Laser-hot rolling composite in-situ film forming system and method for high-wear-resistance ceramic coating of metal plate

Abstract

The invention relates to a laser-hot rolling composite in-situ film forming system and method for a high-wear-resistance ceramic coating of a metal plate. The laser-hot rolling composite in-situ film forming system comprises a heating unit, a powder spraying unit, a laser cladding unit and a hot rolling unit. After being heated by the heating furnace, the metal plate is conveyed to the powder spraying unit; the ceramic composite powder uniformly and flatly covers the high-temperature metal plate through the powder spraying unit, and then the ceramic composite powder and the plate are conveyed to the laser cladding unit together; and the ceramic composite powder forms a molten layer after being subjected to laser action, and finally the molten layer and the plate are conveyed to a hot rolling unit together for in-situ film forming and molding rolling. By the adoption of the laser-hot rolling composite system, by means of the preheating effect of a high-temperature metal plate and the melting effect of laser, the high-temperature metallurgical reaction of ceramic composite powder and metal elements can be accelerated, a ceramic layer is formed in situ, meanwhile, the high-wear-resistance ceramic coating which is uniform, compact, free of holes and cracks is obtained by means of the high-stress forming characteristic of a roller, and the service life of the coating is prolonged. And finally, the wear resistance of the metal plate is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of metal material forming properties, and in particular to a laser-hot rolling composite in-situ film forming system and method for a strong wear-resistant ceramic coating on a metal plate. Background Art

[0002] With the continuous development of modern industry, the service environment of advanced metal material parts such as titanium alloy, stainless steel and high-temperature alloy is becoming more and more harsh, and high-frequency heavy-load contact friction will cause rapid wear on the surface of advanced metal material parts, which will shorten the product life and cause huge economic losses. The hardness of ceramic materials is much higher than that of metal materials. Therefore, they can better resist the deformation failure of materials induced by external loads during contact friction and show excellent wear resistance. In recent years, the use of ceramic powders to modify metal surface materials is an effective means to improve the wear resistance of materials, and has become a research hotspot in the field of metal material forming technology.

[0003] At present, the laser cladding method is widely used to prepare wear-resistant ceramic coatings on the surface of metal plates in situ. The metal matrix and ceramic composite powder are melted simultaneously by the rapid heating effect of the high-power laser beam to form a metallurgical bonding layer of ceramic and metal, thereby improving the wear resistance of the product. However, the temperature gradient effect of rapid heating and cooling during laser cladding can cause microcracks between the matrix and the coating and inside the coating. At the same time, when the ceramic powder is rapidly melted, the residual gas between the powders cannot be quickly discharged, which leads to residual pores in the coating, and ultimately affects the mechanical properties of the coating. In addition, during the laser cladding process, the molten layer of the ceramic powder is naturally cooled and formed, resulting in uneven coating thickness. Therefore, the process of preparing ceramic coatings by laser cladding needs further research and improvement. Patent CN116479417A proposes a method for preparing a composite coating by high-speed laser cladding of pure ceramic powder. By adjusting the laser parameters to control the dilution degree of the matrix material, a metal-ceramic composite coating with a continuous gradient structure is formed, which reduces the property difference between the matrix material and the ceramic coating and inhibits the cracking of the coating. However, this patent is still a "pressureless" film-forming technology that relies on a single laser high temperature, so the problems of porosity and uneven thickness in the coating cannot be eliminated, resulting in relatively poor wear resistance of the product. Patent CN115747789A proposes a device and method for preparing a crack-resistant laser cladding coating, which forms a reticulated layer by electroplating pretreatment on the surface of the substrate, reduces the property difference between the substrate and the coating, and adds a heating chamber to reduce the thermal stress during laser cladding, thereby inhibiting the cracking of the coating. However, this patent does not have an external load or force in the process of preparing the ceramic coating, and the molten layer of the ceramic powder is still formed by natural cooling, resulting in a large number of pores in the coating and uneven coating thickness. In addition, the electroplating pretreatment process increases the preparation cost of the coating.

[0004] 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. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a laser-hot rolling composite in-situ film forming system and method for a highly wear-resistant ceramic coating on a metal plate, so as to solve the problems of cracks, holes and unevenness in the current laser cladding preparation of ceramic coatings, and at the same time improve the problem of insufficient melting and recrystallization of ceramic composite powders in the hot rolling in-situ preparation of ceramic coatings.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a laser-hot rolling composite in-situ film forming system for a strong wear-resistant ceramic coating on a metal plate, comprising a heating unit, a powder spraying unit, a laser cladding unit and a hot rolling unit arranged in sequence; the heating unit comprises a heating furnace and a conveying roller, the metal plate is placed on the conveying roller, and is heated by the heating furnace to obtain a high-temperature metal plate; the conveying roller can transport the metal plate out of the heating furnace;

[0008] The powder spraying unit includes a powder bin, a powder spraying device and a scraper. The metal sheet is delivered to the powder spraying unit through a conveying roller. The powder bin can store and provide ceramic composite powder. The powder spraying device sprays the ceramic composite powder onto the high-temperature metal sheet. The scraper evenly covers the accumulated ceramic composite powder onto the high-temperature metal sheet.

