A double-layer oxidation-resistant coating for a niobium alloy surface and a method for preparing the same

Abstract

The present application belongs to the technical field of metal coating preparation, and particularly relates to a double-layer oxidation-resistant coating on the surface of a niobium alloy and a preparation method thereof. A Si-Cr-Ti-Al inner coating and a MoSi2-Al-SiC outer coating are sequentially prepared on the surface of the niobium alloy. The SiC in the outer coating serves as a reinforcing body, and the Al and MoSi2 form a relatively continuous Al2O3 and SiO2 protective film. The inner coating serves as an intermediate layer, and the Cr, Si, Ti and Al in the inner coating contact with the permeated oxygen to generate Cr2O3, SiO2, TiO2 and Al2O3, which can greatly reduce the oxygen permeation rate and improve the oxidation resistance of the coating. The composite coating significantly improves the resistance of the niobium alloy to high-temperature oxidation.

Description

Technical Field

[0001] This invention belongs to the field of metal coating preparation technology, specifically a double-layer anti-oxidation coating on the surface of a niobium alloy and its preparation method. Background Technology

[0002] Niobium alloys possess high melting points, high hardness, and relatively good mechanical and corrosion resistance, making them widely used in nuclear and aerospace industries. However, due to their low initial oxidation temperature, severe oxidation occurs at 600℃, resulting in poor oxidation resistance. Therefore, oxide, aluminide, or silicide coatings are typically applied to the surface of niobium alloys to improve their oxidation resistance and meet the needs of modern aerospace technology. Current research indicates that Si-Cr-Ti coatings applied to niobium alloy surfaces achieve good stability in static air at 1400℃, but this single coating is insufficient for long-term use in environments with service temperatures reaching 1500℃ or higher. Summary of the Invention

[0003] To address the problems existing in the prior art, the main objective of this invention is to propose a double-layer anti-oxidation coating for the surface of niobium alloys and its preparation method.

[0004] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0005] A method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy includes the following steps:

[0006] S1. Use sandpaper to rough grind the surface of the niobium alloy, then rinse with water, and then use alkaline solution, pickling solution and anhydrous ethanol in sequence for ultrasonic cleaning. Finally, blow dry and set aside for use.

[0007] S2. The Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder are initially ground using a planetary ball mill, and then dried for later use.

[0008] S3. Mix the Si powder, Cr powder, Ti powder and Al powder processed in step S2 in a certain proportion. Mix the MoSi2 powder, Al powder and SiC powder processed in step S2 in a certain proportion. Add appropriate amounts of diluent and binder respectively and then mix them with a high-energy planetary ball mill to prepare a uniform slurry for later use.

[0009] S4. A Si-Cr-Ti-Al slurry coating is prepared on the niobium alloy surface treated in step S1 by spraying. After natural drying and vacuum furnace drying, it is sent to a vacuum sintering furnace for sintering to obtain a Si-Cr-Ti-Al inner coating for later use.

[0010] S5. The sample processed in step S4 is coated with MoSi2-Al-SiC slurry by spraying. The sample is then dried naturally and in a vacuum furnace, and then sintered in a vacuum sintering furnace to obtain the MoSi2-Al-SiC outer coating.

[0011] In a preferred embodiment of the method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to the present invention, in step S2, the particle size of the Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder and SiC powder after preliminary grinding is 10-40 μm.

[0012] In a preferred embodiment of the method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to the present invention, in step S3, the ball-to-material ratio of the ball mill is 20:1, the rotation speed is 300 r / min, and the mixing time of the ball mill is 24 h, of which 12 h is for forward and 12 h is for reverse rotation.

[0013] In a preferred embodiment of the method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to the present invention, in step S3, the mass ratio of Si powder, Cr powder, Ti powder and Al powder is (30-50):(10-30):15:15.

[0014] In a preferred embodiment of the method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to the present invention, in step S3, the mass ratio of MoSi2 powder, Al powder, and SiC powder is (70-80):(5-30):5.

[0015] In a preferred embodiment of the method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to the present invention, in step S3, the binder is polyvinyl butyral and the diluent is anhydrous ethanol.

[0016] In a preferred embodiment of the method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to the present invention, the natural drying time in steps S4 and S5 is 2 days.

