Cracking furnace tube coating material composition and cracking furnace tube coating and method for producing the same

Abstract

The present application provides a pyrolysis furnace tube coating material composition and a pyrolysis furnace tube coating and a preparation method thereof. The coating material composition comprises: a first coating material and a second coating material; the first coating material comprises the following components: a catalytically active component, a complexing agent, a buffer and a dispersing agent; and the second coating material is a liquid slurry or a solid particle mixture. The preparation method of the coating comprises: pretreating a substrate surface; loading the first coating material on the pretreated substrate surface, and forming a first coating after atmosphere stabilization treatment; loading the second coating material on the surface of the first coating, and obtaining the coating after high-temperature hot permeation. The pyrolysis furnace tube coating prepared by the coating material composition of the present application has a higher dispersion degree of the catalytically active element, and the catalytically active element is relatively stable; in the repeated use process, the migration phenomenon of the overall elements in the coating is less, and the element loss is lower.

Description

TECHNICAL FIELD

[0001] The present application relates to a pyrolysis furnace tube coating material composition and a pyrolysis furnace tube coating and a preparation method thereof, and belongs to the technical field of olefin production in petrochemical industry. BACKGROUND

[0002] Low-carbon olefins such as ethylene, propylene and butadiene are the most basic chemical raw materials in petrochemical production process. The production capacity of ethylene has been regarded as one of the symbols of the development level of petrochemical industry. As the main production method of ethylene at present, steam cracking often needs to make hydrocarbon raw materials undergo thermal cracking at a high temperature of 750-875 ℃ to generate low-carbon olefins. In order to meet the temperature conditions required by thermal cracking, the material of the steam cracking furnace tube is often selected to be chromium-nickel alloy which has excellent high-temperature resistance. However, under high-temperature conditions, iron and nickel atoms in the alloy will migrate to the outer surface of the substrate, and then enrich on the surface of the furnace tube and act as catalytic active centers, accelerating the deposition of coke on the cracking furnace tube. With the continuous accumulation of coke, on the one hand, the inner diameter of the furnace tube will be reduced, the flow state of the raw material gas in the tube will change, the cracking furnace raw material processing capacity will decrease, and the ethylene production capacity will be adversely affected; on the other hand, due to the large thermal resistance of the coke layer, the heat transfer efficiency of the cracking furnace tube will be reduced, and the operating energy consumption of the cracking furnace will be increased. Generally, an industrial cracking furnace often needs to be shut down for coke removal after running for 30-60 days, and the cracking furnace tube often needs to be put back into production after 48 hours or even longer time of coke removal process, which greatly limits the operating efficiency of the cracking furnace.

[0003] The cracking furnace tube coating technology is the most effective means to inhibit coking in the cracking furnace at present. This technology mainly prepares one or more layers of coating on the inner surface of the cracking furnace tube by physical or chemical methods. These coatings can not only play a shielding role for the catalytic coking active elements such as iron and nickel in the furnace tube substrate, but also reduce the corrosion of the cracking furnace tube caused by carburization in the ethylene production process. This technology can effectively inhibit coking in the cracking furnace tube, greatly improve the operating cycle of the cracking furnace, and the reduction of coke generation on the inner surface of the cracking furnace tube can further reduce the operating energy consumption of the cracking furnace.

[0004] At present, various coating technologies have been developed in the field. These coating technologies mostly use inert coatings, mainly play a shielding role for the iron and nickel elements in the furnace tube substrate, and prevent the generation of catalytic coking to obtain good coking inhibition performance of the cracking furnace tube. However, these coating technologies are mostly difficult to effectively inhibit free radical coking and condensation coking generated in the cracking process. In order to obtain better coking inhibition effect, researchers have proposed a catalytic coating technology. This technology introduces catalytically active elements into the coating. These catalytically active elements can catalytically convert the free radical coking and condensation coking generated in the cracking process into gaseous carbon monoxide and carbon dioxide. The application of this coating technology can greatly reduce the generation of coke in the cracking process, and further prolong the operating cycle of the cracking furnace.

[0005] CN112708445A discloses a pyrolysis apparatus. The reactor inner wall of this apparatus comprises a substrate, a metal layer, a first catalytic coating, and a second catalytic coating. The first catalytic coating comprises a MnxCr composition. 3-x The O4 manganese chromium oxide complex, the second catalytic coating comprises a perovskite material with a composition of AMO3 and / or a composition of (Na2O). y Na2[Al2Si2O8] is a triclinic nepheline-like substance; wherein A is an alkaline earth metal element, and M is selected from at least one of Group IIIB and Group IVB elements. The specific preparation steps of the coating are as follows: (1) the metal powder mixture is coated onto the substrate surface of the pyrolysis device, and the metal powder mixture is cured under vacuum or inert atmosphere to form a metal layer on the substrate surface of the pyrolysis device; (2) heat treatment is performed under low oxygen partial pressure atmosphere and high temperature conditions to form a first catalytic coating on the surface of the metal layer; (3) a second catalytic coating is prepared on the first catalytic coating. The metal layer, the first catalytic coating and the second catalytic coating are all prepared by vapor deposition. The prepared coating can reduce asphalt coking and free radical coking during the pyrolysis process. Under the condition that the olefin yield in the pyrolysis product remains basically unchanged, the coking during the pyrolysis process is reduced to the greatest extent possible. However, the coating slurry used in this technology only employs metal salts and silica-alumina sol. During slurry preparation, the dispersion of metal ions in the system is difficult to guarantee. This prevents the metal elements from being highly dispersed on the substrate surface during subsequent slurry deposition, thus limiting the coating's ability to inhibit coking. Furthermore, the coating prepared by this technology has a multi-layered structure, making the preparation process relatively complex. Additionally, this technical solution does not explore the overall stability and mechanical strength of the coating.

[0006] CN105885486A discloses a composite coating for inhibiting coking of furnace tubes and a preparation method thereof. The main components of the composite coating are BaCeO3 powder and silica sol. The preparation method of the coating formed by the composite coating is mainly by mixing BaCeO3 powder, silica sol and water in a certain proportion to form a slurry, and then coating on the surface of the substrate, and then high-temperature baking to form a coating for inhibiting coking. The BaCeO3 powder in the coating plays a role in inhibiting coking and the solid particle size is 1-3 microns. Applied to a high-pressure thermal cracking device, a hydrocarbon fuel cracking experiment was conducted on the coating, and the results showed that the inhibition rate of the furnace tube loaded with the coating on the carbon deposition reached 56.5% compared with the blank tube. Scanning electron microscopy showed that the coating was dense, the reaction tube was completely filled, the coating structure was more compact after the cracking experiment, and the overall morphology was maintained intact. Although the composite coating has good thermal conductivity and high coking inhibition rate, the BaCeO3 powder prepared is micron-sized particles, so the sintering phenomenon of BaCeO3 particles in the coating will be more serious under high temperature conditions, which limits the coking inhibition effect of the coating to some extent.

[0007] CN102899067B discloses a cracking furnace tube. The cracking furnace tube comprises a cracking furnace tube substrate, and an inert coating attached to the inner wall surface of the cracking furnace tube substrate. The inert coating is a coating capable of preventing coke from contacting the cracking furnace tube substrate and not reacting with cracking raw materials and cracking products, and has a porous structure with an average pore radius of 0.5-15 nm. An active catalytic layer can also be attached to the surface of the inert coating. The inert coating contains silicon dioxide and / or a first metal oxide, and the metal in the first metal oxide is selected from one or more of aluminum, titanium, zirconium, manganese, chromium, lanthanum and magnesium. The active catalytic layer contains a second metal active component, and the metal in the second metal active component is selected from one or more of lithium, sodium, potassium, rubidium, calcium, strontium, barium, molybdenum, cobalt, nickel, iron, copper, cerium and praseodymium. The presence of the second metal active component enables the coating to catalyze the reaction of coke and water vapor. The preparation method of the coating mainly comprises the following steps: (1) using acetone and deionized water to ultrasonically clean the surface of the substrate; (2) preparing an inert coating slurry, and applying the slurry on the surface of the cracking furnace tube substrate by the dipping method, and obtaining the inert coating by high-temperature calcination; (3) preparing an active element salt solution, and loading the active element on the surface of the inert coating by the dipping method, and obtaining the cracking furnace tube with the coating by high-temperature calcination. Although the coating prepared by the method has good anti-coking performance, the active elements are loaded by the dipping method, and the active elements have obvious agglomeration among each other, and the dispersion degree of the active elements is not high. And the subsequent high-temperature heat treatment process will further promote the mutual agglomeration of the elements, which makes the bonding force between the catalytically active layer and the substrate weak, and the catalytically active elements cannot achieve the best catalytic coke conversion efficiency. On the other hand, the method does not study the stability of the prepared coating during repeated use.

[0008] CN103861662B discloses an anti-coking catalyst coating comprising an alumina barrier layer. The coating is a double-layer structure comprising a catalyst layer and an alumina barrier layer, wherein the preparation method of the alumina barrier layer mainly comprises pre-plating aluminum on the surface of the metal substrate, and then performing high-temperature oxidation treatment on the sample. The main function of the alumina barrier layer is to inhibit the outward migration of the catalytic coking elements inside the substrate, and to prevent the enrichment of the catalytic coking elements on the surface of the coating. The catalyst layer mainly comprises BaCe x Zr (1-x)O3 perovskite compound, the perovskite compound is prepared by solid powder roasting method. The main function of the catalyst layer is to catalyze the coke formed in the thermal cracking process of heavy oil into gas such as CO or CO2. The fatigue test of the anti-coking catalyst coating for 200 hours and the simulation cracking test show that the oxidant coating has good anti-coking performance. The anti-coking catalyst coating prepared by the method has good anti-coking performance and service life. However, the solid powder roasting method is used to prepare the catalyst BaCe x Zr (1-x) O3 perovskite compound, the perovskite compound is prepared by solid powder roasting method. The main function of the catalyst layer is to catalyze the coke formed in the thermal cracking process of heavy oil into gas such as CO or CO2. The fatigue test of the anti-coking catalyst coating for 200 hours and the simulation cracking test show that the oxidant coating has good anti-coking performance. The anti-coking catalyst coating prepared by the method has good anti-coking performance and service life. However, the solid powder roasting method is used to prepare the catalyst BaCe

[0009] CN1546609A discloses a method for inhibiting and slowing down the coking of ethylene cracking furnace tube. The method comprises the following steps: (1) using the mixed gas containing H2, N2 and trace amounts of NH3, H2O and O2 generated after the decomposition of liquid ammonia as reducing gas to treat the atmosphere of the furnace tube, and cooling the furnace tube after the treatment; (2) mixing the prepared alloy powder and binder into slurry, coating the slurry on the surface of the furnace tube after the atmosphere treatment, drying and curing, and then placing in a heating furnace for high-temperature diffusion treatment, cooling the furnace tube after the treatment, and removing the excess alloy powder coating on the surface of the furnace tube to form an alloy layer capable of inhibiting and slowing down the coking on the surface of the furnace tube. The alloy powder used in the technology is composed of aluminum, silicon, chromium, rare earth, catalyst and dispersant, and the catalyst is mainly ammonium chloride, sodium fluoride or cryolite. The alloy layer prepared by the technology has a thickness of more than 100 microns and has good coking inhibition effect. The binder used in the technology is mainly edible gelatin and polyvinyl alcohol. Although the coating has good coking inhibition performance, the highest reduction of coking amount can reach 90%, but the uneven mixing of elements in the slurry during the preparation process will cause great differences in the distribution of elements in different coating areas, resulting in different coking inhibition performance in different areas of the coating and different amounts of coke deposition. At the same time, the uneven heating of the coating surface will cause the coating structure to be easily damaged by thermal shock.

