High-temperature-resistant and wear-resistant stainless steel for pneumatic cylinders and preparation method thereof

Abstract

The present invention relates to the technical field of stainless steel, and specifically discloses a high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders and a preparation method thereof. The present invention introduces a plurality of elements into the steel to enhance the mechanical properties, chemical stability, wear resistance, corrosion resistance and high-temperature stability of the steel, then laser-clads an alloy layer on the surface of the steel to further improve the wear resistance and high-temperature oxidation resistance of the material, then prepares a multi-layer composite film on the surface of the steel to protect the steel, and finally forms a self-lubricating ceramic coating on the surface of the material, thereby obtaining stainless steel for pneumatic cylinders with good high-temperature oxidation resistance, wear resistance, corrosion resistance and mechanical properties.

Description

Technical Field

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

[0002] The development of cylinders, as pneumatic actuators, is closely tied to industrial progress. Initially, cylinders were used only in steam engines, where steam pushed pistons to drive machinery. With the further development of industrial technology and the widespread adoption of compressed air systems, cylinders became a key component of industrial automation. Early cylinders were forged from cast iron or steel. In high-temperature environments, when cast iron or steel comes into contact with air, it oxidizes with oxygen, water vapor, and other gases in the air, forming a loose, porous oxide scale on the surface. This scale not only affects the cylinder's sealing properties but also accelerates fatigue damage. The shedding of oxidized particles also exacerbates wear and reduces the cylinder's service life. Therefore, developing high-temperature-resistant and wear-resistant cylinders is key to improving the reliability of industrial equipment. Summary of the Invention

[0003] The purpose of the present invention is to provide a high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders and a preparation method thereof, so as to solve the problem that the cylinder is not wear-resistant and is easily oxidized to form an oxide layer at high temperature, which leads to a decrease in the cylinder's sealing performance and service life.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] A method for preparing high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders, specifically comprising:

[0006] Step 1: Use stainless steel, ferromolybdenum, ferrocobalt, ferrotungsten, ferroaluminum, ferrovanadium, ferrotitanium, ferrocerium and ferroboron as raw materials to smelt aluminum-containing heat-resistant stainless steel;

[0007] Step 2: Using laser cladding technology, the mixed metal powder is laser clad on the surface of the aluminum-containing heat-resistant stainless steel to form a high-temperature wear-resistant alloy layer to obtain high-temperature wear-resistant stainless steel;

[0008] Step 3: immersing the high-temperature wear-resistant stainless steel in chromium oxide sol, aluminum oxide sol, and silicon oxide sol in sequence to form a multi-layer high-temperature oxidation film on the surface of the high-temperature wear-resistant stainless steel to obtain high-temperature oxidation-resistant wear-resistant stainless steel;

[0009] Step 4: spray self-lubricating phosphate ceramic coating on the surface of high-temperature resistant, oxidation-resistant and wear-resistant stainless steel, dry at 60-70°C, heat to 300-350°C and sinter for 3-4 hours, and cool to room temperature after sintering to obtain high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders.

[0010] As a limitation of the present invention, in step 1, the mass fraction of each element in the aluminum-containing heat-resistant stainless steel is:

[0011] C: 0.06~0.08%, Si: 0.3~0.5%, Mn: 0.8~1.0%, Cr: 19~21%, Ni: 8.0~10.0%, Mo: 0.15~0.2%, W: 0.35~0.45%, Co: 0.14~0.20%, Al: 2.0~2.5%, V: 0.15~0.20%, Ti: 0.2~0.3%, B: 0.005~0.01%, Ce≤0.04%, P≤0.04%, S≤0.05%, and the balance is iron.

[0012] As a limitation of the present invention, step 1 is specifically:

[0013] The stainless steel is heated to 1680-1700°C for melting, and then ferromolybdenum, ferrocobalt and ferrotungsten are added for smelting. After the ferromolybdenum, ferrocobalt and ferrotungsten are melted, a slag remover is added for slag removal. 15-20 minutes before the molten steel is discharged from the furnace, ferroaluminum, ferrovanadium and ferrotitanium are added for smelting. After the ferroaluminum, ferrovanadium and ferrotitanium are melted, a slag remover is added for slag removal. 5-8 minutes before the molten steel is discharged from the furnace, a deoxidizer is added for deoxidation. The molten steel is discharged from the furnace at 1650-1680°C and poured into a ladle. Ferrocereium, ferroboron and a deoxidizer are added to the molten steel in the ladle. After standing for 5 minutes, the molten steel is cast at 1580-1600°C under argon protection to obtain aluminum-containing heat-resistant stainless steel.

