Wear-resistant and high-temperature-resistant plasma spraying metal ceramic composite coating and preparation method thereof

Abstract

The invention discloses a wear-resistant and high-temperature-resistant plasma spraying metal ceramic composite coating and a preparation method thereof.The preparation method of the wear-resistant and high-temperature-resistant plasma spraying metal ceramic composite coating comprises the following steps that S1, the surface of a base body is subjected to oil removal cleaning and sand blasting pretreatment; s2, spraying a bonding layer on the surface of the matrix treated in the step S1 by using cobalt-based metal powder; s3, metal ceramic mixed powder is used for spraying a transition layer; s4, spraying the ceramic layer with temperature-resistant ceramic powder; s5, using wear-resistant ceramic powder to spray a wear-resistant ceramic layer; s6, hole sealing treatment is conducted on the coating treated in the step S5 through a hole sealing agent; and S7, the coating treated in the step S6 is subjected to heat treatment, and the metal ceramic composite coating is obtained. The four-layer gradient structure design of the bonding layer, the transition layer, the temperature-resistant ceramic layer and the wear-resistant ceramic layer is adopted, the problems of interlayer stress concentration and stripping caused by the single structure of a traditional coating are effectively solved, and the overall bonding strength and thermal cycling stability of the coating are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal coatings, and particularly to a wear-resistant and high-temperature-resistant plasma-sprayed metal-ceramic composite coating and a preparation method thereof. Background Art

[0002] Due to their excellent wear resistance, high-temperature resistance, and corrosion resistance, metal-ceramic composite coatings have been widely used in high-temperature and high-wear environments such as aerospace, nuclear energy industry, and metallurgy. At present, the methods for preparing metal-ceramic composite coatings mainly include plasma spraying, high-velocity oxy-fuel spraying, laser cladding, etc. Among them, plasma spraying technology has become one of the main methods for preparing metal-ceramic composite coatings due to its advantages such as flexible process, wide applicability, and relatively low cost. Existing plasma-sprayed metal-ceramic composite coatings usually adopt a single coating structure or a simple double-layer structure, such as the combination of a cobalt-based metal layer and a ZrO 2 ceramic layer, which has improved the surface properties of the substrate material to a certain extent.

[0003] However, the existing plasma-sprayed metal-ceramic composite coatings have various deficiencies. First, coatings with a single structure or a simple double-layer structure are prone to interlayer peeling or fracture in high-temperature and high-wear environments, resulting in coating failure; second, the bonding strength of traditional coatings is insufficient, and fatigue cracks are likely to occur under thermal cycling and mechanical impact conditions; third, the component design of existing coatings is not reasonable enough to meet the requirements of high-temperature resistance and wear resistance simultaneously; in addition, the multi-porous structure inside the coating makes it easy to be oxidized in a high-temperature environment, further reducing the service life and reliability of the coating. These problems seriously restrict the application of metal-ceramic composite coatings under harsh working conditions.

[0004] Therefore, it is urgent to develop a new type of metal-ceramic composite coating and a preparation method thereof. The coating should have excellent high-temperature stability and wear resistance, high interlayer bonding strength, and a dense internal structure, and be able to work stably for a long time in high-temperature and high-wear environments. At the same time, its preparation method should have good controllability and repeatability, be able to meet the requirements of different substrate materials and working environments, and provide a reliable technical solution for the surface protection of components under high-temperature and high-wear conditions. Summary of the Invention

[0005] The purpose of the present invention is to provide a wear-resistant and high-temperature-resistant plasma-sprayed metal-ceramic composite coating and a preparation method thereof to solve the problems existing in the prior art as mentioned in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A preparation method of a wear-resistant and high-temperature-resistant plasma-sprayed metal-ceramic composite coating, the method comprising the following steps:

[0008] S1. Degrease, clean and perform sandblasting pretreatment on the substrate surface;

[0009] S2. Spray a bonding layer on the substrate surface treated in step S1 using cobalt-based metal powder;

[0010] S3. Spray a transition layer using a cermet mixed powder;

[0011] S4. Spray a ceramic layer using a heat-resistant ceramic powder;

[0012] S5. Spray a wear-resistant ceramic layer using a wear-resistant ceramic powder;

[0013] S6. Perform hole sealing treatment on the coating treated in step S5 using a hole sealer;

[0014] S7. Heat-treat the coating treated in step S6 to obtain a cermet composite coating.

