A new method for preparing laser-synchronous prefabricated high-speed steel roller nanometer oxide ceramic film

Abstract

The application discloses a preparation method of a novel laser synchronous prefabricated high-speed steel roller nanometer oxide ceramic film, which comprises the following steps: firstly, cleaning the surface of the high-speed steel; and then, carrying out phosphating treatment on the surface of the roller; the phosphating treatment is carried out at normal temperature by using an iron-based phosphating solution to generate a dark phosphating film with a thickness of 0.15-0.7 microns; the phosphating film has the characteristics of being loose and porous; nanometer alumina ceramic particles are filled in the internal pores of the phosphating film by ultrasonic spraying; the phosphating film can also be used as a light absorber; and high-power laser is used to irradiate the metal surface to obtain a dense nanometer oxide ceramic film. The nanometer oxide ceramic film is integrated into the surface of the steel, so that the high-temperature oxidation resistance, wear resistance and thermal fatigue resistance of the material can be greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of nano-oxide ceramic film preparation and proposes a novel method for preparing nano-oxide ceramic films for high-speed steel rolls by laser synchronous prefabrication. Background Technology

[0002] Nano-oxide ceramic films possess characteristics such as dense structure, high hardness, wear resistance, and corrosion resistance. Applying a layer of ceramic oxide film to the surface of high-speed steel rolls can replace the oxide film used in the hot rolling process, providing corrosion protection and wear resistance. This allows for better adaptation to the high-temperature, corrosive, and frictional conditions encountered in hot-rolled high-speed steel operations.

[0003] Laser-prepared nano-oxide ceramic films offer several advantages: fine ceramic powder with a large specific surface area, resulting in a dense and uniform coating; the ceramic film itself possesses corrosion resistance, high-temperature resistance, and oxidation resistance; the oxide ceramic has a high melting point, maintaining its nanostructure properties even under rapid heating and cooling conditions during hot rolling under laser irradiation; and laser sintering forms a metallurgical bond with the substrate, simultaneously increasing the hardness and wear resistance of the high-speed steel roll surface. In actual production, there are generally two methods for laser-prepared ceramic coatings: one is the direct forming method, where micron-sized ceramic powders generally have poor formability during laser sintering, and the resulting ceramic coating is porous with poor surface roughness, making it difficult to meet production requirements in engineering applications; the second method is the in-situ generation of carbide ceramics via laser sintering. This method requires very high laser sintering energy input, ensuring that carbon and metal dissolve without burning off the carbides. Furthermore, carbide ceramics tend to deposit or float in the molten pool, often requiring the addition of a binder, significantly altering the surface composition of the substrate, and resulting in uneven carbide formation in the cladding layer, making it unsuitable for preparing thin-layer ceramic films. Addressing the challenges of laser sintering ceramic materials, their inability to stably adhere and retain on steel, and the resulting uneven film formation, this invention utilizes the porous structure of a phosphate film. An ultrasonic nano-spraying device is used to high-speed inject nano-sized alumina particles into the phosphate film, filling it with the porous structure before laser sintering. This solves the problem of ceramic particles failing to adhere to the surface of high-speed steel rolls. Simultaneously, the nanoparticles possess a large specific surface area, excellent performance, and good sintering properties. The phosphate film also acts as a light absorber, forming a uniform, dense, and smooth nano-ceramic coating on the surface. Notably, in the phosphated film, oxygen is used as the gas supply for the ultrasonically sprayed ceramic particles. Under laser sintering, Fe elements are oxidized to generate Fe oxide ceramic particles. Based on the original nano-ceramic material, the Fe oxide ceramic provided by the film acts as a structural support, forming a synergistic, dense oxide ceramic film with the nano-ceramic particles. This film uses Fe oxide as the supporting ceramic and the nano-ceramic film as the substrate.