[0010] CN101724827A discloses a method for reducing coking of ethylene cracking furnace tube and improving ethylene selectivity. The method comprises the following steps: (1) injecting a pretreatment solution containing ceramic elements and active component elements of catalytic cracking catalyst into the cracking furnace with a carrier gas at the front end of the cracking reaction temperature, carrying out vapor deposition at 500-1000°C; wherein the ceramic elements are mainly Si, Al, Ca, B and other elements, the catalytically active elements are mainly Ag, Cr, Cu, Ti and other elements, and the solvent of the pretreatment solution is ethanol solution; (2) after vapor deposition, passivation treatment is carried out on the metal oxide deposited on the inner wall of the furnace tube in an atmosphere of carrier gas mainly composed of inert gas at 700-1100°C to form a coating. The coating is tested for its coking inhibition performance using industrial naphtha as cracking raw material, and the results show that the coating can reduce the deposition of more than 80% of coke on the inner wall of the furnace tube, and can increase the volume percentage of ethylene in the product by 4.32%. The coating prepared by the method contains inert ceramic elements and catalytically active elements, and the preparation steps are to load the two elements on the surface of the substrate by one-step method, and then obtain the coating by high-temperature passivation treatment. Although the coating applied in the naphtha cracking reaction can significantly reduce the amount of coke generated, it can be seen from the repeated test data that the amount of coke reduction of the coating prepared by the method decreases from 92.97% to 73.29% during repeated use, and the coking inhibition performance of the coating decreases obviously, indicating that the catalytically active elements in the coating migrate and lose, and the stability of the coating as a whole is poor.

[0011] In summary, in order to make the cracking furnace tube coating have the function of catalyzing the gasification and conversion of coke, the existing technology usually introduces active elements such as Li, Na, K, Ru and Ce into the coating during the preparation of the coating. The conventional introduction method is to disperse the inert element components and active element components in a solvent to form a slurry, load the above-mentioned elements on the surface of the substrate by coating, vapor deposition, solid powder embedding and other methods, and combine the elements with each other and penetrate into the substrate alloy phase by subsequent high-temperature heat treatment to form the required coating. Although the existing catalytic coating technology has good catalytic and coking inhibition performance in the application process, the active elements in the slurry often agglomerate, making it difficult for the active elements to be highly dispersed on the surface of the substrate, and the coking inhibition performance of different regions of the prepared coating is not the same, so that the coating has different thermal resistance coefficients in different regions due to different amounts of coke deposition during actual use, which easily causes overheating in local regions of the cracking furnace tube, reduces the service life of the coating and the furnace tube. On the other hand, under the environment of high-temperature oxidation and continuous thermal shock, the combination between the coating elements and the substrate is gradually weakened under the joint action of their own migration and high-temperature carburizing, leading to the peeling and falling off of the coating from the surface of the substrate, the destruction of the structure of the coating and the loss of its protection function for the substrate. SUMMARY

[0012] To solve the above technical problems, the present application aims to provide a cracking furnace tube coating material composition, and a cracking furnace tube coating and a preparation method thereof. The cracking furnace tube coating prepared by the coating material composition of the present application has a higher dispersion degree of the catalytically active elements contained in the interior, and the catalytically active elements are more stable, and the migration phenomenon of the overall elements in the coating is less.

[0013] To achieve the above-mentioned purpose, the present application provides, in a first aspect, a cracking furnace tube coating material composition, comprising: a first coating material and a second coating material.

[0014] wherein, based on the total mass of the first coating material being 100%, it comprises the following components: a catalytically active component 10-40%, a complexing agent 2-30%, a buffering agent 5-20%, and a first dispersant 40-70%; the catalytically active component comprises one or a combination of several of a compound of an alkali metal element, a compound of an alkaline earth metal element, a compound of a rare earth metal element, and a compound of a transition metal element.

[0015] The second coating material is a liquid slurry or a solid particle mixture; based on the total mass of the liquid slurry being 100%, it comprises the following components: an inert protective component 10-65%, a fluxing agent 0.1-3.0%, an activator 1.0-5.0%, a filler 20-80%, and a second dispersant in the balance; based on the total mass of the solid particle mixture being 100%, it comprises the following components: an inert protective component 15-60%, a fluxing agent 0.1-2.5%, an activator 1.0-6.0%, and a filler in the balance.

[0016] In the above-mentioned coating material composition, preferably, based on the total mass of the first coating material being 100%, it comprises the following components: a catalytically active component 10-29%, a complexing agent 5-15%, a buffering agent 5-15%, and a first dispersant 40-70%.

[0017] In the above-mentioned coating material composition, preferably, in the components of the first coating material, the alkali metal element comprises one or a combination of several of Li, Na, and K, etc.; the alkaline earth metal element comprises one or a combination of several of Mg, Ca, Sr, and Ba, etc.; the rare earth metal element comprises one or a combination of several of La, Ce, Pr, Nd, and Y, etc.; and the transition metal element comprises one or a combination of several of Co, Mn, Mo, Cu, Zn, V, Ti, Cr, W, Rh, and Hf, etc.

[0018] In the coating material composition described above, preferably, in the component of the first coating material, the complexing agent comprises one or a combination of several of disodium nitrilotriacetate, disodium ethylenediaminetetraacetate, dithizone, 8-hydroxyquinoline, o-phenanthroline, potassium sodium tartrate, and polyphosphate.

[0019] In the coating material composition described above, preferably, in the component of the first coating material, the buffering agent comprises one or a combination of several of ammonium acetate, tris-hydroxymethyl aminomethane, and citrate.

[0020] In the coating material composition described above, preferably, in the component of the first coating material, the first dispersing agent comprises one or a combination of several of deionized water, ethanol, ethylene glycol, acetone, and chloroform.

[0021] In the coating material composition described above, preferably, the first coating material is prepared by at least the following steps: (a) mixing the catalytically active component, the buffering agent, and a part of the first dispersing agent, and after stirring, forming a mixed system; (b) mixing the complexing agent and another part of the first dispersing agent, and obtaining a complexing agent solution; (c) under stirring, adding the complexing agent solution obtained in step (b) to the mixed system obtained in step (a), and after the addition is completed, continuing to stir for a period of time, and obtaining the first coating material.

[0022] In the coating material composition described above, preferably, in terms of the total mass of the liquid slurry being 100%, it comprises the following components: inert protective component 15-60%, fluxing agent 0.1-2.5%, activating agent 1.0-2.0%, filler 24-70%, and the rest is the second dispersing agent.

[0023] In the coating material composition described above, preferably, in terms of the total mass of the solid granular mixture being 100%, it comprises the following components: inert protective component 24-58%, fluxing agent 0.1-2.5%, activating agent 1.1-4.0%, and the rest is the filler.

[0024] In the coating material composition described above, preferably, in the component of the second coating material, the inert protective component comprises one or a combination of several of elemental chromium, elemental silicon, and elemental aluminum.

[0025] In the coating material composition described above, preferably, in the component of the second coating material, the fluxing agent comprises one or a combination of several of chromium fluoride, sodium fluoride, zirconium chloride, and potassium fluoride.

[0026] In the coating material composition described above, preferably, in the component of the second coating material, the activating agent comprises one or a combination of several of ammonium chloride, ammonium fluoride, and ammonium sulfate.

[0027] In the coating material composition described above, preferably, in the component of the second coating material, the filler includes alumina or the like.

[0028] In the coating material composition described above, preferably, in the component of the second coating material, the second dispersant includes one or a combination of several of deionized water, ethanol, ethylene glycol, acetone, chloroform or the like.

[0029] In the cracking furnace tube coating material composition of the present application, the first coating material and the second coating material can be stored separately, and the first coating material and the second coating material are combined to form a coating when the coating is prepared.

[0030] The second aspect of the present application provides a method for preparing a cracking furnace tube coating, which uses the cracking furnace tube coating material composition described above to form a coating, and the method comprises the following steps:

[0031] (1) pretreating the surface of a substrate;

[0032] (2) loading the first coating material on the surface of the pretreated substrate, and then performing atmosphere stabilization treatment to form a first coating;

[0033] (3) loading the second coating material on the surface of the first coating, and then performing high-temperature thermal diffusion to obtain the cracking furnace tube coating.

[0034] In the method described above, preferably, in step (1), the pretreatment of the surface of the substrate includes soaking the substrate in an inorganic acid solution.

[0035] In the method described above, preferably, in step (2), the loading of the first coating material includes one or a combination of several of liquid brushing, atomized spraying, physical vapor deposition, chemical vapor deposition, and soaking or the like.

[0036] In the method described above, preferably, in step (2), the loading amount of the first coating on the surface of the pretreated substrate is 74-370 g / m 2 .

[0037] In the method described above, preferably, in step (2), the atmosphere stabilization treatment includes using a mixture of nitrogen and hydrogen as the stabilization treatment atmosphere, using programmed temperature rising to raise the substrate loaded with the first coating material to the stabilization treatment temperature in the stabilization treatment atmosphere, maintaining the stabilization treatment temperature for a period of time after reaching the stabilization treatment temperature, and completing the atmosphere stabilization treatment.

[0038] In the method described above, preferably, in the atmosphere stabilization treatment of step (2), the stabilization treatment temperature is 500-750°C.

[0039] In the preparation method, preferably, in the atmosphere stabilization treatment of step (2), the time of constant temperature maintenance is 3-7h.