[0009] The laser cladding unit includes a gas storage device, an air jet device and a laser. The conveying roller delivers the high-temperature metal plate covered with ceramic composite powder to the laser cladding unit. The gas storage device can store inert gas. The air jet device sprays the inert gas to the laser spot on the metal plate. The laser melts the ceramic composite powder layer covering the high-temperature metal plate to form a molten layer.

[0010] The hot rolling unit includes two rollers rotating at the same speed and in different directions. A conveying roller delivers a high-temperature metal sheet covered with a molten layer to the hot rolling unit for in-situ film-forming and forming rolling. The metal sheet passes between the two rollers.

[0011] The laser-hot rolling composite in-situ film-forming system for highly wear-resistant ceramic coatings on metal plates proposed in the present invention accelerates the melting recrystallization of ceramic composite powders and the high-temperature metallurgical reaction with the metal elements on the surface of the plate by means of the preheating effect of the high-temperature steel plate and the high-temperature melting effect of the laser, and forms a ceramic layer in situ. At the same time, the high-stress forming characteristics of the roller are used to suppress microcracks and hole defects in the ceramic coating, and finally obtain a uniform, dense, hole-free and crack-free highly wear-resistant ceramic coating, thereby enhancing the wear resistance of the metal material. That is, the present invention improves the mechanical properties and tribological properties of advanced metal plates through the mutual coordination and interaction of the heating unit, the powder spraying unit, the laser cladding unit, and the hot rolling unit.

[0012] As a further technical solution, the heating temperature of the heating unit is between 50-1500° C., and heating can be achieved under an inert gas atmosphere.

[0013] As a further technical solution, the composite ceramic powder sprayed out by the powder spraying unit includes 40-60 parts of SiO2, 30-50 parts of B2O3, and 5-15 parts of Al2O3.

[0014] As a further technical solution, the particle size of the SiO2, B2O3 and Al2O3 powders is 1-10 μm.

[0015] As a further technical solution, the powder spraying rate of the powder spraying unit is 5-10 g / min.

[0016] As a further technical solution, the laser spot diameter of the laser cladding unit is 2-5 mm, the power is 1-2 kW, the scanning speed is 40-80 mm / s, and the overlap rate of the laser scanning path is 50%-70%;

[0017] As a further technical solution, the rolling rate of the hot rolling unit is 30-60 mm / min, the reduction is 5%-10% of the plate thickness before rolling, and the starting rolling temperature is 900-1200°C.

[0018] In a second aspect, the present invention further proposes a method for laser-hot rolling composite in-situ film formation of a wear-resistant ceramic coating on the surface of a metal plate using the laser-hot rolling composite in-situ film formation system for the strong wear-resistant ceramic coating on the metal plate, comprising the following steps:

[0019] S1. The SiO2, B2O3 and Al2O3 powders were mixed uniformly using a three-dimensional vibration powder mixer to obtain a ceramic composite powder;

[0020] S2. Place the prepared composite ceramic powder into the powder bin of the powder spraying unit;

[0021] S3. Pre-treating the metal sheet to be rolled by removing the oxide layer and cleaning the oil stains on the surface;

[0022] S4. Set the heating parameters of the heating furnace, put the metal sheet processed in S3 into the heating furnace for heating, and ensure that the temperature of the metal sheet meets the rolling temperature during rolling;

[0023] S5. Setting powder spraying parameters, using a conveying roller to convey the metal sheet heated in S4 to the powder spraying unit, ensuring that the ceramic composite powder can evenly cover the surface of the high-temperature metal sheet;

[0024] S6. Setting laser cladding parameters, including laser power, scanning speed, spot diameter and overlap rate parameters, to ensure that the ceramic composite powder is fully melted before rolling;

[0025] S7. 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;

[0026] S8. Start the heating unit, powder spraying unit, laser cladding unit and hot rolling unit to heat the metal plate to the rolling temperature, and then use the powder spraying unit and laser melting to accelerate the high-temperature metallurgical reaction of the ceramic composite powder and metal elements on the surface of the steel plate to form a ceramic layer in situ. Finally, use the high stress forming characteristics of the rolling roller to suppress the micro cracks and pore defects of the ceramic coating, and obtain a uniform, dense, hole-free and crack-free high wear-resistant ceramic coating, thereby finally improving the wear resistance of advanced metal plates.

[0027] As a further technical solution, the specific process of S1 is as follows: weigh 40-60 parts of SiO2, 30-50 parts of B2O3, and 5-15 parts of Al2O3 powder raw materials, put them into the mixing chamber of the three-dimensional vibration powder mixer, set the mixing rate to 50-100rpm, and the mixing time to 30-60min. After stirring, obtain the ceramic composite powder, which is put into the powder bin of the S2 powder spraying unit.

[0028] As a further technical solution, the specific process of S5 is as follows: the ceramic composite powder is sprayed onto the surface of the high-temperature metal plate at a powder spraying rate of 5-10g / min, and then the composite powder is evenly spread on the surface of the plate using a scraper at a vertical distance of 1-1.5mm from the plate.

