An etch-resistant ceramic coating and method of making the same

Abstract

The present application relates to the technical field of ceramic coating preparation, and discloses an etching-resistant ceramic coating and a preparation method thereof. The method comprises the following steps: preparing a multicomponent composite ceramic powder based on yttrium oxide and yttrium fluoride and containing zirconium oxide and aluminum oxide according to phase equilibrium design; performing spray granulation treatment on the powder to obtain spherical feed powder with good fluidity; and preparing the feed powder into a coating by using a plasma spraying process. In the spray granulation step, the ceramic powder is mixed with deionized water, a dispersant and a binder to form a slurry, and the required powder is obtained through centrifugal spray drying and heat treatment. The spraying can be performed by using a supersonic atmospheric plasma spraying process or a suspension plasma spraying process. The present application stabilizes the phase composition of the coating material through phase equilibrium design, and obtains an etching-resistant ceramic coating which is phase-stable, dense and has high bonding strength by combining optimized granulation and spraying processes, and the coating is suitable for protection of semiconductor processing equipment.

Description

Technical Field

[0001] This invention relates to the field of ceramic coating preparation technology, specifically to an etch-resistant ceramic coating and its preparation method. Background Technology

[0002] In manufacturing processes such as dry etching and chemical vapor deposition for semiconductors and display panels, components within the process chamber need to be exposed to a highly reactive plasma environment for extended periods, placing extremely high demands on the performance of etching-resistant ceramic coatings. Existing technologies focus on improving the etching resistance, bonding strength, and lifespan of coatings through material composition design and advanced fabrication processes. Chinese Patent Publication No. CN120041775A discloses a method for preparing an etching-resistant ceramic coating material. This method introduces multiple rare earth elements and yttrium oxide to form an entropy-stabilized material, optimizing the crystal phase structure, and combines this with improved spray granulation and suspension plasma spraying techniques to prepare the coating. While such high-entropy or entropy-stabilized designs contribute to performance improvement, their material systems are typically complex, raw material costs are high, and controlling the long-term thermodynamic phase stability of multiple components presents challenges. Chinese Patent Publication No. CN121555941A proposes a long-life suspension plasma spraying thermal barrier coating based on a platinum-aluminum coating and its preparation method. This method focuses on preparing a ceramic layer with a vertical crack structure on a specially treated adhesive layer to improve thermal cycling life. Its focus is more on the thermal shock resistance of thermal barrier coatings, and the raw material used is a specific fully stabilized zirconia powder. However, the material system may have limitations in its specificity and adaptability to the protection requirements against specific etching gases in complex chemical environments. Therefore, it is currently necessary to find a method to prepare coatings with excellent etching resistance, high bonding strength, and good process stability, starting from the material design stage, through more controllable phase composition design and stabilization, and combined with an efficient and reliable process chain. Summary of the Invention

[0003] The purpose of this invention is to provide an etch-resistant ceramic coating and its preparation method to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides an etch-resistant ceramic coating and a method for preparing the same, the method comprising: Step S1: Prepare multi-component composite ceramic powder based on phase equilibrium design; Step S2: Spray granulation treatment is performed on the multi-component composite ceramic powder prepared in step S1. Step S3: The powder obtained in step S2 is used to prepare a coating by plasma spraying.

[0005] Preferably, step S1 specifically includes: selecting yttrium oxide and yttrium fluoride powders with a purity of not less than 99.999% as basic raw materials, and weighing and mixing them according to a molar ratio of 1:(0.2-0.5); adding zirconium oxide (3-8 wt% of total mass) and alumina (1-3 wt% of total mass) as phase stabilizers and sintering aids to the mixed powder; placing all the powder in a planetary ball mill, using ethanol as the dispersion medium, zirconium oxide balls as grinding balls, a ball-to-material ratio of 5:1, and a rotation speed of 300 rpm, and performing wet ball milling for 12-24 hours; after ball milling, drying the slurry at 80°C, and then calcining it at 1200-1400°C for 2-4 hours under an argon atmosphere, followed by crushing and passing it through a 400-mesh sieve to obtain the multi-component composite ceramic powder.

[0006] Preferably, step S2 specifically includes: mixing the multi-component composite ceramic powder obtained in step S1 with deionized water, dispersant, and binder at a mass ratio of 100:(40-60):(0.5-1.5):(3-8) to prepare a slurry with a solid content of 50-65wt%; the dispersant is ammonium polyacrylate, and the binder is polyvinyl alcohol; feeding the slurry into a centrifugal spray drying tower, controlling the inlet temperature at 180-220℃, the outlet temperature at 90-110℃, the atomizing disc rotation speed at 10000-15000 rpm, and the feed rate at 10-20 mL / min; collecting the obtained spherical powder, and heat-treating it at 500-600℃ for 1-2 hours to remove organic components, finally obtaining ceramic feed powder with a particle size distribution D50 of 20-25μm and a flowability of less than 35 s / 50g.

[0007] Preferably, step S3 is a supersonic atmospheric plasma spraying process, specifically including: feeding the ceramic feed powder obtained in step S2 into a 9M powder feeder, using argon as the main gas with a flow rate of 40-50 slpm and hydrogen as the secondary gas with a flow rate of 10-15 slpm; setting the spraying power to 40-50 kW, the spraying distance to 100-120 mm, the spray gun moving speed to 800-1000 mm / s, and controlling the single-pass thickness to 10-20 μm; preheating the substrate to 300-400℃ before starting spraying until the coating thickness reaches 200-500 μm.

[0008] Preferably, between step S1 and step S2, a nano-suspension preparation step is also included: taking the calcined but unsieved multi-component composite ceramic powder block from step S1, and performing secondary grinding using a high-energy nano-sand mill, with 0.3 mm diameter zirconia beads as the grinding medium, grinding for 6-10 hours to obtain a nano-ceramic slurry with an average particle size D50 of 80-150 nm; adding 2% by mass of polycarboxylate dispersant to the slurry, adjusting the pH value to 9-10, and after ultrasonic dispersion and vacuum defoaming, obtaining a nano-ceramic suspension with a solid content of 25-35 wt%.

[0009] Preferably, step S3 is a suspension plasma spraying process, specifically including: placing the nano-ceramic suspension prepared in claim 5 in a magnetically stirred storage tank, and using a screw pump to deliver it to a two-stage atomizing nozzle at a rate of 20-30 mL / min; the atomizing gas is nitrogen, with a pressure of 0.3-0.5 MPa; using an F4-MB type plasma spray gun, with a mixture of argon and hydrogen as the working gas, a current of 500-600 A, and a voltage of 50-60 V; the spraying distance is 60-80 mm, the spray gun scanning speed is 300-500 mm / s, and depositing a coating on a substrate preheated to 400-500℃.

