Preparation method of laser cladding reinforced wear-resistant coating for continuous casting crystallizer copper plate

Abstract

The invention belongs to the technical field of laser cladding and metal surface repair, and relates to a preparation method of a laser cladding reinforced wear-resistant coating for a continuous casting crystallizer copper plate, firstly, an intermediate coating for laser cladding of the surface of the copper plate is prepared by using a binder and metal powder, and the laser reflectivity of the prepared intermediate coating is greatly reduced compared with that of the copper plate; then, a laser pre-cladding process is carried out on the surface of the copper plate, so that firm metallurgical bonding is generated between the intermediate coating and the copper plate, and conditions are created for the laser cladding process for strengthening the wear-resistant layer; and finally, the continuous casting crystallizer copper plate coating of which the wear-resisting property at the high temperature of 300 DEG C is obviously superior to that of a traditional electroplating coating is obtained by designing material components of a strengthened wear-resisting layer and a laser cladding process, and the industrial problem that laser cladding is difficult to directly carry out on the surface of a traditional copper plate is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of laser cladding and metal surface repair, and relates to a preparation method of a laser cladding reinforced wear-resistant coating for a continuous casting mold copper plate. BACKGROUND

[0002] In the continuous casting operation process of a steel plant, the mold is a core component, and the quality of the mold copper plate is the most important. It has a crucial influence on the quality of the continuous casting billet, the cost of continuous casting and production efficiency. In actual production, the mold copper plate will face many problems. Due to long-term work in a complex and harsh environment, the surface of the mold copper plate is prone to local wear, corrosion, thermal cracks and deformation. These problems not only shorten the service life of the mold copper plate itself, but also reduce the quality of the continuous casting billet and increase the production cost. To solve these problems, the industry generally adopts the method of surface modification on the surface of the copper plate. Specifically, a layer of special material is electroplated or sprayed on the surface of the copper plate to obtain a surface modified coating with multiple excellent properties. This coating needs to meet the requirements of good thermal conductivity, not easy to fall off, high wear resistance and strong corrosion resistance, so as to adapt to the actual working condition requirements. Practice shows that the existence of the copper plate surface coating has remarkable effect, effectively prolongs the service life of the mold copper plate, improves the quality of the continuous casting billet, and ultimately realizes the goal of reducing the ton steel casting cost.

[0003] In recent years, with the continuous progress of science and technology, key technologies such as high-power laser and high-precision mechanical control system have realized localization development and gradually matured. This change has greatly reduced the technical cost and application threshold of laser cladding technology. Laser cladding technology has shown strong vitality due to its unique advantages. It has excellent organizational performance control capability and can accurately adjust the organizational structure of the material according to different needs. It adopts an efficient production mode, which can greatly improve the production efficiency. At the same time, it also has the characteristics of green environmental protection, which meets the concept of sustainable development at present. Therefore, this technology has been widely used in many fields such as aerospace, petroleum chemical industry and metallurgical equipment.

[0004] In the field of continuous casting mold copper plate coating preparation technology, compared with mainstream processes such as electroplating and thermal spraying, laser cladding technology has the advantages of stronger adhesion, higher heat resistance and corrosion resistance, and more excellent high-temperature wear resistance. However, the application of laser cladding technology on the mold copper plate is not smooth. Due to the high reflectivity of the mold copper plate to laser, it is difficult to directly perform laser cladding operation on its surface, which seriously limits the large-scale popularization and application of laser cladding technology on the mold copper plate. Therefore, how to solve this problem and realize the effective application of laser cladding technology on the mold copper plate has become a key technology to be conquered at present. SUMMARY

[0005] In view of this, the purpose of the present invention is to provide a method for preparing a laser cladding strengthened wear-resistant coating for a continuous casting crystallizer copper plate. First, an intermediate coating for laser cladding on the surface of a copper plate is prepared using a powder binder and metal powder. The laser reflectivity of the prepared intermediate coating is significantly lower than that of the copper plate. Then, a laser pre-cladding process is performed on its surface to produce a strong metallurgical bond between the intermediate coating and the copper plate, thereby creating conditions for the laser cladding process of the strengthened wear-resistant layer. Finally, by designing the material composition of the strengthened wear-resistant layer and the laser cladding process, a continuous casting crystallizer copper plate coating is obtained whose high-temperature wear resistance at 300°C is significantly better than that of traditional electroplating coatings, so as to solve the technical problems raised in the background technology.

