A molybdenum alloy surface anti-cracking coating and a preparation method thereof

Abstract

The application belongs to the technical field of metal coating preparation, and particularly relates to a molybdenum alloy surface anti-cracking coating and a preparation method thereof. On the basis of a silicide coating, two alloy elements Zr and B are added. Under high temperature, the B element and the Zr element react with oxygen, and the products can effectively prevent further cracking of the coating. The coating is prepared by adopting a slurry sintering method, and the coating can protect the substrate of any size. Meanwhile, the equipment cost is low, the process is simple, and industrialization is easy to realize.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal coating preparation, and particularly relates to a molybdenum alloy surface anti-cracking coating and a preparation method thereof. BACKGROUND

[0002] The molybdenum alloy has excellent characteristics of high melting point, high creep resistance, high thermal conductivity and low thermal expansion coefficient, but has defects of low-temperature brittleness, low room-temperature recrystallization temperature and poor high-temperature oxidation resistance, which result in that the molybdenum alloy cannot serve for a long time. Commonly used methods are alloying and coating preparation, but alloying is difficult to realize due to the limitation of the substrate, so coating is more commonly used. However, the existing coating and the substrate are prone to cracking due to the large difference in the thermal expansion coefficient, and therefore, it is urgent to develop a molybdenum alloy surface anti-cracking coating which can effectively prevent cracking. SUMMARY

[0003] To solve the problems in the prior art, the main purpose of the present application is to provide a molybdenum alloy surface anti-cracking coating and a preparation method thereof.

[0004] To solve the above technical problems, according to one aspect of the present application, the present application provides the following technical scheme:

[0005] A preparation method of a molybdenum alloy surface anti-cracking coating, comprising the following steps:

[0006] S1, polishing the surface of a molybdenum alloy substrate with sandpaper, cleaning the impurities on the surface with anhydrous ethanol, and then drying to obtain a treated molybdenum alloy substrate;

[0007] S2, mixing Si, ZrB2, B, SiC, MnO2 and sintering aid powders in a certain proportion to obtain a mixed powder, wet ball milling and mixing to prepare a uniform slurry;

[0008] S3, using a spraying coating process to coat a slurry coating with uniform thickness on the treated molybdenum alloy substrate, and after natural drying, drying treatment is performed to obtain a dry body;

[0009] S4, placing the dry body into a pre-fired crucible and sintering in a vacuum sintering furnace to obtain an anti-cracking coating on the surface of the molybdenum alloy.

[0010] As a preferred scheme of the preparation method of the molybdenum alloy surface anti-cracking coating, in the step S2, the mixed powder comprises, in mass percentage, Si: 20-60%, ZrB2: 5-30%, B: 5-30%, SiC: 5%, MnO2: 30%, and the balance is a sintering aid.

[0011] As a preferred scheme of the preparation method of the molybdenum alloy surface anti-cracking coating, in the step S2, the sintering aid is PVB.

[0012] As a preferred scheme of the preparation method of the molybdenum alloy surface anti-cracking coating, in the step S2, the anhydrous ethanol is added for wet ball milling, the ball milling speed is 300 rpm, and the ball milling time is 6 h.

[0013] As a preferred scheme of the preparation method of the molybdenum alloy surface anti-cracking coating, in the step S3, the air pressure of the spray gun is 0.8 MPa, the spraying distance is 100 mm, and the drying time is 2.0 h.

[0014] As a preferred scheme of the preparation method of the molybdenum alloy surface anti-cracking coating, in the step S3, the thickness of the slurry coating is 120-200 μm.

[0015] As a preferred scheme of the preparation method of the molybdenum alloy surface anti-cracking coating, in the step S4, the sintering temperature is 800 ℃, the sintering time is 1 h, and the sintering is performed in an argon atmosphere.

[0016] To solve the above technical problems, according to another aspect of the present application, the present application provides the following technical scheme.

[0017] A molybdenum alloy surface anti-cracking coating is prepared by the above preparation method.

[0018] As a preferred scheme of the molybdenum alloy surface anti-cracking coating, the thickness of the anti-cracking coating is 100-180 μm, the high-temperature oxidation is performed at 1000-1200 ℃ for 1 h, and the mass change of the coating before and after the oxidation is ≤4.0 g.

[0019] The present application has the following beneficial effects.

[0020] The present application provides a molybdenum alloy surface anti-cracking coating and a preparation method thereof. On the basis of the silicide coating, Zr and B are added as alloy elements. At high temperature, B and Zr react with oxygen, and the products can effectively prevent further cracking of the coating. The coating is prepared by slurry sintering, which can protect the substrate of any size, and the equipment cost is low, the process is simple, and industrialization is easy to realize. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only need to be some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of the drawings shown.

