High-temperature-resistant stainless steel for ovens and method for manufacturing the same

Abstract

The present application relates to the technical field of stainless steel material, and particularly discloses a high-temperature-resistant stainless steel for ovens and a preparation method thereof. First, the stainless steel is passivated by using a sodium molybdate electrolyte to inhibit the migration of elements such as chromium in the stainless steel during use. Then, a titanium iron nitride layer and an aluminum titanium nitride / titanium silicon nitride layer are designed on the stainless steel. The two layers work together to transition the thermal expansion coefficient and enhance the high-temperature resistance. The element migration and diffusion are prevented. Finally, a porous magnesium titanate ceramic layer loaded with silver zinc antibacterial agent is deposited. The magnesium titanate ceramic itself has good high-temperature resistance and thermal shock resistance, and has a good thermal conductivity. After impregnating the antibacterial agent and sealing the pores, the magnesium titanate ceramic has good antibacterial performance.

Description

Technical Field

[0001] The present invention relates to the technical field of stainless steel materials, in particular to high-temperature resistant stainless steel for ovens and a preparation method thereof. Background Art

[0002] With the improvement of people's living standards, the popularity of kitchen appliances such as ovens in households is gradually increasing. As a household appliance that comes into direct contact with food and directly heats food, its safety has always been a concern for people. During the use of the oven, the stainless steel inside is not only affected by the high temperature caused by heating, but also by the corrosion caused by water vapor, grease, acid, salt, etc. in the food. Many unqualified stainless steel ovens will not only have defects such as pitting and micropores during use, breeding harmful bacteria, but also migrate heavy metal ions, affecting people's health.

[0003] A qualified oven must not only ensure that it does not release toxic and harmful substances at high temperatures, but its inner walls and other parts must also be smooth enough to prevent food residues from adhering to and breeding bacteria. In addition, its material should also be able to resist corrosion from acid, salt and other components in food. Therefore, the development of a stainless steel material with good high-temperature resistance and antibacterial properties and its application in food-grade equipment such as ovens and baking ovens will be of great help to the promotion and popularization of kitchen appliances such as ovens. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-temperature resistant stainless steel for ovens and a preparation method thereof, so as to solve the problems that stainless steel for ovens has poor high-temperature resistance, poor antibacterial property and is easy to breed bacteria.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for preparing high-temperature resistant stainless steel for ovens, specifically comprising:

[0007] Step 1: After sandblasting, the stainless steel surface is plasma activated and passivated with sodium molybdate electrolyte to obtain a pretreated stainless steel substrate;

[0008] Step 2: Using magnetron sputtering technology, a titanium iron nitride layer and an aluminum titanium nitride / nitrogen silicon titanium transition layer are sequentially deposited on the pretreated stainless steel substrate to obtain surface magnetron sputtering treated stainless steel;

[0009] Step 3: plasma spraying ceramic coating powder on the surface of magnetron sputtering treated stainless steel to prepare surface porous magnesium titanate ceramic stainless steel;

[0010] Step 4: The surface of the porous magnesium titanate ceramic stainless steel is immersed in an antibacterial impregnation liquid and then coated with a sealing agent to obtain high-temperature resistant stainless steel for ovens.

[0011] As a limitation of the present invention, in step 1, the preparation method of the sodium molybdate electrolyte is:

[0012] Add polyacrylamide to deionized water, stir evenly, then add nano-cerium dioxide, and ultrasonically disperse for 15-20 minutes to obtain a nano-cerium dioxide dispersion. Heat the deionized water to 50-60°C, add sodium molybdate, stir at 400-500 rpm for 10-15 minutes, then add trisodium citrate, continue stirring for 5-10 minutes, then add the nano-cerium dioxide dispersion, stir evenly, and adjust the pH to 8-9 to obtain a sodium molybdate electrolyte.

[0013] In the sodium molybdate electrolyte, the concentration of polyacrylamide is 0.1-1 g / L, the concentration of sodium molybdate is 100-110 g / L, the concentration of trisodium citrate is 25-35 g / L, and the concentration of nano-cerium dioxide is 2-5 g / L.

[0014] As a limitation of the present invention, the step 1 is specifically as follows:

[0015] The stainless steel surface is sandblasted, the sandblasting abrasive is nano-zirconium corundum, the sandblasting pressure is 0.5-0.6MPa, the sandblasting time is 3-5min, and after the sandblasting is completed, it is transferred to a plasma equipment reaction chamber, a mixed gas of argon, oxygen and hydrogen is introduced, and a power supply is started for plasma treatment, the power supply power is set to 500-550W, and the treatment time is 5-8min. After the treatment is completed, the oxygen and hydrogen are turned off, the power supply power is adjusted to 200-250W, and the treatment is continued for 1-2min. It is then transferred as an anode to a sodium molybdate electrolyte and treated at 40-45°C and 8-12V peak pulse voltage for 5-8min to obtain a pretreated stainless steel substrate.

[0016] During sandblasting, the abrasive is at 60-70° to the stainless steel surface, the volume ratio of argon, oxygen and hydrogen is (2-3):1:(0.04-0.06), and during electrolysis, the cathode is an iron plate.

[0017] Sandblasting is used to remove oxides and impurities on the surface of the stainless steel. After plasma activation, electrolyte passivation treatment is performed. The electrolyte contains sodium molybdate, trisodium citrate and cerium dioxide. Molybdate ions are reduced to molybdenum dioxide at the cathode, and hydroxide ions are generated and co-deposited with chromium ions to form chromium oxide, thereby forming a molybdenum oxide-chromium oxide solid solution that is deposited on the stainless steel surface, passivating the stainless steel and preventing chromium migration. Trisodium citrate can form a stable complex with trivalent chromium to prevent the conversion of trivalent chromium to hexavalent chromium. Cerium dioxide consumes dissolved oxygen through the valence cycle of cerium ions, inhibiting local corrosion and enhancing the corrosion resistance of the material. At the same time, it fills the micropores of the passivation film, making the passivation film on the surface of the stainless steel substrate denser.

[0018] As a limitation of the present invention, in step 2, when depositing the titanium iron nitride layer, the process parameters are: substrate temperature of 400-420°C, nitrogen flow rate of 20-30sccm, argon flow rate of 60-70sccm, power supply power of 7-8KW, bias voltage of (-80)-(-120)V, deposition time of 25-35min, and titanium iron nitride layer thickness of 0.8-1.0μm;

[0019] When depositing the aluminum titanium nitride / titanium silicon nitride layer, the process parameters are: the power of the aluminum titanium alloy target is 6-7KW, the nitrogen flow rate is 30-40sccm, the deposition time is 12-15s, the power of the titanium silicide target is 4-5KW, the nitrogen flow rate is 60-70sccm, the deposition time is 8-10s, and a total of 16-22 alternating depositions are performed. The thickness of the aluminum titanium nitride / titanium silicon nitride layer is 0.5-0.7μm.

[0020] The titanium-iron alloy target is bombarded and sputtered by high-energy plasma. The active nitrogen atoms dissociated from the plasma react with metal atoms, deposit on the surface of the stainless steel and undergo solid solution strengthening to form a nano-scale titanium nitride / iron nitride composite phase. The iron-titanium intermetallic compound strengthens the bonding performance of the coating, and the iron nitride (Fe4N) composite phase inhibits grain boundary migration at high temperatures.

