High-speed stirring and atomization coating combined powder insulation method and insulation powder

Abstract

The invention provides a high-speed stirring and atomization coating combined powder insulation method and insulation powder, and the powder insulation method comprises the following steps: (1) enabling the powder to be in a high-speed stirring state in a closed space, and enabling powder particles to be spheroidized; (2) while the step (1) is carried out, introducing an insulating agent into the closed space in an atomized manner, and carrying out insulating coating on the spheroidized powder particles; (3) continuously stirring after stopping introducing the insulating agent, and discharging to obtain insulating powder; wherein the rotating speed of the high-speed stirring state in the step (1) is larger than or equal to 2500rpm, and the linear speed of the powder particles in the stirring process is larger than or equal to 40m / s. According to the powder insulation method provided by the invention, the sphericity of the powder and the uniformity of insulation coating are improved, the apparent density of particles is improved, meanwhile, the technological process is simplified, the treatment cost is reduced, and large-scale popularization and application are facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of powder material processing, and relates to a powder material insulation method, and in particular to a high-speed stirring combined with atomization coating powder material insulation method and insulating powder material. Background Art

[0002] The traditional powder insulation method is to pour the powder into a mixer, dissolve the insulating agent in a specific solvent, and add the insulating agent solution to the powder and mix them evenly, so that the surface of the powder particles is covered with an insulating film. The powder insulation obtained by the above traditional method has poor consistency, especially when the powder particles are irregular, and the fluidity and bulk density of the particles after insulation treatment are not ideal. In addition, some solvents used in the insulating agent will have an adverse impact on the environment after evaporation, which does not meet the green and environmentally friendly production requirements.

[0003] CN 113697806A discloses a liquid-phase mechanical fusion coated artificial graphite material and a preparation method thereof, wherein the petroleum coke raw material is first mechanically crushed, and then the shape is improved and fine powder is removed by a shaping machine to obtain a shaped powder; the shaped powder is subjected to high-temperature heat treatment to obtain an artificial graphite material A; the artificial graphite material A is taken, and a liquid-phase coating agent is added, and the mixture is stirred to obtain an artificial graphite material B; the artificial graphite material B is subjected to low-temperature heat treatment and then crushed and shaped to obtain an artificial graphite material C; the artificial graphite material C is loaded into a box and placed in a carbonization kiln for high-temperature treatment, and then cooled to room temperature for crushing and classification to obtain a liquid-phase mechanical fusion coated artificial graphite material. The invention only mentions that the material is improved in shape and then subjected to liquid-phase coating, and does not involve how to increase the bulk density of the particles.

[0004] CN 113257561A discloses an insulating coated alloy powder and a preparation method thereof, comprising the following steps: (1) coating the alloy powder and the atomized insulating coating agent, and breaking up and drying the alloy powder under an airflow of a predetermined speed and a predetermined temperature; (2) performing gas-solid separation to obtain the insulating coated alloy powder. The invention merely breaks up the powder by a certain rotation speed, and then improves the insulation by atomization coating, and also does not involve how to improve the bulk density of the particles.

[0005] It can be seen that how to provide a powder insulation method, improve the sphericity of the powder and the uniformity of the insulation coating, increase the loose density of the particles, and at the same time simplify the process flow and reduce the processing cost has become an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0006] The purpose of the present invention is to provide a high-speed stirring combined with atomization coating powder insulation method and insulating powder, the powder insulation method improves the sphericity of the powder and the uniformity of the insulating coating, increases the loose density of the particles, simplifies the process flow, reduces the processing cost, and is conducive to large-scale promotion and application.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a powder insulation method of high-speed stirring combined with atomization coating, the powder insulation method comprising the following steps:

[0009] (1) The powder is stirred at high speed in a closed space to make the powder particles spherical;

[0010] (2) while step (1) is being performed, an insulating agent is introduced into the enclosed space in an atomized manner to provide insulation coating to the spherical powder particles;

[0011] (3) After the insulating agent stops being introduced, stirring is continued to obtain insulating powder after discharging.