[0029] As a further technical solution, the wear resistance of the metal plate obtained in S8 can be calculated by the Archard wear model, and the wear volume V = KPL / H, where V is the wear volume used to characterize 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 metal plate.

[0030] The beneficial effects of the present invention are as follows:

[0031] Compared with the existing laser cladding technology and hot rolling in-situ film forming technology, the laser-hot rolling composite in-situ film forming system and method of ceramic coating disclosed by the present invention can realize the in-situ film forming of strong wear-resistant ceramic layer on the surface of metal plate. First, the high-temperature steel plate is preheated by the heating unit, and the temperature gradient of the ceramic composite powder during laser cladding is reduced by the preheating effect of the high-temperature steel plate, the thermal stress is reduced, and the microcracks between the substrate and the coating and inside the coating are suppressed. At the same time, the laser cladding unit promotes the melting recrystallization of the ceramic composite powder and the high-temperature metallurgical reaction with the metal elements on the surface of the steel plate through the high-temperature melting effect of the laser, and forms a ceramic layer in situ. Finally, the hot rolling unit uses the high-stress forming characteristics of the roller to suppress the microcracks and hole defects of the ceramic coating, and obtains a uniform, dense, hole-free and crack-free high-wear-resistant ceramic coating, and finally improves the mechanical properties and tribological properties of advanced metal plates. That is, the present invention improves the mechanical properties and tribological properties of advanced metal plates through the mutual coordination and interaction of the heating unit, the powder spraying unit, the laser cladding unit, and the hot rolling unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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.

[0033] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0034] Figure 2 is a heating state diagram of the heating unit of the present invention;

[0035] Figure 3 Schematic diagram of powder spraying of the powder spraying unit of the present invention;

[0036] Figure 4 is a laser melting state diagram of the laser cladding unit of the present invention;

[0037] Figure 5 is a hot rolling state diagram of a hot rolling unit of the present invention;

[0038] Figure 6 The cross-sectional SEM micrograph and surface morphology of the ceramic coating on the metal sheet prepared by the laser cladding method; (a) is the cross-sectional SEM micrograph; (b) is the surface morphology;

[0039] Figure 7 Cross-sectional SEM micrograph and surface morphology of the ceramic coating on the metal sheet prepared by the laser-hot rolling composite in-situ film forming method, where (a) is the cross-sectional SEM micrograph of the ceramic coating on the metal sheet; (b) is the surface morphology.

[0040] Among them, 1-heating unit, 2-powder spraying unit, 3-laser cladding unit, 4-hot rolling unit, 5-metal plate, 11-heating furnace, 12-conveyor roller, 21-powder bin, 22-powder spraying device, 23-scraper, 24-ceramic composite powder layer, 31-gas storage device, 32-injection device, 33-laser, 41-roller. DETAILED DESCRIPTION

[0041] As described in the background technology, laser cladding and hot rolling methods are often used to prepare wear-resistant ceramic coatings on the surface of metal plates in situ. However, the ceramic coatings prepared by the above two methods cannot solve the problems of coating cracking, holes, uneven coating or insufficient ceramic melting. In order to solve the above problems, the present invention proposes a laser-hot rolling composite in-situ film forming system and method for strong wear-resistant ceramic coatings on metal plates, which uses the preheating effect of high-temperature steel plates to reduce the temperature gradient of ceramic composite powders during laser cladding, reduce thermal stress, and inhibit microcracks between the substrate and the coating and inside the coating. The high-temperature melting effect of the laser is used to fully melt the ceramic composite powder, accelerate the recrystallization effect between the ceramic composite powders and the high-temperature metallurgical reaction with the metal elements on the surface of the steel plate, and form a high-strength and high-density ceramic layer in situ. Finally, the high-stress forming characteristics of the roller are used to suppress microcracks and hole defects in the ceramic coating, and a uniform, dense, hole-free and crack-free high-wear-resistant ceramic coating is obtained, which ultimately improves the wear resistance of advanced metal plates.

[0042] The present embodiment provides a laser-hot rolling composite in-situ film-forming system for a highly wear-resistant ceramic coating on a metal plate, comprising a heating unit, a powder spraying unit, a laser cladding unit and a hot rolling unit; the heating unit comprises a heating furnace and a conveying roller, the metal plate is placed on the conveying roller, heated by the heating furnace, and the conveying roller conveys the heated metal plate to the powder spraying unit; the powder spraying unit comprises a powder bin, a powder spraying device and a scraper, the powder bin can store and provide ceramic composite powder, the powder spraying device sprays the ceramic composite powder onto the high-temperature metal plate, and the scraper evenly covers the accumulated ceramic composite powder on the high-temperature metal plate; the laser cladding unit comprises a gas storage device, an air jet device and a laser, the conveying roller conveys the high-temperature metal plate covered with the ceramic composite powder to the laser cladding unit, the gas storage device can store inert gas, the air jet device sprays inert gas to the laser spot on the metal plate, and the laser melts the ceramic composite powder layer covering the high-temperature metal plate to form a molten layer. The hot rolling unit includes two rollers rotating at the same speed and in different directions. The conveying roller delivers the high-temperature metal plate and the high-temperature metal plate covered with a molten layer to the hot rolling unit for in-situ film-forming and forming rolling. The metal plate passes between the two rollers.

