Black alumina-based ceramic powder for plasma spraying and preparation method thereof

Abstract

The invention discloses black alumina-based ceramic powder for plasma spraying and a preparation method of the black alumina-based ceramic powder, and relates to the technical field of ceramic material preparation. When the black aluminum oxide-based ceramic powder for plasma spraying is prepared, firstly, aluminum oxide, titanium dioxide and a reducing agent are subjected to electric melting under the protective atmosphere to form a uniform melt, the melt is subjected to double-pulse atomization to form liquid drops, the liquid drops are cooled under the protective atmosphere, and the black aluminum oxide-based ceramic powder for plasma spraying is prepared. The black alumina-based ceramic powder for plasma spraying prepared by the invention is stable, uniform in color, bimodal in particle size distribution, and high in sphericity degree of the powder.

Description

Technical Field

[0001] The present invention belongs to the field of ceramic material preparation, and is particularly applicable to the preparation of high-performance ceramic coatings in plasma spraying processes. Specifically, it relates to a black alumina-based ceramic powder for plasma spraying and a preparation method thereof. Background Art

[0002] Semiconductor integrated circuits have obvious photosensitivity. Due to its unique light-shielding property, black alumina ceramics are widely used in fields such as the encapsulation housings of integrated circuits and the lining plates of digital tubes. As an important surface treatment technology, plasma spraying technology is widely used in the preparation of coatings for materials such as metals and ceramics. During the plasma spraying process, the properties of the sprayed powder directly affect the quality and performance of the coating. Black alumina-based ceramic powders have become one of the important materials for plasma spraying coatings due to their excellent properties such as high temperature resistance, corrosion resistance, and wear resistance. Commonly used coloring oxides for making black ceramics are: Fe 2 O 3 , CoO, NiO, Cr 2 O 3 , MnO, TiO 2 , V 2 O 5 etc.

[0003] Currently, the preparation of black alumina at home and abroad generally adopts the one-step synthesis method and the two-step synthesis method. The one-step synthesis method is to directly prepare black alumina according to a certain ratio and process with alumina, coloring oxide, and flux. The two-step synthesis method is to first synthesize black pigment with some metal oxides, and then prepare black alumina according to a certain ratio and process with black pigment, flux, and alumina. Zhang Xiaofeng used Al 2 O 3 , Fe 2 O 3 , CoO, NiO, MnO 2 , and talc as raw materials, and prepared black alumina ceramics by ball milling, drying, tabletting, and sintering using the one-step synthesis method. Using Fe 2 O 3 , CoO, NiO, MnO 2 as raw materials, first synthesized Fe-Co-Ni-Mn series black pigment, and then used pigment, alumina, and talc as raw materials to prepare black alumina ceramics by sintering method (Zhang Xiaofeng, China Ceramic Industry, 2010). Xu Lihua used ultrafine α-alumina powder as the main raw material, added appropriate amounts of transition metal oxides and different amounts of TiO 2 powder, and prepared black Al 2 O 3Ceramics (Xu Lihua, Jiangsu Ceramics, 2011). CN107406328 discloses a black alumina ceramic powder, which consists of alumina powder, a pigment containing Fe 2 O 3 , NiO, MnO 2 and Co 2 O 3 and additives selected from SiO 2 , TiO 2 , La 2 O 3 and their combinations. CN102659392 discloses a preparation method of calcined alumina for black ceramics, which is prepared by mixing activated alumina with a salt solution of black oxide, drying, calcining and then grinding. The above-mentioned black ceramics and powders are all prepared by mixing alumina with spinel-based black oxide pigments, and the uniformity of the pigments and alumina powders is limited to a certain extent. Moreover, the ceramic powders prepared by sintering and grinding are polygonal and granular, the surface of the powders is rough, and the fluidity is poor.

[0004] The invention patent CN113830807 discloses a preparation method of intrinsic black alumina powder, which uses alumina, alkali metal and alkaline earth metal hydrides as reducing agents, and alkali metal chlorides and alkali metal nitrates as molten salts. This method requires washing with water and pickling to remove the molten salts and reducing agents, and subsequent wastewater needs to be recycled or treated, which has certain environmental risks.

