Method for determining a metal fire-resistant coating material and metal fire-resistant coating

Abstract

The application provides a determination method of a metal combustion-resistant coating material and a metal combustion-resistant coating. In the determination method of the metal combustion-resistant coating material, a characteristic parameter affecting combustion of the coating material is determined based on a combustion threshold value expression of a metal substrate after coating, then measured values of the characteristic parameters of a plurality of candidate coating materials are obtained, and the candidate coating materials with the measured values meeting preset conditions are determined as the metal combustion-resistant coating materials based on an influence relationship between a critical oxygen pressure or a critical temperature and the characteristic parameters (the critical oxygen pressure or the critical temperature increases with increase of a combustion activation energy E of a coating / substrate interface, a thermal conductivity λ, a reaction order n, a coating thickness h, an oxygen diffusion resistance coefficient D, and a coating reaction coefficient Kc). The metal combustion-resistant coating obtained by using the determination method has high combustion thresholds (critical oxygen pressure and critical temperature) and combustion resistance.

Description

Technical Field

[0001] This application relates to the field of metal combustion technology, and in particular to a method for determining a metal fire-resistant coating material and a metal fire-resistant coating. Background Technology

[0002] Under high temperature, high pressure, and alternating load conditions, metallic components are highly flammable, such as aluminum alloy battery casings for new energy vehicles and structural steel for high-rise buildings. Once a fire breaks out, it spreads rapidly, burning the components in a very short time and causing serious damage. Therefore, solving the problem of metal ignition has become a key and challenging aspect of improving the safety performance of components under extreme conditions.

[0003] The main design considerations for existing metal fire-retardant coatings are wear resistance, heat insulation, and oxidation resistance, such as aerogel heat insulation pads for battery casings and intumescent heat insulation coatings for high-rise structural steel. However, after repeated friction, the wear-resistant layer and heat insulation layer will fail, the oxide film will crack and lose its protective properties at high temperatures, and the exposed substrate will not have fire-resistant properties.

[0004] In summary, current research on fire-retardant coatings for metals primarily focuses on improving the oxidation resistance, heat insulation, and wear resistance of coating materials. However, it fails to recognize that metal combustion is not solely determined by these material factors. Rather, it is determined by the combined effects of material factors (composition, size, oxide film characteristics, thermal conductivity, etc.), operating conditions (temperature, flow rate, pressure, etc.), and ignition factors (impact, friction, vibration, etc.) until the system energy reaches an energy threshold. This energy threshold can be characterized by parameters such as temperature, pressure, flow rate, and friction. Therefore, providing a novel design approach for fire-retardant coatings to improve the fire resistance of metal components has become an urgent problem to be solved. Summary of the Invention

[0005] The purpose of this application is to provide a method for determining a metal flame-retardant coating material and a metal flame-retardant coating, so as to improve the flame-retardant performance of metal component materials. The specific technical solution is as follows:

[0006] The first aspect of this application provides a method for determining a metal flame-retardant coating material, which includes the following steps:

[0007] Based on the expression for the combustion threshold value of the metal substrate after coating, characteristic parameters affecting the combustion of the coating material are determined. The expression for the combustion threshold value of the metal substrate after coating is as follows:

[0008]

[0009] In the formula, This indicates the critical value at which the metal matrix will burn. Indicates the heat of reaction. E represents the thermal conductivity, R represents the combustion activation energy at the coating / substrate interface, and T represents the universal gas constant. i The critical temperature (also known as the critical ignition temperature) is represented by r, the total length of the metal substrate after coating is represented by k, the pre-exponential factor is represented by P, the critical oxygen pressure is represented by n, the reaction order is represented by D, the oxygen diffusion resistance coefficient is represented by h, the coating thickness is represented by K, the oxygen adsorption rate on the coating surface is represented by Kc, and the coating reaction coefficient is represented by kc.

[0010] The characteristic parameters include at least one of the following: combustion activation energy E at the coating / substrate interface, thermal conductivity λ, reaction order n, coating thickness h, oxygen diffusion resistance coefficient D, and coating reaction coefficient Kc.

[0011] The characteristic parameters of multiple candidate coating materials are measured, and based on the influence relationship between the critical oxygen pressure or critical temperature and the characteristic parameters, the candidate coating materials whose measured values ​​meet the preset conditions are determined as the metal flame-retardant coating materials; wherein, the influence relationship is: the critical oxygen pressure or critical temperature increases with the increase of the combustion activation energy E, thermal conductivity λ, reaction order n, coating thickness h, oxygen diffusion resistance coefficient D, and coating reaction coefficient Kc at the coating / substrate interface.

[0012] In some embodiments of the first aspect of this application, obtaining the measured values ​​of characteristic parameters of multiple candidate coating materials includes: obtaining the measured values ​​of characteristic parameters of each candidate coating material based on combustion experiments conducted on different candidate coating materials.