[0015] Preferably, the raw materials used in the coating include the following components, and all powder particle sizes are < 100 μm:

[0016] a) Cobalt-based metal powder, the composition of which is by weight percentage: Co 50 - 70%, Cr 20 - 35%, W 1 - 20%;

[0017] b) Heat-resistant ceramic powder, the composition of which is by weight percentage: CaO 60 - 70%, SiO 2 25 - 35%, CeO 2 < 5%;

[0018] c) Cermet mixed powder, which is composed of the above cobalt-based metal powder and ceramic strengthening powder mixed in a mass ratio of 1:1;

[0019] d) Wear-resistant ceramic powder, which is composed of ZrO 2 -Y 2 O 3 Composition, where Y 2 O 3 Content ≤ 10%.

[0020] Preferably, in step S1, the surface roughness Ra of the workpiece after sandblasting pretreatment is 6 - 10.

[0021] Preferably, in step S2, the gas flow rate during spraying is 30 - 50 L / min, the powder feeding rate is 15 - 60 g / min, the spraying distance is 100 - 130 mm, and the spraying angle is 30 - 90°.

[0022] Preferably, the gas includes Ar and H 2 , with Ar as the main gas and carrier gas, and H 2 As the auxiliary gas.

[0023] Preferably, the sealing agent in the step S6 is a water-based SiO 2 sealing agent.

[0024] Preferably, for the heat treatment in the step S7, the heating rate is < 5 °C / min and it is kept at 200 °C for 2 h.

[0025] A wear-resistant and high-temperature-resistant plasma-sprayed metal-ceramic composite coating prepared by the above method.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1) This application adopts a four-layer gradient structure design of a bonding layer, a transition layer, a temperature-resistant ceramic layer, and a wear-resistant ceramic layer, effectively solving the problems of interlayer stress concentration and peeling caused by the single structure of traditional coatings. The composition gradually changes between the functional layers, achieving a smooth transition from the metal matrix to the ceramic surface layer, greatly improving the overall bonding strength and thermal cycle stability of the coating. The cobalt-based metal powder as the bonding layer provides excellent bonding performance, the metal-ceramic mixed powder as the transition layer provides good transition characteristics, the CaO-SiO 2 series temperature-resistant ceramic layer provides excellent high-temperature stability, and the ZrO 2 -Y 2 O 3 wear-resistant ceramic layer provides excellent wear resistance. This multi-layer material combination design enables the coating to simultaneously have the characteristics of high temperature resistance and wear resistance, and is suitable for more demanding working environments;

[0028] 2) This application optimizes the design of key parameters such as gas flow rate, powder feeding rate, spraying distance, and angle during the plasma spraying process to ensure the denseness and uniformity of the coating. In particular, the combination of using Ar as the main gas and carrier gas and H 2 as the auxiliary gas provides ideal conditions for the full melting and good deposition of the powder. In addition, the present invention uses a water-based SiO 2 sealing agent to perform hole sealing treatment on the coating and controls the heating rate for heat treatment, effectively eliminating the micropores and residual stress inside the coating, and further improving the denseness and oxidation resistance of the coating;

[0029] 3) The cermet composite coating prepared in this application has excellent high-temperature resistance (it can work in a high-temperature environment for a long time), outstanding wear resistance (the wear rate is significantly reduced), good bonding strength (not easy to peel and fall off), and excellent oxidation resistance (extends the service life). The preparation method of the present invention is simple to operate, the process is stable and controllable, and it can be applied to the surfaces of substrates with various shapes and materials, having good industrial application prospects and popularization value. This method can flexibly adjust the thickness and component ratio of each layer according to actual needs to meet the special requirements under different working conditions, providing a new technical solution for the surface protection of components under high-temperature and high-wear conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flowchart of the preparation method of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0032] In the description of the invention, it should be noted that the execution order of the steps is not limited by the serial numbers. The order change of some steps, the synchronous execution of steps, the split execution of steps, etc. are all within the protection scope of this application.