[0012] Wherein, the rotation speed of the high-speed stirring state in step (1) is ≥2500rpm, for example, it can be 2500rpm, 2600rpm, 2700rpm, 2800rpm, 2900rpm, 3000rpm, 3100rpm, 3200rpm, 3300rpm, 3400rpm or 3500rpm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0013] The linear velocity of the powder particles during the stirring process is ≥40m / s, for example, it can be 40m / s, 42m / s, 44m / s, 46m / s, 48m / s, 50m / s, 52m / s, 54m / s, 56m / s, 58m / s or 60m / s, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] The powder insulation method provided by the present invention first puts the powder in a high-speed stirring state, and utilizes the collision, cutting and friction kneading between the powder particles and the stirring paddle and the powder particles to sphericalize the originally irregularly shaped powder particles, so as to improve the uniformity of the subsequent insulation coating; and then the powder particles are insulated and coated by atomizing the insulating agent, thereby reducing the use of organic solvents as much as possible. This method of simultaneously performing powder shaping and insulation coating significantly improves the insulation efficiency of the powder and the loose density of the particles, promotes rapid mixing of the powder, simplifies the process flow, reduces processing costs, and is conducive to large-scale promotion and application.

[0015] Preferably, the material of the powder in step (1) includes any one of iron, silicon or chromium, or a combination of at least two of them. Typical but non-limiting combinations include a combination of iron and silicon, a combination of silicon and chromium, a combination of iron and chromium, or a combination of iron, silicon and chromium. More preferably, it is an iron-silicon alloy, an iron-chromium alloy or an iron-silicon-chromium alloy.

[0016] Preferably, the average particle size of the powder in step (1) is 300-400 mesh, for example, 300 mesh, 310 mesh, 320 mesh, 330 mesh, 340 mesh, 350 mesh, 360 mesh, 370 mesh, 380 mesh, 390 mesh or 400 mesh, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, based on the total volume of the enclosed space, the amount of powder added in step (1) is 5-30 vol%, for example, it can be 5 vol%, 6 vol%, 8 vol%, 10 vol%, 12 vol%, 14 vol%, 16 vol%, 18 vol%, 20 vol%, 22 vol%, 24 vol%, 26 vol%, 28 vol% or 30 vol%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] Preferably, the enclosed space in step (1) is a truncated cone structure.

[0019] Preferably, taking the direction of gravity as a reference, the truncated cone-shaped structure presents a spatial distribution that is wider at the top and narrower at the bottom.

[0020] Preferably, at least two groups of stirring paddles are arranged on the central axis of the enclosed space in step (1), for example, 2 groups, 3 groups, 4 groups, 5 groups, 6 groups, 7 groups or 8 groups, but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Preferably, the agitator paddle comprises any one of turbine type, propeller type, inclined propeller type or anchor type, or a combination of at least two of them. Typical but non-limiting combinations include a combination of turbine type and propeller type, a combination of propeller type and inclined propeller type, a combination of inclined propeller type and anchor type, a combination of turbine type, propeller type and inclined propeller type, a combination of propeller type, inclined propeller type and anchor type, or a combination of turbine type, propeller type, inclined propeller type and anchor type.

[0022] The present invention effectively promotes the full sphericity of powder particles by synergistically combining various forms of stirring paddles, and further improves the uniformity of subsequent insulation coating.

[0023] In the present invention, all forms of stirring paddles are stirring paddles commonly used in the art, as long as they can achieve the stirring function, so the specific structure and shape of each form of stirring paddle are not particularly limited here.

[0024] Preferably, the distance between the edge of the stirring paddle and the side wall of the confined space is set to d, and the cross-sectional diameter of the confined space in the plane where the stirring paddle is located is D, then d / D=1 / 20-1 / 10, for example, it can be 1 / 20, 1 / 19, 1 / 18, 1 / 17, 1 / 16, 1 / 15, 1 / 14, 1 / 13, 1 / 12, 1 / 11 or 1 / 10, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] In the present invention, the edge of the stirring paddle specifically refers to the edge of the circumscribed circle of the stirring paddle, and the distance d refers to the distance between the edge of the circumscribed circle of the stirring paddle and the side wall of the enclosed space.