[0010] Preferably, before plasma spraying in step S3, the metal or ceramic substrate is pretreated, including: roughening the substrate surface by sandblasting with brown corundum abrasive with a particle size of 24 mesh to achieve a surface roughness Ra of 4-6 μm; ultrasonic cleaning with anhydrous ethanol after sandblasting; and spraying immediately after drying.

[0011] Preferably, after sandblasting and cleaning, a bonding underlayer is first sprayed onto the pretreated substrate surface; the bonding underlayer material is NiCrAlY alloy powder with a particle size of -140 to +325 mesh; an atmospheric plasma spraying process is used to prepare a bonding underlayer with a thickness of 50-80 μm under the conditions of argon flow rate of 40 slpm, hydrogen flow rate of 10 slpm, power of 30 kW, and spraying distance of 120 mm.

[0012] Preferably, in the plasma spraying process of step S3, an in-situ laser remelting assisted process is introduced: a continuous fiber laser with a wavelength of 1064 nm, a laser power of 300-500 W, a spot diameter of 2 mm is used, and the laser beam is synchronously irradiated on the surface of the newly deposited coating at an angle of 30-45 degrees to the plasma flame. The laser scanning speed is synchronized with the spray gun moving speed.

[0013] Preferably, the present invention further includes an etch-resistant ceramic coating, which is prepared by the above-described method for preparing an etch-resistant ceramic coating.

[0014] Compared with the prior art, the beneficial effects of the present invention are: In this scheme, the material composition is designed based on the principle of phase equilibrium, selecting a specific molar ratio of yttrium oxide and yttrium fluoride as the base, and introducing a precise ratio of zirconium oxide and alumina as phase stabilizers and sintering aids. By controlling the ratio of the basic components and the content of additives, the target crystal phase is pre-regulated and stabilized during the material synthesis stage, effectively suppressing the formation of unfavorable impurity phases or brittle phases during subsequent high-temperature spraying and service. This composition design guided by thermodynamic phase diagrams results in ceramic powders with a clear and stable distribution of primary and secondary phases. The coating prepared in this way has a more thermodynamically stable phase composition and is less prone to phase transitions that lead to performance degradation when facing high temperatures and active plasma erosion. The etching resistance of the coating is enhanced from the material itself, exhibiting more consistent performance and a longer service life in harsh etching environments.

[0015] This scheme constructs a complete process chain from powder synthesis and precursor treatment to coating deposition. First, a multi-component composite ceramic powder with a stable phase composition is prepared through phase equilibrium design, providing a reliable material basis for the coating. Subsequently, the powder is processed using an optimized spray granulation process. By precisely controlling the slurry formulation and drying parameters, a feed powder with good sphericity, excellent flowability, and concentrated particle size distribution is obtained, ensuring the uniformity and stability of powder feeding during subsequent spraying. Finally, a parameter-matched plasma spraying process is employed, effectively transferring the characteristics of the powder material to the coating structure, whether using granulated micron-sized powder or further processed nano-suspensions. The interconnected and coordinated process parameters of the three stages improve the deposition efficiency of the coating, reduce internal structural defects, and achieve a denser interlayer bond. The entire process route is clear and controllable, reducing inconsistencies in coating quality caused by raw material fluctuations or process parameter mismatches. The resulting coating exhibits high bonding strength and low porosity, achieving simultaneous improvement in performance and reliability. Attached Figure Description

[0016] Figure 1 This diagram illustrates the operational steps of a method for preparing an etch-resistant ceramic coating according to the present invention. Detailed Implementation

[0017] See appendix Figure 1 The present invention will be further described in detail below with reference to specific embodiments and comparative examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0018] The core of the method for preparing the etch-resistant ceramic coating described in this invention lies in the preparation of multi-component composite ceramic powder through phase balance design, combined with spray granulation or nano-suspension preparation processes, and further aided by plasma spraying and optional in-situ laser remelting processes, to obtain a dense, firmly bonded ceramic coating with excellent etch resistance. In the following examples and comparative examples, unless otherwise specified, all raw materials are commercially available conventional products, all equipment is industry-standard equipment, and all testing methods adopt national standards or industry-standard testing methods.

[0019] Test method description: Coating density test: The Archimedes water displacement method in GB / T 39688-2020 "Test Method for Density of Ceramic Coatings" was adopted. Each sample was tested 3 times and the average value was taken. Density = (Measured density / Theoretical density) × 100%. The theoretical density is calculated based on the mass fraction and density of each component of the multi-component composite ceramic powder. Coating bond strength test: GB / T 8642-2002 "Determination of bond strength of thermal spray coatings" was adopted. The tensile method was used. Each sample was tested 3 times and the average value was taken. The unit is MPa. Etching resistance test: Plasma etching test was adopted to simulate the industrial plasma etching environment. The etching gas was a CF4 / Ar / O2 mixed gas (volume ratio of 2:7:1), the etching power was 300W, and the etching time was 120min. The mass loss of the coating before and after etching was measured, and the etching rate (nm / min) was calculated. The lower the etching rate, the better the etching resistance. At the same time, the surface morphology of the coating after etching was observed to evaluate the etching resistance stability of the coating. Coating microhardness test: A Vickers hardness tester was used with a load of 300g and a holding time of 15s. Five different points were tested on each sample, and the average value was taken. The unit is HV. Powder flowability test: The flow time of 50g of ceramic feed powder was tested using a Hall effect flow meter. The unit is s / 50g. The shorter the flow time, the better the flowability. Powder and coating particle size testing: A laser particle size analyzer was used to test the particle size distribution D50 of powder and nano-ceramic slurry, with units of μm or nm; Surface roughness test: The surface roughness Ra of the substrate after pretreatment and the coating surface was tested using a surface roughness meter, and the unit is μm.

[0020] Example 1: This embodiment employs a supersonic atmospheric plasma spraying process, combined with an in-situ laser remelting assisted process, to prepare an etch-resistant ceramic coating. The specific steps are as follows: Step 1: Matrix Pretreatment 45# steel was selected as the substrate, with dimensions of 100mm×100mm×10mm. First, the substrate surface was roughened by sandblasting with 24-mesh brown corundum abrasive. The sandblasting pressure was 0.6MPa, the sandblasting angle was 45°, and the sandblasting time was 10min, so that the surface roughness Ra of the substrate reached 5μm. After sandblasting, the substrate was placed in anhydrous ethanol and ultrasonically cleaned with an ultrasonic cleaner at a power of 300W for 15min to remove surface oil and impurities. After removal, it was placed in a 100℃ oven to dry for 20min. Immediately after drying, the bonding primer was sprayed.

