Ti-Al-C phase reinforced NiCrAlY composite coating, preparation method and application thereof

Abstract

This invention relates to the field of coating preparation technology, specifically to a Ti-Al-C phase-reinforced NiCrAlY composite coating, its preparation method, and its application. Ti-Al-C powder is obtained through granulation, sintering, and sieving. The coating raw materials consist of 50-70% Ti-Al-C powder and 30-50% metallic NiCrAlY. The composite coating is prepared on a substrate using atmospheric plasma spraying technology: current 420-480A, power 25-35kW, powder feed rate 18-24g / min, step size 3mm, main gas flow rate 35L / min, and spraying distance 120mm. This enables the application of Ni-based composite thick coatings in high-temperature wear environments and provides a low-cost method for preparing Ti-Al-C phase-reinforced NiCrAlY composite coatings.

Description

Technical Field

[0001] This invention relates to the field of coating preparation technology, specifically to a Ti-Al-C phase-reinforced NiCrAlY composite coating, its preparation method, and its application. Background Technology

[0002] Coal is my country's primary energy source, and coal-fired power generation will remain the main mode of electricity supply for a considerable period. Boilers, as crucial energy and carbon source conversion equipment, are vital for the stable development of the economy and society under the energy transition policy. During operation, power generation boilers are prone to problems such as ash adhesion and wear, which not only damage the pipe walls but also increase the risk of accidents such as pipe rupture.

[0003] Thermal spraying technology, as a commonly used method for preparing surface protective coatings, offers advantages such as simple spraying operation, high deposition efficiency, and high coating bonding strength, significantly improving the high-temperature wear resistance and extending the service life of products. Coatings for coal-fired boilers require materials with excellent high-temperature stability, high-temperature wear resistance, and good thermal conductivity. NiCrAlY coatings exhibit good high-temperature oxidation resistance, high-temperature stability, and good thermal conductivity. However, this coating has relatively low hardness, making the addition of reinforcing phases to improve its high-temperature wear resistance crucial. We propose Ti-Al-C as a reinforcing phase addition system. This material system is low-cost, and by adjusting the process, it can form a Ti2AlC phase with both thermal conductivity and wear resistance, as well as a high-hardness TiC reinforcing phase, during the spraying preparation process. Therefore, the preparation of a low-cost Ti-Al-C phase-reinforced NiCrAlY composite coating and its application in high-temperature wear environments have significant application value.

[0004] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of how to achieve the application of Ni-based composite thick coatings in high-temperature wear environments by strengthening NiCrAlY coatings with Ti-Al-C phase at low cost, and to provide a Ti-Al-C phase reinforced NiCrAlY composite coating, its preparation method and its application.

[0006] To achieve the above objectives, this invention discloses a method for preparing a Ti-Al-C phase-reinforced NiCrAlY composite coating, comprising the following steps:

[0007] S1, Ti powder, Al powder and graphite are mixed and stirred with polyvinyl alcohol and sodium hydroxymethyl cellulose to obtain a slurry;

[0008] S2, spray granulation of the slurry obtained in step S1 to obtain agglomerated powder, then vacuum sintering, and sieve and classify the agglomerated powder after vacuum sintering to obtain Ti-Al-C powder.

[0009] S3, mix the Ti-Al-C powder sieved in step S2 with NiCrAlY to obtain a mixed powder;

[0010] S4, the substrate is roughened by sandblasting;

[0011] S5, a composite coating is prepared by spraying mixed powder onto the substrate after roughening in step S4 using atmospheric plasma spraying technology.

[0012] In step S1, the particle size distribution range of Ti powder, Al powder and graphite powder is Ti: 15~45 μm, Al: 10 μm, C: 1~5 μm.

[0013] In step S1, the molar ratio of Ti:Al:C is 2:1:1.

[0014] In step S2, the sintering temperature of vacuum sintering is 610~640℃.

[0015] In step S2, the Ti-Al-C powder obtained by sieving and grading has a particle size of 25~71μm.

[0016] In step S3, the mass ratio of Ti-Al-C powder is 60%~80%.

[0017] In step S5, the process parameters for atmospheric plasma spraying technology are: current 420~480 A, power 25~35 kW, powder feeding rate 18~24 g / min, step distance 3 mm, main gas flow rate 35 L / min, and spraying distance 120 mm.

