Plasma thermal spraying-hot rolling in-situ forming system and method for titanium alloy ultrahigh-temperature ceramic coating

Abstract

The invention relates to a plasma thermal spraying-hot rolling in-situ forming system and method for a titanium alloy ultrahigh-temperature wear-resistant ceramic coating. The plasma thermal spraying-hot rolling in-situ forming system comprises a heating unit, a plasma thermal spraying unit and a hot rolling unit. The titanium alloy is conveyed to the plasma thermal spraying unit after being subjected to electromagnetic induction heating; the high-melting-point ceramic composite powder is subjected to plasma high-temperature melting and then sprayed to the high-temperature titanium alloy, a ceramic melting layer is formed, then the ceramic melting layer and the titanium alloy are conveyed to a hot rolling unit together, and in-situ film forming-forming-forming rolling is carried out. By the adoption of the plasma thermal spraying-hot rolling composite system, by means of the high-temperature efficiency of plasma, the high-stress forming advantage of a roller and the preheating and heat preservation characteristics of high-temperature titanium alloy, generation of a metallurgical layer between a ceramic coating and the titanium alloy can be effectively promoted, air holes in the coating are inhibited, thermal stress cracks in the coating are reduced, and the service life of the coating is prolonged. And therefore, the ultrahigh-temperature ceramic coating with high hardness and high interface bonding performance is obtained, and the ultrahigh-temperature extreme environment wear resistance of the titanium alloy is finally improved.

Description

Technical Field

[0001] The invention relates to the technical field of advanced alloy material forming properties, and in particular to a plasma thermal spraying-hot rolling in-situ forming system and method for ultra-high temperature wear-resistant ceramic coating of titanium alloy. Background Art

[0002] Titanium alloys have high strength, good hardness, excellent high temperature resistance and corrosion resistance. With the development of modern industry and infrastructure, the application scenarios of titanium alloy parts are becoming more and more extensive. However, in increasingly severe working environments, such as ultra-high temperature environments, the thermal stability and mechanical properties of titanium alloys will be significantly reduced, and the wear resistance and corrosion resistance in the corrosion-abrasive wear environment are slightly insufficient, resulting in increased wear and corrosion on the titanium alloy surface, which in turn shortens the service life of parts and causes huge economic losses.

[0003] The hardness, high temperature resistance and corrosion resistance of ceramic materials are much higher than those of titanium alloy materials. Therefore, they can better resist material deformation failure induced by external loads in extreme service environments such as high temperature contact friction and corrosion-abrasive wear environments, and can effectively reduce high temperature mechanical wear and corrosion wear of parts. In recent years, the use of ceramic powders to modify the surface of titanium alloys is an effective means to improve the wear resistance of titanium alloys in ultra-high temperature extreme service environments, and has become a research hotspot in the field of advanced alloy material forming technology.