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

[0007] A method for preparing a laser cladding reinforced wear-resistant coating for a continuous casting mold copper plate comprises the following steps:

[0008] Preparation of intermediate coating: weigh metal powder and binder and pre-mix them to obtain a colloidal mixture;

[0009] Intermediate coating homogenization treatment: the pre-mixed colloidal mixture is subjected to acoustic resonance treatment;

[0010] Post-treatment of the intermediate coating: the colloidal mixture after the acoustic resonance treatment is evenly applied on the copper plate of the crystallizer to form an intermediate coating on the surface of the copper plate of the crystallizer, and then dried;

[0011] Laser pre-cladding of the intermediate coating on the copper plate surface: Laser pre-cladding of the intermediate coating on the surface of the crystallizer copper plate;

[0012] Preparation of the reinforced wear-resistant layer powder: weighing one or more of nickel-based powder, cobalt powder and reinforcing ceramic particles, and mixing the powders to obtain the reinforced wear-resistant layer powder;

[0013] Laser cladding of the copper plate surface strengthening wear-resistant layer: using the strengthening wear-resistant layer powder as raw material, laser cladding is performed on the intermediate coating on the surface of the crystallizer copper plate after laser pre-cladding to obtain the laser cladding strengthening wear-resistant coating for the continuous casting crystallizer copper plate.

[0014] Furthermore, the intermediate coating preparation step further includes weighing a surfactant and premixing it with the metal powder and the binder, and the mass fraction ratio is: metal powder 80-95%, binder 4-20%, surfactant 0-3%.

[0015] Further, the metal powder comprises at least one of pure Ni, NiCo alloy, Ni60, Inconel 718, Inconel 625, GH1140, GH4169, GH2132, GH3030, GH3044 and GH3128; the particle size range is 15-150 μm, the morphology is spherical or near-spherical, and the purity is above 99%;

[0016] The binder comprises at least one of polyvinyl alcohol, polyvinyl acetate, polyvinyl acetal, acrylate, polyvinyl chloride, sodium silicate, potassium silicate, copper oxide, aluminum phosphate, magnesium phosphate and a solution of each of the above;

[0017] The surface active substance comprises at least one of titanate, stearate, silicate and silane.

[0018] Further, in the intermediate coating preparation step, a V-type mixer is used for pre-mixing, the mixing speed is 50 rpm-400 rpm, and the mixing time is 0.5-9 h.

[0019] Further, in the intermediate coating homogenization treatment step, a sound resonance device is used for sound resonance treatment, and the sound resonance treatment comprises high-frequency mixing: frequency 90 Hz, acceleration 40-100 g, mixing time 1 min-10 min; and

[0020] Low-frequency mixing: frequency 60 Hz, acceleration 40-100 g, mixing time 5 min-60 min.

[0021] Further, in the intermediate coating post-treatment step, a mold and a scraper device are used to uniformly spread the gel-like mixture after sound resonance treatment on the copper plate of the crystallizer, the spreading height is 0.2 mm-0.5 mm, and then the copper plate is placed in a vacuum drying oven for drying, the temperature is 50-80 ℃, and the time is 3-6 h.

[0022] Further, in the copper plate surface intermediate coating laser pre-melting step, a continuous Nd:YAG laser is used for pre-melting, the laser power is 0.5-1.5 KW, the spot diameter is 2-5 mm, the protective gas flow is 15-25 L / min, the scanning interval is 1-3 mm, the scanning speed is 10-30 mm / s, and no powder feeding is performed.

[0023] After pre-melting is completed, the surface is cleaned and polished.

[0024] Further, in the preparation step of the strengthened wear-resistant layer powder, the mass fraction of the raw material of the strengthened wear-resistant layer composite powder is as follows: nickel-based powder 70-100%, cobalt powder 0-30%, and enhanced phase ceramic particles 0-10%.

