Preparation method of high-temperature-resistant anti-oxidation coating for stainless steel

Abstract

The invention discloses a preparation method of a high-temperature-resistant anti-oxidation coating for stainless steel, which comprises the following steps: step 1, weighing raw materials according to a mass ratio of alumina ceramic powder to titanium oxide ceramic powder to silicon oxide ceramic powder of 1: (0.5-2): (0.5-4); 2, the weighed ceramic powder is put into a ball mill for ball milling, and ceramic powder is obtained; step 3, putting the ball-milled ceramic powder into a drying oven for drying; step 4, adding dry sodium silicate into the dried ceramic powder, putting the ceramic powder and the sodium silicate into a container to form mixed powder, adding deionized water into the container, and uniformly stirring to form white ceramic slurry; 5, the surface of the stainless steel is coated with the prepared ceramic slurry, and the stainless steel is put into a drying oven to be dried; and 6, the dried coating is placed in a high-temperature furnace to be sintered, furnace cooling is carried out after sintering is completed, and the high-temperature-resistant coating is formed. According to the technical scheme, the high-temperature-resistant and corrosion-resistant performance of the coating for the stainless steel can be remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of stainless steel coatings, and in particular to a method for preparing a high-temperature resistant and anti-oxidation coating for stainless steel. Background Art

[0002] Stainless steel boasts excellent corrosion resistance, weldability, and mechanical properties, making it widely used in household appliances, medical devices, and industrial piping. For example, 304 stainless steel, with its excellent room-temperature corrosion resistance and low raw material costs, is widely used in the metallurgical, atomic, and aerospace industries. Stainless steel forms a passive layer on its surface, protecting the underlying material from corrosion. However, as the temperature rises, this passive layer is destroyed, and the rate of oxidative corrosion of the underlying material increases exponentially. Stainless steel can typically be used for extended periods within 200°C. However, above 200°C, the passive layer is destroyed, transitioning from a passive state to an active state, and the underlying material begins to oxidize and corrode. Therefore, applying an oxide coating to the surface of stainless steel can significantly improve its high-temperature oxidation resistance and extend the service life of stainless steel products. In the petrochemical industry, stainless steel piping and reactors, among other equipment, must not only withstand high temperatures but also withstand corrosion from chemical media. High-temperature corrosion-resistant coatings require stainless steel materials to be used in high-temperature environments for extended periods, and an oxidation-resistant ceramic coating is applied to the exterior of the stainless steel. The coating has the following characteristics: 1) High-temperature stability. Within the service temperature range of stainless steel materials, the coating material has high thermal stability and does not undergo phase change or other rapid volume expansion or contraction; 2) Chemical inertness. The coating material requires high chemical stability during long-term service at high temperatures and does not react with oxygen, nitrogen and carbon dioxide in the air; 3) Density. The coating is dense at high temperatures, effectively preventing oxygen atoms from penetrating the coating and reacting with the substrate material for oxidation; 4) Good thermal expansion matching. The coating material is required to have a similar thermal expansion coefficient to that of stainless steel. Otherwise, during the heating / cooling process, high residual stress (interface thermal stress) will be generated due to the different thermal expansion / contraction coefficients, causing the coating to fall off; 5) Economical. A coating material that can be used for large-scale industrial applications needs to be low-cost, easy to construct, and the construction operation does not rely on large and complex equipment in order to achieve commercialization.

