Method for preparing chromium carbide metal ceramic coating through thermal spraying technology and chromium carbide metal ceramic coating

Abstract

The invention relates to the technical field of metal ceramic layer preparation, and discloses a method for preparing a chromium carbide metal ceramic coating through a thermal spraying technology and the chromium carbide metal ceramic layer.The preparation method comprises the steps that CoCrMo powder and Cr3C2-NiCr powder are mixed and then added into a ball-milling tank, absolute ethyl alcohol and grinding balls are added into the ball-milling tank, and the mixture is stirred to be uniform; sealing the ball-milling tank and placing the ball-milling tank in a ball mill for ball-milling; and after ball milling is completed, a vacuum drying box is used for drying powder slurry in the ball milling tank, a screen is used for screening the dried powder, and therefore Cr3C2-NiCrCoMo composite powder with the uniform particle size distribution is obtained. And the Cr3C2-NiCrCoMo composite powder is sprayed on the surface of a preheated base body through a thermal spraying technology, and the chromium carbide metal ceramic coating is generated. The Cr3C2-NiCrCoMo chromium carbide metal ceramic coating prepared by the method disclosed by the invention has excellent high-temperature oxidation resistance, hardness and wear resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of metal ceramic layer preparation, and particularly relates to a method for preparing a chromium carbide metal ceramic coating by utilizing a thermal spraying technology and a chromium carbide metal ceramic layer. Background Art

[0002] Since the chromium carbide metal ceramic layer has good service performance at high temperatures, it is widely used in the strengthening and remanufacturing repair of the surface of turbine flow-through parts and rotor shafts, bearings, sealing bushes and other parts. The chromium carbide metal ceramic coating mainly contains Cr3C2 hard phase and metal bonding phase. The metal matrix composition is closely related to the high-temperature oxidation performance of the coating. By regulating the composition and content of multi-element alloying elements in the metal bonding phase of the coating, it is an effective method to improve the high-temperature oxidation performance of the coating.

[0003] Although chromium carbide metal ceramic coatings have many advantages, they still have some defects in high temperature oxidation resistance, hardness and wear resistance. Specifically, typical Cr3C2-NiCr coatings may experience oxidation of hard phase and bonding phase, decarburization of hard phase, shedding of oxide film, pores and cracks under working conditions above 815°C. These phenomena will lead to the degradation of the high temperature oxidation resistance, wear resistance and erosion resistance of the coating, thus limiting its application and service life under higher temperature conditions.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing a chromium carbide metal ceramic coating and a chromium carbide metal ceramic layer using thermal spraying technology, aiming to solve the problem that the existing chromium carbide metal ceramic layer has poor high temperature oxidation resistance, hardness and wear resistance.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a chromium carbide metal ceramic coating using thermal spraying technology, comprising the steps of:

[0008] CoCrMo powder and Cr3C2-NiCr powder are mixed and added into a ball mill, anhydrous ethanol and grinding balls are added into the ball mill, and then the ball mill is sealed and placed in a ball mill for ball milling;

[0009] After the ball milling is completed, the powder slurry in the ball mill is dried using a vacuum drying oven, and the dried powder is sieved using a sieve to obtain a Cr3C2-NiCrCoMo composite powder with uniform particle size distribution;

[0010] The Cr3C2-NiCrCoMo composite powder is sprayed on the surface of the preheated substrate by a thermal spraying process to generate a chromium carbide metal ceramic coating.

[0011] The method for preparing chromium carbide metal ceramic coating by thermal spraying technology comprises the following steps: in the step of mixing CoCrMo powder and Cr3C2-NiCr powder and adding the mixed powder into a ball mill, the mass ratio of the CoCrMo powder to the Cr3C2-NiCr powder is 1:5-10.

[0012] The method for preparing a chromium carbide metal ceramic coating using thermal spraying technology comprises the steps of adding anhydrous ethanol and grinding balls into a ball mill, and then sealing the ball mill and placing the ball mill in a ball mill for ball milling, wherein the ball-to-material ratio is 2:1, the ball mill speed is 100-200 r / min, and the ball milling time is 10-20 min.

