Metal Coating Material and Its Preparation Method

Abstract

The present invention discloses a metal coating material and a preparation method thereof, relating to the technical field of material preparation. The method includes: performing surface roughening treatment on a substrate and cleaning the substrate after the surface roughening treatment to obtain a well-cleaned substrate; obtaining the installation parameters of a spraying device and installing the well-cleaned substrate on the spraying device according to the installation parameters, where the installation parameters include the spraying distance; obtaining the spraying parameters of the spraying device and adjusting the device parameters of the spraying device according to the spraying parameters, where the spraying parameters include the oxygen-fuel ratio, chamber filling rate, nitrogen dilution amount, and powder feeding rate; feeding preset powder into the adjusted spraying device and using the spraying device to spray the preset powder on the substrate to form a metal coating. This preparation method can greatly reduce the content of impurities in the coating material, making the content of impurities in the prepared metal coating very low and the purity relatively high. At the same time, the coating has high density and good bonding.

Description

Technical Field

[0001] The present invention relates to the technical field of material preparation, and particularly to a metal coating material and a preparation method thereof. Background Art

[0002] In the prior art, the preparation of metal coatings is generally achieved by explosion spraying. Explosion spraying is a technique that uses the energy generated after the detonation of a fuel / oxygen mixed gas to heat and accelerate powder particles and impact the surface of the substrate material to deposit and form a coating material. The coatings prepared by the explosion spraying method have significant advantages such as a dense structure and high bonding strength.

[0003] There are many parameters affecting the coating quality in the explosion spraying technology. For different materials, the corresponding appropriate spraying parameters vary greatly. Therefore, it is often very difficult to find the most suitable spraying parameters for different powder materials. In addition, the products of gas explosion contain a large number of gas molecules or active particles composed of elements such as carbon, oxygen, and hydrogen. They are extremely likely to react with chemically active powder materials (such as metal powders, alloy powders, composite material powders, etc.) to form oxides, carbides, or be introduced into the deposited coating to form doping and alloying, resulting in a decrease in the purity of the coating material. Therefore, the coating materials prepared in the prior art have the disadvantages of relatively high impurity content and low purity. Summary of the Invention

[0004] The present invention provides a metal coating material and a preparation method thereof. This preparation method can greatly reduce the content of impurities such as oxygen and carbon in the coating material, making the impurity content in the prepared metal coating very low and the purity relatively high. At the same time, the coating structure is dense and the bonding is good.

[0005] The present invention provides a method for preparing a metal coating. The method includes: performing surface roughening treatment on a substrate and cleaning the substrate after the surface roughening treatment to obtain a cleaned substrate; obtaining the installation parameters of a spraying device and installing the cleaned substrate on the spraying device according to the installation parameters. The installation parameters include the spraying distance, and the range of the spraying distance is 50 - 100 mm; obtaining the spraying parameters of the spraying device and adjusting the device parameters of the spraying device according to the spraying parameters. The spraying parameters include the oxygen-fuel ratio, chamber filling rate, nitrogen dilution amount, and powder feeding rate. Among them, the range of the oxygen-fuel ratio is 1.20 - 1.50, the range of the chamber filling rate is 30% - 50%, the range of the nitrogen dilution amount is 4.00% - 8.00%, and the range of the powder feeding rate is 40 - 80 mg; feeding a preset powder into the adjusted spraying device, and using the spraying device to spray the preset powder on the substrate to form a metal coating.

[0006] In the preparation method of the present invention, the cleaned substrate is installed on the spraying device according to the installation parameters, and the installation parameters include the spraying distance, including: adjusting the distance between the nozzle of the spraying device and the surface of the substrate according to the spraying distance to determine the installation position of the substrate; installing the cleaned substrate on the spraying device at the installation position.

[0007] In the preparation method of the present invention, the spraying device includes a gas throttle valve and a powder feeder, and the regulation of the device parameters and gas input parameters of the spraying device according to the spraying parameters includes: determining the powder feeding parameters and working mode of the spraying device according to the spraying parameters; regulating the device parameters of the gas throttle valve corresponding to each gas according to the working mode; regulating the device parameters of the powder feeder according to the powder feeding parameters.

