Method for treating surface of pot body through rare earth modified salt bath ion permeation

Abstract

The invention discloses a method for treating the surface of a pot body through rare earth modified salt bath ion permeation. The method comprises the following steps that S1, an aluminum pot body is preheated; s2, the pot body is placed in a nitriding furnace containing first nitriding salt to be subjected to staged primary nitriding treatment, and a primary nitriding pot body with nitrides with the concentration gradient along the surface of the pot body is obtained; s3, the pot body is placed in an oxidation furnace containing oxidation salt to be subjected to oxidation treatment, and an oxidized pot body is obtained; s4, the pot body is placed in a nitriding furnace containing second nitriding salt to be subjected to secondary nitriding treatment, and a secondary nitriding pot body is obtained; and S5, cooling, washing with water, drying, and soaking in a sealing agent to obtain the pan body subjected to surface modification treatment. According to the method disclosed by the invention, the hardness, wear resistance and corrosion resistance of the surface of the pot body are remarkably improved, good non-stick performance and oxidation resistance are kept, and various cooking requirements in families and commercial kitchens can be met.

Description

Technical Field

[0001] The invention relates to the technical field of surface treatment of kitchen pots, and in particular to a method for treating the surface of a pot body by ion penetration using a rare earth modified salt bath. Background Art

[0002] During the use of kitchen pots and pans, the performance of the pot surface has a crucial impact on the cooking effect and service life. Traditional non-stick pan surface treatment methods mainly rely on coating technology, such as polytetrafluoroethylene (PTFE) coating. Although these coatings can provide certain non-stick properties, during long-term use, the coatings are prone to gradual wear and fall off due to high temperature, frequent friction and chemical corrosion, resulting in a decrease in non-stick performance. In addition, the hardness and wear resistance of traditional coatings are insufficient to meet the needs of high-intensity cooking. Especially in high-temperature environments, the coatings have poor stability and are prone to cracking or peeling. At the same time, the corrosion resistance of traditional coatings needs to be improved. They are easily corroded by chemicals such as acids and alkalis, affecting the overall performance and service life of the pot. Therefore, developing a surface treatment method that can significantly improve the hardness, wear resistance, corrosion resistance and antioxidant properties of the pot surface has become an important research direction in the current field of kitchen pot manufacturing. Summary of the Invention

[0003] In view of the above shortcomings of the existing technology, the present invention provides a method for treating the surface of a pan body by rare earth modified salt bath ion diffusion to solve the technical problems existing in traditional non-stick pan surface treatment methods, such as insufficient hardness, poor wear resistance, weak corrosion resistance, and easy degradation of non-stick performance.

[0004] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0005] A method for treating the surface of a pot body by ion-diffusion treatment with a rare earth modified salt bath, the method comprising the following steps:

[0006] S1: Place the aluminum pot in a preheating furnace and preheat to 400-450°C;

[0007] S2: The pot body, preheated in step S1, is placed in a nitriding furnace containing a first nitride salt for a phased primary nitriding treatment, resulting in a primary nitrided pot body with a nitride concentration gradient along the pot body surface. The present invention's phased nitriding treatment first immerses the inner surface of the pot bottom, then immerses the entire pot body. This unique method provides a more complete and uniform nitride distribution on the pot bottom, while also achieving a gradient distribution of concentrations that gradually changes from the inside out across the entire pot inner surface. The pot bottom, as the primary heating and food contact area, significantly improves its surface hardness and wear resistance after strengthening, effectively resisting frequent high-temperature cooking and food friction. Furthermore, this concentration gradient distribution on the inner surface of the pot further enhances the overall surface performance of the pot body, improving its overall service life and performance. The gradient nitride layer not only avoids stress concentration caused by sudden changes in hardness but also provides a more suitable transition interface for the subsequent adhesion of the oxide layer, making the oxide layer more firmly bonded to the pot surface and effectively improving the pot's corrosion resistance and antioxidant properties. This design not only optimizes the performance of the pot bottom, but also improves the overall performance of the entire pot surface, creating favorable conditions for subsequent further modifications and extending the service life of the pot body.