[0021] Aluminum titanium nitride / silicon titanium nitride nano-laminates disperse stress and improve the thermal shock resistance of the material. The aluminum in the aluminum titanium nitride layer preferentially segregates to the grain boundaries to form a continuous aluminum oxide film, and the silicon nitride grain boundary phase of the silicon titanium nitride layer blocks the migration of antibacterial ions to the stainless steel matrix.

[0022] As a limitation of the present invention, in step 3, the preparation method of the ceramic coating powder is:

[0023] Aluminum chloride hexahydrate is added to deionized water, stirred at 60-70°C, and then ammonia water is added. The mixture is allowed to stand in the dark at room temperature for 60-72 hours to obtain aluminum sol. Ammonium bicarbonate is added to the aluminum sol, immersed for 20-30 minutes, and then taken out. The mixture is vacuum-dried at 60-70°C for 6-8 hours to obtain pore-forming agent powder. Magnesium titanate and the pore-forming agent are evenly mixed to obtain ceramic coating powder.

[0024] The mass ratio of aluminum chloride hexahydrate to ammonium bicarbonate is (24-26):(20-22); the mass ratio of magnesium titanate to the pore-forming agent is (7-8):(2-3).

[0025] The ammonium bicarbonate is impregnated with aluminum sol to form an alumina coating on the ammonium bicarbonate, thereby enhancing the stability of the ammonium bicarbonate and increasing the decomposition temperature of the pore-forming agent. This slows down the thermal decomposition rate of the pore-forming agent during the plasma spraying process and improves the pore uniformity of the ceramic coating.

[0026] As a limitation of the present invention, the step 3 is specifically as follows:

[0027] The surface magnetron sputtering treated stainless steel is placed in a plasma spraying device. After the substrate is preheated to 400-420°C, the ceramic coating powder is plasma sprayed on the surface magnetron sputtering treated stainless steel to form an 80-100μm porous magnesium titanate ceramic layer. The power supply is set to 35-40KW, the powder feeding rate is 30-35g / min, and the spraying distance is 60-100mm to obtain the surface porous magnesium titanate ceramic stainless steel.

[0028] As a limitation of the present invention, in step 4, the preparation method of the antibacterial impregnation solution is

[0029] Add nano zinc oxide to polyvinyl pyrrolidone ethanol dispersion, ultrasonically disperse for 20-30 minutes, add ethyl orthosilicate, stir evenly, add ammonia water dropwise, react at 40-50 ° C for 5-6 hours, and vacuum dry at 60-70 ° C for 3-4 hours to obtain silicon dioxide coated zinc oxide, add silicon dioxide coated zinc oxide to silver nitrate aqueous solution, adsorb at (-0.08)-(-0.09) MPa negative pressure for 20-30 minutes, let it stand for 1.5-2 hours, add sodium borohydride solution dropwise, and The reaction was carried out at 25-30°C for 20-30 minutes. After the reaction was completed, the mixture was centrifuged, washed with deionized water, and vacuum-dried at 60-70°C for 4-6 hours to obtain silver-zinc antibacterial particles. The deionized water was preheated to 40-45°C, and the silver-zinc antibacterial particles were added. After ultrasonic dispersion for 20-30 minutes, silica sol, zinc molybdate, and nano-zirconium dioxide were added in sequence. The mixture was stirred at 800-1000 rpm for 30-45 minutes to form a suspension. The suspension was allowed to stand in a water bath at 40-45°C for 1-3 hours to obtain an antibacterial impregnation solution.

[0030] The polyvinylpyrrolidone ethanol dispersion contains 2-4wt% polyvinylpyrrolidone; the silver nitrate aqueous solution contains 8-10wt% silver nitrate; the sodium borohydride solution contains 1-3wt% sodium borohydride; the mass ratio of nano-zinc oxide, ethyl orthosilicate, silver nitrate aqueous solution and sodium borohydride solution is (5-6):(11-13):(10-12):(10-12); and in the antibacterial impregnation solution, the mass ratio of silver-zinc antibacterial particles, silica sol, zinc molybdate and nano-zirconium dioxide is (10-15):(8-10):(3.5-4.5):(2.5-3.5).

[0031] Nano-zinc oxide is coated with silica, and silver nanoparticles are generated in situ in the pores of the silica shell through the reaction of silver nitrate and sodium borohydride. The silica shell slowly releases silver ions and zinc ions through the mesoporous structure, achieving synergistic and long-lasting antibacterial effect.

[0032] As a limitation of the present invention, in step 4, the preparation method of the sealing agent is:

[0033] Potassium silicate and aluminum dihydrogen phosphate were added to deionized water, stirred evenly, and then silica sol, boehmite and nano-cerium dioxide were added in sequence. The mixture was ultrasonically dispersed for 20-30 minutes, heated in a water bath at 25-30°C, and aged at 100-200 rpm for 20-24 hours to obtain a sealing agent.

[0034] In the sealing agent, the mass ratio of potassium silicate, aluminum dihydrogen phosphate, silica sol, boehmite and nano-cerium dioxide is (3-5):(8-10):(25-35):(3-7):(1.5-2.5).

[0035] As a limitation of the present invention, the step 4 is specifically as follows:

[0036] The surface porous magnesium titanate ceramic stainless steel is added to the antibacterial impregnation solution, impregnated at 60-70°C and (-0.08)-(-0.09) MPa negative pressure for 30-40 minutes, dried at 70-80°C for 1-2 hours, and then heated to 650-670°C under nitrogen protection and sintered for 30-45 minutes. After sintering, it is cooled to room temperature and coated with a sealing agent with a wet film thickness of 8-10 μm. After coating, it is cured at 80-100°C for 20-30 minutes, 120-140°C for 20-30 minutes, and 750-770°C for 10-20 minutes to obtain high-temperature resistant stainless steel for oven.

[0037] The antibacterial impregnation solution contains silver-zinc antibacterial particles, silica sol, zinc molybdate and nano-zirconium dioxide. The ceramic surface attracts the silver-zinc antibacterial particles and fixes them in the pores through electrostatic adsorption. The silica sol condenses with the hydroxyl groups on the ceramic surface and fixes them. The nano-silicon dioxide particles fill the micropores and reduce the porosity. When zinc molybdate is sintered at 650℃, it produces molybdenum trioxide melt to fix the antibacterial particles and fill the pores. Zirconium dioxide transforms from tetragonal phase to monoclinic phase at high temperature to absorb stress, anchoring the antibacterial particles while preventing the ceramic coating from cracking. The sealing agent contains potassium silicate, aluminum dihydrogen phosphate, silica sol, boehmite and nano-cerium dioxide. Aluminum dihydrogen phosphate is sintered at 80℃. Dehydration and cross-linking at -120℃ form an aluminum phosphate network, which closes submicron-level pores. Phosphate complexes silver ions and inhibits high-temperature oxidation of silver ions. Nano-silica particles in the silica sol sinter and shrink, filling the gaps in the aluminum phosphate network and further reducing the porosity. Potassium silicate melts during the sintering process to form a potassium oxide-silicon dioxide-alumina low-melting system, which flows to fill the remaining pores. Aluminum phosphate and silicon dioxide form a transition layer at the interface, which improves the bonding between the sealer and the ceramic coating. Boehmite undergoes a phase change during the sintering process and is converted into α-alumina to fill the micropores, reducing the porosity and improving the wear resistance of the coating.

