Precision stainless steel for corrosion-resistant pneumatic cylinder and processing method thereof

Abstract

The invention relates to the technical field of stainless steel and discloses precision stainless steel for corrosion-resistant pneumatic cylinders and a processing method thereof. The method comprises the following steps: step 1: heating austenitic stainless steel to 1150-1200° C. and holding the temperature for 2-3 hours, forging at 850-950° C., solution treating at 1050-1100° C. for 1-2 hours, water quenching, machining, and nitriding at 520-550° C. for 4-5 hours to obtain precision stainless steel A; step 2: pickling the precision stainless steel A for 7-10 minutes, washing, drying, adding the resulting solution to an electrolyte for micro-arc oxidation for 5-8 minutes, immersing the solution in a modified composite sol sealing agent for 30-40 seconds, removing the solution and performing sealing treatment to obtain the precision stainless steel for corrosion-resistant pneumatic cylinders.

Description

Technical Field

[0001] The invention relates to the technical field of stainless steel, in particular to precision stainless steel for corrosion-resistant pneumatic cylinders and a processing method thereof. Background Art

[0002] In modern industrial production, pneumatic cylinders are an important actuator and are widely used in various fields. However, in some harsh working environments, such as chemical industry and marine engineering, pneumatic cylinders face serious corrosion problems, which not only affects the service life of the pneumatic cylinders, but may also cause equipment failure and affect the normal production.

[0003] At present, the stainless steel materials commonly used in pneumatic cylinders on the market have certain wear resistance, but have certain limitations in corrosion resistance and precision. Ordinary stainless steel is prone to corrosion when facing strong corrosive media, resulting in a decrease in material performance, which affects the application of stainless steel in pneumatic cylinders. Therefore, the preparation of a precision stainless steel material with excellent corrosion resistance is of great practical significance. Summary of the Invention

[0004] The object of the present invention is to provide a corrosion-resistant precision stainless steel for a pneumatic cylinder and a processing method thereof, so as to solve the problems raised in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for processing precision stainless steel for a corrosion-resistant pneumatic cylinder includes the following steps:

[0007] Step 1: Heat the austenitic stainless steel to 1150-1200℃ and keep it for 2-3 hours, forge it at 850-950℃, solution treat it at 1050-1100℃ for 1-2 hours, water quench it, machine it, and nitride it at 520-550℃ for 4-5 hours to obtain precision stainless steel A.

[0008] Step 2: Pickle the precision stainless steel A for 7 to 10 minutes, clean it, dry it, and then add it to the electrolyte for micro-arc oxidation for 5 to 8 minutes. Then immerse it in the modified composite sol sealing agent for 30 to 40 seconds, take it out for sealing, and obtain corrosion-resistant precision stainless steel for pneumatic cylinders.

[0009] More optimally, the raw materials of the electrolyte include the following components: 8~12g / L sodium silicate, 3~6g / L potassium hydroxide, 1.5~3g / L sodium titanate, and 0.7~1.2g / L modified graphene.

[0010] The more optimized preparation method of the modified graphene is as follows: (1) adding KH560 to an ethanol aqueous solution and uniformly mixing, adding graphene and ultrasonically dispersing, adjusting the pH to 4-5, stirring at 50-60°C for 4-5 hours, centrifuging, washing, and drying to obtain epoxidized graphene; (2) adding epoxidized graphene to N,N-dimethylformamide and ultrasonically dispersing, adding dopamine and 4-fluoro-3-trifluoromethylaniline, heating to 50-60°C under a nitrogen atmosphere and stirring for 2-3 hours, removing the solvent, and obtaining modified graphene.

[0011] More optimally, the raw materials of the epoxidized graphene include the following components: 1-1.5 parts of KH560, 15-20 parts of ethanol aqueous solution, and 0.7-1 parts of graphene, measured by mass; the mass ratio of the epoxidized graphene, dopamine, and 4-fluoro-3-trifluoromethylaniline is 1:(0.2-03):(0.4-0.6).

[0012] A more optimized preparation method of the modified composite sol sealing agent is as follows: adding fluorinated-phenylsilane resin to a mixed solution of ethanol and toluene, mixing uniformly to obtain a mixed solution; adding aluminum nitrate to deionized water and mixing uniformly, adding nano zirconium oxide and ultrasonically dispersing to obtain a mixed solution A; uniformly mixing tetraethyl orthosilicate, ethanol, and deionized water, adding hydrochloric acid to adjust the pH to 3-4 and stirring for 1.5-2.5 hours, adding the mixed solution A and mixing uniformly for 1-2 hours, adjusting the pH to 6-7, adding a silane coupling agent-ethanol aqueous solution and mixing uniformly, slowly adding the mixed solution and mixing uniformly for 40-50 minutes, and aging for 3-5 hours to obtain a modified composite sol sealing agent.