[0008] In the preparation method of the present invention, the regulation of the device parameters of the gas throttle valve corresponding to each gas according to the working mode includes: regulating the aperture and opening duration of the gas throttle valve corresponding to the fuel gas according to the working mode; regulating the aperture and opening duration of the gas throttle valve corresponding to oxygen; and regulating the aperture and opening duration of the gas throttle valve corresponding to nitrogen.

[0009] In the preparation method of the present invention, the regulation of the device parameters of the powder feeder according to the powder feeding parameters includes: regulating the volume of the slider groove corresponding to the powder feeder according to the powder feeding parameters.

[0010] In the preparation method of the present invention, the spraying device includes an explosive spraying device.

[0011] In the preparation method of the present invention, spraying the preset powder on the substrate by using the spraying device to form a metal coating includes: spraying the preset powder on the substrate by using the explosive spraying device to form a metal coating;

[0012] Spraying the preset powder on the substrate by using the explosive spraying device to form a metal coating includes: sending oxygen and fuel gas with a preset ratio from the corresponding gas supply port of the explosive spraying device to the combustion explosion chamber of the water-cooled spray gun; feeding the preset powder into the combustion explosion chamber through the powder feeder so that the preset powder floats in the mixed gas of oxygen and fuel gas, and igniting and burning in the mixed gas by a spark plug to generate heat to reach the melting state, and spraying the preset powder onto the surface of the substrate at a high speed by means of the high pressure generated by the explosion shock wave to form a metal coating.

[0013] In the preparation method of the present invention, the step of feeding the preset powder into the adjusted spraying device includes: feeding the preset powder into the spraying device by a preset powder feeding method, where the powder feeding method includes in-gun powder feeding or coaxial powder feeding.

[0014] In the preparation method of the present invention, the preset powder includes iron powder, copper powder, aluminum powder or steel powder.

[0015] On the other hand, the present invention also provides a metal coating material, which is a coating material prepared by using the above preparation method.

[0016] An embodiment of the present invention provides a metal coating material and a preparation method thereof. The method includes surface roughening the substrate and cleaning the substrate after surface roughening to obtain a cleaned substrate; obtaining the installation parameters of the spraying device and installing the cleaned substrate on the spraying device according to the installation parameters, where the installation parameters include the spraying distance and the spraying distance is controlled within the range of 50 - 100 mm; obtaining the spraying parameters of the spraying device and adjusting the device parameters and gas input parameters of the spraying device according to the spraying parameters, where the spraying parameters include the oxygen-fuel ratio, chamber filling rate, nitrogen dilution amount and powder feeding rate. Among them, the oxygen-fuel ratio is controlled within the range of 1.20 - 1.50, the chamber filling rate is controlled within the range of 30% - 50%, the nitrogen dilution amount is controlled within the range of 4.00% - 8.00%, and the powder feeding rate is controlled within the range of 40 - 80 mg; finally, feeding the preset powder into the adjusted spraying device and using the spraying device to spray the preset powder on the substrate to form a metal coating. This can ensure that the temperature of the powder during spraying does not exceed the melting point and the spraying speed is high enough. On the basis of forming a metal coating with high density and high bonding strength, the possibility of powder oxidation and carbonization is reduced, thereby greatly reducing the content of impurities such as oxygen and carbon in the coating material, making the impurity content in the prepared metal coating very low and the purity relatively high. Description of the Drawings

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic flow chart of a method for preparing a metal coating provided by an embodiment of the present invention;

[0019] Figure 2It is a schematic structural diagram of an explosion spraying device provided by an embodiment of the present invention;

[0020] Figure 3 It is a schematic diagram of an SEM result provided by an embodiment of the present invention;

[0021] Figure 4 It is a schematic diagram of an XRD result provided by an embodiment of the present invention;

[0022] Figure 5 It is a schematic diagram of the results of an oxygen, nitrogen, hydrogen analyzer and a carbon, sulfur analyzer provided by an embodiment of the present invention. Detailed implementation manners

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] It should be understood that when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0025] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in this specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0026] It should be further understood that the term " / and" used in this specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the related listed items, and includes these combinations.