[0038] A high-temperature resistant stainless steel for an oven is prepared by any of the above-mentioned preparation methods.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention adopts sodium molybdate electrolyte to passivate the stainless steel substrate. Molybdate ions in the electrolyte co-precipitate with chromium ions to form a molybdenum oxide-chromium oxide solid solution that is deposited on the stainless steel surface, passivating the stainless steel and preventing chromium migration. Trisodium citrate can form a stable complex with trivalent chromium to prevent the trivalent chromium from converting to more toxic hexavalent chromium. Cerium dioxide makes the passivation film denser.

[0041] The present invention magnetron sputters a titanium iron nitride layer and an aluminum titanium nitride / silicon titanium nitride layer on a stainless steel substrate. The two layers work synergistically to achieve a gradual transition of the thermal expansion coefficient from the stainless steel substrate to the antibacterial ceramic layer; inhibit grain boundary migration at high temperatures, thereby improving the high-temperature resistance of the material; and form an element diffusion barrier to prevent the mutual migration and diffusion of elements such as iron and chromium in the substrate and elements such as copper in the antibacterial ceramic layer.

[0042] The present invention synthesizes a porous magnesium titanate ceramic layer. The magnesium titanate ceramic itself has good high temperature resistance, thermal shock resistance, and good thermal conductivity. After being impregnated with an antibacterial agent and sealed, it is given good antibacterial properties. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. The terms used in the embodiments are to describe specific embodiments, rather than to limit the scope of protection of the present invention. The dosages in the embodiments are for laboratory tests and can be scaled up in equal proportions. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0044] XM-19 stainless steel (Cr: 21.8wt%, Ni: 12.5wt%, Mn: 5.2wt%, Mo: 2.1wt%, Cu: 0.15wt%, N: 0.3wt%, Si: 0.4wt%, P: 0.025wt%, S: 0.005wt%, balance iron), nano-cerium dioxide (particle size: 20nm±3nm), nano-zirconium corundum (particle size: 50±5nm), polyacrylamide (Mw: 500000-800000, AM residue ≤0.05wt%), titanium-iron alloy target (Ti: 60wt%, Fe: 40wt%), aluminum-titanium alloy target (Al: 50wt%, Ti: 50wt%), magnesium titanate (particle size: 30μm), polyvinyl pyrrolidone (Mw: 40000-50000), nano-zinc oxide (particle size: 50±5nm), boehmite (particle size: 100nm, specific surface area: 200m 2 / g), silica sol (SiO2: 40wt%, pH = 9), nano zirconium dioxide (particle size: 20nm, tetragonal phase).

[0045] Example 1: A method for preparing high-temperature resistant stainless steel for ovens, specifically:

[0046] Step 1: Add 0.1g polyacrylamide to 50mL deionized water, stir well, add 2g nano-cerium dioxide, and ultrasonically disperse for 20min to obtain a nano-cerium dioxide dispersion. Heat 800mL deionized water to 50°C, add 103g sodium molybdate, stir at 500rpm for 10min, then add 26g trisodium citrate. Continue stirring for 5min and then add the nano-cerium dioxide dispersion. After stirring well, adjust the pH to 8.5 and dilute to 1L to obtain a sodium molybdate electrolyte.

[0047] Step 2: The surface of XM-19 stainless steel was sandblasted. The sandblasting abrasive was nano-zirconium corundum. The sandblasting pressure was 0.6 MPa and the sandblasting time was 3 min. During sandblasting, the abrasive was 70° to the stainless steel surface. After sandblasting, it was transferred to the reaction chamber of the plasma equipment, and a mixture of argon, oxygen and hydrogen (volume ratio of 3:1:0.05) was introduced. The power supply was started for plasma treatment, the power supply power was set to 500 W, and the treatment time was 8 min. After the treatment was completed, the oxygen and hydrogen were turned off, the power supply power was adjusted to 200 W, and the treatment was continued for 2 min. It was then transferred as an anode to a sodium molybdate electrolyte, with an iron plate as the cathode, and treated at 40 ° C and a peak pulse voltage of 10 V for 8 min to obtain a pretreated stainless steel substrate;

[0048] Step 3: Place the pretreated stainless steel substrate into the reaction chamber of the magnetron sputtering equipment, seal the reaction chamber, preheat the substrate temperature to 400 °C, and evacuate to 5×10 -4 Pa, introduce a mixture of nitrogen and argon, set the nitrogen flow rate to 20sccm, the argon flow rate to 60sccm, start the titanium-iron alloy target DC power supply, deposit a 0.8μm titanium-iron nitride layer, set the power supply power to 8KW, the bias voltage to -120V, and the deposition time to 27min, turn off the titanium-iron alloy target power supply, start the aluminum-titanium alloy target DC power supply and the titanium silicide target DC power supply, alternately deposit 0.5μm aluminum titanium nitride / nitrogen silicon titanium layer, set the aluminum-titanium alloy target power supply power to 6KW, the nitrogen flow rate to 30sccm, and the deposition time to 12s, the titanium silicide target power supply power to 4KW, the nitrogen flow rate to 60sccm, and the deposition time to 8s, and perform alternating deposition 16 times to obtain surface magnetron sputtering treated stainless steel;

[0049] Step 4: Add 241.5 g of aluminum chloride hexahydrate to 1 L of deionized water, stir evenly at 60° C., add 145 mL of ammonia water, and allow to stand in the dark at room temperature for 72 hours to obtain an aluminum sol. Add 200 g of ammonium bicarbonate to the aluminum sol, soak for 30 minutes, then take out and vacuum dry at 60° C. for 8 hours to obtain a pore-forming agent. Mix magnesium titanate and the pore-forming agent evenly at a mass ratio of 7:3 to obtain a ceramic coating powder.

[0050] Step 5: Place the surface magnetron sputtering treated stainless steel into a plasma spraying device. After preheating the substrate to 400°C, plasma spray the ceramic coating powder onto the surface magnetron sputtering treated stainless steel to form a 100 μm porous magnesium titanate ceramic layer. Set the power supply to 40 kW, the powder feeding rate to 35 g / min, and the spraying distance to 60 mm to obtain surface porous magnesium titanate ceramic stainless steel.