[0004] At present, there are many methods for preparing ceramic coatings on the surface of advanced alloy materials, such as plasma thermal spraying technology and laser cladding technology. Plasma thermal spraying technology prepares ceramic layers. The powder is instantly heated to a molten state by high-temperature plasma, and then quickly sprayed onto the metal surface to form a coating. The characteristics are high spraying efficiency and high spraying temperature, which can ensure the high density of the coating. However, the metal matrix is ​​at room temperature during the spraying process, resulting in the inability to undergo high-temperature metallurgical reactions between the matrix metal elements and the coating. Therefore, the interface bonding is weak, and pores are easily left inside the coating, which ultimately affects the mechanical properties of the coating. Laser cladding technology uses the rapid heating effect of a high-power laser beam to simultaneously melt the metal matrix and ceramic composite powder to form a ceramic-metal mixed melt, which is then cooled to form a layer of metal-ceramic composite coating. However, the process characteristics of rapid heating and rapid cooling of laser cladding can cause thermal cracks between the substrate and the coating and inside the coating. At the same time, when the ceramic powder melts rapidly, the residual gas between the powders cannot be discharged, which in turn leads to residual pores in the coating, which ultimately affects the mechanical properties of the coating. Patent CN116479417A proposes a method for preparing a composite coating by high-speed laser cladding of pure ceramic powder. The dilution degree of the base material is controlled by adjusting the laser parameters, thereby forming a metal-ceramic composite coating with a continuous gradient structure, reducing the difference in properties between the base material and the ceramic coating, and inhibiting the cracking of the coating. However, this patent is still a "pressureless" film-forming technology using a single laser at high temperature. The ceramic melt is naturally cooled and the film is formed without an external load. Therefore, the problems of uneven porosity and thickness of the coating cannot be eliminated, resulting in relatively poor wear resistance of the product in high-temperature wear and corrosive environments. Patent CN115747789A proposes a device and method for preparing a crack-resistant laser cladding coating. The surface of the substrate is pre-treated by electroplating to form a reticulated layer, thereby reducing the difference in properties between the substrate and the coating. At the same time, the heating and heat preservation effect of the heating chamber is used to reduce the thermal stress during laser cladding, thereby inhibiting the cracking of the coating. However, there is no external load or force in the process of preparing the ceramic coating in this patent, and the molten layer of the ceramic powder is still formed "without pressure" by natural cooling, resulting in a large number of pores inside the coating and uneven coating thickness. In addition, the electroplating pretreatment process increases the preparation cost of the coating. Patent CN118685728A proposes a method and application of constructing a ceramic-based self-lubricating, highly wear-resistant and highly anti-corrosion coating based on thermal spraying technology. By introducing a solid-liquid reversible lubricating phase into the thermal sprayed ceramic coating, heating and melting it, and then penetrating it into the inherent pores and micro / nanocracks inside the ceramic coating through a vacuum impregnation process, and then cooling and solidifying it to be retained in the defects, and finally a new type of ceramic-based self-lubricating and highly anti-corrosion composite coating is obtained. However, the method adopted in this patent only improves the influence of coating surface and internal defects on the performance of the ceramic coating. The problem of weak bonding between the coating and the substrate and defects at the interface has not been solved, resulting in rapid failure under high mechanical loads.Patent CN118957479A proposes a metal surface processing method and processing equipment, which uses thermal spraying equipment to thermally spray metal ceramic powder on the surface of a stainless steel substrate to form a ceramic metal coating with excellent wear resistance and corrosion resistance. This patent prepares a protective coating through thermal spraying technology, which improves the corrosion and wear resistance of the metal surface, but this method is a "two-step method", which first uses hot rolling and cold rolling technology to form a stainless steel sheet, and then uses thermal spraying technology to coat the sheet for protection, and cannot achieve integrated rolling of film formation-forming-forming. In particular, the temperature gradient between the sprayed ceramic composite powder and the substrate during thermal spraying is very large (the substrate is at room temperature), resulting in excessive thermal stress between the coating and the substrate, and the low-temperature solid substrate cannot undergo high-temperature metallurgical reaction or element diffusion with the coating material, and the interface bonding force of the coating finally formed is very weak, and it is easy to peel off and fail under strong mechanical force.