[0013] The method for preparing a chromium carbide metal ceramic coating using thermal spraying technology, wherein, in the step of using a sieve to screen the dried powder, 320-mesh and 800-mesh sieves are used to screen the dried powder, thereby obtaining a Cr3C2-NiCrCoMo composite powder with a particle size distribution of 46:18:4 μm.

[0014] The method for preparing a chromium carbide metal ceramic coating by using thermal spraying technology, wherein the Cr3C2-NiCrCoMo composite powder is sprayed on the surface of a preheated substrate by a thermal spraying process to generate a chromium carbide metal ceramic coating, comprises the following steps:

[0015] Firstly, the surface of the substrate is degreased, and then the substrate is preheated at 200-250° C. to obtain a pretreated substrate;

[0016] The Cr3C2-NiCrCoMo composite powder is used to perform supersonic flame spraying on the surface of the pretreated substrate to generate a chromium carbide metal ceramic coating on the surface of the pretreated substrate.

[0017] The method for preparing a chromium carbide metal ceramic coating by using thermal spraying technology, wherein, in the step of supersonic flame spraying on the pretreated substrate surface, the spraying distance is 410-450mm and the powder feeding rate is 120-150g / min.

[0018] The method for preparing a chromium carbide metal ceramic coating by using thermal spraying technology, wherein, in the step of supersonic flame spraying on the surface of the pretreated substrate, the fuel during supersonic flame spraying is kerosene, and the flow rate is controlled to be 20-30L / min; the supporting gas is industrial oxygen, and the flow rate is 600-1000L / min; the powder feeding gas is industrial argon, and the flow rate is 6-10L / min.

[0019] A chromium carbide metal ceramic coating is prepared by the preparation method of the present invention.

[0020] Beneficial effects: The present invention utilizes thermal spraying technology to realize a high-quality and efficient preparation method of a chromium carbide metal ceramic coating, which, on the one hand, improves the high-temperature oxidation resistance, wear resistance and erosion resistance of the chromium carbide metal ceramic coating; on the other hand, the modification of the chromium carbide metal ceramic coating helps to improve the high-temperature service performance and service life of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A flow chart of a method for preparing a chromium carbide metal ceramic coating by using thermal spraying technology is shown in the present invention.

[0022] Figure 2 Schematic diagram of preparing Cr3C2-NiCrCoMo composite powder according to the present invention.

[0023] Figure 3 This is a microscopic morphology of the Cr3C2-NiCrCoMo composite powder prepared in Example 1 of the present invention.

[0024] Figure 4 This is a microscopic morphology of the Cr3C2-NiCrCoMo composite powder prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0025] The present invention provides a method for preparing a chromium carbide metal ceramic coating by thermal spraying technology and a chromium carbide metal ceramic layer. In order to make the purpose, technical scheme and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] See also Figure 1 , Figure 1 The present invention provides a method for preparing a chromium carbide metal ceramic coating by thermal spraying technology, as shown in the figure, which includes the following steps:

[0027] S100, mixing CoCrMo powder and Cr3C2-NiCr powder and adding them into a ball mill, adding anhydrous ethanol and grinding balls into the ball mill, and then sealing the ball mill and placing it in a ball mill for ball milling;

[0028] S200, after the ball milling is completed, the powder slurry in the ball mill is dried using a vacuum drying oven, and the dried powder is sieved using a sieve, thereby obtaining a Cr3C2-NiCrCoMo composite powder with uniform particle size distribution;

[0029] S300, using a thermal spraying process to spray the Cr3C2-NiCrCoMo composite powder onto the surface of the preheated substrate to generate a chromium carbide metal ceramic coating.