[0021] Step 2: Preparation of the bonding substrate NiCrAlY alloy powder was selected as the bonding underlayer material. The powder had a particle size of -140 to +325 mesh and a purity of not less than 99.5%. The bonding underlayer was prepared by atmospheric plasma spraying. The spraying equipment was a plasma spraying machine with an argon flow rate of 40 slpm, a hydrogen flow rate of 10 slpm, a spraying power of 30kW, a spraying distance of 120mm, a spray gun moving speed of 600mm / s, and a single pass thickness of 5μm. The bonding underlayer thickness reached 65μm after spraying. After spraying, the material was allowed to cool naturally to room temperature.

[0022] Step 3: Preparation of multi-component composite ceramic powder Based on phase equilibrium design, yttrium oxide (Y₂O₃) powder and yttrium fluoride (YF₃) powder with a purity of 99.999% were selected as basic raw materials and weighed and mixed at a molar ratio of 1:0.35, with 100g of yttrium oxide powder and 42.3g of yttrium fluoride powder weighed. Zirconia (ZrO₂) powder (5wt%) and alumina (Al₂O₃) powder (2wt%) were added to the above mixed powder as phase stabilizers and sintering aids, with 7.1g of zirconium oxide powder and 2.8g of alumina powder added. All powders were placed in a planetary ball mill, using anhydrous ethanol as the dispersion medium, and the dispersion medium was... The mass of the powder used was 1.5 times the total mass of the powder. Zirconia balls were used as grinding balls with a ball-to-powder ratio of 5:1. The ball mill speed was set to 300 rpm, and wet ball milling was carried out for 18 hours. After ball milling, the resulting slurry was poured into a tray and placed in an 80℃ forced-air drying oven for 12 hours to remove the ethanol medium. The dried powder blocks were placed in a tube furnace and calcined at 1300℃ for 3 hours under an argon atmosphere. The calcination heating rate was 5℃ / min, and the cooling rate was 3℃ / min. After calcination, the powder blocks were taken out, crushed by a jaw crusher, and then screened through a 400-mesh standard sieve to remove coarse particles, thus obtaining multi-element composite ceramic powder.

[0023] Step 4: Spray granulation treatment The multi-component composite ceramic powder obtained in step 3 was mixed with deionized water, dispersant ammonium polyacrylate, and binder polyvinyl alcohol in a mass ratio of 100:50:1.0:5.5. The mixture was placed in a high-speed stirrer at a stirring speed of 800 rpm for 60 min to prepare a uniform slurry with a solid content of 58 wt%. The slurry was then fed into a centrifugal spray drying tower with an inlet temperature of 200℃, an outlet temperature of 100℃, an atomizing disc speed of 12000 rpm, and a feed rate of 15 mL / min. After atomization and drying, spherical powder was collected. The spherical powder was placed in a muffle furnace and heat-treated at 550℃ for 1.5 hours in air to remove the organic dispersant and binder from the powder, finally obtaining ceramic feed powder with a particle size distribution D50 of 22 μm and a flowability of 32 s / 50 g.

[0024] Step 5: Supersonic atmospheric plasma spraying and in-situ laser remelting The ceramic feed powder obtained in step 4 was fed into a 9M powder feeder, and a coating was prepared using supersonic atmospheric plasma spraying. The spraying parameters were set as follows: argon as the main gas with a flow rate of 45 slpm, hydrogen as the secondary gas with a flow rate of 12 slpm, spraying power of 45kW, spraying distance of 110mm, spray gun moving speed of 900mm / s, and single-pass thickness controlled at 15μm. The pretreated substrate with the prepared bonding underlayer was preheated to 350℃, and spraying began after the preheating temperature was stabilized. An in-situ laser remelting assisted process was introduced during the spraying process, using a continuous fiber laser with a wavelength of 1064nm, a laser power of 400W, and a spot diameter of 2mm. The laser beam was synchronously irradiated on the newly deposited coating surface at an angle of 38 degrees to the plasma flow, and the laser scanning speed was synchronized with the spray gun moving speed. Spraying continued until the total coating thickness reached 350μm. After spraying, the coating was naturally cooled to room temperature to obtain an etch-resistant ceramic coating.

[0025] Example 2: This embodiment employs a suspension plasma spraying process, combined with an in-situ laser remelting assisted process, to prepare an etch-resistant ceramic coating. The specific steps are as follows: Step 1: Matrix Pretreatment Stainless steel (316L) was selected as the substrate, with dimensions of 100mm×100mm×10mm. First, the substrate surface was roughened by sandblasting with 24-mesh brown corundum abrasive. The sandblasting pressure was 0.7MPa, the sandblasting angle was 50°, and the sandblasting time was 12min, so that the surface roughness Ra of the substrate reached 4.5μm. After sandblasting, the substrate was placed in anhydrous ethanol and ultrasonically cleaned with an ultrasonic cleaner with an ultrasonic power of 350W for 12min to remove surface oil and impurities. After removal, it was placed in a 110℃ oven to dry for 15min. Immediately after drying, the bonding primer was sprayed.

[0026] Step 2: Preparation of the bonding substrate NiCrAlY alloy powder was selected as the bonding underlayer material. The powder had a particle size of -140 to +325 mesh and a purity of not less than 99.5%. The bonding underlayer was prepared by atmospheric plasma spraying. The argon flow rate was set to 40 slpm, the hydrogen flow rate to 10 slpm, the spraying power to 30kW, the spraying distance to 120mm, the spray gun moving speed to 550mm / s, and the thickness of a single pass to 4μm. The bonding underlayer thickness reached 55μm after spraying. After spraying, the material was allowed to cool naturally to room temperature.

[0027] Step 3: Preparation of multi-component composite ceramic powder Based on phase equilibrium design, yttrium oxide (Y₂O₃) powder and yttrium fluoride (YF₃) powder with a purity of 99.999% were selected as basic raw materials and weighed and mixed at a molar ratio of 1:0.25, with 100g of yttrium oxide powder and 30.2g of yttrium fluoride powder weighed. Zirconia (ZrO₂) powder (3wt% of total mass) and alumina (Al₂O₃) powder (1.5wt% of total mass) were added to the above mixed powder as phase stabilizers and sintering aids, with 4.0g of zirconium oxide powder and 2.0g of alumina powder added. All powders were placed in a planetary ball mill and... Anhydrous ethanol was used as the dispersion medium, with the amount of dispersion medium being 1.2 times the total mass of the powder. Zirconia balls were used as grinding balls, with a ball-to-powder ratio of 5:1. The ball mill speed was set to 300 rpm, and wet ball milling was performed for 12 hours. After ball milling, the resulting slurry was poured into a tray and placed in an 80℃ forced-air drying oven for 10 hours to remove the ethanol medium. The dried powder blocks were placed in a tube furnace and calcined at 1200℃ for 4 hours under an argon atmosphere, with a calcination heating rate of 4℃ / min and a cooling rate of 2℃ / min. After calcination, calcined but unsieved multi-component composite ceramic powder blocks were obtained for later use.