[0003] Existing stainless steel high-temperature oxidation resistant coating technology is difficult to meet the above five requirements at the same time, especially in terms of raw materials and processing costs. Patent CN202011289482.9 uses high-cost metal materials such as NiCoCrAlY as raw materials, and adopts laser cladding equipment to form a high-temperature resistant and oxidation-resistant coating on the surface of stainless steel. Although this technology is effective, the additive manufacturing processing cost is high. Patent CN201810836444.7 uses a variety of oxides as raw materials to prepare antioxidant coatings. The use of expensive Co2O3 and La2O3 significantly increases the production cost. The coating material needs to be sintered and crushed at 1300-1450 degrees Celsius, and then coated on the stainless steel surface. The steps are relatively cumbersome. In order to increase the bonding strength between the corrosion-resistant coating and the substrate, patent CN201110137514.8 adds a FeCrAlY intermediate layer between the substrate and the coating, and finally a mixture coating of SiC, TiC, TiO2 and Fe is coated on the surface. The preparation of the intermediate layer makes the preparation more complicated, and uses relatively expensive Y and TiC materials, which is not suitable for low-cost industrial application scenarios. Summary of the Invention

[0004] The main purpose of the present invention is to propose a method for preparing a high-temperature resistant and anti-oxidation coating for stainless steel, aiming to solve the problem of long-term use of stainless steel in a high-temperature corrosive environment and provide a method for preparing a high-temperature resistant and anti-corrosion coating.

[0005] To achieve the above object, the present invention provides a method for preparing a high-temperature resistant and anti-oxidation coating for stainless steel, comprising the following steps:

[0006] Step 1: weigh the raw materials according to the mass ratio of alumina ceramic powder: titanium oxide ceramic powder: silicon oxide ceramic powder is 1: (0.5-2): (0.5-4);

[0007] Step 2: Put the weighed ceramic powder into a ball mill and grind it to obtain ceramic powder;

[0008] Step 3: Place the ball-milled ceramic powder into an oven for drying;

[0009] Step 4: Add dried sodium silicate to the dried ceramic powder, place the ceramic powder and sodium silicate in a container to form a mixed powder, add deionized water to the container, and stir evenly to form a white ceramic slurry;

[0010] Step 5: Apply the prepared ceramic slurry to the stainless steel surface and place it in an oven for drying;

[0011] Step six: Place the dried coating into a high-temperature furnace for sintering, and cool it down with the furnace after sintering to form a high-temperature resistant coating.

[0012] Optionally, in step 2, the ball mill is a planetary ball mill, the ball-to-material ratio is 3:1, the ball milling medium is deionized water, the rotation speed is 300 rpm, and the ball milling mixing is performed for 2 hours.

[0013] Optionally, the grinding balls in step 2 are alumina balls, the diameter of the largest grinding ball in the ball mill is not greater than 8 mm, and the diameter of the smallest grinding ball is not less than 3 mm.

[0014] Optionally, in step three, the baking temperature in the oven is 120 degrees Celsius.

[0015] Optionally, in step 4, the ceramic powder and sodium silicate are weighed in a mass ratio of 1:8, and the weighed ceramic powder and sodium silicate are placed in a container, and the amount of deionized water added is 30% of the mixed powder.

[0016] Optionally, the mixed powder is heated while being stirred in step 4, and the heating temperature is 80 degrees Celsius.

[0017] Optionally, in step five, the oven temperature is 150 degrees Celsius, the baking time is 20 minutes, and the thickness of the coating is 20-30 microns.

[0018] Optionally, in step six, the sintering temperature is not less than 900 degrees Celsius, and the sintering is performed for 2 hours followed by cooling in the furnace.

[0019] Optionally, before step five, the stainless steel surface is first cleaned with a 10% NaOH solution and then rinsed with deionized water.

[0020] The beneficial effects of the present invention are:

[0021] 1. The present invention uses low-cost aluminum oxide, titanium oxide and silicon oxide ceramic powders as main raw materials, and adopts sodium silicate as inorganic binder, which can ensure the economy of raw materials and the good processability of coating. The biggest problem of preparing inorganic coating on metal surface is that the thermal expansion coefficients of the two do not match. During the cooling process, the inorganic coating is easy to break. The ceramic raw materials used in the present invention can form a ceramic solid solution with the passivation layer on the stainless steel surface, thus solving the problem of inorganic coating falling off and peeling on the metal surface. The inorganic coating and the passivation layer on the stainless steel surface complement each other, ensuring the anti-oxidation and corrosion-resistant properties of stainless steel in high-temperature environments.

