Heat-resistant stainless steel pipe and processing technology thereof

Abstract

The application relates to a heat-resistant stainless steel pipe, the chemical composition of which comprises C, Si, Mn, P, S, Cr, Ni, Mo, Nd, Ce, iron and impurities; the surface of the stainless steel pipe is coated with a heat-resistant coating which comprises the following components: thermosetting phenolic resin, 4-chloro phthalic acid, agarose, branched polyethylene imine, a catalyst, a curing agent, 4-N,N-dimethylpyridine and dimethylformamide; and relates to a processing technology of the heat-resistant stainless steel pipe. The thermosetting phenolic resin has good heat resistance, the agarose makes the heat-resistant coating form a compact protective layer, the esterification product of 4-chloro phthalic acid and agarose has a benzene ring rigid group, 4-N,N-dimethylpyridine activates the carboxyl group of 4-chloro phthalic acid, the polymerization product obtained by the reaction of 4-chloro phthalic acid and branched polyethylene imine, and the synergistic effect of the components each containing a rigid group, effectively improve the heat resistance of the coating.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of stainless steel pipes, in particular to a heat-resistant stainless steel pipe and a processing technology thereof. BACKGROUND

[0002] Heat-resistant steel is a kind of alloy steel with high strength and good chemical stability at high temperature; a stainless steel pipe is a steel pipe made of stainless steel.

[0003] At present, austenitic stainless steel is commonly used, that is, stainless steel with austenitic structure at room temperature, when the steel contains Cr about 18%, Ni 8%-10%, and C about 0.1%, the austenitic structure is stable.

[0004] According to the related technology, the inventors believe that the heat resistance of the original heat-resistant steel cannot meet the development needs of the market, and therefore the heat resistance of the stainless steel pipe still needs to be improved. SUMMARY

[0005] In order to improve the heat resistance of the original stainless steel pipe, the application provides a heat-resistant stainless steel pipe and a processing technology thereof.

[0006] In a first aspect, the application provides a heat-resistant stainless steel pipe adopting the following technical scheme:

[0007] A heat-resistant stainless steel pipe, in terms of weight percentage, has the following chemical composition: C: 0.35-0.45%; Si: 1.5-2.0%; Mn: 1.0-2.5%; P: 0.02-0.04%; S: 0.03-0.04%; Cr: 26-30%; Ni: 20-25%; Mo: 0.3-0.4%; Nd: 0.005-0.008%; Ce: 0.006-0.008%; the balance is iron and impurities; a heat-resistant coating is coated on the surface of the stainless steel pipe, and the heat-resistant coating comprises the following components in terms of weight percentage:

[0008] 50-60 parts of thermosetting phenolic resin;

[0009] 8-10 parts of 4-chloro-phthalic acid;

[0010] 4-5 parts of agarose;

[0011] 5-6 parts of branched polyethyleneimine;

[0012] 1-2 parts of a catalyst;

[0013] 1-2 parts of a curing agent;

[0014] 3-4 parts of 4-N,N-dimethylpyridine;

[0015] 15-20 parts of dimethylformamide.

[0016] By adopting the technical scheme, the thermosetting phenolic resin has good heat resistance and can be cured by heating; the agarose is in a dissolved state above 90℃, and forms a good semi-solid state gel when the temperature drops to 35-40℃; the agarose sugar chains are intertwined with each other in a double helix mode to form a double helix structure by hydrogen bond, so that the heat-resistant coating forms a tightly covered protective layer on the surface of the stainless steel pipe; the carboxyl groups of the 4-chlorophthalic acid react with the hydroxyl groups in the agarose to form esterification products, so that the agarose is modified and a benzene ring rigid group is introduced; meanwhile, the carboxyl groups of the 4-chlorophthalic acid are activated by 4-N,N-dimethylpyridine, so that the remaining 4-chlorophthalic acid can react with the branched polyethyleneimine, and the obtained polymerization product also has an aromatic ring rigid structure, thereby the heat-resistant coating has improved heat resistance and forms a good heat insulation protection through the synergistic effect of the components containing rigid groups.

[0017] Preferably, the heat-resistant coating further comprises 6-8 parts of 2-methyl-2-butenoic acid, 2-3 parts of 4-(ethoxylhydroxyl) phenylboronic acid pinacol ester and 1-2 parts of p-toluene sulfonic acid.