[0014] Introducing an appropriate amount of aluminum into steel helps form an aluminum oxide protective film, which synergizes with the chromium element in the steel to form a composite oxide layer composed of aluminum oxide and chromium oxide, significantly improving the steel's oxidation resistance at high temperatures.

[0015] As a limitation of the present invention, the slag remover is a calcium aluminate slag remover, and the amount of the slag remover added each time is 1-1.5% of the mass of the aluminum-containing heat-resistant stainless steel; the deoxidizer is one of a silicon aluminum calcium barium deoxidizer and a silicon calcium manganese deoxidizer, and the amount of the deoxidizer added each time is 0.1-0.5% of the mass of the aluminum-containing heat-resistant stainless steel.

[0016] During the smelting process, calcium aluminate slag remover is added. The calcium oxide and aluminum oxide in calcium aluminate can react with the oxides in the molten steel (such as iron oxide and silicon oxide) to form a low-melting-point composite slag, which reduces the slag viscosity and promotes the floating of inclusions in the molten steel. The calcium aluminate slag has a strong adsorption capacity for sulfides in the molten steel, reduces the sulfur content in the steel, and improves the purity of the steel. The formed liquid slag layer can also prevent the secondary oxidation of the molten steel; the addition of silicon aluminum calcium barium deoxidizer or silicon calcium manganese deoxidizer helps to deep deoxidation and desulfurization and optimize the purity of the molten steel.

[0017] As a limitation of the present invention, in step 2, the mixed metal powder includes, by mass fraction, 18-22% chromium powder, 4-8% aluminum powder, 2-4% vanadium titanium powder, 1-3% copper powder, 0.1-0.5% zirconium powder, and the balance is nickel powder.

[0018] As a limitation of the present invention, step 2 is specifically:

[0019] Nickel powder, chromium powder, aluminum powder, vanadium titanium powder, copper powder and zirconium powder are mixed and ball milled for 10-20 minutes to obtain mixed metal powder with a particle size of 280-300 mesh. The aluminum-containing heat-resistant stainless steel is polished with sandpaper, washed with ethanol and deionized water, dried and heated to 250-280°C for preheating. Under argon protection, the mixed metal powder is clad on the surface of the aluminum-containing heat-resistant stainless steel. During the cladding process, the laser power is 2-2.2KW, the spot diameter is 1-3mm, the scanning speed is 10-13mm / s, the powder feeding speed is 20-25g / min, and the argon flow rate is 15-20L / min. After the cladding is completed, the temperature is raised to 600-640°C and kept warm for 2-4h. After the insulation is completed, it is cooled to obtain high-temperature wear-resistant stainless steel.

[0020] As a limitation of the present invention, step 3 is specifically:

[0021] Chromium nitrate is added to deionized water, heated to 80-90°C and stirred continuously to fully dissolve the chromium nitrate, and then the pH of the chromium nitrate solution is adjusted to 5-6 with aqueous ammonia, and the mixture is stirred for 20-24 hours and allowed to stand for 6-12 hours to obtain a chromium oxide sol with a chromium nitrate concentration of 0.03-0.05 g / mL;

[0022] Aluminum isopropoxide was added to deionized water, stirred for 2-4 hours, and then the pH was adjusted to 2-3 with concentrated nitric acid. After stirring for 1-1.5 hours in a sealed container, the mixture was allowed to stand for 8-12 hours in a water bath heated at 70-80°C to obtain an alumina sol with an aluminum isopropoxide concentration of 0.08-0.1 g / mL.