[0022] Figure 1 SEM image of the coating surface of Example 1 of the present application;

[0023] Figure 2 SEM image of the coating cross section of Example 1 of the present application;

[0024] Figure 3 SEM image of the coating surface of Comparative Example 1 of the present application;

[0025] Figure 4 SEM image of the coating cross section of Comparative Example 1 of the present application.

[0026] Figure 5 SEM image of the coating surface of Comparative Example 2 of the present application;

[0027] Figure 6 SEM image of the coating cross section of Comparative Example 2 of the present application.

[0028] Figure 7 SEM image of the coating surface of Comparative Example 3 of the present application;

[0029] Figure 8 SEM image of the coating cross section of Comparative Example 3 of the present application.

[0030] Figure 9 Mass change graph of the sample of each embodiment of the present application at different oxidation temperatures.

[0031] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort belong to the protection scope of the present application.

[0033] The present application provides a crack-resistant coating on the surface of molybdenum alloy and a preparation method thereof. On the basis of the silicide coating, two alloying elements, Zr and B, are added. At high temperature, the B element and the Zr element react with oxygen, and the products can effectively prevent further cracking of the coating.

[0034] The technical scheme of the present application will be further described in combination with specific examples.

[0035] Example 1

[0036] A preparation method of a molybdenum alloy surface anti-cracking coating comprises the following steps:

[0037] S1, polishing the surface of a molybdenum alloy substrate with 400-2000# sandpaper, cleaning the impurities on the surface with anhydrous ethanol, and then drying to obtain a treated molybdenum alloy substrate;

[0038] S2, mixing Si, ZrB2, B, SiC, MnO2, and sintering additives in a certain proportion to obtain a mixed powder, wet ball milling, and making a uniform slurry; the mixed powder, by mass percentage, comprises: Si: 53%, ZrB2: 5%, B: 5%, SiC: 5%, MnO2: 30%, and the balance is a sintering additive; the sintering additive is PVB, anhydrous ethanol is added, and a QM-1SP planetary high-energy ball mill is used for ball milling, the ball milling speed is 300 rpm, and the ball milling time is 6h;

[0039] S3, using a spraying coating process to coat a uniform thickness of slurry coating on the treated molybdenum alloy substrate, and after natural drying, placing it in a vacuum drying oven for drying treatment to obtain a dry body; the air pressure of the spray gun is 0.8 MPa, the spraying distance is 100 mm, the drying time is 2.0h, and the thickness of the slurry coating is 135μm;

[0040] S4, placing the dry body into a pre-fired crucible and sintering in a vacuum sintering furnace, the sintering temperature is 800℃, the sintering time is 1h, and the sintering is carried out in an argon atmosphere, to obtain an anti-cracking coating on the surface of the molybdenum alloy, the thickness of which is 134.02μm, and the SEM image of the surface is shown in Figure 1 , it can be seen that the coating surface has high density; the SEM image of the cross section is shown in Figure 2 , and no obvious micro-cracks are observed.

[0041] Example 2

[0042] A preparation method of a molybdenum alloy surface anti-cracking coating comprises the following steps:

[0043] S1, polishing the surface of a molybdenum alloy substrate with 400-2000# sandpaper, cleaning the impurities on the surface with anhydrous ethanol, and then drying to obtain a treated molybdenum alloy substrate;

[0044] S2, Si, ZrB2, B, SiC, MnO2, sintering aid powder is mixed according to a certain proportion to obtain mixed powder, wet ball milling is carried out, and uniform slurry is prepared; the mixed powder comprises, in percentage by mass: Si: 48%, ZrB2: 10%, B: 5%, SiC: 5%, MnO2: 30%, and the balance is a sintering aid; the sintering aid is PVB, anhydrous ethanol is added, and QM-1SP type planetary high-energy ball mill is used for ball milling mixing, the ball milling speed is 300 rpm, and the ball milling time is 6 h;

[0045] S3, a spraying coating process is used to coat a slurry coating with uniform thickness on the treated molybdenum alloy substrate, the slurry coating is naturally dried, then placed in a vacuum drying box for drying treatment to obtain a dried green body; the air pressure of the spray gun is 0.8 MPa, the spraying distance is 100 mm, the drying time is 2.0 h, and the thickness of the slurry coating is 126.78 μm;

[0046] S4, the dried green body is placed in a pre-fired crucible and sintered in a vacuum sintering furnace, the sintering temperature is 800 DEG C, the sintering time is 1 h, argon atmosphere is used for sintering, and a crack-resistant coating with a thickness of 104.41 μm is obtained on the surface of the molybdenum alloy.

