A gradient YTO coating material for MoSi2 heating elements and its preparation method

Abstract

The application discloses a gradient YTO coating material for a MoSi2 heating element and a preparation method thereof, relates to the technical field of high-temperature oxidation-resistant coatings, and sequentially prepares the gradient YTO coating composed of YTa3O9, YTaO4 and Y3TaO7 from the inside to the outside on the MoSi2 heating element by adopting a sol-gel method and an electrophoretic deposition method, the coating has good thermal matching with the substrate and high bonding force. The gradient YTO coating prepared on the MoSi2 heating element is high-temperature-resistant and oxidation-resistant, after being examined at 1900 DEG C for 120 minutes by an oxygen-acetylene flame, the coating and the MoSi2 heating element are intact without damage, no glass film appears on the surface, the coating can well protect the substrate, the service temperature of the MoSi2 heating element is improved, and the service life of the MoSi2 heating element is prolonged. The YTO coating prepared by the application has the advantages of simple process flow, simple equipment, low production cost and easy operation.

Description

Technical Field

[0001] This invention relates to the field of high-temperature antioxidant coating technology, specifically to a gradient YTO coating material for MoSi2 heating elements and its preparation method. Background Technology

[0002] With the rapid development of industrial production, the requirements for high-temperature heating elements have increased. Currently, domestically produced MoSi2 heating elements can be used continuously at 1700℃, while imported MoSi2 heating elements can reach a maximum operating temperature of 1850℃. To improve the operating temperature of domestically produced MoSi2 heating elements while extending their service life in high-temperature oxidizing environments, a high-temperature anti-oxidation coating is prepared on the surface of the domestically produced MoSi2 heating elements. Chinese patent CN202310741979.7 utilizes spherical thin-walled hollow nano-stable tetragonal YSZ powder to prepare a YSZ coating using atmospheric plasma spraying technology; however, the coating has many vertical cracks inside and cannot effectively protect the substrate. Chinese patent CN202010887388.7 uses the APS method to prepare a rare earth tantalate coating, but this method has a complex process and expensive equipment. Summary of the Invention

[0003] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a gradient YTO coating material and its preparation method.

[0004] The technical solution of the present invention is as follows:

[0005] A gradient YTO coating material is formed on a substrate by solid-solution of yttrium salt and tantalum salt, forming single-phase compounds with monoclinic crystal structures at each gradient, wherein the phase composition of the single-phase compounds is YTa3O9, YTaO4 or Y3TaO7.

[0006] As a preferred embodiment of the present invention, the following steps are included:

[0007] S1: Weigh the raw materials according to the above phase composition, the raw materials including yttrium salt and tantalum salt;

[0008] S2: Dissolve the raw material from step S1 in a solvent, add a catalyst to obtain a precursor solution, and age it for later use.

[0009] S3: The precursor solution is sequentially coated with a gradient YTO coating with a single phase on the substrate surface using the sol-gel dip-coating method or electrophoretic deposition method to obtain the pre-product;

[0010] S4: The preform obtained in step S3 is sintered under an argon protective atmosphere and calcined at a constant temperature of 1650℃ for 2 to 10 hours to obtain the final product.

[0011] As a preferred embodiment of the present invention, step S1 includes at least the following technical features:

[0012] The yttrium salt includes at least one of yttrium acetate, yttrium isopropanol, yttrium acetylacetone, and yttrium nitrate hexahydrate;

[0013] The tantalum salt includes at least one of tantalum ethoxide, tantalum pentachloride, tantalum n-butoxide, and tantalum isopropoxide;

[0014] The purity of the raw materials is ≥99.99%, and the molar ratio of raw material Y:Ta is 1-3:1-3.

[0015] As a preferred embodiment of the present invention, step S2 includes at least the following technical features:

[0016] Ethanol was used as the solvent; glacial acetic acid was used as the catalyst; the aging temperature was 20-25℃ and the aging time was 24-48h.

[0017] As a preferred embodiment of the present invention, in step S3, the sol-gel impregnation and lifting method is specifically as follows: the substrate is impregnated in the precursor solution for 60-180s, and then the substrate is lifted out at a speed of 0.8-1cm / min, and then dried. The above lifting and drying steps are repeated to obtain a substrate with multiple film layers.