[0023] Add ethyl orthosilicate to anhydrous ethanol, stir for 0.5-1 hour, then heat to 60-70°C and add deionized water. Adjust the pH to 2-3 with concentrated nitric acid, continue stirring for 1-2 hours, and let stand at room temperature for 4-6 hours to obtain a silica sol with an ethyl orthosilicate concentration of 0.4-0.6 g / mL;

[0024] Immerse the high-temperature wear-resistant stainless steel in chromium oxide sol for 60-90 seconds. After ensuring that the sol completely covers the high-temperature wear-resistant stainless steel, slowly extract the high-temperature wear-resistant stainless steel at a rate of 5-10 cm / min, dry it at room temperature for 20-30 minutes, then heat it to 90-100°C and continue drying it for 20-30 minutes. Then immerse it in alumina sol and silica sol respectively, and treat the high-temperature wear-resistant stainless steel in the same way. Finally, place it in a heating furnace, heat it to 600-620°C at a rate of 10-15°C / min and keep it warm for 1-2 hours to obtain high-temperature oxidation-resistant wear-resistant stainless steel.

[0025] The chromium oxide protective layer helps to protect the steel, inhibit oxygen diffusion, and improve the high-temperature stability of the steel. However, if the steel is exposed to high temperatures for a long time, the chromium oxide protective layer of the steel may evaporate and become ineffective. Therefore, an aluminum oxide protective layer and a silicon oxide protective layer are added to the chromium oxide protective layer. The thermal expansion coefficient of aluminum oxide is not much different from that of chromium oxide, which can keep the protective layer relatively intact and without cracks. Aluminum oxide is converted into a stable α phase at high temperature and has a lower oxygen diffusion coefficient than chromium oxide, continuing to protect the steel. The diffusion coefficient of the silicon oxide layer on the surface is extremely low, and during the sintering process, silicon and aluminum elements can diffuse into each other, improving the anti-stripping ability of the protective layer and the surface integrity and density.

[0026] As a limitation of the present invention, in step 4, the preparation method of the self-lubricating phosphate ceramic coating is:

[0027] Aluminum dihydrogen phosphate is added to deionized water and stirred evenly to obtain an aluminum dihydrogen phosphate solution. Polydimethylsiloxane defoamer and phosphate dispersant are added to the aluminum dihydrogen phosphate solution and stirred evenly. Mullite whiskers, silicon nitride and molybdenum sulfide are added and ultrasonic dispersion is performed for 20-30 minutes to obtain a self-lubricating phosphate ceramic coating.

[0028] Mullite whiskers are a type of high-strength, high-modulus aluminum silicate single crystal fiber with high compatibility with the base coating. Mullite whiskers enhance the hardness and wear resistance of the coating. The whiskers form a network that hinders the migration of phosphate particles, bridges cracks, delays crack propagation, improves the density of the coating, and avoids cracking. In addition, at high temperatures, a liquid phase (aluminum oxide-silicon dioxide-phosphorus pentoxide) is generated on the surface of the whiskers, which promotes the healing of microcracks in the coating and gives the coating a certain self-repair ability.

[0029] As a limitation of the present invention, the mass ratio of aluminum dihydrogen phosphate, mullite whiskers, silicon nitride, and molybdenum sulfide is (15-20):(25-30):(12-16):(8-12); the mass fraction of the polydimethylsiloxane defoamer in the self-lubricating phosphate ceramic coating is 0.2-0.5%, and the mass fraction of the phosphate ester dispersant is 0.5-2%.

[0030] A high-temperature-resistant and wear-resistant stainless steel for a pneumatic cylinder is processed by adopting the above-mentioned preparation method.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention introduces elements such as molybdenum, cobalt, tungsten, aluminum, vanadium, titanium, cerium, and boron into steel. Among them, molybdenum can form stable molybdenum oxide, improve the corrosion resistance of steel, and synergize with chromium to inhibit the precipitation of σ phase and avoid intergranular corrosion; cobalt forms a solid solution to strengthen the austenite matrix, thereby improving the high-temperature strength and wear resistance of steel; tungsten and titanium form carbides to improve the red hardness and high-temperature strength of steel; vanadium can refine the grains, inhibit the precipitation of σ phase, and improve the high-temperature stability of steel; aluminum can form an aluminum oxide protective film, and the composite oxide layer formed by synergistically acting with chromium improves the high-temperature oxidation resistance mentioned above; cerium can improve the hot workability of steel and improve the high-temperature oxidation resistance of steel; boron can improve the hardenability and wear resistance of steel; the design of the ratio of each element improves the mechanical properties, chemical stability, wear resistance and corrosion resistance of steel, and gives steel high-temperature oxidation resistance, so that it has good high-temperature stability.