[0022] 2. Compared with traditional laser cladding technology, the present invention has low technical cost, a wide range of raw materials and low cost, which greatly improves production efficiency and significantly increases the life of stainless steel products.

[0023] 3. The raw materials of the present invention, aluminum oxide, titanium oxide, and zirconium oxide ceramic powders, are all stable and high-temperature resistant. Sodium silicate, used as a binder, ensures formability at room temperature. At high temperatures, the viscous sodium silicate fills the ceramic particles, forming a dense coating that significantly enhances oxidation resistance. The oxide ceramics significantly improve resistance to corrosive media, and the coating has an operating temperature range of 600-1000 degrees Celsius.

[0024] 4. The present invention can be applied to the outer wall of stainless steel by brushing, and can also be applied to the inner wall of a stainless steel pipe by centrifugal method. The coating has strong adhesion and can protect the inside and outside from oxidation and medium corrosion at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0026] Figure 1 This is a flow chart of a method for preparing a high-temperature resistant and anti-oxidation coating for stainless steel according to the present invention;

[0027] Figure 2 The SEM image of the anti-oxidation coating on the stainless steel substrate obtained by the preparation method of the present invention;

[0028] Figure 3 These are physical pictures of an uncoated stainless steel pipe and a stainless steel pipe using embodiments 1 and 2 of the present invention;

[0029] Figure 4 This is a physical diagram of the solution of Example 3 of the present invention.

[0030] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0033] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing in the full text is to include three parallel solutions. Taking "A and / or B as an example", it includes solution A, or solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] Reactors used in the chemical industry are mostly made of stainless steel, which requires both high-temperature resistance and chemical corrosion resistance. Furthermore, chemical stainless steel pipes are used at high temperatures, requiring excellent oxidation and corrosion resistance. To extend the service life of stainless steel and enable long-term use at temperatures of 800-1000 degrees Celsius, an antioxidant and corrosion-resistant coating is applied to its surface. This high-density coating effectively prevents oxygen atoms and corrosive media from penetrating the stainless steel surface, protecting the base material from oxidation and corrosion at high temperatures.

[0035] The invention provides a method for preparing a high-temperature resistant and anti-oxidation coating for stainless steel.

[0036] In the embodiment of the present invention, Figure 1 and Figure 2 As shown, the method for preparing a high-temperature resistant and anti-oxidation coating for stainless steel comprises the following steps:

[0037] Step 1: Weigh the raw materials according to the mass ratio of alumina ceramic powder: titanium oxide ceramic powder: silicon oxide ceramic powder is 1: (0.5-2): (0.5-4); wherein the proportion of titanium oxide ceramic powder can be 0.5, 1, 1.5 or 2, and the proportion of silicon oxide ceramic powder can be 0.5, 1, 1.5, 2, 2.5, 3, 3.5 or 4.

[0038] Step 2: Put the weighed ceramic powder into a ball mill and grind it to obtain ceramic powder;

[0039] Step 3: Place the ball-milled ceramic powder into an oven for drying;

[0040] Step 4: Add dried sodium silicate to the dried ceramic powder, place the ceramic powder and sodium silicate in a container to form a mixed powder, add deionized water to the container, and stir evenly to form a white ceramic slurry;

[0041] Step 5: Apply the prepared ceramic slurry to the stainless steel surface and place it in an oven for drying;

[0042] Step six: Place the dried coating into a high-temperature furnace for sintering, and cool it down with the furnace after sintering to form a high-temperature resistant coating.