[0004] In view of this, in order to overcome the shortcomings of direct laser sintering of ceramic coatings and laser-induced in-situ generation of carbide ceramics, this invention proposes a method for simultaneous laser sintering of nano-ceramic films, which can quickly prepare a dense, high-hardness mesh-supported, nano-phase-filled ceramic film on the surface of high-speed steel, with advantages such as high speed, low cost, and high surface finish. Summary of the Invention

[0005] To address the problems of poor forming quality, unstable ceramic particle formation, and uneven film formation associated with laser-direct sintering and laser-induced in-situ generation of carbide ceramics, one objective of this invention is to provide a novel method for preparing nano-oxide ceramic films of high-speed steel rolls using laser synchronous prefabrication. This method features the characteristic of using high-power laser irradiation to create ultra-high temperatures of 1500℃-1850℃ on the surface of the high-speed steel roll.

[0006] Another objective of this invention is to provide a method for prefabricating a laser-absorbing film on the surface of a high-speed steel roll. The method for prefabricating the laser-absorbing film is characterized by using an iron-based phosphating solution for phosphating treatment to prepare an ultra-lightweight porous phosphating film with a film weight of 0.2 to 1 g / m2.

[0007] Another objective of this invention is a method for injecting nano-alumina particles into the pores of a phosphating film at the front end of a laser spot, wherein the phosphating film filling layer has the characteristics of strong adhesion and density.

[0008] To achieve at least one of the above objectives of this invention, the present invention adopts the following technical solution:

[0009] First, pretreatment involves grinding or polishing the surface of the high-speed steel roll to reduce its surface roughness to less than 1.6 μm. Lower roughness results in a smoother oxide film, leading to lower shear friction when used in wear-resistant materials. Therefore, this invention requires a surface roughness below Ra 1.6 μm. After grinding or polishing, the surface is then subjected to alkaline washing to remove oil, followed by rinsing with clean water. The metal surface must be dried within 5 minutes of rinsing with clean water.

[0010] Second, phosphating treatment is performed on the surface of the high-speed steel rolls. This phosphating treatment refers to applying an iron-based phosphating solution to the surface of the high-speed steel rolls at room temperature. The main components of the iron-based phosphating solution are phosphoric acid (H3PO4), sodium dihydrogen phosphate (NaH2PO4), and Fe ions. 2+ Fe 3+ Metal surface dissolution is provided, the oxidant is NaNO3, and the phosphate ions in the phosphating solution are... The concentration should be 10–30 g / L, and the pH value should be 2.0–3.0. The phosphating solution is applied to the steel surface using either a brush or a spraying method. The brushing method involves using a brush or non-woven fabric to absorb the phosphating solution and then applying it to the steel surface. The spraying method uses a spray gun to atomize the phosphating solution and disperse it onto the steel surface. Within 3–10 minutes after coating, a dark-colored, ultra-lightweight phosphating film is formed. This phosphating film is characterized by its porous structure, thin thickness, and low corrosion resistance, with a thickness of 0.15–0.7 μm and a film weight of 0.2–0.9 g / m³. 2 The copper sulfate drop test shows that the corrosion resistance is less than 30-180 seconds. The dark color refers to blue, blue-violet, rainbow, or gray. The specific color is related to the reaction time, the thickness of the phosphating film, and the composition of the phosphating solution.