[0047] Example 3

[0048] A preparation method of a crack-resistant coating on a molybdenum alloy surface, comprising the following steps:

[0049] S1, the surface of the molybdenum alloy substrate is polished by using 400-2000# sandpaper, the impurities on the surface are cleaned with anhydrous ethanol, and then the treated molybdenum alloy substrate is obtained after drying;

[0050] S2, Si, ZrB2, B, SiC, MnO2, sintering aid powder is mixed according to a certain proportion to obtain mixed powder, wet ball milling is carried out, and uniform slurry is prepared; the mixed powder comprises, in percentage by mass: Si: 48%, ZrB2: 5%, B: 10%, SiC: 5%, MnO2: 30%, and the balance is a sintering aid; the sintering aid is PVB, anhydrous ethanol is added, and QM-1SP type planetary high-energy ball mill is used for ball milling mixing, the ball milling speed is 300 rpm, and the ball milling time is 6 h;

[0051] S3, a spraying coating process is used to coat a slurry coating with uniform thickness on the treated molybdenum alloy substrate, the slurry coating is naturally dried, then placed in a vacuum drying box for drying treatment to obtain a dried green body; the air pressure of the spray gun is 0.8 MPa, the spraying distance is 100 mm, the drying time is 2.0 h, and the thickness of the slurry coating is 126.78 μm;

[0052] S4, put the dried body into a pre-burned crucible and sinter in a vacuum sintering furnace, the sintering temperature is 800 DEG C, the sintering time is 1h, the sintering adopts argon atmosphere, and the anti-cracking coating with a thickness of 167.41 μm is obtained on the surface of the molybdenum alloy.

[0053] Example 4

[0054] A preparation method of an anti-cracking coating on a molybdenum alloy surface, comprising the following steps:

[0055] S1, the surface of the molybdenum alloy substrate is polished by using 400-2000# sandpaper, the impurities on the surface are cleaned by using anhydrous ethanol, and then the treated molybdenum alloy substrate is obtained by drying;

[0056] S2, the Si, ZrB2, B, SiC, MnO2 and sintering aid powder are mixed according to a certain proportion to obtain a mixed powder, wet ball milling is carried out, and a uniform slurry is prepared; the mixed powder comprises, in mass percentage: Si: 43%, ZrB2: 10%, B: 10%, SiC: 5%, MnO2: 30%, and the balance is a sintering aid; the sintering aid is PVB, anhydrous ethanol is added, and ball milling is carried out by using a QM-1SP planetary high-energy ball mill, the ball milling speed is 300 rpm, and the ball milling time is 6h;

[0057] S3, a slurry coating with uniform thickness is coated on the treated molybdenum alloy substrate by using a spraying coating process, and after natural drying, the dried body is obtained by drying treatment in a vacuum drying box; the air pressure of the spray gun is 0.8 MPa during spraying, the spraying distance is 100 mm, the drying time is 2.0h, and the thickness of the slurry coating is 188.37 μm;

[0058] S4, put the dried body into a pre-burned crucible and sinter in a vacuum sintering furnace, the sintering temperature is 800 DEG C, the sintering time is 1h, the sintering adopts argon atmosphere, and the anti-cracking coating with a thickness of 167.41 μm is obtained on the surface of the molybdenum alloy.

[0059] Example 5

[0060] A preparation method of an anti-cracking coating on a molybdenum alloy surface, comprising the following steps:

[0061] S1, the surface of the molybdenum alloy substrate is polished by using 400-2000# sandpaper, the impurities on the surface are cleaned by using anhydrous ethanol, and then the treated molybdenum alloy substrate is obtained by drying;

[0062] S2, the Si, ZrB2, B, SiC, MnO2, sintering aid powder is mixed according to a certain proportion to obtain a mixed powder, wet ball milling is carried out, and a uniform slurry is prepared; the mixed powder comprises, in percentage by mass: Si: 33%, ZrB2: 10%, B: 20%, SiC: 5%, MnO2: 30%, and the balance is a sintering aid; the sintering aid is PVB, anhydrous ethanol is added, and QM-1SP type planetary high-energy ball mill is used for ball milling mixing, the ball milling speed is 300 rpm, and the ball milling time is 6 h;

[0063] S3, a slurry coating with uniform thickness is coated on the treated molybdenum alloy substrate by using a spraying coating process, and after natural drying, the dried body is obtained by drying treatment in a vacuum drying box; the air pressure of the spray gun is 0.8 MPa, the spraying distance is 100 mm, the drying time is 2.0 h, and the thickness of the slurry coating is 168.86 μm;

[0064] S4, the dried body is placed in a pre-fired crucible and sintered in a vacuum sintering furnace, the sintering temperature is 800 ℃, the sintering time is 1 h, argon atmosphere is used for sintering, and the anti-cracking coating with a thickness of 166.05 μm is obtained on the surface of the molybdenum alloy, and no severe oxidation occurs at a temperature of ≤1200 ℃.

