Spinel ceramic material with high-temperature extinction, broadband and high emissivity as well as preparation method and application of spinel ceramic material

Abstract

The invention belongs to the technical field of optical ceramics and functional ceramic materials, and discloses a spinel ceramic material with high-temperature extinction and broadband high emissivity as well as a preparation method and application thereof. The chemical formula of the material is Cu (0.7-x) Ni (x) Cr (1.5) Mn (0.8-y) MyO4, M is Co and Fe, x is more than or equal to 0 and less than or equal to 0.5, y is more than or equal to 0 and less than or equal to 0.5, and different-valence or variable-valence metal elements (Ni, Co and Fe) and Mn are co-doped with copper-chromium spinel. The spectral emissivity of the ceramic material in the infrared band of 2.5-25 microns is gt; the emissivity spectrum curve is flat, the material has the characteristics of wide band, high emissivity and the like, and the emissivity of a coating prepared from the material is the spectral emissivity gt of the infrared band of 2.5-25 microns; and 0.95, the method has good application prospects in the fields of aerospace thermal control, aerospace craft thermal protection, industrial kiln energy saving, high-temperature extinction black bodies, optical camera extinction coatings and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical ceramics and functional ceramic materials, and particularly relates to a spinel ceramic material with high-temperature extinction and broadband high emissivity, a preparation method thereof, and an application thereof. Background Art

[0002] Spinel-type ceramic oxides have become the main candidate materials in the fields of spacecraft thermal control in high-temperature environments, energy conservation of industrial furnace linings, extinction blackbodies, and extinction coatings for optical cameras due to their high melting point, good oxidation resistance, high infrared emissivity, and easy doping and modification. Manganese-doped copper chromite spinel shows high emissivity potential, but its emissivity in the mid-infrared band is not high and it shows narrow-band emission characteristics, which severely limits its application. In the prior art, CN113233876 discloses a high-emissivity high-entropy ceramic material LaMgAl 11 O 19 and a preparation method and application thereof. The spectral emissivity of this material in the 3-5μm infrared band is >0.85. However, the emissivity performance of this material is not high enough, and the high-emissivity band is relatively narrow. In addition, CN105198394 discloses a cordierite-spinel ceramic material with high infrared emissivity and a preparation method thereof. The infrared emissivity of this material in the 1-22μm band is ≥0.86, and the infrared emissivity in the 3-5μm band is ≥0.70. Although it has a good performance in broadening the high-emissivity band, the emissivity in the short-wave band is relatively low.

[0003] According to Wien's displacement law, it is required that the spectral emissivity of the material in the 3-5μm infrared band at high temperature reaches above 0.90 to achieve better thermal control and energy-saving effects; at the same time, it is also very necessary to maintain high emissivity in the 2.5-25μm infrared band to enable the material to achieve better thermal management or extinction effects for different service temperatures, different working environments, and different application modes. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a spinel ceramic material with high-temperature extinction and broadband high emissivity. This material selects hetero-valent or variable-valent metal elements to co-dope copper chromite spinel with Mn. The spectral emissivity in the 2.5-25μm infrared band is >0.9, and the emissivity spectral curve is flat, with characteristics such as broadband high emissivity. The emissivity of the coating prepared with this material in the 2.5-25μm infrared band is >0.95, realizing the broadband extinction performance of the material, thus overcoming the deficiencies of the prior art.

[0005] The present invention also provides a method for preparing the above spinel ceramic material. The hetero-valent or variable-valent metal element and Mn co-doped copper-chromium spinel ceramic material prepared by the solid-phase reaction method has a spectral emissivity > 0.9 in the infrared band of 2.5 - 25 μm, and the emissivity spectral curve is flat, with characteristics such as high emissivity in a wide band. The emissivity of the coating prepared with this material is > 0.95 in the infrared band of 2.5 - 25 μm.

[0006] The present invention also provides the application of the above spinel ceramic material in high-temperature extinction and high-emissivity coatings, as well as a method for preparing the coating. The appearance of the coating is uniformly grayish-black, the coating is complete and continuous, without defects such as cracks, notches, and edge warping; the spectral emissivity in the infrared band of 2.5 - 25 μm is > 0.95, and it has good application prospects under normal temperature and high-temperature environments (800 - 1200 °C), and can be applied in fields such as aerospace thermal control, aerospace vehicle thermal protection, industrial furnace energy conservation, high-temperature extinction blackbody, and optical camera extinction coating.

[0007] The technical solution of the present invention is as follows:

[0008] The present invention provides a spinel ceramic material with high-temperature extinction and broadband high emissivity, and its chemical formula is Cu 0.7-x Ni x Cr 1.5 Mn 0.8-y M y O4, where M = Co, Fe, 0 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.5.

[0009] In an embodiment of the present invention, preferably, when x is 0, the chemical formula of the spinel ceramic material is Cu 0.7 Cr 1.5 Mn 0.8-y Co y O4, and y is 0.2 - 0.5. Further preferably, y is 0.4 or 0.5, that is, the chemical formulas of the spinel ceramic material are respectively Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5 O4, Cu 0.7 Cr 1.5 Mn 0.4 Fe 0.4 O4.

