formula for coverage area percentage is:

[0060]

[0061] Wherein, D represents the coverage area percentage of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution, X represents the number of pixels covered by the iron oxide nanoparticles and the carbon nanotubes in the image analysis result, and O represents the total number of pixels of the entire image in the image analysis result. For example, a coverage area percentage of 0.9 indicates that the speed change mechanism of the stirring equipment needs to increase the rotation speed of the intermittent Y-axis forward and reverse stirring mechanism and the X-axis stirring mechanism by 10%, and 1.1 indicates a decrease of 10%.

[0062] By adopting the above scheme, while the second connecting shaft 36 rotates, it drives the fifth gear 56 on the surface of the second connecting shaft 36 to engage with the fourth gear 55 on the surface of the core shaft 53, drives the adjacent bevel gears in the bevel gear set 5 to engage with each other, and drives the spiral blades 51 to realize the stirring action of the above-mentioned raw materials in the X-axis direction in the mixing tank 2.

[0063] When silicon dioxide powder, iron oxide nanoparticles, carbon nanotubes and silane coupling agent are gradually added to the second mixture solution and stirred, the working principle of the stirring device is as follows:

[0064] S1. After 5%-8% of silicon dioxide powder, 1%-10% of iron oxide nanoparticles, 10%-15% of carbon nanotubes and 1%-3% of silane coupling agent are gradually added to the second mixture solution in the stirring tank 2 by weight, the control unit 8 controls the drive motor 33 of the speed change mechanism to start, and the drive motor 33 drives the speed change disc 37 connected to one end of the transmission shaft 34 to rotate with the axis of the drive motor 33 as the center, driving the meshing teeth 32 to mesh with the synchronous belt 3, and the speed change disc 37 set by the second connecting shaft 36 drives the second connecting shaft 36 to rotate, driving the second external gear 41 on the surface of the second connecting shaft 36 to achieve external meshing action with the first external gear 4 on the surface of the first connecting shaft 35. At this time, the first gear 42, the second gear 43 and the third gear 44 are driven to mesh by utilizing the opposite direction of the external meshing of the first external gear 4 and the second external gear 41, thereby driving the arc-shaped stirring blade 45 to achieve intermittent forward and reverse stirring action in the Y-axis direction on the above-mentioned raw materials in the stirring tank 2;

[0065] While the second connecting shaft 36 is rotating, it drives the fifth gear 56 on the surface of the second connecting shaft 36 to mesh with the fourth gear 55 on the surface of the core shaft 53, drives the adjacent bevel gears in the bevel gear set 5 to mesh with each other, and drives the spiral blade 51 to stir the above-mentioned raw materials in the X-axis direction in the stirring tank 2, and then through the cooperation of the intermittent Y-axis forward and reverse stirring mechanism and the X-axis stirring mechanism, the above-mentioned raw materials are stirred in multiple directions to obtain a third mixture solution. In addition, the control unit 8 controls its rotation speed to 400 rpm and the stirring time to 0.3-2 hours;

[0066] S2. When a third mixture solution is formed in the stirring device, the microscope camera 61 of the acquisition unit 6 acquires an image of the dispersion of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution, and sends the data to the analysis and processing unit 7. The analysis and processing unit 7 distinguishes the dispersion area and the aggregation area of ​​the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution by edge detection, thereby obtaining an image analysis result of the dispersion of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution. Based on the image analysis result, the coverage area percentage of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution is calculated, and the uniform dispersion degree of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution is evaluated by the coverage area percentage.

[0067] S3. When the coverage area percentage is less than a preset threshold, the coverage area percentage is determined to be less than the preset threshold ratio, a proportional coefficient is formed, and a control instruction is formed by the control unit 8; according to the proportional coefficient, the rotation speed of the intermittent Y-axis forward and reverse stirring mechanism and the X-axis stirring mechanism is proportionally increased by the extension and contraction action of the cylinder 31 located on both sides of the synchronous belt 3 until the coverage area percentage is greater than or equal to the preset threshold.