[0026] The present invention controls d / D within a reasonable range and combines a confined space with a truncated cone structure that is wide at the top and narrow at the bottom, so that after entering the confined space, the powder particles are carried from the bottom to the top due to the negative pressure effect under the rotation of the stirring paddle, and then return from the top to the bottom under the action of gravity, and the cycle is repeated. The powder particles circulate in the confined space, thereby achieving full sphericalization of the powder particles.

[0027] Preferably, step (1) is started to introduce the insulating agent in step (2) after 2-5 minutes, for example, it can be 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes or 5 minutes, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] Preferably, the introduction point of the insulating agent in step (2) is set at the top of the enclosed space.

[0029] Preferably, based on the total mass of the powder particles, the amount of the insulating agent introduced in step (2) is 0.3-0.5wt%, for example, it can be 0.3wt%, 0.32wt%, 0.34wt%, 0.36wt%, 0.38wt%, 0.4wt%, 0.42wt%, 0.44wt%, 0.46wt%, 0.48wt% or 0.5wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] Preferably, the insulating agent in step (2) comprises any one of a silane coupling agent, potassium silicate, silica sol, aluminum dihydrogen phosphate or phosphoric acid, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of a silane coupling agent and potassium silicate, a combination of potassium silicate and silica sol, a combination of silica sol and aluminum dihydrogen phosphate, a combination of aluminum dihydrogen phosphate and phosphoric acid, a combination of a silane coupling agent, potassium silicate and silica sol, a combination of potassium silicate, silica sol and aluminum dihydrogen phosphate, or a combination of silica sol, aluminum dihydrogen phosphate and phosphoric acid.

[0031] Preferably, the silane coupling agent includes any one of a methoxysilane coupling agent, an ethoxysilane coupling agent or a mercaptopropyl silane coupling agent, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of a methoxysilane coupling agent and an ethoxysilane coupling agent, a combination of an ethoxysilane coupling agent and a mercaptopropyl silane coupling agent, a combination of a methoxysilane coupling agent and a mercaptopropyl silane coupling agent, or a combination of a methoxysilane coupling agent, an ethoxysilane coupling agent and a mercaptopropyl silane coupling agent.

[0032] Preferably, the insulating agent in step (2) is dissolved in an organic solvent and subsequently atomized.

[0033] Preferably, the organic solvent comprises any one of acetone, butanone, isopropanol, dimethyl carbonate, ethanol or ethyl acetate, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of acetone and butanone, a combination of butanone and isopropanol, a combination of isopropanol and dimethyl carbonate, a combination of dimethyl carbonate and ethanol, a combination of ethanol and ethyl acetate, a combination of acetone, butanone and isopropanol, a combination of butanone, isopropanol and dimethyl carbonate, a combination of isopropanol, dimethyl carbonate and ethanol, or a combination of dimethyl carbonate, ethanol and ethyl acetate.

[0034] Preferably, stirring is continued for 5-10 min after the insulating agent is stopped in step (3), for example, it can be 5 min, 5.5 min, 6 min, 6.5 min, 7 min, 7.5 min, 8 min, 8.5 min, 9 min, 9.5 min or 10 min, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] As a preferred technical solution of the first aspect of the present invention, the powder insulation method comprises the following steps:

[0036] (1) A powder with an average particle size of 300-400 mesh is placed in a confined space of a truncated cone structure and stirred at a high speed of ≥2500 rpm. Taking the direction of gravity as a reference, the truncated cone structure presents a spatial distribution that is wide at the top and narrow at the bottom. The linear velocity of the powder particles during the stirring process is ≥40 m / s, so that the powder particles are spherical. Taking the total volume of the confined space as a reference, the amount of the powder added is 5-30 vol%, and the material of the powder includes iron-silicon alloy, iron-chromium alloy or iron-silicon-chromium alloy. At least two groups of stirring paddles are arranged on the central axis of the confined space, and the form of the stirring paddles includes any one of turbine type, propeller type, oblique paddle type or anchor type or a combination of at least two of them. The distance between the edge of the stirring paddle and the side wall of the confined space is set as d, and the diameter of the confined space cross section of the plane where the stirring paddle is located is D, then d / D=1 / 20-1 / 10;