[0028] Step 4: Preparation of Nano-Suspension Take 100g of the calcined but unsieved multi-component ceramic powder block from step 3 and place it in a high-energy nano-sand mill. Use zirconia beads with a diameter of 0.3mm as the grinding medium. The amount of grinding medium is 8 times the mass of the powder block. Set the mill speed to 2000rpm and perform secondary grinding for 8 hours to obtain a nano-ceramic slurry with an average particle size D50 of 110nm. Add 2% by mass of polycarboxylate dispersant (based on the total mass of the slurry) to the nano-ceramic slurry and stir evenly. Adjust the pH value of the slurry to 9.5 with ammonia water. Then put the slurry into an ultrasonic disperser with an ultrasonic power of 400W and an ultrasonic time of 30min. Then perform vacuum defoaming treatment with a vacuum degree of -0.09MPa and a defoaming time of 20min to finally obtain a nano-ceramic suspension with a solid content of 30wt%.

[0029] Step 5: Suspension plasma spraying and in-situ laser remelting The nano-ceramic suspension obtained in step 4 was placed in a storage tank equipped with a magnetic stirrer at a stirring speed of 300 rpm to maintain uniform dispersion. A screw pump was used to deliver the suspension to a two-stage atomizing nozzle at a rate of 25 mL / min. Nitrogen was used as the atomizing gas, and the atomization pressure was set to 0.4 MPa. An F4-MB plasma spray gun was used, employing a mixture of argon and hydrogen as the working gas, with an argon flow rate of 42 slpm and a hydrogen flow rate of 13 slpm. The spraying current was set to 550 A, the voltage to 55 V, the spraying distance to 70 mm, and the spray gun scanning speed to [missing information]. The speed is 400 mm / s; the pretreated and prepared bonding substrate is preheated to 450°C, and spraying begins after the preheating temperature is stabilized. In-situ laser remelting is introduced during the spraying process. A continuous fiber laser with a wavelength of 1064 nm and a laser power of 350 W is used. The spot diameter is 2 mm. The laser beam is synchronously irradiated on the newly deposited coating surface at a 35-degree angle with the plasma flow. The laser scanning speed is synchronized with the spray gun movement speed. Spraying continues until the total coating thickness reaches 300 μm. After spraying, the coating is naturally cooled to room temperature to obtain an etch-resistant ceramic coating.

[0030] Example 3: This embodiment employs a supersonic atmospheric plasma spraying process, without introducing an in-situ laser remelting assisted process, to prepare an etch-resistant ceramic coating. The specific steps are as follows: Step 1: Matrix Pretreatment Titanium alloy (TC4) was selected as the substrate, with dimensions of 100mm×100mm×10mm. First, the substrate surface was roughened by sandblasting with 24-mesh brown corundum abrasive. The sandblasting pressure was 0.5MPa, the sandblasting angle was 40°, and the sandblasting time was 8min, so that the surface roughness Ra of the substrate reached 5.5μm. After sandblasting, the substrate was placed in anhydrous ethanol and ultrasonically cleaned with an ultrasonic cleaner with an ultrasonic power of 250W for 18min to remove surface oil and impurities. After removal, it was placed in a 90℃ oven to dry for 25min. Immediately after drying, the bonding primer was sprayed.

[0031] Step 2: Preparation of the bonding substrate NiCrAlY alloy powder was selected as the bonding underlayer material. The powder had a particle size of -140 to +325 mesh and a purity of not less than 99.5%. The bonding underlayer was prepared by atmospheric plasma spraying. The argon flow rate was set to 40 slpm, the hydrogen flow rate to 10 slpm, the spraying power to 30kW, the spraying distance to 120mm, the spray gun moving speed to 650mm / s, and the thickness of a single pass to 6μm. The thickness of the bonding underlayer reached 75μm after spraying. After spraying, the material was allowed to cool naturally to room temperature.

[0032] Step 3: Preparation of multi-component composite ceramic powder Based on phase equilibrium design, yttrium oxide (Y₂O₃) powder and yttrium fluoride (YF₃) powder with a purity of 99.999% were selected as basic raw materials and weighed and mixed at a molar ratio of 1:0.45, with 100g of yttrium oxide powder and 54.4g of yttrium fluoride powder weighed. Zirconia (ZrO₂) powder (7wt%) and alumina (Al₂O₃) powder (2.5wt%) were added to the above mixed powder as phase stabilizers and sintering aids, with 11.0g of zirconium oxide powder and 4.0g of alumina powder added. All powders were placed in a planetary ball mill and dispersed using anhydrous ethanol as the dispersion medium. The amount of grinding media was 1.8 times the total mass of the powder. Zirconia balls were used as grinding balls with a ball-to-material ratio of 5:1. The ball mill speed was set to 300 rpm, and wet ball milling was performed for 24 hours. After ball milling, the resulting slurry was poured into a tray and placed in an 80℃ forced-air drying oven for 14 hours to remove the ethanol media. The dried powder blocks were placed in a tube furnace and calcined at 1400℃ for 2 hours under an argon atmosphere. The calcination heating rate was 6℃ / min, and the cooling rate was 4℃ / min. After calcination, the powder blocks were removed, crushed using a jaw crusher, and then screened through a 400-mesh standard sieve to remove coarse particles, obtaining multi-element composite ceramic powder.

[0033] Step 4: Spray granulation treatment The multi-component composite ceramic powder obtained in step 3 was mixed with deionized water, dispersant ammonium polyacrylate, and binder polyvinyl alcohol in a mass ratio of 100:55:1.3:7.0. The mixture was placed in a high-speed stirrer at a stirring speed of 900 rpm for 70 min to prepare a uniform slurry with a solid content of 62 wt%. The slurry was then fed into a centrifugal spray drying tower with an inlet temperature of 210℃, an outlet temperature of 105℃, an atomizing disc speed of 14000 rpm, and a feed rate of 18 mL / min. After atomization and drying, spherical powder was collected. The spherical powder was then placed in a muffle furnace and heat-treated at 580℃ for 1.2 hours in air to remove the organic dispersant and binder from the powder, ultimately obtaining ceramic feed powder with a particle size distribution D50 of 24 μm and a flowability of 30 s / 50 g.