[0013] In some embodiments of the first aspect of this application, the preset conditions include: increasing the critical oxygen pressure of the coating material to not less than 0.08 MPa, and / or increasing the critical temperature of the coating material to not less than 70 K. Preferably, the preset conditions include: increasing the critical oxygen pressure of the coating material to not less than 0.08 MPa and increasing the critical temperature of the coating material to not less than 70 K.

[0014] The second aspect of this application provides a metal flame-retardant coating, wherein the coating material is determined by the aforementioned method for determining metal flame-retardant coating materials.

[0015] In some embodiments of the second aspect of this application, the metal flame-retardant coating material is selected from at least one of chromium-based materials, nickel-based materials, silver-based materials, and gold-based materials.

[0016] In some embodiments of the second aspect of this application, the metal flame-retardant coating is a single-layer structure or a multi-layer composite structure.

[0017] In some embodiments of the second aspect of this application, the single-layer structure metal flame-retardant coating includes at least one of Cr or its alloy, Ni or its alloy, Ag or its alloy, Au or its alloy, Cr-Ni composite material, Cr-Ag composite material, and Cr-Au composite material, and the multi-layer composite structure metal flame-retardant coating includes at least one of Cr-based material layer and Ni-based material layer, Cr-based material layer and Ag-based material layer, and Cr-based material layer and Au-based material layer.

[0018] In some embodiments of the second aspect of this application, the thickness of the metal flame-retardant coating is not less than 50 μm, preferably 50-300 μm.

[0019] In some embodiments of the second aspect of this application, the metal flame-retardant coating is obtained on the surface of a metal substrate by a thermal spraying process or an ion plating deposition process.

[0020] In some embodiments of the second aspect of this application, the metal matrix includes, but is not limited to, titanium, titanium alloy, aluminum, aluminum alloy, magnesium, magnesium alloy, iron, or iron alloy.

[0021] This application provides a method for determining a metal flame-retardant coating material and a metal flame-retardant coating. The method involves determining characteristic parameters affecting the combustion of the coating material based on an expression for the combustion threshold value of the metal substrate after coating. Then, measured values ​​of the characteristic parameters of multiple candidate coating materials are obtained. Based on the influence relationship between the critical oxygen pressure or critical temperature and the characteristic parameters, candidate coating materials whose measured values ​​meet preset conditions are determined as metal flame-retardant coating materials. The influence relationship is as follows: the critical oxygen pressure or critical temperature increases with the increase of the combustion activation energy E, thermal conductivity λ, reaction order n, coating thickness h, oxygen diffusion resistance coefficient D, and coating reaction coefficient Kc at the coating / substrate interface. The metal flame-retardant coating obtained using the method of this application has a high combustion threshold (critical oxygen pressure and critical temperature) and flame-retardant performance, resulting in metal components using this metal flame-retardant coating exhibiting high flame-retardant performance, thereby improving their safety and service life.

[0022] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these accompanying drawings.

[0024] Figure 1The graph shows the relationship between the coating thickness and critical oxygen pressure of the metal flame-retardant coatings in Examples 3, 4, and 5.

[0025] Figure 2 A scanning electron microscope image of the Cr-coated sample from Example 6;

[0026] Figure 3 The image shows the ignition temperature curve of the Cr coating sample with a coating thickness of 100 μm in Example 2. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0028] The first aspect of this application provides a method for determining a metal flame-retardant coating material, the method comprising the following steps:

[0029] S1, based on the expression for the combustion threshold value of the metal substrate after coating, determines the characteristic parameters that affect the combustion of the coating material.

[0030] The expression for the combustion threshold value of the coated metal substrate in this application is as follows:

[0031]

[0032] In the formula, This indicates the critical value at which the metal matrix will burn. Indicates the heat of reaction. E represents the thermal conductivity, R represents the combustion activation energy at the coating / substrate interface, and T represents the universal gas constant. i Here, represents the critical temperature, r represents the total length of the metal substrate after coating, k represents the pre-exponential factor, P represents the critical oxygen pressure, n represents the reaction order, D represents the oxygen diffusion resistance coefficient, h represents the coating thickness, K represents the oxygen adsorption rate on the coating surface, and Kc represents the coating reaction coefficient; The critical characteristic parameter representing the ignition of the metal matrix is ​​only related to the size of the metal matrix. The right side of the formula combines the heat generation effect under the overall reaction conditions, which is mainly related to the critical oxygen pressure (P).

[0033] It can be represented as:

[0034] (1)

[0035] In equation (1), a, b, and c represent the length, width, and height of the metal matrix, respectively.

[0036] Specifically, the expression for the combustion threshold value of the metal substrate after coating in this application is established as follows:

[0037] Based on the "Prediction Method for Ignition Conditions of Metal Combustion" disclosed in CN202210619221.1, a mathematical model for the combustion threshold value of coatings is established by introducing parameters of different types of coatings:

[0038] (2)

[0039] In equation (2), This represents the energy accumulated during the combustion of the metal substrate after coating. This represents the energy transferred from the coating system to the metal substrate during the combustion process. This indicates the heat generated by the reaction of the metal substrate after coating.