[0018] The present invention also discloses a Ti-Al-C phase-reinforced NiCrAlY composite coating prepared by the above preparation method and the application of such a Ti-Al-C phase-reinforced NiCrAlY composite coating in a high-temperature wear environment.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention adopts a Ti-Al-C phase-reinforced NiCrAlY composite coating and its high-temperature wear application. The preparation method is simple and the cost is low. The resulting coating is dense and tightly bonded to the substrate. During the coating preparation process, reinforcing phases such as MAX phase and TiC are formed in situ, which has good high-temperature wear performance. It realizes the application of Ni-based composite thick coating in high-temperature wear environment and provides a method for preparing Ti-Al-C phase-reinforced NiCrAlY composite coating at low cost. Attached Figure Description

[0020] Figure 1 The bar chart shows the bonding strength of the composite coatings obtained in the examples and Comparative Example 1;

[0021] Figure 2 The wear rate of the composite coatings obtained in Examples 1 and Comparative Example 1 is shown.

[0022] Figure 3 The XRD patterns of the composite coatings obtained in Examples 1 and 2 and Comparative Examples 3 are shown below.

[0023] Figure 4 The coating microhardness results are shown for Examples 1 and 2, and Comparative Examples 3.

[0024] Figure 5 The wear rate of the composite coatings obtained in Examples 1 and Comparative Examples 2 and 3 is shown.

[0025] Figure 6 The cross-sectional morphology of the composite coatings obtained in Example (a) and Comparative Example 4 (b) is shown.

[0026] Figure 7 The wear rate of the composite coatings obtained in Examples 1 and 2 (Comparative Example 4) is shown.

[0027] Figure 8 The coefficient of friction of the composite coatings obtained in Examples 1 and 2 (Comparative Example 5);

[0028] Figure 9 The wear rate of the composite coatings obtained in Examples 1 and 5 and Comparative Example 5 are shown.

[0029] Figure 10 The wear rate of the composite coatings obtained in Examples 1 and 2 (Comparative Example 6) is shown. Detailed Implementation

[0030] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings. Example

[0031] Step 1: Mix Ti powder, Al powder and graphite in a molar ratio of 2:1:1, and then mix with binder and dispersant to obtain slurry.

[0032] Step 2: Spray granulation of the slurry obtained in step S1 to obtain agglomerated powder, and then vacuum sintering at a temperature of 630℃. The agglomerated powder after vacuum sintering needs to be sieved and classified to obtain a particle size in the range of 25~71 μm.

[0033] Step 3: Mix the powder sieved in step S2 with NiCrAlY in a ratio of 60% Ti-Al-C powder and 40% metallic NiCrAlY powder, wherein the particle size of NiCrAlY powder is 15~45 μm.

[0034] Step 4: Roughen the substrate by sandblasting.

[0035] Step 5: Prepare a composite coating on the substrate using atmospheric plasma spraying technology. The process parameters are: current 460A, power 30 kW, powder feed rate 20 g / min, step size 3 mm, main gas flow rate 35 L / min, and spraying distance 120 mm.

[0036] Comparative Example 1

[0037] Step 1: Mix Ti powder, Al powder and graphite in a molar ratio of 2:1:1, and then mix with binder and dispersant to obtain slurry.

[0038] Step 2: Spray granulation of the slurry obtained in step S1 to obtain agglomerated powder, and then vacuum sintering at a temperature of 630℃. The agglomerated powder after vacuum sintering needs to be sieved and classified to obtain a particle size in the range of 25~71 μm.

[0039] Step 3: Mix the powder sieved in step S2 with NiCrAlY in a ratio of 80% Ti-Al-C powder and 20% metallic NiCrAlY powder, wherein the particle size of NiCrAlY powder is 15~45 μm.

[0040] Step 4: Roughen the substrate by sandblasting.

[0041] Step 5: Prepare a composite coating on the substrate using atmospheric plasma spraying technology. The process parameters are: current 460A, power 30 kW, powder feed rate 20 g / min, step size 3 mm, main gas flow rate 35 L / min, and spraying distance 120 mm.

[0042] Comparative Example 2

[0043] Step 1: Mix Ti powder, Al powder and graphite in a molar ratio of 2:1:1, and then mix with binder and dispersant to obtain slurry.

[0044] Step 2: Spray granulation of the slurry obtained in step S1 to obtain agglomerated powder, and then vacuum sintering at a temperature of 630℃. The agglomerated powder after vacuum sintering needs to be sieved and classified to obtain a particle size in the range of 25~71 μm.

[0045] Step 3: Mix the powder sieved in step S2 with NiCrAlY in a ratio of 40% Ti-Al-C powder and 60% metallic NiCrAlY powder, wherein the particle size of NiCrAlY powder is 15~45 μm.