[0034] Step 5: Supersonic atmospheric plasma spraying The ceramic feed powder obtained in step 4 was fed into a 9M powder feeder, and a coating was prepared using supersonic atmospheric plasma spraying. The spraying parameters were set as follows: argon as the main gas with a flow rate of 48 slpm, hydrogen as the secondary gas with a flow rate of 14 slpm, spraying power of 48kW, spraying distance of 115mm, spray gun moving speed of 950mm / s, and single-pass thickness controlled at 18μm. The pretreated substrate with the prepared bonding underlayer was preheated to 380℃, and spraying began after the preheating temperature was stabilized, without introducing in-situ laser remelting assisted process. Spraying continued until the total coating thickness reached 450μm. After spraying, the substrate was naturally cooled to room temperature to obtain an etch-resistant ceramic coating.

[0035] Comparative Example 1: This comparative example did not add any phase stabilizers or sintering aids, and all other process parameters were exactly the same as in Example 1. The specific steps are as follows: Step 1: Matrix Pretreatment The process is exactly the same as step 1 in Example 1, that is, 45 steel is selected as the substrate with a size of 100mm×100mm×10mm, sandblasted to roughen to Ra=5μm, ultrasonically cleaned and dried, and the bonding underlayer is sprayed immediately.

[0036] Step 2: Preparation of the bonding substrate The process is exactly the same as step 2 in Example 1, that is, using NiCrAlY alloy powder and atmospheric plasma spraying to prepare a bonding underlayer with a thickness of 65μm.

[0037] Step 3: Preparation of multi-component composite ceramic powder Yttrium oxide (Y₂O₃) powder and yttrium fluoride (YF₃) powder with a purity of 99.999% were selected as the base raw materials and weighed and mixed at a molar ratio of 1:0.35, with 100g of yttrium oxide powder and 42.3g of yttrium fluoride powder weighed. Zirconia and alumina powders were not added. The mixed powder was placed in a planetary ball mill, using anhydrous ethanol as the dispersion medium, with the amount of dispersion medium being 1.5 times the total mass of the powder. Zirconia balls were used as grinding balls, with a ball-to-powder ratio of 5:1, and the ball mill speed was set to 3 rpm. Wet ball milling was performed at 00 rpm for 18 hours. After ball milling, the resulting slurry was poured into a tray and dried in an 80℃ forced-air drying oven for 12 hours to remove the ethanol medium. The dried powder block was placed in a tube furnace and calcined at 1300℃ for 3 hours under an argon atmosphere, with a calcination heating rate of 5℃ / min and a cooling rate of 3℃ / min. After calcination, the powder block was taken out, crushed by a jaw crusher, and then screened through a 400-mesh standard sieve to remove coarse particles, obtaining multi-component composite ceramic powder.

[0038] Step 4: Spray granulation treatment The process is exactly the same as step 4 in Example 1, that is, mixing powder, deionized water, ammonium polyacrylate and polyvinyl alcohol in a mass ratio of 100:50:1.0:5.5 to prepare a slurry with a solid content of 58wt%, spray drying and heat treatment to obtain ceramic feed powder with a particle size D50=22μm and a flowability of 32s / 50g.

[0039] Step 5: Supersonic atmospheric plasma spraying and in-situ laser remelting The process is exactly the same as step 5 in Example 1, that is, using supersonic atmospheric plasma spraying, introducing an in-situ laser remelting assisted process, spraying to a coating thickness of 350μm, and naturally cooling to room temperature to obtain a ceramic coating.

[0040] Comparative Example 2: This comparative example does not undergo spray granulation treatment; instead, it directly uses multi-component composite ceramic powder for plasma spraying. All other process parameters are identical to those in Example 1. The specific steps are as follows: Step 1: Matrix Pretreatment The process is exactly the same as step 1 in Example 1, that is, 45 steel is selected as the substrate with a size of 100mm×100mm×10mm, sandblasted to roughen to Ra=5μm, ultrasonically cleaned and dried, and the bonding underlayer is sprayed immediately.

[0041] Step 2: Preparation of the bonding substrate The process is exactly the same as step 2 in Example 1, that is, using NiCrAlY alloy powder and atmospheric plasma spraying to prepare a bonding underlayer with a thickness of 65μm.

[0042] Step 3: Preparation of multi-component composite ceramic powder The process is exactly the same as step 3 in Example 1, namely, preparing multi-component composite ceramic powder with added zirconium oxide and alumina, and then passing it through a 400-mesh sieve for later use.

[0043] Step 4: Supersonic atmospheric plasma spraying and in-situ laser remelting The multi-component composite ceramic powder obtained in step 3 (without spray granulation) was directly fed into a 9M powder feeder, and a coating was prepared using a supersonic atmospheric plasma spraying process. The spraying parameters were exactly the same as those in step 5 of Example 1, namely, argon flow rate 45 slpm, hydrogen flow rate 12 slpm, spraying power 45kW, spraying distance 110mm, spray gun moving speed 900mm / s, and single-pass thickness 15μm. An in-situ laser remelting assisted process was introduced, the substrate was preheated to 350℃, sprayed to a coating thickness of 350μm, and naturally cooled to room temperature to obtain a ceramic coating.

[0044] Comparative Example 3: This comparative example does not involve substrate pretreatment or bonding underlayer preparation. Plasma spraying is performed directly on the original substrate surface. All other process parameters are exactly the same as in Example 1. The specific steps are as follows: Step 1: Preparation of multi-component composite ceramic powder The process is exactly the same as step 3 in Example 1, namely, preparing multi-component composite ceramic powder with added zirconium oxide and alumina, and then passing it through a 400-mesh sieve for later use.

[0045] Step 2: Spray granulation treatment The process is exactly the same as step 4 in Example 1, that is, mixing powder, deionized water, ammonium polyacrylate and polyvinyl alcohol in a mass ratio of 100:50:1.0:5.5 to prepare a slurry with a solid content of 58wt%, spray drying and heat treatment to obtain ceramic feed powder with a particle size D50=22μm and a flowability of 32s / 50g.

[0046] Step 3: Supersonic atmospheric plasma spraying and in-situ laser remelting 45 steel was selected as the substrate, with dimensions of 100mm×100mm×10mm. Without sandblasting, ultrasonic cleaning, or bonding underlayer preparation, the substrate was directly preheated to 350℃. The ceramic feed powder obtained in step 2 was fed into a 9M powder feeder, and a coating was prepared using a supersonic atmospheric plasma spraying process. The spraying parameters were exactly the same as in step 5 of Example 1. An in-situ laser remelting assisted process was introduced, and the coating was sprayed to a thickness of 350μm. The coating was then naturally cooled to room temperature to obtain the ceramic coating.