[0017] In a preferred embodiment of the method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to the present invention, in steps S4 and S5, the vacuum furnace drying adopts a stepped heating method, holding at 40°C for 0.5h, then heating to 65°C and holding for 0.5h, and finally holding at 100°C for 1.0h.

[0018] In a preferred embodiment of the method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to the present invention, in steps S4 and S5, the temperature is increased from 400°C to a sintering holding temperature of 1570°C at a heating rate of 10°C / min, and held for 0.5 hours.

[0019] To solve the above-mentioned technical problems, according to another aspect of the present invention, the present invention provides the following technical solution:

[0020] A double-layer anti-oxidation coating on the surface of a niobium alloy is prepared using the above-described method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy.

[0021] As a preferred embodiment of the double-layer anti-oxidation coating on the surface of a niobium alloy according to the present invention, the double-layer anti-oxidation coating on the surface of the niobium alloy includes a Si-Cr-Ti-Al inner coating and a MoSi2-Al-SiC outer coating. The thickness of the Si-Cr-Ti-Al inner coating is 10-100 μm, the thickness of the MoSi2-Al-SiC outer coating is 15-110 μm, and the static anti-oxidation life of the double-layer anti-oxidation coating on the surface of the niobium alloy is more than 15 hours in air at 1700℃.

[0022] The beneficial effects of this invention are as follows:

[0023] This invention proposes a double-layer anti-oxidation coating for niobium alloy surfaces and its preparation method. A Si-Cr-Ti-Al inner coating and a MoSi2-Al-SiC outer coating are sequentially prepared on the niobium alloy surface. In the outer coating, SiC acts as a reinforcement, while Al and MoSi2 form a relatively continuous protective film of Al2O3 and SiO2. The inner coating serves as an intermediate layer, where Cr, Si, Ti, and Al come into contact with infiltrated oxygen, generating Cr2O3, SiO2, TiO2, and Al2O3. This significantly reduces oxygen permeability and improves the coating's anti-oxidation ability. This composite coating significantly enhances the niobium alloy's resistance to high-temperature oxidation. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0025] Figure 1 The images shown are SEM images of the surface and cross-section of Embodiment 1 of the present invention.

[0026] Figure 2 The images shown are SEM images of the surface and cross-section of Comparative Example 1 of this invention.

[0027] Figure 3 The images shown are SEM images of the surface and cross-section of Comparative Example 2 of this invention.

[0028] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0029] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention proposes a double-layer anti-oxidation coating for the surface of niobium alloy and its preparation method. A Si-Cr-Ti-Al inner coating and a MoSi2-Al-SiC outer coating are sequentially prepared on the surface of niobium alloy, exhibiting excellent anti-oxidation performance. The double-layer anti-oxidation coating on the surface of niobium alloy has a static anti-oxidation life of more than 15 hours in air at 1700℃.

[0031] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0032] Example 1

[0033] A method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy includes the following steps:

[0034] S1. Use 200-2000# sandpaper to rough grind the niobium alloy surface, then rinse with clean water, and then use alkaline solution, pickling solution and anhydrous ethanol for ultrasonic cleaning in sequence. Finally, blow dry and set aside for use.

[0035] S2. The Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder are pre-ground using a planetary ball mill. The particle size of the Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder after pre-grinding is 10-40 μm. They are then dried for later use.

[0036] S3. Mix the Si powder, Cr powder, Ti powder, and Al powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of Si powder is 35wt%, the content of Cr powder is 25wt%, the content of Ti powder is 15wt%, and the content of Al powder is 15wt%; add 8wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix the MoSi2 powder, Al powder, and SiC powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of MoSi2 powder is 70wt%, the content of Al powder is 18wt%, and the content of SiC powder is 5wt%; add 5wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix them separately using a high-energy planetary ball mill, with a ball-to-material ratio of 20:1, a rotation speed of 300 r / min, and a mixing time of 24 h, including 12 h in each direction; prepare a uniform slurry for later use.

[0037] S4. A Si-Cr-Ti-Al slurry coating was prepared on the niobium alloy surface treated in step S1 using a spraying method. After natural drying and vacuum furnace drying, the natural drying time was 2 days. The vacuum furnace drying adopted a stepped heating method, holding at 40℃ for 0.5h, then raising the temperature to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it was sent to a vacuum sintering furnace for sintering. During sintering, the temperature was raised from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain a Si-Cr-Ti-Al inner coating with a thickness of 80μm, which was then set aside for later use.