[0008] S3: The primary nitrided pot obtained in step S2 is placed in an oxidation furnace containing an oxidizing salt for oxidation treatment to obtain an oxidized pot. The oxidation furnace temperature is set at 350-400°C. Under the influence of the specific temperature and oxidizing salt, the oxidation treatment of the present invention causes the nitride layer on the pot surface to react with the components of the oxidizing salt to form a dense oxide film. This oxide film effectively blocks the intrusion of external corrosive media, improving the pot's corrosion resistance during use. It also prevents the pot from excessively oxidizing in high-temperature cooking environments, thereby extending the pot's service life.

[0009] S4: placing the oxidized pot body obtained in step S3 in a nitriding furnace containing a second nitriding salt for secondary nitriding treatment to obtain a secondary nitrided pot body;

[0010] S5: Cooling the secondary nitrided pot body obtained in step S4, washing it with water, drying it, and soaking it in a sealing agent to obtain a pot body after surface modification treatment.

[0011] As a preferred technical solution, the first nitride salt is composed of the following raw materials in parts by weight: 35 to 55 parts of urea, 10 to 15 parts of alkali metal carbonate, 1 to 5 parts of rare earth salt, 10 to 15 parts of cerium ammonium nitrate, 20 to 25 parts of sodium chloride and 1.5 to 5.5 parts of sodium borate. In the formula of the first nitride salt of the present invention, urea, as the main nitrogen source, decomposes at high temperature to produce cyanate ions. These cyanate ions are key active species in the formation of nitrides and can react with metal atoms on the surface of the pot body to form a hard nitride layer, thereby significantly enhancing the hardness and wear resistance of the pot body surface. Alkali metal carbonates (such as lithium carbonate, sodium carbonate, potassium carbonate) not only play a role in regulating pH value and promoting ion penetration, but also participate in the reaction as a carbon source, which helps to form a carbide-nitride complex structure, further improving the stability and performance of the nitride layer. At the same time, alkali metal carbonates maintain an alkaline environment in the salt bath, helping to stabilize the cyanate ion's presence, preventing premature decomposition or adverse reactions with other components, thereby maintaining a consistent cyanate ion concentration. The addition of rare earth salts (such as lanthanum chloride and yttrium chloride) refines the grain size, improving the toughness and fatigue resistance of the nitride layer while also enhancing corrosion resistance. The rare earth elements in these salts have a unique electronic structure, allowing them to form stable compounds with nitrides, further enhancing the hardness and wear resistance of the nitride layer. Cerium ammonium nitrate not only acts as a catalyst to accelerate the nitriding reaction and improve process efficiency, but also serves as a supplemental nitrogen source to further promote nitriding layer formation. The cerium oxide produced by its decomposition stabilizes the chemical environment of the salt bath, further promoting the formation and stabilization of cyanate ions. Furthermore, the active cerium element adsorbs and activates cyanate ions, increasing their reactivity and accelerating the nitriding reaction. Furthermore, cerium itself possesses excellent antioxidant and corrosion resistance, further enhancing the durability of the nitride layer. Sodium chloride, as an electrolyte salt, ensures uniform ion distribution and penetration into the pot surface. Sodium borate stabilizes the salt bath system, preventing other components from decomposing or volatilizing at high temperatures. This prevents fluctuations in cyanate ion concentration caused by compositional changes, ensuring the stability and consistency of the treatment process. By rationally controlling the ratio of each component and reaction conditions, the synergistic effect of this formula effectively improves the utilization efficiency of cyanate, reduces its residue in the salt bath, and minimizes potential environmental impact, achieving a highly efficient and environmentally friendly surface treatment.

[0012] As a preferred technical solution, the oxidizing salt is composed of the following raw materials in parts by weight: 30-40 parts sodium hydroxide, 15-25 parts potassium nitrate, 5-10 parts sodium chloride, 3-8 parts aluminum chloride, and 5-15 parts zinc chloride. In the oxidizing salt formula of the present invention, sodium hydroxide, as the primary alkaline component, provides a highly alkaline environment, promoting the oxidation reaction on the pot surface and forming a dense oxide film. Potassium nitrate acts as a co-oxidant during the oxidation process, accelerating the oxidation reaction and improving oxidation efficiency while also enhancing the uniformity and density of the oxide film. Sodium chloride, as an electrolyte salt, ensures that the oxidation reaction proceeds uniformly across the pot surface. During the oxidation process, aluminum chloride and zinc chloride react with the nitride layer on the pot surface to form a composite oxide layer, further enhancing the corrosion resistance and wear resistance of the oxide film. Aluminum chloride also improves the adhesion of the oxide film, while zinc chloride enhances the oxidation resistance of the oxide film. The synergistic effect of this formula forms a uniform, dense oxide film with excellent corrosion resistance and wear resistance on the surface of the pot, significantly improving the service life and performance of the pot.