[0018] By adopting the technical scheme, under the catalysis of the p-toluene sulfonic acid, the 2-methyl-2-butenoic acid is added to the thermosetting phenolic resin, the esterification reaction occurs between the hydroxymethyl active groups of the phenolic resin and the carboxyl groups, and then the 4-(ethoxylhydroxyl) phenylboronic acid pinacol ester carrying an ester group is further added to further occur the ester exchange reaction, so that the B-O bond and the rigid benzene ring with increased bond energy and rigid structure are introduced into the product, and the heat resistance of the heat-resistant coating is improved.

[0019] Preferably, the heat-resistant coating further comprises 1-2 parts of graphene oxide and 3-4 parts of isopropyl phenyl diphenyl phosphate.

[0020] By adopting the technical scheme, the isopropyl phenyl diphenyl phosphate with phosphoric acid groups can be well dispersed with the carboxyl groups carried on the graphene oxide, and the sheet layer composite with more phase structures is formed by using the sheet layer structure of the graphene oxide, so as to improve the thermal decomposition temperature of the heat-resistant coating and the barrier property of the heat-resistant coating, thereby improving the heat resistance of the treated stainless steel pipe.

[0021] Preferably, the heat-resistant coating further comprises 1-2 parts of dodecanol.

[0022] By adopting the technical scheme, a large number of phenolic hydroxyl groups, carboxyl groups and epoxy groups exist on the surface or edge of the graphene oxide, the oxygen-containing groups make the graphene oxide interlayer spacing larger, and after the graphene oxide swells, the monofunctional small molecule dodecanol with a hydroxyl group is inserted between the graphene oxide layers, the compatibility with the graphene oxide is higher, and meanwhile, the sheet layer density is further increased, and the barrier density of the heat-resistant coating is improved.

[0023] Preferably, the catalyst comprises 1-2 parts of p-toluenesulfonic acid catalyst and 1-2 parts of dicyclohexyl carbodiimide; and the curing agent is curing agent NL.

[0024] By adopting the technical scheme, p-toluenesulfonic acid is used to catalyze the esterification reaction of 4-chlorophthalic acid and agarose, and dicyclohexyl carbodiimide is used to catalyze the condensation reaction of the amide compound generated by the branched polyethylene imine after the carboxyl group of 4-chlorophthalic acid is activated by 4-N,N-dimethylpyridine.

[0025] In a second aspect, the application provides a processing process of a heat-resistant stainless steel pipe, which adopts the following technical scheme:

[0026] The processing process of the heat-resistant stainless steel pipe comprises the following steps:

[0027] S1. Prepare a heat-resistant coating raw material; blend 4-chlorophthalic acid, agarose, 5-6 parts of dimethylformamide and 1-2 parts of a catalyst, stir and react at 90-95 DEG C for 50-60 min, continue to add 4-N,N-dimethylpyridine, stir for 15-18 min, then add branched polyethylene imine and the remaining 1-2 parts of catalyst, and continue to stir for 1-1.5 h; finally, add thermosetting phenolic resin, the remaining dimethylformamide and a curing agent, blend and stir at 50-60 DEG C for 60-70 min;

[0028] S2. Surface coating of the heat-resistant coating; preheat the stainless steel pipe to 100-150 DEG C, spray the heat-resistant coating material prepared in S1 on the stainless steel pipe by using a spray gun, the spraying distance is 20-25 mm, the spraying pressure is 0.8-1.2 MPa, and after the spraying is completed, dry at 150-200 DEG C for 8-10 min.