[0025] The cobalt powder is spherical pure cobalt powder with purity of 99% or above, and particle size range of 20-150 mu m;

[0026] The reinforcing phase ceramic particles include at least one of TiC, B4C, WC, TiB2, TiB and ZrB, and average particle size of 0.5-5 mu m;

[0027] The powder mixing treatment is performed by using a sound resonance device, and the powder mixing treatment includes high-frequency mixing: frequency of 90 Hz, acceleration of 30-100 g, and mixing time of 1 min-10 min; and

[0028] Low-frequency mixing: frequency of 60 Hz, acceleration of 30-100 g, and mixing time of 5 min-60 min;

[0029] After the powder mixing treatment is completed, the copper plate is placed in a drying box for drying.

[0030] Further, in the laser cladding step of the surface strengthening wear-resistant layer of the copper plate, a continuous Nd:YAG laser is used for cladding, laser power is 3-6 KW, spot diameter is 2-5 mm, protective gas flow is 15-25 L / min, scanning spacing is 1-3 mm, scanning speed is 2-6 mm / s, and powder feeding speed is 1.5-2.5 r / min;

[0031] And after the laser cladding is completed, the surface is machined to be flat, so as to obtain a laser cladding strengthened wear-resistant coating for a continuous casting crystallizer copper plate.

[0032] Further, the material of the crystallizer copper plate is chromium-zirconium copper, silver copper, red copper or brass.

[0033] The present application has the following beneficial effects:

[0034] 1. The present application provides a preparation method of an intermediate coating for laser cladding of a continuous casting crystallizer copper plate, which obtains an intermediate layer that can be directly used for laser cladding on the surface of a copper plate by designing the coating composition and coating preparation process. The existence of the intermediate layer effectively reduces the laser reflectivity of the copper plate, and the composition has a high solid solubility in copper, which can produce a firm metallurgical bond with the copper plate after laser processing. The subsequent laser cladding process can be carried out on the surface of the intermediate layer, thereby providing a solution to the industry problem that the surface of the traditional copper plate is difficult to directly perform laser cladding.

[0035] 2. The present application solves the problems of uneven distribution and uneven composition of the pre-coating in the traditional pre-powder laser cladding method, thereby avoiding the incomplete melting of the powder caused by the agglomeration of the metal powder during the cladding process, thereby producing defects in the local area, and further causing the problem of poor coating cladding quality or even cracking.

[0036] 3. The intermediate coating prepared by the method of the present application can continue the cladding process on the intermediate coating with low laser reflectivity after pre-cladding, thereby avoiding the problem that it is difficult to directly cladding the strengthened wear-resistant coating on the surface of the copper plate with high reflectivity, and finally obtaining the strengthened wear-resistant laser cladding coating with significantly better wear resistance than the traditional electroplated coating.

[0037] 4. The intermediate coating and the strengthened wear-resistant layer prepared by the method of the present application have simple preparation process, uniform coating distribution, high production efficiency, no harmful substances generated in the process, no environmental pollution, high environmental protection, low cost of raw materials such as binders, high economic value, and are suitable for batch preparation of laser cladding wear-resistant coating of large copper plates such as continuous casting crystallizers.

[0038] Other advantages, objects, and features of the present application will be apparent to those skilled in the art from the following specification, and will be learned from the practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the following specification. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to make the objects, technical solutions and advantages of the present application clearer, the preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, in which:

[0040] Figure 1 A physical diagram of the intermediate coating laid on the chromium-zirconium-copper plate without drying in the example;

[0041] Figure 2 A physical diagram of the intermediate coating after drying in the drying box in the example;

[0042] Figure 3 A micro-morphology diagram of the strengthened wear-resistant layer powder in the example;

[0043] Figure 4 A comparison diagram of the wear resistance of the laser cladding strengthened wear-resistant layer and the traditional electroplated layer in the example. DETAILED DESCRIPTION

[0044] The embodiments of the present application will be described below by specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the present specification. The present application can also be implemented or applied by different specific embodiments, and the details in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the diagrams provided in the following examples only illustrate the basic concept of the present application in a schematic manner, and the following examples and features in the examples can be combined with each other without conflict.