[0033] Example 1

[0034] A preparation method of a wear-resistant and high-temperature-resistant plasma-sprayed cermet composite coating is as follows:

[0035] S1. Degrease, clean and perform sandblasting pretreatment on the surface of the K417 nickel-based superalloy substrate. First, ultrasonically clean the substrate surface with acetone and ethanol for 30 minutes, and then perform sandblasting treatment with brown fused alumina abrasive (particle size 60 mesh). The sandblasting pressure is 0.5 MPa, the sandblasting distance is 120 mm, the sandblasting time is 2 minutes, and the surface roughness Ra of the substrate after treatment is 8.3.

[0036] S2. Spray a bonding layer on the surface of the substrate processed in step S1 using cobalt-based metal powder. The composition of the cobalt-based metal powder is as follows by weight percentage: Co 60%, Cr 28%, W 12%, and the particle size is 45 - 75 μm. Using a plasma spraying device, the argon flow rate is 45 L / min, the hydrogen flow rate is 5 L / min, the powder feeding rate is 35 g / min, the spraying current is 550 A, the spraying voltage is 65 V, the spraying distance is 120 mm, and the spraying angle is 90°. Spray 6 passes to obtain a bonding layer with a thickness of 150 μm.

[0037] S3. Spray a transition layer using a cermet mixed powder. The cermet mixed powder is composed of cobalt-based metal powder (with the same composition as in S2) and Al 2 O 3 ceramic strengthening powder mixed in a mass ratio of 1:1, and the particle size is 45 - 90 μm. Using the same equipment, the argon flow rate is 42 L / min, the hydrogen flow rate is 6 L / min, the powder feeding rate is 40 g / min, the spraying current is 580 A, the spraying voltage is 68 V, the spraying distance is 110 mm, and the spraying angle is 85°. Spray 5 passes to obtain a transition layer with a thickness of 180 μm.

[0038] S4. Spray a ceramic layer using heat-resistant ceramic powder. The composition of the heat-resistant ceramic powder is as follows by weight percentage: CaO 66%, SiO 2 3 1%, CeO2 3%, and the particle size is 65 - 95 μm. Using the same equipment, the argon flow rate is 40 L / min, the hydrogen flow rate is 8 L / min, the powder feeding rate is 45 g / min, the spraying current is 600 A, the spraying voltage is 70 V, the spraying distance is 105 mm, and the spraying angle is 85°. Spray 7 passes to obtain a heat-resistant ceramic layer with a thickness of 220 μm.

[0039] S5. Spray a wear-resistant ceramic layer using wear-resistant ceramic powder. The wear-resistant ceramic powder is composed of ZrO 2 - Y 2 O 3 and the content of Y 2 O 3 is 8%, and the particle size is 50 - 85 μm. Using the same equipment, the argon flow rate is 38 L / min, the hydrogen flow rate is 10 L / min, the powder feeding rate is 42 g / min, the spraying current is 620 A, the spraying voltage is 72 V, the spraying distance is 100 mm, and the spraying angle is 80°. Spray 8 passes to obtain a wear-resistant ceramic layer with a thickness of 250 μm.

[0040] S6. Perform a sealing treatment on the coating processed in step S5 using a sealing agent. Use a water-based SiO 2 sealing agent (the content of SiO 2 is 30%), spray 2 times on the surface of the coating, with an interval of 30 minutes between each time, and naturally dry at room temperature for 4 hours.