[0010] In an embodiment of the present invention, preferably, when y is 0, the chemical formula of the spinel ceramic material is Cu 0.7-x Ni x Cr 1.5 Mn 0.8O4, where x is 0.2 to 0.5. Further preferably, x is 0.4, that is, the chemical formula of the spinel ceramic material is Cu 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O 4。

[0011] The present invention also discloses a preparation method of the above spinel ceramic material with high-temperature extinction and broadband high emissivity, comprising the following steps: taking copper oxide, chromium oxide, manganese dioxide, and one of cobalt oxide, iron oxide or nickel oxide for ball milling and mixing, drying the mixed powder and then sintering it, the sintering temperature is 1150 to 1250 °C, the heating rate is 3 to 5 °C / min, and the holding time is 4 - 6 h to obtain a spinel ceramic material with high-temperature extinction and broadband high emissivity. Among them, the ball milling and mixing method is wet ball milling, and the medium used is anhydrous ethanol.

[0012] The ball milling speed is preferably 300 to 400 rpm, and the ball milling time is preferably 6 to 10 h. The present invention has no special limitation on the dosage of the anhydrous ethanol, and it can be smoothly ball milled according to the dosages well-known in the art.

[0013] The sintering temperature is more preferably 1200 °C, and the holding time is 4 h.

[0014] In an embodiment of the present invention, preferably, the purities of copper oxide, chromium oxide, manganese dioxide, cobalt oxide, iron oxide and nickel oxide are each independently ≥ 99%

[0015] The obtained spinel ceramic material with high-temperature extinction and broadband high emissivity is in powder form. For the convenience of testing the powder, in an embodiment of the present invention, preferably, it further includes cold pressing the spinel ceramic material to form a green body, and the green body is heat-insulated in stages to make the spinel ceramic material powder fully sintered to form a dense block, obtaining a single-phase product.

[0016] The present invention has no special limitation on the diameter and shape of the green body, and the green body can be prepared according to the diameters and shapes well-known in the art; in the embodiment of the present invention, the diameter of the green body is 30 mm and the shape is a cylinder.

[0017] In an embodiment of the present invention, preferably, the pressure for cold pressing in step (2) is 35 - 40 MPa, and the pressure holding time is 3 - 5 min. More preferably, the pressure for cold pressing is 38 MPa, and the pressure holding time is 4 min. The staged heat preservation includes: the calcination temperature in the first stage is 500 - 600 °C, and the heat preservation time is 1 - 2 h. More preferably, the calcination temperature in the first stage is 550 - 600 °C, and the heat preservation time is more preferably 1.5 - 2 h. The calcination temperature in the second stage is: 1400 - 1500 °C, and the heat preservation time is 4 - 6 h. Preferably, the calcination temperature in the second stage is 1430 - 1450 °C, and the heat preservation time is preferably 3.5 - 4 h. The heating rate from room temperature to the calcination temperature of the two stages is 3 - 5 °C / min. More preferably, it is 5 °C / min in the first stage and more preferably 4 °C / min in the second stage.

[0018] The present invention conducts sintering in a way of two-stage heat preservation with a gradually decreasing heating rate in each stage, which is beneficial to prolong the heating time of the sample, promote the uniform distribution of the internal temperature, and is more likely to obtain a single-phase product during heat preservation, making the surface of the prepared ceramic material free of microcracks and the phase pure. Moreover, the spectral emissivity in the infrared band of 2.5 - 25 μm is >0.9, and the emissivity spectral curve is flat, having the characteristics of high emissivity in a wide band, meeting the application requirements of spinel ceramics in fields such as aerospace thermal control, aerospace vehicle thermal protection, industrial furnace energy conservation, high-temperature extinction blackbody, and optical camera extinction coating.

[0019] The present invention also discloses the application of the above spinel ceramic material in high-temperature extinction and high-emissivity coatings, and the coatings can be applied in fields such as aerospace thermal control, aerospace vehicle thermal protection, industrial furnace energy conservation, high-temperature extinction blackbody, and optical camera extinction coating.

[0020] The present invention also discloses a preparation method of a coating with high-temperature extinction and high-emissivity, including the following steps: spraying the prepared doped spinel-type ceramic powder on the surface of a substrate coated with an MCrAlY (M is Co or Ni) bonding layer by atmospheric plasma spraying. First, spray the MCrAlY bonding layer on the surface of the substrate by atmospheric plasma. Spraying parameters: the main gas (Ar) flow rate is 95 - 105 SCFH, the auxiliary gas (H2) flow rate is 5 - 7.5 SCFH, and the power is 30 - 35 kW. Then, spray the above spinel ceramic material on the surface of the MCrAlY bonding layer by atmospheric plasma to obtain a coating with high-temperature extinction and high-emissivity. Spraying parameters: the main gas (Ar) flow rate is 92 - 107 SCFH, the auxiliary gas (H2) flow rate is 5 - 8.5 SCFH, and the power is 35 - 40 kW.

