A method for preparing a coated doctor blade cermet wear resistant coating

Abstract

The application discloses a preparation method of a coating metal ceramic wear-resistant coating of a coating doctor blade, and comprises the following steps: weighing Ni20Cr powder and TiB2 powder to prepare a composite powder through high-energy ball milling; drying the NiCr-based ceramic powder prepared after the ball milling treatment; forming a composite coating on the surface of a substrate by using the treated NiCr-based ceramic powder through atmospheric plasma spraying; and forming a remelted coating on the surface of the substrate by using a laser remelting technology to perform a remelting treatment on the composite coating; wherein the remelting treatment comprises a preheating process and a remelting process. The application significantly improves the wear resistance of the coating, reduces the friction coefficient, realizes controllable deposition of the high-performance metal ceramic wear-resistant coating, and the coating prepared by the application can be applied to the surface of the coating doctor blade to improve the wear resistance and service life of the coating doctor blade.

Description

Technical Field

[0001] This invention belongs to the field of thermal spraying and surface engineering technology, and specifically relates to a method for preparing a wear-resistant coating for a coated scraper metal-ceramic. Background Technology

[0002] In the paper industry, coating blades play a crucial role, especially in the production of top-grade coated paper products, where they are highly valued by the global industry. The core function of this tool is to precisely distribute a uniform coating on a continuously moving paper surface to improve the smoothness and gloss of the paper. To continuously optimize production efficiency, manufacturers are constantly working to improve the structure of coating equipment and increase the operating speed of paper machines.

[0003] However, with the significant increase in paper machine operating speed, new challenges have emerged in the coating process. At high speeds, solid particles such as kaolin contained in the paper fibers and coating slurry cause severe impact and wear on the doctor blade edge, leading to a shortened doctor blade life and increasingly frequent replacements. This not only directly restricts overall production efficiency but also increases operating costs. Therefore, improving the doctor blade material formulation and developing a new generation of ceramic materials have become key approaches to solving this problem. The aim is to significantly improve the wear resistance and durability of coating doctor blades, thereby ensuring their performance stability and service life under high-speed production environments. Plasma spraying technology is a technique that uses a high-temperature plasma arc formed by ionized gas as the core heat source to heat powder materials to extremely high temperatures, causing them to enter a molten or semi-molten state. These high-temperature particles are then sprayed onto the substrate surface at a high speed of over 300 m / min. Upon contact with the relatively low-temperature substrate, they are instantly cooled and firmly deposited onto the substrate under the action of enormous kinetic energy and mechanical bonding force.

[0004] However, problems such as porosity, oxide inclusions, and insufficient adhesion between the coating and the substrate may occur during the spraying process. At the same time, due to the mismatch in the coefficients of thermal expansion between the ceramic coating and the metal substrate, coupled with the high brittleness of the ceramic itself, the coating is prone to cracking or even peeling off from the substrate during the rapid laser heating and subsequent rapid cooling process. This problem limits the service life of the coating after remelting. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a wear-resistant coating for a coated scraper metal ceramic.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing a wear-resistant coating for a doctor blade metal-ceramic coating, comprising, Ni20Cr powder and TiB2 powder were weighed and subjected to high-energy ball milling to prepare composite powder. After ball milling, the powder was dried to obtain dried NiCr-based ceramic powder. A composite coating is formed on the substrate surface using NiCr-based ceramic powder that has undergone atmospheric plasma spraying. Laser remelting technology is used to remelt the composite coating to form a remelted coating on the substrate surface; The remelting process includes preheating and remelting.

[0009] In a preferred embodiment of the preparation method described in this invention, the ball milling process is wherein the ball-to-material ratio is 1:1. The diameters of the large, medium, and small spheres are 5 mm, 3 mm, and 1 mm, respectively. The weight ratio of large, medium, and small balls is 2:3:5; The rotational speed is 600 r / min; The single operation time is 40 minutes; The dwell time after a single run is 10 minutes; the total running time is 8 hours.

[0010] In a preferred embodiment of the preparation method described in this invention, the surface treatment of the substrate includes: The substrate surface was ultrasonically cleaned with ethanol to remove oil stains; After cleaning, place the product in an oven to dry. Subsequently, the stainless steel surface to be sprayed was roughened by sandblasting with brown fused alumina sand with a particle size of 24 mesh. The roughness of the roughened particles was controlled at 2~8μm.