[0005] In the prior art, the preparation of black alumina-based ceramic powders mainly relies on traditional sintering, crushing, grinding or chemical synthesis methods. However, these methods have certain deficiencies in terms of powder uniformity, particle size distribution and powder morphology, and it is difficult to meet the high requirements for powder quality and spraying effect in plasma spraying. Summary of the Invention

[0006] The purpose of the present invention is to provide a black alumina-based ceramic powder for plasma spraying and its preparation method to solve the problems existing in the prior art.

[0007] To solve the above technical problems, the present invention provides the following technical solutions:

[0008] A preparation method of a black alumina-based ceramic powder for plasma spraying, the preparation method is as follows:

[0009] (1) Weigh alumina, titanium oxide, and reducing agent according to a mass ratio of 100:(60 - 90):(0.2 - 2);

[0010] (2) Form a melt through an electrofusion process under the protection of a protective gas;

[0011] (3) The melt is atomized into droplets by double-pulse atomization and cooled under the protection of a protective gas to obtain black alumina-based ceramic powder for plasma spraying.

[0012] As an optimization, the protective gas is one of nitrogen, argon, ammonia, and hydrogen / argon mixture.

[0013] As an optimization, in step (1), the reducing agent is one or more of aluminum, titanium, and titanium-aluminum alloy; the mass fraction of aluminum oxide in the alumina is ≥99.0%; the mass fraction of titanium dioxide in the titanium oxide is ≥99.0%.

[0014] As an optimization, the electrofusion process in step (2) is: electrofusion is carried out in a plasma arc furnace; the temperature of the melt is 1900 - 2200 °C.

[0015] As an optimization, the atomization method in step (3) is one of centrifugal atomization, jet atomization, and ultrasonic atomization; the double-pulse atomization refers to the alternate pulse atomization of two different atomization process parameters.

[0016] As an optimization, the particle size of the black alumina-based ceramic powder for plasma spraying shows a bimodal distribution.

[0017] As an optimization, the black alumina-based ceramic powder for plasma spraying is spherical, and the sphericity is ≥90%.

[0018] The present invention also provides a black alumina-based ceramic powder for plasma spraying prepared by the preparation method of the black alumina-based ceramic powder for plasma spraying according to the above.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0020] (1) Atmosphere control regulates the valence state of titanium: By precisely controlling the reaction atmosphere (such as reducing atmosphere or inert atmosphere) and introducing an appropriate amount of reducing agent, the valence state and the nuclear outer electron structure of titanium element can be regulated in-situ. The valence state change of titanium element in the alumina matrix will significantly affect the color and optical properties of the material. Through this regulation, a stable black titanium oxide or titanium-doped alumina structure can be formed, thereby ensuring the color uniformity and stability of the alumina-based black ceramic powder.

[0021] (2) Achieving bimodal distribution of powder through pulsed atomization: By using pulsed atomization technology, the particle size distribution of powder particles can be precisely controlled to generate powder particles with bimodal distribution. Bimodal distribution means that there are two different particle size ranges of particles in the powder, usually composed of larger particles and smaller particles. This optimization of particle grading can effectively improve the densification and bonding strength of the coating. The larger particles play a role of skeleton support in the coating, while the smaller particles fill the voids between the large particles, thus improving the density and mechanical properties of the coating. By precisely controlling the particle size ratio and proportion of the two types of particles in the bimodal distribution, the performance of the coating can be significantly improved, solving the problems of poor coating densification and high porosity caused by the single particle size of traditional unimodal distribution powder during the spraying process.

[0022] (3) Direct atomization and cooling of high-temperature melt: Through the technology of direct atomization and cooling of high-temperature melt, the molten ceramic material can be rapidly atomized into tiny droplets under the action of high-speed air flow or centrifugal force, and solidified into spherical particles during the cooling process. This method can significantly improve the sphericity of the powder, and improve the fluidity and packing density of the powder. Due to the irregular shape or rough surface of traditional powder, problems such as poor fluidity and uneven transportation are likely to occur during the spraying process, affecting the stability of the spraying process and the coating quality. While spherical powder has better fluidity and uniformity, which can ensure the stable transportation and uniform deposition of the powder during the spraying process, thus improving the uniformity and densification of the coating. In addition, spherical powder also has higher deposition efficiency and lower porosity during the spraying process, further enhancing the performance and service life of the coating.