[0021] The present invention also discloses a preparation method of a coating with high-temperature extinction and high emissivity, comprising the following steps: spraying a high-temperature extinction and broadband high-emissivity spinel ceramic powder material on the surface of a substrate by a multi-stage continuous spraying method. First, spray a solution of aluminum diisopropoxyacetoacetate chelate, 1,2-propanediol and the above-mentioned spinel ceramic powder, which are mixed according to a mass ratio of 1:1:1, onto the substrate with a spray gun. After heating at 300 °C, then use a spray gun to spray a solution of TTIP, acetylacetone, isopropanol and the above-mentioned spinel ceramic material, which are mixed according to a solid-liquid mass ratio of 20:1, at a temperature of 300 °C. Finally, perform heat treatment, and the heat treatment process parameters are: the heating rate is 2-3 °C / min, the heat treatment temperature is 600-800 °C, and the holding time is 2-4 h, to obtain a coating with high-temperature extinction and high emissivity.

[0022] The coatings prepared by the above two coating preparation methods are both uniformly gray-black in appearance, the coatings are complete and continuous, without defects such as cracks, notches and edge warping; the spectral emissivity in the infrared band of 2.5-25 μm is >0.95; observing the metallographic structure of the coating, the area of the interface between the substrate and the bonding layer where sand grains are embedded is ≤5% of the total interface area, the porosity of the bonding layer is ≤5%, and the porosity of the high-emissivity ceramic coating is 5-20%.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] A spinel ceramic material of the present invention with high-temperature extinction and broadband high emissivity has the chemical formula Cu 0.7- x Ni x Cr 1.5 Mn 0.8-y M y O4, where M = Co, Fe, 0 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.5. By selecting hetero-valent or variable-valent metal elements for doping, the carrier concentration in the system is increased, which is beneficial to the absorption of infrared light by free carriers, thereby improving the spectral emissivity in the corresponding band; at the same time, the doping elements enter the crystal lattice, resulting in the generation of lattice distortion, which is beneficial to the absorption of lattice vibration; the introduction of doping elements increases the number of impurity energy levels between the valence band and the conduction band of the material, reduces the band gap width, and is beneficial to the electrons in the impurity energy levels to absorb the energy of infrared light and transition to the conduction band, thereby improving the emissivity. After testing, the ceramic material of the present invention has a spectral emissivity >0.9 in the infrared band of 2.5-25 μm, and the emissivity spectral curve is flat, having the characteristics of high emissivity in a wide band.

[0025] In addition, the present invention prepares copper chromite spinel co-doped with heterovalent or variable-valence metal elements (Ni, Co, Fe) and Mn by a solid-phase reaction method, and adopts a staged heat preservation process. First, it is heat-preserved in a lower temperature range for a certain time to fully remove the binder from the ceramic block, and then the temperature is raised to the calcination temperature of the target product for heat preservation to fully sinter the ceramic powder to form a dense block, obtaining a single-phase product. Only when the phase remains single can the emissivity of the material be stable during use, and there will be no situation where the emissivity suddenly changes due to the reaction between different phases. In addition, the single phase makes the internal structure of the material consistent, which is conducive to generating resonance between atoms to promote the absorption of infrared radiation, thereby improving the emissivity. The ceramic material prepared by the method of the present invention has no microcracks on the surface, the phase is pure, and the spectral emissivity in the 2.5-25 μm infrared band is >0.9, having good application prospects.

[0026] The present invention also provides a preparation process for high-temperature extinction and high-emissivity coatings, namely atmospheric plasma spraying and multi-stage continuous spraying method of a spray gun. The high-temperature extinction and high-emissivity coatings prepared by the two methods have a uniform gray-black or black appearance, the coatings are complete and continuous, without cracks, notches and edge warping defects. The spectral emissivity of the iron-manganese co-doped spinel component system high-temperature extinction and high-emissivity coating in the 2.5-25 μm infrared band is >0.95, and it has good application prospects at room temperature and high-temperature environments (800-1200 °C), and can be applied in the fields of aerospace thermal control, aerospace vehicle thermal protection, industrial furnace energy conservation, high-temperature extinction blackbody, optical camera extinction coating, etc. Brief Description of the Drawings

[0027] Figure 1 Infrared spectral emissivity of the Cu 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4 ceramic material in Example 1 of the present invention;

[0028] Figure 2 Infrared spectral emissivity of the Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5 O4 ceramic material in Example 4 of the present invention;

[0029] Figure 3 Infrared spectral emissivity of the Cu 0.7 Cr 1.5 Mn 0.4 Fe 0.4 O4 ceramic material in Example 7 of the present invention;

[0030] Figure 4The Cu prepared in Example 2, Example 3, Example 5, Example 6, Example 8 and Example 9 of the present invention 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4, Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5 O4, Cu 0.7 Cr 1.5 Mn 0.4 Fe 0.4 The infrared spectral emissivity of the high emissivity ceramic coating of O4. Detailed implementation manners

[0031] To make the above objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific implementation manners of the present invention will be given in conjunction with the accompanying drawings.