[0027] Next, in conjunction with the accompanying drawings, some implementation manners of the present application will be described in detail. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0028] Existing detonation spraying technology generally requires that the temperature of the detonation products be high enough when preparing coatings, so that the powder can be heated to a molten or semi-molten state, that is, the temperature of the detonation products should at least reach the melting point of the powder used for spraying. For metal coatings prepared by such a method, especially pure metal coatings with active chemical properties such as pure iron, they are very easy to react with oxygen in the air, or active substances such as oxygen and carbon in the detonation products to form impurities such as oxides and carbides. It is very difficult to reduce the content of these impurities in the coating by adjusting the spraying parameters, because these parameters affect each other, and the influence mechanism on the coating quality is also very complex. It is difficult to ensure both the coating quality (density, bonding strength, etc.) and a very low impurity content in the coating.

[0029] Moreover, there are many parameters affecting the coating quality in detonation spraying (DS) technology. For different materials, the corresponding appropriate spraying parameters vary greatly. Therefore, it is often very difficult to find the most suitable spraying parameters for different powder materials. In addition, the products of gas detonation contain a large number of gas molecules or active particles composed of elements such as carbon, oxygen, and hydrogen. They are extremely easy to react with powder materials with active chemical properties (such as metal powders, alloy powders, composite material powders, etc.) to form oxides and carbides, or introduce doping and alloying in the deposited coating, resulting in a decrease in the purity of the coating material. Therefore, the coating materials prepared by the existing technology have the disadvantages of high impurity content and low purity.

[0030] Among them, the five key parameters including the oxygen / fuel ratio (OFR), barrel filling ratio (BFR), nitrogen volume in the charge gases (NV), powders feeding rate (PFR), and spraying distance (SD) all affect the quality of the metal coating prepared by detonation spraying. To solve the problem of how to use DS to prepare a pure iron coating with high density and low oxygen and carbon impurity content, this application gives the appropriate adjustment ranges of these five parameters. When these parameters are within their respective ranges, a low-temperature working mode of detonation spraying can be achieved, so that the impurity content in the prepared metal coating is very low and the purity is relatively high.

[0031] To solve the above problems, please refer to Figure 1 , Figure 1FIG. 0 is a schematic flow chart of a method for preparing a metal coating provided by an embodiment of the present invention. This preparation method can ensure that the powder temperature does not exceed the melting point during spraying and the spraying speed is high enough. On the basis of being able to form a metal coating with high density and high bonding strength, it reduces the possibility of powder oxidation and carbonization, thereby greatly reducing the content of impurities such as oxygen and carbon in the coating material, making the impurity content in the prepared metal coating very low and the purity relatively high.

[0032] As Figure 1 shown, the method for preparing the metal coating includes steps S101 to S104.

[0033] S101. Perform surface roughening treatment on the substrate and clean the substrate after the surface roughening treatment to obtain a cleaned substrate.

[0034] Among them, as Figure 2 shown, the substrate 10 can be made of materials such as low activation ferritic / martensitic steel (RAFM, CLAM steel, etc.), oxide dispersion strengthened steel (ODS steel), etc.

[0035] In some embodiments, the surface roughening treatment method includes but is not limited to sandblasting treatment, threading treatment, knurling treatment, and electro-roughening treatment.

[0036] Exemplarily, the surface of the substrate 10 can be sandblasted with white corundum abrasive with a mesh size of 80 - 250 to make its surface rough, then ultrasonically cleaned with absolute ethanol and ultrapure water for 5 - 10 minutes, and then dried with dry compressed air and fixed on the spraying equipment for subsequent spraying treatment.

[0037] S102. Obtain the installation parameters of the spraying equipment and install the cleaned substrate on the spraying equipment according to the installation parameters. The installation parameters include the spraying distance, and the range of the spraying distance is 50 - 100 mm.

[0038] Among them, as Figure 2 shown, the installation parameters can include the spraying distance, and the spraying distance is the distance between the spray gun nozzle 11 of the spraying equipment and the surface of the substrate 10. The spraying distance is an important parameter affecting the quality of the metal coating, and the spraying distance must be within a certain range to ensure the deposition of a high-quality coating.