[0013] More optimally, the mass ratio of tetraethyl silicate, ethanol, and deionized water is 1:(3-4):(2-2.5); the mass ratio of aluminum nitrate, nano zirconium oxide, and tetraethyl silicate is 1:(0.7-1.2):(2-3);

[0014] The added amount of the silane coupling agent is 1.2-1.8 wt %, including KH560 and tridecafluorooctyltrimethoxysilane in a mass ratio of (0.2-0.3):1; the added amount of the fluorinated-phenylsilane resin is 5-10 wt %; and the volume ratio of the ethanol and toluene is (3-4):2.

[0015] The more optimized preparation method of the fluorinated-phenylsilane resin is as follows: (1) adding oxalic acid to deionized water and mixing uniformly, adding phenyltrimethoxysilane and mixing uniformly, stirring at 50-55°C for 5-6 hours, adding vinyltrimethoxysilane and dibutyltin dilaurate, heating to 90-95°C and reflux for 4-5 hours, and rotary evaporation to obtain vinyl-phenylsilane resin; (2) adding vinyl-phenylsilane resin to tetrahydrofuran and mixing uniformly, adding 1H,1H,2H,2H-perfluorodecanethiol and mixing uniformly, adding initiator, irradiating under ultraviolet light for 1-2 hours, adding to anhydrous ethanol for flocculation purification, and repeating 2-3 times to obtain fluorinated-phenylsilane resin.

[0016] More optimally, the raw materials of the vinyl-phenylsilane resin include the following components: 0.06-0.1 parts of oxalic acid, 15-20 parts of phenyltrimethoxysilane, 6-8 parts of vinyltrimethoxysilane, 0.2-0.3 parts of dibutyltin dilaurate, and 7-8 parts of deionized water, by mass; the mass ratio of the vinyl-phenylsilane resin to 1H,1H,2H,2H-perfluorodecanethiol is 1:(0.2-0.5).

[0017] The optimized process conditions of the sealing treatment are: immersing in the modified composite sol sealing agent, drying at 40-50°C for 1-2 hours, heating to 300-320°C at a rate of 1-2°C / min, keeping warm for 30-40 minutes, and repeating 3-4 times; the process conditions of the micro-arc oxidation are: duty cycle 25-40%, current density 4-6A / dm 2 , operating frequency 300~400Hz.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention uses austenitic stainless steel as a base material; the austenitic stainless steel is heated to 1150-1200°C and kept warm for 2-3 hours, so that the austenitic grains soften, providing a good plastic deformation foundation for subsequent forging and reducing the risk of forging cracking; then forging is performed at 850-950°C, and the pressure during the forging process can close internal microcracks, pores and other defects; solution treatment is performed at 1050-1100°C for 1-2 hours, followed by water quenching and mechanical processing; wherein the solution treatment can inhibit the precipitation of carbides, form a supersaturated solid solution, improve the corrosion resistance of the material, eliminate the work hardening caused by forging, and enable the material to regain good plasticity, which is convenient for subsequent mechanical processing; nitriding is performed at 520-550°C for 4-5 hours, thereby facilitating the improvement of the corrosion resistance of the precision stainless steel.

[0020] In order to improve the corrosion resistance and heat resistance of precision stainless steel, the scheme first performs micro-arc oxidation on it to obtain a micro-arc oxidation layer; then it is taken out from the modified composite glue and sealed to obtain corrosion-resistant precision stainless steel for pneumatic cylinders;

[0021] In this scheme, micro-arc oxidation treatment can improve the density of the surface layer of precision stainless steel A, but residual pores still exist. Therefore, silicon oxide and aluminum oxide are made into a sealing sol for sealing treatment to reduce surface roughness, reduce the friction coefficient and improve wear resistance. To further improve corrosion resistance, nano-zirconia and fluorinated-phenylsilane resin are introduced into the sealing sol. Among them, nano-zirconia has good heat resistance and corrosion resistance, which can effectively improve the performance of stainless steel.

[0022] The fluorinated-phenylsilane resin first attacks the methoxy group in trimethoxysilane through oxalic acid to generate phenyltrihydroxysilane and methanol; the silanol groups between phenyltrihydroxysilane molecules are dehydrated and condensed to form siloxane bonds, generating branched phenylsilane oligomers; vinyltrimethoxysilane is hydrolyzed under acidic conditions to generate vinyltrihydroxysilane, and its silanol groups are co-condensed with the silanol groups of phenylsilane oligomers to form a copolymerized siloxane chain containing phenyl and vinyl groups; under the catalysis of dibutyltin dilaurate and reflux conditions of 90~95℃, the residual silanol groups in the siloxane chain are further condensed to form a three-dimensional network structure, thereby improving corrosion resistance and heat resistance.