[0032] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific implementations disclosed below.

[0033] Example 1

[0034] Mix CuO powder (purity ≥ 99%), NiO powder (purity ≥ 99%), Cr2O3 powder (purity ≥ 99%) and MnO2 powder (purity ≥ 99%) according to the stoichiometric ratio of Cu 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4. Among them, the molar ratio of CuO powder, NiO powder, Cr2O3 powder and MnO2 powder is 0.3:0.4:0.75:0.8. Mix the obtained mixture with absolute ethanol and perform wet ball milling at a ball milling speed of 300 rpm for 6 h to obtain a light green mixed powder;

[0035] Put the light green mixed powder into a muffle furnace, heat it to 1200 °C at a rate of 5 °C / min, hold for 4 h, and cool with the furnace to obtain black Cu 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4 ceramic powder.

[0036] Load the black powder into a stainless steel mold and keep the pressure at 38 MPa for 4 min to obtain a cylindrical blank with a diameter of 30 mm;

[0037] Put the cylindrical blank into a muffle furnace, heat it at a rate of 5 °C / min to 600 °C, hold for 2 h (the first stage), then heat it at a rate of 4 °C / min to 1450 °C, hold for 4 h (the second stage), and cool it in the furnace to obtain Cu 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4 ceramic bulk material.

[0038] The Cu obtained in Example 1 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4 ceramic material powder and Cu 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4 ceramic bulk materials are consistent in phase, all being pure spinel phases, and also consistent in element types and ratios. For ease of testing, they are usually made into block materials. The same applies to Example 4 and Example 7.

[0039] Example 2

[0040] Mix CuO powder (purity ≥ 99%), NiO powder (purity ≥ 99%), Cr2O3 powder (purity ≥ 99%) and MnO2 powder (purity ≥ 99%) according to the stoichiometric ratio of Cu 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4, where the molar ratio of CuO powder, NiO powder, Cr2O3 powder, and MnO2 powder is 0.3:0.4:0.75:0.8. Mix the obtained mixture with absolute ethanol and carry out wet ball milling at a ball milling speed of 300 rpm for 6 h to obtain a light green mixed powder;

[0041] Put the light green mixed powder into a muffle furnace, heat it at a rate of 5 °C / min to 1200 °C, hold for 4 h, and cool it in the furnace to obtain black Cu 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4 ceramic material powder.

[0042] Clean and degrease the surface of the coating substrate, dehydrate it with absolute ethanol, and remove the oil stain with petroleum ether.

[0043] Use a pressure-fed sandblaster to perform sandblasting treatment on the skin surface; use white fused alumina sand with a mesh size of 36 - 80, a wind pressure of 0.3 - 0.5 MPa, a sandblasting angle of 50 - 80°, and a sandblasting distance of 70 - 130 mm to ensure that all surfaces to be sprayed are sandblasted. After sandblasting, the surface roughness of the substrate is not less than 0.5 μm.

[0044] Use atmospheric plasma spraying to prepare a bonding layer on the surface of the coating substrate. Process parameters: the main gas Ar flow rate is 100 SCFH, the auxiliary gas H2 flow rate is 6 SCFH, and the power is 35 kw. In this embodiment, the bonding layer material is NiCrA1Y (nickel-chromium-aluminum-yttrium).

[0045] Use atmospheric plasma spraying to prepare a high-emissivity ceramic coating on the surface of the bonding layer. Process parameters: the main gas Ar flow rate is 95 SCFH, the auxiliary gas H2 flow rate is 7.5 SCFH, and the power is 38 kw.

[0046] Example 3

[0047] Mix CuO powder (purity ≥ 99%), NiO powder (purity ≥ 99%), Cr2O3 powder (purity ≥ 99%), and MnO2 powder (purity ≥ 99%) according to the stoichiometric ratio of Cu 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4. Among them, the molar ratio of CuO powder, NiO powder, Cr2O3 powder, and MnO2 powder is 0.3:0.4:0.75:0.8. Mix the obtained mixture with absolute ethanol and perform wet ball milling at a ball milling speed of 300 rpm for 6 h to obtain a light green mixed powder;

[0048] Put the light green mixed powder into a muffle furnace, heat it to 1200 °C at a rate of 5 °C / min, hold for 4 h, and cool it with the furnace to obtain black Cu 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4 ceramic powder.

[0049] Use the multi-stage continuous spraying method to prepare a high-emissivity ceramic coating. First, use a spray gun to spray a solution of aluminum acetylacetonate diisopropoxide, 1,2-propanediol, and spinel ceramic material powder mixed in a mass ratio of 1:1:1 onto the substrate, and place the substrate on a heating table at 300 °C for heating; then use a spray gun to spray TTIP, acetylacetone, isopropanol, and Cu 0.3 Ni 0.4 Cr 1.5 Mn 0.8The solution of the O4 spinel ceramic material powder mixed according to the solid-liquid mass ratio of 20:1 is sprayed onto the first layer of coating; finally, the coating is placed in a muffle furnace for heat treatment, and the heat treatment process parameters are: the heating rate is 2 °C / min, the heat treatment temperature is 600 °C, and the holding time is 4 h.