[0051] Step 6: Add 50g of nano zinc oxide to 500g of 2wt% polyvinyl pyrrolidone ethanol dispersion, ultrasonically disperse for 30min, add 110g of ethyl orthosilicate, stir evenly, dropwise add 60mL of ammonia water, react at 40℃ for 6h, and vacuum dry at 60℃ for 4h to obtain silica-coated zinc oxide. Add silica-coated zinc oxide to 100g of 8.5wt% silver nitrate aqueous solution, adsorb at -0.09MPa negative pressure for 30min, let stand for 2h, and dropwise add 100g of 1 .2wt% sodium borohydride solution, react at 25℃ for 30min, centrifuge after the reaction, wash with deionized water, and vacuum dry at 60℃ for 6h to obtain silver-zinc antibacterial particles, preheat 780g deionized water to 40℃, add 100g silver-zinc antibacterial particles, ultrasonically disperse for 30min, then add 80g silica sol, 35g zinc molybdate and 25g nano zirconium dioxide in sequence, stir at 800rpm for 45min to form a suspension, and let it stand in a 40℃ water bath for 2h to obtain an antibacterial impregnation solution;

[0052] Step 7: Add 30g potassium silicate and 80g aluminum dihydrogen phosphate to 500g deionized water, stir evenly, then add 250g silica sol, 30g boehmite and 15g nano-cerium dioxide in turn, ultrasonically disperse for 30min, heat in a water bath at 25℃, and mature at 100rpm for 24h to obtain a sealing agent. Add the surface porous magnesium titanate ceramic stainless steel to the antibacterial impregnation solution, immerse at 60℃ and -0.09MPa negative pressure for 30min, dry at 80℃ for 1h, then heat to 650℃ under nitrogen protection and sinter for 45min. After sintering, cool to room temperature, apply the sealing agent, and the wet film thickness is 8μm. After coating, cure at 80℃ for 30min, 120℃ for 30min, and 750℃ for 20min to obtain high-temperature resistant stainless steel for oven.

[0053] Example 2: A method for preparing high-temperature resistant stainless steel for ovens, specifically:

[0054] Step 1: Add 0.1g polyacrylamide to 50mL deionized water, stir well, add 2g nano-cerium dioxide, and ultrasonically disperse for 20min to obtain a nano-cerium dioxide dispersion. Heat 800mL deionized water to 50°C, add 106g sodium molybdate, stir at 500rpm for 10min, then add 26g trisodium citrate. Continue stirring for 5min and then add the nano-cerium dioxide dispersion. After stirring well, adjust the pH to 8.5 and dilute to 1L to obtain a sodium molybdate electrolyte.

[0055] Step 2: The surface of XM-19 stainless steel was sandblasted. The sandblasting abrasive was nano-zirconium corundum. The sandblasting pressure was 0.6 MPa and the sandblasting time was 3 min. During sandblasting, the abrasive was 70° to the stainless steel surface. After sandblasting, it was transferred to the reaction chamber of the plasma equipment, and a mixture of argon, oxygen and hydrogen (volume ratio of 3:1:0.05) was introduced. The power supply was started for plasma treatment, the power supply power was set to 500 W, and the treatment time was 8 min. After the treatment was completed, the oxygen and hydrogen were turned off, the power supply power was adjusted to 200 W, and the treatment was continued for 2 min. It was then transferred as an anode to a sodium molybdate electrolyte, with an iron plate as the cathode, and treated at 40 ° C and a peak pulse voltage of 10 V for 8 min to obtain a pretreated stainless steel substrate;

[0056] Step 3: Place the pretreated stainless steel substrate into the reaction chamber of the magnetron sputtering equipment, seal the reaction chamber, preheat the substrate temperature to 400 °C, and evacuate to 5×10 -4 Pa, introduce a mixture of nitrogen and argon, set the nitrogen flow rate to 25sccm, the argon flow rate to 65sccm, start the titanium-iron alloy target DC power supply, deposit a 0.9μm titanium-iron nitride layer, set the power supply power to 8KW, the bias voltage to -120V, and the deposition time to 31min, turn off the titanium-iron alloy target power supply, start the aluminum-titanium alloy target DC power supply and the titanium silicide target DC power supply, alternately deposit 0.6μm aluminum titanium nitride / nitrogen silicon titanium layer, set the aluminum-titanium alloy target power supply power to 6KW, the nitrogen flow rate to 35sccm, and the deposition time to 13s, the titanium silicide target power supply power to 4KW, the nitrogen flow rate to 65sccm, and the deposition time to 9s, and alternately deposit 19 times to obtain surface magnetron sputtering treated stainless steel;

[0057] Step 4: Add 241.5 g of aluminum chloride hexahydrate to 1 L of deionized water, stir evenly at 60° C., add 145 mL of ammonia water, and allow to stand in the dark at room temperature for 72 hours to obtain an aluminum sol. Add 200 g of ammonium bicarbonate to the aluminum sol, soak for 30 minutes, then take out and vacuum dry at 60° C. for 8 hours to obtain a pore-forming agent. Mix magnesium titanate and the pore-forming agent evenly at a mass ratio of 7:3 to obtain a ceramic coating powder.

[0058] Step 5: Place the surface magnetron sputtering treated stainless steel into a plasma spraying device. After preheating the substrate to 400°C, plasma spray the ceramic coating powder onto the surface magnetron sputtering treated stainless steel to form a 100 μm porous magnesium titanate ceramic layer. Set the power supply to 40 kW, the powder feeding rate to 35 g / min, and the spraying distance to 60 mm to obtain surface porous magnesium titanate ceramic stainless steel.

[0059] Step 6: Add 50g of nano zinc oxide to 500g of 2wt% polyvinyl pyrrolidone ethanol dispersion, ultrasonically disperse for 30min, add 110g of ethyl orthosilicate, stir evenly, dropwise add 60mL of ammonia water, react at 40℃ for 6h, and vacuum dry at 60℃ for 4h to obtain silica-coated zinc oxide. Add silica-coated zinc oxide to 100g of 8.5wt% silver nitrate aqueous solution, adsorb at -0.09MPa negative pressure for 30min, let stand for 2h, and dropwise add 100g of 1 .2wt% sodium borohydride solution, react at 25℃ for 30min, centrifuge after the reaction, wash with deionized water, and vacuum dry at 60℃ for 6h to obtain silver-zinc antibacterial particles, preheat 780g deionized water to 40℃, add 120g silver-zinc antibacterial particles, ultrasonically disperse for 30min, then add 90g silica sol, 40g zinc molybdate and 30g nano zirconium dioxide in sequence, stir at 800rpm for 45min to form a suspension, and let it stand in a 40℃ water bath for 2h to obtain an antibacterial impregnation solution;

[0060] Step 7: Add 40g potassium silicate and 90g aluminum dihydrogen phosphate to 500g deionized water, stir evenly, then add 300g silica sol, 50g boehmite and 20g nano-cerium dioxide in turn, ultrasonically disperse for 30min, heat in a water bath at 25℃, and mature at 100rpm for 24h to obtain a sealing agent. Add the surface porous magnesium titanate ceramic stainless steel to the antibacterial impregnation solution, immerse at 60℃ and -0.09MPa negative pressure for 30min, dry at 80℃ for 1h, then heat to 650℃ under nitrogen protection and sinter for 45min. After sintering, cool to room temperature, apply the sealing agent, and the wet film thickness is 9μm. After coating, cure at 80℃ for 30min, 120℃ for 30min, and 750℃ for 20min to obtain high-temperature resistant stainless steel for oven.

[0061] Example 3: A method for preparing high-temperature resistant stainless steel for ovens, specifically comprising:

[0062] Step 1: Add 0.1 g of polyacrylamide to 50 mL of deionized water, stir well, add 2 g of nano-cerium dioxide, and ultrasonically disperse for 20 minutes to obtain a nano-cerium dioxide dispersion. Heat 800 mL of deionized water to 50°C, add 109 g of sodium molybdate, stir at 500 rpm for 10 minutes, then add 26 g of trisodium citrate. Continue stirring for 5 minutes, then add the nano-cerium dioxide dispersion, stir well, adjust the pH to 8.5, and dilute to 1 L to obtain a sodium molybdate electrolyte.