[0043] The laser-hot rolling composite in-situ film-forming system for high-wear-resistant ceramic coatings on metal materials proposed in this embodiment uses the preheating effect of high-temperature steel plates to reduce the temperature gradient of the ceramic composite powder during laser cladding, reduce thermal stress, and inhibit the formation of microcracks between the substrate and the coating and within the coating. Through the melting effect of the laser, the melting recrystallization of the ceramic composite powder and the high-temperature metallurgical reaction with the surface elements of the metal plate are accelerated to form a ceramic layer in situ. At the same time, the high-stress forming characteristics of the roller are used to suppress microcracks and hole defects in the ceramic coating, and finally a uniform, dense, hole-free and crack-free high-wear-resistant ceramic coating is obtained, thereby enhancing the wear resistance of the metal material.

[0044] like Figure 1 As shown, the laser-hot rolling composite in-situ film-forming system for the strong wear-resistant ceramic coating of the metal plate proposed in this embodiment includes a heating unit 1, a powder spraying unit 2, a laser cladding unit 3 and a hot rolling unit 4 which are arranged in sequence. The heating unit 1 heats the plate to obtain a high-temperature metal plate; the powder spraying unit 2 evenly covers the ceramic composite powder on the high-temperature metal plate; the laser cladding unit 3 melts the ceramic composite powder layer covering the high-temperature metal plate to form a molten layer; the hot rolling unit 4 performs in-situ film-forming forming rolling; the details are as follows:

[0045] like Figure 2As shown, the heating unit 1 includes a heating furnace 11 and a conveying roller 12. The metal sheet 5 is placed on the conveying roller 12 and heated by the heating furnace 11. The heating temperature range of the heating furnace 11 is 50-1500°C, and the temperature of the heated metal sheet can reach 900-1200°C. The conveying roller 12 can transport the high-temperature metal sheet 5 from the heating furnace 11 to the powder spraying unit 2, the laser cladding unit 3 and the hot rolling unit 4 in sequence; the diameter of the conveying roller 12 can be 50mm;

[0046] like Figure 3 As shown, the powder spraying unit 2 includes a powder bin 21, a powder spraying device 22 and a scraper 23. The high-temperature metal sheet 5 is delivered to the powder spraying unit 2 through a conveying roller 12. The powder bin 21 can store and provide ceramic composite powders. The powder spraying device 22 sprays the ceramic composite powders onto the heated metal sheet 5. The scraper 23 is arranged behind the powder spraying device 22 and is used to evenly cover the accumulated ceramic composite powder layer 24 onto the high-temperature metal sheet 5. The high-temperature metal sheet 5 evenly covered with the ceramic composite powder layer is delivered to the laser cladding unit 3 through the conveying roller 12.

[0047] like Figure 4 As shown, the laser cladding unit 3 includes a gas storage device 31, an air jet device 32 and a laser 33. The conveying roller 12 delivers the high-temperature metal plate 5 covered with ceramic composite powder to the laser cladding unit 3. The gas storage device 31 can store inert gas. The air jet device 32 is arranged before the laser 33. The air jet device 32 sprays the inert gas to the laser spot on the high-temperature metal plate 5 to prevent oxidation of the metal matrix and the ceramic composite powder. The laser 33 melts the ceramic composite powder layer covering the high-temperature metal plate 5 to form a molten layer.

[0048] like Figure 5 As shown, the hot rolling unit 4 includes two rollers 41 rotating at the same speed and in different directions. The conveying roller 12 delivers the high-temperature metal sheet 5 covered with a molten layer to the hot rolling unit 4. The high-temperature metal sheet 5 covered with a molten layer passes between the two rollers, and the high-stress forming characteristics of the roller 41 are used to suppress microcracks and pore defects in the ceramic coating.

[0049] The laser-hot rolling composite in-situ film-forming system for highly wear-resistant ceramic coating of metal plates proposed by the present invention preheats the steel plate through the heating unit 1, and uses the preheating effect of the high-temperature steel plate to reduce the temperature gradient of the ceramic composite powder during laser cladding, reduce thermal stress, and inhibit the generation of microcracks between the substrate and the coating and inside the coating. Then, through the laser melting effect of the laser cladding unit 3, the ceramic composite powder is fully melted, the melting recrystallization of the ceramic composite powder on the surface of the steel plate and the high-temperature metallurgical reaction with the metal elements are accelerated, and a ceramic layer is formed in situ. Finally, the high stress forming characteristics of the rollers in the hot rolling unit 4 are utilized to inhibit microcracks and hole defects in the ceramic coating, and a uniform, dense, hole-free and crack-free high-wear-resistant ceramic coating is obtained, which ultimately improves the wear resistance of advanced metal plates.

[0050] As a further technical solution, the heating temperature of the heating unit 1 is between 50-1500° C., and heating can be achieved under an inert gas atmosphere.

[0051] As a further technical solution, the composite ceramic powder sprayed out by the powder spraying unit 2 includes 40-60 parts of SiO2, 30-50 parts of B2O3, and 5-15 parts of Al2O3.