[0047] The ceramic coatings prepared in the above three examples and three comparative examples were tested for density, bonding strength, microhardness and etching resistance. At the same time, the performance of ceramic feed powder or nano suspension in Examples 1, 2, 3 and Comparative Examples 1 and 2 was tested. The test results are shown in Tables 1, 2 and 3, respectively.

[0048] Table 1: Test Results of Basic Performance of Ceramic Coatings in Examples and Comparative Examples

[0049] As shown in Table 1, the ceramic coatings prepared in the three examples are significantly better than those in the three comparative examples in terms of density, bonding strength, microhardness and etching resistance, which fully demonstrates the superiority of the preparation method of the present invention.

[0050] The coating densities of Examples 1, 2, and 3 were 98.2%, 97.8%, and 95.5%, respectively, all higher than 95%, indicating low internal porosity and dense structure. Examples 1 and 2, due to the introduction of in-situ laser remelting, utilized the high energy of the laser beam to rapidly melt and resolidify the freshly deposited coating surface, filling the micropores and defects within the coating and significantly improving its density. Example 3, without in-situ laser remelting, had a slightly lower coating density, but it remained at a high level. This was attributed to the good flowability and sphericity of the ceramic feed powder after spray granulation, resulting in uniform powder melting and dense deposition during spraying. The coating density of Comparative Examples 1, 2, and 3 was all below 93%. Comparative Example 1 did not add zirconium oxide and alumina as phase stabilizers and sintering aids. The multi-component composite ceramic powder was prone to grain growth, oxidation, and cracking during calcination and spraying, resulting in increased porosity in the coating and a density of only 90.3%. Comparative Example 2 did not undergo spray granulation treatment. The multi-component composite ceramic powder had poor flowability and uneven particle size distribution. During spraying, the powder was not fully melted and the powder was loosely packed, resulting in a density of 92.1%. Comparative Example 3 did not undergo substrate pretreatment and bonding underlayer preparation. The coating and substrate were not tightly bonded, and there were many interfacial pores, resulting in a density of 91.5%.

[0051] The coating bonding strengths of Examples 1, 2, and 3 were 68.5 MPa, 72.3 MPa, and 62.1 MPa, respectively, all higher than 60 MPa, indicating a strong bond between the coating and the substrate (or bonding underlayer). Example 2 employed a suspension plasma spraying process. The nanoparticles in the nano-ceramic suspension had a larger specific surface area and higher activity. During the spraying process, the nanoparticles could fully melt and form a good metallurgical bond with the bonding underlayer, resulting in the highest bonding strength. Example 1 introduced an in-situ laser remelting assisted process. Laser remelting can promote element diffusion between the coating and the bonding underlayer, enhancing the interfacial bonding force, resulting in a slightly lower bonding strength. Example 3 did not introduce an in-situ laser remelting assisted process, resulting in a slightly lower bonding strength, but still meeting the requirements of practical applications. The bonding strength of Comparative Examples 1, 2, and 3 was all below 55 MPa. Among them, Comparative Example 3 did not undergo substrate pretreatment or bonding underlayer preparation, and the bonding between the coating and the original substrate surface mainly relied on mechanical bonding, resulting in weak bonding force and a bonding strength of only 32.6 MPa, which was far lower than that of the Example. Comparative Example 1 did not add phase stabilizers and sintering aids, resulting in many defects inside the coating and insufficient interfacial bonding force, with a bonding strength of 45.8 MPa. Comparative Example 2 did not undergo spray granulation treatment, resulting in poor powder flowability, uneven coating accumulation during spraying, and weak interfacial bonding, with a bonding strength of 50.2 MPa.

[0052] The microhardness of the coatings in Examples 1, 2, and 3 were 1280 HV, 1320 HV, and 1150 HV, respectively, all higher than 1100 HV, indicating that the coatings have high hardness and can effectively resist the physical impact during the etching process. Example 2 used nano-suspension plasma spraying, and the refinement effect of nanoparticles significantly improved the hardness of the coating, thus resulting in the highest microhardness. Example 1 introduced an in-situ laser remelting assisted process, which refined the coating grains and made the structure denser, resulting in the second highest hardness. Example 3 did not introduce an in-situ laser remelting assisted process, and its hardness was slightly lower, but still much higher than the comparative example. The microhardness of Comparative Examples 1, 2, and 3 was all below 1050 HV. Among them, Comparative Example 1 did not add phase stabilizers and sintering aids, and the coating had large grains and a loose structure, with a hardness of only 920 HV. Comparative Example 2 did not undergo spray granulation treatment, and the coating had many internal pores and an uneven structure, with a hardness of 1010 HV. Comparative Example 3 did not undergo substrate pretreatment and bonding underlayer preparation, and the coating was not tightly bonded to the substrate, with a hardness of 1050 HV.

[0053] The etching rates of the coatings in Examples 1, 2, and 3 were 10.8 nm / min, 9.6 nm / min, and 14.2 nm / min, respectively, all below 15 nm / min, indicating that the coatings have excellent etching resistance. Example 2 used a suspension plasma spraying process, resulting in a dense and uniform nano-coating structure that effectively blocked the penetration of etching gases. Simultaneously, the high activity of the nanoparticles enabled the formation of a stable oxide film, thus resulting in the lowest etching rate. Example 1 incorporated an in-situ laser remelting assisted process, resulting in a high coating density and few defects, making it difficult for etching gases to penetrate the coating interior, thus achieving a slightly lower etching rate. Example 3 did not incorporate an in-situ laser remelting assisted process, resulting in a small number of pores within the coating, allowing for easy penetration of etching gases, leading to a slightly higher etching rate, but still far lower than the comparative example. The etching rates of Comparative Examples 1, 2, and 3 were all higher than 20 nm / min. Among them, Comparative Example 1 did not add phase stabilizers and sintering aids, resulting in a loose coating structure with many defects. Etching gas could quickly penetrate and erode the coating, with an etching rate as high as 28.5 nm / min. Comparative Example 3 did not undergo substrate pretreatment or bonding underlayer preparation. There were interfacial pores between the coating and the substrate, which allowed etching gas to easily penetrate from the interface, leading to coating peeling and erosion. The etching rate was 25.3 nm / min. Comparative Example 2 did not undergo spray granulation treatment. The coating had many internal pores and an uneven structure. Etching gas could easily accumulate at the pores and erode the coating. The etching rate was 21.7 nm / min.

