Infrared emission material with core-shell structure and preparation method thereof

Abstract

The invention discloses a core-shell structure infrared emission material and a preparation method thereof.The preparation method comprises the following steps that S1, silicon dioxide powder, absolute ethyl alcohol and an amino silane coupling agent are mixed, heated and stirred, and first mixed slurry is obtained; s2, centrifugally separating the cooled first mixed slurry, and drying the obtained centrifugal precipitate; s3, mixing the dried centrifugal precipitate with a nitrate mixed solution containing Mn < 2 + >, Fe < 3 + >, Co < 2 + > and Cu < 2 + >, stirring and adsorbing to obtain second mixed slurry; s4, carrying out suction filtration and washing on the second mixed slurry, and drying the washed solid powder; and S5, putting the dried solid powder into a muffle furnace, calcining at a constant temperature, and cooling to obtain the core-shell structure infrared emission material with SiO2 as an inner core and Mn-Fe-Co-Cu spinel nanoparticles as an outer layer. The infrared emission material disclosed by the invention is more uniform in powder component and controllable in crystal grain, and the emissivity of an emission base material is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared emitting materials, in particular to a core-shell structure infrared emitting material and a preparation method thereof. Background Art

[0002] In high-temperature industrial furnaces exceeding 800°C, the theoretical proportion of radiative heat transfer exceeds 80% of the three heat transfer modes (radiation, convection, and conduction). Therefore, radiative heat transfer is the dominant factor in determining the thermal efficiency of high-temperature furnaces, and enhancing radiative heat transfer within the furnace is the only way to reduce the energy consumption of thermal furnaces. Applying a high-emissivity infrared radiation coating material to the inner wall of the furnace can enhance radiative heat transfer within the furnace body and effectively reduce energy consumption. The higher the emissivity of the infrared radiation coating, the more significant the energy-saving effect of the coating.

[0003] Infrared radiation coating materials are composed of an emitting base material, a binder, and some auxiliary additives. Among them, the emissivity of the coating mainly depends on the emissivity of the emitting base material. Spinel structure Mn-Fe-Co-Cu powder is used as the emitting base material of infrared radiation coating materials because of its high emissivity and relatively low raw material price. At present, Mn-Fe-Co-Cu emitting base material is usually prepared by high temperature calcination method. O2 The preparation method involves mixing four types of powders, including O3 and CuO, in a certain proportion, calcining at high temperature, and then cooling. However, this preparation method has certain limitations: first, the mechanical mixing of the mixed powders makes it difficult to control the uniformity of the resulting Mn-Fe-Co-Cu emitter powder; second, the spinel-structured Mn-Fe-Co-Cu emitter powder formed by high-temperature calcination has large grains, which reduces the emissivity to a certain extent. Summary of the Invention

[0004] The present invention aims to solve the problems of poor uniformity of the powder components and large grains of spinel structured Mn-Fe-Co-Cu emission base materials in the prior art. A core-shell structured infrared emission material and a preparation method thereof are proposed. The preparation method comprises modifying the SiO2 surface with amino groups and then adsorbing Mn 2+ 、Fe 3+ 、Co 2+ 、Cu 2+ The resulting material, a core-shell infrared emitting material, consists of a SiO2 core and an outer layer of Mn-Fe-Co-Cu spinel nanoparticles. This effectively addresses the issues of poor component uniformity and large grains in the spinel-structured Mn-Fe-Co-Cu emitter base material. Furthermore, the unique core-shell structure further increases the emissivity of the emitter base material.