[0040] Furthermore, This represents the energy accumulated during the process of a specific unit of the coating rising to its critical temperature due to the heat generated by the reaction of the metal substrate system itself and the combined effect of heat conduction. It can be represented as:

[0041] (3)

[0042] In equation (3), ρ represents the density of the metal substrate, c represents the specific heat capacity of the metal substrate, V represents the volume of the metal substrate, T represents the ambient temperature of the metal substrate system after coating, and at ignition, it represents the critical temperature or ignition temperature (as mentioned above). i (Consistent), t represents the time it takes for the sample to heat up to the ignition temperature.

[0043] This indicates the energy transferred from the coating system to the metal substrate under a temperature gradient during the coating combustion process. It can be represented as:

[0044] (4)

[0045] In equation (4), λ represents the thermal conductivity. This represents the Laplacian operator, where T represents the ambient temperature of the metal substrate system after coating, and at ignition, it represents the critical temperature or ignition temperature (as mentioned above). i Consistent).

[0046] It is related to the degree of heat accumulation before the system ignites, that is, it depends on the heat generation rate of the metal substrate system before ignition after coating and the heat of reaction during combustion. Oxygen absorption rate and the hindering effect of different coating materials on oxygen diffusion reaction.

[0047] Furthermore, the relationship between oxygen flux at the interface between the metal substrate and the coating is established, assuming that: 1) the coating is a homogeneous system; 2) oxygen diffusion is a one-dimensional steady-state diffusion that conforms to Fick's first diffusion law, and when only oxygen diffusion occurs, the change in oxygen content is considered to follow a linear law; 3) the gap effect at the interface between the coating and the metal substrate is ignored, and it is assumed that all oxygen at the interface participates in the reaction and heat generation.

[0048] Furthermore, when the coating does not react with oxygen but only hinders oxygen diffusion, according to Fick's first law of diffusion, we have:

[0049] (5)

[0050] Therefore, when the coating does not react with oxygen, the oxygen concentration at the coating / substrate interface is:

[0051] (6)

[0052] In equations (5)-(6), K represents the adsorption rate of oxygen on the coating surface, C0 represents the initial oxygen content, D represents the oxygen diffusion resistance coefficient, h represents the coating thickness, k represents the reaction heat generation rate coefficient at the coating / substrate interface, also known as the pre-exponential factor, which is a constant determined by the nature of the reaction, and C1 represents the oxygen content at the coating / substrate interface.

[0053] Furthermore, when the coating reacts with oxygen, it consumes oxygen (reaction inhibition) and hinders oxygen diffusion (diffusion inhibition). Assuming that the "reaction inhibition" is fully completed during oxygen exchange to the coating surface, the oxygen content flowing to the coating / substrate interface is dominated solely by the "diffusion inhibition" effect. Therefore, the oxygen flux conservation relationship can be established as follows:

[0054] Reaction inhibition effect:

[0055] (7)

[0056] Diffusion inhibition effect:

[0057] (8)

[0058] From equations (7) and (8), we can obtain:

[0059] (9)

[0060] In equations (7)-(9), K represents the adsorption rate of oxygen on the coating surface, and Kc represents the coating reaction coefficient. The oxygen content on the coating surface after the reaction inhibition is completed is represented by C0, C2, D, h, and k.

[0061] Furthermore, The different types of coatings mentioned above can then be represented as follows:

[0062] A1. When the coating does not react with oxygen (considering only diffusion inhibition):

[0063] (10)

[0064] A2. When the coating reacts with oxygen (considering both reaction inhibition and diffusion inhibition):

[0065] (11)

[0066] Furthermore, the following expressions for the combustion threshold values ​​of metal substrates after different types of coatings are established (for the specific derivation process, please refer to "A Prediction Method for Ignition Conditions of Metal Combustion" disclosed in Publication No. CN202210619221.1):

[0067] B1. When the coating does not react with oxygen:

[0068] (12)

[0069] B2. When the coating reacts with oxygen:

[0070] (13)

[0071] In equations (10)-(13), This indicates the heat generated by the reaction of the metal substrate after coating. Let λ represent the heat of reaction, E represent the thermal conductivity, E represent the combustion activation energy at the coating / substrate interface, r represent the total length of the metal substrate after coating, k represent the pre-exponential factor, P represent the critical oxygen pressure, n represent the reaction order, R represent the universal gas constant, and T represent the reaction heat. i C1 represents the oxygen content at the coating / substrate interface, and T represents the ambient temperature of the metal substrate system after coating. At ignition, T represents the critical temperature or ignition temperature (as mentioned above). i (Consistent), h represents the coating thickness, K represents the oxygen adsorption rate on the coating surface, D represents the oxygen diffusion resistance coefficient, C2 represents the oxygen content diffused to the coating / substrate interface, and Kc represents the coating reaction coefficient. This indicates the critical value at which the metal matrix will burn.