[0013] As a preferred technical solution, the second nitriding salt is composed of the following raw materials in parts by weight: 35-55 parts urea, 5-15 parts alkali metal carbonate, 2-7 parts rare earth salt, 4-8 parts zirconium nitrate, 6-12 parts cerium ammonium nitrate, 20-25 parts sodium chloride, and 2.5-5.5 parts sodium silicate. The zirconium nitrate added to the second nitriding salt of the present invention decomposes at high temperatures to form zirconium oxides. These oxides can form a composite structure with the nitriding layer, further enhancing the hardness and wear resistance of the nitriding layer. Zirconium oxide also has excellent thermal and chemical stability, significantly improving the oxidation resistance and corrosion resistance of the nitriding layer. Furthermore, the nanoparticles formed by the zirconium oxide at high temperatures can fill the micropores of the nitriding layer, improving its density and enhancing the non-stick properties of the pot surface. Sodium silicate forms a silicate glass phase at high temperatures, which can fill the micropores of the nitriding layer, improving its density and smoothness. This glass phase forms a uniform protective film, significantly enhancing the non-stick and anti-fouling properties of the pot surface. At the same time, sodium silicate can also stabilize the salt bath system, preventing other components from decomposing or volatilizing at high temperatures, and ensuring the stability and consistency of the treatment process.

[0014] As a preferred technical solution, the staged one-time nitriding treatment includes immersing the inner surface of the pot bottom in the first nitride salt raw material in the first stage, and immersing the entire inner surface of the pot body including the pot bottom and pot wall in the first nitride salt raw material in the second stage.

[0015] As a preferred technical solution, the alkali metal carbonate is at least one of lithium carbonate, sodium carbonate, and potassium carbonate.

[0016] As a preferred technical solution, the rare earth salt is at least one of lanthanum chloride, yttrium chloride, lanthanum nitrate, and yttrium nitrate.

[0017] As a preferred technical solution, in step S3, oxygen is also introduced into the oxidation furnace for oxidation treatment.

[0018] As a preferred technical solution, the operating temperature of the nitriding furnace is 600-650°C.

[0019] As a preferred technical solution, the sealing agent is composed of the following raw materials in parts by weight: 30 to 50 parts of silane impregnation solution, 20 to 30 parts of polytetrafluoroethylene powder, 5 to 15 parts of nano titanium dioxide, 5 to 15 parts of zinc stearate, 3 to 10 parts of Film-forming aid and 15 to 35 parts of deionized water.

[0020] Beneficial effects of the present invention:

[0021] The present invention's rare earth-modified salt bath ion-dip ionization treatment method for the pot surface, by innovatively adding rare earth elements and other specific components to nitride and oxidation salts, not only significantly improves the pot surface's hardness and wear resistance, but also significantly enhances its corrosion and oxidation resistance. This design not only enhances the pot surface's overall performance while maintaining a good non-stick effect, helping to extend the pot's lifespan and improve its stability in high-temperature cooking environments.

[0022] In general, the surface of the non-stick pan body after the rare earth modified salt bath ion diffusion treatment of the present invention not only has excellent hardness, wear resistance and corrosion resistance, but also maintains good non-stick performance and antioxidant properties, which can meet various cooking needs in home and commercial kitchens and has broad application prospects. DETAILED DESCRIPTION

[0023] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are merely examples, and those skilled in the art may conceive of other obvious variations.

[0024] Example 1

[0025] The method of treating the surface of a pot body by ion-diffusion using a rare earth modified salt bath in this embodiment comprises the following steps:

[0026] S1: Place the aluminum pot in a preheating furnace and preheat to 450℃ for 30 minutes to ensure uniform temperature of the pot.