[0023] However, adding vinyltrimethoxysilane to the sealing sol made of silicon oxide and aluminum oxide will reduce the penetration effect, thus affecting the sealing performance. To improve the sealing effect, 1H,1H,2H,2H-perfluorodecanethiol is introduced into the vinyl-phenylsilane resin through a thiol-ene click reaction. The tightly arranged perfluorocarbon chains form a barrier with low surface energy and high chemical inertness. This gives the sealing agent a low surface energy, significantly reducing the viscosity of the sealing agent sol, making it easier to penetrate into the pores of the micro-arc oxidation layer, further enhancing the hydrophobicity and corrosion resistance.

[0024] Tridecafluorooctyltrimethoxysilane and KH-560 are added to the sealing sol to adjust the compatibility with the fluorinated-phenylsilane resin; the phase separation problem that may be caused by physical blending is avoided, and the stability of the overall performance of the sealing agent is ensured.

[0025] In order to improve the bonding strength between the micro-arc oxidation layer and the stainless steel substrate and the modified composite adhesive; in the scheme, modified graphene is added to the micro-arc oxidation electrolyte; epoxy groups are introduced on the graphene surface and then under certain conditions, the epoxy groups are combined with the amino groups on 4-fluoro-3-trifluoromethylaniline and dopamine to obtain modified graphene; among them, 4-fluoro-3-trifluoromethylaniline can reduce the surface energy, enhance the interfacial compatibility with the sealing agent, and interact with the hydroxyl groups on the surface of the precision stainless steel substrate through hydrogen bonds, thereby improving the corrosion resistance of the precision stainless steel; the catechol structure of dopamine forms a strong coordination bond with the metal oxide, further enhancing the bonding strength with the sealing agent and precision stainless steel, thereby improving corrosion resistance and heat resistance. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] In the following specific embodiments, parts are by mass. In this embodiment, it should be noted that the purchase manufacturers of all raw materials involved in the present invention are not particularly restricted. Examples include: graphene (graphene nanosheets) with an average particle size of 5 nm; KH560 (3-(2,3-epoxypropyloxy)propyltrimethoxysilane) with a CAS number of 2530-83-8; dopamine with a CAS number of 51-61-6; 4-fluoro-3-trifluoromethylaniline with a CAS number of 2357-47-3; aluminum nitrate with a CAS number of 13473-90- 0; the CAS number of tetraethyl orthosilicate is 562-90-3; the CAS number of vinyltrimethoxysilane is 2768-02-7; the CAS number of phenyltrimethoxysilane is 2996-92-1; the CAS number of 1H,1H,2H,2H-perfluorodecanethiol is 34143-74-3; the product number of nano zirconium oxide is XH-ZrO2-20; the CAS number of tridecafluorooctyltrimethoxysilane is 85857-16-5; the CAS number of 1-hydroxycyclohexylphenyl ketone (initiator) is 947-19-3.

[0028] In the scheme, the preparation method of modified graphene is as follows: (1) adding 1.2 parts of KH560 to 15 parts of ethanol-water solution and mixing uniformly, adding 0.7 parts of graphene and ultrasonically dispersing, adjusting the pH to 4, stirring at 55°C for 5 hours, centrifuging, washing, and drying to obtain epoxidized graphene; (2) weighing epoxidized graphene, dopamine, and 4-fluoro-3-trifluoromethylaniline in a mass ratio of 1:0.2:0.4; adding epoxidized graphene to N,N-dimethylformamide and ultrasonically dispersing, adding dopamine and 4-fluoro-3-trifluoromethylaniline, heating to 55°C under a nitrogen atmosphere and stirring for 3 hours, removing the solvent, and obtaining modified graphene.

[0029] Example 1: A method for processing precision stainless steel for a corrosion-resistant pneumatic cylinder, comprising the following steps:

[0030] Step 1: Austenitic stainless steel (316L austenitic stainless steel) was heated to 1150°C and kept at this temperature for 2 hours, forged at 900°C (forging ratio 3.5), solution treated at 1100°C for 1.5 hours, water quenched, machined, and nitrided at 530°C for 4 hours to obtain precision stainless steel A.

[0031] Step 2: Soak the precision stainless steel in acid A for 7 minutes, wash it, dry it, add it to the electrolyte for micro-arc oxidation for 8 minutes, immerse it in the modified composite sol sealing agent for 30 seconds, take it out, dry it at 50°C for 2 hours, heat it to 300°C at a rate of 2°C / min, keep it warm for 40 minutes, and repeat the sealing three times to obtain corrosion-resistant precision stainless steel for pneumatic cylinders;

[0032] The electrolyte raw materials include the following components: 10g / L sodium silicate, 5g / L potassium hydroxide, 1.5g / L cerium nitrate, and 0.7g / L modified graphene; the process conditions of micro-arc oxidation are: duty cycle 30%, current density 4A / dm 2 , operating frequency 400Hz;