[0011] In a preferred embodiment of the preparation method described in this invention, the mass percentages of Ni20Cr powder and TiB2 powder are 70%–98% and 1%–15%, respectively. The average particle size of Ni20Cr powder is 45~85 μm, and the average particle size of TiB2 powder is 300 nm.

[0012] As a preferred embodiment of the preparation method described in this invention, the parameters of the plasma spraying are: current 500 A, Ar gas flow rate 40 L / min, H2 flow rate 5 L / min, powder feeding rate 40 g / min, spraying distance 100 mm, and spray gun translation speed 200 mm / s.

[0013] In a preferred embodiment of the preparation method described in this invention, the preheating process includes, The coating after atmospheric plasma spraying is placed on a temperature field-assisted heating platform, and the heating temperature is set to 300℃. The coating is then subjected to laser remelting treatment.

[0014] As a preferred embodiment of the preparation method described in this invention, the parameters of the remelting process include: selected power of 800W, 1000W and 1200W, scanning speed of 1200 mm / min, distance between laser head and coating of 600 mm, use of nozzle with diameter of 10 mm, introduction of argon gas at a flow rate of 6 L / min as protective gas, overlap rate of 50%, and after the coating is remelted, it is placed on a heating platform and slowly cooled to room temperature.

[0015] In a preferred embodiment of the preparation method described in this invention, the mass percentages of Ni and Cr in the Ni20Cr powder are 80% and 20%, respectively.

[0016] In a preferred embodiment of the preparation method described in this invention, the powder is dried for 1 hour at a temperature of 80°C.

[0017] As a preferred embodiment of the preparation method described in this invention, the substrate surface treatment further includes polishing the surface-mounted sample with 600, 1200, 2000, and 3000 grit wet sandpaper respectively, so that the surface roughness is less than 0.5 μm.

[0018] Beneficial effects of this invention: (1) The metal-ceramic composite coating prepared by the present invention has a dense structure, low porosity, good surface forming quality, and an average hardness greater than 390 HV. 0.1 Wear rate less than 11×10 -6 mm 3 / (N·m), the wear type changes from abrasive wear to adhesive wear; the coating after laser remelting treatment, by incorporating trace amounts of Ti, can effectively repair the loose areas left by atmospheric plasma spraying technology during the high-temperature laser heat treatment stage. This process benefits from the excellent sintering effect between the low-melting-point liquid phase and the high-melting-point solid phase promoted by Ti. During the remelting process, element B can inhibit grain growth and promote the formation of a finer and more uniform grain structure. Fine grains can improve the mechanical properties of materials, such as strength and toughness, because an increase in grain boundaries can effectively hinder dislocation movement.

[0019] (2) More importantly, laser remelting induces the formation of a Ti- and B-rich oxide layer within the coating. This oxide layer benefits from the entropy increase effect, resulting in a significant distortion of its crystal lattice. This distorted structure is not only a key factor in improving the material's hardness but also directly enhances the overall hardness performance of the coating. Therefore, by introducing hard phase particles TiB2, not only is the microstructure of the coating optimized, but the wear resistance and protective capabilities of the coating are further strengthened by enhancing its hardness. The inventive method of this invention significantly improves the wear resistance of the coating while reducing the coefficient of friction, enabling the controlled deposition of high-performance metal-ceramic wear-resistant coatings. The coating prepared by this invention can be applied to the surface of doctor blades to improve their wear resistance and service life. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments 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 these drawings without creative effort. Wherein: Figure 1 This is a microscopic morphology image of the coating after plasma spraying in Example 1 of the present invention.

[0021] Figure 2 This is a cross-sectional morphology diagram of the laser-remelted coating in Embodiment 1 of the present invention.

[0022] Figure 3 This is a schematic diagram showing the wear rate of remelted coatings with different powder ratios according to the present invention.

[0023] Figure 4 This is a schematic diagram showing the wear rate of the remelted coating under different laser powers according to the present invention.

[0024] Figure 5 This is a schematic diagram of the Vickers hardness of the remelted coatings with different powder ratios according to the present invention. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0028] The method for preparing the wear-resistant coating of a coated scraper metal-ceramic in this invention includes the following steps: The raw materials for the wear-resistant coating are TiB2 powder and Ni20Cr powder, wherein the mass percentages of TiB2 powder and Ni20Cr powder are 1-15% and 70%-98%, respectively, and the mass percentages of Ni and Cr in the Ni20Cr powder are 80% and 20%, respectively. The raw materials were ball-milled with a ball-to-material ratio of 1:1; the diameters of the large, medium, and small balls were 5 mm, 3 mm, and 1 mm, respectively; the weight ratio of the large, medium, and small balls was 2:3:5; the rotation speed was 600 r / min; the single run time was 40 min; the residence time after a single run was 10 min; and the total running time was 8 h. After ball milling, the raw materials were dried in an oven at 80℃ for 1 h.