[0046] Step 4: Roughen the substrate by sandblasting.

[0047] Step 5: Prepare a composite coating on the substrate using atmospheric plasma spraying technology. The process parameters are: current 460A, power 30 kW, powder feed rate 20 g / min, step size 3 mm, main gas flow rate 35 L / min, and spraying distance 120 mm.

[0048] Comparative Example 3

[0049] Step 1: Mix Ti powder, Al powder and graphite in a molar ratio of 2:1:1, and then mix with binder and dispersant to obtain slurry.

[0050] Step 2: Spray granulation of the slurry obtained in step S1 to obtain agglomerated powder, and then vacuum sintering at a temperature of 630℃. The agglomerated powder after vacuum sintering needs to be sieved and classified to obtain a particle size in the range of 25~71 μm.

[0051] Step 3: Mix the powder sieved in step S2 with NiCrAlY in a ratio of 20% Ti-Al-C powder and 80% metallic NiCrAlY powder, wherein the particle size of NiCrAlY powder is 15~45 μm.

[0052] Step 4: Roughen the substrate by sandblasting.

[0053] Step 5: Prepare a composite coating on the substrate using atmospheric plasma spraying technology. The process parameters are: current 460A, power 30 kW, powder feed rate 20 g / min, step size 3 mm, main gas flow rate 35 L / min, and spraying distance 120 mm.

[0054] Comparative Example 4

[0055] Step 1: Mix Ti powder, Al powder and graphite in a molar ratio of 2:1:1, and then mix with binder and dispersant to obtain slurry.

[0056] Step 2: Spray granulation of the slurry obtained in step S1 to obtain agglomerated powder, and then vacuum sintering at a temperature of 630℃. The agglomerated powder after vacuum sintering needs to be sieved and classified to obtain a particle size in the range of 25~71 μm.

[0057] Step 3: Mix the powder sieved in step S2 with NiCrAlY in a ratio of 60% Ti-Al-C powder and 40% metallic NiCrAlY powder, wherein the particle size of NiCrAlY powder is 15~45 μm.

[0058] Step 4: Roughen the substrate by sandblasting.

[0059] Step 5: Prepare a composite coating on the substrate using atmospheric plasma spraying technology. The process parameters are: current 460A, power 25 kW, powder feed rate 20 g / min, step size 3 mm, main gas flow rate 35 L / min, and spraying distance 120 mm.

[0060] Comparative Example 5

[0061] Step 1: Mix Ti powder, Al powder and graphite in a molar ratio of 2:1:1, and then mix with binder and dispersant to obtain slurry.

[0062] Step 2: Spray granulation of the slurry obtained in step S1 to obtain agglomerated powder, and then vacuum sintering at a temperature of 630℃. The agglomerated powder after vacuum sintering needs to be sieved and classified to obtain a particle size in the range of 25~71 μm.

[0063] Step 3: Mix the powder sieved in step S2 with NiCrAlY in a ratio of 60% Ti-Al-C powder and 40% metallic NiCrAlY powder, wherein the particle size of NiCrAlY powder is 15~45 μm.

[0064] Step 4: Roughen the substrate by sandblasting.

[0065] Step 5: Prepare a composite coating on the substrate using atmospheric plasma spraying technology. The process parameters are: current 460A, power 35 kW, powder feed rate 20 g / min, step size 3 mm, main gas flow rate 35 L / min, and spraying distance 120 mm.

[0066] Comparative Example 6

[0067] NiCrAlY coatings were prepared on the substrate using atmospheric plasma spraying technology. The process parameters were: current 460 A, power 30 kW, powder feed rate 20 g / min, step size 3 mm, main gas flow rate 35 L / min, and spraying distance 120 mm.

[0068] Figure 1 The bar chart shows the adhesion of the coating in the examples and Comparative Example 1. As can be seen from the figure, when the Ti-Al-C content is too high, the adhesion of the coating is poor, which affects the service stability of the coating.

[0069] Figure 2The bar chart shows the wear rate of the Example and Comparative Example 1 at 600°C. The wear rate of the Example is lower than that of Comparative Example 1, and its wear performance is better than that of the other comparative examples.

[0070] Figure 3 The XRD patterns of the coatings in Examples 1, 2, and 3 show that the MAX phase was formed in situ in Examples 1, with the main phases being TiC, Ni3Al, and Ti2AlC. However, in Comparative Example 2, due to the low content of Ti-Al-C, no Ti2AlC phase was found to be formed, and the main phase was Ni3Al. The absence of the Ti2AlC phase affected the high-temperature tribological properties of the coating.