[0023] Through the comprehensive application of the above technologies, not only can the color uniformity and stability of alumina-based black ceramic powder be regulated, but also the particle grading optimization and fluidity of the powder can be significantly improved, thus solving the problems of poor coating densification, high porosity, and insufficient fluidity existing in the traditional spraying process. The application of these technologies provides reliable technical support for the preparation of high-performance ceramic coatings, and is widely used in fields such as aerospace, energy, electronics, and mechanical manufacturing, meeting the high requirements for material color, performance, and process stability. Description of the Drawings

[0024] Figure 1 Scanning electron microscope image of the black alumina-based ceramic powder for plasma spraying prepared in Example 1.

[0025] Figure 2 Particle size distribution diagram of the black alumina-based ceramic powder for plasma spraying prepared in Example 1. Detailed Implementation Modes

[0026] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] Embodiment 1:

[0028] A preparation method of black alumina-based ceramic powder for plasma spraying, the preparation method is as follows:

[0029] (1) Weigh alumina, titanium oxide, and reducing agent according to a mass ratio of 100:60:0.2; the reducing agent is aluminum; the mass fraction of aluminum oxide in the alumina is ≥99.0%; the mass fraction of titanium dioxide in the titanium oxide is ≥99.0%;

[0030] (2) Form a melt through an electrofusion process under nitrogen protection: perform electrofusion in a plasma arc furnace; the melt temperature is 2200 °C, and the plasma arc model is KPDH-800;

[0031] (3) Atomize the melt into droplets through double-pulse atomization and cool it under nitrogen protection to obtain black alumina-based ceramic powder for plasma spraying; the atomization method is one of centrifugal atomization, jet atomization, and ultrasonic atomization; the double-pulse atomization refers to the alternating pulse atomization of two different atomization process parameters; the centrifugal atomization process parameters are: two process parameters are adopted and alternated, and the process parameters are as follows: the rotation speed of the rotating disk is 24000 r / min, and the running time is 10 s; the rotation speed of the rotating disk is 20000 r / min; the running time is 10 s.

[0032] The particle size of the black alumina-based ceramic powder for plasma spraying prepared in Embodiment 1 shows a bimodal distribution. The particle size range of the large-particle-size powder is 10 μm to 80 μm, and the particle size range of the small-particle-size powder is 1 μm to 10 μm; the ratio of the large particle size to the small particle size is 3.2:1.

[0033] Embodiment 2:

[0034] A preparation method of black alumina-based ceramic powder for plasma spraying, the preparation method is as follows:

[0035] (1) Weigh alumina, titanium oxide, and reducing agent according to a mass ratio of 100:60:0.2; the reducing agent is aluminum; the mass fraction of aluminum oxide in the alumina is ≥99.0%; the mass fraction of titanium dioxide in the titanium oxide is ≥99.0%;

[0036] (2) Form a melt through an electrofusion process under nitrogen protection: Perform electrofusion in a plasma arc furnace; the temperature of the melt is 2200 °C, and the plasma arc model is KPDH-800;

[0037] (3) Form droplets by double-pulse atomization of the melt, and cool under nitrogen protection to obtain black alumina-based ceramic powder for plasma spraying; the atomization method is jet atomization; the double-pulse atomization refers to the alternate pulsed atomization of two different atomization process parameters; the jet atomization process parameters are as follows: Two process parameters are adopted and alternated. The process parameters are as follows: the atomization apex angle is 45 °C, the gas pressure is 0.5 MPa, and the running time is 10 s; the atomization apex angle is 60 °C, the gas pressure is 0.5 MP, and the running time is 10 s.