[0038] S5. The sample processed in step S4 is coated with MoSi2-Al-SiC slurry using a spraying method. It is then subjected to natural drying and vacuum furnace drying. The natural drying time is 2 days. The vacuum furnace drying adopts a stepped heating method, holding at 40℃ for 0.5h, then heating to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it is sent to a vacuum sintering furnace for sintering. During sintering, the temperature is increased from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain the MoSi2-Al-SiC outer coating with a thickness of 100μm.

[0039] The surface and cross-sectional SEM images of the double-layer anti-oxidation coating on the niobium alloy surface prepared in this embodiment are shown below. Figure 1 As shown (the left side is the surface SEM image, and the right side is the cross-sectional SEM image), the coating surface is relatively smooth and no obvious cracks were found; the inner coating and outer coating have a good bonding effect, and the coating is dense and uniform inside.

[0040] Example 2

[0041] A method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy includes the following steps:

[0042] S1. Use 200-2000# sandpaper to rough grind the niobium alloy surface, then rinse with clean water, and then use alkaline solution, pickling solution and anhydrous ethanol for ultrasonic cleaning in sequence. Finally, blow dry and set aside for use.

[0043] S2. The Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder are pre-ground using a planetary ball mill. The particle size of the Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder after pre-grinding is 10-40 μm. They are then dried for later use.

[0044] S3. Mix the Si powder, Cr powder, Ti powder, and Al powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of Si powder is 35wt%, the content of Cr powder is 28wt%, the content of Ti powder is 15wt%, and the content of Al powder is 15wt%; add 5wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix the MoSi2 powder, Al powder, and SiC powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of MoSi2 powder is 70wt%, the content of Al powder is 20wt%, and the content of SiC powder is 5wt%; add 3wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix them separately using a high-energy planetary ball mill, with a ball-to-material ratio of 20:1, a rotation speed of 300 r / min, and a mixing time of 24 h, including 12 h in each direction; prepare a uniform slurry for later use.

[0045] S4. A Si-Cr-Ti-Al slurry coating was prepared on the niobium alloy surface treated in step S1 using a spraying method. After natural drying and vacuum furnace drying, the natural drying time was 2 days. The vacuum furnace drying adopted a stepped heating method, holding at 40℃ for 0.5h, then raising the temperature to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it was sent to a vacuum sintering furnace for sintering. During sintering, the temperature was raised from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain a Si-Cr-Ti-Al inner coating with a thickness of 30μm, which was then set aside for later use.

[0046] S5. The sample processed in step S4 is coated with MoSi2-Al-SiC slurry using a spraying method. It is then subjected to natural drying and vacuum furnace drying. The natural drying time is 2 days. The vacuum furnace drying adopts a stepped heating method, holding at 40℃ for 0.5h, then heating to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it is sent to a vacuum sintering furnace for sintering. During sintering, the temperature is increased from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain the MoSi2-Al-SiC outer coating with a thickness of 50μm.

[0047] Example 3

[0048] A method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy includes the following steps:

[0049] S1. Use 200-2000# sandpaper to rough grind the niobium alloy surface, then rinse with clean water, and then use alkaline solution, pickling solution and anhydrous ethanol for ultrasonic cleaning in sequence. Finally, blow dry and set aside for use.

[0050] S2. The Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder are pre-ground using a planetary ball mill. The particle size of the Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder after pre-grinding is 10-40 μm. They are then dried for later use.

[0051] S3. Mix the Si powder, Cr powder, Ti powder, and Al powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of Si powder is 35wt%, the content of Cr powder is 30wt%, the content of Ti powder is 15wt%, and the content of Al powder is 15wt%; add 3wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix the MoSi2 powder, Al powder, and SiC powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of MoSi2 powder is 70wt%, the content of Al powder is 20wt%, and the content of SiC powder is 5wt%; add 1wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix them separately using a high-energy planetary ball mill, with a ball-to-material ratio of 20:1, a rotation speed of 300 r / min, and a mixing time of 24 h, including 12 h in each direction; prepare a uniform slurry for later use.