[0033] The modified composite sol sealing agent is prepared by: adding a fluorinated-phenylsilane resin to a mixed solution of ethanol and toluene, uniformly mixing to obtain a mixed solution; adding aluminum nitrate to deionized water, uniformly mixing, adding nano zirconium oxide, and ultrasonically dispersing to obtain a mixed solution A; uniformly mixing tetraethyl orthosilicate, ethanol, and deionized water, adding hydrochloric acid to adjust the pH to 3, stirring for 1.5 hours, adding the mixed solution A, uniformly mixing for 2 hours, adjusting the pH to 6.5, adding a silane coupling agent-ethanol aqueous solution, uniformly mixing, slowly adding the mixed solution, uniformly mixing for 50 minutes, and aging for 4 hours to obtain the modified composite sol sealing agent;

[0034] The mass ratio of tetraethyl silicate, ethanol, and deionized water is 1:4:2; the mass ratio of aluminum nitrate, nano zirconium oxide, and tetraethyl silicate is 1:0.7:3; the amount of silane coupling agent added is 1.2wt%, including KH560 and tridecafluorooctyltrimethoxysilane in a mass ratio of 0.2:1; the volume ratio of ethanol and toluene is 3:2; the amount of fluorinated-phenylsilane resin added is 5wt%;

[0035] The preparation method of fluorinated phenylsilane resin is as follows: (1) adding 0.1 parts of oxalic acid to 8 parts of deionized water and mixing them uniformly, adding 15 parts of phenyltrimethoxysilane and mixing them uniformly, stirring at 55°C for 5 hours, adding 6 parts of vinyltrimethoxysilane and 0.25 parts of dibutyltin dilaurate, heating to 90°C and reflux for 4 hours, removing the solvent, and obtaining vinyl-phenylsilane resin; (2) weighing vinyl-phenylsilane resin and 1H,1H,2H,2H-perfluorodecanethiol in a mass ratio of 1:0.2; adding vinyl-phenylsilane resin to tetrahydrofuran and mixing them uniformly, adding 1H,1H,2H,2H-perfluorodecanethiol and mixing them uniformly, adding initiator, irradiating under ultraviolet light for 2 hours, adding to twice the volume of anhydrous ethanol for precipitation, filtering to obtain a solid, redissolving it in tetrahydrofuran, and then placing it in anhydrous ethanol for flocculation and repeating 3 times to obtain fluorinated phenylsilane resin.

[0036] Example 2: A method for processing precision stainless steel for a corrosion-resistant pneumatic cylinder, comprising the following steps:

[0037] Step 1: Austenitic stainless steel (316L austenitic stainless steel) was heated to 1150°C and kept at this temperature for 2 hours, forged at 900°C (forging ratio 3.5), solution treated at 1100°C for 1.5 hours, water quenched, machined, and nitrided at 530°C for 4 hours to obtain precision stainless steel A.

[0038] Step 2: Soak the precision stainless steel in acid A for 7 minutes, wash it, dry it, add it to the electrolyte for micro-arc oxidation for 8 minutes, immerse it in the modified composite sol sealing agent for 30 seconds, take it out, dry it at 50°C for 2 hours, heat it to 300°C at a rate of 2°C / min, keep it warm for 40 minutes, and repeat the sealing three times to obtain corrosion-resistant precision stainless steel for pneumatic cylinders;

[0039] The electrolyte raw materials include the following components: 10g / L sodium silicate, 5g / L potassium hydroxide, 1.5g / L cerium nitrate, and 1g / L modified graphene. The micro-arc oxidation process conditions are: duty cycle 30%, current density 4A / dm2, and operating frequency 400Hz.

[0040] The modified composite sol sealing agent is prepared by: adding a fluorinated-phenylsilane resin to a mixed solution of ethanol and toluene, uniformly mixing to obtain a mixed solution; adding aluminum nitrate to deionized water, uniformly mixing, adding nano zirconium oxide, and ultrasonically dispersing to obtain a mixed solution A; uniformly mixing tetraethyl orthosilicate, ethanol, and deionized water, adding hydrochloric acid to adjust the pH to 3, stirring for 1.5 hours, adding the mixed solution A, uniformly mixing for 2 hours, adjusting the pH to 6.5, adding a silane coupling agent-ethanol aqueous solution, uniformly mixing, slowly adding the mixed solution, uniformly mixing for 50 minutes, and aging for 4 hours to obtain the modified composite sol sealing agent;

[0041] The mass ratio of tetraethyl silicate, ethanol, and deionized water is 1:4:2; the mass ratio of aluminum nitrate, nano zirconium oxide, and tetraethyl silicate is 1:0.7:3; the amount of silane coupling agent added is 1.2wt%, including KH560 and tridecafluorooctyltrimethoxysilane in a mass ratio of 0.2:1; the volume ratio of ethanol and toluene is 3:2; and the amount of fluorinated-phenylsilane resin added is 7wt%;