[0018] As a preferred embodiment of the present invention, the electrophoretic deposition method is specifically as follows:

[0019] Using a stainless steel mesh as the anode and the substrate as the cathode, deposition is carried out on the substrate at an electrode spacing of 1–3 cm and a deposition voltage of 80 V–120 V for 1–5 min, using constant voltage electrophoretic deposition; then drying, and repeating the above deposition and drying steps to obtain a substrate with multiple film layers.

[0020] As a preferred embodiment of the present invention, the drying method is specifically as follows: placing the substrate in a vacuum drying oven and drying it at 70-90°C for 5-10 minutes.

[0021] As a preferred embodiment of the present invention, in step S4, the heating rate of sintering is: 3℃ / min for 20℃~150℃, 10℃ / min for 150℃~1200℃, and 3℃ / min for 1200℃~1650℃.

[0022] As a preferred embodiment of the present invention, the substrate is a MoSi2 heating element.

[0023] The beneficial effects of this invention are:

[0024] The present invention provides a gradient YTO coating material, wherein the coating material is formed by solid solution of yttrium salt and tantalum salt to form a single-phase compound with a monoclinic crystal structure, and the phase composition is YTa3O9, YTaO4, or Y3TaO7. The coating has excellent thermophysical properties and excellent thermal stability, and can be used as a high-temperature antioxidant coating material, and has applications in the field of high-temperature antioxidant coatings.

[0025] The present invention provides a method for preparing gradient YTO coating materials, which uses the sol-gel method and electrophoretic deposition method to prepare YTO coatings. This method is not only simple to operate, but also has simpler equipment and lower production cost compared to atmospheric plasma spraying method. The prepared YTO coatings are fully phase-formed, dense, and have good coating performance. Attached Figure Description

[0026] Figure 1 A schematic diagram of the gradient YTO coating designed for Example 2;

[0027] Figure 2 A schematic diagram of the gradient YTO coating designed for Example 3;

[0028] Figure 3 The image shows the microstructure of the gradient YTO coating after testing in Example 2.

[0029] Figure 4 The image shows the microstructure of the gradient YTO coating after testing in Example 3. Detailed Implementation

[0030] This invention provides a high-temperature resistant and oxidation-resistant gradient YTO coating for MoSi2 heating elements and its preparation method, so as to improve the operating temperature of domestically produced MoSi2 heating elements and extend their service life in high-temperature oxidizing environments.

[0031] A gradient YTO coating material is formed by solid-solution of yttrium salt and tantalum salt to form a single-phase compound with a monoclinic crystal structure, wherein the phase composition of the single-phase compound is YTa3O9, YTaO4 or Y3TaO7.

[0032] A method for preparing a gradient YTO coating material, the method comprising the following steps:

[0033] S1: Weigh each raw material according to the phase composition of the coating material using stoichiometry;

[0034] In some embodiments, the raw material is at least one of yttrium salts such as yttrium acetate, yttrium isopropoxide, yttrium acetylacetonate, and yttrium nitrate hexahydrate, and at least one of tantalum salts such as tantalum ethoxide, tantalum pentachloride, tantalum n-butoxide, and tantalum isopropoxide.

[0035] In some embodiments, the purity of the raw materials is ≥99.99% to ensure the uniformity of the phase composition of the synthesized material; the raw materials are weighed according to a Y:Ta molar ratio of 1:3 to 1:3. Preferably, the molar ratio can be 1:3, 1:1, or 3:1.

[0036] S2: Dissolve the raw material from step S1 in a solvent, add a catalyst to obtain a precursor solution, and age it for later use.

[0037] Preferably, anhydrous ethanol is used as the solvent and glacial acetic acid is used as the catalyst.

[0038] It is preferable to dissolve and stir simultaneously, as follows:

[0039] Place the yttrium acetate and tantalum pentachloride weighed in step S1 into a container, add anhydrous ethanol at room temperature and stir to dissolve. After it is fully dissolved, continue to add glacial acetic acid while stirring. After 20-30 minutes, a sol is obtained.