[0065] Comparative Example 1

[0066] The difference from Example 1 is that in step S2, the mixed powder comprises, in percentage by mass: Si: 45%, B: 18%, SiC: 5%, MnO2: 30%, and the balance is a sintering aid.

[0067] The SEM image of the coating surface of the present comparative example is shown in Figure 3 , and it can be seen that the coating surface has obvious surface cracking; the SEM image of the cross section is shown in Figure 4 , and the coating has coating cracking phenomenon.

[0068] Comparative Example 2

[0069] The difference from Example 1 is that in step S2, the mixed powder comprises, in percentage by mass: Si: 62%, ZrB2: 3%, SiC: 5%, MnO2: 25%, and the balance is a sintering aid.

[0070] The SEM image of the coating surface of the present comparative example is shown in Figure 5 , and it can be seen that the coating surface has obvious surface cracking; the SEM image of the cross section is shown in Figure 6 , and the coating has coating cracking phenomenon.

[0071] Comparative Example 3

[0072] The mixed powder in step S2 comprises, in percentage by mass: Si: 63%, SiC: 5%, MnO2: 30%, and the rest is sintering aid.

[0073] The SEM image of the coating surface of the present comparative example is shown in Figure 7 The SEM image of the coating surface of the present comparative example is shown in Figure 8 The SEM image of the coating surface of the present comparative example is shown in

[0074] The molybdenum alloy with the anti-cracking coating prepared in examples 1-5 was high-temperature oxidized at 1000℃, 1100℃, 1200℃ for 1h respectively, and the mass change of the coating before and after oxidation is shown in Figure 9 As shown in the table, at a temperature below 1200℃, the anti-cracking coating on the surface of the molybdenum alloy of examples 1-5 did not occur severe oxidation.

[0075] From the above examples and comparative examples, it can be seen that, on the basis of the silicide coating, the present application adds two alloying elements Zr and B. At high temperature, the B element and the Zr element react with oxygen, and the product can effectively prevent further cracking of the coating. The present application uses the slurry sintering method to prepare the coating, which can protect the substrate of any size, and has low equipment cost, simple process and easy industrialization.

[0076] The above description is only the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields based on the inventive concept of the present application is included in the patent protection scope of the present application.

Claims

1. A method for preparing a crack-resistant coating on a molybdenum alloy surface, characterized in that, Includes the following steps: S1. After polishing the surface of the molybdenum alloy substrate with sandpaper, clean the impurities on the surface with anhydrous ethanol, and then dry it to obtain the treated molybdenum alloy substrate. S2. Mix Si, ZrB2, B, SiC, MnO2, and sintering aid powders in a certain proportion to obtain a mixed powder, and perform wet ball milling to prepare a uniform slurry; the mixed powder, by mass percentage, includes: Si: 20~43%, ZrB2: 5~10%, B: 5~10%, SiC: 5%, MnO2: 30%, with the balance being sintering aids; S3. A uniform slurry coating with a thickness of 120~200μm is applied to the treated molybdenum alloy substrate using a spray coating process. After natural drying, the substrate is dried to obtain a dried blank. S4. Place the dried blank into a pre-fired crucible and sinter it in a vacuum sintering furnace to obtain a crack-resistant coating on the surface of the molybdenum alloy. The thickness of the anti-cracking coating is 100~180μm. After high-temperature oxidation at 1000~1200℃ for 1h, the mass change of the coating before and after oxidation is ≤4.0g.

2. The method for preparing the anti-cracking coating on the surface of molybdenum alloy according to claim 1, characterized in that, In step S2, the sintering aid is PVB.

3. The method for preparing the anti-cracking coating on the surface of molybdenum alloy according to claim 1, characterized in that, In step S2, anhydrous ethanol is added for wet ball milling at a speed of 300 rpm for 6 hours.

4. The method for preparing the anti-cracking coating on the surface of molybdenum alloy according to claim 1, characterized in that, In step S3, the air pressure of the spray gun is 0.8 MPa, the spraying distance is 100 mm, and the drying time is 2.0 h.

5. The method for preparing the anti-cracking coating on the surface of molybdenum alloy according to claim 1, characterized in that, In step S4, the sintering temperature is 800℃, the sintering time is 1 hour, and the sintering is carried out in an argon atmosphere.

6. A crack-resistant coating for molybdenum alloy surfaces, characterized in that, The anti-cracking coating on the surface of molybdenum alloy was prepared using the method described in any one of claims 1-5.

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