[0052] S4. A Si-Cr-Ti-Al slurry coating was prepared on the niobium alloy surface treated in step S1 using a spraying method. After natural drying and vacuum furnace drying, the natural drying time was 2 days. The vacuum furnace drying adopted a stepped heating method, holding at 40℃ for 0.5h, then raising the temperature to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it was sent to a vacuum sintering furnace for sintering. During sintering, the temperature was raised from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain a Si-Cr-Ti-Al inner coating with a thickness of 10μm, which was then set aside for later use.

[0053] S5. The sample processed in step S4 is coated with MoSi2-Al-SiC slurry using a spraying method. It is then subjected to natural drying and vacuum furnace drying. The natural drying time is 2 days. The vacuum furnace drying adopts a stepped heating method, holding at 40℃ for 0.5h, then heating to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it is sent to a vacuum sintering furnace for sintering. During sintering, the temperature is increased from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain the MoSi2-Al-SiC outer coating with a thickness of 20μm.

[0054] Example 4

[0055] A method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy includes the following steps:

[0056] S1. Use 200-2000# sandpaper to rough grind the niobium alloy surface, then rinse with clean water, and then use alkaline solution, pickling solution and anhydrous ethanol for ultrasonic cleaning in sequence. Finally, blow dry and set aside for use.

[0057] S2. The Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder are pre-ground using a planetary ball mill. The particle size of the Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder after pre-grinding is 10-40 μm. They are then dried for later use.

[0058] S3. Mix the Si powder, Cr powder, Ti powder, and Al powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of Si powder is 35wt%, the content of Cr powder is 33wt%, the content of Ti powder is 15wt%, and the content of Al powder is 15wt%; add 1wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix the MoSi2 powder, Al powder, and SiC powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of MoSi2 powder is 75wt%, the content of Al powder is 15wt%, and the content of SiC powder is 5wt%; add 3wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix them separately using a high-energy planetary ball mill, with a ball-to-material ratio of 20:1, a rotation speed of 300 r / min, and a mixing time of 24 h, including 12 h in each direction; prepare a uniform slurry for later use.

[0059] S4. A Si-Cr-Ti-Al slurry coating was prepared on the niobium alloy surface treated in step S1 using a spraying method. After natural drying and vacuum furnace drying, the natural drying time was 2 days. The vacuum furnace drying adopted a stepped heating method, holding at 40℃ for 0.5h, then raising the temperature to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it was sent to a vacuum sintering furnace for sintering. During sintering, the temperature was raised from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain a Si-Cr-Ti-Al inner coating with a thickness of 25μm, which was then set aside for later use.

[0060] S5. The sample processed in step S4 is coated with MoSi2-Al-SiC slurry using a spraying method. It is then subjected to natural drying and vacuum furnace drying. The natural drying time is 2 days. The vacuum furnace drying adopts a stepped heating method, holding at 40℃ for 0.5h, then heating to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it is sent to a vacuum sintering furnace for sintering. During sintering, the temperature is increased from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain the MoSi2-Al-SiC outer coating with a thickness of 75μm.

[0061] Example 5

[0062] A method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy includes the following steps:

[0063] S1. Use 200-2000# sandpaper to rough grind the niobium alloy surface, then rinse with clean water, and then use alkaline solution, pickling solution and anhydrous ethanol for ultrasonic cleaning in sequence. Finally, blow dry and set aside for use.

[0064] S2. The Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder are pre-ground using a planetary ball mill. The particle size of the Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder after pre-grinding is 10-40 μm. They are then dried for later use.

[0065] S3. Mix the Si powder, Cr powder, Ti powder, and Al powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of Si powder is 40wt%, the content of Cr powder is 25wt%, the content of Ti powder is 15wt%, and the content of Al powder is 15wt%; add 3wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix the MoSi2 powder, Al powder, and SiC powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of MoSi2 powder is 80wt%, the content of Al powder is 5wt%, and the content of SiC powder is 5wt%; add 3wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix them separately using a high-energy planetary ball mill, with a ball-to-material ratio of 20:1, a rotation speed of 300 r / min, and a mixing time of 24 h, including 12 h in each direction; prepare a uniform slurry for later use.

[0066] S4. A Si-Cr-Ti-Al slurry coating was prepared on the niobium alloy surface treated in step S1 using a spraying method. After natural drying and vacuum furnace drying, the natural drying time was 2 days. The vacuum furnace drying adopted a stepped heating method, holding at 40℃ for 0.5h, then raising the temperature to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it was sent to a vacuum sintering furnace for sintering. During sintering, the temperature was raised from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain a Si-Cr-Ti-Al inner coating with a thickness of 55μm, which was then set aside for later use.