[0027] S2: The pot body preheated in step S1 is placed in a nitriding furnace containing a first nitriding salt for a phased primary nitriding treatment to obtain a primary nitrided pot body with a concentration gradient of nitride along the surface of the pot body; the phased primary nitriding treatment includes the following steps: first, immersing the inner surface of the pot bottom in the first nitriding salt raw material for 2 hours; and second, immersing the entire inner surface of the pot body including the pot bottom and pot wall in the first nitriding salt raw material for 1 hour. The operating temperature of the nitriding furnace is 630°C. The first nitriding salt is composed of the following raw materials in parts by weight: 45 parts of urea, 12 parts of alkali metal carbonate (composed of 4 parts of lithium carbonate, 6 parts of sodium carbonate and 2 parts of potassium carbonate), 3 parts of lanthanum chloride, 12 parts of ammonium cerium nitrate, 22 parts of sodium chloride and 3 parts of sodium borate. Each raw material must be dried before mixing to ensure that there is no residual moisture, and must be fully stirred during mixing to ensure the uniformity of the salt bath.

[0028] S3: The primary nitrided pot body obtained in step S2 is placed in an oxidation furnace containing an oxidizing salt for oxidation treatment to obtain an oxidized pot body; the oxidation furnace temperature is set to 360°C, the treatment time is 1.5 hours, and the furnace atmosphere is nitrogen containing 25% oxygen. The oxidizing salt is composed of the following raw materials in parts by weight: 35 parts sodium hydroxide, 20 parts potassium nitrate, 8 parts sodium chloride, 5 parts aluminum chloride, and 10 parts zinc chloride. Before use, the oxidizing salt must be dried at 120°C for 2 hours to remove moisture and ensure the smooth progress of the oxidation reaction. During the oxidation process, the oxygen concentration in the furnace atmosphere must be regularly checked to ensure that it is stable within the set range.

[0029] S4: The oxidized pot body obtained in step S3 is placed in a nitriding furnace containing a second nitriding salt for secondary nitriding treatment to obtain a secondary nitrided pot body; the nitriding furnace is operated at a temperature of 640°C and the treatment time is 2 hours. The second nitriding salt is composed of the following raw materials in parts by weight: 50 parts urea, 10 parts alkali metal carbonate (composed of 3 parts lithium carbonate, 5 parts sodium carbonate, and 2 parts potassium carbonate), 5 parts yttrium chloride, 6 parts zirconium nitrate, 10 parts ammonium cerium nitrate, 23 parts sodium chloride, and 4 parts sodium silicate.

[0030] S5: After the secondary nitrided pot body obtained in step S4 is cooled to room temperature, it is washed with water, dried, and dipped in a sealant to obtain a pot body after surface modification. Deionized water should be used for washing, the water temperature should be controlled at 50°C, and the washing time should be 10 minutes to completely remove the salt remaining on the surface. Hot air drying is used for drying, the temperature is 80°C, and the time is 20 minutes. The sealant is composed of the following raw materials in parts by weight: 40 parts of silane impregnation solution (aminosilane impregnation solution with model number KH-551), 25 parts of polytetrafluoroethylene micropowder, 10 parts of nano titanium dioxide, 10 parts of zinc stearate, 5 parts of film-forming aid (organic silicone film-forming aid with model number BYK-348) and 20 parts of deionized water. The sealant needs to be stirred evenly before use, and the dipping time is 15 minutes to ensure uniform coverage of the pot surface. After dipping, it needs to be cured at 120°C for 30 minutes to form a uniform protective film.

[0031] Example 2

[0032] The method of treating the surface of a pot body by ion-diffusion using a rare earth modified salt bath in this embodiment comprises the following steps:

[0033] S1: Place the aluminum pot in a preheating furnace and preheat to 450℃ for 30 minutes to ensure uniform temperature of the pot.

[0034] S2: The pot body preheated in step S1 is placed in a nitriding furnace containing a first nitriding salt for a phased primary nitriding treatment to obtain a primary nitrided pot body with a concentration gradient of nitride along the surface of the pot body; the phased primary nitriding treatment includes the following steps: first, immersing the inner surface of the pot bottom in the first nitriding salt raw material for 2 hours; and second, immersing the entire inner surface of the pot body including the pot bottom and pot wall in the first nitriding salt raw material for 1 hour. The operating temperature of the nitriding furnace is 630°C. The first nitriding salt is composed of the following raw materials in parts by weight: 50 parts of urea, 10 parts of alkali metal carbonate (composed of 3 parts of lithium carbonate, 5 parts of sodium carbonate and 2 parts of potassium carbonate), 4 parts of yttrium chloride, 10 parts of ammonium cerium nitrate, 20 parts of sodium chloride and 4 parts of sodium borate. Each raw material must be dried before mixing to ensure that there is no residual moisture, and must be fully stirred during mixing to ensure the uniformity of the salt bath.