[0039] Specifically, within a certain range of the spraying distance, the change in the temperature of the heated powder has little effect, but the velocity of the powder gradually increases with the increase of the spraying distance until it approaches a certain velocity upper limit value. Through experiments, it is known that when the spraying distance range is controlled to be 50 - 100 mm, the spraying effect is optimal. Based on forming a metal coating with high density and high bonding strength, the content ratio of the active components of oxygen and carbon in the explosion products can be made close to the just-neutralized level, greatly reducing the possibility of the powder being oxidized and carbonized, thereby significantly reducing the content of oxide and carbide impurities in the metal coating.

[0040] In some embodiments, according to the spraying distance, the distance between the spray gun nozzle 11 of the spraying device and the surface of the substrate 10 is adjusted to determine the installation position of the substrate 10; the cleaned substrate 10 is installed on the spraying device at the installation position. Thus, the installation position of the substrate 10 can be accurately determined and installed at this installation position, so that the spraying distance is within the optimal range, and thus the spraying effect is optimal.

[0041] Specifically, the distance between the spray gun nozzle 11 of the spraying device and the surface of the substrate 10 can be first determined to determine the installation position of the substrate 10 and the spraying device. The previously cleaned substrate 10 is installed on the spraying device at the installation position, so that the spraying distance is within the optimal range and the spraying effect is optimal.

[0042] S103. Obtain the spraying parameters of the spraying device and adjust the device parameters of the spraying device according to the spraying parameters. The spraying parameters include the oxygen-fuel ratio, chamber filling rate, nitrogen dilution amount, and powder feeding rate.

[0043] Among them, the range of the oxygen-fuel ratio is 1.20 - 1.50, the range of the chamber filling rate is 30% - 50%, the range of the nitrogen dilution amount is 4.00% - 8.00%, and the range of the powder feeding rate is 40 - 80 mg; the device parameters of the spraying device can specifically include the device parameters of the gas throttle valve 14 and the powder feeder 12. It should be noted that through the combined design of these parameters, the preparation of the explosion spraying coating in the "low-temperature mode" is realized, that is, while the temperature of the explosion products is relatively low (not exceeding the melting point of the powder), a high acceleration effect is generated on the powder, so that most of the powder impacts the surface of the substrate at a very high speed in a non-molten state to form a coating. Thus, the content of impurities such as oxygen and carbon in the coating material can be greatly reduced, and the content of impurities in the prepared metal coating is very low and the purity is relatively high.

[0044] Among them, the spraying parameters include the oxygen-fuel ratio, chamber filling rate, nitrogen dilution amount, and powder feeding rate. The oxygen-fuel ratio is the ratio of oxygen to fuel gas; the chamber filling rate refers to the ratio of the total volume of fuel gas, oxygen, and nitrogen used for dilution injected into the explosion chamber before detonation to the chamber volume; the nitrogen dilution amount refers to the proportion of the volume of nitrogen gas injected into the explosion chamber before detonation in the total volume of injected gas. Since the working mode of explosion spraying is pulsed, the powder feeding rate refers to the powder feeding amount in a single-pulse explosion spraying.

[0045] Specifically, to ensure that the gas in the barrel of the spraying equipment can be normally detonated, the oxygen-fuel ratio needs to be within a certain range. Appropriately reducing the oxygen-fuel ratio within this range can reduce the oxygen impurity content in the formed metal coating to a certain extent, but too low an oxygen-fuel ratio will lead to an increase in the carbon impurity content in the metal coating. Through experiments, it is known that when the oxygen-fuel ratio is controlled within the range of 1.20 - 1.50, the spraying effect is optimal. Using the OFR value within this range can ensure the normal detonation of the gas, and at the same time, the oxygen and carbon contents in the metal coating are very low.

[0046] Specifically, within the range of the detonable chamber filling rate, the higher the chamber filling rate value, the higher the energy generated by the explosion, that is, the higher the temperature and speed at which the powder can be heated and accelerated; conversely, the powder temperature and speed will both decrease. Therefore, the value of the chamber filling rate can control the working mode of the spraying equipment to a certain extent, specifically including the low-temperature mode, normal mode, and overheat mode. Through experiments, it is known that when the value of the chamber filling rate is controlled within the range of 30% - 50%, the spraying effect is optimal. Using the BFR value within this range can ensure that the working mode of the spraying equipment is the low-temperature mode.