[0041] S7. Heat-treat the coating processed in step S6. The heating rate is 3 °C / min. After heating to 200 °C, keep it for 2 hours, and then cool it to room temperature at the same rate to obtain a cermet composite coating with a total thickness of about 800 μm.

[0042] As an additional note:

[0043] 1) Bond strength test: Use the ASTM C633-13 standard method to test the bond strength between the coating and the substrate. The specific operation is as follows: Bond the coated specimen and the uncoated test cylinder with epoxy resin glue. After the glue is completely cured (cured at 80 °C for 8 hours), use a universal material testing machine to stretch it to separation at a constant rate (1 mm / min), record the maximum tensile load at fracture, and divide it by the cross-sectional area of the coating to obtain the bond strength value. The high-temperature bond strength test is carried out in a special high-temperature tensile device. The specimen is preheated to 800 °C and tested after keeping the temperature constant for 30 minutes. Each group of samples is tested 5 times and the average value is taken.

[0044] 2) Thermal shock resistance test: Use the cyclic thermal shock test method to evaluate the thermal shock resistance of the coating. Put the specimen into a high-temperature resistance furnace, heat it to 1000 °C at a rate of 10 °C / min, keep it for 10 minutes to make the temperature evenly distributed, and then immediately immerse it in deionized water at 25 ± 2 °C for rapid cooling for 30 seconds, and then take it out and air-dry it. Cycle this process, and regularly check the coating surface with a 40× microscope, and record the number of cycles when obvious cracks start to appear or the coating peels off. Each group of samples is tested with 3 parallel samples and the average value is taken.

[0045] 3) Wear resistance test: Use an HT-1000 high-temperature pin-on-disk wear testing machine to evaluate the wear resistance of the coating. Fix the coated specimen as the disk, and the counter-material is a GCr15 bearing steel ball with a diameter of 6 mm. Apply a load of 10 N, the sliding linear velocity is 0.5 m / s, and the sliding distance is 3600 m (the test time is about 2 hours). The high-temperature test is carried out in an 800 °C environment. The specimen is preheated for 30 minutes before the test to ensure uniform temperature. Weigh the specimen with a precision electronic balance (accuracy 0.1 mg) before and after each test, and combine the geometric dimensions of the wear track to calculate the volume wear rate (unit: mm 3 / N·m). Each group of samples is tested 3 times and the average value is taken.

[0046] 4) High-temperature oxidation test: The isothermal oxidation method was used to evaluate the oxidation resistance of the coating. Coating specimens with dimensions of 10 mm × 10 mm × 2 mm were ultrasonically cleaned with acetone and ethanol before the test, and weighed using a precision balance (accuracy 0.01 mg) after drying. The specimens were placed in a high-temperature box furnace and heated to 1100 °C at a rate of 5 °C / min, and held for 100 hours in an air atmosphere. After cooling to room temperature, they were weighed again. Calculate the oxidation weight gain per unit surface area (mg / cm 2 ). Three parallel samples were tested for each group of samples, and the average value was taken.

[0047] Performance tests were carried out on the wear-resistant and high-temperature-resistant plasma-sprayed cermet composite coating prepared in this example, and the results are as follows:

[0048]

[0049] Thus, according to the results in the above table, it can be seen that the cermet composite coating prepared by the above process has excellent comprehensive performance. Using the K417 nickel-based superalloy as the substrate and combining with the four-layer gradient structure design, the coating has good bonding strength at both room temperature and high temperature (48.5 MPa at room temperature and still 35.2 MPa at 800 °C). At the same time, the coating shows excellent thermal shock resistance (can withstand 28 thermal cycles) and wear resistance (the room temperature wear rate is only 3.2×10 -6 mm 3 / N·m), and the high-temperature oxidation weight gain is also low (1.6 mg / cm 2 ), which is mainly due to the optimized interlayer material transition, water-based SiO 2 sealing treatment and heat treatment process of controlling the heating rate, which reduce the internal defects of the coating and make the structure more dense. This coating is especially suitable for the surface protection of high-temperature components (such as aeroengines).