[0035] S3: The primary nitrided pot body obtained in step S2 is placed in an oxidation furnace containing an oxidizing salt for oxidation treatment to obtain an oxidized pot body; the oxidation furnace temperature is set to 400°C, the treatment time is 1.5 hours, and the furnace atmosphere is nitrogen containing 25% oxygen. The oxidizing salt is composed of the following raw materials in parts by weight: 30 parts sodium hydroxide, 15 parts potassium nitrate, 10 parts sodium chloride, 4 parts aluminum chloride, and 8 parts zinc chloride. Before use, the oxidizing salt must be dried at 120°C for 2 hours to remove moisture and ensure the smooth progress of the oxidation reaction. During the oxidation process, the oxygen concentration in the furnace atmosphere must be regularly checked to ensure that it is stable within the set range.

[0036] S4: Placing the oxidized pot body obtained in step S3 in a nitriding furnace containing a second nitriding salt for secondary nitriding treatment to obtain a secondary nitrided pot body; the nitriding furnace is operated at a temperature of 650°C and the treatment time is 2 hours. The second nitriding salt is composed of the following raw materials in parts by weight: 35 parts urea, 15 parts alkali metal carbonate (composed of 5 parts lithium carbonate, 7 parts sodium carbonate, and 3 parts potassium carbonate), 6 parts lanthanum chloride, 8 parts zirconium nitrate, 12 parts ammonium cerium nitrate, 25 parts sodium chloride, and 5.5 parts sodium silicate.

[0037] S5: The secondary nitrided pot body obtained in step S4 is cooled to room temperature, washed with water, dried, and dipped in a sealing agent to obtain a pot body after surface modification. Deionized water should be used for washing, the water temperature should be controlled at 50°C, and the washing time should be 10 minutes to completely remove the salt remaining on the surface. Hot air drying is used for drying, the temperature is 80°C, and the time is 20 minutes. The sealing agent is the same as that in Example 1. The sealing agent needs to be stirred evenly before use, and the dipping time is 15 minutes to ensure that the surface of the pot body is evenly covered. After dipping, it needs to be cured at 120°C for 30 minutes to form a uniform protective film.

[0038] Example 3

[0039] The method of treating the surface of a pot body by ion-diffusion using a rare earth modified salt bath in this embodiment comprises the following steps:

[0040] S1: Place the aluminum pot in a preheating furnace and preheat to 450℃ for 30 minutes to ensure uniform temperature of the pot.

[0041] S2: The pot body preheated in step S1 is placed in a nitriding furnace containing a first nitriding salt for a phased primary nitriding treatment to obtain a primary nitrided pot body with a concentration gradient of nitride along the surface of the pot body; the phased primary nitriding treatment includes the following steps: first, immersing the inner surface of the pot bottom in the first nitriding salt raw material for 2 hours; and second, immersing the entire inner surface of the pot body including the pot bottom and pot wall in the first nitriding salt raw material for 1 hour. The operating temperature of the nitriding furnace is 600°C. The first nitriding salt is composed of the following raw materials in parts by weight: 35 parts of urea, 15 parts of alkali metal carbonate (composed of 5 parts of lithium carbonate, 5 parts of sodium carbonate and 5 parts of potassium carbonate), 5 parts of lanthanum chloride, 15 parts of ammonium cerium nitrate, 25 parts of sodium chloride and 5.5 parts of sodium borate. Each raw material must be dried before mixing to ensure that there is no residual moisture, and must be fully stirred during mixing to ensure the uniformity of the salt bath.

[0042] S3: The primary nitrided pot body obtained in step S2 is placed in an oxidation furnace containing an oxidizing salt for oxidation treatment to obtain an oxidized pot body; the oxidation furnace temperature is set to 380°C, the treatment time is 1.5 hours, and the furnace atmosphere is nitrogen containing 25% oxygen. The oxidizing salt is composed of the following raw materials in parts by weight: 40 parts sodium hydroxide, 25 parts potassium nitrate, 10 parts sodium chloride, 6 parts aluminum chloride, and 15 parts zinc chloride. Before use, the oxidizing salt must be dried at 120°C for 2 hours to remove moisture and ensure the smooth progress of the oxidation reaction. During the oxidation process, the oxygen concentration of the furnace atmosphere must be regularly checked to ensure that it is stable within the set range.