[0052] As a further technical solution, the particle size of the SiO2, B2O3 and Al2O3 powders is 1-10 μm.

[0053] As a further technical solution, the powder spraying rate of the powder spraying unit 2 is 5-10 g / min.

[0054] As a further technical solution, the laser spot diameter of the laser cladding unit 3 is 2-5 mm, the power is 1-2 kW, the scanning speed is 40-80 mm / s, and the overlap rate (spot overlap area) is 50%-70%;

[0055] As a further technical solution, the rolling rate of the hot rolling unit 4 is 30-60 mm / min, the reduction is 5%-10% of the plate thickness before rolling, and the starting rolling temperature is 900-1200°C.

[0056] The processing method corresponding to the laser-hot rolling composite in-situ film forming system for the above-mentioned strong wear-resistant ceramic coating of the metal plate comprises the following steps:

[0057] Step 1: Use a three-dimensional vibration powder mixer to mix SiO2, B2O3 and Al2O3 powders evenly to obtain ceramic composite powder. The specific process is as follows: weigh 40-60 parts of SiO2, 30-50 parts of B2O3, and 5-15 parts of Al2O3 powder raw materials, put them into the mixing chamber of the three-dimensional vibration powder mixer, set the mixing speed to 50-100rpm, the mixing time to 30-60min, and obtain ceramic composite powder after stirring;

[0058] Step 2: Place the prepared composite ceramic powder into the powder bin of the powder spraying unit;

[0059] Step 3: Pre-treat the metal sheet to be rolled by removing the oxide layer and cleaning the oil stains on the surface;

[0060] Step 4: Set the heating parameters of the heating furnace, put the metal sheet processed in S3 into the heating furnace for heating, and ensure that the temperature of the metal sheet meets the rolling start temperature during rolling;

[0061] Step 5: Set the powder spraying parameters and use the conveyor roller to transport the heated metal sheet in S4 to the powder spraying unit to ensure that the ceramic composite powder can evenly cover the surface of the high-temperature metal sheet. The specific process is as follows: the ceramic composite powder is sprayed onto the surface of the high-temperature metal sheet at a powder spraying rate of 5-10g / min, and then the composite powder is evenly spread on the surface of the sheet using a scraper at a vertical distance of 1-1.5mm from the sheet;

[0062] Step 6: Set the laser cladding parameters, including laser power, scanning speed, spot diameter and overlap rate parameters, to ensure that the ceramic composite powder is fully melted before rolling. The specific process is as follows: the laser spot diameter of the laser cladding unit is 2-5mm, the power is 1-2kW, the scanning speed is 40-80mm / s, and the overlap rate (spot overlap area) is 50%-70%;

[0063] Step 7: 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 30-60 mm / min, the reduction is 5%-10% of the plate thickness before rolling, and the start rolling temperature is 900-1200°C;

[0064] Step 8: Start the heating unit, powder spraying unit, laser cladding unit and hot rolling unit, heat the metal sheet to the rolling temperature, and use the preheating effect of the high-temperature metal sheet to reduce the temperature gradient of the ceramic composite powder during laser cladding, reduce thermal stress, and inhibit the generation of microcracks between the substrate and the coating and inside the coating. Through the powder spraying unit and laser melting, the high-temperature metallurgical reaction between the ceramic composite powder and the metal elements on the surface of the steel plate is accelerated to form a ceramic layer in situ. Finally, the high-stress forming characteristics of the roller are used to inhibit microcracks and pore defects in the ceramic coating, and a uniform, dense, hole-free and crack-free high-wear-resistant ceramic coating is obtained, which ultimately improves the wear resistance of advanced metal sheets.

[0065] Comparison of experimental results: Figure 6 As shown in Figure 2, there are holes and cracks at the interface between the ceramic coating prepared by laser cladding and the metal substrate ( Figure 6(a) in the figure), there are also some hole defects on the surface of the ceramic coating ( Figure 6 (b) in the figure). The rapid heating and cooling during the laser cladding process makes it difficult for the gas in the ceramic composite powder to be discharged, thus forming pore defects in the coating. At the same time, the high temperature gradient during the laser cladding process induces cracking of the coating and the substrate. The pores and cracks weaken the bonding strength between the coating and the substrate, weaken the performance of the coating, and reduce the wear resistance of the coating. Figure 7 As shown in Figure 2, there are no obvious holes and cracks in the ceramic coating prepared by the laser-hot rolling composite in-situ film forming method ( Figure 7 (a) in the figure), and the coating surface is flatter ( Figure 7 (b) in the figure). The laser-hot rolling composite in-situ film-forming method reduces the temperature gradient during the laser cladding process by means of the preheating effect of hot rolling, inhibiting the cracking of the coating and the substrate. At the same time, the high contact stress of rolling is used to promote the discharge of residual gas in the ceramic composite powder and make the coating surface flatter. The wear volume formula calculated according to the Archard wear model is V = KPL / H, where V is the wear volume, 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 metal plate. The coating surface prepared by the laser-hot rolling composite in-situ film-forming method is flatter, and the bonding strength between the coating and the substrate is higher, which is beneficial to reduce the wear coefficient and increase the hardness of the ceramic coating on the surface of the metal plate. Therefore, under the same conditions, the coating prepared by the laser-hot rolling composite in-situ film-forming method has a smaller wear volume and better wear resistance.