[0011] Third, a high-temperature laser-prefabricated nano-oxide ceramic film is formed. After the dark phosphating film is generated, an ultrasonic jetting device is used to inject nano-alumina ceramic into the porous structure of the phosphating film, extending it to the leading edge of the laser spot relative to the steel surface, adjacent to the laser spot. The jetting gas supply is oxygen, which oxidizes the iron on the surface of the high-speed steel roll into iron oxide ceramic. The jetting coverage area should be greater than or equal to the laser spot, and the jetting direction should always remain perpendicular to the surface of the high-speed steel roll. The high-energy laser beam irradiates the steel surface. The high-speed steel roll rotates at a high speed ω, which is between 70 rpm and 400 rpm. Simultaneously, the laser head and the jetting pipe move linearly along the axial direction of the cylindrical high-speed steel roll at a speed v, which is between 50 and 450 mm / min. The laser beam spot area is 1 to 12 mm². 2 The overlap rate is 20-70%, and the laser power is 2000W-10000W. Under the irradiation of the high-energy laser beam, the laser spot on the surface of the high-speed steel roll generates an instantaneous high temperature of 1500-1850℃, and a nano-oxide ceramic film that is metallurgically bonded to the surface of the high-speed steel roll is instantaneously sintered at the laser spot.

[0012] The following section provides a detailed description of the process, process parameters, and implementation methods of this invention.

[0013] The purpose of this invention in preparing nano-oxide ceramic films is to improve the friction and wear resistance and high-temperature oxidation resistance of high-speed steel rolls. To improve friction and wear resistance, it is necessary to reduce surface roughness to decrease the coefficient of friction and reduce shear friction. Therefore, the pretreatment process of this invention requires grinding the surface of the high-speed steel roll to a roughness less than Ra 1.6 μm. Simultaneously, to ensure the smooth progress of the subsequent phosphating process, the surface of the high-speed steel roll needs to be degreased and cleaned after grinding, generally by alkaline washing followed by rinsing with clean water. After rinsing with clean water, it must be dried within 5 minutes; otherwise, rust spots may form on the surface, affecting the uniformity of the subsequent phosphating film thickness. This step is consistent with the pretreatment for ultrasonic nano-ceramic particle spraying, which is beneficial for nano-ceramic particle spraying.

[0014] It is important to note that the purpose of phosphating in this invention differs significantly from that of traditional phosphating. Traditional phosphating aims to improve the corrosion and wear resistance of metals, thus requiring a high-density, thick, and corrosion-resistant phosphating film. In contrast, the phosphating film in this invention serves to absorb light and has high porosity. Light absorption refers to the formation of a dark-colored phosphating film, increasing the laser's absorption rate and causing a rapid increase in the surface temperature of the high-speed steel roll. High porosity means that the nano-alumina sprayed in the subsequent laser pre-forming process can penetrate the pores of the phosphating film and contact the surface of the high-speed steel roll, facilitating the formation of a metallurgically bonded nano-oxide ceramic film with the roll surface. Given the two requirements of light absorption and high porosity in this invention, in addition to requiring a dark color, the phosphating film must also be porous, thin, and loose – the exact opposite of the requirements for phosphating films in traditional phosphating processes.

[0015] Because the surface of the workpiece is bright silver after grinding, it has a very high reflectivity to lasers. This leads to low laser efficiency and, for workpieces with curved surfaces, uneven oxide films formed by laser irradiation. The different reflectivity of the same laser spot on the curved surface results in different absorbance at different locations within the same spot. Different absorbance leads to different temperatures, which in turn leads to uneven oxide films. Therefore, this invention proposes forming a dark phosphating film on the workpiece surface, which has two effects: first, the dark phosphating film can significantly improve the absorbance; second, phosphating can serve as a pretreatment step for ultrasonic spraying of nano-ceramic particles, and the porous structure allows the nano-alumina particles to penetrate the film evenly and fully, ensuring uniformity and consistency of quality.

[0016] Depending on the composition of the phosphating solution, phosphating treatments include zinc-based, manganese-based, zinc-calcium-based, and iron-based phosphating. Among them, iron-based phosphating is characterized by the presence of iron (Fe) in the phosphating solution. 2+ Fe 3+Iron ions can be provided by dissolution on the roll surface. Compared with zinc-based, manganese-based, and zinc-calcium-based phosphating, iron-based phosphating has the characteristics of thin phosphating film (less than 1 μm), high porosity, and low density (film weight 0.2–1 g / m²). The phosphating film is mostly bluish-purple in color, but depending on the reaction time, film thickness, and composition of the phosphating solution, it can exhibit iridescent or gray colors. Therefore, dark-colored iron-based phosphating films can be used as laser light absorbers, and their thinness and high porosity allow oxygen to permeate through the phosphating film and contact the iron elements in the steel matrix. Therefore, this invention selects an iron-based phosphating solution to phosphating the surface of high-speed steel roll workpieces.