[0029] Before spraying, the stainless steel substrate is treated. Specifically, the surface of the stainless steel substrate is ultrasonically cleaned with ethanol to remove oil and other impurities. After cleaning, it is placed in an oven for drying. Then, the surface of the stainless steel to be sprayed is roughened by sandblasting with brown corundum sand with a particle size of 24 mesh. The roughness of the roughened particles is controlled at 2-8 μm.

[0030] Pour the dried mixed powder into the powder feeding pipe, and adjust the powder feeding airflow so that the powder is just delivered to the center of the plasma arc flame. The process parameters for atmospheric plasma spraying are: current 500 A, Ar gas flow rate 40 L / min, H2 flow rate 5 L / min, powder feeding rate 40 g / min, spraying distance 100 mm, and spray gun translation speed 200 mm / s.

[0031] The parameters of the remelting process were set as follows: power of 800 W, 1000 W and 1200 W, scanning speed of 1200 mm / min, distance between laser head and coating of 600 mm, and overlap rate of 50%.

[0032] Porosity was calculated by extracting cross-sectional SEM images, revealing that the product coating has a dense structure and low porosity.

[0033] A ball-and-disc friction and wear test was conducted on the product coating. The paired ball was a Si3N4 ball with a diameter of 5 mm. The relative sliding speed was 0.1 m / s, the wear radius was 5 mm, and the sliding distance was 1000 m.

[0034] The hardness of the remelted coating was measured using an HV-10000A Vickers microhardness tester. The applied load was 1000 N, the holding time was 15 s, and the distance between two measurement points was three times the length of the indentation diagonal. Sixteen points were selected for each sample in a square array and the average value was calculated.

[0035] Example 1 This embodiment provides a method for preparing a wear-resistant coating for a doctor blade metal-ceramic coating, comprising the following steps: (1) Prepare the raw materials for wear-resistant coating, wherein the raw materials are TiB2 powder and Ni20Cr powder, wherein the mass percentages of TiB2 powder and Ni20Cr powder are 10% and 90% respectively, and the mass percentages of Ni and Cr in Ni20Cr powder are 80% and 20% respectively; (2) The raw materials were ball-milled with a ball-to-material ratio of 1:1; the diameters of the large, medium and small balls were 5 mm, 3 mm and 1 mm respectively; the weight ratio of the large, medium and small balls was 2:3:5; the rotation speed was 600 r / min; the single operation time was 40 min; the residence time after a single operation was 10 min; the total operation time was 8 h; after ball milling, the raw materials were dried in an oven at 80℃ for 1 h.

[0036] (3) The stainless steel substrate is treated as follows: The stainless steel substrate surface is ultrasonically cleaned with ethanol to remove oil and other impurities. After cleaning, it is placed in an oven to dry. Subsequently, the stainless steel surface to be coated was roughened by sandblasting with 24-mesh brown corundum abrasive, and the roughness of the roughened particles was controlled at 2-8μm.

[0037] (4) The spraying parameters are: current 500 A, Ar gas flow rate 35 L / min, H2 flow rate 6 L / min, powder feeding rate 30 g / min, spraying distance 100 mm, and spray gun translation speed 200 mm / s. The coating is deposited on the stainless steel substrate to obtain a composite alloy wear-resistant coating with a thickness of 200-250 μm.

[0038] (5) Place the thermal spray coating on the temperature field auxiliary heating platform, set the heating temperature to 300℃, and perform laser remelting on the coating after the temperature rises to 300℃. The laser head is 600 mm away from the coating, a 10 mm diameter nozzle is used, and argon gas with a flow rate of 6 L / min is introduced as a protective gas, with an overlap rate of 50%. After the coating is remelted, it is placed on a heating platform and slowly cooled to room temperature; The parameters for the remelting process were set as follows: power of 1000 W, scanning speed of 1200 mm / min, distance between laser head and coating of 600 mm, and overlap rate of 50%.