[0045] The drawings are only used for illustrative description, and the representation is only a schematic diagram, not a physical diagram, and cannot be understood as a limitation on the present application; in order to better illustrate the embodiments of the present application, some components in the drawings are omitted, enlarged or reduced, and do not represent the size of the actual product; it is understandable for those skilled in the art that some well-known structures and their descriptions in the drawings can be omitted.

[0046] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it is understood that if the terms 'upper', 'lower', 'left', 'right', 'front', 'back' and the like indicate the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for illustrative description, and cannot be understood as a limitation on the present application, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0047] Embodiment 1

[0048] The present embodiment provides a preparation method of laser cladding reinforced wear-resistant coating for continuous casting crystallizer copper plate, which is specifically carried out according to the following steps:

[0049] Step one: intermediate coating preparation

[0050] An appropriate amount of metal powder, liquid binder and surface active substance are weighed and put into a V-type mixer for pre-mixing, the mixing speed is 50rpm-400rpm, and the mixing time is 0.5-9h, the purpose is to uniformly mix and pretreat the metal powder and the binder.

[0051] Step two: homogenization treatment of intermediate coating

[0052] The pre-mixed gelatinous mixture is transferred to a sound resonance device for multi-stage processing;

[0053] (1) high frequency mixing, frequency 90hz, acceleration 40-100g, mixing time 1min-10min, the purpose is to break the agglomeration of metal powder inside the gelatinous substance by using the shear stress generated by high frequency vibration, so that the metal powder and the liquid binder are uniformly mixed.

[0054] (2) medium-low frequency mixing, frequency 60hz, acceleration 40-100g, mixing time 5min-60min, the purpose is to continuously act on the pre-mixed coating by using the energy generated by medium frequency vibration, so that the metal powder is uniformly dispersed in the binder without local powder agglomeration.

[0055] Step three: post-treatment of intermediate coating

[0056] The mixed coating is taken out of the acoustic resonance device, and the coating is evenly applied on the crystallizer copper plate by using a mold and a scraper device. During the application process, the coating should be applied at a slow and uniform speed to avoid the generation of bubbles in the coating. Then, the copper plate with the coating is placed in a vacuum drying oven for drying. The temperature of the drying oven is 50-80℃, and the drying time is 3-6h.

[0057] The presence of the intermediate coating effectively reduces the laser reflectivity of the chromium-zirconium-copper copper plate. Due to the high nickel content in the coating composition, the solid solubility in copper is good, and after the laser pre-cladding process, a firm metallurgical bond can be formed with the chromium-zirconium-copper plate, which can be used for subsequent laser cladding process of the strengthening wear-resistant layer on the intermediate layer.

[0058] Step four: laser pre-cladding of intermediate coating on the surface of the copper plate

[0059] The intermediate coating is laser pre-cladded by using a continuous Nd:YAG laser. The specific process parameters are as follows: laser power 0.5-1.5KW, spot diameter 2-5mm, protective gas flow 15-25L / min, scanning interval 1-3mm, scanning speed 10-30mm / s, and no powder feeding. A faster scanning speed and smaller laser power are used for full-surface cladding of the intermediate layer. Due to the low laser reflectivity of the intermediate layer, the energy input into the coating can form a firm metallurgical bond between the coating and the copper plate, which is used for cladding the outermost strengthening wear-resistant layer.

[0060] After laser pre-cladding of the intermediate coating, the surface of the coating is cleaned and polished using alcohol and sandpaper. After removing the oxidation layer, it can be used for laser cladding process of the strengthening wear-resistant layer.

[0061] Step five: preparation of strengthening wear-resistant layer powder

[0062] Since the intermediate coating composition is mainly composed of nickel elements, a nickel-based powder is used as the matrix powder of the strengthening wear-resistant layer to ensure good fusion between the strengthening wear-resistant layer and the intermediate coating. An appropriate amount of ceramic particles, spherical cobalt powder, and spherical nickel-based powder are weighed and subjected to multi-stage powder mixing treatment by using an acoustic resonance device.