[0040] In some embodiments, the aging temperature is 20-25°C and the aging time is 24-48h. Preferably, the prepared sol is aged at room temperature (20°C) for 24h to ensure that the sol is uniform and stable.

[0041] S3: Prepare a gradient YTO coating on the substrate surface using the sol-gel dip-coating method or electrophoretic deposition method to obtain the pre-product;

[0042] The sol-gel dip-coating method is employed, in which the sol bath is slowly and steadily lowered below the sample. The upper end of the MoSi2 heating element sample is clamped, and the lower end is immersed for 60–180 seconds. The lifting speed is then slowly controlled, with a lifting speed of 0.3–0.8 cm / min. The sample is then pulled out of the sol, and a gel film quickly forms on its surface. The coated sample is then placed in a vacuum drying oven for drying. After ensuring thorough drying according to experimental requirements, a second, third, and subsequent coatings are applied, and the dip-coating process is repeated.

[0043] Alternatively, electrophoretic deposition can be used, with a stainless steel mesh as the anode and a MoSi2 heating element sample as the cathode. Deposition was performed on the substrate sample at an electrode spacing of 1–3 cm and a deposition voltage of 80 V–120 V for 1–5 min under constant voltage electrophoretic deposition; followed by drying. The above deposition and drying steps were repeated to obtain a substrate with multiple film layers.

[0044] The specific drying method is as follows: place the sample in a vacuum drying oven and dry it at 80℃ for 5 to 10 minutes.

[0045] It is preferable to dry the sample at 80°C to fully evaporate the anhydrous ethanol and reduce impurities.

[0046] S4: The preform obtained in step S3 is sintered under an argon protective atmosphere and calcined at a constant temperature of 1650℃ for 2 to 10 hours to obtain the final product. Under these calcination conditions, single-phase YTa3O9, YTaO4, and Y3TaO7 can be synthesized.

[0047] A YTO coating material prepared by the above method has a phase composition including YTa3O9, YTaO4, and Y3TaO7.

[0048] This invention yields a gradient YTO coating composed of YTa3O9, YTaO4, and Y3TaO7 from the inside out. The coating exhibits good thermal compatibility and high adhesion to the substrate. The YTO coating is prepared using the sol-gel method and electrophoretic deposition method, which is not only simple to operate and requires simpler equipment and has lower production costs compared to atmospheric plasma spraying, but also produces a fully formed, dense YTO coating with excellent performance.

[0049] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0050] Example 1

[0051] Step S1: First, the raw materials are yttrium acetate and tantalum ethoxide, weighed according to the molar ratio of Y:Ta of 3:1. The raw materials are placed in a container, and anhydrous ethanol is added to the container while stirring. After 30 minutes, after it is completely dissolved, glacial acetic acid is added to the container while stirring. After 30 minutes, a sol is obtained and aged at room temperature (20°C) for 24 hours for later use.

[0052] Step S2: Polish the surface of the MoSi2 heating element substrate material, and then use the sol-gel method to sequentially lift one part of the sol obtained in step S1 onto the MoSi2 heating element substrate to obtain a YTO high-temperature anti-oxidation coating.

[0053] Step S3: The sol bath is lowered smoothly and slowly below the sample for immersion. The upper end of the MoSi2 heating element sample is clamped, and the lower end is immersed for 120 seconds. Then, the lifting platform is slowly controlled at a speed of 0.4 cm / min to gently pull the sample out of the sol, where a gel film quickly forms. The coated sample is then placed in a vacuum drying oven at 80°C for 3 minutes, followed by air drying in a cool, ventilated place for 3 minutes. Repeat the lifting process to ensure complete drying as required by the experiment.

[0054] Step S4: The sample prepared in step S3 was sintered in a tube furnace under an argon protective atmosphere, heated to 1650℃ and calcined at a constant temperature for 5 hours. The temperature was increased at a rate of 3℃ / min from 20℃ to 150℃, at 10℃ / min from 150℃ to 1200℃, and at 3℃ / min from 1200℃ to 1650℃. A gradient YTO coating material with a thickness of 5μm was obtained.

[0055] Performance test: After the sample was tested at 1900℃ for 30 minutes under an oxy-acetylene flame, some of the coating peeled off, indicating poor adhesion.