[0037] (2) After step (1) is performed for 2-5 minutes, an insulating agent is dissolved in an organic solvent and introduced into the enclosed space from the top of the enclosed space in an atomized manner to perform insulation coating on the spherical powder particles; the amount of the insulating agent introduced is 0.3-0.5wt% based on the total mass of the powder particles; the insulating agent comprises any one or a combination of at least two of a silane coupling agent, potassium silicate, silica sol, aluminum dihydrogen phosphate or phosphoric acid, and the silane coupling agent comprises any one or a combination of at least two of a methoxysilane coupling agent, an ethoxysilane coupling agent or a mercaptopropyl silane coupling agent; the organic solvent comprises any one or a combination of at least two of acetone, butanone, isopropyl alcohol, dimethyl carbonate, ethanol or ethyl acetate;

[0038] (3) After the insulating agent stops being introduced, stirring is continued for 5-10 minutes to obtain insulating powder after discharge.

[0039] In a second aspect, the present invention provides an insulating powder, wherein the insulating powder is prepared by the method described in the first aspect, and the insulation resistance of the insulating powder is ≥2.5×10 6 MΩ, for example, can be 2.5×10 6 MΩ, 2.6×10 6 MΩ, 2.7×10 6 MΩ, 2.8×10 6 MΩ、2.9×10 6 MΩ or 3×10 6 MΩ, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] In the present invention, the bulk ratio of the insulating powder is 2.18-2.22 g / cm 3 , for example, it can be 2.18 g / cm 3 , 2.19g / cm3 , 2.20g / cm 3 , 2.21g / cm 3 or 2.22 g / cm 3 , but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The powder insulation method provided by the present invention first puts the powder in a high-speed stirring state, and utilizes the collision, cutting and friction kneading between the powder particles and the stirring paddle and the powder particles to sphericalize the originally irregularly shaped powder particles, so as to improve the uniformity of the subsequent insulation coating; and then the powder particles are insulated and coated by atomizing the insulating agent, thereby reducing the use of organic solvents as much as possible. This method of simultaneously performing powder shaping and insulation coating significantly improves the insulation efficiency of the powder and the loose density of the particles, promotes rapid mixing of the powder, simplifies the process flow, reduces processing costs, and is conducive to large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a diagram of the device used in the high-speed stirring combined with atomization coating powder insulation method provided by the present invention;

[0044] Figure 2 It is a schematic diagram of the insulation coating of powder particles in the powder insulation method provided by the present invention.

[0045] Among them: 1-feeding port; 2-atomizing nozzle; 3-stirring paddle; 31-turbine stirring paddle; 32-rotor stirring paddle; 33-oblique paddle stirring paddle; 4-pressure gauge; 5-discharging port. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0047] The present invention provides a high-speed stirring combined with atomization coating powder insulation method and insulating powder, wherein the powder insulation method is as follows: Figure 1 The method is carried out in the device shown in the figure, which specifically includes the following steps:

[0048] (1) A powder with an average particle size of 300-400 mesh is loaded into a mixing barrel of a truncated cone structure from a feed port 1, and the mixing barrel is in a high-speed stirring state with a rotation speed of ≥2500rpm. Taking the direction of gravity as a reference, the truncated cone structure presents a spatial distribution that is wide at the top and narrow at the bottom, and the linear velocity of the powder particles during the stirring process is ≥40m / s, so that the powder particles are spherical; based on the total volume of the mixing barrel, the amount of the powder added is 5-30vol%, and the material of the powder includes iron-silicon alloy, iron-chromium alloy or iron-silicon-chromium alloy; at least two groups of stirring paddles 3 are arranged on the central axis of the mixing barrel, and the form of the stirring paddle 3 includes any one of turbine type, propeller type, inclined paddle type or anchor type or a combination of at least two of them; the distance between the edge of the stirring paddle 3 and the side wall of the mixing barrel is set to d, and the diameter of the mixing barrel cross section of the plane where the stirring paddle 3 is located is D, then d / D=1 / 20-1 / 10;