[0017] During the phosphating process, the surface of the roll substrate reacts with phosphoric acid or hypophosphite in the phosphating solution. Specifically, atoms on the roll surface react with anions in the solution, which act as a medium. Soluble phosphates on the surface continuously convert to insoluble phosphates, ultimately depositing a phosphate conversion film on the roll surface. The main components of iron-based phosphating films are FePO4, Fe3(PO4)2, and Fe(OH)3.

[0018] Phosphate in the phosphating solution of this invention The concentration range differs from that of ordinary phosphating solutions; in this invention, the phosphate group... The concentration is 10–30 g / L, while the concentration of phosphate in ordinary phosphating solutions is generally greater than 30 g / L. In this invention, if phosphate... When the concentration is less than 10 g / L, the membrane is too thin and the color is too light, which is not conducive to improving the absorbance. When the concentration is greater than 30 g / L, the film thickness is too large, the density is increased, which is not conducive to the subsequent penetration of nano-alumina particles. For ordinary phosphating solutions, the goal is to obtain a phosphating film with low porosity, high corrosion resistance, and large thickness. For this invention, the goal is to obtain a phosphating film that is blue-purple, iridescent, or gray, loose and porous, and thin. Therefore, the selection range of phosphating process parameters is different for the two.

[0019] The phosphating film of the present invention is characterized by its blue-purple, iridescent, or gray color, loose and porous structure, thin thickness, and low corrosion resistance, in order to improve laser absorption rate and porosity.

[0020] The pH value of the phosphating solution in this invention differs from that of traditional phosphating solutions. The pH value of the phosphating solution in this invention is 2.0–3.0, while the pH value of traditional phosphating solutions is generally 3.0–4.5. A lower pH value results in a higher hydrogen evolution rate and a looser, more porous film. However, a pH value below 2.0 leads to excessively rapid localized corrosion, resulting in an uneven phosphating film. A pH value above 3.0 increases film density and thickness, which is detrimental to oxygen permeation in subsequent oxygen spraying processes. Traditional phosphating treatments, in order to generate a dense, thick, and corrosion-resistant phosphating film, therefore use a higher pH value in their phosphating solution.

[0021] After preparing the iron-based phosphating solution, it is applied to the surface of the high-speed steel roll using either a brushing or spraying method. The brushing method involves using a brush or non-woven fabric to absorb the phosphating solution and then applying it to the roll surface. The spraying method uses a spray gun to atomize the phosphating solution and disperse it onto the roll surface. After coating, a dark-colored phosphating film is formed. The dark color refers to blue-purple, iridescent, or gray, with the specific color influenced by film thickness, reaction time, and phosphating solution composition. The phosphating film refers to an ultra-lightweight phosphating film with a weight of 0.2–0.9 g / m², a thickness of 0.15–0.7 μm, and a copper sulfate drop test corrosion resistance of less than 30–180 seconds.

[0022] The phosphating time of this invention is 3 to 10 minutes. If the reaction time is less than 3 minutes, rust spots will form and the phosphating film will be incomplete. If the reaction time exceeds 10 minutes, excessive precipitation will occur, increasing the film thickness and decreasing the porosity. In contrast, the conventional phosphating film formation time is 10 to 25 minutes to obtain a phosphating film with sufficient thickness, good density, and strong corrosion resistance.