[0067] S5. The sample processed in step S4 is coated with MoSi2-Al-SiC slurry using a spraying method. It is then subjected to natural drying and vacuum furnace drying. The natural drying time is 2 days. The vacuum furnace drying adopts a stepped heating method, holding at 40℃ for 0.5h, then heating to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it is sent to a vacuum sintering furnace for sintering. During sintering, the temperature is increased from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain the MoSi2-Al-SiC outer coating with a thickness of 15μm.

[0068] Example 6

[0069] A method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy includes the following steps:

[0070] S1. Use 200-2000# sandpaper to rough grind the niobium alloy surface, then rinse with clean water, and then use alkaline solution, pickling solution and anhydrous ethanol for ultrasonic cleaning in sequence. Finally, blow dry and set aside for use.

[0071] S2. The Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder are pre-ground using a planetary ball mill. The particle size of the Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder after pre-grinding is 10-40 μm. They are then dried for later use.

[0072] S3. Mix the Si powder, Cr powder, Ti powder, and Al powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of Si powder is 45wt%, the content of Cr powder is 20wt%, the content of Ti powder is 15wt%, and the content of Al powder is 15wt%; add 3wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix the MoSi2 powder, Al powder, and SiC powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of MoSi2 powder is 80wt%, the content of Al powder is 10wt%, and the content of SiC powder is 5wt%; add 1wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix them separately using a high-energy planetary ball mill, with a ball-to-material ratio of 20:1, a rotation speed of 300 r / min, and a mixing time of 24 h, including 12 h in each direction; prepare a uniform slurry for later use.

[0073] S4. A Si-Cr-Ti-Al slurry coating was prepared on the niobium alloy surface treated in step S1 using a spraying method. After natural drying and vacuum furnace drying, the natural drying time was 2 days. The vacuum furnace drying adopted a stepped heating method, holding at 40℃ for 0.5h, then raising the temperature to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it was sent to a vacuum sintering furnace for sintering. During sintering, the temperature was raised from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain a Si-Cr-Ti-Al inner coating with a thickness of 100μm, which was then set aside for later use.

[0074] S5. The sample processed in step S4 is coated with MoSi2-Al-SiC slurry using a spraying method. It is then subjected to natural drying and vacuum furnace drying. The natural drying time is 2 days. The vacuum furnace drying adopts a stepped heating method, holding at 40℃ for 0.5h, then heating to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it is sent to a vacuum sintering furnace for sintering. During sintering, the temperature is increased from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain the MoSi2-Al-SiC outer coating with a thickness of 50μm.

[0075] Example 7

[0076] A method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy includes the following steps:

[0077] S1. Use 200-2000# sandpaper to rough grind the niobium alloy surface, then rinse with clean water, and then use alkaline solution, pickling solution and anhydrous ethanol for ultrasonic cleaning in sequence. Finally, blow dry and set aside for use.

[0078] S2. The Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder are pre-ground using a planetary ball mill. The particle size of the Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder after pre-grinding is 10-40 μm. They are then dried for later use.

[0079] S3. Mix the Si powder, Cr powder, Ti powder, and Al powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of Si powder is 50wt%, the content of Cr powder is 15wt%, the content of Ti powder is 15wt%, and the content of Al powder is 15wt%; add 3wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix the MoSi2 powder, Al powder, and SiC powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of MoSi2 powder is 80wt%, the content of Al powder is 10wt%, and the content of SiC powder is 5wt%; add 2.5wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix them separately using a high-energy planetary ball mill, with a ball-to-material ratio of 20:1, a rotation speed of 300 r / min, and a mixing time of 24 h, including 12 h in each direction; prepare a uniform slurry for later use.

[0080] S4. A Si-Cr-Ti-Al slurry coating was prepared on the niobium alloy surface treated in step S1 using a spraying method. After natural drying and vacuum furnace drying, the natural drying time was 2 days. The vacuum furnace drying adopted a stepped heating method, holding at 40℃ for 0.5h, then raising the temperature to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it was sent to a vacuum sintering furnace for sintering. During sintering, the temperature was raised from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain a Si-Cr-Ti-Al inner coating with a thickness of 45μm, which was then set aside for later use.