[0038] Example 3:

[0039] A preparation method of black alumina-based ceramic powder for plasma spraying, the preparation method is as follows:

[0040] (1) Weigh alumina, titanium oxide, and reducing agent according to a mass ratio of 100:60:0.2; the reducing agent is titanium; the mass fraction of aluminum trioxide in the alumina is ≥99.0%; the mass fraction of titanium dioxide in the titanium oxide is ≥99.0%;

[0041] (2) Form a melt through an electrofusion process under nitrogen protection: Perform electrofusion in a plasma arc furnace; the temperature of the melt is 2200 °C, and the plasma arc model is KPDH-800;

[0042] (3) Form droplets by double-pulse atomization of the melt, and cool under nitrogen protection to obtain black alumina-based ceramic powder for plasma spraying; the atomization method is ultrasonic atomization; the double-pulse atomization refers to the alternate pulsed atomization of two different atomization process parameters; the ultrasonic atomization process parameters are as follows: Two process parameters are adopted and alternated. The process parameters are as follows: the atomization medium is argon, the gas atomization pressure is 6.8 MPa, the jet angle is 45 °C, the frequency of the ultrasonic gas atomizer is 80 kHz, and the running time is 10 s; the atomization medium is argon, the gas atomization pressure is 6.8 MPa, the jet angle is 45 °C, the frequency of the ultrasonic gas atomizer is 160 kHz, and the running time is 10 s; the running time is 10 s.

[0043] Example 4:

[0044] A preparation method of black alumina-based ceramic powder for plasma spraying, the preparation method is as follows:

[0045] (1) Weigh alumina, titanium oxide, and reducing agent according to a mass ratio of 100:90:2; the reducing agent is titanium; the mass fraction of aluminum oxide in the alumina is ≥99.0%; the mass fraction of titanium dioxide in the titanium oxide is ≥99.0%.

[0046] (2) Under the protection of nitrogen, argon, ammonia, or hydrogen / argon mixture, form a melt through an electrofusion process: conduct electrofusion in a plasma arc furnace; the melt temperature is 1900 °C, and the plasma arc model is KPDH-800.

[0047] (3) Form droplets by double-pulse atomization of the melt, and cool under the protection of nitrogen to obtain black alumina-based ceramic powder for plasma spraying; the atomization method is one of centrifugal atomization, jet atomization, and ultrasonic atomization; the double-pulse atomization means that two different atomization process parameters are alternately pulsed for atomization; the centrifugal atomization process parameters are as follows: two process parameters are adopted and alternately carried out. The process parameters are as follows: the rotational speed of the rotating disk is 24000 r / min, and the running time is 10 s; the rotational speed of the rotating disk is 20000 r / min; the running time is 10 s.

[0048] Example 5:

[0049] A preparation method of black alumina-based ceramic powder for plasma spraying, and the preparation method is as follows:

[0050] (1) Weigh alumina, titanium oxide, and reducing agent according to a mass ratio of 100:90:2; the reducing agent is aluminum; the mass fraction of aluminum oxide in the alumina is ≥99.0%; the mass fraction of titanium dioxide in the titanium oxide is ≥99.0%.

[0051] (2) Under the protection of nitrogen, form a melt through an electrofusion process: conduct electrofusion in a plasma arc furnace; the melt temperature is 1900 °C, and the plasma arc model is KPDH-800.

[0052] (3) Form droplets by double-pulse atomization of the melt, and cool under the protection of nitrogen to obtain black alumina-based ceramic powder for plasma spraying; the atomization method is jet atomization; the double-pulse atomization means that two different atomization process parameters are alternately pulsed for atomization; the jet atomization process parameters are as follows: two process parameters are adopted and alternately carried out. The process parameters are as follows: the atomization apex angle is 45 °C, the gas pressure is 0.5 MPa, and the running time is 10 s; the atomization apex angle is 60 °C, the gas pressure is 0.5 MP, and the running time is 10 s.