[0005] The present invention is achieved by a method for preparing a core-shell structure infrared emitting material, comprising the following steps:

[0006] S1, mixing silica powder, anhydrous ethanol, and an aminosilane coupling agent, and heating and stirring to obtain a first mixed slurry;

[0007] S2, centrifuging the cooled first mixed slurry, and then drying the obtained centrifugal precipitate;

[0008] S3, the dried centrifugal precipitate and the 2+ 、Fe 3+ 、Co 2+ 、Cu 2+ and a nitrate mixed solution, and stirred for adsorption to obtain a second mixed slurry;

[0009] S4, filtering and washing the second mixed slurry with distilled water, and drying the washed solid powder;

[0010] S5. Place the dried solid powder into a muffle furnace, heat it from room temperature to a set temperature and calcine it at a constant temperature, and then cool it naturally to obtain a core-shell structure infrared emitting material with a SiO2 core and a Mn-Fe-Co-Cu spinel nanoparticle outer layer.

[0011] In the above technical solution, preferably, in step S1, the mass ratio of silica powder, anhydrous ethanol, and aminosilane coupling agent is 1:10-20:0.1-0.3; the silica powder is silica powder rich in hydroxyl groups on the surface, and the particle size is 0.5-5 μm; and the aminosilane coupling agent is a monoamino, diamino, or triaminosilane coupling agent.

[0012] In the above technical solution, preferably, in step S1, the heating temperature is 75-78° C. and the reaction time is 2-3 h.

[0013] In the above technical solution, preferably, in step S2, the centrifugal separation speed is 2000-3000 r / min, and the centrifugal time is 5-10 min; the drying temperature of the centrifugal precipitate is 80-130° C., and the drying time is 1-3 h.

[0014] In the above technical solution, preferably, in step S3, the mass ratio of the dried centrifugal precipitate to the nitrate mixed solution is 1:20-30, and the Mn in the nitrate mixed solution is 1:20-30. 2+ 、Fe 3+ 、Co 2+ 、Cu 2+ The concentrations are 0.2~0.6mol / L, 0.2~0.7mol / L, 0.1~0.3mol / L, and 0.5~0.3mol / L, respectively, and the stirring adsorption time is 1~6h.

[0015] In the above technical solution, preferably, in step S4, the washed solid powder is dried at a temperature of 100 to 150° C. and for a drying time of 6 to 12 hours.

[0016] In the above technical solution, preferably, in step S5, the heating rate of the muffle furnace is 1-5°C / min, the calcination temperature is 1000-1150°C, and the calcination time is 1-2h.

[0017] The formation mechanism of the present invention and the advantages and positive effects thereof are:

[0018] 1. The present invention controls the amount of modification of amino functional groups on the surface of SiO2 particles by adjusting the amount of aminosilane coupling agent added and the structure (monoamino, diamino or triamino), thereby regulating the Mn 2+ 、Fe 3+ 、Co 2+ 、Cu 2+ Therefore, the present invention can achieve controllable preparation of the density and thickness of the Mn-Fe-Co-Cu spinel nanoparticle shell layer on the surface of SiO2 particles, avoiding the problem of continuous growth of the Mn-Fe-Co-Cu spinel nanoparticle shell grains after calcination, thereby reducing the infrared emissivity.

[0019] 2. Compared with the direct use of MnO2, Fe2O3, C O2 O3 and CuO powder particles are used as raw materials for calcining to prepare Mn-Fe-Co-Cu spinel material. The present invention adopts a preparation method of first solution adsorption and then calcination. The formed Mn-Fe-Co-Cu spinel component is more uniform, and the generated CoFe2O4, MnFe2O4, CuFe2O4 and CuMn2O4 phase compositions can be determined by the adsorption of Mn in the solution. 2+ 、Fe 3+ 、Co 2+ 、Cu 2+ The ratio is controlled.