[0047] Specifically, within the range of the detonable nitrogen dilution amount, increasing the nitrogen dilution amount value can appropriately reduce the temperature of the explosion products, that is, the maximum temperature value to which the powder can be heated will decrease, but the effect of accelerating the powder will not be significantly weakened. Through experiments, it is known that when the value of the nitrogen dilution amount is controlled within the range of 4.00% - 8.00%, at this time, the NV value can moderately cooperate with the BFR value to control the working mode of the spraying equipment and at the same time reduce the impact on the powder speed.

[0048] Specifically, after other parameters are fixed, the energy generated by each explosion is certain. At this time, the powder feeding rate must be within a certain range to ensure that these portions of powder can be just heated and accelerated to the appropriate state, so as to deposit and form a high-quality coating. Through experiments, it is known that when the powder feeding rate is controlled within the range of 40 - 80 mg, the maximum temperature and speed at which the powder is heated and accelerated can be appropriately reduced, but the deposition efficiency of the coating (the thickness of the deposited coating per unit time) can be appropriately increased.

[0049] In some embodiments, the spraying device includes a gas throttle valve and a powder feeder 12. According to the spraying parameters, the powder feeding parameters and working mode of the spraying device are determined; according to the working mode, the device parameters of the gas throttle valves 14 corresponding to each gas are regulated; according to the powder feeding parameters, the device parameters of the powder feeder 12 are regulated. Thus, the device parameters of the gas throttle valves 14 and the powder feeder 12 can be accurately determined, so as to control each spraying parameter of the spraying device within an optimal range, thereby greatly reducing the contents of impurities such as oxygen and carbon in the coating material, and making the impurity content in the prepared metal coating very low and the purity relatively high.

[0050] Among them, each gas corresponds to a gas throttle valve. For example, the channel for inputting oxygen has a gas throttle valve for controlling the input of oxygen, the channel for inputting nitrogen has a gas throttle valve for controlling the input of nitrogen, and the channel for inputting fuel gas has a gas throttle valve for controlling the input of fuel gas; the powder feeder 12 is used to feed powder into the spraying device. The fuel gas can be a gas such as hydrogen.

[0051] Specifically, the device parameters of the powder feeder 12 can be adjusted through the powder feeding parameters. The device parameters of the powder feeder 12 can specifically include the groove volume of the slider 13 and the model of the slider 13, etc.; the device parameters of the gas throttle valve 14 can be adjusted through the working mode, which can specifically include a low-temperature mode, a normal mode, a superheat mode, etc.; the device parameters of the gas throttle valve 14 can specifically include the aperture diameter and opening duration of the gas throttle valves corresponding to each gas.

[0052] Exemplarily, according to the optimal spraying parameters provided by the present application, the powder feeding parameters and working mode of the spraying device are determined; according to the working mode being the low-temperature mode, the device parameters of the gas throttle valves 14 corresponding to each gas (oxygen, nitrogen, and hydrogen) are regulated; at the same time, according to the powder feeding parameters, the device parameters of the powder feeder 12 are also regulated, so as to control each spraying parameter of the spraying device within an optimal range, thereby greatly reducing the contents of impurities such as oxygen and carbon in the coating material, and making the impurity content in the prepared metal coating very low and the purity relatively high.

[0053] In some embodiments, according to the working mode, the aperture diameter and opening duration of the gas throttle valve 14 corresponding to the fuel gas are regulated; the aperture diameter and opening duration of the gas throttle valve 14 corresponding to oxygen are regulated; and, the aperture diameter and opening duration of the gas throttle valve 14 corresponding to nitrogen are regulated. Thus, by controlling the aperture diameter and opening duration of the gas throttle valves 14 corresponding to each gas, each spraying parameter of the spraying device can be controlled within an optimal range, thereby greatly reducing the contents of impurities such as oxygen and carbon in the coating material, and making the impurity content in the prepared metal coating very low and the purity relatively high.

[0054] Specifically, airflow throttling valves with different apertures can be used, and the injection duration of the airflow can be controlled by controlling the opening duration of the airflow throttling valve.

