Suspension plasma spraying aluminum oxide compact wear-resistant coating as well as preparation method and application thereof

Abstract

The invention discloses a suspension plasma spraying aluminum oxide compact wear-resistant coating as well as a preparation method and application thereof. The preparation method comprises the following steps: pretreating a base material; the alumina suspension is applied to the surface of a base material by adopting an axial suspension plasma spraying technology, so that the compact wear-resistant alumina coating is prepared; wherein the technological parameters adopted by the axial suspension plasma spraying technology comprise that the power of a spray gun is 125-150 kW, the spraying distance is 50-150 mm, the liquid feeding rate is 30-120 ml / min, and the surface temperature of the base material in the spraying process is 300-600 DEG C. The method provided by the invention has the characteristics of simplicity and convenience in operation, short production period, controllable coating thickness, high production efficiency and the like, and meanwhile, the prepared aluminum oxide coating reserves the chemical composition of spraying state aluminum oxide; and the method has the advantages of larger preparation size, more compact coating structure, higher bonding strength, higher hardness, lower wear rate and suitability for more matrix types.

Description

Technical Field

[0001] The invention belongs to the field of ceramic coatings on metal surfaces, and in particular relates to a suspension plasma sprayed alumina dense wear-resistant coating and a preparation method and application thereof. Background Art

[0002] Alumina coatings have high hardness, high chemical stability and excellent wear and corrosion resistance and are widely used in the industrial field to ensure that high-end equipment parts can operate stably in harsh service environments, reduce damage to the base material, and extend its service life. Alumina coatings can be used as low-stress abrasive wear, hard surface wear, corrosion resistance to various chemical media and chemical gases, cavitation and erosion coatings at room temperature, and are also used for gas cavitation resistance and high-temperature emission coatings at high temperatures. It has broad application prospects in many industries such as electronics, petroleum, steel metallurgy, mechanical chemical industry, equipment manufacturing, aerospace, etc.

[0003] At present, the methods for preparing alumina coatings include arc ion plating, pulsed laser deposition, micro-arc oxidation, magnetron sputtering, chemical vapor deposition and other methods, but there are still certain challenges for the preparation of dense alumina coatings, such as excessive porosity and incomplete melting of particles. Plasma spraying has the characteristics of high flame temperature, simple process, high efficiency, and excellent coating performance. The plasma spraying technology can quickly deposit alumina ceramic coatings on the substrate, which can organically combine the advantages of alumina ceramic materials and substrates, thereby improving the performance of parts. Although traditional atmospheric plasma spraying (APS) can obtain a fairly wide range of coating structure morphology, traditional plasma spraying is only for 10-100μm powders with good fluidity and limited selection of coating materials, and there are still certain pore defects in the coating structure. A method for preparing porous alumina ceramics is disclosed in the patent with publication number CN118063196A, with a porosity distribution of 8-15%. High porosity is difficult to meet the needs of friction and corrosion environments in production and life. The pores provide channels for friction fatigue and corrosion, which accelerates the failure of the coating.

[0004] At present, it is generally believed that the higher the solid content, the denser the structure. The current plasma spraying power on the market is 60-70kW, which is difficult to achieve high power, making it difficult to completely melt the liquid particles, resulting in various structural defects and waste of raw materials. At the same time, high-concentration suspensions lead to extremely poor fluidity and ductility during spraying, and are prone to powder blockage, making it difficult to achieve spraying of special-shaped workpieces and long-term spraying. In the prior art, it is difficult to prepare high-density coatings with low-concentration suspensions, and it is difficult to achieve good and complete melting of liquid materials with low power. Therefore, it is very important to develop and prepare dense coatings by high-power spraying of low-concentration aqueous suspensions to improve raw material utilization and cost-effectiveness. At the same time, it is very important to develop a high-mechanical strength aluminum oxide coating for engineering applications that can be quickly deposited on various substrates based on suspension plasma spraying. Summary of the invention

[0005] The main purpose of the present invention is to provide a suspension plasma sprayed aluminum oxide dense wear-resistant coating and its preparation method and application, so as to overcome the shortcomings of the prior art.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0007] The embodiment of the present invention provides a method for preparing a dense wear-resistant aluminum oxide coating by plasma spraying of a suspension, which comprises:

[0008] Pre-treating the substrate;

[0009] And, an axial suspension plasma spraying technology is used to apply an alumina suspension to the surface of a substrate, thereby obtaining a dense and wear-resistant alumina coating; wherein the alumina content in the alumina suspension is 10-20wt%, and the dispersant content is 1-5wt%; the process parameters used in the axial suspension plasma spraying technology include: a spray gun power of 125-150kW, a spraying distance of 50-150mm, a liquid delivery rate of 30-120ml / min, and a surface temperature of the substrate of 300-600°C during the spraying process.