[0066] Example 1

[0067] Based on the above system, this embodiment provides a method for strengthening stainless steel by laser-hot rolling composite in-situ film formation of ceramic composite powder, which specifically includes the following steps:

[0068] S1. Weigh 45 parts of SiO2, 45 parts of B2O3, and 10 parts of Al2O3 powder raw materials, put them into the mixing chamber of the three-dimensional vibration mixer, set the mixing rate to 80rpm, the mixing time to 60min, and obtain a ceramic composite powder after stirring;

[0069] S2. Place the prepared composite ceramic powder into the powder bin of the powder spraying unit;

[0070] S3. Use 200-grit sandpaper to grind a stainless steel plate with a length of 500 mm, a width of 80 mm, and a thickness of 10 mm, and then ultrasonically clean it in pure water for 20 min to remove the oxide layer and oil stains on the surface of the stainless steel plate;

[0071] S4. Set the heating temperature of the heating furnace to 1100°C, keep the temperature for 30 minutes, put the stainless steel plate processed in S3 into the heating furnace for heating, and ensure that the temperature of the stainless steel plate meets the rolling temperature during rolling;

[0072] S5. Set the powder spraying rate parameter to 7g / min, and use the conveyor roller to convey the heated stainless steel plate in S4 to the powder spraying unit to ensure that the ceramic composite powder can evenly cover the surface of the high-temperature stainless steel plate;

[0073] S6. Setting laser cladding parameters, including laser power of 1.5 kW, scanning speed of 80 mm / s, spot diameter of 2 mm, and overlap rate of 50%, to ensure that the ceramic composite powder is fully melted before rolling;

[0074] S7. Setting rolling parameters, including a rolling rate of 60 mm / min and a reduction of 5%, to ensure uniform film formation of the ceramic layer, while the rolling pressure can effectively reduce the formation of microcracks and pores;

[0075] S8. Start the heating unit, powder spraying unit, laser cladding unit and hot rolling unit, heat the stainless steel plate to 1100°C, and use the preheating effect of the high-temperature stainless steel plate to reduce the temperature gradient during laser cladding, reduce thermal stress, and inhibit the generation of microcracks between the substrate and the coating and inside the coating. Then, through the powder spraying unit and laser melting, accelerate the high-temperature metallurgical reaction of the ceramic composite powder and the metal elements on the surface of the stainless steel to form a ceramic layer in situ. Finally, use the high-stress forming characteristics of the roller to inhibit microcracks and pore defects in the ceramic coating, and obtain a uniform, dense, hole-free and crack-free high-wear-resistant ceramic coating;

[0076] S9. After the processing is completed, the heating unit, the powder spraying unit, the laser cladding unit and the hot rolling unit are turned off.

[0077] Example 2

[0078] Based on the above system, this embodiment provides a method for strengthening titanium alloy by laser-hot rolling composite in-situ film formation of ceramic composite powder, which specifically includes the following steps:

[0079] S1. Weigh 50 parts of SiO2, 35 parts of B2O3, and 15 parts of Al2O3 powder raw materials, put them into the mixing chamber of the three-dimensional vibration mixer, set the mixing rate to 80rpm, the mixing time to 60min, and obtain a ceramic composite powder after stirring;

[0080] S2. Place the prepared composite ceramic powder into the powder bin of the powder spraying unit;

[0081] S3. A titanium alloy plate with a length of 500 mm, a width of 80 mm, and a thickness of 10 mm was polished using 800-grit sandpaper, and then ultrasonically cleaned in pure water for 20 min to remove the oxide layer and oil stains on the surface of the titanium alloy plate;

[0082] S4. Set the heating temperature of the heating furnace to 1000°C, keep the temperature for 30 minutes, put the titanium alloy plate processed in S3 into the heating furnace for heating, and ensure that the temperature of the titanium alloy plate meets the rolling temperature during rolling;

[0083] S5. Set the powder spraying rate parameter to 7g / min, and use the conveyor roller to convey the heated titanium alloy plate in S4 to the powder spraying unit to ensure that the ceramic composite powder can evenly cover the surface of the high-temperature titanium alloy plate;

[0084] S6. Setting laser cladding parameters, including laser power of 1.5 kW, scanning speed of 80 mm / s, spot diameter of 2 mm, and overlap rate of 70%, to ensure that the ceramic composite powder is fully melted before rolling;

[0085] S7. Setting rolling parameters, including rolling rate of 36 mm / min and reduction of 5%, to ensure uniform film formation of the ceramic layer, while the rolling pressure can effectively reduce the formation of microcracks and pores;

[0086] S8. Start the heating unit, powder spraying unit, laser cladding unit and hot rolling unit, heat the titanium alloy plate to 1000°C, and use the preheating effect of the high-temperature titanium alloy plate to reduce the temperature gradient during laser cladding, reduce thermal stress, and inhibit the generation of microcracks between the substrate and the coating and inside the coating. Then, through the powder spraying unit and laser melting, accelerate the high-temperature metallurgical reaction of the ceramic composite powder and the metal elements on the surface of the titanium alloy to form a ceramic layer in situ. Finally, use the high-stress forming characteristics of the roller to suppress the microcracks and pore defects of the ceramic coating, and obtain a uniform, dense, hole-free and crack-free high-wear-resistant ceramic coating;

[0087] S9. After the processing is completed, the heating unit, the powder spraying unit, the laser cladding unit and the hot rolling unit are turned off.