[0040] In the preparation method, preferably, in step (3), the loading mode of the second coating material includes liquid phase brushing or solid powder embedding. Those skilled in the art can understand that when the second coating material is a liquid slurry, liquid phase brushing is used for loading; when the second coating material is a solid particle mixture, solid powder embedding is used for loading.

[0041] In the preparation method, preferably, in step (3), the high-temperature thermal diffusion includes high-temperature heat treatment of the substrate loaded with the second coating material.

[0042] In the preparation method, preferably, in the high-temperature thermal diffusion of step (3), the temperature of the high-temperature heat treatment is 850-1200℃, and the time of constant temperature maintenance is 4-9h.

[0043] In the preparation method, preferably, in step (3), the high-temperature thermal diffusion is carried out in a protective atmosphere, and the protective atmosphere includes nitrogen and / or argon and the like.

[0044] The third aspect of the present application provides a cracking furnace tube coating prepared by the preparation method of the cracking furnace tube coating.

[0045] According to the specific embodiment of the present application, preferably, the thickness of the cracking furnace tube coating is 20-300μm.

[0046] The technical solution of the present application has at least the following beneficial effects:

[0047] The cracking furnace tube coating prepared by the coating material composition of the present application is a ceramic coating. The ceramic coating has the functions of high-temperature protection of the substrate and catalytic gasification conversion of coke generated in the process of hydrocarbon cracking. The ceramic coating has excellent mechanical properties, hot corrosion resistance and sintering resistance. The catalytically active elements contained in the coating have high dispersity, so that the coating has excellent coke inhibition effect in application. At the same time, the catalytically active elements contained in the coating are relatively stable, and the migration of the overall elements in the coating is less and the loss of elements is lower during repeated use. Therefore, the ceramic coating can well inhibit the coking of the cracking furnace tube and improve the service life of the cracking furnace tube. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 SEM photograph of the cross section of the ceramic coating prepared for Example 1.

[0049] Figure 2 Mapping energy spectrum of catalytically active elements on the surface of the ceramic coating prepared for Example 1.

[0050] Figure 3 Mapping energy spectrum of catalytically active elements on the surface of the ceramic coating prepared for Comparative Example 3.

[0051] Figure 4 Distribution of catalytically active elements on the cross-section of the ceramic coating prepared for Example 1.

[0052] Figure 5 Graph of the coking inhibition rate of the coating prepared for Example 1, Example 6, Example 11 and Comparative Example 2 as a function of the use cycle. DETAILED DESCRIPTION

[0053] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present application, the technical solutions of the present application will be described in detail below, but it cannot be understood as limiting the implementable scope of the present application.

[0054] The first aspect of the present application provides a cracking furnace tube coating material composition, which comprises: a first coating material and a second coating material;

[0055] wherein, based on the total mass of the first coating material being 100%, it comprises the following components: a catalytically active component 10-40%, a complexing agent 2-30%, a buffering agent 5-20% and a first dispersant 40-70%; the catalytically active component comprises one or a combination of several of the following: a compound of an alkali metal element, a compound of an alkaline earth metal element, a compound of a rare earth metal element, a compound of a transition metal element;

[0056] The second coating material is a liquid slurry or a solid particle mixture; based on the total mass of the liquid slurry being 100%, it comprises the following components: an inert protective component 10-65%, a fluxing agent 0.1-3.0% (preferably 0.1-2.5%), an activator 1.0-5.0%, a filler 20-80% and a second dispersant in the balance; based on the total mass of the solid particle mixture being 100%, it comprises the following components: an inert protective component 15-60%, a fluxing agent 0.1-2.5%, an activator 1.0-6.0% and a filler in the balance.

[0057] In some specific embodiments of the present application, based on the total mass of the first coating material being 100%, it comprises the following components: a catalytically active component 10-29%, a complexing agent 5-15%, a buffering agent 5-15% and a first dispersant 40-70%.

[0058] In some embodiments of the present application, the alkali metal element comprises one or a combination of Li, Na and K, preferably Li and / or K; the alkaline earth metal element comprises one or a combination of Mg, Ca, Sr and Ba, preferably one or a combination of Mg, Ca and Ba; the rare earth metal element comprises one or a combination of La, Ce, Pr, Nd and Y, preferably one or a combination of La, Ce and Y; and the transition metal element comprises one or a combination of Co, Mn, Mo, Cu, Zn, V, Ti, Cr, W, Rh and Hf, preferably one or a combination of Ti, Cr and W.

[0059] In some embodiments of the present application, the compound of the alkali metal element, the compound of the alkaline earth metal element, the compound of the rare earth metal element and the compound of the transition metal element can comprise a salt compound of the metal element, or an organic compound of the metal element, preferably a salt compound of the metal element, such as nitrate, chloride, etc.

[0060] In some embodiments of the present application, the complexing agent comprises one or a combination of disodium nitrilotriacetate, disodium ethylenediaminetetraacetate, dithizone, 8-hydroxyquinoline, o-phenanthroline, potassium sodium tartrate and polyphosphate, etc.

[0061] In some embodiments of the present application, the buffer comprises one or a combination of ammonium acetate, tris-hydroxymethyl aminomethane and citrate, etc.

[0062] In some embodiments of the present application, the first dispersing agent comprises one or a combination of deionized water, ethanol, ethylene glycol, acetone and chloroform, etc. Preferably, the first dispersing agent comprises deionized water and / or ethanol.

[0063] In some embodiments of the present application, the pH value of the first coating material is 4-9.

[0064] In some embodiments of the present application, the first coating material is prepared by at least the following steps: (a) mixing the catalytically active component, the buffer and a part of the first dispersing agent, and after stirring, a mixed system is formed; (b) mixing the complexing agent and another part of the first dispersing agent to obtain a complexing agent solution; (c) under stirring, the complexing agent solution obtained in step (b) is added dropwise into the mixed system obtained in step (a), and after the dropwise addition is completed, the stirring is continued for a period of time to obtain the first coating material.

[0065] In some embodiments of the present application, the preparation step (a) of the first coating material is carried out under constant temperature, and the constant temperature is 20-50°C, preferably 30-40°C.

[0066] In some embodiments of the present application, the stirring speed in the preparation step (a) of the first coating material is 200-600 rpm, preferably 200-450 rpm.

[0067] In some embodiments of the present application, the concentration of the complexing agent solution in the preparation step (b) of the first coating material is 0.01-1 mol / L, preferably 0.1-1 mol / L.

[0068] In some embodiments of the present application, the dropping speed of the complexing agent solution in the preparation step (c) of the first coating material is 0.1-5 mL / min, preferably 0.5-3 mL / min.

[0069] In some embodiments of the present application, the preparation step (c) of the first coating material is carried out under constant temperature, and the constant temperature is 20-50°C, preferably 30-40°C.

[0070] In some embodiments of the present application, the stirring speed in the preparation step (c) of the first coating material is 200-300 rpm.

[0071] In some embodiments of the present application, the time for continuing stirring after the dropping is completed in the preparation step (c) of the first coating material is 20-75 min.

[0072] The catalytically active component used in the present application includes one of alkali metal elements, alkaline earth metal elements, rare earth metal elements, transition metal elements, or a composite solid solution compound composed of several of these elements. Therefore, the coating provided by the present application has the function of protecting the substrate at high temperature, and also has the function of catalytically gasifying and converting the coke generated in the process of cracking hydrocarbons.

[0073] In the existing catalytic coating technology, the catalytic coating slurry is prepared in advance, and then coated and heat treated at high temperature to form the required coating. In the process of preparing the slurry, the catalytically active components are directly injected, and therefore, whether the slurry is fully mixed and uniform will be an important factor affecting the dispersion of the catalytically active components in the coating. During the mixing process, the catalytically active components often agglomerate into large particles, which reduces the dispersion of the catalytically active components in the coating, and ultimately limits the anti-coking performance of the catalytic coating.

[0074] The present application introduces complexing agent into the first coating material, and adjusts the complexation of the complexing agent to the catalytically active components by controlling the pH value of the first coating material, the temperature of the preparation process, the stirring rate and other conditions, so that the agglomeration among the catalytically active components in the first coating material is effectively reduced.

[0075] In some embodiments of the present application, the liquid slurry includes the following components: inert protective component 15-60%, fluxing agent 0.1-2.5%, activating agent 1.0-2.0%, filler 24-70%, and the rest of the second dispersing agent, based on the total mass of the liquid slurry being 100%.

[0076] In some embodiments of the present application, the solid particle mixture includes the following components: inert protective component 24-58%, fluxing agent 0.1-2.5% (preferably 0.1-2.0%), activating agent 1.1-4.0%, and the rest of the filler, based on the total mass of the solid particle mixture being 100%.

[0077] In some embodiments of the present application, the inert protective component includes one or a combination of elemental chromium, elemental silicon, and elemental aluminum.

[0078] In some embodiments of the present application, the fluxing agent includes one or a combination of chromium fluoride, sodium fluoride, zirconium chloride, and potassium fluoride.

[0079] In some embodiments of the present application, the activating agent includes one or a combination of ammonium chloride, ammonium fluoride, and ammonium sulfate.

[0080] In some embodiments of the present application, the filler includes aluminum oxide.

[0081] In some embodiments of the present application, the particle size of the inert protective component and the filler is 100-350 mesh, respectively.

[0082] In some embodiments of the present application, the second dispersing agent includes one or a combination of deionized water, ethanol, ethylene glycol, acetone, and chloroform. Preferably, the second dispersing agent includes deionized water and / or ethanol.

[0083] In some embodiments of the present application, the second coating material is prepared by stirring the components. Preferably, the stirring time of the components in the preparation of the second coating material is 0.5-10 h.

[0084] The second aspect of the present application provides a preparation method of the cracking furnace tube coating, which forms the coating by using the cracking furnace tube coating material composition described above, and the method includes the following steps:

[0085] (1) pretreating the surface of the substrate;

[0086] (2) loading a first coating material on the surface of the pretreated substrate, and then performing atmosphere stabilization treatment to form a first coating layer;

[0087] (3) loading a second coating material on the surface of the first coating layer, and then performing high-temperature thermal diffusion to obtain the coating layer of the cracking furnace tube.

[0088] In some embodiments of the present application, the substrate is a high-temperature resistant alloy steel, including GH series alloy, NS series alloy, or Incoloy series alloy, etc. Preferably, the GH series alloy, which can specifically include Cr 20 Ni 35 alloy, Cr 20 Ni 30 alloy, Cr 15 Ni 60 alloy, Cr 30 Ni 70 alloy, Cr 20 Ni 80 alloy, Cr 25 Ni 35 alloy, or Cr 25 Ni 20 alloy, etc.

[0089] In some embodiments of the present application, in step (1), the pretreatment of the surface of the substrate includes soaking the substrate in an inorganic acid solution.