[0010] The embodiment of the present invention also provides a dense wear-resistant aluminum oxide coating prepared by the aforementioned preparation method.

[0011] The embodiment of the present invention also provides the application of the aforementioned dense wear-resistant aluminum oxide coating in the field of wear resistance and corrosion protection of white surfaces of special-shaped workpieces.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] (1) The aluminum oxide coating in the present invention utilizes a plasma spraying process, and the aluminum oxide coating thickness and coating structure are effectively controlled by changing the concentration of the aluminum oxide dispersion solution, the concentration of the dispersant, the liquid flow rate, the spraying distance, the spraying power, the movement state of the spray gun, and the number of spraying cycles. Since the aluminum oxide droplets have a high enthalpy value when deposited on the coating, they can form a mechanical bite with various substrates while being efficiently deposited, thereby forming a mechanical bite force that is much stronger than the weak van der Waals force. The deposition efficiency of the coating can be intuitively set by only controlling the movement parameters of the mechanical arm that moves the spray gun. At the same time, a high power of about 140 kW is used to avoid the generation of unmelted particles and semi-melted particles, breaking through the limitation that low-concentration suspensions cannot prepare dense coatings, improving the utilization rate of liquid raw materials, reducing waste and costs, and breaking through the aluminum oxide wear rate limit in the industry, reducing the specific wear rate to 5×10 -16 mm 3 N -1 m -1 the following;

[0014] (2) The spraying process of the aluminum oxide coating in the present invention has the characteristics of simple process, short production cycle, high production efficiency, etc. Compared with the conventional aluminum oxide coating preparation method, the aluminum oxide coating prepared by the present invention has the advantages of larger preparation size, denser coating structure, higher bonding strength, higher hardness, lower wear rate, and more applicable substrate types. At the same time, high power and low solid content make the liquid material have considerable fluidity, and the molten droplet has good ductility, which is more suitable for spraying special-shaped workpieces, and can be used for various aluminum oxide coatings for practical engineering applications, such as having wear resistance, friction reduction, corrosion resistance, etc.;

[0015] (3) The spraying area and layer thickness of the aluminum oxide coating in the present invention can be selected according to the specific function. Increasing the liquid delivery rate or adjusting the spraying distance can change the deposition efficiency of the coating without significantly changing the coating structure. At the same time, the present invention adopts axial suspension plasma spraying to increase the kinetic energy and thermal energy of the liquid material, so that the liquid material is fully melted to achieve a denser flat deposition. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a real photo of the plasma spraying equipment of the present invention;

[0018] Figure 2is a graph of the hardness, dry friction wear rate, and seawater friction wear rate of the Al2O3 coating prepared in Example 1 of the present invention;

[0019] Figure 3a-Figure 3b This is a cross-sectional morphology and organization picture of the Al2O3 coating prepared in Example 1 of the present invention;

[0020] Figure 4a-4b This is a cross-sectional morphology and organization picture of the Al2O3 coating prepared in Example 2 of the present invention;

[0021] Figure 5a-Figure 5b is a friction coefficient curve of the Al2O3 coating prepared in Example 1-2 of the present invention under a load of 10N;

[0022] Figure 6 is a cross-sectional hardness diagram of the Al2O3 coating prepared in the embodiment of the present invention and the comparative example;

[0023] Figure 7a-7d is a dry friction and wear microscopic morphology of the Al2O3 coating prepared in Example 1-2 of the present invention;

[0024] Figure 8 This is a picture of the Al2O3 coating on the surface of the special-shaped workpiece prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0025] In view of the defects of the prior art, the inventors of this case have proposed the technical solution of the present invention after long-term research and extensive practice. It mainly explores the influence of the addition amount of polymer dispersant and different spraying processes on the coating structure and realizes defect control, solves the problems of large number of pores and poor density in the preparation process of alumina coating. The prepared alumina coating has good density, hardness, wear resistance and high bonding strength, which provides convenience for subsequent engineering applications.