[0088] Example 3

[0089] Based on the above system, this embodiment provides a method for strengthening Inconel718 high temperature alloy by laser-hot rolling composite in-situ film formation of ceramic composite powder, which specifically includes the following steps:

[0090] S1. Weigh 60 parts of SiO2, 30 parts of B2O3, and 10 parts of Al2O3 powder raw materials, put them into the mixing chamber of the three-dimensional vibration mixer, set the mixing rate to 80rpm, the mixing time to 60min, and obtain a ceramic composite powder after stirring;

[0091] S2. Place the prepared composite ceramic powder into the powder bin of the powder spraying unit;

[0092] S3. Use 200-grit sandpaper to grind the Inconel718 high-temperature alloy plate with a length of 500 mm, a width of 80 mm, and a thickness of 10 mm, and then put it into pure water for ultrasonic cleaning for 20 minutes to remove the oxide layer and oil stains on the surface of the Inconel718 high-temperature alloy plate;

[0093] S4. Set the heating temperature of the heating furnace to 1200°C, keep the temperature for 30 minutes, put the Inconel718 high temperature alloy plate processed in S3 into the heating furnace for heating, and ensure that the temperature of the Inconel718 high temperature alloy plate meets the rolling temperature during rolling;

[0094] S5. Set the powder spraying rate parameter to 7g / min, and use the conveyor roller to convey the Inconel718 high-temperature alloy plate heated in S4 to the powder spraying unit to ensure that the ceramic composite powder can evenly cover the surface of the high-temperature Inconel718 high-temperature alloy plate;

[0095] S6. Setting laser cladding parameters, including laser power of 2 kW, scanning speed of 80 mm / s, spot diameter of 2 mm, and overlap rate of 50%, to ensure that the ceramic composite powder is fully melted before rolling;

[0096] S7. Setting rolling parameters, including a rolling rate of 60 mm / min and a reduction of 5%, to ensure uniform film formation of the ceramic layer, while the rolling pressure can effectively reduce the formation of microcracks and pores;

[0097] S8. Start the heating unit, powder spraying unit, laser cladding unit and hot rolling unit, heat the Inconel718 high-temperature alloy plate to 1200°C, and use the preheating effect of the high-temperature Inconel718 high-temperature alloy plate to reduce the temperature gradient during laser cladding, reduce thermal stress, and inhibit the generation of microcracks between the substrate and the coating and inside the coating. Then, through the powder spraying unit and laser melting, accelerate the high-temperature metallurgical reaction of the ceramic composite powder and the metal elements on the surface of the Inconel718 high-temperature alloy plate to form a ceramic layer in situ. Finally, use the high-stress forming characteristics of the roller to suppress the microcracks and pore defects of the ceramic coating, and obtain a uniform, dense, hole-free and crack-free high-wear-resistant ceramic coating;

[0098] S9. After the processing is completed, the heating unit, the powder spraying unit, the laser cladding unit and the hot rolling unit are turned off.

[0099] Compared with the existing laser cladding technology and hot rolling in-situ film forming technology, the above process method can realize the high-quality in-situ film forming of a strong wear-resistant ceramic layer on the surface of the metal sheet. First, the high-temperature steel plate is preheated by the heating unit. The temperature gradient of the ceramic composite powder during laser cladding is reduced by the preheating effect of the high-temperature steel plate, the thermal stress is reduced, and the microcracks between the substrate and the coating and inside the coating are suppressed. At the same time, the laser cladding unit promotes the melting recrystallization of the ceramic composite powder and the high-temperature metallurgical reaction with the metal elements on the surface of the steel plate through the high-temperature melting effect of the laser, and forms a ceramic layer in situ. Finally, the hot rolling unit uses the high-stress forming characteristics of the roller to suppress the microcracks and hole defects of the ceramic coating, and obtains a uniform, dense, hole-free and crack-free high-wear-resistant ceramic coating, which ultimately improves the mechanical properties and tribological properties of the advanced metal sheet. That is, the present invention improves the mechanical properties and tribological properties of the advanced metal sheet through the mutual coordination and interaction of the heating unit, the powder spraying unit, the laser cladding unit, and the hot rolling unit.