[0072] Equation (13) above is the expression for the combustion threshold value of the metal substrate after coating in this application.

[0073] After establishing the expression for the combustion threshold value of the metal substrate after coating, characteristic parameters affecting the combustion of the metal flame-retardant coating material can be determined based on this expression. These characteristic parameters include at least one of the following: combustion activation energy E at the coating / substrate interface, thermal conductivity λ, reaction order n, coating thickness h, oxygen diffusion resistance coefficient D, and coating reaction coefficient Kc. Specifically, the combustion activation energy E at the coating / substrate interface refers to the minimum energy required for a molecular combustion reaction; the thermal conductivity λ refers to the heat transferred through the coating / substrate interface per unit time; the reaction order n refers to the sum of the reactant concentration exponents during combustion; the oxygen diffusion resistance coefficient D refers to the diffusion flux of oxygen per unit area per unit time in the coating; and the coating reaction coefficient Kc refers to the oxygen consumption per unit area per unit time in the reaction with the coating material.

[0074] S2, obtain the measured values ​​of characteristic parameters of multiple candidate coating materials, and based on the influence relationship between critical oxygen pressure or critical temperature and characteristic parameters, determine the candidate coating materials whose measured values ​​meet the preset conditions as metal flame-retardant coating materials.

[0075] The relationship between the critical oxygen pressure or critical temperature and the characteristic parameters in this application is as follows: the critical oxygen pressure or critical temperature increases with the increase of the combustion activation energy E, thermal conductivity λ, reaction order n, coating thickness h, oxygen diffusion resistance coefficient D, and coating reaction coefficient Kc at the coating / substrate interface.

[0076] The inventors discovered that, for the expression of the combustion threshold value of the coated metal substrate, let , f1 and f2 represent coating characteristic parameter factors. It can be seen that f1 and f2 are related to the critical oxygen pressure P and the critical temperature T. i The following relationship exists: For a coated metal substrate of a fixed size, If the product of f1 and f2 remains constant, the smaller the product, the higher the critical oxygen pressure P and critical temperature T for combustion. i The higher the value, the better. Based on the above relationship, when the coating thickness is the same, the reaction rate and heat flux density at the coating / substrate interface can be reduced by increasing the active reaction between the coating and oxygen (i.e., reducing the aforementioned coating characteristic parameter factor f2 value), thereby increasing the critical oxygen pressure P and critical temperature T for combustion. i Table 1 shows the characteristic parameter factors of different materials as coatings. It can be seen that compared with the metal substrate Ti or the existing aero-engine coating materials ZrO2 or NiCrAl, the f1f2 values ​​of coating materials Au, Ni, Ag, and Cr are significantly reduced. Therefore, Au, Ni, Ag, and Cr can all be used as candidate coating materials.

[0077] Table 1 Characteristic parameter factors of coatings for different materials

[0078]

[0079] Note: In Table 1, " / " indicates that the material or parameter does not exist.

[0080] In some embodiments of the first aspect of this application, obtaining the measured values ​​of characteristic parameters of multiple candidate coating materials includes: obtaining the measured values ​​of characteristic parameters of each candidate coating material based on combustion experiments conducted on different candidate coating materials. Characteristic parameters obtainable through combustion experiments include the combustion activation energy E or reaction order n at the coating / substrate interface.

[0081] In this application, obtaining the measured values ​​of characteristic parameters for multiple candidate coating materials also includes: obtaining the measured values ​​of characteristic parameters for each candidate coating material based on published literature. Characteristic parameters obtainable from published literature include thermal conductivity λ, oxygen diffusion resistance coefficient D, or coating reactivity coefficient Kc.

[0082] In this application, during a combustion experiment on a metal coating sample, the sample is fixed to a combustion device, the combustion atmosphere is adjusted, and the sample is heated until combustion occurs. This application does not impose any particular limitation on the method of heating the metal coating sample, as long as it achieves the purpose of this invention. For example, the heating method can be resistance wire heating, flame heating, or a high-temperature plasma torch. This application also does not impose any particular limitation on the heating rate of the metal coating sample, as long as it achieves the purpose of this invention. For example, the heating rate can be 200℃ / min-600℃ / min.

[0083] In some embodiments of the first aspect of this application, the preset conditions include: increasing the critical oxygen pressure of the coating material to not less than 0.08 MPa, and / or increasing the critical temperature of the coating material to not less than 70 K.

[0084] The second aspect of this application provides a metal flame-retardant coating, wherein the coating material is determined by the aforementioned method for determining metal flame-retardant coating materials.

[0085] In some embodiments of the second aspect of this application, the metal flame-retardant coating material is selected from at least one of chromium-based materials, nickel-based materials, silver-based materials, and gold-based materials.