[0029] Preferably, S1 further comprises the following steps:

[0030] Blend 8-10 parts of 4-chlorophthalic acid, 4-5 parts of agarose, 5-6 parts of dimethylformamide and 1-2 parts of p-toluenesulfonic acid catalyst, stir and react at 90-95 DEG C for 50-60 min, continue to add 3-4 parts of 4-N,N-dimethylpyridine, stir for 15-18 min, then add 5-6 parts of branched polyethylene imine and 1-2 parts of dicyclohexyl carbodiimide, and continue to stir for 1-1.5 h to obtain a mixture A;

[0031] Mix 50-60 parts of thermosetting phenolic resin and the rest of dimethylformamide, then add 6-8 parts of 2-methyl-2-butenoic acid and 0.4-0.6 parts of p-toluenesulfonic acid, stir at 50-60℃ for 50-60min; then add 2-3 parts of 4-(ethoxylhydroxyl) phenylboronic acid pinacol ester and the rest of p-toluenesulfonic acid, continue to stir for 1-1.5h, to obtain mixture B;

[0032] Stir 1-2 parts of dodecanol and 8-10 parts of distilled water to form a dodecanol solution; then add 1-2 parts of graphene oxide to 15-20 parts of distilled water, soak for 24h for full swelling; then add the dodecanol solution dropwise to the swollen graphene oxide solution under stirring at 70-80℃, continue to stir for 40-50min, then add 3-4 parts of isopropyl phenyl phosphate, ultrasonic at 200-300W power for 15-20min, to obtain mixture C;

[0033] Mix mixture A, mixture B and mixture C at 50-60℃ and stir for 60-70min.

[0034] In summary, the present application has the following beneficial technical effects:

[0035] 1. The thermosetting phenolic resin has good heat resistance, and can be cured by heating; the agarose is in a dissolved state above 90℃, and forms a good semi-solid state gel when the temperature drops to 35-40℃, and the agarose sugar chains are intertwined with each other in a double helix manner by hydrogen bonding to form a double helix structure, which is closely arranged, so that the heat-resistant coating can form a closely covered protective layer on the surface of the stainless steel pipe; the carboxyl group of 4-chlorophthalic acid reacts with the hydroxyl group in the agarose to form an esterification product, which modifies the agarose and introduces a benzene ring rigid group; at the same time, the 4-N,N-dimethylpyridine activates the carboxyl group of 4-chlorophthalic acid, so that the remaining 4-chlorophthalic acid can react with branched polyethyleneimine, and the obtained polymerization product also has an aromatic ring rigid structure, thereby the synergistic effect of the components containing rigid groups reduces the movement of molecular chain segments, reduces the free volume, increases the bulk density of the heat-resistant coating after curing, effectively improves the heat resistance of the coating, and forms a good heat insulation protection;

[0036] 2. Under the catalysis of p-toluenesulfonic acid, 2-methyl-2-butenoic acid is added to the thermosetting phenolic resin, and the hydroxymethyl active group of the phenolic resin reacts with the carboxyl group to form an esterification reaction, and then 4-(ethoxylhydroxyl) phenylboronic acid pinacol ester carrying an ester group is further added to further form an ester exchange reaction, thereby introducing B-O bond and rigid benzene ring to increase the bond energy and rigid structure, and modifying the heat resistance of the heat-resistant coating;

[0037] 3. The isopropyl phenyl phosphate with phosphoric acid group can be compatible with the carboxyl carried on the graphene oxide to form a good dispersion, and the sheet structure of the graphene oxide is used to form a sheet composite with more phase structure, which can improve the thermal decomposition temperature of the heat-resistant coating on the one hand and improve the barrier property of the heat-resistant coating on the other hand, thereby improving the heat resistance of the treated stainless steel pipe;

[0038] 4. There are a large number of phenolic hydroxyl groups, carboxyl groups and epoxy groups on the surface or edge of the graphene oxide, and these oxygen-containing groups make the interlayer spacing of the graphene oxide larger, so that the graphene oxide swells, and the monofunctional small molecule dodecanol with hydroxyl groups is inserted between the layers of the graphene oxide, which has higher compatibility with the graphene oxide, and further increases the sheet density and improves the barrier density of the heat-resistant coating. DETAILED DESCRIPTION

[0039] The present application is further described below.

[0040] In the present application, the thermosetting phenolic resin is provided by Jinan Dahui Chemical Technology Co., Ltd., model 2123, item number 001; the agarose is provided by Hubei Bojie Biological Technology Co., Ltd., CAS: 9012-36-6; the branched polyethyleneimine is purchased from Biyun Tian Biological Technology Co., Ltd., product number C0539-25ml; 4-(ethoxyhydroxy) phenylboronic acid pinacol ester is provided by Shanghai Yuan Ye Biological Technology Co., Ltd., item number: S96086-1g; the graphene oxide is provided by Suzhou Carbon-Fullerene Technology Co., Ltd., model TF-12041, sheet diameter 10-50 μm, specific surface area 100-300 m 2 / g.