Claims

1. A laser-hot rolling composite in-situ film forming system for a strong wear-resistant ceramic coating on a metal plate, comprising a heating unit, a powder spraying unit, a laser cladding unit and a hot rolling unit arranged in sequence; The heating unit comprises a heating furnace and a conveying roller, wherein the heating furnace is used to heat the metal sheet to obtain a high-temperature metal sheet; and the conveying roller is used to convey the metal sheet; The powder spraying unit includes a powder bin, a powder spraying device and a scraper. The powder bin can store and provide ceramic composite powders. The powder spraying device sprays the ceramic composite powders onto the high-temperature metal plate. The scraper evenly covers the accumulated ceramic composite powders onto the high-temperature metal plate. The laser cladding unit includes a gas storage device, an air jet device and a laser. The gas storage device can store inert gas. The air jet device jets the inert gas to the laser spot on the metal plate. The laser melts the ceramic composite powder layer covering the high-temperature metal plate to form a molten layer. The hot rolling unit comprises two rollers rotating at the same speed and in different directions. A conveying roller delivers a high-temperature metal sheet covered with a molten layer into the rollers for in-situ film-forming and forming rolling.

2. The laser-hot rolling composite in-situ film forming system for strong wear-resistant ceramic coating of metal sheet according to claim 1, characterized in that: The heating temperature of the heating unit is between 50-1500° C., and heating can be achieved under an inert gas atmosphere.

3. The laser-hot rolling composite in-situ film forming system for strong wear-resistant ceramic coating of metal sheet according to claim 1, characterized in that: The ceramic composite powder sprayed out by the powder spraying unit includes 40-60 parts of SiO2, 30-50 parts of B2O3, and 5-15 parts of Al2O3.

4. The laser-hot rolling composite in-situ film forming system for strong wear-resistant ceramic coating of metal sheet as claimed in claim 3, characterized in that: The particle size of the SiO2, B2O3 and Al2O3 powders is 1-10 μm.

5. The laser-hot rolling composite in-situ film forming system for strong wear-resistant ceramic coating of metal sheet as claimed in claim 3, characterized in that: The powder spraying rate of the powder spraying unit is 5-10g / min.

6. The laser-hot rolling composite in-situ film forming system for strong wear-resistant ceramic coating on metal sheet according to claim 1, characterized in that: The laser spot diameter of the laser cladding unit is 2-5 mm, the power is 1-2 kW, the scanning speed is 40-80 mm / s, and the overlap rate of the laser scanning path is 50%-70%.

7. The laser-hot rolling composite in-situ film forming system for strong wear-resistant ceramic coating of metal plate according to claim 1, characterized in that: The rolling rate of the hot rolling unit is 30-60 mm / min, the reduction is 5%-10% of the plate thickness before rolling, and the starting rolling temperature is 900-1200°C.

8. A method for laser-hot rolling composite in-situ film formation of a wear-resistant ceramic coating on a metal sheet surface using the laser-hot rolling composite in-situ film formation system for a strong wear-resistant ceramic coating on a metal sheet as described in any one of claims 1 to 7, characterized in that: The steps include: S1. The SiO2, B2O3 and Al2O3 powders are uniformly mixed to obtain a ceramic composite powder; S2. Place the prepared ceramic composite powder into the powder bin of the powder spraying unit; S3. Pre-treat the surface of the metal sheet to be rolled, clean the oil stains and remove the oxide layer; S4. Set the heating parameters of the heating furnace, put the metal sheet processed in S3 into the heating furnace for heating, and ensure that the temperature of the metal sheet meets the rolling temperature during rolling; S5. Setting powder spraying parameters, using a conveyor roller to convey the metal sheet heated in S4 to the powder spraying unit, ensuring that the ceramic composite powder can evenly cover the surface of the high-temperature metal sheet; S6. Setting laser cladding parameters to ensure that the ceramic composite powder is fully melted before rolling; S7. Setting rolling parameters to ensure uniform film formation of the ceramic layer and that the rolling pressure can effectively reduce the formation of microcracks and pores; S8. Start the heating unit, powder spraying unit, laser cladding unit and hot rolling unit to heat the metal plate to the rolling temperature, and then use the powder spraying unit and laser melting to accelerate the high-temperature metallurgical reaction of the ceramic composite powder and metal elements on the surface of the steel plate to form a ceramic layer in situ. Finally, use the high stress forming characteristics of the rolling roller to suppress the micro cracks and pore defects of the ceramic coating, and obtain a uniform, dense, hole-free and crack-free high wear-resistant ceramic coating, thereby finally improving the wear resistance of advanced metal plates.

9. The laser-hot rolling composite in-situ film forming method for a strong wear-resistant ceramic coating on a metal sheet as claimed in claim 8, characterized in that: The specific process of S1 is as follows: weigh 40-60 parts of SiO2, 30-50 parts of B2O3, and 5-15 parts of Al2O3 powder raw materials, put them into the mixing chamber of the three-dimensional vibration powder mixer, set the mixing rate to 50-100rpm, and the mixing time to 30-60min. After stirring, obtain ceramic composite powder, which is put into the powder bin of the S2 powder spraying unit.

10. The laser-hot rolling composite in-situ film forming method for a strong wear-resistant ceramic coating on a metal sheet as claimed in claim 8, characterized in that: The specific process of S5 is as follows: the ceramic composite powder is sprayed onto the surface of the high-temperature metal plate at a powder spraying rate of 5-10 g / min, and then the composite powder is evenly spread on the surface of the plate using a scraper at a vertical distance of 1-1.5 mm from the plate; The wear resistance of the metal sheet obtained in S8 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 surface of the metal sheet.

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