[0039] (6) Allow to cool naturally after preparation. The prepared coating was subjected to ball-disc friction and wear test. The test was carried out simultaneously under the same conditions. The paired ball was a 5 mm Si3N4 ball with a relative sliding speed of 0.1 m / s, a wear radius of 5 mm, and a sliding distance of 1000 m.

[0040] The results show that, under unlubricated conditions, the friction coefficient of the prepared coating is 0.35±0.05, and the wear rate is (6.46±0.09)×10⁻⁶. -6 mm 3 / (N·m).

[0041] The hardness of the remelted coating was measured using an HV-10000A Vickers microhardness tester. A load of 1000 N was applied, and the holding time was 15 s. The distance between two measurement points was three times the diagonal length of the indentation. Sixteen points were selected for each sample in a square array, and the average value was calculated. The results showed that the average hardness of the coating was 478.68 HV1.

[0042] The main morphological characteristic of TiB2 particles is their nanoscale size, with lengths ranging from 50 to 150 nm and an average particle size of approximately 110 nm. These particles are approximately 25 nm thick and exist as a uniformly dispersed dopant phase within a Ni20Cr matrix. These particles exhibit high specific surface area, with an average pore structure diameter of approximately 180 nm.

[0043] from Figure 1 As can be seen, the plasma coating has a uniform thickness, with an average thickness of 200-250 μm, and no obvious delamination phenomenon is observed. The numerous pores on the surface are due to the peeling off of unmelted particles during the spraying process.

[0044] from Figure 2It can be observed that after laser remelting, the coating thickness reaches 500-600 μm, and the density of the coating is improved. Through local heating and rapid cooling, the internal pores of the material are reduced and the microstructure is more uniform, thereby enhancing the overall mechanical strength of the coating. On the other hand, laser remelting also promotes the uniform distribution and refinement of the hard phase in the coating, allowing the originally discontinuous and aggregated hard particles to be better dispersed, further improving the wear resistance of the coating.

[0045] This invention utilizes a nanoscale TiB2-reinforced cermet wear-resistant coating and specific settings of coating parameters to achieve controllable deposition of a high-performance wear-resistant coating and regulate its microstructure and interfacial mechanical properties, thereby improving the wear condition of the friction interface.

[0046] Example 2 This embodiment provides a method for preparing a wear-resistant coating for a coated scraper cermet, which differs from Embodiment 1 in that the mass ratio of NiCr powder is 100%, no reinforcing phase is added, and all other conditions are the same as in Embodiment 1.

[0047] The prepared coating was subjected to a ball-disc friction and wear test. The test was conducted simultaneously under the same conditions as in Example 1. The paired ball was a 5 mm Si3N4 ball, the relative sliding speed was 0.1 m / s, the wear radius was 5 mm, and the sliding distance was 1000 m.

[0048] The results show that, under unlubricated conditions, the friction coefficient of the prepared coating is 0.45±0.05, and the wear rate is (12.6±0.09)×10⁻⁶. -6 mm 3 / (N·m).

[0049] The hardness of the remelted coating was measured using an HV-10000A Vickers microhardness tester. A load of 1000 N was applied, and the holding time was 15 s. The distance between two measurement points was three times the diagonal length of the indentation. Sixteen points were selected for each sample in a square array, and the average value was calculated. The results showed that the average hardness of the coating was 406.71 HV1.

[0050] Example 3 The method for preparing a wear-resistant coating for a coated scraper cermet provided in this embodiment differs from that in Example 1 in that the mass percentage of TiB2 powder is 1% and the mass percentage of NiCr powder is 99%.

[0051] The prepared coating was subjected to a ball-disc friction and wear test. The test was conducted simultaneously under the same conditions as in Example 1. The paired ball was a 5 mm Si3N4 ball, the relative sliding speed was 0.1 m / s, the wear radius was 5 mm, and the sliding distance was 1000 m.

[0052] The results show that, under unlubricated conditions, the friction coefficient of the prepared coating is 0.38 ± 0.05, and the wear rate is (10.42 ± 0.09) × 10⁻⁶. -6 mm 3 / (N·m).

[0053] The hardness of the remelted coating was measured using an HV-10000A Vickers microhardness tester. A load of 1000 N was applied, and the holding time was 15 s. The distance between two measurement points was three times the diagonal length of the indentation. Sixteen points were selected for each sample in a square array, and the average value was calculated. The results showed that the average hardness of the coating was 442.32 HV1.