[0056] Example 2

[0057] Step S1: Taking the preparation of YTa3O9 as an example. First, the raw materials are yttrium acetate and tantalum ethoxide, weighed according to a Y:Ta molar ratio of 1:3. The raw materials are placed in a container, and anhydrous ethanol is added while stirring. After 30 minutes, once completely dissolved, glacial acetic acid is added while stirring. After another 30 minutes, a sol is obtained and aged at room temperature (20°C) for 24 hours for later use. The preparation of Y3TaO7 (Y:Ta molar ratio of 3:1) is the same as the preparation of YTa3O9.

[0058] Step S2: Polish the surface of the MoSi2 heating element substrate material, and then use the sol-gel method to sequentially lift YTa3O9 and Y3TaO7 onto the MoSi2 heating element substrate to obtain a multi-gradient YTO high-temperature anti-oxidation coating.

[0059] Specifically, the immersion method involves slowly and steadily lowering the sol bath below the sample. The upper end of the MoSi2 heating element sample is clamped, and the lower end is immersed for 120 seconds. Then, the speed of the lifting platform is slowly controlled at 0.4 cm / min to gently pull the sample out of the sol, rapidly forming a gel film on the surface. The coated sample is then placed in a vacuum drying oven at 80℃ for 3 minutes, followed by air drying in a cool, ventilated place for 3 minutes. If necessary, after ensuring thorough drying according to experimental requirements, the first large layer of YTa3O9 is repeatedly pulled out until a certain thickness is achieved, then the second large layer of Y3TaO7 is pulled out.

[0060] Step S3: The sample prepared in step S2 was sintered in a tube furnace under an argon protective atmosphere, heated to 1650℃ and calcined at a constant temperature for 5 hours. The temperature was increased at a rate of 3℃ / min from 20℃ to 150℃, at 10℃ / min from 150℃ to 1200℃, and at 3℃ / min from 1200℃ to 1650℃. A gradient YTO coating material with a thickness of 10μm was obtained.

[0061] Performance testing: The sample was subjected to an oxy-acetylene flame test at 1900℃ for 100 minutes. Figure 2The image shows the microstructure of the gradient YTO coating after evaluation. The coating and the MoSi2 heating element are intact and undamaged, and no glass film appears on the surface.

[0062] Example 3

[0063] Step S1: Taking the preparation of YTa3O9 as an example. First, the raw materials are yttrium acetylacetonate and tantalum pentachloride, weighed according to a Y:Ta molar ratio of 1:3. The raw materials are placed in a container, and anhydrous ethanol is added while stirring. After 30 minutes, once completely dissolved, glacial acetic acid is added while stirring. After another 30 minutes, a sol is obtained and aged at room temperature (20°C) for 24 hours for later use. The preparation of YTaO4 (Y:Ta molar ratio of 1:1) and Y3TaO7 (Y:Ta molar ratio of 3:1) is the same as the preparation of YTa3O9.

[0064] Step 2: Polish the surface of the MoSi2 heating element substrate material, and then use the sol-gel method to lift the three sols obtained in Step 1 onto the MoSi2 heating element substrate in the order of YTa3O9, YTaO4 and Y3TaO7 to obtain a multi-gradient YTO high-temperature anti-oxidation coating.

[0065] Specifically, the immersion method involves slowly and steadily lowering the sol bath below the sample. The upper end of the MoSi2 heating element sample is clamped, and the lower end is immersed for 120 seconds. Then, the lifting platform is slowly controlled at a speed of 0.4 cm / min to gently pull the sample out of the sol, rapidly forming a gel film on the surface. The coated sample is then placed in a vacuum drying oven at 80°C for 3 minutes, followed by air drying in a cool, ventilated place for 3 minutes. If necessary, a second and third layer can be applied after ensuring thorough drying according to experimental requirements, and the process of lifting and lowering is repeated.

[0066] Step 3: The sample prepared in Step 2 was sintered in a tube furnace under an argon protective atmosphere, heated to 1650℃ and calcined for 5 hours. The temperature was increased at a rate of 3℃ / min from 20℃ to 150℃, at 10℃ / min from 150℃ to 1200℃, and at 3℃ / min from 1200℃ to 1650℃. A gradient YTO coating material with a thickness of 20μm was obtained.