[0043] The technical solution of the present invention uses low-cost aluminum oxide, titanium oxide and silicon oxide ceramic powders as the main raw materials and adopts sodium silicate as the inorganic binder, which can not only ensure the economy of the raw materials but also ensure the good processability of the coating. The biggest problem in preparing inorganic coatings on metal surfaces is that the thermal expansion coefficients of the two do not match. During the cooling process, the inorganic coating is easy to break. The ceramic raw materials used in the present invention can form a ceramic solid solution with the passivation layer on the stainless steel surface, thereby solving the problem of the inorganic coating falling off and peeling off on the metal surface. The inorganic coating and the passivation layer on the stainless steel surface complement each other, ensuring the anti-oxidation and corrosion resistance of stainless steel in high-temperature environments.

[0044] Compared with traditional laser cladding technology, the technology of the present invention has low cost, a wide range of raw materials and low cost, which greatly improves production efficiency and significantly increases the life of stainless steel products.

[0045] Furthermore, the raw materials, alumina, titanium oxide, and zirconium oxide ceramic powders, are all stable and high-temperature resistant. Sodium silicate, used as a binder, ensures formability at room temperature. At high temperatures, the viscous sodium silicate fills the ceramic particles, forming a dense coating that significantly enhances oxidation resistance. Oxide ceramics significantly improve resistance to corrosive media, and the coating has an operating temperature range of 600-1000 degrees Celsius.

[0046] The technical solution of the present invention can be brushed on the outer wall of stainless steel, and can also be coated on the inner wall of a stainless steel pipe using a centrifugal method. The coating has strong adhesion and can simultaneously protect the inside and outside from oxidation and medium corrosion.

[0047] from Figure 2 It can be seen that the coating obtained by adopting the technical solution of the present invention has high uniformity and density, and can improve high temperature resistance, oxidation resistance and corrosion resistance.

[0048] In some embodiments, in step 2, the ball mill is a planetary ball mill, the ball-to-material ratio is 3:1, the milling medium is deionized water, the rotation speed is 300 rpm, and the ball milling is performed for 2 hours, so that the powder can be fully mixed.

[0049] In some embodiments, the grinding balls in step 2 are alumina balls, and the diameter of the largest grinding balls in the ball mill is no more than 8 mm, and the diameter of the smallest grinding balls is no less than 3 mm. Specifically, the alumina balls have a relatively high hardness, which can ensure that the powder is fully mixed without affecting the component content. Selecting grinding balls of different diameters can ensure that the large and small balls cooperate and collide with each other, thereby achieving more uniform mixing of the powder. If all the balls are large, the gaps between the large balls will retain smaller powder particles, which is not conducive to uniform mixing. Only when the large and small balls roll together can the large and small particles in the powder be evenly mixed.

[0050] In some embodiments, in step 3, the baking temperature in the oven is 120 degrees Celsius. Specifically, since water is used as the ball milling medium when ball milling aluminum oxide, titanium oxide, and silicon oxide, if the drying temperature is too low, the layers will be very dense, making it difficult to mix them later, while if the temperature is too high, the slurry will easily overflow the container. By drying at 120 degrees Celsius, the water can evaporate faster, and pores will form in the ceramic slurry due to the evaporation of water, ensuring the looseness of the powder and preparing for subsequent mixing with sodium silicate.

[0051] In some embodiments, in step 4, the ceramic powder and sodium silicate are weighed to a mass ratio of 1:8, and the weighed ceramic powder and sodium silicate are then placed in a container. Deionized water is added in an amount of 30% of the mixed powder. Specifically, a 1:8 mass ratio of ceramic powder to sodium silicate results in a coating with good thickness and adhesion. When 30% of the water is added, the coating has a viscosity suitable for application to stainless steel surfaces, thereby improving application performance.

[0052] In some embodiments, the mixed powder is stirred and heated at 80 degrees Celsius in step 4, so that the sodium silicate can be fully dissolved.

[0053] In some embodiments, in step 5, the oven temperature is 150 degrees Celsius, the baking time is 20 minutes, and the coating thickness is 20-30 microns. Specifically, baking at 150 degrees Celsius allows the coating to dry quickly and thoroughly dries the crystal water in the sodium silicate, preventing the coating from absorbing moisture in humid air after baking.