[0050] Example 2

[0051] A preparation method of a wear-resistant and high-temperature-resistant plasma-sprayed cermet composite coating, the specific steps are as follows:

[0052] S1. Degreasing cleaning and sandblasting pretreatment were carried out on the surface of the H13 steel substrate. First, the surface of the substrate was ultrasonically cleaned with an industrial detergent for 25 minutes, then cleaned with acetone and ethanol for 15 minutes each, and sandblasted with white corundum abrasive (grain size 80 mesh), the sandblasting pressure was 0.6 MPa, the sandblasting distance was 100 mm, and the sandblasting time was 3 minutes. The surface roughness Ra of the substrate after treatment was 7.5.

[0053] S2. Spray a bonding layer on the surface of the substrate processed in step S1 using cobalt-based metal powder. The composition of the cobalt-based metal powder by weight percentage is: Co 52%, Cr 32%, W 16%, and the particle size is 40 - 70 μm. Use a plasma spraying device with an argon flow rate of 40 L / min, a hydrogen flow rate of 6 L / min, a powder feeding rate of 30 g / min, a spraying current of 530 A, a spraying voltage of 63 V, a spraying distance of 125 mm, and a spraying angle of 85°. Spray 5 passes to obtain a bonding layer with a thickness of 130 μm.

[0054] S3 - S7. Carry out subsequent coating preparation under the same process conditions as in Example 1, and finally obtain a cermet composite coating with a total thickness of approximately 780 μm.

[0055] Perform the performance test on the wear-resistant and high-temperature-resistant plasma-sprayed cermet composite coating prepared in this example as in Example 1, and the results are as follows:

[0056]

[0057] Thus, according to the results in the above table, it can be seen that the cermet composite coating prepared on the H13 steel substrate, although slightly lower than that in Example 1 in terms of comprehensive performance, still exhibits excellent comprehensive performance. Its bonding strength (45.2 MPa at room temperature and 33.8 MPa at 800 °C), thermal shock performance (can withstand 25 thermal cycles), and wear resistance (room temperature wear rate of 3.5×10 -6 mm 3 / N·m) are far superior to traditional coatings. By adjusting the composition of the cobalt-based metal powder (increasing the content of Cr and W), the oxidation resistance and wear resistance of the coating are further improved. This coating can be applied to the surface protection of high-temperature working components in fields such as metallurgy and chemical engineering.

[0058] Example 3

[0059] A preparation method of a wear-resistant and high-temperature-resistant plasma-sprayed cermet composite coating, the specific steps are as follows:

[0060] S1. Perform degreasing cleaning and sandblasting pretreatment on the surface of the titanium alloy TC4 substrate. First, ultrasonically clean the surface of the substrate with acetone and ethanol for 20 minutes each, and then perform sandblasting treatment using brown fused alumina abrasive (particle size 70 mesh), with a sandblasting pressure of 0.55 MPa, a sandblasting distance of 110 mm, and a sandblasting time of 2.5 minutes. After treatment, the surface roughness Ra of the substrate is 9.2.

[0061] S2. Spray a bonding layer on the surface of the substrate processed in step S1 using cobalt-based metal powder. The composition of the cobalt-based metal powder is as follows by weight percentage: Co 68%, Cr 22%, W 10%, and the particle size is 45 - 85 μm. Using a plasma spraying device, the argon flow rate is 48 L / min, the hydrogen flow rate is 4 L / min, the powder feeding rate is 38 g / min, the spraying current is 560 A, the spraying voltage is 67 V, the spraying distance is 115 mm, and the spraying angle is 90°. Spray 7 passes to obtain a bonding layer with a thickness of 170 μm.