[0005] Hot rolling in-situ film-forming technology is a new type of ceramic coating preparation method developed in recent years. It uses the high temperature of hot-rolled steel plates to achieve a high-temperature in-situ metallurgical reaction layer film between ceramic composite powders and metal elements on the surface of the plate. At the same time, with the help of the high contact stress generated by hot rolling, the pores inside the coating are reduced or even eliminated, and the coating is flattened. For example, patent CN202410336172.X discloses a hot rolling system and method for in-situ film formation of a corrosion-resistant and wear-resistant ceramic layer on the surface of a steel plate. The ceramic composite powder slurry is evenly spread on the steel plate through a non-woven fabric. The high temperature and high pressure during hot rolling promote the diffusion of elements between the ceramic composite powder and the steel plate, realizing the in-situ film formation of the ceramic layer on the surface of the steel plate, and enhancing the interface bonding strength between the modified layer and the substrate. However, the hot rolling temperature of this patent is between 900 and 1200°C. With the natural cooling of the steel plate in the air environment and the heat transfer of the ceramic composite powder slurry, the temperature of the reaction between the ceramic composite powder and the metal elements is lower than 1000°C, which is much lower than the melting temperature of the ceramic composite powder raw materials (SiO2 melting point 1710°C, Al2O3 melting point 2050°C, ZnO melting point 1975°C, MgO melting point 2852°C). As a result, only element diffusion reaction can occur between the ceramic composite powders, and melting and recrystallization cannot occur. Therefore, the chemical reaction between the ceramic powders is insufficient, and the formed ceramic layer has large grain boundary defects and weak bonding force, which ultimately leads to relatively weak wear resistance. In view of this, the patent (application number 2024114106556) invented a laser-hot rolling composite in-situ film-forming system and method for a strong wear-resistant ceramic coating on a metal plate. With the help of the high-temperature melting effect of the laser, the melting recrystallization of the ceramic composite powder and the high-temperature metallurgical reaction with the metal elements on the surface of the plate are accelerated, and a ceramic layer is formed in situ to improve the wear resistance of the metal plate. The characteristic of this patent is that the ceramic composite powder, rather than the ceramic melt, is sprayed onto the surface of a high-temperature steel plate at 800 to 1200°C for preheating, and then with the help of the heating effect of a high-energy laser, the ceramic powder is melted to form a molten pool, and finally a ceramic coating is formed by rolling with a roller. However, the use of Al2O3 or TiO2 powder with high hardness and ultra-high melting point (melting point greater than 1500°C) to prepare a ceramic coating requires the use of a high-power laser for heating treatment, which will directly cause the surface material of the metal matrix to melt and form a metal molten pool. Although the ceramic and metal mixed molten pool is conducive to the formation of metal-ceramic composite coatings, during the rolling process, the liquid metal will splash, overflow or be adsorbed and solidified on the surface of the roller, which will eventually affect the rolling accuracy, surface quality and service performance of the product. Therefore, the patent requires the use of amorphous glass powder without a fixed melting point as the matrix phase of the coating, and the addition of a certain amount of flux to control the melting point of the powder to 1000°C or even lower, such as SiO2-B2O3-Al2O3 glass ceramic powder with a melting point of about 1000°C, to prevent the high melting point from causing high-power laser energy to melt the metal matrix.In addition, the hardness of the amorphous glass phase is much lower than that of crystalline ceramics. For example, the hardness of SiO2 is 7 to 9 GPa, while the hardness of Al2O3 is as high as 20 to 25 GPa. Although Al2O3 in the SiO2-B2O3-Al2O3 system can improve the hardness of the glass matrix phase to a certain extent, the low forming temperature causes the Al2O3 particles to be dispersed in the glass phase instead of forming a molten eutectic structure, resulting in the wear resistance of the actual SiO2-B2O3-Al2O3 glass-ceramic coating being much lower than that of the pure Al2O3 ceramic coating. Obviously, this patent cannot use the high-hardness and high-melting-point Al2O3-TiO2 composite powder with excellent chemical compatibility with titanium alloys to form an in-situ film by ultra-high temperature hot rolling to prepare a pure ceramic coating with strong wear resistance in ultra-high temperature extreme service environments. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a plasma thermal spraying-hot rolling in-situ forming system and method for ultra-high temperature wear-resistant ceramic coatings on titanium alloys, so as to solve the problems of cracks, holes and unevenness in the preparation of ceramic coatings by the current laser cladding method, the problem of weak interface bonding between the substrate and the coating and easy residual pores inside the coating when the coating is prepared by the thermal spraying method, and the problem that the laser-hot rolling composite method cannot prepare ultra-high temperature wear-resistant ceramic coatings.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides a plasma thermal spraying-hot rolling in-situ forming system for ultra-high temperature wear-resistant ceramic coating of titanium alloy, comprising a heating unit, a plasma thermal spraying unit and a hot rolling unit; the heating unit comprises an electromagnetic induction heating device and a conveying roller, the titanium alloy is placed on the conveying roller and heated by the electromagnetic induction heating device, and the conveying roller conveys the heated titanium alloy to the plasma thermal spraying unit;

[0009] The plasma thermal spraying unit package sprays the ceramic composite powder in the powder feeder onto the titanium alloy surface after being subjected to plasma ultra-high temperature heating treatment;

[0010] The hot rolling unit comprises two rollers rotating at the same speed and in different directions. The conveying roller delivers the sprayed titanium alloy to the hot rolling unit for in-situ film-forming and forming rolling.

[0011] The plasma thermal spraying-hot rolling in-situ forming system of the titanium alloy ultra-high temperature wear-resistant ceramic coating proposed in the present invention reduces the temperature gradient between the ceramic composite melt and the substrate during thermal spraying, reduces thermal stress, inhibits microcracks between the substrate and the coating and inside the coating, accelerates the recrystallization of the ceramic composite melt and the high-temperature metallurgical reaction with the metal elements on the surface of the titanium alloy, improves the bonding strength of the interface between the ceramic powder and the titanium alloy, forms an ultra-high temperature ceramic layer in situ, and simultaneously utilizes the high stress forming characteristics of the rolling roller to inhibit microcracks and hole defects in the ceramic coating, ultimately obtaining a uniform, dense, hole-free and crack-free ultra-high temperature wear-resistant ceramic coating, thereby enhancing the ultra-high temperature mechanical properties and wear resistance of the titanium alloy.

[0012] As a further technical solution, the electromagnetic induction heating unit can achieve a heating temperature of up to 2000°C and can achieve heating under an inert gas atmosphere. By using the preheating and heat preservation effect of the high-temperature titanium alloy, the temperature gradient between the ceramic composite melt and the substrate during thermal spraying is reduced, thereby reducing thermal stress and inhibiting microcracks between the substrate and the coating and within the coating.

[0013] As a further technical solution, the composite ceramic powder in the powder feeder of the plasma thermal spraying unit includes 80 to 100 parts of TiO2 and 10 to 20 parts of Al2O3.

[0014] As a further technical solution, the particle size of the TiO2 and Al2O3 powders is 1 to 3 μm.