[0049] (2) After step (1) is performed for 2-5 minutes, an insulating agent is dissolved in an organic solvent and introduced into the stirring barrel from an atomizing nozzle 2 on the top of the stirring barrel in an atomized manner to perform insulation coating on the spherical powder particles, and during the insulation coating process, the value of the pressure gauge 4 is monitored to be stable near normal pressure; based on the total mass of the powder particles, the amount of the insulating agent introduced is 0.3-0.5wt%; the insulating agent includes any one or a combination of at least two of a silane coupling agent, potassium silicate, silica sol, aluminum dihydrogen phosphate or phosphoric acid, and the silane coupling agent includes any one or a combination of at least two of a methoxysilane coupling agent, an ethoxysilane coupling agent or a mercaptopropyl silane coupling agent; the organic solvent includes any one or a combination of at least two of acetone, butanone, isopropyl alcohol, dimethyl carbonate, ethanol or ethyl acetate;

[0050] (3) After the introduction of the insulating agent stops, stirring is continued for 5-10 minutes to obtain insulating powder through the discharge port 5.

[0051] The insulation resistance of the insulating powder obtained by the above method is ≥2.5×10 6 MΩ, loose weight ratio is 2.18-2.22g / cm 3 .

[0052] Compared with conventional ordinary stirring, the insulation coating schematic diagram of the powder particles in the powder insulation method provided by the present invention is shown in Figure 2 .

[0053] It can be seen that the powder insulation method provided by the present invention first puts the powder in a high-speed stirring state, and utilizes the collision, cutting and friction kneading between the powder particles and the stirring paddle and the powder particles to sphericalize the originally irregularly shaped powder particles, so as to improve the uniformity of the subsequent insulation coating; and then the powder particles are insulated and coated by atomizing the insulating agent, thereby reducing the use of organic solvents as much as possible. This method of simultaneously performing powder shaping and insulation coating significantly improves the insulation efficiency of the powder and the loose density of the particles, promotes rapid mixing of the powder, simplifies the process flow, reduces processing costs, and is conducive to large-scale promotion and application.

[0054] Example 1

[0055] This embodiment provides a powder insulation method and insulating powder material with high-speed stirring and atomization coating. The powder insulation method is as follows: Figure 1 The method is carried out in the device shown in the figure, which specifically includes the following steps:

[0056] (1) An iron-silicon-chromium alloy powder having an average particle size of 325 mesh is loaded into a mixing barrel having a truncated cone structure from a feed port 1, and the mixing barrel is placed in a high-speed mixing state with a rotation speed of 2600 rpm. Taking the direction of gravity as a reference, the truncated cone structure presents a spatial distribution that is wide at the top and narrow at the bottom. The linear velocity of the powder particles during the mixing process is 45 m / s, so that the powder particles are spherical. Taking the total volume of the mixing barrel as a reference, the amount of the powder added is 20 vol%. Four groups of stirring paddles 3 are arranged on the central axis of the mixing barrel, and the first group from top to bottom is a turbine stirring paddle 31, the second group is a propeller stirring paddle 32, and the third and fourth groups are oblique paddle stirring paddles 33. The distance between the edge of the stirring paddle 3 and the side wall of the mixing barrel is set to d, and the diameter of the mixing barrel cross section of the plane where the stirring paddle 3 is located is D, then d / D=1 / 15.

[0057] (2) After step (1) is performed for 3 minutes, an insulating agent is dissolved in acetone and introduced into the stirring barrel from an atomizing nozzle 2 on the top of the stirring barrel in an atomized manner to perform insulation coating on the spherical powder particles, and during the insulation coating process, the value of the pressure gauge 4 is monitored to be stable near normal pressure; based on the total mass of the powder particles, the amount of the insulating agent introduced is 0.4wt%; the insulating agent includes methoxysilane coupling agent, potassium silicate, silica sol, aluminum dihydrogen phosphate and phosphoric acid;

[0058] (3) After the introduction of the insulating agent stops, stirring is continued for 5 minutes to obtain insulating powder through the discharge port 5.