[0055] Exemplarily, when the apertures of the gas throttling valves 14 for the fuel gas and oxygen are the same, the injection times of the fuel gas and oxygen can be controlled to achieve a predetermined OFR value; alternatively, when the injection times of the fuel gas and oxygen are the same, the gas throttling valves 14 corresponding to the fuel gas and oxygen respectively use gas throttling valves 14 with specific apertures, and a predetermined OFR value can also be achieved.

[0056] Exemplarily, when the aperture of the gas throttling valve 14 for the fuel gas and oxygen is larger and the gas injection time is longer, the BFR value is larger; conversely, the BFR value is smaller.

[0057] Exemplarily, gas throttling valves 14 corresponding to nitrogen with different apertures are used, and the injection duration of nitrogen is controlled. Generally, a very small amount of nitrogen is injected after the fuel gas and oxygen are injected. By controlling the aperture and gas injection time of the gas throttling valve 14 corresponding to the nitrogen pipeline, a predetermined NV value can be achieved.

[0058] In some embodiments, according to the powder feeding parameters, the groove volume of the slider 13 corresponding to the powder feeder 12 is adjusted. Thus, by controlling the groove volume and model of the slider 13 corresponding to the powder feeder 12, the powder feeding efficiency of the spraying device can be controlled within an optimal range, so that the maximum temperature and speed at which the powder is heated and accelerated can be appropriately reduced, but the deposition efficiency of the coating (the thickness of the deposited coating per unit time) can be appropriately increased.

[0059] Specifically, by using sliders 13 of the powder feeder 12 with different groove volumes, the amount of powder injected for each explosion pulse can be controlled.

[0060] Exemplarily, the groove volume of the slider 13 can be adjusted by using sliders 13 of different models, and the amount of powder injected for each explosion pulse can be controlled. Among them, the smaller the groove volume, the lower the NV value; conversely, the higher the NV value.

[0061] S104. Feed the preset powder into the adjusted spraying device, and use the spraying device to spray the preset powder on the substrate to form a metal coating.

[0062] Among them, the preset powder includes powders such as iron powder, copper powder, aluminum powder or steel powder, etc., so as to prepare corresponding metal coatings.

[0063] It should be noted that the corresponding installation parameters and spraying parameters can be determined according to the characteristics of different types of powders, such as melting point, density, particle size, etc.

[0064] Exemplarily, if the metal coating material and its preparation method provided by the present application are used to prepare a pure iron coating, the range of the spraying distance can be reduced to 60 - 80 mm; the range of the oxygen-fuel ratio can be reduced to 1.20 - 1.40, the range of the chamber filling rate can be reduced to 30% - 45%, the range of the nitrogen dilution amount can be reduced to 5.00% - 7.50%, and the range of the powder feeding rate can be reduced to 45 - 65 mg.

[0065] Specifically, after adjusting the equipment parameters of the spraying equipment, the preset powder is fed into the adjusted spraying equipment, and the preset powder is sprayed on the substrate 10 by the spraying equipment to form a metal coating.

[0066] In some embodiments, the spraying equipment includes an explosion spraying equipment.

[0067] Among them, explosion spraying is a technology that uses the energy generated after the detonation of a fuel / oxygen mixed gas to heat and accelerate powder particles and impact the surface of the substrate 10 material to deposit and form a coating material. The coating prepared by the explosion spraying method has significant advantages such as a dense structure and high bonding strength.

[0068] In one embodiment, since the agglomerated mixed powder is prone to adsorb moisture in the air, before feeding the preset powder into the spraying equipment, it further includes: placing the preset powder in an oven and baking it at a constant temperature of 100°C for 4 hours.

[0069] Specifically, before adding the preset powder into the powder feeder 12, it is baked in an oven at a constant temperature of 100°C for 4 hours.

[0070] In some embodiments, the preset powder is fed into the spraying equipment by a preset powder feeding method.

[0071] Among them, the powder feeding method includes in-gun powder feeding method or coaxial powder feeding method. Preferably, considering factors such as cost and adaptability, the preset powder feeding method generally adopts the in-gun powder feeding method.

[0072] In some embodiments, the preset powder is sprayed on the substrate 10 by the explosion spraying equipment to form a metal coating.