[0086] In some embodiments of the second aspect of this application, the metal flame-retardant coating is a single-layer structure or a multi-layer composite structure.

[0087] In some embodiments of the second aspect of this application, the single-layer structure metal flame-retardant coating includes at least one of Cr or its alloy, Ni or its alloy, Ag or its alloy, Au or its alloy, Cr-Ni composite material, Cr-Ag composite material, and Cr-Au composite material, and the multi-layer composite structure metal flame-retardant coating includes at least one of Cr-based material layer and Ni-based material layer, Cr-based material layer and Ag-based material layer, and Cr-based material layer and Au-based material layer.

[0088] In some embodiments of the second aspect of this application, the thickness of the metal flame-retardant coating is not less than 50 μm, preferably 50-300 μm.

[0089] In some embodiments of the second aspect of this application, the metal flame-retardant coating is obtained on the surface of a metal substrate by a thermal spraying process or an ion plating deposition process.

[0090] In some embodiments of the second aspect of this application, the metal matrix includes, but is not limited to, titanium, titanium alloys, aluminum, aluminum alloys, magnesium, magnesium alloys, iron, or iron alloys. In this application, the titanium alloy refers to an alloy metal made of titanium and other metals; there is no particular limitation on the other metals, as long as they achieve the purpose of this application. For example, the titanium alloy includes, but is not limited to, aero-engine materials such as TC4, TC11, TC17, or Ti2AlNb. In this application, the aluminum alloy refers to an alloy metal made of aluminum and other metals; there is no particular limitation on the other metals, as long as they achieve the purpose of this application. For example, the aluminum alloy includes, but is not limited to, 2024 aluminum alloy, 6061 aluminum alloy, or 7075 aluminum alloy. In this application, the magnesium alloy... Magnesium alloys refer to alloys made of magnesium and other metals. There is no particular limitation on the other metals; any metal that achieves the purpose of this application is acceptable. For example, the magnesium alloys include, but are not limited to, Mg-Mn alloys, Mg-Al-Zn-Mn alloys, Mg-Zr alloys, Mg-Zn-Zr alloys, or Mg-Re-Zr alloys. In this application, ferroalloys refer to alloys made of iron and other metals. There is no particular limitation on the other metals; any metal that achieves the purpose of this application is acceptable. For example, the ferroalloys include, but are not limited to, ferrosilicon, ferromanganese, ferrochrome, ferrotungsten, ferromolybdenum, ferrotitanium, ferrovanadium, or ferroboron.

[0091] The present application provides a method for determining a metal flame-resistant coating material and a metal flame-resistant coating. In the method for determining a metal flame-resistant coating material, characteristic parameters affecting the combustion of the coating material are determined based on the expression of the combustion threshold value of the coated metal substrate, then measured values of the characteristic parameters of a plurality of candidate coating materials are obtained, and based on the influence relationship between critical oxygen pressure or critical temperature and the characteristic parameters, a candidate coating material whose measured values meet preset conditions is determined as the metal flame-resistant coating material. The influence relationship is: the critical oxygen pressure or critical temperature increases with the increase of the combustion activation energy E at the coating / substrate interface, thermal conductivity λ, reaction order n, coating thickness h, oxygen diffusion resistance coefficient D, and coating reaction coefficient Kc. The metal flame-resistant coating obtained by the determination method of the present application has a high combustion threshold (critical oxygen pressure and critical temperature) and excellent flame resistance.

[0092] In the present application, focusing on the flame-resistant protection requirements of metals, the inventors propose a protection theory for increasing the combustion threshold value. Based on this, a method for determining a metal flame-resistant coating material that combines diffusion hindrance and reaction hindrance is proposed. By significantly reducing the heat flux density and reaction rate at the coating / substrate interface, the combustion threshold values (critical oxygen pressure and critical temperature) of the metal flame-resistant coating are increased multiple times compared with those of the metal substrate.

[0093] The present application proposes a metal flame-resistant protection theory for the first time based on the principle of increasing the combustion threshold value. Taking titanium alloys for aero-engines as an example, further in-depth research and optimization of this achievement will bring leap-forward development of the flame resistance of titanium alloy blades / casings of aero-engines, and can significantly improve the service stability and safety of aero-engines. The present application not only provides new ideas and new approaches for the flame resistance of metal components under extreme working conditions, but also provides a theoretical basis and technical support for the material selection of flame-resistant protective coatings for related equipment in service / under development, and plays an important role in improving the comprehensive service performance of related equipment in service / under development.

[0094] Test instruments and methods:

[0095] Coating thickness test: A field emission scanning electron microscope is used to photograph the cross-section of the metal coating sample to obtain a field emission scanning electron microscope photograph of the metal coating sample. The coating thickness at three different positions in the photograph is tested, and the average value of the three tests is taken as the metal coating thickness.

[0096] Examples

[0097] Hereinafter, the embodiments of the present application will be described in more detail with reference to Examples and Comparative Examples. Various tests and evaluations are carried out according to the following methods.