[0062] S3. Spray a transition layer using a cermet mixed powder. The cermet mixed powder is composed of cobalt-based metal powder (with the same composition as in S2) and ZrO 2 ceramic reinforcing powder mixed in a mass ratio of 1:1, and the particle size is 45 - 90 μm. Using the same equipment, the argon flow rate is 45 L / min, the hydrogen flow rate is 5 L / min, the powder feeding rate is 42 g / min, the spraying current is 585 A, the spraying voltage is 69 V, the spraying distance is 108 mm, and the spraying angle is 85°. Spray 6 passes to obtain a transition layer with a thickness of 200 μm.

[0063] S4 - S7. Carry out subsequent coating preparation under the same process conditions as in Example 1, and finally obtain a cermet composite coating with a total thickness of approximately 840 μm.

[0064] Perform the same performance tests as in Example 1 on the wear-resistant and high-temperature-resistant plasma-sprayed cermet composite coating prepared in this example. The results are as follows:

[0065]

[0066] Thus, according to the results in the above table, it can be seen that the cermet composite coating prepared on the titanium alloy TC4 substrate exhibits the most excellent comprehensive performance. Its bonding strength (50.3 MPa at room temperature and 37.6 MPa at 800 °C), thermal shock performance (can withstand 32 thermal cycles), and wear resistance (wear rate at room temperature is 2.8×10 -6 mm 3 / N·m, and 4.5×10 -6 mm 3 / N·m at 800 °C) are the best among all samples. This is mainly attributed to: 1) The optimized composition ratio of the cobalt-based bonding layer (the Co content is increased to 68%) provides better toughness and bonding; 2) Using ZrO2 ceramic as the strengthening phase in the transition layer provides better thermal expansion coefficient matching; 3) The multi-layer thickness design is more reasonable, and the total thickness reaches 840 μm, providing better durability for the coating. This coating is particularly suitable for high-temperature surface protection of titanium alloy components in the aerospace field.

[0067] Comparative Example 1

[0068] A preparation method of a traditional cermet double-layer coating is as follows:

[0069] S1. Degrease, clean and perform sandblasting pretreatment on the surface of the K417 nickel-based superalloy substrate, and the process conditions are the same as those in Example 1.

[0070] S2. Spray a metal layer on the surface of the substrate treated in step S1 using cobalt-based metal powder. The composition of the cobalt-based metal powder is by weight percentage: Co 60%, Cr 28%, W 12%, and the particle size is 45 - 75 μm. Using a plasma spraying device, the argon flow rate is 45 L / min, the hydrogen flow rate is 5 L / min, the powder feeding rate is 35 g / min, the spraying current is 550 A, the spraying voltage is 65 V, the spraying distance is 120 mm, and the spraying angle is 90°. Spray 10 passes to obtain a metal layer with a thickness of 300 μm.

[0071] S3. Directly spray a ceramic layer using ZrO 2 -Y 2 O 3 ceramic powder (Y 2 O 3 content is 8%), and the spraying process is the same as S5 in Example 1. Spray 15 passes to obtain a ceramic layer with a thickness of 450 μm.

[0072] S4. Do not perform sealing and heat treatment to obtain a traditional double-layer cermet coating with a total thickness of about 750 μm.

[0073] Perform performance tests on the cermet double-layer coating prepared in this comparative example in the same way as in Example 1, and the results are as follows:

[0074]

[0075]

[0076] From this, according to the results in the above table, it can be seen that the traditional double-layer cermet coating is significantly inferior to Examples 1 - 3 in terms of various performance indicators. Due to the lack of an intermediate layer, there is an obvious mismatch in materials and thermal expansion coefficients between the metal layer and the ceramic layer, resulting in a low bonding strength (only 32.6 MPa at room temperature and dropping to 18.4 MPa at 800 °C). At the same time, due to the lack of sealing and heat treatment, there are many pores and microcracks inside the coating, resulting in poor thermal shock performance (only able to withstand 8 thermal cycles), low wear resistance (room temperature wear rate as high as 7.5×10 -6 mm 3 / N·m) and poor oxidation resistance (oxidation weight gain as high as 5.8 mg / cm 2 ). This fully proves the necessity and effectiveness of the multi-layer gradient design and subsequent treatment process of the present invention.