[0054] By observing the surface morphology of the coatings after etching, it was found that the coatings of Examples 1, 2, and 3 only showed slight erosion marks, without obvious peeling, cracking, and pore expansion, indicating that the coatings have good etching resistance stability. However, the coatings of Comparative Examples 1, 2, and 3 showed obvious erosion pits, peeling, and cracking. In particular, the coating of Comparative Example 1 even showed large-area peeling, indicating that its etching resistance stability was extremely poor.

[0055] Table 2: Performance Test Results of Ceramic Feed Powder and Nano-Suspension in Examples and Comparative Examples

[0056] As shown in Table 2, the ceramic feed powders prepared in Examples 1 and 3 and the nano-ceramic suspension prepared in Example 2 all have excellent performance, which provides a guarantee for the subsequent spraying preparation of high-quality coatings. However, the powders in Comparative Examples 1 and 2 have poor performance, which affects the coating quality.

[0057] The ceramic feed powders in Examples 1 and 3 have particle sizes D50 of 22 μm and 24 μm, respectively, both within the range of 20-25 μm. The particle size distribution is uniform, meeting the requirements for supersonic atmospheric plasma spraying. The nano-ceramic suspension in Example 2 has a particle size D50 of 110 nm, within the range of 80-150 nm. The nanoparticles are uniformly dispersed, fully utilizing the excellent properties of the nanomaterials. The ceramic feed powder in Comparative Example 1 has a particle size D50 of 23 μm, which is within the specified range, but due to the lack of phase stabilizers and sintering aids, the powder is prone to agglomeration during spray granulation, resulting in an uneven particle size distribution. Comparative Example 2 did not undergo spray granulation treatment; the multi-component composite ceramic powder has a particle size D50 of 18 μm, smaller than the specified range, and the particle size distribution is disordered, containing a large amount of fine powder and coarse particles, failing to meet the spraying requirements.

[0058] The ceramic feed powders in Examples 1 and 3 have flowability values ​​of 32s / 50g and 30s / 50g, respectively, both less than 35s / 50g, indicating good flowability. This ensures stable and uniform powder delivery during spraying, preventing powder blockage or uneven delivery, thus ensuring uniform coating thickness and dense structure. The ceramic feed powder in Comparative Example 1 has a flowability of 33s / 50g, which is within the specified range, but due to powder agglomeration, its flowability is slightly worse than the examples. Comparative Example 2 did not undergo spray granulation treatment; its multi-element composite ceramic powder has a flowability of 52s / 50g, far exceeding 35s / 50g, indicating extremely poor flowability. This makes it prone to uneven powder delivery and powder accumulation during spraying, leading to a decline in coating quality.

[0059] The ceramic feed powder in Example 1 corresponds to a slurry with a solid content of 58 wt%, and in Example 3 it is 62 wt%, both falling within the range of 50-65 wt%. This moderate solid content ensures good slurry flowability for spray granulation while maintaining the density and strength of the granulated powder. The nano-ceramic suspension in Example 2 has a solid content of 30 wt%, falling within the range of 25-35 wt%. This moderate solid content ensures the dispersion stability of the suspension and the atomization effect during spraying. The slurry in Comparative Example 1 has a solid content of 58 wt%, the same as in Example 1, but due to powder agglomeration, the slurry uniformity is poor. Comparative Example 2 did not undergo spray granulation and therefore did not require slurry preparation; therefore, no solid content data is available for Comparative Example 2.

[0060] The nano-ceramic suspension in Example 2 exhibited a dispersion stability of 48 hours, indicating that the suspension maintained uniform dispersion without significant precipitation within 48 hours. This was attributed to the addition of polycarboxylate dispersant and pH adjustment, which effectively inhibited the aggregation of nanoparticles. The comparative example did not involve the preparation of the nano-suspension, therefore no dispersion stability data were available.

[0061] The ceramic feed powders or nano-suspensions prepared in Examples 1, 2, and 3 all meet the requirements of this invention in terms of particle size distribution, flowability, solid content, and dispersion stability, and can provide high-quality raw materials for subsequent spraying processes, thereby preparing high-performance etch-resistant ceramic coatings; however, the powder properties of Comparative Examples 1 and 2 do not meet the requirements, resulting in poor coating performance in subsequent preparations.

[0062] Table 3: Effect of in-situ laser remelting assisted process on coating performance

[0063] As shown in Table 3, the in-situ laser remelting assisted process has a significant effect on improving the density, microhardness and etching resistance of the ceramic coating, and is an important optimization method for preparing high-performance etching-resistant ceramic coatings in this invention.

[0064] Examples 1 and 2, which incorporated in-situ laser remelting, achieved coating densities of 98.2% and 97.8%, respectively. Example 3, which did not incorporate this process, had a coating density of 95.5%, a difference of approximately 2.5 percentage points. This difference is because the in-situ laser remelting process utilizes a high-energy-density laser beam with rapid heating and cooling capabilities. This allows the freshly deposited coating surface to melt rapidly. The molten material flows under surface tension, filling micropores and defects within the coating, while simultaneously solidifying quickly to form a dense microstructure, thus significantly improving coating density. Furthermore, laser remelting promotes grain refinement within the coating, reducing porosity at grain boundaries and further enhancing coating density. This aligns with existing research demonstrating that laser remelting can improve the microstructure and density of sprayed coatings.

[0065] Examples 1 and 2 introduced in-situ laser remelting assisted processes, resulting in coating microhardness of 1280 HV and 1320 HV respectively. Example 3, without this process, had a coating microhardness of 1150 HV, a difference of approximately 130-170 HV. This is because laser remelting refines the coating grains. According to the Hall-Page relationship, grain refinement significantly improves material hardness. Simultaneously, laser remelting eliminates internal defects and stress concentrations in the coating, making the coating structure more uniform and further enhancing hardness. Example 2 used a laser power of 350 W, slightly lower than the 400 W in Example 1, but achieved higher microhardness. This is because Example 2 employed nano-suspension plasma spraying; the nanoparticles themselves possess high hardness, and combined with the grain refinement effect of laser remelting, the coating hardness reached an even higher level.

[0066] Examples 1 and 2 introduced in-situ laser remelting assisted processes, resulting in coating etching rates of 10.8 nm / min and 9.6 nm / min, respectively. Example 3, without this process, showed an etching rate of 14.2 nm / min. Introducing laser remelting reduced the etching rate by approximately 3.4-4.6 nm / min, significantly improving etching resistance. This is because laser remelting increases coating density, reduces porosity and defects within the coating, making it difficult for etching gases to penetrate and thus reducing the reaction between etching gases and coating components. Simultaneously, laser remelting makes the coating surface smoother and more even, reducing the adsorption and aggregation of etching gases, further lowering the etching rate. Furthermore, laser remelting promotes the formation of a dense oxide film on the coating surface, which effectively blocks the erosion of etching gases and improves the coating's etching resistance. This aligns with research findings that the dense structure in Y2O3 coatings prepared by suspension plasma spraying enhances their resistance to plasma etching.