[0073] Specifically, oxygen and fuel gas with a preset ratio are sent from the corresponding gas supply port of the explosion spraying equipment to the combustion explosion chamber of the water-cooled spray gun; the preset powder is fed into the combustion explosion chamber through the powder feeder 12 so that the preset powder floats in the mixed gas of oxygen and fuel gas, and is ignited by a spark plug and burns and explodes in the mixed gas to generate heat to reach the molten state, and the preset powder is sprayed onto the surface of the substrate 10 at high speed by the high pressure generated by the explosion shock wave to form a metal coating.

[0074] Exemplarily, oxygen and acetylene with a preset ratio are sent from the gas supply port of the explosion spraying device to the combustion explosion chamber of the water-cooled spray gun; a preset powder (such as iron powder) is sent into the combustion explosion chamber through the powder feeder 12 so that the iron powder floats in the mixed gas of oxygen and acetylene, and is ignited by a spark plug and burns and explodes in the mixed gas to generate heat to reach a molten state, and the iron powder is sprayed onto the surface of the substrate 10 at a high speed by means of the high pressure generated by the explosion shock wave to form a metal coating.

[0075] In one embodiment, as Figure 2 shown, based on Figure 2 the explosion spraying device provided in

[0076] (1) Intake air: Mix explosive gases at the intake port and input the mixed gas into the spray gun. The explosive gases used are mainly oxygen and acetylene.

[0077] (2) Powder feeding: Use the protective gas nitrogen to send the preset powder into the spray gun to form a cloud of powder mist in a certain area in the barrel of the spray gun; the powder feeding methods are divided into two types: axial powder feeding and radial powder feeding, mainly axial powder feeding.

[0078] (3) Ignition: Transmit an ignition signal with a given frequency into the explosion chamber of the barrel. The explosion ignites the combustible gas. The explosion lasts for about a few milliseconds, generating a high temperature of up to about 3500 °C and an air flow of about 1500 m / s. The high-temperature and high-speed air flow acts on the preset powder particles. The particles are softened by heating and shoot towards the surface of the substrate 10 at an initial speed of 600 - 1000 m / s. When the powder impacts the surface of the substrate 10, the kinetic energy is converted into heat energy, and the temperature of the powder particles rises during the impact, even reaching its melting point. Therefore, a surface coating with extremely high density and high bonding strength can be formed.

[0079] (4) Remove residual gas and residual powder: Input the protective gas into the chamber. The protective gas uses nitrogen to remove the remaining gas and powder in the barrel and prepare for the next cycle. The above steps are repeated in the next cycle.

[0080] It should be noted that the spraying device can be adjusted according to the spraying parameters and installation parameters, and a better effect can be obtained for the metal coating prepared by using the adjusted spraying device. Of course, in other embodiments, other parameters can also be used.

[0081] The preparation method of the metal coating provided by this application utilizes a reasonable combination of various spraying parameters in explosion spraying, achieving the preparation of an explosion spraying coating in the "low-temperature mode", that is: while the temperature of the explosion products is relatively low (not exceeding the melting point of the powder), a high acceleration effect is exerted on the powder, so that the vast majority of the powder impacts the surface of the substrate 10 at an extremely high speed in a non-molten state to form a coating. At the same time, the content ratio of the active components of oxygen and carbon in the explosion products under this parameter is at a level close to just being neutralized, greatly reducing the possibility of the powder being oxidized and carbonized, thereby greatly reducing the content of oxide and carbide impurities in the coating. As Figure 3 shown, from the SEM result diagram, the porosity in the metal coating is very low, and the porosity ≤ 0.8% is obtained through image method measurement; in addition, the interface between the coating and the substrate has completely achieved metallurgical bonding, and the existence of the interface can hardly be seen at a higher magnification, confirming the good bonding between the metal coating and the substrate.

[0082] As Figure 4 shown, from the XRD result diagram, the metal coating has the same diffraction peaks as the powder, and the presence of other impurities cannot be detected. As Figure 5 shown, it is obtained from the experiment that according to the results of the oxygen, nitrogen, hydrogen analyzer and the carbon, sulfur analyzer, it is confirmed that the content of oxygen, carbon or sulfur in the coating is at a very low level. Therefore, it can be verified that according to the installation parameters and spraying parameters of the spraying equipment provided by this application, on the basis of being able to form a metal coating with high density and high bonding strength, the possibility of the powder being oxidized and carbonized is reduced, thereby greatly reducing the content of impurities such as oxygen and carbon in the coating material, making the impurity content in the prepared metal coating very low and the purity relatively high.