[0077] Comparative Example 2

[0078] A preparation method of a three - layer cermet coating without gradient transition is as follows:

[0079] S1. Degreasing, cleaning and sandblasting pretreatment are carried out on the surface of the K417 nickel - based superalloy substrate, and the process conditions are the same as those in Example 1.

[0080] S2. A metal layer is sprayed on the surface of the substrate treated in step S1 using cobalt - based metal powder. The process conditions are the same as those of S2 in Example 1. Spray 6 passes to obtain a metal layer with a thickness of 150 μm.

[0081] S3. Directly use CaO - SiO 2 series temperature - resistant ceramic powder (with the same composition as S4 in Example 1) to spray a ceramic layer. The spraying process is the same as that of S4 in Example 1. Spray 10 passes to obtain a temperature - resistant ceramic layer with a thickness of 320 μm.

[0082] S4. Directly use ZrO 2 -Y 2 O 3 ceramic powder (Y 2 O 3 content is 8%) to spray a ceramic layer. The spraying process is the same as that of S5 in Example 1. Spray 10 passes to obtain a wear - resistant ceramic layer with a thickness of 320 μm.

[0083] S5. Use a water - based SiO 2 sealing agent for sealing treatment, but do not perform heat treatment, to obtain a three - layer cermet coating with a total thickness of about 790 μm.

[0084] Perform the same performance tests as in Example 1 on the wear - resistant and high - temperature - resistant plasma - sprayed cermet composite coating prepared in this comparative example. The results are as follows:

[0085]

[0086] Thus, according to the results in the above table, it can be seen that although the three - layer cermet coating without gradient transition has been improved compared with Comparative Example 1, its performance indicators are still significantly lower than those of Examples 1 - 3. Due to the lack of a metal - ceramic mixed transition layer, the inter - layer bonding performance is limited, and the bonding strength (38.5 MPa at room temperature and 24.6 MPa at 800 °C) is significantly lower than that of the examples. At the same time, due to the lack of heat treatment, the residual stress in the coating is large, resulting in poor thermal shock performance (only able to withstand 15 thermal cycles). In addition, the wear resistance (room - temperature wear rate is 5.2×10 -6 mm 3 / N·m) and oxidation resistance (oxidation weight gain is 3.5 mg / cm 2) is also significantly inferior to the examples. This further proves the importance of the gradient transition design and heat treatment process in this invention for improving the comprehensive performance of the coating.

[0087] As can be seen from the above examples and comparative examples:

[0088] 1. Bonding strength: The bonding strengths of Examples 1 - 3 are significantly higher than those of Comparative Examples 1 - 2, and can still maintain a relatively high bonding strength under high - temperature conditions. Among them, the bonding strength of Example 3 is the highest, which is mainly due to its multi - layer gradient structure design and optimized material composition formula. In contrast, the bonding strength of Comparative Example 1 is low due to the lack of a transition layer, especially under high - temperature conditions; although Comparative Example 2 has a three - layer structure, it lacks gradient transition and heat treatment process, and its bonding strength is also significantly lower than that of the examples.

[0089] 2. Thermal shock resistance: The number of thermal shock cycles of Examples 1 - 3 is significantly higher than that of Comparative Examples 1 - 2. Example 3 can withstand 32 thermal shock cycles without obvious cracks or spalling, while Comparative Example 1 can only withstand 8 cycles. This shows that the multi - layer gradient structure design and heat treatment process of this invention effectively improve the thermal shock resistance of the coating.

[0090] 3. Wear resistance: The wear rates of Examples 1 - 3 are significantly lower than those of Comparative Examples 1 - 2, especially under high - temperature conditions. The wear rate of Example 3 at 800 °C is only about 1 / 3 of that of Comparative Example 1, which fully proves that the coating of this invention has excellent wear - resistant performance and is especially suitable for use in high - temperature and high - wear environments.