[0054] In some embodiments, in step 6, the sintering temperature is not less than 900 degrees Celsius, and the sintering temperature is 2 hours and then cooled in the furnace. This ensures the sintering effect of the coating and can better form a high-temperature resistant coating on the stainless steel surface.

[0055] In some embodiments, before step 5, the stainless steel surface is first cleaned with a 10% NaOH solution and then rinsed with deionized water. This can clean the oil stains on the stainless steel surface, improve the adhesion of the coating to the stainless steel, and reduce the risk of coating peeling.

[0056] Optionally, a method for preparing a high-temperature resistant and anti-oxidation coating for stainless steel comprises the following steps:

[0057] Step 1, weighing materials: weighing the aluminum oxide ceramic powder: titanium oxide ceramic powder: silicon oxide ceramic powder in a ratio of 1: (0.5-2): (0.5-4) according to the mass percentage.

[0058] Step 2, ball milling: pour the weighed ceramic powder into a ball mill, add deionized water for wet ball milling, the ball mill is a planetary ball mill, the grinding medium is alumina balls, the largest alumina ball in the ball mill has a diameter of no more than 8 mm, the smallest diameter is no less than 3 mm, the ball-to-material ratio is 3:1, the ball mill rotation speed is 300 rpm, and the ball milling is carried out for 2 hours.

[0059] Step 3: Drying: Place the ball-milled ceramic slurry in a 120-degree Celsius oven to dry it into dry powder.

[0060] Step 4. Preparation of slurry: Mix the dried ceramic powder with the inorganic binder sodium silicate powder. The mass ratio of ceramic powder to sodium silicate powder is 1:8. After stirring evenly, gradually add deionized water and stir. The amount of deionized water added is 30% of the entire powder. In order to ensure the full dissolution of sodium silicate, heat the solution to 80 degrees Celsius and stir until a uniform ceramic slurry is formed.

[0061] Step 5: Coating and Drying: Spray the ceramic slurry onto the stainless steel surface using a compressed air spray gun. Then dry it at 150 degrees Celsius for 20 minutes to form a coating with a thickness of 20-30 microns.

[0062] Step six, sintering: sinter the coating at 1000 degrees Celsius for 2 hours to form a dense high-temperature and corrosion-resistant coating, and then slowly cool it down in the furnace.

[0063] Optionally, in Example 1, a method for preparing a high-temperature resistant and anti-oxidation coating for stainless steel comprises the following steps:

[0064] Step 1, weighing materials: weighing alumina, titanium oxide and silicon oxide according to a mass ratio of 1:2:1 of alumina ceramic powder: titanium oxide ceramic powder: silicon oxide ceramic powder.

[0065] Step 2: Ball milling: Pour the weighed ceramic powder into a ball mill for wet ball milling. Use deionized water as the medium and alumina balls as the grinding medium. The ball mill rotates at a speed of 300 rpm for 2 hours.

[0066] Step 3: Drying: The ball-milled ceramic powder is placed in an oven at 120 degrees Celsius to dry to form ceramic powder.

[0067] Step 4, preparation of slurry: Mix the dried ceramic powder with the inorganic binder sodium silicate powder in a mass ratio of ceramic powder: sodium silicate = 1:8. After stirring evenly, gradually add deionized water and stir. The amount of deionized water added is 30% of the entire powder. In order to ensure the full dissolution of sodium silicate, heat the solution to 80 degrees Celsius and stir until a uniform ceramic slurry is formed.

[0068] Step 5: Coating and Drying: Spray the ceramic slurry onto the stainless steel surface using a compressed air spray gun. Then dry it at 150 degrees Celsius for 20 minutes to form a coating with a thickness of 20-30 microns.

[0069] Step 6: Sintering: Sinter the coating at 1000 degrees Celsius for 2 hours and then slowly cool it in the furnace to form a dense, high-temperature and corrosion-resistant coating.