[0090] In some embodiments of the present application, in step (1), the inorganic acid includes one or a combination of several of hydrochloric acid, nitric acid, phosphoric acid, and sulfuric acid, preferably including hydrochloric acid and / or nitric acid.

[0091] In some embodiments of the present application, in step (1), the concentration of the inorganic acid solution is 0.01 mol / L to 0.1 mol / L.

[0092] In some embodiments of the present application, in step (1), the soaking time is 10 min to 150 min, preferably 20 min to 120 min.

[0093] In some embodiments of the present application, in step (1), the pre-treatment of the substrate surface further comprises: water washing and drying the substrate after the immersion in the inorganic acid solution. The water washing is to clean the residual inorganic acid on the substrate surface, and the drying is to keep the substrate surface dry. The drying can be vacuum drying, with a vacuum degree of 100-400 Pa, a drying temperature of 40-90°C (preferably 40-80°C), and a drying time of 0.1-5h (preferably 1-5h).

[0094] In some embodiments of the present application, in step (2), the loading of the first coating material comprises one or a combination of liquid brushing, atomized spraying, physical vapor deposition, chemical vapor deposition, and immersion.

[0095] In some embodiments of the present application, in step (2), the loading amount of the first coating on the pre-treated substrate surface is 74-370g / m 2 , preferably 74-300g / m 2 .

[0096] In some embodiments of the present application, in step (2), the atmosphere stabilization treatment comprises: using a mixture of nitrogen and hydrogen as the stabilization treatment atmosphere, and using programmed temperature rising to raise the substrate loaded with the first coating material to a stabilization treatment temperature, and after reaching the stabilization treatment temperature, maintaining the temperature for a period of time to complete the atmosphere stabilization treatment.

[0097] In some embodiments of the present application, in the atmosphere stabilization treatment of step (2), the volume concentration of hydrogen in the mixture of nitrogen and hydrogen is 10-40%, preferably 10-30%.

[0098] In some embodiments of the present application, in the atmosphere stabilization treatment of step (2), the flow rate of the mixture of nitrogen and hydrogen is 10-100mL / min, preferably 30-70mL / min.

[0099] In some embodiments of the present application, in the atmosphere stabilization treatment of step (2), the temperature rising rate of the programmed temperature rising is 5-15°C / min, preferably 5-10°C / min.

[0100] In some embodiments of the present application, in the atmosphere stabilization treatment of step (2), the stabilization treatment temperature is 500-750°C, preferably 500-650°C.

[0101] In some embodiments of the present application, in the atmosphere stabilization treatment of step (2), the temperature maintaining time is 3-7h.

[0102] In the existing coating technology, solvent coating method is often used to introduce catalytically active components. During the coating process, the catalytically active components may agglomerate with each other, resulting in that the prepared coating has limited inhibition of coking performance. In addition, due to repeated high-temperature thermal shock and high-temperature migration of elements, the service life of the existing coating is short, and the catalytically active elements are easy to be lost, so that the inhibition of coking performance of the coating is difficult to maintain at a high level.

[0103] In the coating preparation method of the present application, by performing pickling treatment on the surface of the substrate, defect sites can be constructed on the surface of the substrate, thereby enhancing the bonding of the first coating material to the surface of the substrate. After the first coating material of the present application is loaded on the surface of the substrate, the catalytically active components can be uniformly dispersed on the surface of the substrate. Combined with the stable treatment of the atmosphere, the catalytically active components will be reduced, and at the same time, the complexing agent will be decomposed under the action of high temperature for the subsequent high-temperature thermal penetration of elements.

[0104] In some embodiments of the present application, in step (3), the loading mode of the second coating material includes liquid brushing or solid powder embedding.

[0105] In some embodiments of the present application, in step (3), the solid powder embedding specifically includes embedding the substrate with the first coating in a container containing the second coating material, and the space between the substrate with the first coating and the container is filled with the second coating material to obtain a substrate loaded with the second coating material. The volume filling amount of the second coating material can be 90% to 100% of the total volume of the container. The position of the substrate with the first coating in the container can be at the center of the container or any position below it. The container is an inert container, preferably a high-temperature resistant infiltration box.

[0106] In some embodiments of the present application, in step (3), the high-temperature thermal co-diffusion includes high-temperature heat treatment of the substrate loaded with the second coating material. Preferably, the high-temperature thermal co-diffusion specifically includes using programmed temperature rising to heat the substrate loaded with the second coating material to 850-1200℃, and then maintaining the temperature for a period of time to complete the high-temperature thermal co-diffusion.

[0107] In some embodiments of the present application, the high-temperature thermal co-diffusion in step (3) is carried out in a protective atmosphere, and the protective atmosphere includes nitrogen and / or argon, etc.

[0108] In some embodiments of the present application, in the high-temperature thermal co-diffusion of step (3), the substrate loaded with the second coating material is heated to 850-1100℃, preferably 950-1100℃.

[0109] In some embodiments of the present application, in the high-temperature hot-dip process of step (3), the temperature increasing rate of the programmed temperature increase is 1-10℃ / min.

[0110] In some embodiments of the present application, in the high-temperature hot-dip process of step (3), the time of constant temperature maintenance is 4-9h.

[0111] In some embodiments of the present application, step (3) further comprises polishing after the high-temperature hot-dip process, to obtain the coating of the cracking furnace tube.

[0112] To improve the stability of the catalytically active component in a high-temperature environment and inhibit the migration and agglomeration of the catalytically active component under the action of high temperature, the present application further loads a second coating material on the surface of the first coating, so that the alumina filler in the second coating material fills the gaps between the catalytically active components, and through high-temperature hot-dip, the catalytically active component is fixed and shielded by the inert protective component under the action of high temperature, and the migration and agglomeration phenomenon is effectively controlled. On the other hand, the introduction of the inert protective component also enhances the overall mechanical properties of the coating of the present application, so that the coating has stronger resistance to thermal corrosion and sintering. In the coking inhibition performance evaluation test, the coating of the present application can increase the coking inhibition amount by 34% compared with the inert coating prepared by the traditional method, and can increase the coking inhibition amount by 23% at most compared with the catalytic coating prepared by the traditional method. After repeated coking inhibition evaluation tests, the coking inhibition performance of the coating of the present application decreases less, and after use, the catalytically active component in the coating of the present application can still maintain a high degree of dispersion.

[0113] The third aspect of the present application provides a coating of a cracking furnace tube, which is prepared by the above-mentioned method for preparing a coating of a cracking furnace tube.

[0114] In some embodiments of the present application, the thickness of the coating of the cracking furnace tube is 20-300μm.

[0115] The coating of the cracking furnace tube provided by the present application can be applied in the production of olefins, especially ethylene.

[0116] The existing pyrolysis furnace tube coating technology prepares one or more protective coatings on the inner surface of the pyrolysis furnace tube by using physical or chemical methods. These coatings can not only play a shielding role on the catalytic coking active elements such as iron and nickel in the furnace tube substrate, but also reduce the corrosion of carburization on the pyrolysis furnace tube in the ethylene production process. By further introducing catalytic active elements such as K, Ca or rare earth into the coating, the coating can obtain the catalytic conversion function of radical coking and condensation coking. Although the existing coating technology has good shielding and catalytic conversion effect on catalytic coking, radical coking and condensation coking, the dispersion of the catalytic active elements contained in these coating materials is often low, which makes the inhibition effect of the coating on coke different in different areas during application, causing uneven heating of the coating in some areas, resulting in a decrease in the overall mechanical properties of the coating and the service life of the pyrolysis furnace tube. On the other hand, the catalytic active elements contained in the existing coating technology will migrate and fall off under the action of continuous thermal shock, causing the overall coking inhibition effect of the coating to decrease.

[0117] The ethylene pyrolysis furnace tube coating prepared by the coating material composition of the present application is a ceramic coating. The ceramic coating not only has a high-temperature protection function for the substrate, but also has a catalytic gasification conversion function for the coke generated during the cracking of hydrocarbons. The ceramic coating has excellent mechanical properties, thermal corrosion resistance and sintering resistance. The catalytic active elements contained in the coating have a high dispersion, making the inhibition effect of the coating on coke excellent during application. At the same time, the catalytic active elements contained in the coating are relatively stable, and the migration of the overall elements in the coating is less and the element loss is low during repeated use. Therefore, the ceramic coating can effectively inhibit the coking of the pyrolysis furnace tube and improve the service life of the pyrolysis furnace tube.

[0118] The technical solutions of the present application are specifically illustrated by examples and comparative examples, but the present application is not limited to these examples, and various modifications can be made within the scope of the essential points of the present application.

[0119] The raw materials used in the examples and comparative examples include:

[0120] Acetone: purchased from National Pharmaceutical Reagent, AR (Shanghai test), ≥99.5%;

[0121] Disodium ethylenediaminetetraacetate: purchased from aladdin reagent, 98%;

[0122] Tris (hydroxymethyl) aminomethane: purchased from aladdin reagent, ACS, ≥99.8%;

[0123] Disodium nitrilotriacetic acid: purchased from aladdin reagent, >98.0%;

[0124] Cerium nitrate, potassium nitrate, calcium nitrate, manganese chloride: purchased from National Pharmaceutical Reagent, AR, 99.0%;

[0125] Sodium potassium tartrate: purchased from aladdin reagent, AR, 99.0%;

[0126] Sodium citrate: purchased from aladdin reagent, AR, 99.0%;

[0127] Ammonium acetate: purchased from National Pharmaceutical Reagent, AR (Shanghai test), ≥98.0%;

[0128] Concentrated hydrochloric acid: purchased from National Pharmaceutical Reagent, concentration ≥98%;

[0129] Chromium powder, silicon powder, aluminum powder: purchased from National Pharmaceutical Reagent, particle size 200 mesh;

[0130] Chromium fluoride, sodium fluoride: purchased from National Pharmaceutical Reagent, AR;

[0131] Zirconium chloride, ammonium chloride: purchased from National Pharmaceutical Reagent, AR (Shanghai test), ≥99.0%;

[0132] Alumina: purchased from National Pharmaceutical Reagent, particle size 200 mesh.

[0133] The analysis and test methods used in the examples and comparative examples include:

[0134] 1. The surface morphology and element analysis of the coating material were characterized by Hitachi SU8010 cold field emission scanning electron microscope with an electron microscope scanning voltage of 25kV. In order to better characterize the distribution state of the catalytically active elements in the coating phase, the coating sample was first cut and treated, the coating cross-section thickness was observed by electron microscope, and the EDS single point energy spectrum analysis was carried out from the outer surface of the coating along the vertical direction according to the coating thickness, and the content change graph of the catalytically active elements in the vertical direction of the coating was obtained.