[0030] Specifically, if Figure 2 As shown, the two powders of CoCrMo and Cr3C2-NiCr are mixed evenly in a dry and clean environment at a mass ratio of 1:5-10. Mechanical stirring or manual stirring can be used to ensure that the two powders are fully in contact; then the mixed powder is poured into a ball mill, and then an appropriate amount of anhydrous ethanol is added as a dispersant, and then an appropriate amount of grinding balls are added. After the ball mill is sealed, it is placed in a ball mill. According to the characteristics of the powder and the required particle size, the ball-to-material ratio is set to 2:1, the ball mill speed is 100-200r / min, and the ball milling time is 10-20min. Set appropriate parameters such as ball milling time and speed for ball milling. During the ball milling process, the collision and friction between the grinding balls and the powder particles will refine the powder particles and mix them evenly;

[0031] After the ball milling is completed, the ball mill containing the powder slurry is placed in a vacuum drying oven, and the appropriate temperature and time are set for drying to remove anhydrous ethanol and other volatiles in the powder. The vacuum environment helps to speed up the drying speed and prevent the powder from oxidizing. After the drying is completed, the powder is screened using a sieve. The aperture of the sieve should be determined according to the particle size distribution of the required powder. During the screening process, large particles of powder will be retained by the sieve, while small particles of powder will fall into the collection container through the sieve. Through multiple screening and adjustment of the sieve aperture, a Cr3C2-NiCrCoMo composite powder with uniform particle size distribution can be obtained. As an example, in this embodiment, in the step of using a sieve to screen the dried powder, a 320-mesh and 800-mesh sieve is used to screen the dried powder, thereby obtaining a Cr3C2-NiCrCoMo composite powder with a particle size distribution of 46:18:4μm.

[0032] The substrate material to be sprayed is preheated. The preheating temperature should be determined according to the type, thickness and spraying process requirements of the substrate material. Preheating helps to increase the temperature of the substrate surface and enhance the bonding force between the coating and the substrate. The Cr3C2-NiCrCoMo composite powder is sprayed on the preheated substrate surface using a thermal spraying process. During the thermal spraying process, the powder particles are heated to a molten or semi-molten state and sprayed onto the substrate surface under the action of a high-speed airflow to form a coating. The thickness and uniformity of the coating can be controlled by adjusting the spraying parameters. As an example, the surface of the substrate is first degreased, and then the substrate is preheated at 200-250°C to obtain a pretreated substrate; the Cr3C2-NiCrCoMo composite powder is used to perform supersonic flame spraying on the surface of the pretreated substrate to generate a chromium carbide metal ceramic coating on the surface of the pretreated substrate. In the step of supersonic flame spraying on the surface of the pretreated substrate, the spraying distance is 410-450mm, the powder feeding rate is 120-150g / min, the fuel during supersonic flame spraying is kerosene, and the flow rate is controlled to be 20-30L / min; the supporting gas is industrial oxygen, and the flow rate is 600-1000L / min; the powder feeding gas is industrial argon, and the flow rate is 6-10L / min.

[0033] The Cr3C2-NiCrCoMo composite powder obtained by ball milling, mixing and screening in this embodiment has the characteristics of uniform particle size distribution and fine particles, which helps to improve the density and uniformity of the coating, thereby improving the hardness, wear resistance, corrosion resistance and other properties of the coating; preheating the substrate can increase the temperature of the substrate surface, so that the powder particles and the substrate surface can be better metallurgically bonded during the spraying process, thereby improving the bonding force between the coating and the substrate; the vacuum drying oven can quickly remove moisture and volatiles in the powder and shorten the drying time; the thermal spraying process is efficient and flexible and can adapt to the spraying requirements of substrate materials of different shapes and sizes; by optimizing process parameters such as ball milling, drying and screening, the utilization rate of the powder and the quality stability of the coating can be improved, thereby reducing production costs.

[0034] Compared with the Cr3C2-NiCr coating, the Cr3C2-NiCrCoMo chromium carbide metal ceramic coating prepared in this embodiment has the addition of Co and Mo elements, which can form a more stable oxide layer at high temperature, effectively inhibit the oxidation rate of the hard phase and the bonding phase in the coating, thereby improving the high temperature oxidation resistance of the coating; and the addition of Co and Mo can refine the microstructure of the coating, improve the hardness and wear resistance of the coating; in addition, these elements can also promote the formation of binary spinel phases (such as NiCr2O4 and CoCr2O4), and these spinel phases can further enhance the hardness and wear resistance of the coating. Obviously, the Cr3C2-NiCrCoMo chromium carbide metal ceramic coating prepared in this embodiment has significant advantages over the Cr3C2-NiCr ceramic coating in terms of high temperature oxidation resistance, hardness and wear resistance, and these advantages are mainly due to the improvement of the coating composition and microstructure by the addition of Co and Mo elements.