[0023] Furthermore, no film-forming aids are added to the phosphating solution of the present invention, whereas conventional phosphating solutions require the addition of film-forming aids to achieve a denser film with reduced porosity. The phosphating film of the present invention is required to be porous and thin, so no film-forming aids are needed.

[0024] The concentrated energy of the laser beam can instantly provide enough heat to raise the workpiece surface to the required temperature. After forming a dark, porous phosphating film, ultrasonic nano-ceramic particle jetting and laser irradiation are used to prepare a nano-oxide ceramic film. To rapidly heat the workpiece surface to 1500–1850°C, this invention uses a high-power laser with a small spot size to achieve high energy density. The high-power laser refers to a laser with a power of 2000W–12000W. If the laser power is less than 2000W, the energy is insufficient, and the spot size is too small, which will reduce production efficiency. If the laser power is greater than 12000W, the energy is too high, which may cause overheating. The high-energy laser beam irradiates the surface of the high-speed steel roll, causing the roll to rotate at a high speed ω, which is between 70 rpm and 400 rpm. Simultaneously, the laser head and jet nozzle move linearly along the workpiece axis at a speed v, which is 50–450 mm / min. Higher laser power allows for a correspondingly higher rotation speed. If the rotation speed is below 70 rpm, production efficiency is low; if it exceeds 400 rpm, excessive speed can lead to safety hazards. Therefore, a rotation speed of 70–400 rpm is preferable. If the linear feed speed v of the laser head along the roll axis is below 50 mm / min, production efficiency will be low, and the workpiece surface may overheat due to excessive power density. If the feed speed is above 400 mm / min, the power density on the workpiece surface will be too low to embed the generated nano-ceramic film into the roll surface, preventing metallurgical bonding. Nano-alumina ceramic particles are ultrasonically jetted into the porous structure of the phosphating film. The jetting position is at the front end of the laser spot relative to the roll surface, adjacent to the laser spot. The jetting coverage should be greater than or equal to the laser spot, the jetting thickness is 0.8 μm, and the jetting direction should always remain perpendicular to the roll surface, with constant velocity jetting. The laser spot shape can be circular, square, or rectangular. A small spot refers to a spot area of ​​0.05–16 mm². 2 If the laser spot area is less than 0.05mm 2 This will severely reduce production efficiency if the spot area is greater than 16mm. 2 If the energy density is insufficient, the surface temperature of the rolls will be difficult to reach 1500–1850℃, therefore the spot area is limited to 0.05–16 mm. 2 Ideally, the laser spot overlap rate should be 30% to 80%. If the overlap rate is less than 30%, the laser energy will be insufficient due to the virtual light effect at the edge of the laser spot, resulting in the inability to form a dense nano-oxide ceramic film. If the overlap rate is greater than 80%, the roller surface may melt and overheat.

[0025] The nano-oxide ceramic film prepared by the above method is sintered on the roll substrate, thus exhibiting a metallurgical bond with the steel substrate, resulting in a tight bond, high wear resistance, and resistance to detachment. Furthermore, because the nano-ceramic particles are not melted (their melting point is 2050-2100℃), they retain nanocrystalline characteristics, resulting in a large specific surface area and high surface finish after forming. The roll material surface undergoes slight melting, and the nanoparticles are uniformly and densely embedded in the roll surface, thus achieving a surface roughness identical to that of the original ground workpiece.

[0026] The laser high-temperature oxidation method for generating nano-oxide ceramic films of the present invention has the following significant technical advantages compared with existing direct sintering ceramics and in-situ generation of carbide ceramics:

[0027] 1. The method of simultaneously spraying and sintering pre-prepared nano-ceramic oxide film after phosphating according to the present invention has the advantages of being fast, energy-saving, low-cost, and pollution-free. Compared with traditional direct sintering and in-situ generation of carbide ceramics, it has high feasibility and is easy to industrialize.