[0041] The raw materials used in the following embodiments can be obtained from ordinary market sales unless otherwise specified.

[0042] EMBODIMENT

[0043] EMBODIMENT 1

[0044] The present embodiment discloses a heat-resistant stainless steel pipe and its processing technology; a heat-resistant stainless steel pipe, the chemical composition of which is expressed in percentage by weight: C: 0.35%; Si: 1.5%; Mn: 1.0%; P: 0.02%; S: 0.03%; Cr: 26%; Ni: 20%; Mo: 0.3%; Nd: 0.005%; Ce: 0.006%; the balance is iron and impurities; the surface of the stainless steel pipe is coated with a heat-resistant coating, and the heat-resistant coating comprises the following components: thermosetting phenolic resin, 4-chloro phthalic acid, agarose, branched polyethyleneimine, catalyst, curing agent, 4-N,N-dimethylpyridine and dimethylformamide, wherein the catalyst comprises p-methylbenzenesulfonic acid catalyst and dicyclohexyl carbodiimide, and the curing agent is curing agent NL, and the content of each component is shown in Table 1.

[0045] A processing technology of heat-resistant stainless steel pipe, comprising the following steps:

[0046] S1. Prepare heat-resistant coating raw materials; blend 4-chloro phthalic acid, agarose, 5 parts of dimethylformamide and 1 part of p-toluenesulfonic acid catalyst, stir and react at 90°C for 50 min, continue to add 4-N,N-dimethylpyridine, stir for 15 min, then add branched polyethyleneimine and 1 part of dicyclohexyl carbodiimide, heat to 60°C and continue to stir for 1 h; finally add thermosetting phenolic resin, the remaining dimethylformamide and curing agent, blend and stir at 50°C for 60 min;

[0047] S2. Surface coating of heat-resistant coating; preheat the stainless steel pipe to 100°C, use a spray gun to spray the heat-resistant coating prepared in S1 on the stainless steel pipe, the spraying distance is 20 mm, the spraying pressure is 0.8 Mpa, and after spraying, dry at 150°C for 8 min.

[0048] Example 2

[0049] The embodiment discloses a heat-resistant stainless steel pipe and a processing technology thereof; a heat-resistant stainless steel pipe, the chemical composition of which is expressed by weight percentage: C: 0.45%; Si: 2.0%; Mn: 2.5%; P: 0.04%; S: 0.04%; Cr: 30%; Ni: 25%; Mo: 0.4%; Nd: 0.008%; Ce: 0.008%; the balance is iron and impurities; the surface of the stainless steel pipe is coated with a heat-resistant coating, and the heat-resistant coating comprises the following components: thermosetting phenolic resin, 4-chloro phthalic acid, agarose, branched polyethyleneimine, a catalyst, a curing agent, 4-N,N-dimethylpyridine and dimethylformamide, wherein the catalyst comprises p-toluenesulfonic acid catalyst and dicyclohexyl carbodiimide, the curing agent is curing agent NL, and the content of each component is shown in Table 1.

[0050] A processing technology of heat-resistant stainless steel pipe, comprising the following steps:

[0051] S1. Prepare heat-resistant coating raw materials; blend 4-chloro phthalic acid, agarose, 5 parts of dimethylformamide and 1 part of p-toluenesulfonic acid catalyst, stir and react at 90°C for 50 min, continue to add 4-N,N-dimethylpyridine, stir for 15 min, then add branched polyethyleneimine and 1 part of dicyclohexyl carbodiimide, heat to 60°C and continue to stir for 1 h; finally add thermosetting phenolic resin, the remaining dimethylformamide and curing agent, blend and stir at 50°C for 60 min;

[0052] S2. Surface coating of heat-resistant coating; preheat the stainless steel pipe to 100°C, use a spray gun to spray the heat-resistant coating prepared in S1 on the stainless steel pipe, the spraying distance is 20 mm, the spraying pressure is 0.8 Mpa, and after spraying, dry at 150°C for 8 min.