[0042] The preparation method of fluorinated phenylsilane resin is as follows: (1) adding 0.1 parts of oxalic acid to 8 parts of deionized water and mixing them uniformly, adding 15 parts of phenyltrimethoxysilane and mixing them uniformly, stirring at 55°C for 5 hours, adding 6 parts of vinyltrimethoxysilane and 0.25 parts of dibutyltin dilaurate, heating to 90°C and reflux for 4 hours, removing the solvent, and obtaining vinyl-phenylsilane resin; (2) weighing vinyl-phenylsilane resin and 1H,1H,2H,2H-perfluorodecanethiol in a mass ratio of 1:0.4; adding vinyl-phenylsilane resin to tetrahydrofuran and mixing them uniformly, adding 1H,1H,2H,2H-perfluorodecanethiol and mixing them uniformly, adding initiator, irradiating under ultraviolet light for 2 hours, adding to twice the volume of anhydrous ethanol for precipitation, filtering to obtain a solid, redissolving it in tetrahydrofuran, and then placing it in anhydrous ethanol for flocculation and repeating 3 times to obtain fluorinated phenylsilane resin.

[0043] Example 3: A method for processing precision stainless steel for a corrosion-resistant pneumatic cylinder, comprising the following steps:

[0044] Step 1: Austenitic stainless steel (316L austenitic stainless steel) was heated to 1150°C and kept at this temperature for 2 hours, forged at 900°C (forging ratio 3.5), solution treated at 1100°C for 1.5 hours, water quenched, machined, and nitrided at 530°C for 4 hours to obtain precision stainless steel A.

[0045] Step 2: Soak the precision stainless steel in acid A for 7 minutes, wash it, dry it, add it to the electrolyte for micro-arc oxidation for 8 minutes, immerse it in the modified composite sol sealing agent for 30 seconds, take it out, dry it at 50°C for 2 hours, heat it to 300°C at a rate of 2°C / min, keep it warm for 40 minutes, and repeat the sealing three times to obtain corrosion-resistant precision stainless steel for pneumatic cylinders;

[0046] The electrolyte raw materials include the following components: 10g / L sodium silicate, 5g / L potassium hydroxide, 1.5g / L cerium nitrate, and 0.7g / L modified graphene; the process conditions of micro-arc oxidation are: duty cycle 30%, current density 4A / dm 2 , operating frequency 400Hz;

[0047] The modified composite sol sealing agent is prepared by: adding a fluorinated-phenylsilane resin to a mixed solution of ethanol and toluene, uniformly mixing to obtain a mixed solution; adding aluminum nitrate to deionized water, uniformly mixing, adding nano zirconium oxide, and ultrasonically dispersing to obtain a mixed solution A; uniformly mixing tetraethyl orthosilicate, ethanol, and deionized water, adding hydrochloric acid to adjust the pH to 3, stirring for 1.5 hours, adding the mixed solution A, uniformly mixing for 2 hours, adjusting the pH to 6.5, adding a silane coupling agent-ethanol aqueous solution, uniformly mixing, slowly adding the mixed solution, uniformly mixing for 50 minutes, and aging for 4 hours to obtain the modified composite sol sealing agent;

[0048] The mass ratio of tetraethyl silicate, ethanol, and deionized water is 1:4:2; the mass ratio of aluminum nitrate, nano zirconium oxide, and tetraethyl silicate is 1:0.7:3; the amount of silane coupling agent added is 1.2wt%, including KH560 and tridecafluorooctyltrimethoxysilane in a mass ratio of 0.2:1; the volume ratio of ethanol to toluene is (3-4):2; and the amount of fluorinated-phenylsilane resin added is 6wt%.

[0049] The preparation method of fluorinated phenylsilane resin is as follows: (1) adding 0.1 parts of oxalic acid to 8 parts of deionized water and mixing them uniformly, adding 15 parts of phenyltrimethoxysilane and mixing them uniformly, stirring at 55°C for 5 hours, adding 6 parts of vinyltrimethoxysilane and 0.25 parts of dibutyltin dilaurate, heating to 90°C and reflux for 4 hours, removing the solvent, and obtaining vinyl-phenylsilane resin; (2) weighing vinyl-phenylsilane resin and 1H,1H,2H,2H-perfluorodecanethiol in a mass ratio of 1:0.4; adding vinyl-phenylsilane resin to tetrahydrofuran and mixing them uniformly, adding 1H,1H,2H,2H-perfluorodecanethiol and mixing them uniformly, adding initiator, irradiating under ultraviolet light for 2 hours, adding to twice the volume of anhydrous ethanol for precipitation, filtering to obtain a solid, redissolving it in tetrahydrofuran, and then placing it in anhydrous ethanol for flocculation and repeating 3 times to obtain fluorinated phenylsilane resin.

[0050] Comparative Example 1 was based on Example 2, except that 1H,1H,2H,2H-perfluorodecanethiol was not added, and the remaining steps were the same;

[0051] Step 1: Austenitic stainless steel (316L austenitic stainless steel) was heated to 1150°C and kept at this temperature for 2 hours, forged at 900°C (forging ratio 3.5), solution treated at 1100°C for 1.5 hours, water quenched, machined, and nitrided at 530°C for 4 hours to obtain precision stainless steel A.