[0015] As a further technical solution, the high-temperature plasma heating temperature of the plasma thermal spraying unit can reach up to 4500°C, the powder feeding rate is 5-10g / min, the spraying distance is 100-180mm, and the spray gun moving speed is 100-280mm / s; by setting these parameters, the ultra-high temperature ceramic composite powder can be melted and sprayed on the surface of the titanium alloy at high speed, promoting the recrystallization of the ceramic composite melt and the high-temperature metallurgical reaction with the metal elements on the surface of the titanium alloy, improving the bonding strength of the ceramic coating and the titanium alloy interface, forming an ultra-high temperature ceramic layer in situ, and will not cause the metal matrix to melt.

[0016] As a further technical solution, the rolling rate of the hot rolling unit is 50-150 mm / min, the reduction is 10%-15% of the plate thickness before rolling, and the start rolling temperature is 900-1200°C; by setting these parameters, the high contact stress forming characteristics of the hot rolling unit can be used to suppress microcracks and hole defects in the ceramic coating, and obtain a uniform, dense, hole-free and crack-free high-wear-resistant ceramic coating, ultimately improving the ultra-high temperature mechanical properties and wear resistance of the titanium alloy.

[0017] In a second aspect, the present invention further proposes a method for plasma thermal spraying-hot rolling composite in-situ film formation of ultra-high temperature wear-resistant ceramic coating on titanium alloy surface by using the plasma thermal spraying-hot rolling in-situ forming system of the ultra-high temperature wear-resistant ceramic coating of titanium alloy, comprising the following steps:

[0018] S1. The TiO2 and Al2O3 powders are mixed uniformly to obtain a ceramic composite powder;

[0019] S2. The prepared ceramic composite powder is placed in a powder feeder of a plasma thermal spraying unit;

[0020] S3. Surface pretreatment of the titanium alloy to be rolled, including removal of the oxide layer and cleaning of oil stains;

[0021] S4. Set the heating parameters of the electromagnetic induction heating device, and use the electromagnetic induction heating device to heat the titanium alloy processed in S3 to ensure that the temperature of the titanium alloy meets the rolling temperature during rolling;

[0022] S5. Setting the working parameters of the plasma thermal spraying device, using the conveying roller to convey the heated titanium alloy in S4 to the plasma thermal spraying unit, ensuring that the ceramic composite powder is fully melted and evenly sprayed onto the surface of the high-temperature titanium alloy;

[0023] S6. Setting rolling parameters, including rolling rate and reduction parameters, to ensure uniform film formation of the ceramic layer, while the rolling pressure can effectively reduce the formation of microcracks and pores;

[0024] S7. Start the electromagnetic induction heating unit, plasma thermal spraying unit and hot rolling unit to heat the titanium alloy to the rolling temperature. Use the plasma thermal spraying device to melt the evenly mixed ceramic composite powder at high temperature and quickly spray it onto the surface of the titanium alloy, accelerate the high-temperature metallurgical reaction between the ceramic composite melt and the metal elements on the surface of the titanium alloy, and form a ceramic coating in situ. Finally, use the high-stress forming characteristics of the rolling roller to suppress microcracks and pore defects in the ceramic coating, and obtain a uniform, dense, hole-free and crack-free ultra-high temperature wear-resistant ceramic coating, thereby ultimately improving the wear resistance of the titanium alloy.

[0025] As a further technical solution, the specific process of S1 is as follows: weigh 80 to 100 parts of TiO2 and 10 to 20 parts of Al2O3 powder, put them into the powder mixing chamber of the three-dimensional vibration powder mixer, set the powder mixing time to 120 to 240 min, the powder mixing speed to 80 to 150 rad / min, and the ball-to-material mass ratio to 6:1, start the powder mixer, and after the powder mixing is completed, obtain the ceramic composite powder, which is put into the powder feeder of the S2 plasma thermal spraying unit;

[0026] As a further technical solution, the wear resistance of the titanium alloy obtained in step S7 can be calculated by the Archard wear model, wear volume V = KPL / H, where V is the wear volume, characterizing the wear resistance of the material, K is the wear coefficient, P is the normal load, L is the sliding distance, and H is the hardness of the ceramic coating on the surface of the titanium alloy.