[0050] Example 4

[0051] Mix CuO powder (purity ≥ 99%), Co2O3 powder (purity ≥ 99%), Cr2O3 powder (purity ≥ 99%), and MnO2 powder (purity ≥ 99%) according to the stoichiometric ratio of Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5 O4, where the molar ratio of CuO powder, Co2O3 powder, Cr2O3 powder, and MnO2 powder is 0.7:1.5:0.3:0.5. Mix the obtained mixture with absolute ethanol and perform wet ball milling at a ball milling speed of 300 rpm for 6 h to obtain a light green mixed powder;

[0052] Put the light green mixed powder into a muffle furnace, heat it to 1200 °C at a rate of 5 °C / min, hold for 4 h, and cool with the furnace to obtain black Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5 O4 ceramic powder.

[0053] Load the black powder into a stainless steel mold and keep the pressure at 38 MPa for 4 min to obtain a cylindrical blank with a diameter of 30 mm;

[0054] Put the cylindrical blank into a muffle furnace, heat it to 600 °C at a rate of 5 °C / min, hold for 2 h (the first stage), then heat it to 1450 °C at a rate of 4 °C / min, hold for 4 h (the second stage), and cool with the furnace to obtain Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5 O4 ceramic bulk material.

[0055] Example 5

[0056] Mix CuO powder (purity ≥ 99%), Co2O3 powder (purity ≥ 99%), Cr2O3 powder (purity ≥ 99%), and MnO2 powder (purity ≥ 99%) according to the stoichiometric ratio of Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5Ingredients are proportioned according to the stoichiometric ratio of CuCrMnCoO₄. Among them, the molar ratio of CuO powder, Co₂O₃ powder, Cr₂O₃ powder, and MnO₂ powder is 0.7:1.5:0.3:0.5. The obtained mixture is mixed with absolute ethanol and wet ball-milled at a ball-milling speed of 300 rpm for 6 hours to obtain a light green mixed powder;

[0057] Put the light green mixed powder into a muffle furnace, heat it to 1200 °C at a rate of 5 °C / min, hold for 4 hours, and cool with the furnace to obtain black Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5 CrMnCoO₄ ceramic material powder.

[0058] Clean and degrease the surface of the coating substrate, dehydrate it with absolute ethanol, and remove the oil stain with petroleum ether.

[0059] Use a pressure-fed sandblaster to sandblast the skin surface; use 36 - 80 mesh white corundum sand, the air pressure is 0.3 - 0.5 MPa, the sandblasting angle is 50 - 80°, and the sandblasting distance is 70 - 130 mm to ensure that all surfaces to be sprayed are sandblasted. After sandblasting, the surface roughness of the substrate is not less than 0.5 μm.

[0060] Use atmospheric plasma spraying to prepare a bond coat on the surface of the coating substrate. Process parameters: the main gas Ar flow rate is 100 SCFH, the auxiliary gas H₂ flow rate is 6 SCFH, and the power is 35 kw. In this example, the bond coat material is NiCrA1Y.

[0061] Use atmospheric plasma spraying to prepare a high-emissivity ceramic coating on the surface of the bond coat. Process parameters: the main gas Ar flow rate is 95 SCFH, the auxiliary gas H₂ flow rate is 7.5 SCFH, and the power is 38 kw.

[0062] Example 6

[0063] Mix CuO powder (purity ≥ 99%), Co₂O₃ powder (purity ≥ 99%), Cr₂O₃ powder (purity ≥ 99%), and MnO₂ powder (purity ≥ 99%) according to the stoichiometric ratio of Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5 CrMnCoO₄. Among them, the molar ratio of CuO powder, Co₂O₃ powder, Cr₂O₃ powder, and MnO₂ powder is 0.7:1.5:0.3:0.5. The obtained mixture is mixed with absolute ethanol and wet ball-milled at a ball-milling speed of 300 rpm for 6 hours to obtain a light green mixed powder;

[0064] Put the light green mixed powder into a muffle furnace, heat it to 1200 °C at a rate of 5 °C / min, keep it for 4 h, and cool it with the furnace to obtain black Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5 O4 ceramic material powder.

[0065] Prepare a high-emissivity ceramic coating by the multi-stage continuous spraying method. First, spray a solution in which aluminum acetylacetonate diisopropoxide, 1,2-propanediol and spinel ceramic material powder are mixed in a mass ratio of 1:1:1 onto the substrate with a spray gun, and place the substrate on a heating table at 300 °C for heating; then use a spray gun to spray a solution in which TTIP, acetylacetone, isopropanol and Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5 O4 spinel ceramic powder material are mixed in a solid-liquid mass ratio of 20:1 onto the first layer of coating; finally, put the coating into a muffle furnace for heat treatment, and the heat treatment process parameters are: the heating rate is 2 °C / min, the heat treatment temperature is 600 °C, and the holding time is 4 h.