[0052] Step 2: Soak the precision stainless steel in acid A for 7 minutes, wash it, dry it, add it to the electrolyte for micro-arc oxidation for 8 minutes, immerse it in the modified composite sol sealing agent for 30 seconds, take it out, dry it at 50°C for 2 hours, heat it to 300°C at a rate of 2°C / min, keep it warm for 40 minutes, and repeat the sealing three times to obtain corrosion-resistant precision stainless steel for pneumatic cylinders;

[0053] The raw materials of the electrolyte include the following components: 10g / L sodium silicate, 5g / L potassium hydroxide, 1.5g / L cerium nitrate, and 1g / L modified graphene;

[0054] The modified composite sol sealing agent is prepared by: adding aluminum nitrate to deionized water and mixing uniformly, adding nano-zirconia and ultrasonically dispersing to obtain a mixed solution A; uniformly mixing tetraethyl orthosilicate, ethanol, and deionized water, adding hydrochloric acid to adjust the pH to 3 and stirring for 1.5 hours, adding the mixed solution A and uniformly mixing for 2 hours, adjusting the pH to 6.5, adding vinyl-phenyl silane resin (the amount of vinyl-phenyl silane resin added is 7wt%) and uniformly mixing for 50 minutes, and aging for 5 hours to obtain the modified composite sol sealing agent; wherein the mass ratio of tetraethyl silicate, ethanol, and deionized water is 1:4:2; and the mass ratio of aluminum nitrate, nano-zirconia, and tetraethyl silicate is 1:0.7:3.

[0055] The preparation method of vinyl-phenylsilane resin is as follows: (1) adding 0.1 parts of oxalic acid to 8 parts of deionized water and mixing them evenly, adding 15 parts of phenyltrimethoxysilane and mixing them evenly, stirring at 55°C for 5 hours, adding 6 parts of vinyltrimethoxysilane and 0.25 parts of dibutyltin dilaurate, heating to 90°C and reflux for 4 hours, removing the solvent, and obtaining vinyl-phenylsilane resin.

[0056] Comparative Example 2 was based on Example 2, except that 4-fluoro-3-trifluoromethylaniline was not added, and the remaining steps were the same;

[0057] Step 1: Austenitic stainless steel (316L austenitic stainless steel) was heated to 1150°C and kept at this temperature for 2 hours, forged at 900°C (forging ratio 3.5), solution treated at 1100°C for 1.5 hours, water quenched, machined, and nitrided at 530°C for 4 hours to obtain precision stainless steel A.

[0058] Step 2: Soak the precision stainless steel in acid A for 7 minutes, wash it, dry it, add it to the electrolyte for micro-arc oxidation for 8 minutes, immerse it in the modified composite sol sealing agent for 30 seconds, take it out, dry it at 50°C for 2 hours, heat it to 300°C at a rate of 2°C / min, keep it warm for 40 minutes, and repeat the sealing three times to obtain corrosion-resistant precision stainless steel for pneumatic cylinders;

[0059] The raw materials of the electrolyte include the following components: 10g / L sodium silicate, 5g / L potassium hydroxide, 1.5g / L cerium nitrate, and 1g / L modified graphene;

[0060] The preparation method of modified graphene is as follows: (1) adding 1.2 parts of KH560 to 15 parts of ethanol aqueous solution and mixing uniformly, adding 0.7 parts of graphene and ultrasonically dispersing, adjusting the pH to 4, stirring at 55°C for 5 hours, centrifuging, washing, and drying to obtain epoxidized graphene; (2) weighing epoxidized graphene and dopamine in a mass ratio of 1:0.2; adding epoxidized graphene to N,N-dimethylformamide and ultrasonically dispersing, adding dopamine, heating to 55°C under a nitrogen atmosphere and stirring for 3 hours, removing the solvent, and obtaining modified graphene.

[0061] Comparative Example 3 was based on Example 3, but without the addition of fluorinated phenylsilane resin;

[0062] Step 1: Austenitic stainless steel (316L austenitic stainless steel) was heated to 1150°C and kept at this temperature for 2 hours, forged at 900°C (forging ratio 3.5), solution treated at 1100°C for 1.5 hours, water quenched, machined, and nitrided at 530°C for 4 hours to obtain precision stainless steel A.