[0026] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Specifically, as one aspect of the technical solution of the present invention, a method for preparing a dense wear-resistant aluminum oxide coating by plasma spraying of a suspension comprises:

[0028] Pre-treating the substrate;

[0029] And, an axial suspension plasma spraying technology is used to apply an alumina suspension to the surface of a substrate, thereby obtaining a dense and wear-resistant alumina coating; wherein the alumina content in the alumina suspension is 10-20wt%, and the dispersant content is 1-5wt%; the process parameters used in the axial suspension plasma spraying technology include: a spray gun power of 125-150kW, a spraying distance of 50-150mm, a liquid delivery rate of 30-120ml / min, and a surface temperature of the substrate of 300-600°C during the spraying process.

[0030] In some preferred embodiments, the process parameters used in the axial suspension plasma spraying technology include: the argon flow rate of plasma spraying is 20-30 L / min, the nitrogen flow rate is 50-60 L / min, the hydrogen flow rate is 5-15 L / min, the total gas flow rate is 200-300 L / min, the arc current is 200-240 A, and the atomizing gas flow rate is 10-20 L / min.

[0031] In some preferred embodiments, the preparation method specifically includes: fixing the substrate on a rotating sample table fixture, and preheating the surface of the substrate to 100-300°C, then keeping the rotating sample table fixture rotating or flipping, the axis of the spray gun is orthogonal to the surface of the substrate, and the spray gun reciprocates up and down; wherein the rotation speed of the rotating sample table fixture is 150-250R / min, the up and down movement speed of the spray gun is 15-25mm / min, and the number of spray gun cycles is 100-200 times.

[0032] Furthermore, the surface of the substrate is preheated to 100-300° C. by plasma flame scanning; wherein the number of cycles of the plasma flame scanning is 2 to 4 times.

[0033] Furthermore, the material of the substrate includes any one of metal, ceramic, glass, and plastic, but is not limited thereto.

[0034] Furthermore, the thickness of the substrate is 1-100 mm.

[0035] Furthermore, the substrate includes a special-shaped workpiece substrate, but is not limited thereto.

[0036] In some preferred embodiments, the preparation method specifically includes: cleaning and sandblasting the substrate, and then using a high-pressure air gun to blow away floating dust on the surface of the substrate.

[0037] Furthermore, ethanol is used to perform ultrasonic cleaning on the substrate; wherein the frequency of the ultrasonic cleaning is 20-80 Hz, and the cleaning time is 10-20 minutes.

[0038] Furthermore, the sandblasting treatment is performed using aluminum oxide grit; wherein the aluminum oxide grit includes aluminum oxide white corundum sand, and the particle size of the aluminum oxide white corundum sand is 80-120 meshes.

[0039] Furthermore, the pressure used in the sandblasting process is 0.5-1.0 MPa.

[0040] In some preferred embodiments, the method for preparing the dense wear-resistant aluminum oxide coating by suspension plasma spraying comprises the following steps:

[0041] The substrate is cleaned and then sandblasted, and the dust on the surface of the obtained substrate is blown off with a high-pressure air gun; the surface of the obtained substrate is preheated to 100-300°C, and then an aluminum oxide suspension is deposited on the surface of the substrate through a spray gun using a suspension plasma spraying technology to obtain an aluminum oxide coating; the concentration of the aluminum oxide suspension is 10-20wt.%, and the concentration of the dispersant is 1-5wt.%; the power of the spray gun is 125-150kW; the spraying distance is 50-150mm; the liquid delivery rate is 30-120ml / min; the surface temperature of the substrate during the spraying process is 300-600°C.

[0042] In the process of preparing the dense wear-resistant aluminum oxide coating, the present invention first cleans the substrate and then performs sandblasting.

[0043] The cleaning may specifically be carried out by ultrasonic cleaning to remove oil, dust and debris on the surface of the base substrate. The cleaning agent in this application uses ethanol. Compared with deionized water, ethanol has a better cleaning effect. Compared with other organic solvents, ethanol is more green, economical and safe. The ultrasonic cleaning time is 10 to 20 minutes, and the frequency of ultrasonic treatment is 20-80Hz. . The specific operation method of the sandblasting is carried out in a manner well known to those skilled in the art. The sandblasting is to increase the surface roughness of the substrate and improve the mechanical bite force between the substrate and the coating to enhance the bonding strength of the coating. In the present invention, alumina white corundum sand is selected for sandblasting, and the pressure of sandblasting is 0.5 to 1MPa. The surface of the substrate is repeatedly and evenly sandblasted until it is rough and non-reflective.