[0027] The beneficial effects of the present invention are as follows:

[0028] Compared with the existing laser cladding technology, thermal spraying technology and laser-hot rolling composite technology, the plasma thermal spraying-hot rolling in-situ forming system and method of the ultra-high temperature wear-resistant ceramic coating of titanium alloy disclosed by the present invention can realize the in-situ film formation of the ultra-high temperature wear-resistant ceramic layer on the surface of titanium alloy. First, the titanium alloy is heated by an electromagnetic induction heating device, and the temperature gradient between the ceramic composite melt and the substrate during thermal spraying is reduced by means of the preheating and heat preservation effect of the high-temperature titanium alloy, thereby reducing the thermal stress and inhibiting the microcracks between the substrate and the coating and inside the coating. At the same time, the high-temperature plasma thermal spraying unit can melt the ultra-high temperature ceramic composite powder and spray it on the surface of the titanium alloy at a high speed, promoting the recrystallization of the ceramic composite melt and the high-temperature metallurgical reaction with the metal elements on the surface of the titanium alloy, improving the bonding strength of the interface between the ceramic coating and the titanium alloy, forming an ultra-high temperature ceramic layer in situ, and will not cause the metal substrate to melt. Finally, by taking advantage of the high contact stress forming characteristics of the hot rolling unit, the microcracks and hole defects of the ceramic coating are suppressed, and a uniform, dense, hole-free and crack-free high wear-resistant ceramic coating is obtained, which ultimately improves the ultra-high temperature mechanical properties and wear resistance of the titanium alloy. That is, the present invention uses the mutual coordination and interaction of the electromagnetic induction heating unit, the plasma thermal spraying unit, and the hot rolling unit to ultimately improve the mechanical properties and tribological properties of the titanium alloy in the ultra-high temperature service environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0030] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0031] Figure 2 is a heating state diagram of the heating unit of the present invention;

[0032] Figure 3 is a spraying schematic diagram of a plasma thermal spraying unit of the present invention;

[0033] Figure 4 is a hot rolling state diagram of a hot rolling unit of the present invention;

[0034] Among them, 1-heating unit, 2-plasma thermal spraying unit, 3-hot rolling unit, 4-titanium alloy plate, 11-electromagnetic induction heater, 12-magnetic induction heating coil, 13-conveyor roller, 21-plasma thermal spraying device, 22-powder feeder, 23-air compressor, 24-ceramic composite melt, 31-roller, 32-ultra-high temperature ceramic coating. DETAILED DESCRIPTION

[0035] As described in the background technology, laser cladding technology, plasma thermal spraying technology and laser-hot rolling composite technology are commonly used to prepare wear-resistant ceramic coatings on the surfaces of various metal plates. However, the ceramic coating prepared by laser cladding technology has problems such as microcracks, hole defects and uneven coating. The interface bonding force between the ceramic coating prepared by plasma thermal spraying technology and the substrate is relatively weak, and the temperature difference between the substrate and the ceramic melt is large, resulting in cracks. The laser-hot rolling composite technology cannot prepare ultra-high temperature wear-resistant ceramic coatings. In order to solve the above problems, the present invention proposes a plasma thermal spraying-hot rolling in-situ forming system and method for ultra-high temperature wear-resistant ceramic coatings of titanium alloys. First, the titanium alloy is heated to the rolling temperature by means of an electromagnetic induction heating device. Subsequently, the high-temperature plasma in the plasma thermal spraying unit is used to heat the high-melting-point ceramic composite powder to a molten state, and it is sprayed on the surface of the high-temperature titanium alloy at a high speed, reducing the temperature difference between the ceramic melt and the titanium alloy, promoting the recrystallization of the ceramic composite melt and the high-temperature metallurgical reaction with the metal elements on the surface of the titanium alloy, forming a ceramic coating in situ, and improving the bonding strength of the ceramic coating and the titanium alloy interface. Finally, the high contact stress forming characteristics of the rolling roller are utilized to suppress the microcracks and hole defects in the ceramic coating, and a uniform, dense, hole-free and crack-free ultra-high temperature wear-resistant ceramic coating is obtained, ultimately improving the mechanical properties and tribological properties of the titanium alloy in the ultra-high temperature service environment.

[0036] The present embodiment provides a plasma thermal spraying-hot rolling in-situ forming system for ultra-high temperature wear-resistant ceramic coating of titanium alloy, including a heating unit, a plasma thermal spraying unit and a hot rolling unit; the heating unit includes an electromagnetic induction heating device and a conveying roller, the titanium alloy is placed on the conveying roller, heated by the electromagnetic induction heating device, and the conveying roller delivers the heated titanium alloy to the plasma thermal spraying unit. The plasma thermal spraying unit includes a control cabinet, gas, power cabinet, air compressor, heat exchanger, powder feeder and plasma gun. The plasma spraying unit sprays the ceramic composite powder in the powder feeder onto the surface of the titanium alloy after ultra-high temperature heating treatment by high-temperature plasma. The hot rolling unit includes two rollers rotating at the same speed and in opposite directions, and the conveying roller delivers the sprayed titanium alloy to the hot rolling unit for in-situ film-forming forming and forming.