[0063] Step 2: Soak the precision stainless steel in acid A for 7 minutes, wash it, dry it, add it to the electrolyte for micro-arc oxidation for 8 minutes, immerse it in the modified composite sol sealing agent for 30 seconds, take it out, dry it at 50°C for 2 hours, heat it to 300°C at a rate of 2°C / min, keep it warm for 40 minutes, and repeat the sealing three times to obtain corrosion-resistant precision stainless steel for pneumatic cylinders;

[0064] The raw materials of the electrolyte include the following components: 10g / L sodium silicate, 5g / L potassium hydroxide, 1.5g / L cerium nitrate, and 1g / L modified graphene;

[0065] The modified composite sol sealing agent is prepared by: adding aluminum nitrate to deionized water and uniformly mixing, adding nano zirconium oxide and ultrasonically dispersing to obtain a mixed solution A; uniformly mixing tetraethyl orthosilicate, ethanol, and deionized water, adding hydrochloric acid to adjust the pH to 3 and stirring for 1.5 hours, adding the mixed solution A and uniformly mixing for 2 hours, adjusting the pH to 6.5, adding a silane coupling agent-ethanol aqueous solution and uniformly mixing, and aging for 4 hours to obtain the modified composite sol sealing agent;

[0066] Among them, the mass ratio of tetraethyl silicate, ethanol and deionized water is 1:4:2; the mass ratio of aluminum nitrate, nano zirconium oxide and tetraethyl silicate is 1:0.7:3; the added amount of silane coupling agent is 1.2wt%, including KH560 and tridecafluorooctyltrimethoxysilane in a mass ratio of 0.2:1.

[0067] Comparative Example 4 is based on Example 2 and is directly immersed in the unmodified composite glue;

[0068] Step 1: Austenitic stainless steel (316L austenitic stainless steel) was heated to 1150°C and kept at this temperature for 2 hours, forged at 900°C (forging ratio 3.5), solution treated at 1100°C for 1.5 hours, water quenched, machined, and nitrided at 530°C for 4 hours to obtain precision stainless steel A.

[0069] Step 2: Soak the precision stainless steel in acid A for 7 minutes, wash it, dry it, add it to the electrolyte for micro-arc oxidation for 8 minutes, immerse it in the modified composite sol sealing agent for 30 seconds, take it out, dry it at 50°C for 2 hours, heat it to 300°C at a rate of 2°C / min, keep it warm for 40 minutes, and repeat the sealing three times to obtain corrosion-resistant precision stainless steel for pneumatic cylinders;

[0070] The raw materials of the electrolyte include the following components: 10g / L sodium silicate, 5g / L potassium hydroxide, 1.5g / L cerium nitrate, and 1g / L modified graphene;

[0071] The preparation method of the composite sol sealing agent comprises the following steps: adding aluminum nitrate to deionized water and uniformly mixing to obtain a mixed solution A; uniformly mixing tetraethyl orthosilicate, ethanol, and deionized water, adding hydrochloric acid to adjust the pH to 3 and stirring for 1.5 hours, adding the mixed solution A and uniformly mixing for 2 hours, and aging for 5 hours to obtain the composite sol sealing agent; wherein the mass ratio of tetraethyl silicate, ethanol, and deionized water is 1:4:2; and the mass ratio of aluminum nitrate to tetraethyl silicate is 1:3.

[0072] Detection experiment; (1) Examples 1 to 3 and Comparative Examples 1 to 4 were soaked in 10% HCl solution for 3 days, taken out and cleaned, and KSCN was added to each corroded 10% HCl solution to observe the color change of the 10% HCl solution; if the solution did not turn red, it means that there was no Fe in the solution. 3+ Yes; after micro-arc oxidation and sealing treatment, most of the through-holes in the coating have been blocked, and the corrosive liquid cannot directly penetrate into the substrate, so the color of the solution has not changed significantly;

[0073] (2) Weight loss per unit area of ​​Examples 1 to 3 and Comparative Examples 1 to 4 after immersion in a 300°C NaCl molten salt environment for 48 hours;

[0074] Conclusion: Comparative Example 1 is based on Example 2, except that 1H,1H,2H,2H-perfluorodecanethiol is not added; this results in an increase in the weight loss per unit area, thereby reducing the corrosion resistance of Comparative Example 1; Comparative Example 2 is based on Example 2, except that 4-fluoro-3-trifluoromethylaniline is not added; this results in a decrease in the bonding force between the micro-arc oxidation layer and the modified composite adhesive sealing agent, thereby affecting the performance of Comparative Example 2; Comparative Example 3 is based on Example 3, except that fluorinated-phenylsilane resin is not added; this results in a decrease in permeability, corrosion resistance and heat resistance, thereby reducing the performance of Comparative Example 3; Comparative Example 4 is based on Example 2, and is directly immersed in the unmodified composite adhesive; this results in a decrease in the performance of Comparative Example 4.