[0068] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0069] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An infrared invisible aerogel, characterized by: The aerogel has a three-dimensional network porous structure, which is formed by three-dimensional construction of nanosheets, and the raw materials of the nanosheets include the following materials: polyvinyl alcohol, sodium alginate, chitosan, silicon dioxide powder, iron oxide nanoparticles, carbon nanotubes, n-butanol and silane coupling agent; The mass percentage content of each component is: polyvinyl alcohol 45%-60%, sodium alginate 5%-15%, chitosan 5%-10%, silicon dioxide powder 5%-8%, iron oxide nanoparticles 1%-10%, carbon nanotubes 10%-15%, n-butanol 5%-10% and silane coupling agent 1%-3%; The preparation method of the infrared stealth aerogel comprises the steps of: first, adding an appropriate amount of deionized water into a stirring device and heating it at a temperature of 50-80° C., then adding raw materials of 45%-60% by mass of polyvinyl alcohol, 5%-15% by mass of sodium alginate, and 5%-10% by mass of chitosan into the stirring device and mixing with the deionized water and stirring until they are completely dissolved, and finally forming a uniform first mixture solution in the stirring device, stirring the stirring device at a temperature range of 60-70° C. for 10-25 minutes, and the speed range of the stirring device is 3000-4000 rpm; Step 2: Under the condition of heating temperature of 60-70° C., 5%-10% of n-butanol by mass is added to the first mixture solution and stirred evenly to form a second mixture solution; the stirring time is 5-10 minutes, and the speed range of the stirring equipment is 2000-2500 rpm; Step 3, gradually adding 5%-8% of silicon dioxide powder, 1%-10% of iron oxide nanoparticles, 10%-15% of carbon nanotubes and 1%-3% of silane coupling agent by mass percentage into the second mixture solution and stirring evenly to form a third mixture solution, wherein the initial rotation speed of the stirring device is 400 rpm, and the stirring time is 0.3-2 hours. After the stirring is completed, the stirring device obtains and analyzes the dispersion image of the iron oxide nanoparticles and carbon nanotubes in the third mixture solution through the microscope camera (61) inside the stirring device. Based on the analysis result, if it is analyzed that the iron oxide nanoparticles and carbon nanotubes are unevenly dispersed in the third mixture solution, the ratio of the rotation speed of the stirring device is adjusted so that it corresponds to the ratio of the corresponding evaluation threshold value of the analysis result. Otherwise, proceed to the next step; Step 4: Pour the third mixture solution into a mold, and then place the mold containing the third mixture solution in a freezer for 50-60 hours at a freezing temperature of -50 to -80°C. During the freezing process, the water in the third mixture solution will gradually solidify into ice crystals. After freezing, place the sample in a vacuum and dry it. The vacuum degree range is 10 -3 -10 -6 Pa, the drying time is 85-100 hours, and the aerogel is obtained; The stirring device in step 1 comprises a support frame (1), a stirring tank (2), a speed change mechanism, an intermittent Y-axis forward and reverse stirring mechanism, and an X-axis stirring mechanism; A speed change mechanism, the speed change mechanism is located above the stirring tank (2), the speed change mechanism comprises a synchronous toothed belt (3), a cylinder (31) and meshing teeth (32), after the cylinder (31) is extended and retracted to drive the meshing teeth (32) to mesh with the synchronous toothed belt (3), the cylinder (31) located on both sides of the synchronous toothed belt (3) can be extended and retracted to realize online stepless speed change of the rotation speed of the intermittent Y-axis forward and reverse stirring mechanism and the X-axis stirring mechanism; An intermittent Y-axis forward and reverse stirring mechanism, the intermittent Y-axis forward and reverse stirring mechanism being located between the stirring tank (2) and the speed change mechanism, the intermittent Y-axis forward and reverse stirring mechanism comprising a first external gear (4), a second external gear (41), a first gear (42), a second gear (43), a third gear (44) and an arc-shaped stirring blade (45), the third gear (44) being located between the first gear (42) and the second gear (43), and the speed change mechanism being moved while driving the first external gear (4) and the second external gear (41) to achieve external meshing, at this time, utilizing the characteristic that the external meshing of the first external gear (4) and the second external gear (41) turns in opposite directions, driving the first gear (42), the second gear (43) and the third gear (44) to mesh, thereby driving the arc-shaped stirring blade (45) to achieve intermittent Y-axis forward and reverse stirring action on the raw materials of the nanosheet layer in the stirring tank (2); An X-axis stirring mechanism, the X-axis stirring mechanism being located inside the stirring tank (2), the X-axis stirring mechanism comprising a bevel gear set (5) and a spiral blade (51), and the speed change mechanism driving adjacent bevel gears in the bevel gear set (5) to mesh with each other while moving, driving the spiral blade (51) to stir the raw materials of the nanosheet layer in the stirring tank (2) in the X-axis direction; It also includes a collection unit (6), an analysis and processing unit (7) and a control unit (8), wherein: When a third mixture solution is formed in the stirring device, a collection unit (6) collects images of the dispersion of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution, and sends the data to an analysis and processing unit (7). The analysis and processing unit (7) uses edge detection to distinguish the dispersed area and the aggregated area of ​​the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution, thereby obtaining an image analysis result of the dispersion of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution. Based on the image analysis result, the coverage area percentage of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution is calculated, and the uniform dispersion degree of the iron oxide nanoparticles and the carbon nanotubes in the third mixture solution is evaluated according to the coverage area percentage. When the coverage area percentage is less than a preset threshold, determining that the coverage area percentage is less than the preset threshold ratio, forming a proportional coefficient, and the control unit (8) forms a control instruction; according to the proportional coefficient, the speed change mechanism of the stirring device increases the rotation speed of the intermittent Y-axis forward and reverse stirring mechanism and the X-axis stirring mechanism in equal proportion until the coverage area percentage is greater than or equal to the preset threshold; When the coverage area percentage is greater than or equal to the preset threshold, proceed to the next step.