[0063] (1) High-frequency mixing, frequency 90hz, acceleration 30-100g, mixing time 1min-10min, the purpose is to break the agglomeration of fine powders and improve the uniformity of the next step.

[0064] (2) Middle-low frequency mixing, frequency 60hz, acceleration 30-100g, mixing time 5min-60min, the purpose is to make the ceramic particles uniformly coated on the surface of the nickel and cobalt powders.

[0065] The mixed powder is placed in a drying oven to keep dry, and then the laser cladding process of the strengthened wear-resistant layer on the surface of the pre-melted intermediate coating is carried out in the next step.

[0066] Step six: laser cladding of the strengthened wear-resistant layer on the surface of the copper plate

[0067] The laser cladding process of the strengthened wear-resistant layer is carried out by using a continuous Nd:YAG laser, and the specific process parameters are as follows: laser power 3-6 KW, spot diameter 2-5 mm, protective gas flow rate 15-25 L / min, scanning interval 1-3 mm, scanning speed 2-6 mm / s, powder feeding speed 1.5-2.5 r / min, and the powder is the strengthened wear-resistant layer powder prepared in step five. The entire surface of the strengthened layer is cladded by using a slower scanning speed and a larger laser power, so that a certain thickness and uniform microstructure of the laser cladding layer can be obtained while ensuring that the strengthened layer powder is fully melted. After the surface is ground flat by machining, the copper plate can be used in the working condition of the continuous casting mold.

[0068] It should be noted that the order of the steps provided in the embodiment is only a preferred scheme and is not the only limitation. In practice, step five: preparation of the strengthened wear-resistant layer powder and step one: preparation of the intermediate coating can be carried out simultaneously, or step one can be carried out first, or they can be carried out at other times.

[0069] Preferably, in step one, the mass fraction of the metal powder, the binder and the surface active substance is as follows: the metal powder accounts for 80-95%, the binder accounts for 4-20%, and the surface active substance accounts for 0-3%.

[0070] Preferably, in steps one and five, the metal powder includes at least one of various laser cladding nickel-based alloys (such as pure Ni, NiCo alloy, Ni60, Inconel 718, Inconel 625, GH1140, GH4169, GH2132, GH3030, GH3044 and GH3128, etc.) or other alloy powders with high solid solubility in copper.

[0071] Preferably, in step one, the particle size of the metal powder ranges from 15 to 150 μm, and the powder morphology is spherical or near-spherical, with a purity of more than 99%.

[0072] Preferably, in step one, the binder includes at least one of organic binders (such as polyvinyl alcohol, polyvinyl acetate, polyvinyl acetal, acrylic ester and polyvinyl chloride, etc.) and solutions thereof, inorganic binders (such as sodium silicate, potassium silicate, copper oxide, aluminum phosphate and magnesium phosphate, etc.) and solutions thereof.

[0073] Preferably, in step one, the surface active material includes at least one of titanium salt, stearate, silicate and silane, etc., and the active material mainly serves to reduce the viscosity of the mixture and increase the fluidity.

[0074] Preferably, in step three, the copper plate material of the crystallizer includes common crystallizer copper materials such as chromium-zirconium copper, silver copper, red copper and brass.

[0075] Preferably, in step three, the intermediate coating that can be directly used for laser cladding on the surface of the copper plate has a height of 0.2mm-0.5mm, so the height of the mold should be slightly higher than that of the copper plate by 0.2mm-0.5mm. The moving direction of the scraper device (a conventional device in the prior art, which will not be described herein) is horizontal movement, and the device maintains stable operation at a constant speed during the movement process without any shaking or movement failure of the scraper.

[0076] Preferably, in step five, the mass fraction of the composite powder raw material of the reinforced wear-resistant layer is as follows: the proportion of nickel-based powder is 70-100%, the proportion of cobalt powder is 0-30%, and the proportion of the reinforcing phase ceramic particles is 0-10%.

[0077] Preferably, in step five, the cobalt powder is spherical pure cobalt powder with a purity of more than 99% and a particle size range of 20-150μm.

[0078] Preferably, in step five, the reinforcing phase ceramic particles include at least one of carbides (TiC, B4C, WC, etc.) and borides (TiB2, TiB, ZrB, etc.) with an average particle size of 0.5-5μm.