[0070] Before step 5, the surface of the stainless steel sample is cleaned: the surface of the stainless steel sample is first cleaned with 10% NaOH solution and then rinsed with deionized water to clean the oil stains on the surface.

[0071] Optionally, in Example 2, a method for preparing a high-temperature resistant and anti-oxidation coating for stainless steel comprises the following steps:

[0072] Step 1, weighing materials: weighing alumina, titanium oxide and silicon oxide according to a mass ratio of 1:1:1 of alumina ceramic powder: titanium oxide ceramic powder: silicon oxide ceramic powder.

[0073] Step 2: Ball milling: Pour the weighed ceramic powder into a ball mill for wet ball milling. Use deionized water as the medium and alumina balls as the grinding medium. The ball mill rotates at a speed of 300 rpm for 2 hours.

[0074] Step 3: Drying: The ball-milled ceramic powder is placed in an oven at 120 degrees Celsius to dry to form ceramic powder.

[0075] Step 4, preparation of slurry: Mix the dried ceramic powder with the inorganic binder sodium silicate powder in a mass ratio of ceramic powder: sodium silicate = 1:8. After stirring evenly, gradually add deionized water and stir. The amount of deionized water added is 30% of the entire powder. In order to ensure the full dissolution of sodium silicate, heat the solution to 80 degrees Celsius and stir until a uniform ceramic slurry is formed.

[0076] Step 5: Coating and Drying: Spray the ceramic slurry onto the stainless steel surface using a compressed air spray gun. Then dry it at 150 degrees Celsius for 20 minutes to form a coating with a thickness of 30-40 microns.

[0077] Step 6: Sintering: Sinter the coating at 900 degrees Celsius for 2 hours and then slowly cool it in the furnace to form a dense, high-temperature and corrosion-resistant coating.

[0078] Before step 5, the surface of the stainless steel sample is cleaned: the surface of the stainless steel sample is first cleaned with 10% NaOH solution and then rinsed with deionized water to clean the oil stains on the surface.

[0079] Optionally, in Example 3, a method for preparing a high-temperature resistant and anti-oxidation coating for stainless steel comprises the following steps:

[0080] Step 1, weighing materials: weighing alumina, titanium oxide and silicon oxide according to a mass ratio of 1:2:1 of alumina ceramic powder: titanium oxide ceramic powder: silicon oxide ceramic powder.

[0081] Step 2: Ball milling: Pour the weighed ceramic powder into a ball mill for wet ball milling. Use deionized water as the medium and alumina balls as the grinding medium. The ball mill rotates at a speed of 300 rpm for 2 hours.

[0082] Step 3: Drying: The ball-milled ceramic powder is placed in an oven at 120 degrees Celsius to dry to form ceramic powder.

[0083] Step 4, preparation of slurry: Mix the dried ceramic powder with the inorganic binder sodium silicate powder in a mass ratio of ceramic powder: sodium silicate = 1:8. After stirring evenly, gradually add deionized water and stir. The amount of deionized water added is 30% of the entire powder. In order to ensure the full dissolution of sodium silicate, heat the solution to 80 degrees Celsius and stir until a uniform ceramic slurry is formed.

[0084] Step 5: Coating and Drying: Spray the ceramic slurry onto the stainless steel surface using a compressed air spray gun. Then dry it at 150 degrees Celsius for 20 minutes to form a coating with a thickness of 20-25 microns.

[0085] Step 6: Sintering: Sinter the coating at 1000 degrees Celsius for 2 hours and then slowly cool it in the furnace to form a dense, high-temperature and corrosion-resistant coating.

[0086] Before step 5, the surface of the stainless steel sample is cleaned: the surface of the stainless steel sample is first cleaned with 10% NaOH solution and then rinsed with deionized water to clean the oil stains on the surface.