[0135] 2. The coking inhibition performance test of the coating was carried out by using a hanging piece evaluation device. The device suspends the coating sample in a tubular reactor, and then simulates the steam cracking reaction conditions under high temperature conditions by introducing water vapor and hydrocarbon raw material gas into the tubular reactor. Naphtha is used as the cracking raw material gas to test the coking inhibition performance of the coating hanging piece. The reaction conditions are as follows: the mass ratio of naphtha to deionized water is 2:1, the naphtha flow rate is 8mL / min, the deionized water flow rate is 3mL / min, the mixture is preheated to 360℃ after mixing, and then introduced into the tubular reactor for cracking reaction, the cracking reaction temperature is kept at 840℃, the reaction pressure is 30kPa, and the cracking reaction time is 5h. After the reaction, the coating hanging piece is taken out, and the total weight of the coked coating hanging piece W 总重量 is weighed by an electronic balance, and the coating hanging piece weight W0 before the evaluation test is deducted by formula (1) to obtain the coking amount W of the coating hanging piece.焦炭 .

[0136] W 焦炭 = W 总重量 -W0 (1)

[0137] In order to better represent the catalytic conversion effect of the coating on the coke, the coking inhibition rate is used to describe the coking inhibition performance of the coating, and the calculation formula of the coking inhibition rate is shown as formula (2):

[0138] S = (W 参比 -W 焦炭 ) / W 参比 x 100% (2)

[0139] Wherein, S is the coking inhibition rate, W 焦炭 is the coking amount of the coating hanging piece, and W 参比 is the coking amount of the reference hanging piece (i.e. the coking amount of the hanging piece without coating).

[0140] 3, The coating stability test uses a hanging piece evaluation device. The test is carried out by multiple cycles, and the cycle number is 6 times; the single evaluation time is 12h; the reaction conditions are: the mass ratio of naphtha to deionized water is 2.5:1, the naphtha flow is 11mL / min, the deionized water flow is 3mL / min, and after mixing, the mixture is preheated to 360℃ and then introduced into the tubular reactor for pyrolysis reaction, the pyrolysis reaction temperature is kept at 850℃, and the reaction pressure is 30kPa. After the reaction, the coating hanging piece is taken out, weighed and the coking inhibition rate Sn of the coating is calculated (n represents the test cycle number, wherein n=1, 2, 3, 4, 5, 6). After calculation, the coking coating hanging piece is placed in a muffle furnace and calcined in an air atmosphere, the calcination temperature is 900℃, the calcination time is 6h, and after the furnace temperature drops to room temperature, the coating sample piece after removing the coke is taken out and weighed again. After recording, the coating sample piece is hung into the evaluation device again, and the next evaluation cycle test is carried out under the same reaction conditions.

[0141] The composition of the raw material naphtha used in the above coating coking inhibition performance test and coating stability performance test is shown in Table 1.

[0142] Table 1

[0143] Carbon number n-alkanes / % isoalkanes / % olefins / % cycloalkanes / % aromatics / % total / % 3 0.4 0 0 0 0 0.4 4 3.15 0.77 0 0 0 3.92 5 6.55 4.17 0.01 0.64 0 11.37 6 7.15 6.78 0 4.78 0.77 19.48 7 6.66 5.64 0 7.16 1.48 20.94 8 4.62 6.61 0 5.47 2.64 19.34 9 3.16 4.63 0 3.95 1.7 13.44 10 2.02 3.86 0 1.19 0.61 7.68 11 0.51 2.43 0 0.18 0.02 3.14 12 0.23 0.06 0 0 0 0.29 total 34.45 34.95 0.01 23.37 7.22 100

[0144] Preparation of blank sample piece (i.e. sample piece without coating)

[0145] Take Cr 25 Ni 35The alloy as the base material is first processed into several blank samples with a size of 30 mm x 15 mm x 5 mm, the sample pieces are polished with sandpaper to remove the oxide layer on the surface of the sample pieces, then the surface of the sample pieces is cleaned by acetone, and then ultrasonic cleaning is performed, and then the sample pieces are placed in a vacuum drying oven for drying. After drying is completed, the blank sample pieces are obtained and denoted as KB-1.

[0146] Preparation of the first coating material A

[0147] The first coating material A consists of 29% cerium nitrate, 6% disodium ethylenediaminetetraacetate, 10% tris-hydroxymethyl aminomethane and 55% deionized water, based on the total mass of the first coating material A being 100%.

[0148] The preparation method of the first coating material A includes the following steps:

[0149] (a) mixing cerium nitrate, tris-hydroxymethyl aminomethane and a part of deionized water, and stirring at a constant temperature of 30°C and a stirring speed of 400 rpm to form a mixed system;

[0150] (b) mixing disodium nitrilotriacetate and another part of deionized water to obtain a disodium nitrilotriacetate solution with a concentration of 0.5 mol / L;

[0151] (c) adding the disodium nitrilotriacetate solution obtained in step (b) to the mixed system obtained in step (a) at a dropping speed of 3 mL / min, continuously stirring the system at a constant temperature of 40°C and a stirring speed of 300 rpm during the dropping process, and continuing to stir for 60 min after the dropping is completed to obtain the first coating material A.

[0152] The pH value of the first coating material A is 8.

[0153] Preparation of the first coating material B

[0154] The first coating material B consists of 19% lanthanum nitrate, 5% disodium nitrilotriacetate, 7% sodium citrate and 69% deionized water, based on the total mass of the first coating material B being 100%.

[0155] The preparation method of the first coating material B includes the following steps:

[0156] (a) mixing lanthanum nitrate, sodium citrate and a part of deionized water, and stirring at a constant temperature of 40°C and a stirring speed of 400 rpm to form a mixed system;

[0157] (b) mixing disodium nitrilotriacetate and another part of deionized water to obtain a disodium nitrilotriacetate solution with a concentration of 0.4 mol / L;

[0158] (c) the nitrilotriacetic acid disodium solution obtained in step (b) is added dropwise into the mixed system obtained in step (a) at a dropwise adding speed of 2.5 mL / min, and in the process of dropwise adding, the system is continuously stirred at a constant temperature of 40 °C and a stirring speed of 300 rpm, and after the dropwise adding is completed, the stirring is continuously carried out for 60 min, to obtain the first coating material B.

[0159] The pH value of the first coating material B is 8.

[0160] Preparation of the first coating material C

[0161] The first coating material C consists of 17% of cerium nitrate, 6% of potassium nitrate, 5% of nitrilotriacetic acid disodium, 7% of tris-hydroxymethyl aminomethane and 65% of deionized water, based on the total mass of the first coating material C being 100%.

[0162] The preparation method of the first coating material C comprises the following steps:

[0163] (a) cerium nitrate, potassium nitrate, tris-hydroxymethyl aminomethane and a part of deionized water are mixed to form a mixed system under the condition of constant temperature of 40 °C and stirring speed of 300 rpm;

[0164] (b) nitrilotriacetic acid disodium and another part of deionized water are mixed to obtain a nitrilotriacetic acid disodium solution with a concentration of 0.4 mol / L;

[0165] (c) the nitrilotriacetic acid disodium solution obtained in step (b) is added dropwise into the mixed system obtained in step (a) at a dropwise adding speed of 1.5 mL / min, and in the process of dropwise adding, the system is continuously stirred at a constant temperature of 40 °C and a stirring speed of 300 rpm, and after the dropwise adding is completed, the stirring is continuously carried out for 75 min, to obtain the first coating material C.

[0166] The pH value of the first coating material C is 7.

[0167] Preparation of the first coating material D

[0168] The first coating material D consists of 10% of cerium nitrate, 2% of manganese chloride, 10% of potassium sodium tartrate, 15% of ammonium acetate and 63% of deionized water, based on the total mass of the first coating material D being 100%.

[0169] The preparation method of the first coating material D comprises the following steps:

[0170] (a) cerium nitrate, manganese chloride, ammonium acetate and a part of deionized water are mixed to form a mixed system under the condition of constant temperature of 20 °C and stirring speed of 300 rpm;

[0171] (b) mixing potassium sodium tartrate and another part of deionized water to obtain a potassium sodium tartrate solution with a concentration of 1 mol / L;

[0172] (c) adding the potassium sodium tartrate solution obtained in step (b) into the mixed system obtained in step (a) at a dropping speed of 1.5 mL / min, and continuously stirring the system at a constant temperature of 40°C and a stirring speed of 300 rpm during the dropping process; after the dropping is completed, the stirring is continued for 75 min to obtain the first coating material D.

[0173] The pH value of the first coating material D is 8.

[0174] Preparation of the first coating material E

[0175] The first coating material E, with a total mass of 100%, is composed of 10% cerium nitrate, 5% calcium nitrate, 5% nitrilotriacetic acid disodium, 10% sodium citrate and 70% deionized water.

[0176] The preparation method of the first coating material E includes the following steps:

[0177] (a) mixing cerium nitrate, calcium nitrate, sodium citrate and a part of deionized water to form a mixed system under the condition of constant temperature of 40°C and stirring speed of 300 rpm;

[0178] (b) mixing nitrilotriacetic acid disodium and another part of deionized water to obtain a nitrilotriacetic acid disodium solution with a concentration of 0.4 mol / L;

[0179] (c) adding the nitrilotriacetic acid disodium solution obtained in step (b) into the mixed system obtained in step (a) at a dropping speed of 3 mL / min, and continuously stirring the system at a constant temperature of 40°C and a stirring speed of 300 rpm during the dropping process; after the dropping is completed, the stirring is continued for 75 min to obtain the first coating material E.

[0180] The pH value of the first coating material E is 7.

[0181] Example 1

[0182] The KB-1 sample was taken and subjected to acid pickling pretreatment, and a 300 mL dilute hydrochloric acid solution with a concentration of 0.1 mol / L was placed in a glass beaker, and the KB-1 sample was immersed in the dilute hydrochloric acid solution, and after 30 min, the sample was taken out, washed with water to remove the residual dilute hydrochloric acid solution on the surface, and then placed in a vacuum drying oven, set the drying temperature to 60°C, and set the vacuum degree to 400 Pa, dried for 3 h, and then the sample was taken out to obtain the pretreated sample.

[0183] The first coating material A was applied to the surface of the pretreated sample using an atomized spraying method. The sample was then subjected to atmosphere stabilization treatment using a mixture of nitrogen and hydrogen, with a hydrogen volume concentration of 20%. The specific conditions for atmosphere stabilization were: a flow rate of 50 mL / min, a heating rate of 5 °C / min to 650 °C, and a holding temperature of 650 °C for 3 hours to complete the atmosphere stabilization treatment, forming the first coating A1. The sample was then weighed, and the loading of the first coating A1 was found to be 0.149 g.