[0053] Example 3

[0054] The present embodiment discloses a heat-resistant stainless steel pipe and a processing technology thereof. The heat-resistant stainless steel pipe comprises the following components in percentage by weight: C: 0.40%; Si: 1.8%; Mn: 2.0%; P: 0.03%; S: 0.03%; Cr: 28%; Ni: 24%; Mo: 0.4%; Nd: 0.006%; Ce: 0.007%; and the balance of iron and impurities. The surface of the stainless steel pipe is coated with a heat-resistant coating layer, which comprises the following components: thermosetting phenolic resin, 4-chloro-phthalic acid, agarose, branched polyethyleneimine, catalyst, curing agent, 4-N,N-dimethylpyridine and dimethylformamide. The catalyst comprises p-toluenesulfonic acid catalyst and dicyclohexyl carbodiimide, and the curing agent is curing agent NL. The content of each component is shown in Table 1.

[0055] The processing technology of the heat-resistant stainless steel pipe comprises the following steps:

[0056] S1. Prepare heat-resistant coating raw materials. Blend 4-chloro-phthalic acid, agarose, 5 parts of dimethylformamide and 1.5 parts of p-toluenesulfonic acid catalyst, stir and react at 93℃ for 55 min, then add 4-N,N-dimethylpyridine and stir for 17 min, and then add branched polyethyleneimine and 1.5 parts of dicyclohexyl carbodiimide, and continue to stir at 65℃ for 1.2 h. Finally, add thermosetting phenolic resin, the remaining dimethylformamide and the curing agent, and blend and stir at 55℃ for 65 min.

[0057] S2. Surface coating of heat-resistant coating. Preheat the stainless steel pipe to 130℃, and use a spray gun to spray the heat-resistant coating prepared in S1 on the stainless steel pipe, with a spraying distance of 24 mm and a spraying pressure of 1.0 Mpa. After spraying, dry at 180℃ for 9 min.

[0058] Example 4

[0059] The present embodiment discloses a heat-resistant stainless steel pipe and a processing technology thereof. The heat-resistant stainless steel pipe is different from that of Example 1 in that the heat-resistant coating layer coated on the surface of the stainless steel pipe comprises the following components:

[0060] The heat-resistant coating layer comprises the following components: thermosetting phenolic resin, 4-chloro-phthalic acid, agarose, branched polyethyleneimine, catalyst, curing agent, 4-N,N-dimethylpyridine, dimethylformamide, 2-methyl-2-butenoic acid, 4-(ethoxyhydroxy) phenyl boronic acid pinacol ester, p-toluenesulfonic acid, graphene oxide, isopropyl phenyl phosphate diphenyl ester and dodecanol. The catalyst comprises p-toluenesulfonic acid catalyst and dicyclohexyl carbodiimide, and the curing agent is curing agent NL. The content of each component is shown in Table 1.

[0061] A processing process of a heat-resistant stainless steel pipe, which is different from example 1 in that S1 comprises the following steps:

[0062] 4-chloro-phthalic acid, agarose, 5 parts of dimethylformamide and 1 part of p-toluenesulfonic acid catalyst were blended and stirred at 90°C for 50 min, 4-N,N-dimethylpyridine was continuously added, stirred for 15 min, then branched polyethyleneimine and 1 part of dicyclohexyl carbodiimide were added, and stirred for 1 h to obtain mixture A;

[0063] The thermosetting phenolic resin and the remaining dimethylformamide were mixed, 2-methyl-2-butenoic acid and 0.4 parts of p-toluenesulfonic acid were added, and stirred at 50°C for 50 min; 4-(ethoxylhydroxyl) phenylboronic acid pinacol ester and the remaining p-toluenesulfonic acid were added, and stirred for 1 h to obtain mixture B;

[0064] Dodecanol and 8 parts of distilled water were thoroughly stirred to form a dodecanol solution; graphene oxide was added to 15 parts of distilled water and soaked for 24 h for sufficient swelling; then the dodecanol solution was added dropwise to the swollen graphene oxide solution under stirring at 70°C, and stirred for 40 min; cumene diphenyl phosphate was added, and ultrasonic was performed at a power of 200W for 15 min to obtain mixture C;

[0065] Mixture A, mixture B and mixture C were blended and stirred at 50°C for 60 min.