[0020] 3. The core-shell structure prepared by the present invention, in which the inner core is SiO2 and the outer layer is Mn-Fe-Co-Cu spinel nanoparticles, is conducive to improving the emissivity. Specifically, when the infrared energy light in the high-temperature kiln is projected onto the surface of the core-shell structure emitting base material, part of the infrared energy light will be absorbed and radiated by the spinel shell layer, and the other part of the infrared energy light will pass through the outer shell layer into the SiO2 inner core. At this time, the SiO2 inner core can reflect the transmitted infrared energy light back to the external spinel shell layer, so that the outer layer Mn-Fe-Co-Cu spinel nanoparticles form secondary absorption of the infrared energy light reflected back by the SiO2 inner core and generate secondary radiation, thereby achieving an improvement in the infrared emissivity of the emitting base material. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a scanning electron microscope image of the core-shell structure infrared emitting material powder prepared in Inventive Example 5;

[0022] Figure 2 For the traditional direct MnO2, Fe2O3, C O2 Scanning electron microscope characterization image of Mn-Fe-Co-Cu spinel powder obtained by mixing four powders of O3 and CuO and calcining them at high temperature. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] Example 1

[0025] A method for preparing a core-shell structure infrared emitting material comprises the following steps:

[0026] S1, mixing silica powder, anhydrous ethanol, and an aminosilane coupling agent, and heating and stirring to obtain a first mixed slurry;

[0027] S2, centrifuging the cooled first mixed slurry, and then drying the obtained centrifugal precipitate;

[0028] S3, the dried centrifugal precipitate and the 2+ 、Fe 3+ 、Co 2+ 、Cu 2+ and a nitrate mixed solution, and stirred for adsorption to obtain a second mixed slurry;

[0029] S4, filtering and washing the second mixed slurry with distilled water, and drying the washed solid powder;

[0030] S5. Place the dried solid powder into a muffle furnace, heat it from room temperature to a set temperature and calcine it at a constant temperature, and then cool it naturally to obtain a core-shell structure infrared emitting material with a SiO2 core and a Mn-Fe-Co-Cu spinel nanoparticle outer layer.

[0031] The specific implementation process of this embodiment is as follows:

[0032] S1. Add silica powder, anhydrous ethanol, and an aminosilane coupling agent in a mass ratio of 1:10:0.1 to a three-necked round-bottom flask and stir at 75°C for 3 hours to obtain a first mixed slurry. The silica powder is silica powder having a hydroxyl group-rich surface and a particle size of 0.5 μm, and the aminosilane coupling agent is triaminosilane coupling agent.

[0033] S2. Centrifuge the cooled first mixed slurry at a centrifugal separation speed of 2000 r / min for 10 min, and then place the obtained centrifugal precipitate in an oven at 80° C. and dry it for 3 h.

[0034] S3, the dried centrifugal precipitate was mixed with the nitrate mixed solution at a mass ratio of 1:20, and stirred for 1 hour to obtain a second mixed slurry. 2+ 、Fe 3+ 、Co 2+ 、Cu 2+ The concentrations were 0.2mol / L, 0.7mol / L, 0.1mol / L and 0.5mol / L respectively.

[0035] S4. The second mixed slurry was filtered and washed with distilled water, and the washed solid powder was placed in an oven at 100° C. and dried for 12 hours.

[0036] S5. Place the dried solid powder in a muffle furnace, heat it from room temperature to 1000°C at a heating rate of 1°C / min, and calcine it for 2 hours. Then cool it naturally to obtain a core-shell structure infrared emitting material with a SiO2 core and a Mn-Fe-Co-Cu spinel nanoparticle outer layer.

[0037] Example 2

[0038] A method for preparing a core-shell structured infrared emitting material is substantially the same as that of Example 1, except that the particle size of the silicon dioxide powder is 5 μm, and the aminosilane coupling agent is a bisaminosilane coupling agent.

[0039] Example 3

[0040] A method for preparing a core-shell structured infrared emitting material is substantially the same as that of Example 2, except that the cooled first mixed slurry is centrifuged at a centrifugal speed of 3000 r / min for 5 minutes, and the obtained centrifugal precipitate is dried in an oven at 130° C. for 1 hour.

[0041] Example 4

[0042] A method for preparing a core-shell structured infrared emitting material is substantially the same as that of Example 3, except that the dried centrifugal precipitate is mixed with a nitrate mixed solution at a mass ratio of 1:30.