[0184] The second coating material in this embodiment is a solid particle mixture. Based on the total mass of the solid particle mixture (100%), it consists of the following components: 25% chromium powder, 15% silicon powder, 1.3% chromium fluoride, 1.1% zirconium chloride, 1.5% ammonium chloride, and the balance alumina. The preparation method of this second coating material is as follows: the weighed components are placed in a mixer, mixed for 10 hours, and then the solid particle mixture is poured out to obtain the second coating material.

[0185] The second coating material is loaded onto the surface of a sample with a first coating A1 using a solid powder embedding method. The specific steps are as follows: the sample with the first coating A1 is embedded in an inert container containing the second coating material, the embedded sample is located at the center of the inert container, the volume of the second coating material is 100% of the volume of the inert container, the sample and the second coating material are compacted, and the inert container is sealed.

[0186] The sealed inert container was placed in a muffle furnace for high-temperature heat treatment with nitrogen as the protective atmosphere. The temperature inside the muffle furnace was raised from room temperature to 700°C at a rate of 10°C / min, and then raised from 700°C to 1050°C at a rate of 5°C / min. The temperature was maintained at this rate for 7 hours to complete the high-temperature thermal co-infiltration.

[0187] After cooling, the second coating material powder is removed, and the sample is polished to obtain a sample with a ceramic coating, denoted as SS-1.

[0188] Example 2

[0189] The first coating material B was loaded onto the surface of the pretreated sample provided in Example 1 using an atomized spraying method. The sample loaded with the first coating material B was then treated under the same atmosphere stabilization conditions as in Example 1 to form the first coating B1. After weighing, the loading amount of the first coating B1 was found to be 0.121g.

[0190] In this embodiment, the same second coating material and loading method as in Example 1 are used. After being treated under the same high-temperature thermal co-infiltration conditions as in Example 1, the sample is polished to obtain a sample with a ceramic coating, denoted as SS-2.

[0191] Example 3

[0192] The first coating material C was loaded on the surface of the pretreated sample provided in Example 1 by atomization spraying, and the sample loaded with the first coating material C was treated under the same atmosphere stabilization treatment conditions as in Example 1 to form a first coating C1. After weighing, it was found that the loading amount of the first coating C1 was 0.136 g.

[0193] In this example, the same second coating material and loading method as in Example 1 were used, and after treatment under the same high-temperature hot-dip conditions as in Example 1, the sample was polished to obtain a sample with a ceramic coating, which was denoted as SS-3.

[0194] Example 4

[0195] The first coating material D was loaded on the surface of the pretreated sample provided in Example 1 by atomization spraying, and the sample loaded with the first coating material D was treated under the same atmosphere stabilization treatment conditions as in Example 1 to form a first coating D1. After weighing, it was found that the loading amount of the first coating D1 was 0.117 g.

[0196] In this example, the same second coating material and loading method as in Example 1 were used, and after treatment under the same high-temperature hot-dip conditions as in Example 1, the sample was polished to obtain a sample with a ceramic coating, which was denoted as SS-4.

[0197] Example 5

[0198] The first coating material E was loaded on the surface of the pretreated sample provided in Example 1 by liquid phase brushing, and the sample loaded with the first coating material E was treated under the same atmosphere stabilization treatment conditions as in Example 1 to form a first coating E1. After weighing, it was found that the loading amount of the first coating E1 was 0.127 g.

[0199] In this example, the same second coating material and loading method as in Example 1 were used, and after treatment under the same high-temperature hot-dip conditions as in Example 1, the sample was polished to obtain a sample with a ceramic coating, which was denoted as SS-5.

[0200] Example 6

[0201] Take the KB-1 sample and perform acid pickling pretreatment, using a dilute hydrochloric acid solution with a concentration of 0.05 mol / L, take 300 mL of the dilute hydrochloric acid solution and place it in a glass beaker, immerse the KB-1 sample in the dilute hydrochloric acid solution, immerse the sample for 45 minutes, then take out the sample, wash the sample with water to remove the residual dilute hydrochloric acid solution on the surface, then place the sample in a vacuum drying oven, set the drying temperature to 70°C, set the vacuum degree to 400 Pa, dry for 2 hours, then take out the sample, and obtain the pretreated sample.

[0202] Load the first coating material A on the surface of the pretreated sample by atomization spraying, use a mixture of nitrogen and hydrogen gas to perform atmosphere stabilization treatment on the sample loaded with the first coating material A, the volume concentration of hydrogen in the mixed gas is 30%, the specific conditions of the atmosphere stabilization treatment are: set the flow rate of the mixed gas to 50 mL / min, heat to 650°C at a heating rate of 5°C / min, maintain the temperature at 650°C for 5 hours, complete the atmosphere stabilization treatment, and form the first coating A2. Weigh the sample and obtain the loading amount of the first coating A2, which is 0.141 g.

[0203] The second coating material of this embodiment uses a solid particle mixture, which consists of the following components: chromium powder 25%, silicon powder 15%, sodium fluoride 2.1%, ammonium chloride 1.7%, and the balance of aluminum oxide, based on 100% of the total mass of the solid particle mixture. The preparation method of the second coating material is: weigh the above-mentioned components and put them into a mixer, mix for 10 hours, then pour out the solid particle mixture to obtain the second coating material.

[0204] Load the second coating material on the surface of the sample with the first coating A2 by solid powder embedding method, the specific steps are: embed the sample with the first coating A2 in an inert container containing the second coating material, the embedded sample is located at the center position of the inert container, the volume filling amount of the second coating material is 100% of the inert container, compact the sample and the second coating material, and seal the inert container.

[0205] Place the sealed inert container in a muffle furnace for high temperature heat treatment, use argon as the protective atmosphere, use programmed heating, heat the temperature in the muffle furnace from room temperature to 600°C at a heating rate of 10°C / min, then heat from 600°C to 950°C at a heating rate of 5°C / min, maintain the temperature for 5 hours, complete the high temperature heat permeation.

[0206] After cooling, remove the second coating material powder, polish the sample, and obtain the sample with ceramic coating, denoted as SS-6.

[0207] Example 7

[0208] The first coating material B was loaded on the surface of the pretreated sample provided in Example 6 by atomization spraying, and the sample loaded with the first coating material B was treated under the same atmosphere stabilization treatment conditions as in Example 6 to form a first coating B2. After weighing, it was found that the loading amount of the first coating B2 was 0.157 g.

[0209] In this example, the same second coating material and loading method as in Example 6 were used, and after treatment under the same high-temperature hot-dip conditions as in Example 6, the sample was polished to obtain a sample with a ceramic coating, which was denoted as SS-7.

[0210] Example 8

[0211] The first coating material C was loaded on the surface of the pretreated sample provided in Example 6 by atomization spraying, and the sample loaded with the first coating material C was treated under the same atmosphere stabilization treatment conditions as in Example 6 to form a first coating C2. After weighing, it was found that the loading amount of the first coating C2 was 0.144 g.

[0212] In this example, the same second coating material and loading method as in Example 6 were used, and after treatment under the same high-temperature hot-dip conditions as in Example 6, the sample was polished to obtain a sample with a ceramic coating, which was denoted as SS-8.

[0213] Example 9

[0214] The first coating material D was loaded on the surface of the pretreated sample provided in Example 6 by liquid phase brushing, and the sample loaded with the first coating material D was treated under the same atmosphere stabilization treatment conditions as in Example 6 to form a first coating D2. After weighing, it was found that the loading amount of the first coating D2 was 0.126 g.

[0215] In this example, the same second coating material and loading method as in Example 6 were used, and after treatment under the same high-temperature hot-dip conditions as in Example 6, the sample was polished to obtain a sample with a ceramic coating, which was denoted as SS-9.

[0216] Example 10

[0217] The first coating material E was loaded on the surface of the pretreated sample provided in Example 6 by atomization spraying, and the sample loaded with the first coating material E was treated under the same atmosphere stabilization treatment conditions as in Example 6 to form a first coating E2. After weighing, it was found that the loading amount of the first coating E2 was 0.153 g.

[0218] The second coating material and its loading method of this example are the same as those of Example 6. After being treated under the same high-temperature thermo-diffusion condition as that of Example 6, the sample is polished to obtain a sample with a ceramic coating, which is denoted as SS-10.

[0219] Example 11

[0220] The KB-1 sample is taken and pretreated by acid pickling. A 300 mL dilute hydrochloric acid solution with a concentration of 0.01 mol / L is placed in a glass beaker, and the KB-1 sample is immersed in the dilute hydrochloric acid solution. After 100 minutes, the sample is taken out, washed with water to remove the residual dilute hydrochloric acid solution on the surface, and then placed in a vacuum drying oven. The drying temperature is set to 50°C, and the vacuum degree is set to 400 Pa. After 5 hours of drying, the sample is taken out to obtain the pretreated sample.

[0221] The first coating material A is loaded on the surface of the pretreated sample by atomization spraying. The sample loaded with the first coating material A is subjected to atmosphere stabilization treatment using a mixture of nitrogen and hydrogen gas. The volume concentration of hydrogen in the mixture is 10%. The specific conditions of the atmosphere stabilization treatment are as follows: the flow rate of the mixture is set to 70 mL / min, the temperature is raised to 650°C at a rate of 5°C / min, and the temperature is maintained at 650°C for 6 hours. After the atmosphere stabilization treatment is completed, the first coating A3 is formed. The sample is taken out and weighed to obtain the loading amount of the first coating A3, which is 0.122 g.

[0222] The second coating material of this example is a solid particle mixture. Based on the total mass of the solid particle mixture being 100%, it is composed of the following components: chromium powder 25%, silicon powder 15%, aluminum powder 10%, sodium fluoride 1.3%, ammonium chloride 1.7%, and the balance of aluminum oxide. The preparation method of the second coating material is as follows: the weighed components are loaded into a mixer, mixed for 10 hours, and then the solid particle mixture is poured out to obtain the second coating material.

[0223] The second coating material is loaded on the surface of the sample with the first coating A3 by solid powder embedding method. The specific steps are as follows: the sample with the first coating A3 is embedded in an inert container containing the second coating material, the embedded sample is located at the center of the inert container, the volume filling amount of the second coating material is 100% of the inert container, and the inert container is sealed.