[0079] Example 2

[0080] The embodiment provides a preparation method of a laser cladding reinforced wear-resistant coating for a continuous casting crystallizer copper plate. First, an intermediate coating for laser cladding on the surface of a chromium-zirconium copper plate is prepared by using a liquid binder polyvinyl alcohol and pure metal nickel powder. Since the laser reflectivity of the intermediate coating composition is low and the intermediate coating can be well metallurgically combined with the copper plate, a subsequent laser cladding process of a reinforced wear-resistant coating can be performed on the surface of the intermediate coating. Then, a powder composition and a preparation process of the reinforced wear-resistant layer are designed by using Ni60A powder, pure Co powder and WC ceramic particles. Finally, a laser cladding process of the reinforced wear-resistant layer powder is continuously performed on the intermediate coating with low laser reflectivity, so that the laser cladding reinforced wear-resistant coating with a high-temperature wear resistance significantly better than that of a traditional electroplated coating at 300℃ is obtained. The method specifically includes the following steps:

[0081] Step one: intermediate coating preparation

[0082] An appropriate amount of metal powder and binder is put into a V-shaped mixer for pre-mixing, the mixing speed is 200rpm, and the mixing time is 0.5h, so as to uniformly mix and pretreat the metal powder and the binder.

[0083] Step two: intermediate coating homogenization treatment

[0084] The premixed gelatinous mixture is transferred to a sound resonance device for multi-stage processing.

[0085] (1) High-frequency mixing, frequency 90hz, acceleration 40g, mixing time 5min, the purpose is to break the agglomeration of metal powder inside the gelatinous material by using the shear stress generated by high-frequency vibration, and to mix the metal powder and the binder macroscopically uniformly.

[0086] (2) Medium-low frequency mixing, frequency 60hz, acceleration 80g, mixing time 30min, the purpose is to continuously act on the premixed coating by using the energy generated by medium-frequency vibration, so that the metal powder is uniformly dispersed in the binder without local powder agglomeration.

[0087] Step three: intermediate coating post-treatment

[0088] The uniformly mixed coating is taken out of the sound resonance device, and a mold and a scraper device are used to evenly apply the coating on the chromium-zirconium-copper crystallizer copper plate. During the application process, the speed should be uniform and slow to avoid air bubbles in the coating. The actual object obtained is shown in Figure 1 . Then the copper plate is placed in a vacuum drying oven for drying, with a drying oven temperature of 60°C and a drying time of 4h. After drying, the actual object obtained is shown in Figure 2 .

[0089] Step four: chromium-zirconium-copper copper plate surface laser pre-cladding

[0090] A continuous Nd:YAG laser is used for single-layer laser cladding, and the specific process parameters are as follows: laser power 1.5KW, spot diameter 2mm, protective gas flow 20L / min, scanning interval 2mm, scanning speed 10mm / s, and no powder is sent. After laser cladding of the intermediate coating, the surface of the coating is cleaned and polished using alcohol and sandpaper, obtaining an intermediate coating with low laser reflectivity that can be directly used for chromium-zirconium-copper copper plate surface laser cladding. After removing the oxide layer, it can be used for subsequent laser cladding process of the strengthening wear-resistant layer.

[0091] Step five: strengthening wear-resistant layer powder preparation

[0092] Ni-based powder is used as the matrix powder of the strengthening wear-resistant layer, so as to ensure good metallurgical bonding between the strengthening wear-resistant layer and the intermediate coating. An appropriate amount of reinforcing phase ceramic particles, spherical cobalt powder and spherical Ni-based powder are weighed and subjected to multi-stage powder mixing treatment using a sound resonance device.

[0093] (1) High frequency mixing, frequency 90hz, acceleration 80g, mixing time 6min, the purpose is to break the agglomeration of fine powder, and improve the uniformity of the next step mixing.

[0094] (2) Low frequency mixing, frequency 90hz, acceleration 80g, mixing time 20min, the purpose is to make the ceramic particles uniformly coated on the surface of nickel powder and cobalt powder.