[0035] The present invention will be further explained below by means of specific embodiments:

[0036] Example 1

[0037] A method for preparing a chromium carbide metal ceramic coating comprises the following steps:

[0038] 1. Mix CoCrMo powder and Cr3C2-NiCr powder in a mass ratio of 1:9 and add them into a ball mill, add anhydrous ethanol and grinding balls into the ball mill, and then seal the ball mill and place it in a ball mill for ball milling. The ball-to-material ratio is 2:1, the ball mill speed is 150r / min, and the ball milling time is 15min;

[0039] After the ball milling is completed, the powder slurry in the ball mill is dried in a vacuum drying oven, and the dried powder is sieved using 320 mesh and 800 mesh sieves to obtain a Cr3C2-NiCrCoMo composite powder (denoted as NCC10) with a particle size distribution of 46:18:4 μm. The microscopic morphology is shown in the figure. Figure 3 As shown, its composition is 67.5% Cr3C2: 18% Ni: 7.29% Cr: 6.58% Co: 0.63% Mo;

[0040] The substrate surface is first degreased, and then the substrate is preheated at 200-250°C to obtain a pretreated substrate; the Cr3C2-NiCrCoMo composite powder is used to perform supersonic flame spraying on the surface of the pretreated substrate, the spraying distance is 420mm, the powder feeding rate is 130g / min, the fuel during supersonic flame spraying is kerosene, and the flow rate is controlled to be 25L / min; the combustion-supporting gas is industrial oxygen, and the flow rate is 800L / min; the powder feeding gas is industrial argon, and the flow rate is 8L / min, and finally a chromium carbide metal ceramic coating is generated on the surface of the pretreated substrate.

[0041] Example 2

[0042] A method for preparing a chromium carbide metal ceramic coating comprises the following steps:

[0043] 1. Mix CoCrMo powder and Cr3C2-NiCr powder in a mass ratio of 1.5:8.5 and add them to a ball mill. Add anhydrous ethanol and grinding balls to the ball mill. Then seal the ball mill and place it in a ball mill for ball milling. The ball-to-material ratio is 2:1, the ball mill speed is 110 r / min, and the ball milling time is 16 min.

[0044] After the ball milling is completed, the powder slurry in the ball mill is dried in a vacuum drying oven, and the dried powder is sieved using 320 mesh and 800 mesh sieves to obtain a Cr3C2-NiCrCoMo composite powder (denoted as NCC15) with a particle size distribution of 46:18:4 μm. The microscopic morphology is shown in the figure. Figure 4 As shown, its composition is 67.5% Cr3C2: 18% Ni: 7.29% Cr: 6.58% Co: 0.63% Mo;

[0045] The substrate surface is first degreased, and then the substrate is preheated at 200-250°C to obtain a pretreated substrate; the Cr3C2-NiCrCoMo composite powder is used to perform supersonic flame spraying on the surface of the pretreated substrate, the spraying distance is 440mm, the powder feeding rate is 140g / min, the fuel during supersonic flame spraying is kerosene, and the flow rate is controlled to be 26L / min; the supporting gas is industrial oxygen, and the flow rate is 900L / min; the powder feeding gas is industrial argon, and the flow rate is 9L / min, and finally a chromium carbide metal ceramic coating is generated on the surface of the pretreated substrate.

[0046] In this example, the NCC10 chromium carbide metal ceramic coating prepared in Example 1 was compared with the existing Cr3C2-NiCr coating in terms of high temperature oxidation resistance, hardness and wear resistance:

[0047] First, the NCC10 chromium carbide metal ceramic coating prepared in Example 1 and the existing Cr3C2-NiCr coating were subjected to constant temperature oxidation tests at 700°C, 800°C and 900°C, and the oxidation weight gain of the two after the same oxidation time was tested. The results showed that the oxidation weight gain of the NCC10 chromium carbide metal ceramic coating was reduced by 40% relative to the Cr3C2-NiCr coating, which shows that the addition of Co and Mo elements effectively enhances the high-temperature oxidation resistance of the coating. Compared with the Cr3C2-NiCr coating, the doped binary spinel phase (such as NiCr2O4 and CoCr2O4) has an inhibitory effect on ion diffusion, and the addition of nano CeO2 promotes the reaction between oxides and the formation of binary spinel phases, thereby enhancing the oxidation resistance of the coating.