[0043] Example 5

[0044] A method for preparing a core-shell structure infrared emitting material comprises the following steps:

[0045] S1. Add silica powder, anhydrous ethanol, and an aminosilane coupling agent in a mass ratio of 1:20:0.3 to a three-necked round-bottom flask and stir at 78°C for 2 hours to obtain a first mixed slurry. The silica powder is silica powder having a hydroxyl group-rich surface and a particle size of 0.8 μm, and the aminosilane coupling agent is a monoaminosilane coupling agent.

[0046] S2. Centrifuge the cooled first mixed slurry at a centrifugal separation speed of 2000 r / min for 10 min, and then place the obtained centrifugal precipitate in an oven at 80° C. and dry it for 3 h.

[0047] S3, the dried centrifugal precipitate was mixed with the nitrate mixed solution at a mass ratio of 1:30, and stirred for 1 hour to obtain a second mixed slurry. 2+ 、Fe 3+ 、Co 2+ 、Cu 2+ The concentrations were 0.2mol / L, 0.7mol / L, 0.1mol / L and 0.5mol / L respectively.

[0048] S4. The second mixed slurry was filtered and washed with distilled water, and the washed solid powder was placed in an oven at 100° C. and dried for 12 hours.

[0049] S5. Place the dried solid powder in a muffle furnace, heat it from room temperature to 1000°C at a heating rate of 1°C / min, and calcine it for 2 hours. Then cool it naturally to obtain a core-shell structure infrared emitting material with a SiO2 core and a Mn-Fe-Co-Cu spinel nanoparticle outer layer.

[0050] The core-shell structure infrared emitting material obtained in this embodiment was subjected to a scanning test. Figure 1 shown.

[0051] Example 6

[0052] A method for preparing a core-shell structure infrared emitting material is basically the same as that in Example 5. The difference is that the Mn 2+ 、Fe 3+ 、Co 2+ 、Cu 2+ The concentrations were 0.6mol / L, 0.2mol / L, 0.3mol / L, and 0.3mol / L, respectively.

[0053] Example 7

[0054] A method for preparing a core-shell structure infrared emitting material is substantially the same as that of Example 6, except that the dried centrifugal precipitate is stirred and adsorbed with a nitrate mixed solution for 6 hours.

[0055] Example 8

[0056] A method for preparing a core-shell structured infrared emitting material is substantially the same as that of Example 7, except that the washed solid powder is placed in an oven at 150° C. and dried for 6 h.

[0057] Example 9

[0058] A method for preparing a core-shell structured infrared emitting material is substantially the same as that of Example 8, except that the dried solid powder is placed in a muffle furnace and calcined at a heating rate of 5°C / min.

[0059] Example 10

[0060] A method for preparing a core-shell structured infrared emitting material is substantially the same as that of Example 9, except that the dried solid powder is placed in a muffle furnace and calcined at 1150° C. for 1 hour.

[0061] The spinel core-shell infrared emitting material powder obtained in Examples 1-10 was made into a coating, and its normal total emissivity was tested using the GBT 4653-1984 "General Technical Requirements for Infrared Radiation Coatings." The test results are shown in Table 1.

[0062] Table 1 Normal total emissivity test results of various embodiments

[0063]

[0064] The normal total emissivity test results for the samples in each example in Table 1 indicate that the Mn-Fe-Co-Cu spinel core-shell structure infrared emitting material powder prepared using the technical solution of the present invention has excellent infrared emissivity (>0.9). The emissivity value is related to preparation process parameters such as the precursor silica particle size, the type of aminosilane coupling agent, the ratio of the amino-functionalized precursor powder to the metal ion nitrate mixed solution, the ratio of each ion in the metal ion nitrate mixed solution, the metal ion stirring adsorption time, and the calcination crystallization temperature.