[0053] Example 6:

[0054] A preparation method of black alumina-based ceramic powder for plasma spraying, and the preparation method is as follows:

[0055] (1) Weigh alumina, titanium oxide, and reducing agent according to a mass ratio of 100:90:2; the reducing agent is aluminum; the mass fraction of aluminum oxide in the alumina is ≥99.0%; the mass fraction of titanium dioxide in the titanium oxide is ≥99.0%.

[0056] (2) Form a melt through an electrofusion process under nitrogen protection: conduct electrofusion in a plasma arc furnace; the temperature of the melt is 1900 °C, and the plasma arc model is KPDH-800.

[0057] (3) Atomize the melt into droplets through double-pulse atomization and cool it under nitrogen protection to obtain black alumina-based ceramic powder for plasma spraying; the atomization method is ultrasonic atomization; the double-pulse atomization refers to the alternate pulse atomization of two different atomization process parameters; the ultrasonic atomization process parameters are as follows: two process parameters are adopted and alternated. The process parameters are as follows: the atomization medium is argon, the gas atomization pressure is 6.8 MPa, the jet angle is 45 °C, the frequency of the ultrasonic gas atomizer is 80 kHz, and the operation time is 10 s; the atomization medium is argon, the gas atomization pressure is 6.8 MPa, the jet angle is 45 °C, the frequency of the ultrasonic gas atomizer is 160 kHz, and the operation time is 10 s; the operation time is 10 s.

[0058] Comparative Example 1:

[0059] A method for preparing black alumina-based ceramic powder for plasma spraying, the preparation method is as follows:

[0060] (1) Weigh alumina, titanium oxide, and reducing agent according to a mass ratio of 100:60:0.2; the reducing agent is aluminum; the mass fraction of aluminum oxide in the alumina is ≥99.0%; the mass fraction of titanium dioxide in the titanium oxide is ≥99.0%.

[0061] (2) Form a melt through an electrofusion process under nitrogen protection: conduct electrofusion in a plasma arc furnace; the temperature of the melt is 2200 °C, and the plasma arc model is KPDH-800.

[0062] (3) Atomize the melt into droplets and cool it under nitrogen protection to obtain black alumina-based ceramic powder for plasma spraying; the atomization method is centrifugal atomization; the centrifugal atomization process parameters are as follows: two process parameters are adopted and alternated. The process parameters are as follows: the rotational speed of the rotating disk is 24000 r / min.

[0063] Comparative Example 2:

[0064] A method for preparing black alumina-based ceramic powder for plasma spraying, the preparation method is as follows:

[0065] (1) Weigh alumina, titanium oxide, and reducing agent according to a mass ratio of 100:60:0.2; the reducing agent is aluminum; the mass fraction of aluminum oxide in the alumina is ≥99.0%; the mass fraction of titanium dioxide in the titanium oxide is ≥99.0%;

[0066] (2) Form a melt through an electrofusion process under nitrogen protection: perform electrofusion in a plasma arc furnace; the melt temperature is 2200 °C, and the plasma arc model is KPDH-800;

[0067] (3) Atomize the melt to form droplets and cool them under nitrogen protection to obtain black alumina-based ceramic powder for plasma spraying; the atomization method is jet atomization; the process parameters of the jet atomization are: the atomization apex angle is 45 °C, and the gas pressure is 0.5 MPa.

[0068] Comparative Example 3:

[0069] A method for preparing black alumina-based ceramic powder for plasma spraying, the preparation method is as follows:

[0070] (1) Weigh alumina, titanium oxide, and reducing agent according to a mass ratio of 100:60:0.2; the reducing agent is aluminum; the mass fraction of aluminum oxide in the alumina is ≥99.0%; the mass fraction of titanium dioxide in the titanium oxide is ≥99.0%;

[0071] (2) Form a melt through an electrofusion process under nitrogen protection: perform electrofusion in a plasma arc furnace; the melt temperature is 2200 °C, and the plasma arc model is KPDH-800;

[0072] (3) Atomize the melt to form droplets and cool them under nitrogen protection to obtain black alumina-based ceramic powder for plasma spraying; the atomization method is ultrasonic atomization; the process parameters of the ultrasonic atomization are: the atomization medium is argon, the gas atomization pressure is 6.8 MPa, the jet angle is 45 °C, and the frequency of the ultrasonic gas atomizer is 80 kHz.