[0066] Example 7

[0067] Mix CuO powder (purity ≥ 99%), Fe2O3 powder (purity ≥ 99%), Cr2O3 powder (purity ≥ 99%) and MnO2 powder (purity ≥ 99%) according to the stoichiometric ratio of Cu 0.7 Cr 1.5 Mn 0.4 Fe 0.4 O4, where the molar ratio of CuO powder, Fe2O3 powder, Cr2O3 powder, and MnO2 powder is 0.7:1.5:0.4:0.4. Mix the obtained mixture with anhydrous ethanol and perform wet ball milling at a ball milling speed of 300 rpm for 6 h to obtain a light red mixed powder;

[0068] Put the light red mixed powder into a muffle furnace, heat it to 1200 °C at a rate of 5 °C / min, keep it for 4 h, and cool it with the furnace to obtain black Cu 0.7 Cr 1.5 Mn 0.4 Fe 0.4 O4 ceramic powder.

[0069] Load the black powder into a stainless steel mold and keep the pressure at 38 MPa for 4 min to obtain a cylindrical blank with a diameter of 30 mm;

[0070] Put the cylindrical blank into a muffle furnace, heat it up to 600 °C at a rate of 5 °C / min, hold for 2 h (the first stage), then heat it up to 1450 °C at a rate of 4 °C / min, hold for 4 h (the second stage), and cool it in the furnace to obtain Cu 0.7 Cr 1.5 Mn 0.4 Fe 0.4 O4 ceramic bulk material.

[0071] Example 8

[0072] Mix CuO powder (purity ≥ 99%), Fe2O3 powder (purity ≥ 99%), Cr2O3 powder (purity ≥ 99%) and MnO2 powder (purity ≥ 99%) according to the stoichiometric ratio of Cu 0.7 Cr 1.5 Mn 0.4 Fe 0.4 O4. Among them, the molar ratio of CuO powder, Fe2O3 powder, Cr2O3 powder and MnO2 powder is 0.7:1.5:0.4:0.4. Mix the obtained mixture with absolute ethanol and carry out wet ball milling. The ball milling speed is 300 rpm and the ball milling time is 6 h to obtain a light red mixed powder;

[0073] Put the light red mixed powder into a muffle furnace, heat it up to 1200 °C at a rate of 5 °C / min, hold for 4 h, and cool it in the furnace to obtain black Cu 0.7 Cr 1.5 Mn 0.4 Fe 0.4 O4 ceramic material powder.

[0074] Clean and degrease the surface of the coating substrate, dehydrate it with absolute ethanol, and remove the oil stain with petroleum ether.

[0075] Use a pressure-fed sandblaster to sandblast the skin surface; use 36 - 80 mesh white corundum sand, the air pressure is 0.3 - 0.5 MPa, the sandblasting angle is 50 - 80°, and the sandblasting distance is 70 - 130 mm to ensure that all surfaces to be sprayed are sandblasted. After sandblasting, the surface roughness of the substrate is not less than 0.5 μm.

[0076] Prepare a bond coat on the surface of the coating substrate by atmospheric plasma spraying. Process parameters: the main gas Ar flow rate is 100 SCFH, the auxiliary gas H2 flow rate is 6 SCFH, and the power is 35 kw. In this example, the bond coat material is NiCrA1Y.

[0077] Prepare a high emissivity ceramic coating on the surface of the bond coat by atmospheric plasma spraying. Process parameters: the main gas Ar flow rate is 95 SCFH, the auxiliary gas H2 flow rate is 7.5 SCFH, and the power is 38 kw.

[0078] Example 9

[0079] Mix CuO powder (purity ≥ 99%), Fe2O3 powder (purity ≥ 99%), Cr2O3 powder (purity ≥ 99%) and MnO2 powder (purity ≥ 99%) according to the stoichiometric ratio of Cu 0.7 Cr 1.5 Mn 0.4 Fe 0.4 O4. Among them, the molar ratio of CuO powder, Fe2O3 powder, Cr2O3 powder, and MnO2 powder is 0.7:1.5:0.4:0.4. Mix the obtained mixture with absolute ethanol and carry out wet ball milling at a ball milling speed of 300 rpm for 6 h to obtain a light red mixed powder;

[0080] Put the light red mixed powder into a muffle furnace, heat it to 1200 °C at a rate of 5 °C / min, hold for 4 h, and cool with the furnace to obtain black Cu 0.7 Cr 1.5 Mn 0.4 Fe 0.4 O4 ceramic powder.