[0059] Example 2

[0060] This embodiment provides a powder insulation method and insulating powder material with high-speed stirring and atomization coating. The powder insulation method is as follows: Figure 1The method is carried out in the device shown in the figure, which specifically includes the following steps:

[0061] (1) A ferrosilicon alloy powder with an average particle size of 300 mesh is loaded into a mixing barrel of a truncated cone structure from a feed port 1, and the mixing barrel is in a high-speed stirring state of 2500 rpm. Taking the direction of gravity as a reference, the truncated cone structure presents a spatial distribution that is wide at the top and narrow at the bottom. The linear velocity of the powder particles during the stirring process is 40 m / s, so that the powder particles are spherical. Taking the total volume of the mixing barrel as a reference, the amount of the powder added is 5 vol%. Four groups of stirring paddles 3 are arranged on the central axis of the mixing barrel, and the first group from top to bottom is a turbine stirring paddle 31, the second group is a propeller stirring paddle 32, and the third and fourth groups are oblique paddle stirring paddles 33. The distance between the edge of the stirring paddle 3 and the side wall of the mixing barrel is set to d, and the diameter of the mixing barrel cross section of the plane where the stirring paddle 3 is located is D, then d / D=1 / 20;

[0062] (2) After step (1) is performed for 2 minutes, an insulating agent is dissolved in isopropanol and introduced into the stirring barrel from the atomizing nozzle 2 on the top of the stirring barrel in an atomized manner to perform insulation coating on the spherical powder particles, and during the insulation coating process, the value of the pressure gauge 4 is monitored to be stable near normal pressure; based on the total mass of the powder particles, the amount of the insulating agent introduced is 0.3wt%; the insulating agent includes ethoxysilane coupling agent, potassium silicate, silica sol, aluminum dihydrogen phosphate and phosphoric acid;

[0063] (3) After the introduction of the insulating agent stops, stirring is continued for 8 minutes to obtain insulating powder through the discharge port 5.

[0064] Example 3

[0065] This embodiment provides a powder insulation method and insulating powder material with high-speed stirring and atomization coating. The powder insulation method is as follows: Figure 1 The method is carried out in the device shown in the figure, which specifically includes the following steps:

[0066] (1) A ferrochromium alloy powder with an average particle size of 400 mesh is loaded into a mixing barrel of a truncated cone structure from a feed port 1, and the mixing barrel is in a high-speed stirring state of 3000 rpm. Taking the direction of gravity as a reference, the truncated cone structure presents a spatial distribution that is wide at the top and narrow at the bottom. The linear velocity of the powder particles during the stirring process is 50 m / s, so that the powder particles are spherical. Taking the total volume of the mixing barrel as a reference, the amount of the powder added is 30 vol%. Four groups of stirring paddles 3 are arranged on the central axis of the mixing barrel, and the first group from top to bottom is a turbine stirring paddle 31, the second group is a propeller stirring paddle 32, and the third and fourth groups are oblique paddle stirring paddles 33. The distance between the edge of the stirring paddle 3 and the side wall of the mixing barrel is set to d, and the diameter of the mixing barrel cross section of the plane where the stirring paddle 3 is located is D, then d / D=1 / 10;

[0067] (2) After step (1) is performed for 5 minutes, an insulating agent is dissolved in ethyl acetate and introduced into the stirring barrel from the atomizing nozzle 2 on the top of the stirring barrel in an atomized manner to perform insulation coating on the spherical powder particles, and during the insulation coating process, the value of the pressure gauge 4 is monitored to be stable near normal pressure; the amount of the insulating agent introduced is 0.5 wt% based on the total mass of the powder particles; the insulating agent includes mercaptopropyl silane coupling agent, potassium silicate, silica sol, aluminum dihydrogen phosphate and phosphoric acid;

[0068] (3) After the introduction of the insulating agent stops, stirring is continued for 10 minutes to obtain insulating powder through the discharge port 5.