[0028] 2. The method of simultaneously spraying and sintering pre-prepared nano-ceramic oxide film after phosphating according to the present invention has the advantages of being fast, energy-saving, low-cost, and pollution-free. Compared with traditional direct sintering and in-situ generation of carbide ceramics, it has high feasibility and is easy to industrialize.

[0029] 3. The present invention produces a nano-oxide ceramic film with dense structure, high hardness, and tight bonding with the substrate, making it difficult to peel off;

[0030] 4. The present invention produces a nano-oxide ceramic film with dense structure, high hardness, and tight bonding with the substrate, making it difficult to peel off;

[0031] 5. The present invention uses a loose and porous phosphating film as a light absorber and a method for infiltrating nano-ceramic particles, which significantly reduces the laser reflectivity and improves the uniformity of the light intensity distribution on the laser spot. While improving the light absorption rate, it can also perform a nano-spraying pretreatment step, so that the nano-ceramic particles can be uniformly and fully infiltrated into the phosphating film, thereby improving the uniformity of the prepared nano-oxide ceramic film. Detailed Implementation

[0032] To illustrate the technical means and inventive features of this invention, specific embodiments are described in further detail below. However, this invention is not limited to these embodiments. The preferred embodiments described below are merely examples, and those skilled in the art can conceive of other obvious variations. The basic principles of this invention defined in the following description can be applied to other implementation schemes, modifications, improvements, equivalent schemes, and other technical solutions that do not depart from the spirit and scope of this invention.

[0033] The present invention discloses a novel laser-prefabricated nano-oxide ceramic film method that improves the high-temperature wear resistance and oxidation resistance of high-speed steel rolls by forming a nano-oxide ceramic film on the surface of the rolls, thereby extending their service life. The preparation process consists of three steps: roll face treatment, phosphating treatment, ultrasonic spraying of nano-alumina ceramic particles, and synchronous high-temperature laser radiation. Specific applications are described in the following embodiments.

[0034] Example 1

[0035] A nano-Fe3O4 oxide film was prepared on the surface of a high-speed steel roll with a diameter of 800 mm. The specific process is as follows: First, pretreatment: the workpiece after grinding was degreased with alkali and rinsed with water. After rinsing, it was dried with hot air. The surface of the cleaned workpiece was bright silver. Second, phosphating treatment: the phosphate concentration in the phosphating solution was 25 g / L, and the pH value was 2.5. The phosphating solution was coated onto the steel surface by brushing. Four minutes after coating, a blue phosphating film was formed with a thickness of 0.4 μm and a film weight of 0.5 g / m2. The corrosion resistance was tested by the copper sulfate drop method for 150 seconds. Third, ultrasonic spraying of nano-alumina ceramic particles was performed. The laser power was 5 kW, the spot diameter was 2.5 mm, the overlap rate was 50%, the workpiece rotation speed was 120 rpm, the axial feed speed of the laser head was 80 mm / min, and the ultrasonic spraying gas supply was oxygen.

[0036] Example 2:

[0037] A Fe3O4 oxide film was prepared on the surface of a 700mm diameter high-speed steel roll. The specific process was as follows: First, pretreatment: the workpiece after grinding was degreased with alkali and rinsed with water. After rinsing, it was dried with hot air, and the surface of the cleaned workpiece was bright silver. Second, phosphating treatment: the phosphate concentration in the phosphating solution was 30g / L, and the pH value was 2.2. The phosphating solution was coated onto the steel surface by brushing. Six minutes after coating, a gray phosphating film was formed with a thickness of 0.5μm and a film weight of 0.6g / m2. The corrosion resistance was tested by the copper sulfate drop method for 170 seconds. Third, ultrasonic spraying of nano-alumina ceramic particles was performed under synchronous laser irradiation. The laser power was 6kW, the spot diameter was 2.5mm, the overlap rate was 50%, the workpiece rotation speed was 130rpm, the axial feed speed of the laser head was 90mm / min, and the ultrasonic spraying gas supply was oxygen.