[0081] S5. The sample processed in step S4 is coated with MoSi2-Al-SiC slurry using a spraying method. It is then subjected to natural drying and vacuum furnace drying. The natural drying time is 2 days. The vacuum furnace drying adopts a stepped heating method, holding at 40℃ for 0.5h, then heating to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it is sent to a vacuum sintering furnace for sintering. During sintering, the temperature is increased from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain the MoSi2-Al-SiC outer coating with a thickness of 110μm.

[0082] Example 8

[0083] A method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy includes the following steps:

[0084] S1. Use 200-2000# sandpaper to rough grind the niobium alloy surface, then rinse with clean water, and then use alkaline solution, pickling solution and anhydrous ethanol for ultrasonic cleaning in sequence. Finally, blow dry and set aside for use.

[0085] S2. The Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder are pre-ground using a planetary ball mill. The particle size of the Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder after pre-grinding is 10-40 μm. They are then dried for later use.

[0086] S3. Mix the Si powder, Cr powder, Ti powder, and Al powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of Si powder is 45wt%, the content of Cr powder is 15wt%, the content of Ti powder is 15wt%, and the content of Al powder is 15wt%; add 5wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix the MoSi2 powder, Al powder, and SiC powder treated in step S2 in a certain proportion, and add appropriate amounts of diluent and binder, wherein: the content of MoSi2 powder is 80wt%, the content of Al powder is 10wt%, and the content of SiC powder is 5wt%; add 3.5wt% polyvinyl butyral, and the remainder is anhydrous ethanol; mix them separately using a high-energy planetary ball mill, with a ball-to-material ratio of 20:1, a rotation speed of 300 r / min, and a mixing time of 24 h, including 12 h in each direction; prepare a uniform slurry for later use.

[0087] S4. A Si-Cr-Ti-Al slurry coating was prepared on the niobium alloy surface treated in step S1 using a spraying method. After natural drying and vacuum furnace drying, the natural drying time was 2 days. The vacuum furnace drying adopted a stepped heating method, holding at 40℃ for 0.5h, then raising the temperature to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it was sent to a vacuum sintering furnace for sintering. During sintering, the temperature was raised from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain a Si-Cr-Ti-Al inner coating with a thickness of 50μm, which was then set aside for later use.

[0088] S5. The sample processed in step S4 is coated with MoSi2-Al-SiC slurry using a spraying method. It is then subjected to natural drying and vacuum furnace drying. The natural drying time is 2 days. The vacuum furnace drying adopts a stepped heating method, holding at 40℃ for 0.5h, then heating to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h. After that, it is sent to a vacuum sintering furnace for sintering. During sintering, the temperature is increased from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min and held for 0.5h to obtain the MoSi2-Al-SiC outer coating with a thickness of 50μm.

[0089] Comparative Example 1

[0090] The difference from Example 1 is that only a Si-Cr-Ti-Al coating was prepared.

[0091] The surface and cross-sectional SEM images of the niobium alloy coating prepared in this comparative example are shown below. Figure 2 As shown (the left side is the surface SEM image, and the right side is the cross-sectional SEM image), the single Si-Cr-Ti-Al coating has no cracks on its surface and is relatively smooth; the coating has good adhesion to the substrate and the coating is relatively dense inside.

[0092] Comparative Example 2

[0093] The difference from Example 1 is that only the MoSi2-Al-SiC coating was prepared.

[0094] The surface and cross-sectional SEM images of the niobium alloy coating prepared in this comparative example are shown below. Figure 3 As shown (the left side is the surface SEM image, and the right side is the cross-sectional SEM image), the surface of the single MoSi2-Al-SiC coating is relatively smooth, without cracks, and relatively dense; the coating and the substrate have good adhesion.

[0095] The niobium alloys with surface coatings prepared in the above embodiments and comparative examples were subjected to static oxidation resistance tests in air at 1700°C. The holding time was 10-20 hours, with a 1-hour increment. The integrity of the coating after oxidation and the absence of cracks were used as the criteria for judging the oxidation resistance life. The results are shown in the table below. It can be seen that the oxidation resistance life of the double-layer anti-oxidation coating on the surface of the niobium alloy of the present invention is ≥15 hours, and the oxidation resistance life of the single coating is ≤13 hours.