[0043] S4: The oxidized pot body obtained in step S3 is placed in a nitriding furnace containing a second nitriding salt for secondary nitriding treatment to obtain a secondary nitrided pot body; the nitriding furnace is operated at a temperature of 620°C and the treatment time is 2 hours. The second nitriding salt is composed of the following raw materials in parts by weight: 55 parts urea, 15 parts alkali metal carbonate (composed of 5 parts lithium carbonate, 5 parts sodium carbonate, and 5 parts potassium carbonate), 7 parts lanthanum chloride, 8 parts zirconium nitrate, 12 parts ammonium cerium nitrate, 20 parts sodium chloride, and 3.5 parts sodium silicate.

[0044] S5: The secondary nitrided pot body obtained in step S4 is cooled to room temperature, washed with water, dried, and dipped in a sealing agent to obtain a pot body after surface modification. Deionized water should be used for washing, the water temperature should be controlled at 50°C, and the washing time should be 10 minutes to completely remove the salt remaining on the surface. Hot air drying is used for drying, the temperature is 80°C, and the time is 20 minutes. The sealing agent is the same as that in Example 1. The sealing agent needs to be stirred evenly before use, and the dipping time is 15 minutes to ensure that the surface of the pot body is evenly covered. After dipping, it needs to be cured at 120°C for 30 minutes to form a uniform protective film.

[0045] The pot bodies obtained after treatment by the methods of Examples 1 to 3 were subjected to performance tests, and the performance results are shown in Table 1:

[0046] Among them, hardness test: the test index is surface hardness. According to the ASTM E384 standard, a microhardness tester is used to test the hardness of the treated pot surface. The sample is cut into specimens of appropriate size to ensure that the test surface is flat and free of contamination. The specimen is placed on the test platform of the microhardness tester, and a load of 100g and a loading time of 10 seconds are selected for testing. Each specimen is tested at 5 different positions, the hardness value is recorded and the average value is calculated. The test results are expressed in HV (Vickers hardness) and are used to evaluate the hardness level of the pot surface.

[0047] Wear resistance test: Conducted in accordance with ISO 12947. The treated pot surface is tested using a wear tester. The pot is fixed to the tester fixture, 180-grit SiC sandpaper is used as the abrasive, and the load is 500g. The wear stroke is set to 1000 round trips, with each stroke length of 100mm and a speed of 60 times / minute. After the test is completed, the surface wear is observed under a microscope, the wear depth or width is measured, and the wear rate is calculated. The wear resistance test results are expressed as a wear rate and are used to evaluate the wear resistance of the pot surface.

[0048] Corrosion resistance testing: Conducted in accordance with ASTM B117. The treated pot samples were placed in a salt spray test chamber set at 35°C. The salt spray solution consisted of a 5% sodium chloride solution with a pH between 6.5 and 7.2. The spray cycle was continuous, and the test lasted for 96 hours. After the test, the samples were removed, rinsed with deionized water, and dried. Surface corrosion was then observed.

[0049] Impact resistance testing: Conducted in accordance with GB / T 229. The treated pot surface is tested using a pendulum impact tester. The pot sample is cut into standard specimens measuring 10mm x 10mm x 50mm, ensuring a flat and defect-free surface. The specimen is secured in the tester fixture and subjected to an impact energy of 5J and an impact velocity of 5m / s. The presence of breakage or cracks is recorded. The impact resistance test results, expressed as the presence of breakage or cracks, are used to assess the pot surface's impact resistance.

[0050] Oxidation resistance testing: Conducted in accordance with GB / T 6461. Treated pot samples were placed in a high-temperature oxidation test chamber set at 250°C for 24 hours. After the test, the samples were removed, rinsed with deionized water, and dried. The surface oxidation was then observed. The results, expressed as the thickness of the oxide layer, were used to assess the pot surface's resistance to oxidation. Table 1 project Example 1 Example 2 Example 3 Hardness (HV) 750 780 760 Wear resistance, % 0.05 0.05 0.06 Corrosion resistance No obvious rust spots No obvious rust spots No obvious rust spots Impact resistance No cracks No cracks No cracks Antioxidant properties, μm 7 6 8

[0051] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. Various changes and improvements are possible without departing from the spirit and scope of the present invention, and such changes and improvements fall within the scope of the invention as claimed.