[0063] Step 2: The surface of XM-19 stainless steel was sandblasted. The sandblasting abrasive was nano-zirconium corundum. The sandblasting pressure was 0.6 MPa and the sandblasting time was 3 min. During sandblasting, the abrasive was 70° to the stainless steel surface. After sandblasting, it was transferred to the reaction chamber of the plasma equipment, and a mixture of argon, oxygen and hydrogen (volume ratio of 3:1:0.05) was introduced. The power supply was started for plasma treatment, the power supply power was set to 500 W, and the treatment time was 8 min. After the treatment was completed, the oxygen and hydrogen were turned off, the power supply power was adjusted to 200 W, and the treatment was continued for 2 min. It was then transferred as an anode to a sodium molybdate electrolyte, with an iron plate as the cathode, and treated at 40 ° C and a peak pulse voltage of 10 V for 8 min to obtain a pretreated stainless steel substrate;

[0064] Step 3: Place the pretreated stainless steel substrate into the reaction chamber of the magnetron sputtering equipment, seal the reaction chamber, preheat the substrate temperature to 400 °C, and evacuate to 5×10 -4 Pa, introduce a mixture of nitrogen and argon, set the nitrogen flow rate to 30sccm, the argon flow rate to 70sccm, start the titanium-iron alloy target DC power supply, deposit a 1.0μm titanium-iron nitride layer, set the power supply power to 8KW, the bias voltage to -120V, and the deposition time to 32min, turn off the titanium-iron alloy target power supply, start the aluminum-titanium alloy target DC power supply and the titanium silicide target DC power supply, alternately deposit 0.7μm aluminum titanium nitride / nitrogen silicon titanium layer, set the aluminum-titanium alloy target power supply power to 6KW, the nitrogen flow rate to 40sccm, the deposition time to 15s, the titanium silicide target power supply power to 4KW, the nitrogen flow rate to 70sccm, the deposition time to 10s, and perform alternating deposition 22 times to obtain surface magnetron sputtering treated stainless steel;

[0065] Step 4: Add 241.5 g of aluminum chloride hexahydrate to 1 L of deionized water, stir evenly at 60° C., add 145 mL of ammonia water, and allow to stand in the dark at room temperature for 72 hours to obtain an aluminum sol. Add 200 g of ammonium bicarbonate to the aluminum sol, soak for 30 minutes, then take out and vacuum dry at 60° C. for 8 hours to obtain a pore-forming agent. Mix magnesium titanate and the pore-forming agent evenly at a mass ratio of 7:3 to obtain a ceramic coating powder.

[0066] Step 5: Place the surface magnetron sputtering treated stainless steel into a plasma spraying device. After preheating the substrate to 400°C, plasma spray the ceramic coating powder onto the surface magnetron sputtering treated stainless steel to form a 100 μm porous magnesium titanate ceramic layer. Set the power supply to 40 kW, the powder feeding rate to 35 g / min, and the spraying distance to 60 mm to obtain surface porous magnesium titanate ceramic stainless steel.

[0067] Step 6: Add 50g of nano zinc oxide to 500g of 2wt% polyvinyl pyrrolidone ethanol dispersion, ultrasonically disperse for 30min, add 110g of ethyl orthosilicate, stir evenly, dropwise add 60mL of ammonia water, react at 40℃ for 6h, and vacuum dry at 60℃ for 4h to obtain silica-coated zinc oxide. Add silica-coated zinc oxide to 100g of 8.5wt% silver nitrate aqueous solution, adsorb at -0.09MPa negative pressure for 30min, let stand for 2h, and dropwise add 100g of 1 .2wt% sodium borohydride solution, react at 25℃ for 30min, centrifuge after the reaction, wash with deionized water, and vacuum dry at 60℃ for 6h to obtain silver-zinc antibacterial particles, preheat 780g deionized water to 40℃, add 150g silver-zinc antibacterial particles, ultrasonically disperse for 30min, then add 100g silica sol, 45g zinc molybdate and 35g nano zirconium dioxide in sequence, stir at 800rpm for 45min to form a suspension, and let it stand in a 40℃ water bath for 2h to obtain an antibacterial impregnation solution;

[0068] Step 7: Add 50g potassium silicate and 100g aluminum dihydrogen phosphate to 500g deionized water, stir evenly, then add 350g silica sol, 70g boehmite and 25g nano-cerium dioxide in turn, ultrasonically disperse for 30min, heat in a water bath at 25℃, and mature at 100rpm for 24h to obtain a sealing agent. Add the surface porous magnesium titanate ceramic stainless steel to the antibacterial impregnation solution, immerse at 60℃ and -0.09MPa negative pressure for 30min, dry at 80℃ for 1h, then heat to 650℃ under nitrogen protection and sinter for 45min. After sintering, cool to room temperature, apply the sealing agent, and the wet film thickness is 10μm. After coating, cure at 80℃ for 30min, 120℃ for 30min, and 750℃ for 20min to obtain high-temperature resistant stainless steel for oven.

[0069] Based on Example 1, control experiments were conducted, specifically Comparative Example 1, Comparative Example 2, and Comparative Example 3, as described below:

[0070] Comparative Example 1: This comparative example relates to a method for preparing high-temperature resistant stainless steel for ovens. The difference from Example 1 is that the stainless steel is not electrolytically passivated. Specifically,

[0071] Step 1: The surface of XM-19 stainless steel was sandblasted. The sandblasting abrasive was nano-zirconium corundum. The sandblasting pressure was 0.6 MPa and the sandblasting time was 3 min. During sandblasting, the abrasive was at 70° to the stainless steel surface. After sandblasting, the surface was transferred to the plasma equipment reaction chamber. A mixture of argon, oxygen and hydrogen (volume ratio of 3:1:0.05) was introduced. The power supply was started for plasma treatment. The power supply was set to 500 W and the treatment time was 8 min. After the treatment was completed, the oxygen and hydrogen were turned off, the power supply was adjusted to 200 W, and the treatment was continued for 2 min to obtain a pretreated stainless steel substrate.

[0072] Step 2: Place the pretreated stainless steel substrate into the reaction chamber of the magnetron sputtering equipment, seal the reaction chamber, preheat the substrate temperature to 400°C, and evacuate to 5×10 -4 Pa, introduce a mixture of nitrogen and argon, set the nitrogen flow rate to 20sccm, the argon flow rate to 60sccm, start the titanium-iron alloy target DC power supply, deposit a 0.8μm titanium-iron nitride layer, set the power supply power to 8KW, the bias voltage to -120V, and the deposition time to 27min, turn off the titanium-iron alloy target power supply, start the aluminum-titanium alloy target DC power supply and the titanium silicide target DC power supply, alternately deposit 0.5μm aluminum titanium nitride / nitrogen silicon titanium layer, set the aluminum-titanium alloy target power supply power to 6KW, the nitrogen flow rate to 30sccm, and the deposition time to 12s, the titanium silicide target power supply power to 4KW, the nitrogen flow rate to 60sccm, and the deposition time to 8s, and perform alternating deposition 16 times to obtain surface magnetron sputtering treated stainless steel;

[0073] Step 3: Add 241.5 g of aluminum chloride hexahydrate to 1 L of deionized water, stir evenly at 60° C., add 145 mL of ammonia water, and allow to stand in the dark at room temperature for 72 hours to obtain an aluminum sol. Add 200 g of ammonium bicarbonate to the aluminum sol, soak for 30 minutes, then take out and vacuum dry at 60° C. for 8 hours to obtain a pore-forming agent. Mix magnesium titanate and the pore-forming agent evenly at a mass ratio of 7:3 to obtain a ceramic coating powder.