[0095] The mixed powder is placed in a drying oven at 100℃ for 4h, preparing for the laser cladding process of the strengthened wear-resistant layer on the surface of the pre-melted intermediate coating, and the powder micro-morphology is shown in Figure 3

[0096] Step six: copper plate surface strengthened wear-resistant layer laser cladding

[0097] The continuous Nd:YAG laser is used for laser cladding process of the strengthened wear-resistant layer, and the specific process parameters are as follows: laser power 3500KW, spot diameter 2mm, protective gas flow 20L / min, scanning interval 1mm, scanning speed 4mm / s, powder feeding speed 2r / min, and the powder is the strengthened wear-resistant layer powder prepared in step five. The slower scanning speed and larger laser power are used for full-surface cladding of the strengthened layer, which can ensure the full melting of the strengthened layer powder and obtain a certain thickness and uniform organization of the strengthened wear-resistant cladding layer. After machining and grinding the surface, it can be used for continuous casting conditions.

[0098] Specifically, the mass fraction of the metal powder and the binder in step one is as follows: the metal powder accounts for 85%, and the binder accounts for 15%.

[0099] Specifically, the metal powder in step one is pure Ni powder for laser cladding.

[0100] Specifically, the particle size range of the metal powder in step one is 53-150μm, and the purity is more than 99.5%.

[0101] Specifically, the binder in step one is polyvinyl alcohol aqueous solution, and the solute mass fraction is 5%.

[0102] Specifically, the mold in step three is made of chromium-zirconium copper, and the grade is C18150.

[0103] Specifically, the intermediate coating in step three which can be directly used for laser cladding on the surface of the copper plate has a height of 0.2mm, so the height of the mold is slightly higher than that of the copper plate by 0.2mm. The scraper device is placed above the mold, with a distance of 0.2mm from the surface of the copper plate, and the movement direction is horizontal. During the movement, the device keeps uniform and stable operation without shaking or movement failure.

[0104] ​Specifically, the reinforcing wear-resistant layer base powder in step five is spherical Ni60A and pure Co powder with a purity of 99.5% or above and a particle size range of 53-150 μm.

[0105] Specifically, the reinforcing phase ceramic particles in step five are WC with a purity of 99.5% or above and a particle size of about 0.5 μm, in irregular shape.

[0106] Specifically, the reinforcing wear-resistant layer composite powder raw material mass fraction ratio in step five is: Ni60A powder accounts for 70%, pure Co powder accounts for 20%, and nano WC ceramic particles accounts for 10%.

[0107] Further, the high-temperature wear resistance of the laser cladding reinforced wear-resistant layer cladding sample is tested at 300°C, and the wear resistance of the Ni-Co coating prepared by the mainstream electroplating process is compared. Figure 4 As shown in the results, the high-temperature wear resistance of the reinforced wear-resistant layer is significantly better than that of the coating prepared by the conventional electroplating process.

[0108] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and all should be covered in the scope of the claims of the present application.

Claims

1. A method for preparing a laser cladding reinforced wear-resistant coating for a continuous casting mold copper plate, characterized in that: The following steps are involved: Preparation of intermediate coating: weigh metal powder and binder and pre-mix them to obtain a colloidal mixture; Intermediate coating homogenization treatment: the pre-mixed colloidal mixture is subjected to acoustic resonance treatment; Post-treatment of the intermediate coating: the colloidal mixture after the acoustic resonance treatment is evenly applied on the copper plate of the crystallizer to form an intermediate coating on the surface of the copper plate of the crystallizer, and then dried; Laser pre-cladding of the intermediate coating on the copper plate surface: Laser pre-cladding of the intermediate coating on the surface of the crystallizer copper plate; Preparation of the reinforced wear-resistant layer powder: weighing one or more of nickel-based powder, cobalt powder and reinforcing ceramic particles, and mixing the powders to obtain the reinforced wear-resistant layer powder; Laser cladding of the copper plate surface strengthening wear-resistant layer: using the strengthening wear-resistant layer powder as raw material, laser cladding is performed on the intermediate coating on the surface of the crystallizer copper plate after laser pre-cladding to obtain the laser cladding strengthening wear-resistant coating for the continuous casting crystallizer copper plate.