[0224] The sealed inert container is placed in a muffle furnace for high-temperature heat treatment. Nitrogen is used as the protective atmosphere, and the temperature in the muffle furnace is raised at a rate of 10°C / min from room temperature to 700°C, and then at a rate of 5°C / min from 700°C to 1100°C. The temperature is maintained at 1100°C for 5 hours to complete the high-temperature thermo-diffusion.

[0225] After cooling, the second coating material powder was removed, and the sample was polished to obtain a sample with a ceramic coating, denoted as SS-11.

[0226] Example 12

[0227] The first coating material B was loaded on the surface of the pretreated sample provided in Example 11 by atomization spraying, and the sample loaded with the first coating material B was treated under the same atmosphere stabilization treatment conditions as in Example 11 to form a first coating B3. After weighing, it was found that the loading amount of the first coating B3 was 0.111 g.

[0228] In this example, the same second coating material and loading method as in Example 11 were used, and after treatment under the same high-temperature hot-dip conditions as in Example 11, the sample was polished to obtain a sample with a ceramic coating, denoted as SS-12.

[0229] Example 13

[0230] The first coating material C was loaded on the surface of the pretreated sample provided in Example 11 by liquid phase brushing, and the sample loaded with the first coating material C was treated under the same atmosphere stabilization treatment conditions as in Example 11 to form a first coating C3. After weighing, it was found that the loading amount of the first coating C3 was 0.133 g.

[0231] In this example, the same second coating material and loading method as in Example 11 were used, and after treatment under the same high-temperature hot-dip conditions as in Example 11, the sample was polished to obtain a sample with a ceramic coating, denoted as SS-13.

[0232] Example 14

[0233] The first coating material D was loaded on the surface of the pretreated sample provided in Example 11 by atomization spraying, and the sample loaded with the first coating material D was treated under the same atmosphere stabilization treatment conditions as in Example 11 to form a first coating D3. After weighing, it was found that the loading amount of the first coating D3 was 0.130 g.

[0234] In this example, the same second coating material and loading method as in Example 11 were used, and after treatment under the same high-temperature hot-dip conditions as in Example 11, the sample was polished to obtain a sample with a ceramic coating, denoted as SS-14.

[0235] Example 15

[0236] The first coating material E was loaded on the surface of the pretreated sample provided in Example 11 by atomization spraying, and the sample loaded with the first coating material E was treated under the same atmosphere stabilization treatment conditions as in Example 11 to form a first coating E3. After weighing, the loading amount of the first coating E3 was found to be 0.109 g.

[0237] The same second coating material and loading method as in Example 11 were used in this example, and the sample was polished after being treated under the same high-temperature thermal diffusion conditions as in Example 11 to obtain a sample with a ceramic coating, which was denoted as SS-15.

[0238] Example 16

[0239] The sample KB-1 was pretreated by pickling in this example, and the loading of the first coating material A and the atmosphere stabilization treatment conditions were the same as in Example 1. The loading amount of the first coating A5 on the surface of the sample obtained after the above steps was 0.146 g.

[0240] The second coating material used in this example was a liquid slurry, which was composed of the following components: chromium powder 35%, silicon powder 17%, chromium fluoride 1.4%, zirconium chloride 1.1%, ammonium chloride 1.5%, aluminum oxide 24%, and ethanol 20%, based on the total mass of the liquid slurry being 100%. The preparation method of the second coating material was as follows: the weighed components were added to a beaker, stirred and mixed for 40 min, and then the liquid slurry was poured out to obtain the second coating material.

[0241] The second coating material was loaded on the surface of the sample with the first coating A5 by liquid brushing, and the sample coated with the second coating material was placed in a 60°C drying oven for 1 h. Then the sample was taken out and placed in a muffle furnace for high-temperature heat treatment. Nitrogen was used as the protective atmosphere, and the temperature in the muffle furnace was raised at a rate of 10°C / min from room temperature to 700°C, and then at a rate of 5°C / min from 700°C to 1050°C. The temperature was maintained at 1050°C for 7 h to complete the high-temperature thermal diffusion.

[0242] After cooling, the sample was polished to obtain a sample with a ceramic coating, which was denoted as SS-16.

[0243] Comparative Example 1

[0244] An inert coating material was used in this comparative example, which was composed of the following components: chromium powder 21%, silicon powder 4%, chromium fluoride 0.4%, zirconium chloride 0.7%, ammonium chloride 3.2%, and aluminum oxide 70.7%, based on the total mass of the inert coating material being 100%. The preparation method of the inert coating material was as follows: the weighed components were loaded into a mixer, mixed for 10 h, and then the solid particulate mixture was poured out to obtain the inert coating material.

[0245] The inert coating material is loaded on the surface of the KB-1 sample by a solid powder embedding method. The specific steps are as follows: embedding the KB-1 sample in an inert container containing inert coating material, embedding the sample at the center of the inert container, the volume filling amount of the inert coating material is 100% of the inert container, compacting the sample and the inert coating material, and sealing the inert container.

[0246] The sealed inert container is placed in a muffle furnace for high-temperature heat treatment, nitrogen is used as the protective atmosphere, the temperature in the muffle furnace is raised at a rate of 10℃ / min from room temperature to 700℃, then raised at a rate of 5℃ / min from 700℃ to 950℃, and maintained at a constant temperature for 7h. After cooling, the inert coating material powder is removed, the sample is polished, and the sample with inert coating is obtained, denoted as DB-1.

[0247] Comparative Example 2

[0248] Take the KB-1 sample, and prepare a coating on the sample according to the technical solution disclosed in CN114540749A. The specific preparation steps are as follows:

[0249] Take the KB-1 sample, and embed it in an inert container containing barrier coating penetrant, compact the sample and the barrier coating penetrant material, and seal the inert container. Among them, the barrier coating penetrant consists of the following components: chromium powder 21%, silicon powder 4%, chromium fluoride 0.4%, zirconium oxide 0.7%, ammonium chloride 3.2%, and aluminum oxide 70.7%, based on the total mass of the barrier coating penetrant being 100%. The sealed inert container is placed in a muffle furnace for chemical heat treatment, the temperature in the muffle furnace is raised at a rate of 10℃ / min from room temperature to 700℃, then raised at a rate of 5℃ / min from 700℃ to 950℃, and maintained at a constant temperature for 7h. After cooling, the penetrant powder is removed, the sample is polished, and the sample with barrier coating is obtained.

[0250] The sample with the barrier coating layer was embedded in an inert container containing the decoking coating layer penetrant, the sample was compacted with the decoking coating layer penetrant, and the inert container was sealed. The decoking coating layer penetrant consisted of the following components: chromium powder 16.5%, silicon powder 4%, chromium fluoride 0.2%, lanthanum oxide 4.5%, ammonium chloride 3.2%, and aluminum oxide 71.6%, based on the total mass of the decoking coating layer penetrant being 100%. The sealed inert container was placed in a muffle furnace for chemical heat treatment, the temperature in the muffle furnace was raised at a rate of 5°C / min from room temperature to 700°C, and then raised at a rate of 5°C / min from 700°C to 850°C, and maintained at 850°C for 7 h. After cooling, the penetrant powder was removed, the sample was polished, and then washed twice with a saturated calcium hydroxide solution for 5 min each time. After drying, the sample was stabilized by calcination in air at 600°C for 5 h to obtain a sample with a self-decoking coating layer, which was denoted as DB-2.

[0251] Comparative Example 3

[0252] Preparation of the first coating material F: the first coating material F consisted of the following components: 30% cerium nitrate and 70% anhydrous ethanol, based on the total mass of the first coating material F being 100%. The first coating material F was prepared by mixing cerium nitrate and anhydrous ethanol, and then continuously stirring at a stirring speed of 400 rpm and a constant temperature of 40°C for 60 min.

[0253] The first coating material F was applied to the surface of the KB-1 sample by liquid brushing, and the sample with the first coating material F was subjected to atmosphere stabilization treatment using a mixed gas of nitrogen and hydrogen, the volume concentration of hydrogen in the mixed gas being 20%, the specific conditions of the atmosphere stabilization treatment being as follows: the set flow rate of the mixed gas was 50 mL / min, the temperature was raised to 650°C at a rate of 5°C / min, and the temperature was maintained at 650°C for 3 h to complete the atmosphere stabilization treatment, thereby forming the first coating F1. The sample was removed and weighed, and the loading amount of the first coating F1 was 0.157 g.

[0254] The second coating material of this example was a solid particle mixture, which consisted of the following components: chromium powder 25%, silicon powder 15%, chromium fluoride 1.3%, zirconium chloride 1.1%, ammonium chloride 1.5%, and the balance being aluminum oxide, based on the total mass of the solid particle mixture being 100%. The preparation method of the second coating material was as follows: the weighed components were loaded into a mixer, mixed for 10 h, and then the solid particle mixture was poured out to obtain the second coating material.

[0255] The second coating material is loaded on the surface of the sample sheet with the first coating F1 by a solid powder embedding method. The specific steps are as follows: embedding the sample sheet with the first coating F1 in an inert container containing the second coating material, embedding the sample sheet at the center position of the inert container, the volume filling amount of the second coating material is 100% of the inert container, compacting the sample sheet and the second coating material, and sealing the inert container.

[0256] The sealed inert container is placed in a muffle furnace for high-temperature heat treatment, nitrogen is used as the protective atmosphere, the temperature in the muffle furnace is raised at a rate of 10℃ / min from room temperature to 700℃, then raised at a rate of 5℃ / min from 700℃ to 950℃, and maintained at 950℃ for 7h to complete the high-temperature heat permeation.

[0257] After cooling, the second coating material powder is removed, and the sample sheet is polished to obtain a sample sheet with a ceramic coating, denoted as DB-3.

[0258] Comparative Example 4

[0259] The KB-1 sample sheet is pretreated under the same acid pretreatment conditions as in Example 1.

[0260] Preparation of the first coating material G: the first coating material G is composed of 45% cerium nitrate and 55% deionized water, based on the total mass of the first coating material G being 100%; the first coating material G is prepared by mixing cerium nitrate and deionized water, and continuously stirring at a stirring speed of 400rpm and a constant temperature of 40℃ for 60min to obtain the first coating material G.

[0261] The first coating material G is loaded on the surface of the pretreated sample sheet by atomization spraying, and the sample sheet loaded with the first coating material G is subjected to atmosphere stabilization treatment using a mixture of nitrogen and hydrogen, the volume concentration of hydrogen in the mixture is 20%, the specific conditions of the atmosphere stabilization treatment are as follows: the set flow of the mixture is 50mL / min, the temperature is raised to 650℃ at a rate of 5℃ / min, and maintained at 650℃ for 3h to complete the atmosphere stabilization treatment and form the first coating G1. The sample sheet is taken out and weighed, and the loading amount of the first coating G1 is 0.181g.