[0098] Example 1

[0099] Determination of metal flame-resistant coating material

[0100] <Preparation of Ni Coating Sample>

[0101] A TC17 titanium alloy metal substrate is cut into rod-shaped samples of Φ3.2mm×70mm (i.e., 3.2mm in diameter and 70mm in length), which are then sequentially polished with 240-mesh, 600-mesh and 1000-mesh sandpapers, followed by cleaning (degreasing and deoiling), sandblasting, and pickling. Immediately after the surface of the rod-shaped samples becomes bright, thermal spraying is performed using the coating material Ni, so as to obtain Ni-coated samples with Ni deposition thicknesses of 100μm, 150μm and 200μm respectively.

[0102] <Combustion Performance Test>

[0103] According to the ASTM G124 standard, the Ni-coated samples sprayed with three Ni coatings of different thicknesses are ignited with 0.05g copper wire respectively, and their critical combustion oxygen pressure P and critical temperature T are tested i .

[0104] Example 2

[0105] Determination of Metal Flame-Resistant Coating Material

[0106] <Preparation of Cr-Coated Sample>

[0107] A TC17 titanium alloy metal substrate is cut into rod-shaped samples of Φ3.2mm×70mm, which are then sequentially polished with 240-mesh, 600-mesh and 1000-mesh sandpapers, followed by cleaning (degreasing and deoiling), sandblasting, and pickling. Immediately after the surface of the rod-shaped samples becomes bright, thermal spraying is performed using the coating material Cr, so as to obtain Cr-coated samples with Cr deposition thicknesses of 100μm, 150μm and 200μm respectively.

[0108] <Combustion Performance Test>

[0109] According to the ASTM G124 standard, the Cr-coated samples sprayed with three Cr coatings of different thicknesses are ignited with 0.05g copper wire respectively, and their critical combustion oxygen pressure P and critical temperature T are tested i .

[0110] Example 3

[0111] Determination of Metal Flame-Resistant Coating Material

[0112] <Preparation of Ni-Coated Sample>

[0113] The metal matrix TC17 titanium alloy is cut into rod-shaped samples of Φ3.2mm×70mm, which are then polished sequentially with 240-grit, 600-grit and 1000-grit sandpapers, followed by cleaning (degreasing and deoiling), sandblasting and pickling. Immediately after the surface of the rod-shaped sample becomes bright, ion plating deposition is performed using nickel as the coating material, so as to obtain nickel-coated samples with nickel deposition thicknesses of 100μm, 150μm and 200μm respectively.

[0114] <Combustion Performance Test>

[0115] According to the ASTM G124 standard, the nickel-coated samples with three different thicknesses of nickel coatings are ignited with 0.05g copper wire respectively, and their critical combustion oxygen pressure P and critical temperature T are tested i .

[0116] Example 4

[0117] Determination of Metal Flame-Resistant Coating Materials

[0118] <Preparation of Chromium-Coated Samples>

[0119] The metal matrix TC17 titanium alloy is cut into rod-shaped samples of Φ3.2mm×70mm, which are then polished sequentially with 240-grit, 600-grit and 1000-grit sandpapers, followed by cleaning (degreasing and deoiling), sandblasting and pickling. Immediately after the surface of the rod-shaped sample becomes bright, ion plating deposition is performed using chromium as the coating material, so as to obtain chromium-coated samples with chromium deposition thicknesses of 100μm, 150μm and 200μm respectively.

[0120] <Combustion Performance Test>

[0121] According to the ASTM G124 standard, the chromium-coated samples with three different thicknesses of chromium coatings are ignited with 0.05g copper wire respectively, and their critical combustion oxygen pressure P and critical temperature T are tested i .

[0122] Example 5

[0123] Determination of Metal Flame-Resistant Coating Materials

[0124] <Preparation of Silver-Coated Samples>

[0125] The metal matrix TC17 titanium alloy is cut into rod-shaped samples of Φ3.2mm×70mm, which are then polished sequentially with 240-grit, 600-grit and 1000-grit sandpapers, followed by cleaning (degreasing and deoiling), sandblasting and pickling. Immediately after the surface of the rod-shaped sample becomes bright, ion plating deposition is performed using silver as the coating material, so as to obtain silver-coated samples with silver deposition thicknesses of 100μm, 150μm and 200μm respectively.

[0126] <Combustion Performance Test>

[0127] According to the ASTM G124 standard, the Ag-coated specimens coated with Ag coatings of three different thicknesses are ignited with 0.05 g of copper wire respectively, and their critical combustion oxygen pressure P and critical temperature T are tested i .