[0083] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for preparing a metal coating, characterized in that, The method includes: Roughening the surface of the substrate and cleaning the roughened substrate to obtain a cleaned substrate; Obtaining the installation parameters of the spraying device and installing the cleaned substrate on the spraying device according to the installation parameters, where the installation parameters include the spraying distance, and the range of the spraying distance is 50 - 100 mm; Obtaining the spraying parameters of the spraying device and adjusting the device parameters of the spraying device according to the spraying parameters; Feeding the preset powder into the adjusted spraying device and using the spraying device to spray the preset powder on the substrate, so that the preset powder impacts on the surface of the substrate in an unmelted state to form a metal coating; the preset powder includes iron powder, copper powder or aluminum powder; The spraying device includes a gas throttle valve and a powder feeder, and adjusting the device parameters of the spraying device according to the spraying parameters includes: Determining the powder feeding parameters and working mode of the spraying device according to the spraying parameters, the working mode is the low-temperature mode, and the low-temperature mode is used to indicate that the temperature of the explosion products is lower than the melting point of the preset powder. The spraying parameters include the oxygen-fuel ratio, chamber filling rate, nitrogen dilution amount and powder feeding rate. Among them, the range of the oxygen-fuel ratio is 1.20 - 1.50, the range of the chamber filling rate is 30% - 50%, the range of the nitrogen dilution amount is 4.00% - 8.00%, and the range of the powder feeding rate is 40 - 80 mg; Adjusting the device parameters of the gas throttle valve corresponding to each gas according to the working mode; Adjusting the device parameters of the powder feeder according to the powder feeding parameters.

2. The preparation method according to claim 1, characterized in that, Installing the cleaned substrate on the spraying device according to the installation parameters, where the installation parameters include the spraying distance, includes: Adjusting the distance between the spray gun nozzle of the spraying device and the surface of the substrate according to the spraying distance to determine the installation position of the substrate; Installing the cleaned substrate on the spraying device at the installation position.

3. The preparation method according to claim 1, characterized in that, Adjusting the device parameters of the gas throttle valve corresponding to each gas according to the working mode includes: Adjusting the aperture and opening duration of the gas throttle valve corresponding to the fuel gas according to the working mode; Adjusting the aperture and opening duration of the gas throttle valve corresponding to oxygen; and, Adjusting the aperture and opening duration of the gas throttle valve corresponding to nitrogen.

4. The preparation method according to claim 1, wherein, Adjusting the device parameters of the powder feeder according to the powder feeding parameters includes: Adjusting the volume of the slider groove corresponding to the powder feeder according to the powder feeding parameters.

5. The preparation method according to claim 1, characterized in that, The spraying device includes an explosion spraying device.

6. The preparation method according to claim 5, characterized in that, Spraying the preset powder on the substrate by using the spraying device to form a metal coating includes: spraying the preset powder on the substrate by using the explosion spraying device to form a metal coating; Spraying the preset powder on the substrate by using the explosion spraying device to form a metal coating includes: Oxygen and fuel gas with a preset ratio are sent from the corresponding gas supply ports of the explosion spraying equipment to the combustion chamber of the water-cooled spray gun; The preset powder is fed into the combustion chamber through a powder feeder so that the preset powder floats in the mixed gas of oxygen and fuel gas, and is ignited by a spark plug and burns and explodes in the mixed gas to generate heat to reach a molten state, and the preset powder is sprayed onto the surface of the substrate at a high speed by means of the high pressure generated by the explosion shock wave to form a metal coating.

7. The preparation method according to claim 1, characterized in that, The feeding of the preset powder into the adjusted spraying equipment includes: The preset powder is fed into the spraying equipment by a preset powder feeding method, wherein the powder feeding method includes in-gun powder feeding or coaxial powder feeding.

8. A metal coating material, characterized in that, The metal coating material is a coating material prepared by using any one of the preparation methods of claims 1 to 7.

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