[0087] Figure 3In the figure, a is a physical picture of the stainless steel pipe, b is a physical picture of the stainless steel pipe coated with the above embodiment 1 after being kept at 900 degrees Celsius for 5 hours, c is a physical picture of the stainless steel pipe coated with the above embodiment 2 after being kept at 900 degrees Celsius for 5 hours, and d is a physical picture of the uncoated stainless steel pipe after being kept at 900 degrees Celsius for 5 hours. Figure 4 This image shows a stainless steel cup coated with Example 3 after being held at 900°C for 5 hours. As can be seen, after 5 hours at 900°C, the uncoated stainless steel tube is severely oxidized, forming a black oxide layer on the surface. However, the stainless steel tubes / cups coated with Examples 1, 2, and 3 maintain a good appearance and are not oxidized. This demonstrates that the coatings of Examples 1, 2, and 3 exhibit excellent high-temperature resistance and oxidation resistance, exhibit no flaking, and effectively protect the stainless steel tube.

[0088] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a high temperature resistant and anti-oxidation coating for stainless steel, characterized in that: The steps include: Step 1: weigh the raw materials according to the mass ratio of alumina ceramic powder: titanium oxide ceramic powder: silicon oxide ceramic powder is 1: (0.5-2): (0.5-4); Step 2: putting the weighed ceramic powder into a ball mill and milling it to obtain ceramic powder; Step 3: Place the ball-milled ceramic powder into an oven for drying; Step 4: Add dried sodium silicate to the dried ceramic powder, place the ceramic powder and sodium silicate in a container to form a mixed powder, add deionized water to the container, and stir evenly to form a white ceramic slurry; Step 5: Apply the prepared ceramic slurry to the stainless steel surface and place it in an oven for drying; Step six: Place the dried coating into a high-temperature furnace for sintering, and cool it down with the furnace after sintering to form a high-temperature resistant coating.

2. The method for preparing a high-temperature resistant and anti-oxidation coating for stainless steel according to claim 1, characterized in that: In the step 2, the ball mill is a planetary ball mill, the ball-to-material ratio is 3:1, the ball milling medium is deionized water, the rotation speed is 300 rpm, and the ball milling mixing is performed for 2 hours.

3. The method for preparing a high temperature resistant and anti-oxidation coating for stainless steel according to claim 2, wherein: The grinding balls in step 2 are alumina balls, the diameter of the largest grinding ball in the ball mill is no more than 8 mm, and the diameter of the smallest grinding ball is no less than 3 mm.

4. The method for preparing a high temperature resistant and anti-oxidation coating for stainless steel according to claim 3, wherein: In step three, the baking temperature in the oven is 120 degrees Celsius.

5. The method for preparing a high temperature resistant and anti-oxidation coating for stainless steel according to claim 1, wherein: In step 4, the ceramic powder and sodium silicate are weighed in a mass ratio of 1:8, and the weighed ceramic powder and sodium silicate are placed in a container. The amount of deionized water added is 30% of the mixed powder.

6. The method for preparing a high temperature resistant and anti-oxidation coating for stainless steel according to claim 5, characterized in that: In step 4, the mixed powder is heated while being stirred, and the heating temperature is 80 degrees Celsius.

7. The method for preparing a high temperature resistant and anti-oxidation coating for stainless steel according to claim 1, characterized in that: In the step 5, the oven temperature is 150 degrees Celsius, the baking time is 20 minutes, and the thickness of the coating is 20-30 microns.

8. The method for preparing a high temperature resistant and anti-oxidation coating for stainless steel according to claim 1, wherein: In step six, the sintering temperature is not less than 900 degrees Celsius, and the sintering is carried out for 2 hours and then cooled in the furnace.

9. The method for preparing a high temperature resistant and anti-oxidation coating for stainless steel according to claim 1, characterized in that: Before step five, the stainless steel surface is first cleaned with a 10% NaOH solution and then rinsed with deionized water.

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