[0128] Example 6

[0129] Determination of metal flame-resistant coating material

[0130] <Preparation of Cr-coated specimen>

[0131] The metal substrate TC11 titanium alloy is cut into prismatic samples of 5mm×5mm×70mm, then ground sequentially with 240-grit, 600-grit and 1000-grit sandpapers, followed by cleaning (degreasing, deoiling), sandblasting and pickling. Immediately after the surface of the prismatic sample becomes bright, the coating material Cr is used for thermal spraying, so as to obtain a Cr-coated specimen with a Cr spraying thickness of 100 μm.

[0132] <Combustion performance test>

[0133] According to the ASTM G124 standard, the Cr-coated specimen is ignited with 0.05 g of copper wire, and its critical combustion oxygen pressure P and critical temperature T are tested i .

[0134] Example 7

[0135] Determination of metal flame-resistant coating material

[0136] <Preparation of Ni and Cr double-coated specimen>

[0137] The metal substrate TC11 titanium alloy is cut into prismatic samples of 5mm×5mm×70mm, then ground sequentially with 240-grit, 600-grit and 1000-grit sandpapers, followed by cleaning (degreasing, deoiling), sandblasting and pickling. Immediately after the surface of the prismatic sample becomes bright, the coating material Ni is used for thermal spraying. After the thermal spraying of the coating material Ni is completed, the coating material Cr is thermally sprayed on the Ni coating, so as to obtain a Ni and Cr double-coated specimen with a deposition thickness of 50 μm for both Ni and Cr.

[0138] <Combustion performance test>

[0139] According to the ASTM G124 standard, the Ni and Cr double-coated specimen is ignited with 0.05 g of copper wire, and its critical combustion oxygen pressure P and critical temperature T are tested i .

[0140] Comparative Example 1

[0141] <Preparation of ZrO₂-coated specimen>

[0142] The metal matrix TC11 titanium alloy is cut into prismatic samples of 5mm×5mm×70mm, then polished sequentially with 240-grit, 600-grit and 1000-grit sandpaper, followed by cleaning (degreasing and deoiling), sandblasting and pickling. Immediately after the surface of the prismatic sample becomes bright, thermal spraying is carried out using the coating material ZrO₂, to obtain a ZrO₂ coated sample with a ZrO₂ spray thickness of 200μm.

[0143] <Combustion Performance Test>

[0144] According to the ASTM G124 standard, the ZrO₂ coated sample is ignited with 0.05g copper wire, and its combustion critical oxygen pressure P and critical temperature T are tested i .

[0145] Comparative Example 2

[0146] <Preparation of NiCrAl Coated Sample>

[0147] The metal matrix TC11 titanium alloy is cut into prismatic samples of 5mm×5mm×70mm, then polished sequentially with 240-grit, 600-grit and 1000-grit sandpaper, followed by cleaning (degreasing and deoiling), sandblasting and pickling. Immediately after the surface of the prismatic sample becomes bright, thermal spraying is carried out using the coating material NiCrAl, to obtain a NiCrAl coated sample with a NiCrAl spray thickness of 100μm.

[0148] <Combustion Performance Test>

[0149] According to the ASTM G124 standard, the NiCrAl coated sample is ignited with 0.05g copper wire, and its combustion critical oxygen pressure P and critical temperature T are tested i .

[0150] Comparative Example 3

[0151] <Preparation of Metal Matrix TC17 Titanium Alloy Sample>

[0152] The metal matrix TC17 titanium alloy is cut into rod-shaped samples of Φ3.2mm×70mm, then polished sequentially with 240-grit, 600-grit and 1000-grit sandpaper, followed by cleaning the surface of the rod-shaped samples (degreasing and deoiling), to obtain the metal matrix TC17 titanium alloy sample.

[0153] <Combustion Performance Test>

[0154] According to the ASTM G124 standard, the metal matrix TC17 titanium alloy sample is ignited with 0.05g copper wire, and its combustion critical oxygen pressure P and critical temperature T are tested i .

[0155] Comparative Example 4

[0156] <Preparation of TC11 titanium alloy specimens with metallic matrix>

[0157] The TC11 titanium alloy substrate was cut into prism samples of 5mm×5mm×70mm, and then polished with 240-grit, 600-grit and 1000-grit sandpaper in sequence. The surface of the prism samples was then cleaned (degreasing and oil removal) to obtain the TC11 titanium alloy substrate sample.

[0158] <Combustion Performance Test>

[0159] According to ASTM G124 standard, a TC11 titanium alloy sample with a metallic matrix was ignited with 0.05g of copper wire, and its critical oxygen pressure P and critical temperature T were tested. i .

[0160] Table 2.

[0161]

[0162]

[0163] Note: In Table 2, " / " indicates that the material, process, or parameter does not exist.

[0164] As can be seen from Examples 1-7, compared with Comparative Examples 3-4, the critical oxygen pressure or critical temperature of the coating Ni, Cr, and Ag on the surface of the metal substrate of this application is measured to meet at least one of the following: the critical oxygen pressure is increased by not less than 0.08 MPa and the critical temperature is increased by not less than 70 K. Therefore, the coating materials Ni, Cr, and Ag can all be used as metal flame-retardant coating materials.