[0069] Example 4

[0070] This embodiment provides a high-speed stirring combined with atomization coating powder insulation method and insulating powder. In the powder insulation method, except that the ratio of d / D in step (1) is changed to 1 / 5, the other steps and conditions remain unchanged.

[0071] Example 5

[0072] This embodiment provides a high-speed stirring combined with atomization coating powder insulation method and insulating powder. In the powder insulation method, except that the ratio of d / D in step (1) is changed to 1 / 25, the other steps and conditions remain unchanged.

[0073] Comparative Example 1

[0074] This comparative example provides a powder insulation method and insulating powder with stirring combined with atomization coating. In the powder insulation method, except that the rotation speed of the high-speed stirring state in step (1) is reduced to 2000 rpm and the linear speed of the powder particles during the stirring process is 30 m / s, the other steps and conditions remain unchanged.

[0075] Compared with Example 1, this comparative example significantly reduces the stirring speed, and the linear speed of the powder particles is also reduced accordingly, resulting in the collision, cutting and friction kneading between the powder particles and the stirring paddle and the powder particles being insufficient to sphericalize the originally irregularly shaped powder particles, thereby affecting the uniformity of the subsequent insulation coating.

[0076] After testing (refer to GB / T 31057.2-2018 Physical Properties Test of Granular Materials), the performance parameters of the insulating powders obtained in Examples 1-5 and Comparative Example 1 are shown in Table 1 below.

[0077] Table 1

[0078] Insulation powder <![CDATA[Bulk ratio (g / cm 3 )]]> Liquidity(s) <![CDATA[Insulation resistance (×10 6 MΩ)]]> Example 1 2.22 45.3 3.08 Example 2 2.18 46.4 2.51 Example 3 2.19 46.8 2.79 Example 4 2.21 46.2 2.68 Example 5 2.20 45.1 3.06 Comparative Example 1 1.97 50.7 1.22

[0079] It can be seen that the powder insulation method provided by the present invention first puts the powder in a high-speed stirring state, and utilizes the collision, cutting and friction kneading between the powder particles and the stirring paddle and the powder particles to sphericalize the originally irregularly shaped powder particles, so as to improve the uniformity of the subsequent insulation coating; and then the powder particles are insulated and coated by atomizing the insulating agent, thereby reducing the use of organic solvents as much as possible. This method of simultaneously performing powder shaping and insulation coating significantly improves the insulation efficiency of the powder and the loose density of the particles, promotes rapid mixing of the powder, simplifies the process flow, reduces processing costs, and is conducive to large-scale promotion and application.

[0080] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A high-speed stirring combined with atomization coating powder insulation method, characterized in that: The powder insulation method comprises the following steps: (1) The powder is stirred at high speed in a closed space to make the powder particles spherical; (2) while step (1) is being performed, an insulating agent is introduced into the enclosed space in an atomized manner to provide insulation coating to the spherical powder particles; (3) After the insulating agent stops being introduced, stirring is continued to obtain insulating powder after discharging; Wherein, the rotation speed of the high-speed stirring state in step (1) is ≥2500rpm, and the linear speed of the powder particles during the stirring process is ≥40m / s.

2. The powder insulation method according to claim 1, characterized in that: The material of the powder in step (1) includes any one of iron, silicon or chromium, or a combination of at least two of them, and is more preferably iron-silicon alloy, iron-chromium alloy or iron-silicon-chromium alloy.

3. The powder insulation method according to claim 1 or 2, characterized in that: The average particle size of the powder in step (1) is 300-400 mesh; Preferably, based on the total volume of the enclosed space, the amount of the powder added in step (1) is 5-30 vol%.

4. The powder insulation method according to any one of claims 1 to 3, characterized in that: The enclosed space in step (1) is a truncated cone structure; Preferably, taking the direction of gravity as a reference, the truncated cone-shaped structure presents a spatial distribution that is wider at the top and narrower at the bottom.