[0067] It should be noted that the parameters of the in-situ laser remelting assisted process need to be properly controlled. If the laser power is too high, it will lead to over-melting of the coating, resulting in problems such as coarse grains and cracking, which will reduce the coating performance. If the laser power is too low, an effective remelting effect cannot be achieved, and it will be difficult to significantly improve the coating performance. The laser powers selected in Examples 1 and 2 are 400W and 350W, respectively, both within the range of 300-500W, which can achieve the best remelting effect and thus significantly improve the coating performance.

[0068] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an etch-resistant ceramic coating, characterized in that, Includes the following steps: Step S1: Prepare multi-component composite ceramic powder based on phase equilibrium design; Step S2: Spray granulation treatment is performed on the multi-component composite ceramic powder prepared in step S1. Step S3: The powder obtained in step S2 is used to prepare a coating by plasma spraying.

2. The method for preparing the etch-resistant ceramic coating according to claim 1, characterized in that, Step S1 specifically includes: selecting yttrium oxide and yttrium fluoride powders with a purity of not less than 99.999% as basic raw materials, and weighing and mixing them according to a molar ratio of 1:(0.2-0.5); adding zirconium oxide (3-8 wt% of total mass) and alumina (1-3 wt% of total mass) as phase stabilizers and sintering aids to the mixed powder; placing all the powder in a planetary ball mill, using ethanol as the dispersion medium, zirconium oxide balls as grinding balls, a ball-to-material ratio of 5:1, and a rotation speed of 300 rpm, and performing wet ball milling for 12-24 hours; after ball milling, drying the slurry at 80°C, and then calcining it at 1200-1400°C for 2-4 hours under an argon atmosphere, followed by crushing and passing it through a 400-mesh sieve to obtain the multi-component composite ceramic powder.

3. The method for preparing the etch-resistant ceramic coating according to claim 2, characterized in that, Step S2 specifically includes: mixing the multi-component composite ceramic powder obtained in step S1 with deionized water, dispersant, and binder at a mass ratio of 100:(40-60):(0.5-1.5):(3-8) to prepare a slurry with a solid content of 50-65wt%; the dispersant is ammonium polyacrylate, and the binder is polyvinyl alcohol; feeding the slurry into a centrifugal spray drying tower, controlling the inlet temperature at 180-220℃, the outlet temperature at 90-110℃, the atomizing disc speed at 10000-15000 rpm, and the feed rate at 10-20 mL / min; collecting the obtained spherical powder and heat-treating it at 500-600℃ for 1-2 hours to remove organic components, finally obtaining ceramic feed powder with a particle size distribution D50 of 20-25μm and a flowability of less than 35 s / 50g.

4. The method for preparing the etch-resistant ceramic coating according to claim 3, characterized in that, Step S3 is a supersonic atmospheric plasma spraying process, specifically including: feeding the ceramic feed powder obtained in step S2 into a 9M powder feeder, using argon as the main gas with a flow rate of 40-50 slpm and hydrogen as the secondary gas with a flow rate of 10-15 slpm; setting the spraying power to 40-50 kW, the spraying distance to 100-120 mm, the spray gun moving speed to 800-1000 mm / s, and controlling the single-pass thickness to 10-20 μm; preheating the substrate to 300-400℃ before starting spraying until the coating thickness reaches 200-500 μm.

5. The method for preparing the etch-resistant ceramic coating according to claim 1, characterized in that, Between steps S1 and S2, a nano-suspension preparation step is also included: taking the calcined but unsieved multi-component composite ceramic powder block from step S1, and performing secondary grinding using a high-energy nano-sand mill, with 0.3 mm diameter zirconia beads as the grinding medium, grinding for 6-10 hours to obtain a nano-ceramic slurry with an average particle size D50 of 80-150 nm; adding 2% by mass of polycarboxylate dispersant to the slurry, adjusting the pH value to 9-10, and after ultrasonic dispersion and vacuum defoaming, obtaining a nano-ceramic suspension with a solid content of 25-35 wt%.

6. The method for preparing the etch-resistant ceramic coating according to claim 5, characterized in that, Step S3 is a suspension plasma spraying process, specifically including: placing the nano-ceramic suspension prepared in claim 5 into a magnetically stirred storage tank, and using a screw pump to deliver it to a two-stage atomizing nozzle at a rate of 20-30 mL / min; the atomizing gas is nitrogen, with a pressure of 0.3-0.5 MPa; using an F4-MB type plasma spray gun, with a mixture of argon and hydrogen as the working gas, a current of 500-600 A, and a voltage of 50-60 V; the spraying distance is 60-80 mm, the spray gun scanning speed is 300-500 mm / s, and a coating is deposited on a substrate preheated to 400-500℃.

7. The method for preparing an etch-resistant ceramic coating according to any one of claims 1, 4, or 6, characterized in that, Before plasma spraying in step S3, the metal or ceramic substrate is pretreated, including: roughening the substrate surface by sandblasting with brown corundum sand with a particle size of 24 mesh to achieve a surface roughness Ra of 4-6 μm; ultrasonic cleaning with anhydrous ethanol after sandblasting, and spraying immediately after drying.

8. The method for preparing the etch-resistant ceramic coating according to claim 7, characterized in that, After sandblasting and cleaning, a bonding underlayer is first sprayed onto the pretreated substrate surface. The bonding underlayer material is NiCrAlY alloy powder with a particle size of -140 to +325 mesh. An atmospheric plasma spraying process is used to prepare a bonding underlayer with a thickness of 50-80 μm under the conditions of argon flow rate of 40 slpm, hydrogen flow rate of 10 slpm, power of 30 kW, and spraying distance of 120 mm.

9. The method for preparing an etch-resistant ceramic coating according to any one of claims 4 or 6, characterized in that, In the plasma spraying process of step S3, an in-situ laser remelting assisted process is introduced: a continuous fiber laser with a wavelength of 1064 nm, a laser power of 300-500 W, and a spot diameter of 2 mm is used. The laser beam is synchronously irradiated on the surface of the newly deposited coating at an angle of 30-45 degrees to the plasma flow. The laser scanning speed is synchronized with the spray gun moving speed.

10. An etch-resistant ceramic coating, prepared by the method for preparing an etch-resistant ceramic coating as described in any one of claims 1 to 9.

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