[0074] Step 4: Place the surface magnetron sputtering treated stainless steel into a plasma spraying device. After preheating the substrate to 400°C, plasma spray the ceramic coating powder onto the surface magnetron sputtering treated stainless steel to form a 100 μm porous magnesium titanate ceramic layer. Set the power supply to 40 kW, the powder feeding rate to 35 g / min, and the spraying distance to 60 mm to obtain surface porous magnesium titanate ceramic stainless steel.

[0075] Step 5: Add 50g of nano zinc oxide to 500g of 2wt% polyvinyl pyrrolidone ethanol dispersion, ultrasonically disperse for 30min, add 110g of ethyl orthosilicate, stir evenly, dropwise add 60mL of ammonia water, react at 40℃ for 6h, and vacuum dry at 60℃ for 4h to obtain silica-coated zinc oxide. Add silica-coated zinc oxide to 100g of 8.5wt% silver nitrate aqueous solution, adsorb at -0.09MPa negative pressure for 30min, let stand for 2h, and dropwise add 100g of 1 .2wt% sodium borohydride solution, react at 25℃ for 30min, centrifuge after the reaction, wash with deionized water, and vacuum dry at 60℃ for 6h to obtain silver-zinc antibacterial particles, preheat 780g deionized water to 40℃, add 100g silver-zinc antibacterial particles, ultrasonically disperse for 30min, then add 80g silica sol, 35g zinc molybdate and 25g nano zirconium dioxide in sequence, stir at 800rpm for 45min to form a suspension, and let it stand in a 40℃ water bath for 2h to obtain an antibacterial impregnation solution;

[0076] Step 6: Add 30g potassium silicate and 80g aluminum dihydrogen phosphate to 500g deionized water, stir evenly, then add 250g silica sol, 30g boehmite and 15g nano-cerium dioxide in turn, ultrasonically disperse for 30min, heat in a water bath at 25℃, and mature at 100rpm for 24h to obtain a sealing agent. Add the surface porous magnesium titanate ceramic stainless steel to the antibacterial impregnation solution, immerse at 60℃ and -0.09MPa negative pressure for 30min, dry at 80℃ for 1h, then heat to 650℃ under nitrogen protection and sinter for 45min. After sintering, cool to room temperature, apply the sealing agent, and the wet film thickness is 8μm. After coating, cure at 80℃ for 30min, 120℃ for 30min, and 750℃ for 20min to obtain high-temperature resistant stainless steel for oven.

[0077] Comparative Example 2: This comparative example relates to a method for preparing high-temperature resistant stainless steel for ovens. The difference from Example 1 is that no magnetron sputtering transition layer is used. Specifically,

[0078] Step 1: Add 0.1g polyacrylamide to 50mL deionized water, stir well, add 2g nano-cerium dioxide, and ultrasonically disperse for 20min to obtain a nano-cerium dioxide dispersion. Heat 800mL deionized water to 50°C, add 103g sodium molybdate, stir at 500rpm for 10min, then add 26g trisodium citrate. Continue stirring for 5min and then add the nano-cerium dioxide dispersion. After stirring well, adjust the pH to 8.5 and dilute to 1L to obtain a sodium molybdate electrolyte.

[0079] Step 2: The surface of XM-19 stainless steel was sandblasted. The sandblasting abrasive was nano-zirconium corundum. The sandblasting pressure was 0.6 MPa and the sandblasting time was 3 min. During sandblasting, the abrasive was 70° to the stainless steel surface. After sandblasting, it was transferred to the reaction chamber of the plasma equipment, and a mixture of argon, oxygen and hydrogen (volume ratio of 3:1:0.05) was introduced. The power supply was started for plasma treatment, the power supply power was set to 500 W, and the treatment time was 8 min. After the treatment was completed, the oxygen and hydrogen were turned off, the power supply power was adjusted to 200 W, and the treatment was continued for 2 min. It was then transferred as an anode to a sodium molybdate electrolyte, with an iron plate as the cathode, and treated at 40 ° C and a peak pulse voltage of 10 V for 8 min to obtain a pretreated stainless steel substrate;

[0080] Step 3: Add 241.5 g of aluminum chloride hexahydrate to 1 L of deionized water, stir evenly at 60° C., add 145 mL of ammonia water, and allow to stand in the dark at room temperature for 72 hours to obtain an aluminum sol. Add 200 g of ammonium bicarbonate to the aluminum sol, soak for 30 minutes, then take out and vacuum dry at 60° C. for 8 hours to obtain a pore-forming agent. Mix magnesium titanate and the pore-forming agent evenly at a mass ratio of 7:3 to obtain a ceramic coating powder.

[0081] Step 4: Place the pretreated stainless steel substrate into a plasma spraying device. After preheating the substrate to 400°C, plasma spray the ceramic coating powder onto the pretreated stainless steel substrate to form a 100 μm porous magnesium titanate ceramic layer. Set the power supply to 40 kW, the powder feeding rate to 35 g / min, and the spraying distance to 60 mm to obtain surface porous magnesium titanate ceramic stainless steel.

[0082] Step 5: Add 50g of nano zinc oxide to 500g of 2wt% polyvinyl pyrrolidone ethanol dispersion, ultrasonically disperse for 30min, add 110g of ethyl orthosilicate, stir evenly, dropwise add 60mL of ammonia water, react at 40℃ for 6h, and vacuum dry at 60℃ for 4h to obtain silica-coated zinc oxide. Add silica-coated zinc oxide to 100g of 8.5wt% silver nitrate aqueous solution, adsorb at -0.09MPa negative pressure for 30min, let stand for 2h, and dropwise add 100g of 1 .2wt% sodium borohydride solution, react at 25℃ for 30min, centrifuge after the reaction, wash with deionized water, and vacuum dry at 60℃ for 6h to obtain silver-zinc antibacterial particles, preheat 780g deionized water to 40℃, add 100g silver-zinc antibacterial particles, ultrasonically disperse for 30min, then add 80g silica sol, 35g zinc molybdate and 25g nano zirconium dioxide in sequence, stir at 800rpm for 45min to form a suspension, and let it stand in a 40℃ water bath for 2h to obtain an antibacterial impregnation solution;

[0083] Step 6: Add 30g potassium silicate and 80g aluminum dihydrogen phosphate to 500g deionized water, stir evenly, then add 250g silica sol, 30g boehmite and 15g nano-cerium dioxide in turn, ultrasonically disperse for 30min, heat in a water bath at 25℃, and mature at 100rpm for 24h to obtain a sealing agent. Add the surface porous magnesium titanate ceramic stainless steel to the antibacterial impregnation solution, immerse at 60℃ and -0.09MPa negative pressure for 30min, dry at 80℃ for 1h, then heat to 650℃ under nitrogen protection and sinter for 45min. After sintering, cool to room temperature, apply the sealing agent, and the wet film thickness is 8μm. After coating, cure at 80℃ for 30min, 120℃ for 30min, and 750℃ for 20min to obtain high-temperature resistant stainless steel for oven.