[0044] The present invention fixes the substrate on a rotating sample table, maintains rotation during spraying, the axis of the spray gun is orthogonal to the surface of the substrate, and the spray gun performs up and down reciprocating motion. The rotation of the sample table is coordinated with the movement speed of the spray gun to increase the surface speed of the substrate, thereby improving the density of the coating. More specifically, the rotation speed of the rotating sample table fixture is 150-250R / min, the up and down movement speed of the spray gun is 15-25mm / min, and the number of spray gun cycles is 100-200 times.

[0045] The present invention then performs a preheating treatment on the substrate, and the preheating treatment increases the temperature of the substrate. The preheating treatment can reduce the temperature difference between the substrate and the coating, avoid cracking and peeling of the coating due to thermal stress caused by excessive temperature difference, and is conducive to the growth of columnar grains in the coating to hinder crack propagation, thereby enhancing the bonding strength between the coating and the substrate. The present invention uses a plasma flame flow to scan and preheat the surface of the substrate, so that the substrate temperature is 100-300°C.

[0046] Finally, the present invention uses a suspension plasma spraying of an aluminum oxide coating on the surface of the substrate. In the present invention, a suspension prepared with aluminum oxide powder is specifically used for suspension plasma spraying on the surface of the substrate to obtain an aluminum oxide coating. The aluminum oxide powder has a particle size of 1 to 5 μm, and the increased particle size improves the spraying deposition efficiency to a greater extent. The suspension solvent is deionized water, which avoids the introduction of unnecessary C impurities caused by organic solvents, and is more green, economical, and safe.

[0047] In the method for preparing aluminum oxide coating of the present invention, the argon flow rate of plasma spraying is 20-30 L / min, the nitrogen flow rate is 50-60 L / min, the hydrogen flow rate is 5-15 L / min, the total gas flow rate is 200-300 L / min, the arc current is 200-240A, and the atomizing gas flow rate is 10-20 L / min.

[0048] The present invention solves the coating defect problem, such as pores, cracks and unmelted particle distribution, by optimizing the above parameters of suspension plasma spraying. The thickness of the aluminum oxide coating is 100-600 μm.

[0049] Furthermore, the process parameters to be optimized are mainly the liquid delivery volume, the spraying distance and the amount of suspension dispersant added.

[0050] The present invention then uses a scanning electron microscope to observe the cross-sectional micromorphology of the prepared coating and conduct a microhardness test, and detects the friction and wear performance of the aluminum oxide coating, specifically including: pre-treating the surface of the suspension plasma sprayed coating, and the pre-treatment process includes grinding with a 800-2000# diamond grinding disc and then polishing.

[0051] Furthermore, the friction and wear performance test uses 6 mm Al2O3 as a counter-wear pair, and reciprocating friction motion is performed for 30 minutes under a load of 10N.

[0052] Figure 1 The actual photo of the plasma spraying equipment used in the present invention is as follows Figure 1 shown.

[0053] Another aspect of the embodiments of the present invention further provides a dense wear-resistant aluminum oxide coating prepared by the aforementioned preparation method.

[0054] Furthermore, the thickness of the dense wear-resistant aluminum oxide coating is 100 to 600 μm.

[0055] Furthermore, the porosity of the alumina dense wear-resistant coating is 0.5% to 4.5%.

[0056] Furthermore, the friction specific wear rate of the alumina dense wear-resistant coating is 4 to 25×10 -16 mm 3 N -1 m -1 .

[0057] Another aspect of the embodiments of the present invention further provides the application of the aforementioned dense wear-resistant aluminum oxide coating in the field of wear resistance and corrosion protection of white surfaces of special-shaped workpieces.

[0058] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and drawings. This embodiment is implemented on the premise of the technical solution of the invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0059] Unless otherwise specified, the experimental materials used in the following examples can be purchased from conventional biochemical reagent companies.

[0060] Example 1

[0061] (1) Prefabricated alumina suspension: using a solid content of 20 wt.%, polyethyleneimine as a dispersant, a dispersant concentration of 2.5 wt.%, and deionized water as a solvent, and fully ball milling for 24 hours.