[0075] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for processing precision stainless steel for corrosion-resistant pneumatic cylinders, characterized by: The following steps are included: Step 1: Heat the austenitic stainless steel to 1150-1200℃ and keep it for 2-3 hours, forge it at 850-950℃, solution treat it at 1050-1100℃ for 1-2 hours, water quench it, machine it, and nitride it at 520-550℃ for 4-5 hours to obtain precision stainless steel A. Step 2: The precision stainless steel A is pickled for 7-10 minutes, cleaned, dried, and then added to the electrolyte for micro-arc oxidation for 5-8 minutes, immersed in the modified composite sol sealing agent for 30-40 seconds, and removed for sealing to obtain corrosion-resistant precision stainless steel for pneumatic cylinders; The raw materials of the electrolyte include the following components: 8-12 g / L sodium silicate, 3-6 g / L potassium hydroxide, 1.5-3 g / L sodium titanate, and 0.7-1.2 g / L modified graphene; The preparation method of the modified graphene is as follows: (1) adding KH560 to an ethanol aqueous solution and uniformly mixing, adding graphene and ultrasonically dispersing, adjusting the pH to 4-5, stirring at 50-60° C. for 4-5 hours, centrifuging, washing, and drying to obtain epoxidized graphene; (2) adding epoxidized graphene to N,N-dimethylformamide and ultrasonically dispersing, adding dopamine and 4-fluoro-3-trifluoromethylaniline, heating to 50-60° C. and stirring for 2-3 hours under a nitrogen atmosphere, removing the solvent, and obtaining modified graphene; The raw materials of the epoxidized graphene include the following components: 1-1.5 parts of KH560, 15-20 parts of ethanol aqueous solution, and 0.7-1 parts of graphene, measured by mass; the mass ratio of the epoxidized graphene, dopamine, and 4-fluoro-3-trifluoromethylaniline is 1:(0.2-03):(0.4-0.6); The modified composite sol sealing agent is prepared by: adding a fluorinated-phenylsilane resin to a mixed solution of ethanol and toluene, uniformly mixing to obtain a mixed solution; adding aluminum nitrate to deionized water, uniformly mixing, adding nano-zirconium oxide and ultrasonically dispersing to obtain a mixed solution A; uniformly mixing tetraethyl orthosilicate, ethanol, and deionized water, adding hydrochloric acid to adjust the pH to 3-4, stirring for 1.5-2.5 hours, adding the mixed solution A, uniformly mixing for 1-2 hours, adjusting the pH to 6-7, adding a silane coupling agent-ethanol aqueous solution, uniformly mixing, slowly adding the mixed solution, uniformly mixing for 40-50 minutes, and aging for 3-5 hours to obtain the modified composite sol sealing agent; The preparation method of the fluorinated-phenylsilane resin is as follows: (1) adding oxalic acid to deionized water and mixing uniformly, adding phenyltrimethoxysilane and mixing uniformly, stirring at 50-55° C. for 5-6 hours, adding vinyltrimethoxysilane and dibutyltin dilaurate, heating to 90-95° C. and reflux for 4-5 hours, and rotary evaporation to obtain vinyl-phenylsilane resin; (2) adding vinyl-phenylsilane resin to tetrahydrofuran and mixing uniformly, adding 1H,1H,2H,2H-perfluorodecanethiol and mixing uniformly, adding an initiator, irradiating under ultraviolet light for 1-2 hours, adding to anhydrous ethanol for flocculation purification, and repeating 2-3 times to obtain fluorinated-phenylsilane resin.

2. The method for processing precision stainless steel for corrosion-resistant pneumatic cylinders according to claim 1, characterized in that: The mass ratio of the tetraethyl silicate, ethanol, and deionized water is 1:(3-4):(2-2.5); the mass ratio of the aluminum nitrate, nano zirconium oxide, and tetraethyl silicate is 1:(0.7-1.2):(2-3); The added amount of the silane coupling agent is 1.2-1.8 wt %, including KH560 and tridecafluorooctyltrimethoxysilane in a mass ratio of (0.2-0.3):1; the added amount of the fluorinated-phenylsilane resin is 5-10 wt %; and the volume ratio of the ethanol and toluene is (3-4):

2.

3. The method for processing precision stainless steel for corrosion-resistant pneumatic cylinders according to claim 1, characterized in that: The raw materials of the vinyl-phenylsilane resin include the following components: 0.06-0.1 parts of oxalic acid, 15-20 parts of phenyltrimethoxysilane, 6-8 parts of vinyltrimethoxysilane, 0.2-0.3 parts of dibutyltin dilaurate, and 7-8 parts of deionized water, calculated by mass; the mass ratio of the vinyl-phenylsilane resin to 1H,1H,2H,2H-perfluorodecanethiol is 1:(0.2-0.5).

4. The method for processing precision stainless steel for corrosion-resistant pneumatic cylinders according to claim 1, characterized in that: The sealing treatment process conditions are as follows: immersing in a modified composite sol sealing agent, drying at 40-50°C for 1-2 hours, heating to 300-320°C at a rate of 1-2°C / min, keeping warm for 30-40 minutes, and repeating 3-4 times; the micro-arc oxidation process conditions are as follows: a duty cycle of 20-40% and a current density of 4-6A / dm 2 , operating frequency 300~400Hz.

5. Precision stainless steel for corrosion-resistant pneumatic cylinders is prepared according to the processing method of precision stainless steel for corrosion-resistant pneumatic cylinders according to any one of claims 1 to 4.

Images