[0066] Example 5

[0067] The present embodiment discloses a heat-resistant stainless steel pipe and a processing process thereof; a heat-resistant stainless steel pipe, which is different from example 2 in that the heat-resistant coating coated on the surface of the stainless steel pipe comprises the following components:

[0068] The thermosetting phenolic resin, 4-chloro-phthalic acid, agarose, branched polyethyleneimine, catalyst, curing agent, 4-N,N-dimethylpyridine, dimethylformamide, 2-methyl-2-butenoic acid, 4-(ethoxylhydroxyl) phenylboronic acid pinacol ester, p-toluenesulfonic acid, graphene oxide, cumene diphenyl phosphate and dodecanol, wherein the catalyst comprises p-toluenesulfonic acid catalyst and dicyclohexyl carbodiimide, and the curing agent is curing agent NL, and the content of each component is shown in Table 1.

[0069] A processing process of a heat-resistant stainless steel pipe, which is different from example 2 in that S1 comprises the following steps:

[0070] Mixing 4-chloro-phthalic acid, agarose, 6 parts of dimethylformamide and 2 parts of p-toluenesulfonic acid catalyst, stirring at 95℃ for 60 min, continue to add 4-N,N-dimethylpyridine, stirring for 18 min, then add branched polyethyleneimine and 2 parts of dicyclohexyl carbodiimide, continue to stir for 1.5h, get mixture A;

[0071] Mixing thermosetting phenolic resin and the rest of dimethylformamide, then add 2-methyl-2-butenoic acid and 0.6 parts of p-toluenesulfonic acid, stirring at 60℃ for 60 min; then add 4-(ethoxyhydroxy) phenylboronic acid pinacol ester and the rest of p-toluenesulfonic acid, continue to stir for 1.5h, get mixture B;

[0072] Mixing dodecanol and 10 parts of distilled water into dodecanol solution; then add graphene oxide into 20 parts of distilled water, soak for 24h for full swelling; then add dodecanol solution into the swelling graphene oxide solution drop by drop under stirring at 80℃, continue to stir for 50 min, then add cumene phosphate, ultrasonic for 20 min at 300W power, get mixture C;

[0073] Mixing mixture A, mixture B and mixture C at 60℃ and stirring for 70 min.

[0074] Example 6

[0075] The embodiment discloses a kind of heat-resistant stainless steel pipe and its processing technology;A kind of heat-resistant stainless steel pipe, the difference from example 3 is that the heat-resistant coating coated on the surface of stainless steel pipe includes the following components:

[0076] Thermosetting phenolic resin, 4-chloro-phthalic acid, agarose, branched polyethyleneimine, catalyst, curing agent, 4-N,N-dimethylpyridine, dimethylformamide, 2-methyl-2-butenoic acid, 4-(ethoxyhydroxy) phenylboronic acid pinacol ester, p-toluenesulfonic acid, graphene oxide, cumene phosphate and dodecanol, wherein the catalyst includes p-toluenesulfonic acid catalyst and dicyclohexyl carbodiimide, and the curing agent is curing agent NL, and the content of each component is shown in Table 1.

[0077] A kind of processing technology of heat-resistant stainless steel pipe, the difference from example 3 is that S1 includes the following steps:

[0078] Mixing 4-chloro-phthalic acid, agarose, 6 parts of dimethylformamide and 2 parts of p-toluenesulfonic acid catalyst, stirring at 95℃ for 60 min, continue to add 4-N,N-dimethylpyridine, stirring for 18 min, then add branched polyethyleneimine and 2 parts of dicyclohexyl carbodiimide, continue to stir for 1.5h, get mixture A;

[0079] The thermosetting phenolic resin and the rest of dimethylformamide were mixed, 2-methyl-2-butenoic acid and 0.5 parts of p-toluenesulfonic acid were added, and stirred at 55°C for 55 min; 4-(ethoxyhydroxy) phenylboronic acid pinacol ester and the rest of p-toluenesulfonic acid were added, and continued to stir for 1.2 h, to obtain mixture B;

[0080] The dodecanol and 9 parts of distilled water were fully stirred into a dodecanol solution; the graphene oxide was added into 18 parts of distilled water, and soaked for 24 h for full swelling; then the dodecanol solution was added dropwise into the swollen graphene oxide solution under stirring at 75°C, and continued to stir for 45 min; the cumene phosphate diphenyl ester was added, and ultrasonic was performed at 250W power for 18 min, to obtain mixture C;

[0081] The mixture A, the mixture B and the mixture C were blended and stirred at 55°C for 65 min.