[0065] Traditionally, MnO2, Fe2O3, C O2 The scanning electron microscope characterization picture of Mn-Fe-Co-Cu spinel powder obtained by mixing O3 and CuO powders and calcining at high temperature is shown in the figure. Figure 2 As shown, Figure 2 It shows that MnO2, Fe2O3, C O2The Mn-Fe-Co-Cu spinel powder obtained by simply mixing O3 and CuO powders and then calcining at high temperature has poor size uniformity and a large particle size (300-1000nm), and a relatively low infrared emissivity (<0.9). The core-shell structure infrared emitting material powder prepared by the method of the present invention is as follows: Figure 1 As shown, Figure 1 The Mn-Fe-Co-Cu spinel particles on the surface of the resulting core-shell infrared emitting material powder are approximately 50 nm in size and are uniformly distributed throughout the outer SiO2 layer. Nanoparticle size increases infrared emissivity, resulting in a core-shell infrared emitting material powder prepared using this invention exhibiting high infrared emissivity.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a core-shell structure infrared emitting material, comprising the following steps: S1, mixing silica powder, anhydrous ethanol, and an aminosilane coupling agent, and heating and stirring to obtain a first mixed slurry; S2, centrifuging the cooled first mixed slurry, and then drying the obtained centrifugal precipitate; S3, the dried centrifugal precipitate and the 2+ 、Fe 3+ 、Co 2+ 、Cu 2+ and a nitrate mixed solution, and stirred for adsorption to obtain a second mixed slurry; S4, filtering and washing the second mixed slurry with distilled water, and drying the washed solid powder; S5. Place the dried solid powder into a muffle furnace, heat it from room temperature to a set temperature and calcine it at a constant temperature, and then cool it naturally to obtain a core-shell structure infrared emitting material with a SiO2 core and a Mn-Fe-Co-Cu spinel nanoparticle outer layer.

2. The method for preparing a core-shell structure infrared emitting material according to claim 1, wherein: In step S1, the mass ratio of silica powder, anhydrous ethanol, and aminosilane coupling agent is 1:10-20:0.1-0.3; the silica powder is silica powder rich in hydroxyl groups on the surface, and the particle size is 0.5-5 μm; the aminosilane coupling agent is a monoamino, diamino, or triaminosilane coupling agent.

3. The method for preparing a core-shell structure infrared emitting material according to claim 1, wherein: In step S1, the heating temperature is 75-78° C. and the reaction time is 2-3 hours.

4. The method for preparing a core-shell structure infrared emitting material according to claim 1, wherein: In step S2, the centrifugal separation speed is 2000-3000 r / min, and the centrifugal time is 5-10 min; the drying temperature of the centrifugal precipitate is 80-130° C., and the drying time is 1-3 h.

5. The method for preparing a core-shell structure infrared emitting material according to claim 1, wherein: In the step S3, the mass ratio of the dried centrifugal precipitate to the nitrate mixed solution is 1:20-30, and the Mn in the nitrate mixed solution is 1:20-30. 2+ 、Fe 3+ 、Co 2+ 、Cu 2+ The concentrations are 0.2~0.6mol / L, 0.2~0.7mol / L, 0.1~0.3mol / L, and 0.5~0.3mol / L, respectively, and the stirring adsorption time is 1~6h.

6. The method for preparing a core-shell structure infrared emitting material according to claim 1, wherein: In step S4, the washed solid powder is dried at a temperature of 100 to 150° C. for a time of 6 to 12 hours.

7. The method for preparing a core-shell structure infrared emitting material according to claim 1, wherein: In step S5, the heating rate of the muffle furnace is 1-5°C / min, the calcination temperature is 1000-1150°C, and the calcination time is 1-2 hours.

8. A core-shell structure infrared emitting material, characterized by: The core-shell structure infrared emitting material is prepared by the preparation method of any one of claims 1 to 7.

9. Use of the core-shell structure infrared emitting material according to claim 8, characterized in that: Used in high temperature industrial kilns.

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