Claims

1. A method for treating the surface of a pot body by ion diffusion with a rare earth modified salt bath, characterized in that: The method comprises the following steps: S1: Place the aluminum pot in a preheating furnace and preheat to 400-450°C; S2: placing the pot body preheated in step S1 in a nitriding furnace containing a first nitriding salt for a phased primary nitriding treatment to obtain a primary nitrided pot body having a nitride concentration gradient along the surface of the pot body; S3: placing the primary nitrided pot body obtained in step S2 in an oxidation furnace filled with oxidizing salt for oxidation treatment to obtain an oxidized pot body; setting the temperature of the oxidation furnace to 350-400° C.; S4: placing the oxidized pot body obtained in step S3 in a nitriding furnace containing a second nitriding salt for secondary nitriding treatment to obtain a secondary nitrided pot body; S5: Cooling the secondary nitrided pot body obtained in step S4, washing it with water, drying it, and soaking it in a sealing agent to obtain a pot body after surface modification treatment.

2. The method for treating the surface of a pot body by ion diffusion with a rare earth modified salt bath according to claim 1, characterized in that: The first nitride salt is composed of the following raw materials in parts by weight: 35-55 parts of urea, 10-15 parts of alkali metal carbonate, 1-5 parts of rare earth salt, 10-15 parts of cerium ammonium nitrate, 20-25 parts of sodium chloride and 1.5-5.5 parts of sodium borate.

3. The method for treating the surface of a pot body by ion diffusion with a rare earth modified salt bath according to claim 1, characterized in that: The oxidizing salt is composed of the following raw materials in parts by weight: 30-40 parts of sodium hydroxide, 15-25 parts of potassium nitrate, 5-10 parts of sodium chloride, 3-8 parts of aluminum chloride and 5-15 parts of zinc chloride.

4. The method for treating the surface of a pot body by ion diffusion with a rare earth modified salt bath according to claim 1, wherein: The second nitride salt is composed of the following raw materials in parts by weight: 35-55 parts of urea, 5-15 parts of alkali metal carbonate, 2-7 parts of rare earth salt, 4-8 parts of zirconium nitrate, 6-12 parts of cerium ammonium nitrate, 20-25 parts of sodium chloride and 2.5-5.5 parts of sodium silicate.

5. The method for treating the surface of a pot body by ion diffusion with a rare earth modified salt bath according to claim 1, characterized in that: The staged one-step nitriding treatment includes immersing the inner surface of the pot bottom in a first nitride salt raw material in a first stage, and immersing the entire inner surface of the pot body including the pot bottom and pot wall in the first nitride salt raw material in a second stage.

6. The method for treating the surface of a pot body by ion diffusion with a rare earth modified salt bath as claimed in claim 2 or 4, characterized in that: The alkali metal carbonate is at least one of lithium carbonate, sodium carbonate and potassium carbonate.

7. The method for treating the surface of a pot body by ion-diffusion treatment with a rare earth modified salt bath according to claim 2 or 4, characterized in that: The rare earth salt is at least one of lanthanum chloride, yttrium chloride, lanthanum nitrate and yttrium nitrate.

8. The method for treating the surface of a pot body by ion diffusion with a rare earth modified salt bath as claimed in claim 1, characterized in that: In step S3, oxygen is introduced into the oxidation furnace for oxidation treatment.

9. The method for treating the surface of a pot body by ion diffusion with a rare earth modified salt bath as claimed in claim 2 or 4, characterized in that: The operating temperature of the nitriding furnace is 600-650°C.

10. The method for treating the surface of a pot body by ion diffusion with a rare earth modified salt bath as claimed in claim 1, characterized in that: The sealing agent is composed of the following raw materials in parts by weight: 30-50 parts of silane impregnation solution, 20-30 parts of polytetrafluoroethylene powder, 5-15 parts of nano titanium dioxide, 5-15 parts of zinc stearate, 3-10 parts of film-forming aid and 15-35 parts of deionized water.