5. The powder insulation method according to any one of claims 1 to 4, characterized in that: At least two groups of stirring paddles are arranged on the central axis of the enclosed space in step (1); Preferably, the stirring paddle includes any one of turbine type, propeller type, inclined paddle type or anchor type, or a combination of at least two of them.

6. The powder insulation method according to claim 5, characterized in that: Assuming that the distance between the edge of the stirring paddle and the side wall of the enclosed space is d, and the cross-sectional diameter of the enclosed space on the plane where the stirring paddle is located is D, then d / D=1 / 20-1 / 10.

7. The powder insulation method according to any one of claims 1 to 6, characterized in that: After step (1) has been carried out for 2-5 minutes, the introduction of the insulating agent in step (2) is started; Preferably, the insulating agent in step (2) is introduced at the top of the enclosed space; Preferably, based on the total mass of the powder particles, the amount of the insulating agent introduced in step (2) is 0.3-0.5 wt %.

8. The powder insulation method according to any one of claims 1 to 7, characterized in that: The insulating agent in step (2) comprises any one of silane coupling agent, potassium silicate, silica sol, aluminum dihydrogen phosphate or phosphoric acid, or a combination of at least two thereof; Preferably, the silane coupling agent includes any one of a methoxysilane coupling agent, an ethoxysilane coupling agent or a mercaptopropyl silane coupling agent, or a combination of at least two thereof; Preferably, the insulating agent in step (2) is dissolved in an organic solvent and subsequently atomized; Preferably, the organic solvent comprises any one or a combination of at least two of acetone, butanone, isopropanol, dimethyl carbonate, ethanol or ethyl acetate; Preferably, stirring is continued for 5-10 minutes after the introduction of the insulating agent in step (3) is stopped.

9. The powder insulation method according to any one of claims 1 to 8, characterized in that: The powder insulation method comprises the following steps: (1) A powder with an average particle size of 300-400 mesh is placed in a confined space of a truncated cone structure and stirred at a high speed of ≥2500 rpm. Taking the direction of gravity as a reference, the truncated cone structure presents a spatial distribution that is wide at the top and narrow at the bottom. The linear velocity of the powder particles during the stirring process is ≥40 m / s, so that the powder particles are spherical. Taking the total volume of the confined space as a reference, the amount of the powder added is 5-30 vol%, and the material of the powder includes iron-silicon alloy, iron-chromium alloy or iron-silicon-chromium alloy. At least two groups of stirring paddles are arranged on the central axis of the confined space, and the form of the stirring paddles includes any one of turbine type, propeller type, oblique paddle type or anchor type or a combination of at least two of them. The distance between the edge of the stirring paddle and the side wall of the confined space is set as d, and the diameter of the confined space cross section of the plane where the stirring paddle is located is D, then d / D=1 / 20-1 / 10; (2) After step (1) is performed for 2-5 minutes, an insulating agent is dissolved in an organic solvent and introduced into the enclosed space from the top of the enclosed space in an atomized manner to perform insulation coating on the spherical powder particles; the amount of the insulating agent introduced is 0.3-0.5wt% based on the total mass of the powder particles; the insulating agent comprises any one or a combination of at least two of a silane coupling agent, potassium silicate, silica sol, aluminum dihydrogen phosphate or phosphoric acid, and the silane coupling agent comprises any one or a combination of at least two of a methoxysilane coupling agent, an ethoxysilane coupling agent or a mercaptopropyl silane coupling agent; the organic solvent comprises any one or a combination of at least two of acetone, butanone, isopropyl alcohol, dimethyl carbonate, ethanol or ethyl acetate; (3) After the insulating agent stops being introduced, stirring is continued for 5-10 minutes to obtain insulating powder after discharge.

10. An insulating powder, characterized in that: The insulating powder is prepared by the method according to any one of claims 1 to 9, and the insulation resistance of the insulating powder is ≥ 2.5×10 6 MΩ, loose weight ratio is 2.18-2.22g / cm 3 .

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