[0054] Example 4 The method for preparing a wear-resistant coating for a coated scraper cermet provided in this embodiment differs from that in Example 1 in that the mass percentage of TiB2 powder is 5% and the mass percentage of NiCr powder is 95%.

[0055] The prepared coating was subjected to a ball-disc friction and wear test. The test was conducted simultaneously under the same conditions as in Example 1. The paired ball was a 5 mm Si3N4 ball, the relative sliding speed was 0.1 m / s, the wear radius was 5 mm, and the sliding distance was 1000 m.

[0056] The results show that, under unlubricated conditions, the friction coefficient of the prepared coating is 0.46±0.05, and the wear rate is (7.94±0.09)×10⁻⁶. -6 mm 3 / (N·m).

[0057] The hardness of the remelted coating was measured using an HV-10000A Vickers microhardness tester. A load of 1000 N was applied, and the holding time was 15 s. The distance between two measurement points was three times the diagonal length of the indentation. Sixteen points were selected for each sample in a square array, and the average value was calculated. The results showed that the average hardness of the coating was 464.54 HV1.

[0058] Example 5 The method for preparing a wear-resistant coating for a coated scraper cermet provided in this embodiment differs from that in Embodiment 1 in that the mass percentage of TiB2 powder is 15% and the mass percentage of NiCr powder is 85%.

[0059] The prepared coating was subjected to a ball-disc friction and wear test. The test was conducted simultaneously under the same conditions as in Example 1. The paired ball was a 5 mm Si3N4 ball, the relative sliding speed was 0.1 m / s, the wear radius was 5 mm, and the sliding distance was 1000 m.

[0060] The results show that, under unlubricated conditions, the friction coefficient of the prepared coating is 0.52±0.05, and the wear rate is (11.89±0.09)×10⁻⁶. -6 mm 3 / (N·m).

[0061] The hardness of the remelted coating was measured using an HV-10000A Vickers microhardness tester. A load of 1000 N was applied, and the holding time was 15 s. The distance between two measurement points was three times the diagonal length of the indentation. Sixteen points were selected for each sample in a square array, and the average value was calculated. The results showed that the average hardness of the coating was 438.43 HV1.

[0062] See the schematic diagram of wear rate of remelted coatings with different powder ratios. Figure 3 See the schematic diagram of Vickers hardness of remelted coatings with different powder ratios. Figure 5 .

[0063] Example 6 The method for preparing a wear-resistant coating for a coated scraper metal ceramic provided in this embodiment differs from that in embodiment 1 in that the power of the remelting process used in step (5) is set to 800 W.

[0064] The prepared coating was subjected to ball-disc friction and wear test. The test was carried out simultaneously under the same conditions as in Example 1. The paired ball was a 5 mm Si3N4 ball, the relative sliding speed was 0.1 m / s, the wear radius was 5 mm, and the sliding distance was 1000 m.

[0065] The results show that, under unlubricated conditions, the friction coefficient of the prepared coating is approximately 0.43 ± 0.05, and the wear rate is (9.56 ± 0.09) × 10⁻⁶. -6 mm 3 / (N·m).

[0066] The hardness of the remelted coating was measured using an HV-10000A Vickers microhardness tester. A load of 1000 N was applied, and the holding time was 15 s. The distance between two measurement points was three times the diagonal length of the indentation. Sixteen points were selected for each sample in a square array, and the average value was calculated. The results showed that the average hardness of the coating was 423.86 HV1.

[0067] Example 7 The method for preparing a wear-resistant coating for a coated scraper metal ceramic provided in this embodiment differs from that in embodiment 1 in that the power of the remelting process used in step (5) is set to 1200 W.

[0068] The prepared coating was subjected to ball-disc friction and wear test. The test was carried out simultaneously under the same conditions as in Example 1. The paired ball was a 5 mm Si3N4 ball, the relative sliding speed was 0.1 m / s, the wear radius was 5 mm, and the sliding distance was 1000 m.

[0069] The results show that, under unlubricated conditions, the friction coefficient of the prepared coating is 1.23±0.05, and the wear rate is (7.57±0.09)×10⁻⁶. -6 mm 3 / (N·m).

[0070] The hardness of the remelted coating was measured using an HV-10000A Vickers microhardness tester. A load of 1000 N was applied, and the holding time was 15 s. The distance between two measurement points was three times the diagonal length of the indentation. Sixteen points were selected for each sample in a square array, and the average value was calculated. The results showed that the average hardness of the coating was 445.68 HV1.