2. The infrared invisible aerogel according to claim 1, characterized in that: The microscope camera (61) is fixedly mounted on the inner top wall of the stirring tank (2); the inner wall of the support frame (1) is fixedly sleeved with the outer surface of the stirring tank (2); a temperature sensor (9) is fixedly mounted on the outer surface of the stirring tank (2); a detection end of the temperature sensor (9) passes through the stirring tank (2) and extends to the interior of the stirring tank (2); the speed change mechanism further comprises a drive motor (33) fixedly mounted on the right outer surface of the stirring tank (2); an output shaft of the drive motor (33) is fixedly mounted with a transmission shaft (34) via a coupling; and the stirring tank The upper surface of the mixing tank (2) is respectively rotatably sleeved with a first connecting shaft (35) and a second connecting shaft (36), and the first connecting shaft (35) and the second connecting shaft (36) are symmetrically distributed on the upper surface of the mixing tank (2) with the axis of the mixing tank (2) as the symmetry center, and one end of the second connecting shaft (36) and the transmission shaft (34) are fixedly sleeved with a speed change disk (37), the cylinder (31) is fixedly mounted on the radial direction of the outer surface of the speed change disk (37), and the meshing teeth (32) are fixedly mounted on the outer end of the piston rod of the cylinder (31) to achieve radial expansion and contraction.

3. The infrared invisible aerogel according to claim 2, characterized in that: The intermittent Y-axis forward and reverse stirring mechanism also includes a stirring shaft (46) rotatably sleeved at the center of the upper surface of the stirring tank (2); the first external gear (4) is fixedly sleeved on the outer surface of the first connecting shaft (35); the second external gear (41) is fixedly sleeved on the outer surface of the second connecting shaft (36); the first gear (42) is fixedly sleeved on the outer surface of the first connecting shaft (35) located below the first external gear (4); the second gear (43) is fixedly sleeved on the outer surface of the second connecting shaft (36) located below the second external gear (41); the third gear (44) is fixedly sleeved on one end of the stirring shaft (46) located above the stirring tank (2); and the arc-shaped stirring blades (45) are fixedly mounted in an annular array on the outer surface of the stirring shaft (46) located inside the stirring tank (2).

4. The infrared invisible aerogel according to claim 3, characterized in that: The X-axis stirring mechanism also includes a transmission chamber (52) opened inside the stirring shaft (46), the inner top wall of the transmission chamber (52) is rotatably sleeved with a core shaft (53), the top end of the core shaft (53) passes through the transmission chamber (52) and extends to the top of the stirring shaft (46), and the outer surface of the core shaft (53) located above the stirring shaft (46) is rotatably sleeved with a fixing frame (54).

5. The infrared invisible aerogel according to claim 4, characterized in that: The lower surface of the fixing frame (54) is fixedly connected to the upper surface of the stirring tank (2); the outer surface of the core shaft (53) located above the fixing frame (54) is fixedly sleeved with a fourth gear (55); the outer surface of the second connecting shaft (36) located between the first external gear (4) and the second gear (43) is fixedly sleeved with a fifth gear (56); the fourth gear (55) is meshed with the fifth gear (56).

6. The infrared invisible aerogel according to claim 5, characterized in that: The outer surface of each bevel gear in the bevel gear set (5) is rotatably sleeved with the inner wall of the transmission chamber (52); the bottom end of the core shaft (53) is fixedly sleeved with the inner wall of one of the bevel gears in the bevel gear set (5); a rotating shaft (57) is fixedly sleeved on the inner walls of eight of the bevel gears in the bevel gear set (5); one end of the rotating shaft (57) passes through the transmission chamber (52) and the stirring shaft (46) and then extends to the inside of the stirring tank (2); the spiral blade (51) is fixedly mounted on the outer surface of the spiral blade (51) rotatably located in the stirring tank (2); a discharge pipe (58) with a solenoid valve is fixedly connected to the lower surface of the stirring tank (2); a first inlet (59) and a second inlet (510) are respectively opened on the upper surface of the stirring tank (2); a heating pipe (511) is fixedly mounted on the inner bottom wall of the stirring tank (2); one end of the heating pipe (511) passes through the stirring tank (2) and then extends to the outside of the stirring tank (2).

7. The infrared invisible aerogel according to claim 6, characterized in that: The calculation formula for the coverage area percentage is: Wherein, D represents the coverage area percentage of iron oxide nanoparticles and carbon nanotubes in the third mixture solution, X represents the number of pixels covered by iron oxide nanoparticles and carbon nanotubes in the image analysis result, and O represents the total number of pixels of the entire image in the image analysis result.

Images