[0262] The second coating material of this example is a solid particle mixture, which is composed of 25% chromium powder, 15% silicon powder, 1.3% chromium fluoride, 1.1% zirconium chloride, 1.5% ammonium chloride, and the balance of aluminum oxide, based on the total mass of the solid particle mixture being 100%. The preparation method of the second coating material is as follows: weighing the above components and loading them into a mixer, mixing for 10h, then pouring out the solid particle mixture to obtain the second coating material.

[0263] The second coating material is loaded on the surface of the sample sheet with the first coating G1 by using a solid powder embedding method, and the specific steps are as follows: embedding the sample sheet with the first coating G1 in an inert container containing the second coating material, embedding the sample sheet in the center position of the inert container, the volume filling amount of the second coating material is 100% of the inert container, compacting the sample sheet and the second coating material, and sealing the inert container.

[0264] The sealed inert container is placed in a muffle furnace for high-temperature heat treatment, nitrogen is used as a protective atmosphere, the temperature in the muffle furnace is raised at a temperature raising rate of 10℃ / min from room temperature to 700℃, and then raised at a temperature raising rate of 5℃ / min from 700℃ to 1050℃, and the temperature is kept constant for 7h, and the high-temperature heat permeation is completed.

[0265] After cooling, the second coating material powder is removed, the sample sheet is polished, and the sample sheet with the ceramic coating is obtained, which is recorded as DB-4.

[0266] The analysis and test results of the above examples and comparative examples are as follows.

[0267] 1, Coating material surface morphology and element analysis characterization

[0268] From the SEM photos and EDS element characterization analysis results of the coatings of Figure 1 , Figure 2 , Figure 3 , Figure 4 , it can be seen that the catalytically active components in the ceramic coating prepared by the application are uniformly dispersed on the surface of the ceramic coating, and the dispersion degree of the catalytically active components is high. The ceramic coating is cut, and the element distribution of the coating cross section is analyzed, and from the analysis results, it can be seen that the catalytically active components not only uniformly distribute on the surface of the coating, but also maintain a high dispersion degree in the body phase of the coating, and the overall distribution of the catalytically active components is relatively uniform.

[0269] 2, Coating coking inhibition performance

[0270] The coking amount and coking inhibition rate of the coatings prepared in Examples 1-16 and Comparative Examples 1-4 under the same coking inhibition performance evaluation conditions are shown in Table 2.

[0271] Table 2

[0272]

[0273]

[0274] As can be seen from the data in Table 2, the ceramic coating prepared by the present application has good catalytic conversion function for coke. Taking the data of SS-1 as an example, the coke deposition amount of the ceramic coating of SS-1 is significantly reduced relative to the coke deposition amount of the blank sample KB-1, and the coke inhibition rate of SS-1 can reach 90.06% at the highest. Relative to the inert coating of DB-1, the coke inhibition rate of SS-1 is significantly improved. Relative to the existing catalytic coating of DB-2, the coke inhibition rate of SS-1 can be improved by 23% at the highest. According to the scanning electron microscope characterization results, it can be seen that the catalytically active components in the ceramic coating prepared by the present application can maintain a high dispersity, the catalytically active components can fully exert their catalytic effect, the overall catalytic conversion efficiency of the ceramic coating for coke is high, and finally the ceramic coating has more excellent coke inhibition performance.

[0275] 3. Stability of the coating

[0276] Through repeated use of the coating and evaluation of the coke inhibition performance, the coke inhibition rate of the coating prepared by Example 1, Example 6, Example 11 and Comparative Example 2 is plotted against the change trend of the use cycle, as shown in Figure 5 As can be seen from Figure 5 , the coke inhibition performance of the ceramic coating prepared by the present application remains basically unchanged after repeated use. This shows that the catalytically active components in the ceramic coating of the present application have high stability under high temperature environment, the element migration and agglomeration under high temperature effect is weak, the inert protective components can fill the gaps between the catalytically active components through high-temperature thermal diffusion, so that the catalytically active components are fixed and blocked by the inert protective components under high temperature effect, and the migration and agglomeration phenomenon is effectively controlled.

[0277] Obviously, the above examples of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description, and it is impossible to enumerate all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present application still fall within the protection scope of the present application.

Claims

1. A coating material composition for a pyrolysis furnace tube, comprising: First coating material and second coating material; The first coating material, by weight (100%), comprises the following components: 10-40% catalytically active component, 2-30% complexing agent, 5-20% buffer, and 40-70% first dispersant. The catalytically active component comprises one or more compounds of alkali metals, alkaline earth metals, rare earth metals, and transition metals. The complexing agent comprises one or more of disodium nitritetriacetate, disodium ethylenediaminetetraacetate, dithizone, 8-hydroxyquinoline, o-phenanthroline, potassium sodium tartrate, and polyphosphates. The second coating material is a liquid slurry or a mixture of solid particles; based on the total mass of the liquid slurry (100%), it comprises the following components: 10-65% inert protective component, 0.1-3.0% flux, 1.0-5.0% activator, 20-80% filler, and the balance being a second dispersant; based on the total mass of the solid particle mixture (100%), it comprises the following components: 15-60% inert protective component, 0.1-2.5% flux, 1.0-6.0% activator, and the balance being a filler.

2. The coating material composition according to claim 1, wherein, Taking the total mass of the first coating material as 100%, its It comprises the following components: 10-29% catalytically active component, 5-15% complexing agent, 5-15% buffer, and 40-70% first dispersant.

3. The coating material composition according to claim 1, wherein, In the composition of the first coating material, the alkali metal element includes one or more combinations of Li, Na and K; the alkaline earth metal element includes one or more combinations of Mg, Ca, Sr and Ba; the rare earth metal element includes one or more combinations of La, Ce, Pr, Nd and Y; and the transition metal element includes one or more combinations of Co, Mn, Mo, Cu, Zn, V, Ti, Cr, W, Rh and Hf.

4. The coating material composition according to claim 1, wherein, In the composition of the first coating material, the buffer includes one or a combination of several of ammonium acetate, tris(hydroxymethyl)aminomethane, and citrate.

5. The coating material composition according to claim 1, wherein, In the composition of the first coating material, the first dispersant includes one or a combination of several of deionized water, ethanol, ethylene glycol, acetone and chloroform.

6. The coating material composition according to claim 1, wherein, The first coating material is prepared by at least the following steps: (a) mixing a catalytically active component, a buffer and a portion of a first dispersant, and stirring to form a mixed system; (b) mixing a complexing agent and another portion of the first dispersant to obtain a complexing agent solution; (c) under stirring conditions, adding the complexing agent solution obtained in step (b) dropwise to the mixed system obtained in step (a), and continuing to stir for a period of time after the dropwise addition is completed to obtain the first coating material.

7. The coating material composition according to claim 1, wherein, The liquid slurry comprises, by weight, 100% of the total mass, the following components: 15-60% inert protective component, 0.1-2.5% flux, 1.0-2.0% activator, 24-70% filler, and the balance of second dispersant.

8. The coating material composition according to claim 1, wherein, The solid particle mixture comprises the following components, based on a total mass of 100%: The composition includes 24-58% inert protective components, 0.1-2.5% flux, 1.1-4.0% activator, and the balance being filler.

9. The coating material composition according to claim 1, wherein, In the composition of the second coating material, the inert protective component includes one or a combination of several of elemental chromium, elemental silicon, and elemental aluminum.

10. The coating material composition according to claim 1, wherein, In the composition of the second coating material, the flux includes one or a combination of several of chromium fluoride, sodium fluoride, zirconium chloride, and potassium fluoride.

11. The coating material composition according to claim 1, wherein, In the composition of the second coating material, the activator includes one or a combination of several of ammonium chloride, ammonium fluoride and ammonium sulfate.

12. The coating material composition according to claim 1, wherein, In the composition of the second coating material, the filler includes aluminum oxide.

13. The coating material composition according to claim 1, wherein, In the composition of the second coating material, the second dispersant includes one or a combination of several of deionized water, ethanol, ethylene glycol, acetone and chloroform.

14. A method for preparing a coating for a pyrolysis furnace tube, the method comprising forming a coating using the pyrolysis furnace tube coating material composition according to any one of claims 1-13, the method comprising the following steps: (1) Pre-treat the surface of the substrate; (2) Load the first coating material onto the surface of the pretreated substrate, and then perform atmosphere stabilization treatment to form the first coating; (3) Load the second coating material onto the surface of the first coating and then perform high-temperature thermal co-infiltration to obtain the pyrolysis furnace tube coating.

15. The preparation method according to claim 14, wherein, In step (1), the method of pretreating the substrate surface includes immersing the substrate in an inorganic acid solution.

16. The preparation method according to claim 14, wherein, In step (2), the loading method of the first coating material includes one or a combination of liquid phase brushing, atomized spraying, physical vapor deposition, chemical vapor deposition and immersion.

17. The preparation method according to claim 14, wherein, In step (2), the loading of the first coating on the pretreated substrate surface is 74–370 g / m². 2 .

18. The preparation method according to claim 14, wherein, In step (2), the atmosphere stabilization treatment includes: using a mixture of nitrogen and hydrogen as the stabilization atmosphere, and using programmed heating to heat the substrate loaded with the first coating material to the stabilization temperature. After reaching the stabilization temperature, the temperature is maintained at a constant temperature for a period of time to complete the atmosphere stabilization treatment.

19. The preparation method according to claim 18, wherein, In the atmosphere stabilization process of step (2), the stabilization temperature is 500-750°C.

20. The preparation method according to claim 18, wherein, In the atmosphere stabilization process in step (2), the constant temperature is maintained for 3 to 7 hours.

21. The preparation method according to claim 14, wherein, In step (3), the loading method of the second coating material includes liquid phase brushing or solid powder embedding.

22. The preparation method according to claim 14, wherein, In step (3), the high-temperature thermal co-percolation includes: performing high-temperature heat treatment on the substrate loaded with the second coating material.

23. The preparation method according to claim 22, wherein, In the high-temperature thermal co-infiltration in step (3), the temperature of the high-temperature heat treatment is 850-1200℃, and the constant temperature is maintained for 4-9 hours.

24. The preparation method according to claim 22, wherein, In step (3), the high-temperature thermal co-percolation is carried out in a protective atmosphere, which includes nitrogen and / or argon.

25. A pyrolysis furnace tube coating, which is prepared by the method for preparing the pyrolysis furnace tube coating according to any one of claims 14-24.

26. The coating for the pyrolysis furnace tube according to claim 25, wherein, The thickness of the coating on the pyrolysis furnace tube is 20–300 μm.

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