[0096] Antioxidant lifespan (h) Example 1 16h Example 2 16h Example 3 17h Example 4 15h Example 5 18h Example 6 15h Example 7 20h Example 8 19h Comparative Example 1 13h Comparative Example 2 11h

[0097] As can be seen from the above embodiments and comparative examples, the present invention sequentially prepares a Si-Cr-Ti-Al inner coating and a MoSi2-Al-SiC outer coating on the surface of a niobium alloy. The SiC in the outer coating acts as a reinforcement, while Al and MoSi2 form a relatively continuous Al2O3 and SiO2 protective film. The inner coating acts as an intermediate layer, in which Cr, Si, Ti and Al come into contact with the infiltrated oxygen, and the generated Cr2O3, SiO2, TiO2 and Al2O3 can greatly reduce the oxygen permeability and improve the oxidation resistance of the coating. This composite coating significantly improves the resistance of the niobium alloy to high-temperature oxidation.

[0098] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy, characterized in that, Includes the following steps: S1. Use sandpaper to rough grind the surface of the niobium alloy, then rinse with water, and then use alkaline solution, pickling solution and anhydrous ethanol for ultrasonic cleaning in sequence. Finally, blow dry and set aside for use. S2. The Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder are initially ground using a planetary ball mill, and then dried for later use. S3. Mix the Si powder, Cr powder, Ti powder, and Al powder treated in step S2 in a certain proportion. Mix the MoSi2 powder, Al powder, and SiC powder treated in step S2 in a certain proportion. Add appropriate amounts of diluent and binder respectively, and then mix using a high-energy planetary ball mill to prepare a uniform slurry for later use. The mass ratio of Si powder, Cr powder, Ti powder, and Al powder is (30~50):(10~30):15:15; the mass ratio of MoSi2 powder, Al powder, and SiC powder is (70~80):(5~30):

5. S4. A Si-Cr-Ti-Al slurry coating is prepared on the niobium alloy surface treated in step S1 by spraying. After natural drying and vacuum furnace drying, it is sent to a vacuum sintering furnace for sintering to obtain a Si-Cr-Ti-Al inner coating for later use. S5. The sample processed in step S4 is coated with MoSi2-Al-SiC slurry by spraying. The sample is then dried naturally and in a vacuum furnace, and then sintered in a vacuum sintering furnace to obtain the MoSi2-Al-SiC outer coating. The double-layer anti-oxidation coating on the surface of the niobium alloy has a static anti-oxidation life of more than 15 hours in air at 1700℃.

2. The method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to claim 1, characterized in that, In step S2, the particle size of the Si powder, Cr powder, Ti powder, Al powder, MoSi2 powder, and SiC powder after preliminary grinding is 10~40μm.

3. The method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to claim 1, characterized in that, In step S3, the ball-to-material ratio of the ball mill is 20:1, the rotation speed is 300 r / min, and the mixing time of the ball mill is 24 h, including 12 h for each of the forward and reverse rotation.

4. The method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to claim 1, characterized in that, In step S3, the adhesive is polyvinyl butyral and the diluent is anhydrous ethanol.

5. The method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to claim 1, characterized in that, In steps S4 and S5, the natural drying time is 2 days; the vacuum furnace drying adopts a stepped heating method, holding at 40℃ for 0.5h, then raising the temperature to 65℃ and holding for 0.5h, and finally holding at 100℃ for 1.0h.

6. The method for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy according to claim 1, characterized in that, In steps S4 and S5, during sintering, the temperature is increased from 400℃ to the sintering holding temperature of 1570℃ at a heating rate of 10℃ / min, and held for 0.5h.

7. A double-layer anti-oxidation coating on the surface of a niobium alloy, characterized in that, The coating was prepared using the method described in any one of claims 1-6 for preparing a double-layer anti-oxidation coating on the surface of a niobium alloy.

8. The double-layer anti-oxidation coating on the surface of the niobium alloy according to claim 7, characterized in that, The double-layer anti-oxidation coating on the surface of the niobium alloy includes a Si-Cr-Ti-Al inner coating and a MoSi2-Al-SiC outer coating. The thickness of the Si-Cr-Ti-Al inner coating is 10~100μm, and the thickness of the MoSi2-Al-SiC outer coating is 15~110μm.

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