[0091] 4. High - temperature oxidation performance: The high - temperature oxidation weight gain of Examples 1 - 3 is significantly lower than that of Comparative Examples 1 - 2. The oxidation weight gain of Example 3 is the lowest, only 1.4 mg / cm 2 , while the oxidation weight gain of Comparative Example 1 is as high as 5.8 mg / cm 2 . This shows that the sealing treatment and heat treatment process of this invention effectively improve the oxidation resistance of the coating.

[0092] In summary, the wear - resistant and high - temperature - resistant plasma - sprayed metal - ceramic composite coating of this invention is significantly superior to traditional metal - ceramic coatings in terms of bonding strength, thermal shock resistance, wear resistance, and oxidation resistance, and is especially suitable for applications in high - temperature and high - wear environments.

[0093] Although the present invention has been described in detail with reference to the foregoing examples and comparative examples, for those skilled in the art, they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a wear-resistant and high-temperature resistant plasma sprayed metal-ceramic composite coating, characterized in that: The method comprises the following steps: S1. Degreasing and cleaning the substrate surface and pre-treating it by sandblasting; S2. Spraying a bonding layer on the surface of the substrate treated in step S1 using a cobalt-based metal powder; S3. Use metal-ceramic mixed powder to spray the transition layer; S4. Spray the ceramic layer using temperature-resistant ceramic powder; S5. Use wear-resistant ceramic powder to spray a wear-resistant ceramic layer; S6. Using a sealing agent to seal the coating treated in step S5; S7. Heat-treating the coating treated in step S6 to obtain a metal-ceramic composite coating.

2. The method for preparing the wear-resistant and high-temperature-resistant plasma sprayed metal-ceramic composite coating according to claim 1, characterized in that: The raw materials used in the coating include the following components, all of which have a powder particle size of <100 μm: a) Cobalt-based metal powder, the composition of which is as follows by weight: Co 50-70%, Cr 20-35%, W 1-20%; b) Heat-resistant ceramic powder, the composition of which is as follows by weight: CaO 60-70%, SiO2 25-35%, CeO2<5%; c) metal-ceramic mixed powder, which is prepared by mixing the above-mentioned cobalt-based metal powder and ceramic reinforcement powder in a mass ratio of 1:1; d) Wear-resistant ceramic powder, composed of ZrO2-Y2O3, wherein the Y2O3 content is ≤10%.

3. The method for preparing the wear-resistant and high-temperature-resistant plasma sprayed metal-ceramic composite coating according to claim 1, characterized in that: In the step S1, the roughness Ra of the workpiece after sandblasting pretreatment is 6-10.

4. The method for preparing the wear-resistant and high-temperature-resistant plasma sprayed metal-ceramic composite coating according to claim 1, characterized in that: In the step S2, the gas flow rate during spraying is 30-50 L / min, the powder feeding rate is 15-60 g / min, the spraying distance is 100-130 mm, and the spraying angle is 30-90°.

5. The method for preparing the wear-resistant and high-temperature-resistant plasma sprayed metal-ceramic composite coating according to claim 4, characterized in that: The gas includes Ar and H2, with Ar serving as a main gas and a carrier gas, and H2 serving as an auxiliary gas.

6. The wear-resistant and high-temperature-resistant plasma sprayed metal-ceramic composite coating and the preparation method thereof according to claim 1, characterized in that: The sealing agent in step S6 is a water-based SiO2 sealing agent.

7. The wear-resistant and high-temperature-resistant plasma sprayed metal-ceramic composite coating and the preparation method thereof according to claim 1, characterized in that: The heat treatment in step S7 has a heating rate of <5°C / min and is kept at 200°C for 2h.

8. A wear-resistant and high-temperature-resistant plasma-sprayed metal-ceramic composite coating prepared by the method of any one of claims 1 to 7.

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