[0067] Performance testing: The sample was tested at 1900℃ for 120 minutes under an oxy-acetylene flame. Figure 3 The image shows the microstructure of the gradient YTO coating after evaluation. The coating and the MoSi2 heating element are intact and undamaged, and no glass film appears on the surface.

[0068] Without causing conflict, those skilled in the art can freely combine and use the above-mentioned additional technical features.

[0069] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of the present invention.

Claims

1. A gradient YTO coating material, characterized in that, By solid-solution of yttrium salt and tantalum salt, a single-phase compound with a monoclinic crystal structure is formed on the matrix at each gradient, wherein the phase composition of the single-phase compound is: YTa3O9, YTaO4 or Y3TaO7; The substrate uses MoSi2 heating elements; The preparation method of the coating material includes the following steps: S1: Weigh the raw materials according to the aforementioned phase composition, wherein the raw materials include yttrium salt and tantalum salt; S2: Dissolve the raw material from step S1 in a solvent, add a catalyst to obtain a precursor solution, and age it for later use. S3: The precursor solution is sequentially coated with a gradient YTO coating with a single phase on the substrate surface using the sol-gel dip-coating method or electrophoretic deposition method to obtain the pre-product; S4: The preform obtained in step S3 is sintered under an argon protective atmosphere and calcined at a constant temperature of 1650℃ for 2 to 10 hours to obtain the final product.

2. A method for preparing a gradient YTO coating material as described in claim 1, characterized in that, Includes the following steps: S1: Weigh the raw materials according to the aforementioned phase composition, wherein the raw materials include yttrium salt and tantalum salt; S2: Dissolve the raw material from step S1 in a solvent, add a catalyst to obtain a precursor solution, and age it for later use. S3: The precursor solution is sequentially coated with a gradient YTO coating with a single phase on the substrate surface using the sol-gel dip-coating method or electrophoretic deposition method to obtain the pre-product; S4: The preform obtained in step S3 is sintered under an argon protective atmosphere and calcined at a constant temperature of 1650℃ for 2 to 10 hours to obtain the final product.

3. The method for preparing a gradient YTO coating material according to claim 2, characterized in that, Step S1 includes at least the following technical features: The yttrium salt includes at least one of yttrium acetate, yttrium isopropanol, yttrium acetylacetone, and yttrium nitrate hexahydrate; The tantalum salt includes at least one of tantalum ethoxide, tantalum pentachloride, tantalum n-butoxide, and tantalum isopropoxide; The purity of the raw materials is ≥99.99%, and the molar ratio of raw material Y:Ta is 1-3:1-3.

4. The method for preparing a gradient YTO coating material according to claim 2, characterized in that, Step S2 includes at least the following technical features: Ethanol was used as the solvent; glacial acetic acid was used as the catalyst; the aging temperature was 20-25℃ and the aging time was 24-48h.

5. The method for preparing a gradient YTO coating material according to claim 2, characterized in that, In step S3, the sol-gel impregnation and lifting method is as follows: the substrate is impregnated in the precursor solution for 60-180 seconds, and then the substrate is lifted out at a speed of 0.8-1 cm / min. After drying, the lifting and drying steps are repeated to obtain a substrate with multiple film layers.

6. The method for preparing a gradient YTO coating material according to claim 2, characterized in that, The electrophoretic deposition method is as follows: Using a stainless steel mesh as the anode and the substrate as the cathode, deposition is carried out on the substrate at an electrode spacing of 1–3 cm and a deposition voltage of 80 V–120 V for 1–5 min, using constant voltage electrophoretic deposition; then drying, and repeating the above deposition and drying steps to obtain a substrate with multiple film layers.

7. A method for preparing a gradient YTO coating material according to claim 5 or 6, characterized in that, The drying method specifically involves placing the substrate in a vacuum drying oven and drying it at 70-90℃ for 5-10 minutes.

8. A method for preparing a gradient YTO coating material according to claim 2, characterized in that, In step S4, the heating rate for sintering is as follows: 3℃ / min for 20℃~150℃, 10℃ / min for 150℃~1200℃, and 3℃ / min for 1200℃~1650℃.

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