[0037] The plasma thermal spraying-hot rolling in-situ forming system of the ultra-high temperature wear-resistant ceramic coating of titanium alloy proposed in this embodiment reduces the temperature difference between the ceramic composite melt and the titanium alloy during plasma thermal spraying, reduces thermal stress, and inhibits the formation of microcracks between the substrate and the coating and inside the coating by means of the preheating and heat preservation effect of the high-temperature titanium alloy. In particular, through the melting effect of plasma thermal spraying, the melting recrystallization of the ceramic composite powder and the high-temperature metallurgical reaction with the surface elements of the titanium alloy plate are accelerated, the interface bonding strength between the ceramic layer and the titanium alloy is improved, and the ceramic layer is formed in situ. At the same time, the high stress forming characteristics of the roller are utilized to suppress the microcracks and hole defects of the ceramic coating, and finally a uniform, dense, hole-free and crack-free ultra-high temperature wear-resistant ceramic coating is obtained, which enhances the ultra-high temperature wear resistance of the titanium alloy material.

[0038] like Figure 1 As shown, the plasma thermal spraying-hot rolling in-situ forming system of the titanium alloy ultra-high temperature wear-resistant ceramic coating proposed in this embodiment includes a heating unit 1, a plasma thermal spraying unit 2 and a hot rolling unit 3, as follows:

[0039] like Figure 2 As shown, the heating unit 1 includes an electromagnetic induction heater 11, a magnetic induction heating coil 12 and a conveying roller 13. The titanium alloy 4 is placed on the conveying roller 13 and heated by the magnetic induction heating coil 12. The heating temperature of the electromagnetic induction heater 11 can reach up to 2000°C. The conveying roller 13 can transport the high-temperature titanium alloy 4 in the magnetic induction heating coil 12 to the plasma thermal spraying unit 2. The diameter of the conveying roller 13 is 50 mm.

[0040] like Figure 3 As shown, the plasma thermal spraying unit 2 includes a plasma thermal spraying device 21, a powder feeder 22, and an air compressor 23. The high-temperature titanium alloy 4 is delivered to the plasma thermal spraying unit 2 through a conveying roller 13. The powder feeder 22 can store and provide ceramic composite powder. The air compressor 23 can deliver compressed air to spray the ceramic composite melt onto the surface of the high-temperature titanium alloy 4, and form a ceramic composite melt 24 in situ at high temperature. The high-temperature titanium alloy 4 covered with the ceramic composite melt is delivered to the hot rolling unit 3 through the conveying roller 13;

[0041] like Figure 4 As shown, the hot rolling unit 3 includes two rollers 31 rotating at the same speed and in different directions. The conveying roller 13 delivers the high-temperature titanium alloy 4 covered with a ceramic molten layer to the hot rolling unit 3. The high-temperature titanium alloy 4 covered with a molten layer passes between the two rollers. The high contact stress forming characteristics of the roller 31 are utilized to suppress the generation of microcracks and pore defects in the ceramic coating, and finally a high-hardness ultra-high temperature ceramic coating 32 is obtained.

[0042] The plasma thermal spraying-hot rolling in-situ forming system of the ultra-high temperature wear-resistant ceramic coating of titanium alloy proposed in the present invention reduces the temperature difference between the ceramic composite melt and the titanium alloy during plasma thermal spraying by means of the heating effect of the electromagnetic induction heating device 1 on the titanium alloy, reduces the thermal stress, and inhibits the formation of microcracks between the substrate and the coating and inside the coating. Through the melting effect of plasma thermal spraying, the melting recrystallization of the ceramic composite powder and the high-temperature metallurgical reaction with the surface elements of the titanium alloy plate are accelerated, the interface bonding strength between the ceramic layer and the titanium alloy plate is improved, and the ceramic layer is formed in situ. At the same time, the high stress forming characteristics of the roller are utilized to inhibit the microcracks and hole defects of the ceramic coating, and finally a uniform, dense, hole-free and crack-free ultra-high temperature wear-resistant ceramic coating is obtained, which enhances the ultra-high temperature wear resistance of the titanium alloy material.

[0043] As a further technical solution, the heating temperature of the electromagnetic induction heating unit can reach up to 2000° C., and heating can be achieved under an inert gas atmosphere.

[0044] As a further technical solution, the composite ceramic powder in the powder feeder of the plasma thermal spraying unit includes 80 to 100 parts of TiO2 and 10 to 20 parts of Al2O3.

[0045] As a further technical solution, the particle size of the TiO2 and Al2O3 powders is 1 to 3 μm.

[0046] As a further technical solution, the high-temperature plasma heating temperature of the plasma thermal spraying unit can reach up to 4500°C, the powder feeding rate is 5-10g / min, the spraying distance is 100-180mm, and the spray gun moving speed is 100-280mm / s; by setting these parameters, the ultra-high temperature ceramic composite powder can be melted and sprayed on the surface of the titanium alloy at high speed, promoting the recrystallization of the ceramic composite melt and the high-temperature metallurgical reaction with the metal elements on the surface of the titanium alloy, improving the bonding strength of the ceramic coating and the titanium alloy interface, forming an ultra-high temperature ceramic layer in situ, and will not cause the metal matrix to melt.