[0073] Test Example 1:

[0074] Test of antioxidant performance:

[0075] Test method: The ceramic powders prepared in the examples and comparative examples were used to prepare coatings with the MF-P1000 atmospheric plasma spraying system produced by GTV Company, Germany; the coating substrate was made of 304 stainless steel. First, the substrate was degreased and derusted to ensure that the surface of the substrate was free of contamination, and then the substrate was sandblasted with corundum particles; the spraying parameters were as follows: the current was 600 A, the voltage was 70 V, the spraying distance was 110 mm, the helium gas flow rate was 40 L / min, the hydrogen gas flow rate was 12 L / min, and the powder feeding speed was 25 g / min; in this experiment, the calcination method was used to test the oxidation resistance of the ceramic powders prepared in the examples and comparative examples. The mass of the substrate with the coating before calcination was measured using an analytical balance. The substrate with the coating was placed in an electric furnace and calcined in an air environment. After cooling, the mass of the sample after calcination was measured. The calcination temperature was 1000 °C, and the calcination time was 90 h. Calculate the oxidation weight gain per unit area. The greater the weight gain, the worse the oxidation resistance of the powder, and vice versa. The results are shown in Table 1.

[0076] Table 1

[0077] <![CDATA[Mass (mg / cm 2 )]]> Example 1 2.66 Example 2 2.71 Example 3 2.72 Example 4 2.64 Example 5 2.73 Example 6 2.69 Comparative Example 1 6.42 Comparative Example 2 6.35 Comparative Example 3 6.47

[0078] From the comparison of the experimental data of Examples 1-6 and Comparative Examples 1-3 in Table 1, it can be found that the ceramic powder coatings prepared by the present invention have good oxidation resistance.

[0079] By comparison, the weight gains of Examples 1-6 were less than those of Comparative Examples 1-3, indicating that the pulsed atomization technology can accurately control the particle size distribution of the powder particles and generate powder particles with a bimodal distribution. Bimodal distribution means that there are two different particle size ranges of particles in the powder, usually composed of larger particles and smaller particles. This optimization of particle grading can effectively improve the densification and bonding strength of the coating. The larger particles play a skeleton support role in the coating, while the smaller particles fill the gaps between the large particles, thereby improving the density of the coating and thus improving the oxidation resistance of the coating.

[0080] Test Example 2:

[0081] Test of wear resistance:

[0082] Testing method: The ceramic powders prepared in the examples and comparative examples were used to prepare coatings by using the MF-P1000 atmospheric plasma spraying system produced by GTV Company in Germany; the coating substrate was selected as 304 stainless steel material. First, the substrate was degreased and derusted to ensure that the surface of the substrate was pollution-free, and then the substrate was sandblasted with corundum particles; the spraying parameters were as follows: the current was 600 A, the voltage was 70 V, the spraying distance was 110 mm, the helium gas flow rate was 40 L / min, the hydrogen gas flow rate was 12 L / min, and the powder feeding speed was 25 g / min; a high-temperature friction and wear testing machine was used, the load was set to 10 N, the rotation speed was 364 / min, and the testing time was 5 min. The mass loss of the coating after the experiment was measured and used as an index for the wear resistance of the coating; the results are shown in Table 2.

[0083] Table 2

[0084]

[0085]

[0086] From the comparison of the experimental data of Examples 1-6 and Comparative Examples 1-3 in Table 2, it can be found that the ceramic powder coatings prepared by the present invention have good wear resistance.

[0087] By comparison, the mass loss of Examples 1-6 is less than that of Comparative Examples 1-3, indicating that by using the pulsed atomization technology, the particle size distribution of the powder particles can be precisely controlled to generate powder particles with a bimodal distribution. The bimodal distribution means that there are two different particle size ranges of particles in the powder, usually composed of larger particles and smaller particles. This optimization of particle grading can effectively improve the densification and bonding strength of the coating. The larger particles play a role of skeleton support in the coating, while the smaller particles fill the gaps between the large particles, thereby improving the density of the coating and thus improving the wear resistance of the coating.