[0084] Comparative Example 3: This comparative example relates to a method for preparing high-temperature resistant stainless steel for ovens. The difference from Example 1 is that only zinc nitrate solution and silver nitrate solution are impregnated, specifically:

[0085] Step 1: Add 0.1g polyacrylamide to 50mL deionized water, stir well, add 2g nano-cerium dioxide, and ultrasonically disperse for 20min to obtain a nano-cerium dioxide dispersion. Heat 800mL deionized water to 50°C, add 103g sodium molybdate, stir at 500rpm for 10min, then add 26g trisodium citrate. Continue stirring for 5min and then add the nano-cerium dioxide dispersion. After stirring well, adjust the pH to 8.5 and dilute to 1L to obtain a sodium molybdate electrolyte.

[0086] Step 2: The surface of XM-19 stainless steel was sandblasted. The sandblasting abrasive was nano-zirconium corundum. The sandblasting pressure was 0.6 MPa and the sandblasting time was 3 min. During sandblasting, the abrasive was 70° to the stainless steel surface. After sandblasting, it was transferred to the reaction chamber of the plasma equipment, and a mixture of argon, oxygen and hydrogen (volume ratio of 3:1:0.05) was introduced. The power supply was started for plasma treatment, the power supply power was set to 500 W, and the treatment time was 8 min. After the treatment was completed, the oxygen and hydrogen were turned off, the power supply power was adjusted to 200 W, and the treatment was continued for 2 min. It was then transferred as an anode to a sodium molybdate electrolyte, with an iron plate as the cathode, and treated at 40 ° C and a peak pulse voltage of 10 V for 8 min to obtain a pretreated stainless steel substrate;

[0087] Step 3: Place the pretreated stainless steel substrate into the reaction chamber of the magnetron sputtering equipment, seal the reaction chamber, preheat the substrate temperature to 400 °C, and evacuate to 5×10 -4Pa, introduce a mixture of nitrogen and argon, set the nitrogen flow rate to 20sccm, the argon flow rate to 60sccm, start the titanium-iron alloy target DC power supply, deposit a 0.8μm titanium-iron nitride layer, set the power supply power to 8KW, the bias voltage to -120V, and the deposition time to 27min, turn off the titanium-iron alloy target power supply, start the aluminum-titanium alloy target DC power supply and the titanium silicide target DC power supply, alternately deposit 0.5μm aluminum titanium nitride / nitrogen silicon titanium layer, set the aluminum-titanium alloy target power supply power to 6KW, the nitrogen flow rate to 30sccm, and the deposition time to 12s, the titanium silicide target power supply power to 4KW, the nitrogen flow rate to 60sccm, and the deposition time to 8s, and perform alternating deposition 16 times to obtain surface magnetron sputtering treated stainless steel;

[0088] Step 4: Add 241.5 g of aluminum chloride hexahydrate to 1 L of deionized water, stir evenly at 60° C., add 145 mL of ammonia water, and allow to stand in the dark at room temperature for 72 hours to obtain an aluminum sol. Add 200 g of ammonium bicarbonate to the aluminum sol, soak for 30 minutes, then take out and vacuum dry at 60° C. for 8 hours to obtain a pore-forming agent. Mix magnesium titanate and the pore-forming agent evenly at a mass ratio of 7:3 to obtain a ceramic coating powder.

[0089] Step 5: Place the surface magnetron sputtering treated stainless steel into a plasma spraying device. After preheating the substrate to 400°C, plasma spray the ceramic coating powder onto the surface magnetron sputtering treated stainless steel to form a 100 μm porous magnesium titanate ceramic layer. Set the power supply to 40 kW, the powder feeding rate to 35 g / min, and the spraying distance to 60 mm to obtain surface porous magnesium titanate ceramic stainless steel.

[0090] Step 6: Add 30g potassium silicate and 80g aluminum dihydrogen phosphate to 500g deionized water, stir evenly, then add 250g silica sol, 30g boehmite and 15g nano-cerium dioxide in turn, ultrasonically disperse for 30min, heat in a water bath at 25°C, and mature at 100rpm for 24h to obtain a sealing agent. The surface of the porous magnesium titanate ceramic stainless steel is coated with the sealing agent, and the wet film thickness is 8μm. After coating, cure at 80°C for 30min, 120°C for 30min, and 750°C for 20min to obtain high-temperature resistant stainless steel for oven.

[0091] Detection experiment:

[0092] According to each embodiment and comparative example, high-temperature resistant stainless steel samples for oven use were prepared and tested as follows.

[0093] Heavy metal migration test: The heavy metal migration test of high-temperature resistant stainless steel for ovens was conducted in accordance with the National Food Safety Standard for Metallic Materials for Food Contact (GB 4806.9-2023). An Agilent 7900 inductively coupled plasma mass spectrometer (Agilent) was used for the test. A 4wt% acetic acid solution was pre-filled into the migration test cell (material: PFTE) and heated to 70°C. The high-temperature resistant stainless steel sample was cut to a surface area / acetic acid solution volume = 6dm 2 / L, then put the cut sample into the migration test pool and soak it for 2 hours. After 2 hours, take out the sample, filter the liquid in the pool with a 0.45μm filter membrane, add concentrated nitric acid and mix evenly (the nitric acid after mixing is 1wt%), and finally use inductively coupled plasma mass spectrometry to measure the heavy metal concentration in the liquid to obtain the heavy metal migration amount.

[0094] High temperature resistance test: The test refers to the "Test method for oxidation resistance of steel" (GB / T 13303-1991). A 20mm×10mm×2mm oven-resistant high-temperature stainless steel sample is weighed and placed in a corundum crucible. The crucible is then placed in a high-temperature box-type resistance furnace and heated to 800°C. The crucible is heated in an air atmosphere for 500 hours. After 500 hours, the crucible is taken out and sealed, cooled to 100°C, and then placed in a desiccator to cool to room temperature. The crucible is taken out and weighed, and the oxidation weight gain is calculated.

[0095] Antibacterial test: The test refers to "Surface Antibacterial Stainless Steel Part 1: Electrochemical Method" (GB / T 24170.1-2023). Staphylococcus aureus and Escherichia coli are selected as test bacteria. After activation, the bacteria are cultured at 37℃ for 18 hours and diluted to 10 5 CFU / mL of bacterial suspension, a 50mm×50mm oven-resistant high-temperature stainless steel sample was sterilized by ultraviolet irradiation for 30 minutes and wiped with 75wt% ethanol. 0.1mL of bacterial suspension was evenly coated on the sample surface, and then covered with a 40μm thick polyethylene film. The sample was incubated at 35℃ and 90% humidity for 24 hours, and the number of colonies on the sample was detected. A 304 stainless steel sheet of the same size was used as a control to test the antibacterial rate of the sample.