[0071] Figure 4 The chart shows the hardness of the coatings in the Example 1 and Comparative Examples 2 and 3. The highest hardness value in the Example 1 is 661.1 HV. 0.2 The hardness of the coatings in Comparative Examples 2 and 3 was lower than that in the Example.

[0072] Figure 5 The bar chart shows the wear rate of the coatings in Examples 1, 2, and 3 at 600°C. Due to the formation of the Ti2AlC lubricating phase in the examples, the wear rate of the coatings was significantly reduced by approximately 0.74 × 10⁻⁶. -15 m 3 / (N·m).

[0073] Figure 6 The images show the cross-sectional morphology of the coatings in Example (a) and Comparative Example 4 (b). When the power is 30kW, the coating is dense, free of defects such as cracks, and tightly bonded to the substrate. When the power is 25kW, the coating contains more unmelted particles and a small number of pores.

[0074] Figure 7 The bar chart shows the wear rate of the coatings in Examples 1 and Comparative Example 4 at 600°C. Since the spraying power of the coating in Comparative Example 4 was 25kW, there were more unmelted particles in the coating, and its wear rate was higher than that of Examples 2.

[0075] Figure 8 The bar chart shows the friction coefficients of the Example and Comparative Example 5 at 600°C. The friction coefficient of the Example is significantly lower than that of Comparative Example 4.

[0076] Figure 9 The bar chart shows the wear rate of the Example and Comparative Example 5 at 600°C. The Example has the lowest wear rate and its wear performance is better than the other comparative examples.

[0077] Figure 10The bar chart shows the wear rate of the Example and Comparative Example 6 at 600°C. The Example has the lowest wear rate and its wear performance is better than the other comparative examples. Compared with the NiCrAlY coating of Comparative Example 6, the wear rate is significantly reduced. The present invention significantly improves the high-temperature friction and wear performance of the NiCrAlY coating and realizes the application of Ni-based alloy coatings in the field of high-temperature friction and wear.

[0078] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method for preparing a Ti-Al-C phase-reinforced NiCrAlY composite coating, characterized in that, Includes the following steps: S1, Ti powder, Al powder and graphite are mixed and stirred with polyvinyl alcohol and sodium hydroxymethyl cellulose to obtain a slurry; S2, spray granulation of the slurry obtained in step S1 to obtain agglomerated powder, then vacuum sintering, and sieve and classify the agglomerated powder after vacuum sintering to obtain Ti-Al-C powder. S3, the Ti-Al-C powder sieved in step S2 is mixed with NiCrAlY to obtain a mixed powder, wherein the mass percentage of Ti-Al-C powder in the mixed powder is 60%~80%; S4, roughen the substrate by sandblasting; S5. A composite coating is prepared by spraying mixed powder onto the roughened substrate in step S4 using atmospheric plasma spraying technology. The process parameters of atmospheric plasma spraying technology are: current 420~480 A, power 25~35 kW, powder feeding rate 18~24 g / min, step distance 3 mm, main gas flow rate 35 L / min, and spraying distance 120 mm. The main phases of the Ti-Al-C phase-reinforced NiCrAlY composite coating are TiC, Ni3Al and Ti2AlC.

2. The method for preparing a Ti-Al-C phase-reinforced NiCrAlY composite coating as described in claim 1, characterized in that, In step S1, the particle size distribution range of Ti powder, Al powder and graphite powder is Ti: 15~45 μm, Al: 10 μm, C: 1~5 μm.

3. The method for preparing a Ti-Al-C phase-reinforced NiCrAlY composite coating as described in claim 1, characterized in that, In step S1, the molar ratio of Ti:Al:C is 2:1:

1.

4. The method for preparing a Ti-Al-C phase-reinforced NiCrAlY composite coating as described in claim 1, characterized in that, In step S2, the sintering temperature of vacuum sintering is 610~640℃.

5. The method for preparing a Ti-Al-C phase-reinforced NiCrAlY composite coating as described in claim 1, characterized in that, In step S2, the Ti-Al-C powder obtained by sieving and grading has a particle size of 25~71μm.

6. A Ti-Al-C phase-reinforced NiCrAlY composite coating prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the Ti-Al-C phase-reinforced NiCrAlY composite coating as described in claim 6 in a high-temperature wear environment.

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