[0062] (2) Substrate: The substrate is a titanium alloy Ti80 substrate with surface sandblasting treatment. The experimental sample is as follows Figure 8 After the sandblasting is completed, use a compressed air high-pressure air gun to clean the remaining spray, particles and dust on the surface of the substrate, and install it on the rotating specimen table fixture.

[0063] (3) Spraying technology: The surface of the substrate is preheated to 150°C by plasma flame scanning, and the spraying process parameters are set. The suspension plasma spraying technology is used to deposit the aluminum oxide suspension on the surface of the substrate through the axial feeding of the spray gun to obtain the aluminum oxide coating; the movement of the spray gun is achieved by setting up a plasma spray gun on a mechanical arm, the movement speed of the mechanical arm is set to 15 mm / s, the spraying distance is 120 mm, and the number of spraying cycles is 150 times. The turntable speed is set to 225 R / min to increase the surface speed of the substrate.

[0064] The argon flow rate was 25 L / min, the nitrogen flow rate was 60 L / min, the hydrogen flow rate was 15 L / min, the total gas flow rate was 220 L / min, the arc current was 220 A, the spraying power was 140 kW, the liquid delivery rate was 60 ml / min, the atomizing gas flow was 15 L / min, and the surface temperature of the substrate during the spraying process was 400 ° C. Compressed air was used to cool the sample during the spraying process to prevent the sample from overheating.

[0065] Furthermore, when the suspension is fed, a peristaltic pump is used to transport the suspension from its containing container to the suspension nozzle, and the suspension is ejected through the nozzle and injected into the plasma flame flow at a high speed in the axial direction.

[0066] Furthermore, during the spraying process, the rotating sample table fixture maintains a rotating motion, the axis of the spray gun is orthogonal to the surface of the substrate, and the spray gun performs an up and down reciprocating motion.

[0067] Furthermore, after the spraying is completed, the substrate is cooled to about room temperature and then removed from the sample table fixture for subsequent characterization tests. Subsequent characterization tests have found that the aluminum oxide coating prepared using the water-based suspension of the present application has a typical layered structure with high density. The cross-section and microstructure of the coating are as follows: Figure 3a-Figure 3b The coating thickness is about 581.7 μm, the coating porosity is about 0.9%, and the wear rate under dry friction conditions is 5.39×10 -16 mm 3 N -1 m -1 The wear rate under seawater friction conditions is 4.98×10 -16 mm 3 N -1 m -1 Dense wear-resistant coating.

[0068] Example 2

[0069] (1) Prefabricated alumina suspension: using a solid content of 20 wt.%, polyethyleneimine as a dispersant, a dispersant concentration of 2.5 wt.%, and deionized water as a solvent, and fully ball milling for 24 hours.

[0070] (2) Substrate: The substrate is made of stainless steel 316L substrate with surface sandblasting treatment. The size of the experimental sample is 25.4 mm × 3 mm. After sandblasting, a compressed air high-pressure air gun is used to clean the residual spray, particles and dust on the surface of the substrate, and it is installed on the rotating sample table fixture.

[0071] (3) Spraying technology: The surface of the substrate was preheated to 200°C by plasma flame scanning, and the spraying process parameters were set. The suspension plasma spraying technology was used to deposit the aluminum oxide suspension on the surface of the substrate through the axial delivery of the spray gun to obtain the aluminum oxide coating; the movement of the spray gun was achieved by setting up a plasma spray gun on a robotic arm, and the movement speed of the robotic arm was set to 15 mm / s, the spraying distance was 125 mm, and the number of spraying cycles was 150 times. The turntable speed was set to 225 R / min to increase the surface speed of the substrate. The argon flow rate was 25 L / min, the nitrogen flow rate was 60 L / min, the hydrogen flow rate was 15 L / min, the total gas flow rate was 220 L / min, the arc current was 220 A, the spraying power was 140 kW, the liquid delivery rate was 45 ml / min, the atomizing gas flow was 15 L / min, and the surface temperature of the substrate during the spraying process was 500°C. Compressed air was used to cool the sample during the spraying process to prevent the sample from overheating.

[0072] Furthermore, when the suspension is fed, a peristaltic pump is used to transport the suspension from its containing container to the suspension nozzle, and the suspension is ejected through the nozzle and injected into the plasma flame flow at a high speed in the axial direction.