[0096]

[0097] Conclusion: It can be seen from the test data that the oxidation weight gain of the high-temperature resistant stainless steel samples for ovens prepared by the method provided in the embodiment is less than that of the comparative example, and the samples have excellent antibacterial rates of Staphylococcus aureus and Escherichia coli, and the migration amounts of elements such as chromium, nickel, and copper are also extremely low. The high-temperature resistant stainless steel for ovens provided by the present invention has good high-temperature resistance and antibacterial properties, and the migration amount of metal elements also meets the requirements of food-grade stainless steel.

[0098] 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 preparing high-temperature resistant stainless steel for ovens, characterized by: Specifically: Step 1: After sandblasting, the stainless steel surface is plasma activated and passivated with sodium molybdate electrolyte to obtain a pretreated stainless steel substrate; Step 2: Using magnetron sputtering technology, a titanium iron nitride layer and an aluminum titanium nitride / nitrogen silicon titanium transition layer are sequentially deposited on the pretreated stainless steel substrate to obtain surface magnetron sputtering treated stainless steel; Step 3: plasma spraying ceramic coating powder on the surface of magnetron sputtering treated stainless steel to prepare surface porous magnesium titanate ceramic stainless steel; Step 4: adding the surface porous magnesium titanate ceramic stainless steel to the antibacterial impregnation solution, immersing at 60-70°C, (-0.08)-(-0.09) MPa negative pressure for 30-40 minutes, drying at 70-80°C for 1-2 hours, heating to 650-670°C under nitrogen protection and sintering for 30-45 minutes, cooling to room temperature after sintering, applying a sealing agent, and the wet film thickness is 8-10 μm. After coating, curing at 80-100°C for 20-30 minutes, curing at 120-140°C for 20-30 minutes, and curing at 750-770°C for 10-20 minutes to obtain high-temperature resistant stainless steel for oven use; In step 4, the preparation method of the antibacterial impregnation solution is: Add nano zinc oxide to polyvinyl pyrrolidone ethanol dispersion, ultrasonically disperse for 20-30 minutes, add ethyl orthosilicate, stir evenly, add ammonia water dropwise, react at 40-50 ° C for 5-6 hours, and vacuum dry at 60-70 ° C for 3-4 hours to obtain silicon dioxide coated zinc oxide, add silicon dioxide coated zinc oxide to silver nitrate aqueous solution, adsorb at (-0.08)-(-0.09) MPa negative pressure for 20-30 minutes, let it stand for 1.5-2 hours, add sodium borohydride solution dropwise, and The mixture was reacted at 25-30°C for 20-30 minutes. After the reaction was completed, the mixture was centrifuged, washed with deionized water, and vacuum-dried at 60-70°C for 4-6 hours to obtain silver-zinc antibacterial particles. The deionized water was preheated to 40-45°C, and the silver-zinc antibacterial particles were added. After ultrasonic dispersion for 20-30 minutes, silica sol, zinc molybdate, and nano-zirconium dioxide were added in sequence. The mixture was stirred at 800-1000 rpm for 30-45 minutes to form a suspension. The suspension was allowed to stand in a water bath at 40-45°C for 1-3 hours to obtain an antibacterial impregnation solution. In step 4, the preparation method of the sealing agent is: Potassium silicate and aluminum dihydrogen phosphate were added to deionized water, stirred evenly, and then silica sol, boehmite and nano-cerium dioxide were added in sequence. The mixture was ultrasonically dispersed for 20-30 minutes, heated in a water bath at 25-30°C, and aged at 100-200 rpm for 20-24 hours to obtain a sealing agent.

2. The method for preparing high-temperature resistant stainless steel for oven according to claim 1, characterized in that: In step 1, the preparation method of sodium molybdate electrolyte is: Add polyacrylamide to deionized water, stir evenly, then add nano-cerium dioxide, and ultrasonically disperse for 15-20 minutes to obtain a nano-cerium dioxide dispersion. Heat the deionized water to 50-60°C, add sodium molybdate, stir at 400-500 rpm for 10-15 minutes, then add trisodium citrate, continue stirring for 5-10 minutes, then add the nano-cerium dioxide dispersion, stir evenly, and adjust the pH to 8-9 to obtain a sodium molybdate electrolyte.

3. The method for preparing high-temperature resistant stainless steel for oven according to claim 2, characterized in that: Step 1 is as follows: The stainless steel surface is sandblasted, the sandblasting abrasive is nano-zirconium corundum, the sandblasting pressure is 0.5-0.6MPa, the sandblasting time is 3-5min, and after the sandblasting is completed, it is transferred to a plasma equipment reaction chamber, a mixed gas of argon, oxygen and hydrogen is introduced, and a power supply is started for plasma treatment, the power supply power is set to 500-550W, and the treatment time is 5-8min. After the treatment is completed, the oxygen and hydrogen are turned off, the power supply power is adjusted to 200-250W, and the treatment is continued for 1-2min. It is then transferred as an anode to a sodium molybdate electrolyte and treated at 40-45°C and 8-12V peak pulse voltage for 5-8min to obtain a pretreated stainless steel substrate.

4. The method for preparing high-temperature resistant stainless steel for oven according to claim 1, characterized in that: In step 2, when depositing the titanium iron nitride layer, the process parameters are: substrate temperature of 400-420°C, nitrogen flow rate of 20-30 sccm, argon flow rate of 60-70 sccm, power supply power of 7-8 kW, bias voltage of (-80)-(-120) V, deposition time of 25-35 min, and titanium iron nitride layer thickness of 0.8-1.0 μm; When depositing the aluminum titanium nitride / titanium silicon nitride layer, the process parameters are: the power of the aluminum titanium alloy target is 6-7KW, the nitrogen flow rate is 30-40sccm, the deposition time is 12-15s, the power of the titanium silicide target is 4-5KW, the nitrogen flow rate is 60-70sccm, the deposition time is 8-10s, and a total of 16-22 alternating depositions are performed. The thickness of the aluminum titanium nitride / titanium silicon nitride layer is 0.5-0.7μm.

5. The method for preparing high-temperature resistant stainless steel for oven according to claim 1, characterized in that: In step 3, the preparation method of ceramic coating powder is: Aluminum chloride hexahydrate is added to deionized water, stirred at 60-70°C, and then ammonia water is added. The mixture is allowed to stand in the dark at room temperature for 60-72 hours to obtain an aluminum sol. Ammonium bicarbonate is added to the aluminum sol, immersed for 20-30 minutes, and then taken out. The mixture is vacuum-dried at 60-70°C for 6-8 hours to obtain a pore-forming agent. Magnesium titanate and the pore-forming agent are evenly mixed to obtain a ceramic coating powder.

6. The method for preparing high-temperature resistant stainless steel for oven according to claim 5, characterized in that: Step 3 is as follows: The surface magnetron sputtering treated stainless steel is placed in a plasma spraying device. After the substrate is preheated to 400-420°C, the ceramic coating powder is plasma sprayed on the surface magnetron sputtering treated stainless steel to form an 80-100μm porous magnesium titanate ceramic layer. The power supply is set to 35-40KW, the powder feeding rate is 30-35g / min, and the spraying distance is 60-100mm to obtain the surface porous magnesium titanate ceramic stainless steel.

7. High-temperature resistant stainless steel for oven, prepared by the preparation method according to any one of claims 1 to 6.

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