[0038] Therefore, it can be seen that the oxide film high-speed steel roll prepared by the method of the present invention has a very significant effect on reducing workpiece oxidation and wear, and can significantly improve the service life of high-speed steel.

[0039] Example 3:

[0040] The oxyanion-containing activating solution was prepared to contain phosphate ions (PO4). 3- Iron-based phosphating solution.

[0041] Preferably, the main components of the iron-based phosphating solution are phosphoric acid (H3PO4) and sodium dihydrogen phosphate (NaH2PO4), with NaNO3 as the oxidant and Fe as the oxidant. 2+ Fe 3+ It is generated by the reaction of iron atoms on the surface of the high-speed steel roll with phosphating solution.

[0042] It is worth mentioning that, in this embodiment, the iron-based phosphating solution is phosphate (PO4). 3- Iron-based phosphating solution with a concentration of 10–30 g / L and a pH value of 2.0–3.0.

[0043] Depending on the composition of the phosphating solution, phosphating treatments include zinc-based, manganese-based, zinc-calcium-based, and iron-based phosphating. Among them, iron-based phosphating is characterized by the presence of iron (Fe) in the phosphating solution. 2+ Fe 3+ Iron ions can be provided by dissolving ions from the steel surface. Compared with zinc-based, manganese-based, and zinc-calcium-based phosphating, iron-based phosphating has the characteristics of thin phosphating film (less than 1 μm), high porosity, and low density (film weight 0.2–1 g / m²). The phosphating film is mostly bluish-purple in color, but depending on the reaction time, film thickness, and composition of the phosphating solution, it can exhibit iridescent or gray colors. Therefore, dark-colored iron-based phosphating films can be used as laser light absorbers, and their thinness and high porosity allow nano-alumina to fill the phosphating film and come into contact with the steel substrate. Therefore, this invention uses an iron-based phosphating solution to activate the surface of high-speed steel rolls.

[0044] During the phosphating process, the surface of the high-speed steel roll substrate reacts with phosphoric acid or hypophosphate in the phosphating solution. Specifically, atoms on the outer layer of the high-speed steel roll react with anions in the solution, which act as a medium. Soluble phosphates on the surface continuously convert to insoluble phosphates, ultimately depositing a phosphate conversion film on the surface of the high-speed steel roll. The main components of the iron-based phosphating film are FePO4, Fe3(PO4)2, and Fe(OH)3.

[0045] In this embodiment, the phosphate solution contains phosphate (PO4). 3- The concentration range of phosphate (PO4) differs from that of ordinary phosphating solutions. In this invention, the phosphate group (PO4) has a different concentration range. 3- The concentration of phosphate ions is 10–30 g / L, while the concentration of phosphate ions in ordinary phosphating solutions is generally greater than 30 g / L. In this invention, if the concentration of phosphate ions (PO4) is 10–30 g / L, then the concentration of phosphate ions is 10–30 g / L. 3- When the phosphate concentration is less than 10 g / L, the membrane is too thin and the color is too light, which is not conducive to improving the absorbance. 3-When the concentration is greater than 30 g / L, the film thickness is too large, the density is increased, which is not conducive to the penetration of nano-alumina ceramics. For ordinary phosphating solutions, the goal is to obtain a phosphating film with low porosity, high corrosion resistance, and large thickness. For this invention, the goal is to obtain a phosphating film that is blue-purple, iridescent, or gray, loose and porous, and thin. Therefore, the selection range of phosphating process parameters is different for the two.

[0046] The phosphating film in this embodiment is characterized by its blue-purple, iridescent, or gray color, thin thickness, high porosity, and low corrosion resistance, in order to improve the laser absorption rate.

[0047] The phosphating film in this implementation case has a different main function. It mainly utilizes its loose and porous structure to fill nano-alumina ceramic particles, increasing their adhesion. It can also be equivalent to the chemical pretreatment step of ultrasonic nano-spraying to obtain a dense and uniform nano-ceramic film.