[0047] As a further technical solution, the rolling rate of the hot rolling unit is 50-150 mm / min, the reduction is 10%-15% of the plate thickness before rolling, and the starting rolling temperature is 900-1200°C. By setting these parameters, the high contact stress forming characteristics of the hot rolling unit can be used to suppress microcracks and hole defects in the ceramic coating, and obtain a uniform, dense, hole-free and crack-free high-wear-resistant ceramic coating, ultimately improving the ultra-high temperature mechanical properties and wear resistance of the titanium alloy.

[0048] The processing method corresponding to the laser-hot rolling composite in-situ film forming system of the titanium alloy ultra-high temperature wear-resistant ceramic coating comprises the following steps:

[0049] Step 1: Use a three-dimensional vibration powder mixer to mix TiO2 and Al2O3 powders evenly to obtain ceramic composite powder. The specific process is as follows: weigh 80-100 parts of TiO2 and 10-20 parts of Al2O3 powder raw materials, put them into the mixing chamber of the three-dimensional vibration powder mixer, set the mixing time to 120-240min, the mixing speed to 80-150rad / min, and the ball-to-material mass ratio to 6:1.

[0050] Step 2: placing the prepared ceramic composite powder into a powder feeder of a plasma thermal spraying unit;

[0051] Step 3: Surface pretreatment of the titanium alloy to be rolled, including removal of the oxide layer and cleaning of oil stains;

[0052] Step 4: setting heating parameters of the electromagnetic induction heating device, using the electromagnetic induction heating device to heat the titanium alloy processed in S3, and ensuring that the temperature of the metal sheet during rolling meets the rolling start temperature;

[0053] Step 5: Set the plasma thermal spraying working parameters, including high temperature plasma heating temperature of 2000-2500°C, powder feeding rate of 5-10 g / min, spraying distance of 100-180 mm, and spray gun moving speed of 100-280 mm / s.

[0054] Step 6: Set rolling parameters, including rolling rate and reduction parameters, to ensure uniform film formation of the ceramic layer, and that the rolling pressure can effectively reduce the formation of microcracks and pores. The specific process is as follows: the rolling rate is 50-150 mm / min, the reduction is 10%-15% of the thickness of the plate before rolling, and the rolling temperature is 900-1200°C.

[0055] Step 7: Start the heating unit, plasma thermal spraying unit and hot rolling unit, heat the titanium alloy to the rolling temperature, and reduce the temperature difference between the ceramic composite melt and the titanium alloy during plasma thermal spraying by means of the heating effect of the electromagnetic induction heating device, improve the interface bonding strength between the ceramic layer and the titanium alloy, and inhibit the formation of microcracks between the substrate and the coating and inside the coating. Through the melting effect of high-temperature plasma thermal spraying, the melting recrystallization of the high-melting-point ceramic composite powder and the high-temperature metallurgical reaction with the surface elements of the titanium alloy plate are accelerated to form a ceramic layer in situ. At the same time, the high contact stress forming characteristics of the roller are used to inhibit the microcracks and hole defects of the ceramic coating, and finally obtain a uniform, dense, hole-free and crack-free ultra-high temperature wear-resistant ceramic coating, which enhances the wear resistance of the titanium alloy material in the extreme service environment. This embodiment uses the mutual coordination and interaction of the electromagnetic induction heating unit, the plasma thermal spraying unit, and the hot rolling unit; and finally improves the mechanical properties and tribological properties of the titanium alloy in the ultra-high temperature service environment.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A plasma thermal spraying-hot rolling in-situ forming system for ultra-high temperature wear-resistant ceramic coating of titanium alloy, characterized in that: Including heating unit, plasma thermal spraying unit and hot rolling unit, The heating unit comprises an electromagnetic induction heating device and a conveying roller. The titanium alloy is placed on the conveying roller and heated by the electromagnetic induction heating device. The conveying roller conveys the heated titanium alloy to the plasma thermal spraying unit. The plasma thermal spraying unit heats and melts the ceramic composite powder in the powder feeder at ultra-high temperature by plasma and then sprays it onto the surface of the titanium alloy. The hot rolling unit comprises two rollers rotating at the same speed and in different directions. The conveying roller delivers the sprayed titanium alloy to the hot rolling unit for in-situ film-forming and forming rolling.

2. The plasma thermal spraying-hot rolling in-situ forming system of a titanium alloy ultra-high temperature wear-resistant ceramic coating as claimed in claim 1, characterized in that: The electromagnetic induction heating unit can achieve a heating temperature of up to 2000° C., and can achieve heating under an inert gas atmosphere.