[0165] As can be seen from Examples 1-2, 6-7, and Comparative Examples 1-2, when the metal flame-retardant coating material of this application is thermally sprayed onto the surface of a metal substrate, the critical oxygen pressure of the coating material is increased by no less than 0.08 MPa and the critical temperature is increased by no less than 70 K. Under the same thickness, at least one of the increases in critical oxygen pressure and critical temperature is significantly higher than that of ZrO2 or NiCrAl, indicating that the metal flame-retardant coating material of this application has high flame-retardant performance.

[0166] As can be seen from Examples 1-7, by using the metal flame-retardant coating material of this application and controlling the thickness of the metal flame-retardant coating within the range of this application, the critical oxygen pressure and / or critical temperature of the metal flame-retardant coating are significantly improved.

[0167] Figure 1 This is a graph showing the relationship between the coating thickness and critical oxygen pressure of the metal flame-retardant coatings in Examples 3, 4, and 5. Figure 1 It can be seen that by controlling the coating thickness of the metal flame-retardant coating within the range of this application, the critical oxygen pressure of the metal flame-retardant coating is relatively high.

[0168] Figure 2 The image shown is a scanning electron microscope (SEM) image of a Cr-coated sample with a thickness of 100 μm from Example 6. Figure 2 As can be seen, in Example 6, a Cr metal flame-retardant coating was prepared on a metal substrate TC11, and the resulting Cr coating had a uniform thickness distribution.

[0169] Figure 3 This is the ignition temperature curve of the Cr coating sample with a coating thickness of 100 μm in Example 2. Figure 3 It can be seen that the Cr coating sample with a coating thickness of 100 μm in Example 2 has a high critical temperature, as high as 1273.5 K.

[0170] It should be noted that, in this document, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0171] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0172] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. A method for determining a metal flame-retardant coating material, comprising the following steps: Based on the expression for the combustion threshold value of the metal substrate after coating, characteristic parameters affecting the combustion of the coating material are determined. The expression for the combustion threshold value of the metal substrate after coating is as follows: In the formula, This indicates the critical value at which the metal matrix will burn. Indicates the heat of reaction. E represents the thermal conductivity, E represents the combustion activation energy at the coating / substrate interface, R represents the universal gas constant, and T represents the thermal conductivity. i denoted by , r represents the total length of the metal substrate after coating, k represents the pre-exponential factor, P represents the critical oxygen pressure, n represents the reaction order, D represents the oxygen diffusion resistance coefficient, h represents the coating thickness, K represents the oxygen adsorption rate on the coating surface, and Kc represents the coating reaction coefficient. The characteristic parameters include coating thickness h, oxygen diffusion resistance coefficient D, and coating reaction coefficient Kc; The characteristic parameters of multiple candidate coating materials are measured, and based on the influence relationship between the critical oxygen pressure or critical temperature and the characteristic parameters, the candidate coating materials whose measured values ​​meet preset conditions are determined as the metal flame-retardant coating material; wherein, the influence relationship is: Let , For a metal substrate of fixed size after coating, If the product of f1 and f2 remains constant, the smaller the product, the higher the critical oxygen pressure P and critical temperature T for combustion. i The higher; The preset conditions include: the critical oxygen pressure of the coating material is increased by not less than 0.08 MPa, and / or the critical temperature of the coating material is increased by not less than 70 K.

2. The method according to claim 1, wherein, The determination of characteristic parameters of multiple candidate coating materials includes: obtaining the determination of characteristic parameters of each candidate coating material based on combustion experiments on different candidate coating materials.

3. The method according to claim 1, wherein, The metal flame-retardant coating material is selected from at least one of chromium-based materials, nickel-based materials, silver-based materials, and gold-based materials.

4. The method according to claim 1, wherein, The metal flame-retardant coating obtained from the metal flame-retardant coating material determined by the method is a single-layer structure or a multi-layer composite structure. The single-layer structure metal flame-retardant coating includes at least one of Cr or its alloy, Ni or its alloy, Ag or its alloy, Au or its alloy, Cr-Ni composite material, Cr-Ag composite material, and Cr-Au composite material. The multi-layer composite structure metal flame-retardant coating includes at least one of Cr-based material layer and Ni-based material layer, Cr-based material layer and Ag-based material layer, and Cr-based material layer and Au-based material layer.

5. The method according to claim 4, wherein, The thickness of the metal flame-retardant coating is not less than 50 μm.

6. The method according to claim 5, wherein, The thickness of the metal flame-retardant coating is 50-300 μm.

7. The method according to claim 4, wherein, The fire-resistant metal coating is obtained on the surface of the metal substrate by thermal spraying or ion plating deposition.

8. The method according to claim 7, wherein, The metal matrix includes titanium, titanium alloy, aluminum, aluminum alloy, magnesium, magnesium alloy, iron, or iron alloy.

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