[0048] In this embodiment, the pH value of the phosphating solution also differs from that of traditional phosphating solutions. The pH value of the phosphating solution in this invention is 2.0–3.0, while the pH value of traditional phosphating solutions is generally 3.0–4.5. A low pH value results in a high hydrogen evolution rate and a loose, porous film. However, a pH value below 2.0 leads to excessively rapid local corrosion, resulting in an uneven phosphating film. A pH value above 3.0 increases film density and thickness, which is not conducive to the subsequent penetration of nano-alumina ceramic particles. In contrast, traditional phosphating treatments use a higher pH value in order to generate a dense, thick, and corrosion-resistant phosphating film.

[0049] Those skilled in the art should understand that the above-described embodiments of the present invention are merely examples and do not limit the invention. The objectives of the present invention have been fully and effectively achieved. The functions and structural principles of the present invention have been shown and explained in the embodiments. Without departing from the stated principles, the implementation of the present invention may have any variations or modifications.

Claims

1. A novel method for preparing a laser-synchronously prefabricated nano-oxide ceramic film for high-speed steel rolls, characterized in that, High-energy laser irradiation is used to create localized high temperatures on the surface of the roll, which rapidly sinters the phosphating film on the metal surface. This fuses the nano-ceramic particles inside the phosphating film with the metal surface, forming a dense nano-oxide ceramic film.

2. The method for preparing a novel laser-synchronously prefabricated high-speed steel roll nano-oxide ceramic film according to claim 1, characterized in that, The nano-ceramic particles filling the phosphate film are applied near the phosphate film via ultrasonic spraying.

3. The method for preparing a novel laser-synchronously prefabricated high-speed steel roll nano-oxide ceramic film according to claim 1, characterized in that, While the surface of the high-speed steel roll is irradiated by a laser, nano-ceramic powder is sprayed onto the front end of the laser spot on the surface of the high-speed steel roll to fill the phosphate film, and the nano-oxide ceramic filling area can be close to the laser spot.

4. The method for preparing a novel laser-synchronously prefabricated high-speed steel roll nano-oxide ceramic film according to claim 1, characterized in that, The nano-ceramic particles are nano-spherical alumina with a crystal form of γ-Al2O3 and a particle size of 20 nm; the specific surface area is ≥230 m2 / g.

5. The method for preparing a novel laser-synchronously prefabricated high-speed steel roll nano-oxide ceramic film according to claim 1, characterized in that, The high temperature is 1500–1850℃.

6. The method for preparing a novel laser-synchronously prefabricated high-speed steel roll nano-oxide ceramic film according to claim 1, characterized in that, The thickness of the nano-oxide ceramic film is 0.2–0.8 μm, and it is metallurgically bonded to the substrate.

7. The method for preparing a novel laser-synchronously prefabricated high-speed steel roll nano-oxide ceramic film according to claim 1, characterized in that, Before laser irradiation of the surface of high-speed steel rolls, the surface of high-speed steel rolls is first subjected to phosphate treatment to form a phosphate film on the surface of high-speed steel rolls.

8. The method for preparing a novel laser-synchronously prefabricated nano-oxide ceramic film for high-speed steel rolls according to claim 7, characterized in that, The phosphating treatment refers to phosphating with an iron-based phosphating solution, wherein the phosphate group in the phosphating solution... The concentration is 10–30 g / L, the pH value is 2.0–3.0, and the phosphating treatment time is 3–10 minutes.

9. The method for preparing a novel laser-synchronously prefabricated high-speed steel roll nano-oxide ceramic film according to claim 3, characterized in that, The phosphating film is a dark-colored, ultra-lightweight phosphating film with a thickness of 0.15–0.7 μm and a film weight of 0.2–0.9 g / m². The copper sulfate drop method corrosion resistance test time is 30–180 seconds.

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