[0073] Furthermore, during the spraying process, the rotating sample table fixture maintains a rotating motion, the axis of the spray gun is orthogonal to the surface of the substrate, and the spray gun performs an up and down reciprocating motion.

[0074] Furthermore, after the spraying is completed, the substrate is cooled to about room temperature and then removed from the sample table fixture for subsequent characterization tests. Subsequent characterization tests have found that the aluminum oxide coating prepared using the water-based suspension of the present application has a typical layered structure with high density. The cross-section and microstructure of the coating are as follows: Figure 4a-4b The coating thickness is about 210.5 μm, the coating porosity is about 1.9%, and the wear rate under dry friction conditions is 5.37×10 -16 mm 3 N -1 m -1 The wear rate under seawater friction conditions is 5.25×10 -16 mm 3 N -1 m -1 Dense wear-resistant coating.

[0075] Comparative Example 1

[0076] (1) Ti80 titanium alloy was selected as the substrate.

[0077] (2) The concentration of the dispersant in the suspension preparation was 2.5 wt.% relative to the solid content.

[0078] (3) Process parameters of suspension plasma spraying: the liquid feeding rate is 30 ml / min, and the others are the same as those in Example 1.

[0079] (4) The coating thickness is about 245.6 μm, the coating porosity is about 3.4%, and the wear rate under dry friction conditions is 20.26×10 -16 mm 3 N -1 m -1 The wear rate under seawater friction conditions is 10.58×10 -16 mm 3 N -1 m -1 This indicates that as the liquid feeding amount decreases, the too low liquid feeding rate makes the particles in the plasma flame more easily affected by the flame flow and deflected, the coating porosity increases, the density decreases, and thus the friction and wear performance decreases.

[0080] The coating performed poorly after testing and was not suitable for practical application.

[0081] Comparative Example 2

[0082] (1) Ti80 titanium alloy was selected as the substrate.

[0083] (2) The concentration of the dispersant in the suspension preparation was 2.5 wt.% relative to the solid content.

[0084] (3) Process parameters of suspension plasma spraying: The spraying distance is 110 mm, and the rest is the same as in Example 1.

[0085] (4) The coating thickness is about 266.8 μm, the coating porosity is about 1.6%, and the wear rate under dry friction conditions is 12.92×10 -16 mm 3 N -1 m -1 The wear rate under seawater friction conditions is 4.27×10 -16 mm 3 N -1 m -1 This indicates that the increase in spraying distance reduces the kinetic energy and momentum of the particles, which increases the porosity of the coating. The performance of the coating after testing is too poor and is not suitable for practical applications.

[0086] Comparative Example 3

[0087] (1) Ti80 titanium alloy was selected as the substrate.

[0088] (2) The concentration of the dispersant in the suspension preparation was 2.5 wt.% relative to the solid content.

[0089] (3) Process parameters of suspension plasma spraying: The spraying distance is 115 mm, and the rest is the same as in Example 1.

[0090] (4) The coating thickness is about 135.1 μm, the coating porosity is about 1.8%, and the wear rate under dry friction conditions is 13.09×10-16 mm 3 N -1 m -1 The wear rate under seawater friction conditions is 11.34×10 -16 mm 3 N -1 m -1 After testing, the coating had poor performance and was not suitable for practical application.

[0091] Comparative Example 4

[0092] (1) Ti80 titanium alloy was selected as the substrate.

[0093] (2) The concentration of the dispersant in the suspension preparation was 2.5 wt.% relative to the solid content.

[0094] (3) Process parameters of suspension plasma spraying: The spraying distance is 125 mm, and the rest is the same as in Example 1.

[0095] (4) The coating thickness is about 319.9 μm, the coating porosity is about 2.22%, and the wear rate under dry friction conditions is 5.96×10 -16 mm 3 N -1 m -1 The wear rate under seawater friction conditions is 7.46×10 -16 mm 3 N -1 m -1 After testing, the coating had poor performance and was not suitable for practical application.

[0096] Comparative Example 5

[0097] (1) Ti80 titanium alloy was selected as the substrate.

[0098] (2) The concentration of the dispersant in the suspension preparation was 2.5 wt.% relative to the solid content.

[0099] (3) Process parameters of suspension plasma spraying: The spraying distance is 130 mm, and the rest is the same as in Example 1.