2. The preparation method according to claim 1, characterized in that The intermediate coating preparation step also includes weighing a surfactant and premixing it with the metal powder and the binder, with the mass fraction ratio being: 80-95% metal powder, 4-20% binder, and 0-3% surfactant.

3. The preparation method according to claim 2, characterized in that The metal powder comprises at least one of pure Ni, NiCo alloy, Ni60, Inconel 718, Inconel 625, GH1140, GH4169, GH2132, GH3030, GH3044 and GH3128; the particle size ranges from 15 to 150 μm, the morphology is spherical or nearly spherical, and the purity is above 99%; The binder comprises at least one of polyvinyl alcohol, polyvinyl acetate, polyvinyl acetal, acrylate, polyvinyl chloride, sodium silicate, potassium silicate, copper oxide, aluminum phosphate, magnesium phosphate and solutions of the above substances; The surfactant includes at least one of titanate, stearate, silicate and silane.

4. The preparation method according to claim 1, characterized in that In the intermediate coating preparation step, a V-type mixer is used for pre-mixing, with a mixing speed of 50 rpm to 400 rpm and a mixing time of 0.5 to 9 h.

5. The preparation method according to claim 1, characterized in that In the intermediate coating homogenization treatment step, an acoustic resonance device is used to perform acoustic resonance treatment, and the acoustic resonance treatment includes high-frequency mixing: frequency 90 Hz, acceleration 40-100 g, and mixing time 1 min-10 min; and Medium and low frequency mixing: frequency 60Hz, acceleration 40-100g, mixing time 5min-60min.

6. The preparation method according to claim 1, characterized in that In the intermediate coating post-treatment step, the colloidal mixture after acoustic resonance treatment is evenly spread on the crystallizer copper plate using a mold and a scraper device, with a spreading height of 0.2mm-0.5mm, and then placed in a vacuum drying oven for drying at a temperature of 50-80°C for 3-6 hours.

7. The preparation method according to claim 1, characterized in that In the step of laser pre-cladding of the intermediate coating on the surface of the copper plate, a continuous Nd:YAG laser is used for pre-cladding, with a laser power of 0.5-1.5 kW, a spot diameter of 2-5 mm, a shielding gas flow rate of 15-25 L / min, a scanning interval of 1-3 mm, a scanning speed of 10-30 mm / s, and no powder feeding; After pre-cladding is completed, the surface is cleaned and polished.

8. The preparation method according to claim 1, characterized in that In the step of preparing the powder for the reinforced wear-resistant layer, the mass fraction ratio of the raw materials of the composite powder for the reinforced wear-resistant layer is: 70-100% nickel-based powder, 0-30% cobalt powder, and 0-10% reinforcing phase ceramic particles; The cobalt powder is spherical pure cobalt powder with a purity of more than 99% and a particle size range of 20-150 μm; The reinforcing phase ceramic particles include at least one of TiC, B4C, WC, TiB2, TiB and ZrB, with an average particle size of 0.5-5 μm; Using an acoustic resonance device to perform powder mixing, the powder mixing process includes high-frequency mixing: frequency 90 Hz, acceleration 30-100g, mixing time 1 min-10 min; and Medium and low frequency mixing: frequency 60Hz, acceleration 30-100g, mixing time 5min-60min; After the powder mixing process is completed, put it into the drying box to keep it dry.

9. The preparation method according to claim 1, characterized in that In the step of laser cladding the copper plate surface strengthening wear-resistant layer, a continuous Nd:YAG laser is used for cladding, with a laser power of 3-6 kW, a spot diameter of 2-5 mm, a shielding gas flow rate of 15-25 L / min, a scanning spacing of 1-3 mm, a scanning speed of 2-6 mm / s, and a powder feeding speed of 1.5-2.5 r / min; After the laser cladding is completed, the surface is machined and smoothed to obtain a laser cladding reinforced wear-resistant coating for the continuous casting crystallizer copper plate.

10. The preparation method according to any one of claims 1 to 9, characterized in that The material of the crystallizer copper plate is chromium-zirconium copper, silver-copper, red copper or brass.

Images