[0048] Then, the hardness and wear resistance of the NCC10 chromium carbide metal ceramic coating prepared in Example 1 and the existing Cr3C2-NiCr coating were tested. The results showed that the hardness of the NCC10 chromium carbide metal ceramic coating was increased by 56% and the wear resistance was increased by 60% compared with the Cr3C2-NiCr coating. This is because the addition of Co and Mo can refine the microstructure of the coating and improve the hardness and wear resistance of the coating; in addition, these elements can also promote the formation of binary spinel phases (such as NiCr2O4 and CoCr2O4), and these spinel phases can further enhance the hardness and wear resistance of the coating.

[0049] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a chromium carbide metal ceramic coating using thermal spraying technology, characterized in that: Includes steps: CoCrMo powder and Cr3C2-NiCr powder are mixed and added into a ball mill, anhydrous ethanol and grinding balls are added into the ball mill, and then the ball mill is sealed and placed in a ball mill for ball milling; After the ball milling is completed, the powder slurry in the ball mill is dried using a vacuum drying oven, and the dried powder is sieved using a sieve to obtain a Cr3C2-NiCrCoMo composite powder with uniform particle size distribution; The Cr3C2-NiCrCoMo composite powder is sprayed on the surface of the preheated substrate by a thermal spraying process to generate a chromium carbide metal ceramic coating.

2. The method for preparing a chromium carbide metal ceramic coating by thermal spraying technology according to claim 1, characterized in that: In the step of mixing CoCrMo powder and Cr3C2-NiCr powder and adding them into a ball mill, the mass ratio of the CoCrMo powder to the Cr3C2-NiCr powder is 1:5-10.

3. The method for preparing a chromium carbide metal ceramic coating by thermal spraying technology according to claim 1, characterized in that: In the step of adding anhydrous ethanol and grinding balls into a ball mill, and then sealing the ball mill and placing it in a ball mill for ball milling, the ball-to-material ratio is 2:1, the ball mill speed is 100-200 r / min, and the ball milling time is 10-20 min.

4. The method for preparing a chromium carbide metal ceramic coating by thermal spraying technology according to claim 1, characterized in that: In the step of using a sieve to sieve the dried powder, 320-mesh and 800-mesh sieves are used to sieve the dried powder, thereby obtaining a Cr3C2-NiCrCoMo composite powder with a particle size distribution of 46:18:4 μm.

5. The method for preparing a chromium carbide metal ceramic coating by thermal spraying technology according to claim 1, characterized in that: The Cr3C2-NiCrCoMo composite powder is sprayed on the surface of the preheated substrate by a thermal spraying process to generate a chromium carbide metal ceramic coating, comprising the following steps: Firstly, the surface of the substrate is degreased, and then the substrate is preheated at 200-250° C. to obtain a pretreated substrate; The Cr3C2-NiCrCoMo composite powder is used to perform supersonic flame spraying on the surface of the pretreated substrate to generate a chromium carbide metal ceramic coating on the surface of the pretreated substrate.

6. The method for preparing a chromium carbide metal ceramic coating by thermal spraying technology according to claim 5, characterized in that: In the step of supersonic flame spraying the pretreated substrate surface, the spraying distance is 410-450 mm and the powder feeding rate is 120-150 g / min.

7. The method for preparing a chromium carbide metal ceramic coating by thermal spraying technology according to claim 5, characterized in that: In the step of supersonic flame spraying on the pretreated substrate surface, the fuel for supersonic flame spraying is kerosene, and the flow rate is controlled to be 20-30L / min; the supporting gas is industrial oxygen, and the flow rate is 600-1000L / min; the powder feeding gas is industrial argon, and the flow rate is 6-10L / min.

8. A chromium carbide metal ceramic coating, characterized in that: The method is prepared by any one of claims 1 to 7.

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