[0100] (4) The coating thickness is about 324.9 μm, the coating porosity is about 3.85%, and the wear rate under dry friction conditions is 12.08×10 -16 mm 3 N -1 m -1 The wear rate under seawater friction conditions is 11.35×10 -16 mm 3 N -1 m -1 After testing, the coating had poor performance and was not suitable for practical application.

[0101] Comparative Example 6

[0102] (1) Ti80 titanium alloy was selected as the substrate.

[0103] (2) The concentration of the dispersant in the suspension preparation was 1 wt.% relative to the solid content.

[0104] (3) The suspension plasma spraying process parameters follow those of Example 1.

[0105] (4) The coating thickness is about 188.1 μm, the coating porosity is about 4.23%, and the wear rate under dry friction conditions is 9.46×10 -16 mm 3 N -1 m -1 The wear rate under seawater friction conditions is 7.75×10 -16 mm 3 N -1 m -1 After testing, the coating had poor performance and was not suitable for practical application.

[0106] Comparative Example 7

[0107] (1) Ti80 titanium alloy was selected as the substrate.

[0108] (2) The concentration of the dispersant in the suspension preparation was 4 wt.% relative to the solid content.

[0109] (3) The suspension plasma spraying process parameters follow those of Example 1.

[0110] (4) The coating thickness is about 193.7 μm, the coating porosity is about 3.09%, and the wear rate under dry friction conditions is 17.95×10 -16 mm 3 N -1 m -1 The wear rate under seawater friction conditions is 9.64×10 -16 mm 3 N -1 m -1 After testing, the coating had poor performance and was not suitable for practical application.

[0111] Comparative Example 8

[0112] (1) Ti80 titanium alloy was selected as the substrate.

[0113] (2) The suspension was prepared with a solid content of 5 wt.%, and the rest was the same as in Example 1.

[0114] (3) The coating thickness is about 127.1 μm, the coating porosity is about 8.09%, and the wear rate under dry friction conditions is 47.95×10 -16 mm 3 N -1 m-1 The wear rate under seawater friction conditions is 19.44×10 -16 mm 3 N -1 m -1 After testing, the coating had poor performance and was not suitable for practical application.

[0115] Comparative Example 9

[0116] (1) Ti80 titanium alloy was selected as the substrate.

[0117] (2) The suspension was prepared with a solid content of 25 wt.%, and the rest was the same as in Example 1.

[0118] (3) The coating thickness is about 591.1 μm, the coating porosity is about 6.18%, and there are incompletely melted particles. The wear rate under dry friction conditions is 21.84×10 -16 mm 3 N -1 m -1 The wear rate under seawater friction conditions is 12.83×10 -16 mm 3 N -1 m -1 After testing, the coating had poor performance and was not suitable for practical application.

[0119] Comparative Example 10

[0120] (1) Ti80 titanium alloy was selected as the substrate.

[0121] (2) Process parameters of suspension plasma spraying: Spraying power is 100 kW, and the rest are the same as in Example 1.

[0122] (3) The coating thickness is about 160.8 μm, the coating porosity is about 5.93%, there are unmelted particles, and the wear rate under dry friction conditions is 25.31×10 -16 mm 3 N -1 m -1 The wear rate under seawater friction conditions is 17.56×10 -16 mm 3 N -1 m -1 After testing, the coating had poor performance and was not suitable for practical application.

[0123] Performance characterization: Figure 2 is the hardness, dry friction wear rate, and seawater friction wear rate of the Al2O3 coating prepared in Example 1 of the present invention; Figure 3a-Figure 3b This is a cross-sectional morphology and organization picture of the Al2O3 coating prepared in Example 1 of the present invention; Figure 4a-4b This is a cross-sectional morphology and organization picture of the Al2O3 coating prepared in Example 2 of the present invention; Figure 5a-Figure 5b is the friction coefficient curve of the Al2O3 coating prepared in Example 1-2 of the present invention under a load of 10N; Figure 6 is a cross-sectional hardness diagram of the Al2O3 coating prepared in the embodiment of the present invention and the comparative example; Figure 7a-7d is a dry friction and wear microscopic morphology of the Al2O3 coating prepared in the embodiment of the present invention, which, Figure 7a , Figure 7c is a microscopic morphology diagram of Example 1, Figure 7b , Figure 7d This is the microscopic morphology of Example 2.