[0071] See the schematic diagram of wear rate of remelted coating under different laser powers of the present invention. Figure 4 .

[0072] Example 8 The method for preparing a wear-resistant coating for a coated scraper metal ceramic provided in this embodiment differs from that in embodiment 1 in that, in step (5), the coating is not preheated, but is placed on a heating platform and then laser remelted.

[0073] The prepared coating was subjected to a ball-disc friction and wear test. The test was conducted simultaneously under the same conditions as in Example 1. The paired ball was a 5 mm Si3N4 ball, the relative sliding speed was 0.1 m / s, the wear radius was 5 mm, and the sliding distance was 1000 m.

[0074] The results showed that the remelted coating produced numerous microcracks and exhibited severe spalling on its surface. Under unlubricated conditions, the friction coefficient of the prepared coating was 0.87±0.05, and the wear rate was (11.57±0.09)×10⁻⁶. -6 mm 3 / (N·m).

[0075] The hardness of the remelted coating was measured using an HV-10000A Vickers microhardness tester. A load of 1000 N was applied, and the holding time was 15 s. The distance between two measurement points was three times the diagonal length of the indentation. Sixteen points were selected for each sample in a square array, and the average value was calculated. The results showed that the average hardness of the coating was 402.15 HV1.

[0076] As can be clearly seen from the above embodiments, Embodiment 1 is the best implementation method. Using the present invention significantly improves the wear resistance of the coating and reduces the coefficient of friction. The coating can well meet the wear resistance requirements of coating blades for high-speed paper machines.

[0077] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing a wear-resistant coating for a doctor blade metal-ceramic coating, characterized in that: include, Ni20Cr powder and TiB2 powder were weighed and subjected to high-energy ball milling to prepare composite powder. After ball milling, the powder was dried to obtain dried NiCr-based ceramic powder. The ball milling process was carried out with a ball-to-powder ratio of 1:1; the diameters of the large, medium, and small balls were 5 mm, 3 mm, and 1 mm, respectively; the weight ratio of the large, medium, and small balls was 2:3:5; the rotation speed was 600 r / min; the single run time was 40 min; the residence time after a single run was 10 min; and the total running time was 8 h. A composite coating is formed on the substrate surface using NiCr-based ceramic powder that has been treated by atmospheric plasma spraying. The parameters of the plasma spraying are: current 500 A, Ar gas flow rate 40 L / min, H2 flow rate 5 L / min, powder feeding rate 40 g / min, spraying distance 100 mm, and spray gun translation speed 200 mm / s. Laser remelting technology is used to remelt the composite coating to form a remelted coating on the substrate surface; The remelting process includes a preheating process and a remelting process. The preheating process includes placing the coating after atmospheric plasma spraying on a temperature field-assisted heating platform, setting the heating temperature to 300°C, and then performing laser remelting on the coating. The parameters of the remelting process include: selected power of 800W, 1000W and 1200W, scanning speed of 1200 mm / min, laser head distance from coating of 600 mm, use of nozzle with diameter of 10 mm, argon gas with flow rate of 6 L / min as protective gas, overlap rate of 50%, and after coating remelting, it is placed on a heating platform to be slowly cooled to room temperature; The mass percentages of Ni20Cr powder and TiB2 powder are 85%–99% and 1%–15%, respectively; the average particle size of Ni20Cr powder is 45–85 μm, and the average particle size of TiB2 powder is 300 nm.

2. The preparation method according to claim 1, characterized in that: The surface treatment of the substrate includes, The substrate surface was ultrasonically cleaned with ethanol to remove oil stains; After cleaning, place the product in an oven to dry. Subsequently, the substrate surface to be sprayed was roughened by sandblasting with 24-mesh brown corundum abrasive, and the roughness of the roughened particles was controlled at 2~8μm.

3. The preparation method according to claim 1, characterized in that: In the Ni20Cr powder, the mass percentages of Ni and Cr are 80% and 20%, respectively.

4. The preparation method according to claim 3, characterized in that: The powder was dried for 1 hour at a temperature of 80°C.

5. The preparation method according to claim 1, characterized in that: The substrate surface treatment also includes polishing the surface-mounted sample with 600, 1200, 2000, and 3000 grit wet sandpaper respectively to make the surface roughness less than 0.5 μm.

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