[0081] Prepare a high emissivity ceramic coating by multi-stage continuous spraying method. First, spray a solution of aluminum diisopropoxyacetoacetate chelate, 1,2-propanediol and spinel ceramic material powder mixed in a mass ratio of 1:1:1 onto the substrate with a spray gun, and place the substrate on a heating table at 300 °C for heating; then use a spray gun to spray a solution of TTIP, acetylacetone, isopropanol and Cu 0.7 Cr 1.5 Mn 0.4 Fe 0.4 O4 spinel ceramic material powder mixed in a solid-liquid mass ratio of 20:1 onto the first layer of coating; finally, put the coating into a muffle furnace for heat treatment, and the heat treatment process parameters are: heating rate is 2 °C / min, heat treatment temperature is 600 °C, and holding time is 4 h.

[0082] Characterization and performance testing

[0083] 1) Refer to the method described in GB / T4653-1984, and for the Cu 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4 ceramic materials, Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5 O4 ceramic materials and Cu 0.7 Cr 1.5 Mn0.4 Fe 0.4 The infrared spectral emissivity of the Fe3O4 ceramic material was tested, and the results are as follows Figures 1 to 3 shown. It can be seen from Figure 1 that the CuNiCrMnMnO4 ceramic material prepared in Example 1 has a spectral emissivity above 0.93 in the 2.5-14 μm infrared band, and the average spectral emissivity in the 2.5-25 μm infrared band reaches 0.9218; It can be seen from 0.3 Ni 0.4 Cr 1.5 Mn 0.8 that the CuCrMnCoO4 ceramic material prepared in Example 2 has a spectral emissivity above 0.94 in the 2.5-14 μm infrared band, and the average spectral emissivity in the 2.5-25 μm infrared band reaches 0.9354; It can be seen from Figure 2 that the CuCrMnFeO4 ceramic material prepared in Example 3 has a spectral emissivity above 0.95 in the 2.5-24 μm infrared band, and the average spectral emissivity in the 2.5-25 μm infrared band reaches 0.9444. 0.7 Cr 1.5 Mn 0.3 Co 0.5 2) The infrared spectral emissivity of the high emissivity ceramic coatings of CuNiCrMnO4, CuCrMnCoO4, and CuCrMnFeO4 prepared in Examples 2, 3, 5, 6, 8, and 9 was tested, and the results are as follows Figure 3 shown; It can be seen from 0.7 Cr 1.5 Mn 0.4 Fe 0.4 that the spectral emissivities of the 6 high emissivity ceramic coatings in the 2.5-25 μm infrared band are all above 0.9. Among them, the CuCrMnFeO4 prepared in Examples 8 and 9

[0084] 2) The infrared spectral emissivity of the high emissivity ceramic coatings of CuNiCrMnO4, CuCrMnCoO4, and CuCrMnFeO4 prepared in Examples 2, 3, 5, 6, 8, and 9 was tested, and the results are as follows 0.3 Ni 0.4 Cr 1.5 Mn 0.8 O4, Cu 0.7 Cr 1.5 Mn 0.3 Co 0.5 O4, Cu 0.7 Cr 1.5 Mn 0.4 Fe 0.4 O4 high emissivity ceramic coatings were tested for infrared spectral emissivity, and the results are as follows Figure 4 shown; It can be seen from Figure 4 that the spectral emissivities of the 6 high emissivity ceramic coatings in the 2.5-25 μm infrared band are all above 0.9. Among them, the CuCrMnFeO4 prepared in Examples 8 and 9 0.7 Cr 1.5 Mn 0.4 Fe 0.4The spectral emissivity of the O4 high-emissivity ceramic coating is above 0.95 in the infrared band of 2.5 - 25 μm. The metallographic structure of the high-emissivity ceramic coating in Example 8 was observed. The area of sand grain inlay at the coating substrate surface / adhesive layer interface is 3.1% of the total interface area, the porosity of the adhesive layer is 4.6%, and the porosity of the high-emissivity ceramic coating is 9.7%.

[0085] In the present invention, hetero-valent or variable-valent metal elements (Ni, Co, Fe) are selected to co-dope copper chromite spinel. Nickel element is selected to dope at the A site of the spinel. The reason is that Ni 2+ is similar in radius to Cu 2+ and Cr 3+ , and it is easy to be doped into the lattice. Iron element and cobalt element are selected to dope at the B site of the spinel. The reason is that manganese ions and cobalt ions are prone to octahedral super-exchange interaction. At the same time, multi-valent iron ions can enter the tetrahedral or octahedral structure, reducing the band gap of the material and increasing the ion valence states, which is beneficial to the electron transition and carrier absorption of the material. By selecting hetero-valent or variable-valent metal elements for doping, the carrier concentration in the system is increased, which is beneficial to the absorption of infrared light by free carriers, and thus the spectral emissivity in the corresponding band is improved; at the same time, the doped elements enter the lattice, resulting in lattice distortion, which is beneficial to lattice vibration absorption; the introduction of doped elements increases the number of impurity energy levels between the valence band and the conduction band of the material, reducing the band gap width, which is beneficial to the electrons in the impurity energy levels to absorb the energy of infrared light and transition to the conduction band, thereby improving the emissivity. The ceramic material provided by the present invention has a spectral emissivity > 0.9 in the infrared band of 2.5 - 25 μm and the emissivity spectral curve is flat, featuring high emissivity in a wide band. At the same time, the high-temperature extinction and broadband high-emissivity spinel ceramic material powder of the present invention can be used to prepare high-temperature extinction high-emissivity coatings by methods such as atmospheric plasma spraying, multi-stage continuous spraying of spray guns, and screen printing. The spectral emissivity of the iron-manganese co-doped spinel component system high-temperature extinction high-emissivity coating is > 0.95 in the infrared band of 2.5 - 25 μm, and it has good application prospects at room temperature and high-temperature environments (800 - 1200 °C).