[0124] The present invention first changes the viscosity of the suspension by changing the amount of suspension dispersant added, changes the liquid feeding amount and the spraying distance, thereby affecting the diameter of the suspension mist in the plasma flame flow and the size of the atomized droplets, as well as the heat momentum of the droplets in the plasma flame flow, thereby controlling the size and shape of the formed deposits, thereby changing the coating structure, and thus obtaining a dense aluminum oxide coating. Because the embodiment has a good coating structure and cohesive strength (with a higher hardness), it has good wear resistance. Figure 7a-7d It can be observed from the friction and wear morphology that the dry friction and wear mechanism of the embodiment is mainly typical abrasive wear and weak adhesive wear. No cracks, peeling and transfer of coating materials are observed, which shows that the coating has a certain ability to resist external micro-motion wear and other wear under actual friction and wear conditions. The dense structure also prevents external corrosive media from entering the coating through the holes to corrode the substrate.

[0125] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0126] It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific implementation cases. Any technical deformation made according to the technical solution of the present invention without departing from the scope of protection of the purpose of the present invention and the claims shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a dense wear-resistant coating of aluminum oxide by suspension plasma spraying, characterized in that: include: Pre-treating the substrate; And, an axial suspension plasma spraying technology is used to apply an alumina suspension to the surface of a substrate, thereby obtaining a dense and wear-resistant alumina coating; wherein the alumina content in the alumina suspension is 10-20wt%, and the dispersant content is 1-5wt%; the process parameters used in the axial suspension plasma spraying technology include: a spray gun power of 125-150kW, a spraying distance of 50-150mm, a liquid delivery rate of 30-120ml / min, and a surface temperature of the substrate of 300-600°C during the spraying process.

2. The preparation method according to claim 1, characterized in that: The process parameters adopted by the axial suspension plasma spraying technology include: the argon flow rate of plasma spraying is 20-30L / min, the nitrogen flow rate is 50-60L / min, the hydrogen flow rate is 5-15L / min, the total gas flow rate is 200-300L / min, the arc current is 200-240A, and the atomizing gas flow rate is 10-20L / min.

3. The preparation method according to claim 1, characterized in that: Specifically include: Fix the substrate on the rotating sample table fixture, and preheat the surface of the substrate to 100-300°C, then keep the rotating sample table fixture rotating or flipping, the axis of the spray gun is orthogonal to the surface of the substrate, and the spray gun reciprocates up and down; wherein the rotation speed of the rotating sample table fixture is 150-250R / min, the up and down movement speed of the spray gun is 15-25mm / min, and the number of spray gun cycles is 100-200 times.

4. The preparation method according to claim 3, characterized in that: Preheating the surface of the substrate to 100-300° C. by plasma flame scanning; wherein the number of cycles of the plasma flame scanning is 2 to 4 times; And / or, the material of the substrate includes any one of metal, ceramic, glass, and plastic; And / or, the thickness of the substrate is 1-100 mm; And / or, the substrate comprises a special-shaped workpiece substrate.

5. The preparation method according to claim 1, characterized in that: Specifically include: The substrate is cleaned and sandblasted, and then the dust on the surface of the substrate is blown away with a high-pressure air gun.

6. The preparation method according to claim 5, characterized in that: Specifically include: The substrate is ultrasonically cleaned with ethanol; wherein the frequency of the ultrasonic cleaning is 20-80 Hz and the cleaning time is 10-20 minutes.

7. The preparation method according to claim 5, characterized in that: Alumina grit is used for the sandblasting treatment; wherein the alumina grit includes alumina white corundum grit, and the particle size of the alumina white corundum grit is 80-120 mesh; And / or, the pressure used in the sandblasting process is 0.5-1 MPa.

8. A dense wear-resistant aluminum oxide coating prepared by the preparation method according to any one of claims 1 to 7.

9. The dense wear-resistant aluminum oxide coating according to claim 8, characterized in that: The thickness of the alumina dense wear-resistant coating is 100 to 600 μm; And / or, the porosity of the alumina dense wear-resistant coating is 0.5% to 4.5%; And / or, the friction specific wear rate of the alumina dense wear-resistant coating is 4 to 25×10 -16 mm 3 N -1 m -1 .

10. Use of the dense wear-resistant aluminum oxide coating according to claim 8 or 9 in the field of wear resistance and corrosion protection of white surfaces of special-shaped workpieces.

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