[0082] Example 7

[0083] The difference from Example 4 is that the 2-methyl-2-butenoic acid is replaced by acetic acid, and the content of each component is shown in Table 2.

[0084] Example 8

[0085] The difference from Example 7 is that the 4-(ethoxyhydroxy) phenylboronic acid pinacol ester is replaced by ethanol, and the content of each component is shown in Table 2.

[0086] Example 9

[0087] The difference from Example 4 is that the graphene oxide is replaced by montmorillonite, and the content of each component is shown in Table 2.

[0088] Example 10

[0089] The difference from Example 9 is that the cumene phosphate diphenyl ester is replaced by acetic acid, and the content of each component is shown in Table 2.

[0090] Example 11

[0091] The difference from Example 10 is that the dodecanol is replaced by dodecylamine, and the content of each component is shown in Table 2.

[0092] Comparative Example

[0093] Comparative Example 1

[0094] The difference from Example 1 is that the Cr24Ni7N steel is used as Comparative Example 1.

[0095] Comparative Example 2

[0096] The difference from Example 1 is that the heat-resistant coating layer comprises 50 parts of thermosetting phenolic resin and 1 part of curing agent.

[0097] Comparative Example 3

[0098] The difference from Example 1 is that 4-chlorophthalic acid is replaced by phenylacetic acid.

[0099] Comparative Example 4

[0100] The difference from Comparative Example 3 is that agarose is replaced by pectin.

[0101] Comparative Example 5

[0102] The difference from Comparative Example 3 is that branched polyethyleneimine is replaced by triethylamine.

[0103] Comparative Example 6

[0104] The difference from Example 1 is that 4-N,N-dimethylpyridine is not added.

[0105] Table 1 Component content table of Examples 1-6

[0106]

[0107] Table 2 Component content table of Examples 7-11

[0108]

[0109] Performance test

[0110] Test method: φ12mm×66mm samples were prepared according to the processing technology of each example and comparative example; the samples of Example 1, Example 4 and Comparative Example 1 were tested for fracture time at 25℃ and 1000℃ under the same stress of 30MPa, and the longer the fracture time at high temperature, the better the heat resistance; the test results are shown in Table 3 below.

[0111] The samples of each example and comparative example were tested for fracture time at 1000℃ under the same stress of 30MPa, and the test results are shown in Table 4 below.

[0112] Table 3 Performance test results of Example 1, 4 and Comparative Example 1

[0113] 25°C break time / h 1000°C break time / h Example 1 70 63 Example 4 78 70 Comparative Example 1 45 39

[0114] Table 4 Performance test results of each example and comparative example

[0115] 1000°C break time / h Example 1 63 Example 2 66 Example 3 64 Example 4 70 Example 5 74 Example 6 72 Example 7 69 Example 8 66 Example 9 67 Example 10 65 Example 11 63 Comparative Example 1 39 Comparative Example 2 47 Comparative Example 3 59 Comparative Example 4 57 Comparative Example 5 55 Comparative Example 6 60

[0116] The specific embodiments are only illustrative of the application and are not intended to limit the scope of the application. Any modifications without creative contribution made by those skilled in the art after reading the specification can be made to the embodiments within the scope of the claims of the application and are protected by the patent law.

Claims

1. A heat-resistant stainless steel pipe, characterized in that: The chemical composition, expressed as a percentage by weight, is as follows: C: 0.35-0.45%; Si: 1.5-2.0%; Mn: 1.0-2.5%; P: 0.02-0.04%; S: 0.03-0.04%; Cr: 26-30%; Ni: 20-25%; Mo: 0.3-0.4%; Nd: 0.005-0.008%; Ce: 0.006-0.008%; the balance being iron and impurities. The stainless steel pipe surface is coated with a heat-resistant coating, which comprises the following components in parts by weight: 50-60 parts thermosetting phenolic resin; 8-10 parts of 4-chlorophthalic acid; 4-5 parts agarose; 5-6 parts branched polyethyleneimine; 2-4 parts catalyst; 1-2 parts hardener; 3-4 parts of 4-N,N-dimethylpyridine; 15-20 parts dimethylformamide; The catalyst comprises 1-2 parts of p-toluenesulfonic acid catalyst and 1-2 parts of dicyclohexylcarbodiimide; the curing agent is curing agent NL.