[0086] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all details in detail, nor limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A spinel ceramic material with high-temperature extinction and broadband high emissivity, characterized in that, Its chemical formula is Cu 0.7-x Ni x Cr 1.5 Mn 0.8-y M y O4, where M = Co, Fe, 0 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.

5.

2. The spinel ceramic material with high-temperature extinction and broadband high emissivity according to claim 1, characterized in that, When x is 0, the chemical formula of the spinel ceramic material is Cu 0.7 Cr 1.5 Mn 0.8-y Co y O4 or Cu 0.7 Cr 1.5 Mn 0.8- y Fe y O4, and y is 0.2 to 0.

5.

3. The spinel ceramic material with high-temperature extinction and broadband high emissivity according to claim 1, characterized in that, When y is 0, the chemical formula of the spinel ceramic material is Cu 0.7-x Ni x Cr 1.5 Mn 0.8 O4, where x is from 0.2 to 0.

5.

4. A preparation method of a spinel ceramic material with high-temperature extinction and broadband high emissivity as described in any one of claims 1 to 3, characterized in that, It includes the following steps: Take copper oxide, chromium oxide, manganese dioxide, and one of cobalt oxide, iron oxide or nickel oxide for ball milling and mixing. The mixed powder is dried and then sintered. The sintering temperature is 1150 - 1250 °C, the heating rate is 3 - 5 °C / min, and the holding time is 4 - 6 h to obtain a spinel ceramic material with high-temperature extinction and broadband high emissivity. Among them, the ball milling and mixing method is wet ball milling, and the medium used is anhydrous ethanol.

5. The preparation method of the spinel ceramic material with high-temperature extinction and broadband high emissivity according to claim 4, characterized in that, The purities of the copper oxide, chromium oxide, manganese dioxide, cobalt oxide, iron oxide and nickel oxide are all ≥99% independently.

6. The preparation method of the spinel ceramic material with high-temperature extinction and broadband high emissivity according to claim 4, characterized in that, It also includes cold-pressing the spinel ceramic material to form a green body, and the green body is heat-preserved in stages so that the spinel ceramic material powder is fully sintered to form a dense block to obtain a single-phase product.

7. The preparation method of the spinel ceramic material with high-temperature extinction and broadband high emissivity according to claim 6, wherein the pressure for cold pressing and forming is 35 to 40 MPa, and the pressure holding time is 3 to 5 minutes; the staged heat preservation includes: The calcination temperature in the first stage is 500 - 600 °C, and the holding time is 1 - 2 h. The calcination temperature in the second stage is: 1400 - 1500 °C, and the holding time is 4 - 6 h. The heating rates in both stages are 3 - 5 °C / min.

8. Application of the spinel ceramic material according to any one of claims 1 - 3 in high-temperature extinction and high-emissivity coatings.

9. A preparation method of a coating with high-temperature extinction and high emissivity, characterized in that, It includes the following steps: First, spray an MCrAlY bonding layer on the substrate surface by atmospheric plasma. Spraying parameters: main gas (Ar) flow rate 95 - 105 SCFH, auxiliary gas (H2) flow rate 5 - 7.5 SCFH, power 30 - 35 kW; then spray the spinel ceramic material according to any one of claims 1 - 3 on the surface of the MCrAlY bonding layer by atmospheric plasma to obtain a high-temperature extinction and high-emissivity coating. Spraying parameters: main gas (Ar) flow rate 92 - 107 SCFH, auxiliary gas (H2) flow rate 5 - 8.5 SCFH, power 35 - 40 kW.

10. A preparation method of a coating with high-temperature extinction and high emissivity, characterized in that, It includes the following steps: First, spray a solution of aluminum diisopropoxyacetoacetate chelate, 1,2-propanediol and the spinel ceramic material according to any one of claims 1 - 3, which are mixed in a mass ratio of 1:1:1, onto the substrate with a spray gun. After heating at 300 °C, then spray a solution of TTIP, acetylacetone, isopropanol and the spinel ceramic material according to any one of claims 1 - 3, which are mixed in a solid-liquid mass ratio of 20:1, with a spray gun at a temperature of 300 °C; finally, perform heat treatment. Heat treatment process parameters: heating rate is 2 - 3 °C / min, heat treatment temperature is 600 - 800 °C, and holding time is 2 - 4 h to obtain a high-temperature extinction and high-emissivity coating.

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