3. The plasma thermal spraying-hot rolling in-situ forming system of a titanium alloy ultra-high temperature wear-resistant ceramic coating as claimed in claim 1, characterized in that: The plasma thermal spraying unit comprises a powder feeder, in which ceramic composite powder is added, and the ceramic composite powder comprises 80 to 100 parts of TiO2 and 10 to 20 parts of Al2O3.

4. The plasma thermal spraying-hot rolling in-situ forming system of a titanium alloy ultra-high temperature wear-resistant ceramic coating as claimed in claim 3, characterized in that: The particle size of the TiO2 and Al2O3 powders is between 1 and 3 μm.

5. The plasma thermal spraying-hot rolling in-situ forming system of a titanium alloy ultra-high temperature wear-resistant ceramic coating as claimed in claim 1, characterized in that: The high-temperature plasma heating temperature of the plasma thermal spraying unit can reach up to 4500°C, the powder feeding rate is 5-10g / min, the spraying distance is 100-180mm, and the spray gun moving speed is 100-280mm / s.

6. The plasma thermal spraying-hot rolling in-situ forming system of a titanium alloy ultra-high temperature wear-resistant ceramic coating as claimed in claim 1, characterized in that: The rolling rate of the hot rolling unit is 50-150 mm / min, the reduction is 10%-15% of the plate thickness before rolling, and the starting rolling temperature is 900-1200°C.

7. A plasma thermal spraying-hot rolling in-situ forming method for ultra-high temperature ceramic coating on titanium alloy surface using the plasma thermal spraying-hot rolling in-situ forming system for ultra-high temperature wear-resistant ceramic coating on titanium alloy according to any one of claims 1 to 6, characterized in that: The steps include: S1. The TiO2 and Al2O3 powders are mixed uniformly to obtain a ceramic composite powder; S2. The prepared ceramic composite powder is placed in the powder feeder of the plasma thermal spraying unit; S3. Surface pretreatment of the rolled titanium alloy; S4. Set the heating parameters of the electromagnetic induction heating device, and use the electromagnetic induction heating device to heat the titanium alloy processed in S3 to ensure that the temperature of the titanium alloy meets the rolling temperature during rolling; S5. Setting the working parameters of the plasma thermal spraying device, using the conveying roller to convey the heated titanium alloy in S4 to the plasma thermal spraying unit, ensuring that the high melting point ceramic composite powder is fully melted and evenly sprayed onto the surface of the high temperature titanium alloy; S6. Setting rolling parameters, including rolling rate and reduction parameters, to ensure uniform film formation of the ceramic layer, while the rolling pressure can effectively reduce the formation of microcracks and pores inside the coating; S7. Start the electromagnetic induction heating unit, plasma thermal spraying unit and hot rolling unit to heat the titanium alloy to the rolling temperature. Use the plasma thermal spraying device to melt the evenly mixed ceramic composite powder at high temperature and quickly spray it onto the surface of the titanium alloy, accelerate the high-temperature metallurgical reaction between the ceramic composite melt and the metal elements on the surface of the titanium alloy, and form a ceramic coating in situ. Finally, use the high-stress forming characteristics of the rolling roller to suppress microcracks and pore defects in the ceramic coating, and obtain a uniform, dense, hole-free and crack-free ultra-high temperature wear-resistant ceramic coating, thereby ultimately improving the wear resistance of the titanium alloy.

8. The plasma thermal spraying-hot rolling in-situ forming method of the titanium alloy ultra-high temperature wear-resistant ceramic coating according to claim 7, characterized in that: The specific process of S1 is as follows: weigh 80 to 100 parts of TiO2 and 10 to 20 parts of Al2O3 powder, put them into the powder mixing chamber of the three-dimensional vibration powder mixer, set the powder mixing time to 120 to 240 minutes, the powder mixing speed to 80 to 150 rad / min, and the ball-to-material mass ratio to 6:1, start the powder mixer, and after the powder mixing is completed, obtain the ceramic composite powder, which is put into the powder feeder of the S2 plasma thermal spraying unit.

9. The plasma thermal spraying-hot rolling in-situ forming method of the titanium alloy ultra-high temperature wear-resistant ceramic coating according to claim 7, characterized in that: The wear resistance of the titanium alloy obtained in S7 can be calculated by the Archard wear model: wear volume V = KPL / H, where V is the wear volume, which characterizes the wear resistance of the material, K is the wear coefficient, P is the normal load, L is the sliding distance, and H is the hardness of the ceramic coating on the titanium alloy surface.

10. The plasma thermal spraying-hot rolling in-situ forming method of titanium alloy ultra-high temperature wear-resistant ceramic coating according to claim 7, characterized in that: In S3, the surface pretreatment of the titanium alloy to be rolled includes the removal of the oxide layer and the cleaning of the oil stains.

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