2. The heat-resistant stainless steel pipe according to claim 1, characterized in that: By weight, the heat-resistant coating further comprises 6-8 parts of 2-methyl-2-butenoic acid, 2-3 parts of 4-(ethoxyhydroxy)phenylboronic acid pinacol ester and 1-2 parts of p-toluenesulfonic acid.

3. The heat-resistant stainless steel pipe according to claim 2, characterized in that: By weight, the heat-resistant coating also includes 1-2 parts graphene oxide and 3-4 parts cumene diphenyl phosphate.

4. The heat-resistant stainless steel pipe according to claim 3, characterized in that: The heat-resistant coating also includes 1-2 parts dodecanol by weight.

5. The processing technology for a heat-resistant stainless steel pipe according to claim 1, characterized in that, Includes the following steps: S1. Prepare heat-resistant coating raw materials; mix 4-chlorophthalic acid, agarose, 5-6 parts of dimethylformamide and 1-2 parts of catalyst, stir and react at 90-95℃ for 50-60 min, continue to add 4-N,N-dimethylpyridine, stir for 15-18 min, then add branched polyethyleneimine and the remaining 1-2 parts of catalyst, continue stirring for 1-1.5 h; finally add thermosetting phenolic resin, the remaining dimethylformamide and curing agent, mix and stir at 50-60℃ for 60-70 min; S2. Surface coating with heat-resistant coating: Preheat the stainless steel pipe to 100-150℃, and spray the heat-resistant coating material prepared in S1 onto the stainless steel pipe with a spray gun. The spraying distance is 20-25mm, the spraying pressure is 0.8-1.2Mpa, and after spraying, dry at 150-200℃ for 8-10min.

6. The processing technology for a heat-resistant stainless steel pipe according to claim 4, characterized in that: Includes the following steps: S1. Prepare heat-resistant coating raw material: Mix 8-10 parts of 4-chlorophthalic acid, 4-5 parts of agarose, 5-6 parts of dimethylformamide and 1-2 parts of p-toluenesulfonic acid catalyst, stir and react at 90-95℃ for 50-60 min, add 3-4 parts of 4-N,N-dimethylpyridine, stir for 15-18 min, then add 5-6 parts of branched polyethyleneimine and 1-2 parts of dicyclohexylcarbodiimine, continue stirring for 1-1.5 h to obtain mixture A; Mix 50-60 parts of thermosetting phenolic resin and the remaining dimethylformamide, then add 6-8 parts of 2-methyl-2-butenoic acid and 0.4-0.6 parts of p-toluenesulfonic acid and stir at 50-60℃ for 50-60 min; then add 2-3 parts of 4-(ethoxyhydroxy)phenylboronic acid pinacol ester and the remaining p-toluenesulfonic acid, and continue stirring for 1-1.5 h to obtain mixture B; Mix 1-2 parts dodecanol and 8-10 parts distilled water thoroughly to form a dodecanol solution; then add 1-2 parts graphene oxide to 15-20 parts distilled water and soak for 24 hours to fully swell; then add the dodecanol solution dropwise to the swollen graphene oxide solution under stirring at 70-80℃, continue stirring for 40-50 minutes, then add 3-4 parts cumene diphenyl phosphate, and sonicate at 200-300W power for 15-20 minutes to obtain mixture C; Mixtures A, B, and C are blended and stirred at 50-60°C for 60-70 minutes. S2. Surface coating with heat-resistant coating: Preheat the stainless steel pipe to 100-150℃, and spray the heat-resistant coating material prepared in S1 onto the stainless steel pipe with a spray gun. The spraying distance is 20-25mm, the spraying pressure is 0.8-1.2Mpa, and after spraying, dry at 150-200℃ for 8-10min.

Images