[0088] Test Example 3:

[0089] Flowability test:

[0090] Testing method: The flowability of the powders obtained in all examples and comparative examples was tested by using a powder flowability tester. The results are shown in Table 3. Taking the flowability of the composite powder obtained in Example 1 as an example, 60 s / 57.4 g means that within 60 s, the mass of the composite powder flowing out of the instrument is 57.4 g.

[0091] Table 3

[0092] Flowability Example 1 60 s / 57.4 g Example 2 60 s / 56.9 g Example 3 60 s / 57.8 g Example 4 60 s / 56.1 g Example 5 60 s / 57.2 g Example 6 60 s / 56.6 g Comparative Example 1 60 s / 48.2 g Comparative Example 2 60 s / 48.1 g Comparative Example 3 60 s / 48.6 g

[0093] From the comparison of the experimental data of Examples 1-6 and Comparative Examples 1-3 in Table 3, it can be found that the ceramic powder prepared by the present invention has good fluidity; it shows that powders with bimodal distribution usually have better fluidity, especially under the condition of optimized particle size distribution; this is because the powder with bimodal distribution is composed of two kinds of particles with different particle sizes, and a "packing effect" can be formed between the larger particles and the smaller particles, thereby improving the overall fluidity and packing density of the powder; in the bimodal distribution, the smaller particles can fill the voids between the larger particles, reducing the friction and resistance between the particles, thereby improving the fluidity of the powder; due to the optimized particle size distribution, the packing density of the powder with bimodal distribution is usually higher than that of the powder with unimodal distribution, which helps the powder to be more uniform and stable during transportation and spraying; in the powder with bimodal distribution, the presence of smaller particles can prevent the direct contact between the larger particles, reduce the agglomeration phenomenon, and further improve the fluidity.

[0094] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be construed as limiting the claimed claim.

Claims

1. A method for preparing black alumina-based ceramic powder for plasma spraying, characterized in that: The preparation method is as follows: (1) Weigh aluminum oxide, titanium oxide, and reducing agent in a mass ratio of 100:(60-90):(0.2-2); (2) forming a melt by an electric melting process under the protection of a protective gas; (3) The melt is atomized into droplets by double pulse atomization and cooled under the protection of a protective gas to obtain a black alumina-based ceramic powder for plasma spraying.

2. The method for preparing black alumina-based ceramic powder for plasma spraying according to claim 1, characterized in that: The protective gas is one of nitrogen, argon, ammonia, and a hydrogen / argon mixed gas.

3. The method for preparing black alumina-based ceramic powder for plasma spraying according to claim 1, characterized in that: The reducing agent in step (1) is one or more of aluminum, titanium or titanium-aluminum alloy; the mass fraction of aluminum oxide in the aluminum oxide is ≥99.0%; the mass fraction of titanium dioxide in the titanium oxide is ≥99.0%.

4. The method for preparing black alumina-based ceramic powder for plasma spraying according to claim 1, characterized in that: The electric melting process in step (2) is: electric melting is carried out in a plasma arc furnace; the melt temperature is 1900-2200°C.

5. The method for preparing black alumina-based ceramic powder for plasma spraying according to claim 1, characterized in that: The atomization method in step (3) is one of centrifugal atomization, jet atomization, and ultrasonic atomization; the double-pulse atomization refers to alternating pulse atomization with two different atomization process parameters.

6. The method for preparing black alumina-based ceramic powder for plasma spraying according to claim 1, characterized in that: The particle size of the black alumina-based ceramic powder for plasma spraying presents a bimodal distribution.

7. The method for preparing black alumina-based ceramic powder for plasma spraying according to claim 1, characterized in that: The black alumina-based ceramic powder for plasma spraying is spherical, and the sphericity is ≥90%.

8. A black alumina-based ceramic powder for plasma spraying prepared according to the method for preparing a black alumina-based ceramic powder for plasma spraying according to any one of claims 1 to 7.

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