[0033] Laser cladding is used to form a nickel-chromium-aluminum-vanadium-titanium-copper-zirconium cladding alloy layer on the surface of the smelted steel. Nickel, as the matrix element of the alloy layer, has good high-temperature stability. The addition of chromium helps to form a passivation film, thereby improving the material's oxidation resistance and corrosion resistance. Aluminum and titanium work synergistically to form a γ phase, thereby improving the material's high-temperature oxidation resistance and high-temperature creep resistance. Vanadium and titanium form a carbide hard phase, thereby improving the material's hardness and wear resistance. Copper and zirconium improve the material's thermal conductivity and corrosion resistance.

[0034] On the basis of the alloy layer, a multi-layer composite film is further formed by chromium oxide sol, aluminum oxide sol and silicon oxide sol. The inner layer of chromium oxide has good bonding with the substrate, the middle layer of aluminum oxide can prevent the chromium oxide from volatilizing and failing under long-term high temperature, and the outer layer of silicon oxide prevents the penetration of gases such as sulfur dioxide and carbon dioxide into the steel under high temperature.

[0035] Finally, a phosphate coating containing mullite whiskers and molybdenum sulfide is sprayed on the surface of the material, and a ceramic coating is formed after sintering. The mullite whiskers are highly compatible with the coating matrix and can improve the wear resistance of the coating. Molybdenum sulfide can generate a lubricating film during friction, reducing the loss of the coating during friction and wear, and improving the wear resistance of the material. DETAILED DESCRIPTION

[0036] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0037] Stainless steel (304 stainless steel, particle size: 100 mesh), ferromolybdenum (particle size: 100 mesh, molybdenum: 60%), ferrocobalt (particle size: 100 mesh, cobalt: 70%), ferrotungsten (particle size: 100 mesh, tungsten: 75%), ferroaluminum (particle size: 100 mesh, aluminum: 30%), ferrovanadium (particle size: 100 mesh, vanadium: 50%), ferrotitanium (particle size: 100 mesh, titanium: 30%), ferrocerium (particle size: 100 mesh, cerium: 25%), ferroboron (particle size: 100 mesh, boron: 17%), calcium aluminate deslagging agent (calcium oxide: 45-50%, aluminum oxide: 40-45%, magnesium oxide: 3-10%), silicon aluminum calcium barium deoxidizer (silicon: 50%). -60%, aluminum: 15-20%, calcium: 10-15%, barium: 5-10%), nickel powder (particle size: 200 mesh, purity: ≥99.9%), chromium powder (particle size: 200 mesh, purity: ≥99.9%), aluminum powder (particle size: 100 mesh, purity: ≥99.9%), vanadium-titanium powder (particle size: 100 mesh, vanadium: 45%), copper powder (particle size: 100 mesh, purity: ≥99.9%), zirconium powder (particle size: 200 mesh, purity: ≥99.9%), mullite whiskers (diameter: 0.2-0.5μm, length: 20-30μm), silicon nitride (particle size: 200 mesh), molybdenum sulfide (particle size: 200 mesh).

[0038] Example 1: A method for preparing high-temperature resistant and wear-resistant stainless steel for a pneumatic cylinder, specifically:

[0039] Step 1: After heating the stainless steel to 1700°C and melting it, add ferromolybdenum, ferrocobalt and ferrottungsten for smelting. After the ferromolybdenum, ferrocobalt and ferrottungsten are melted, add a calcium aluminate deslagging agent containing 1% of the mass of the aluminum heat-resistant stainless steel for deslagging. 15 minutes before the molten steel is discharged from the furnace, add ferroaluminum, ferrovanadium and ferrotitanium for smelting. After the ferroaluminum, ferrovanadium and ferrotitanium are melted, add a calcium aluminate deslagging agent containing 1% of the mass of the aluminum heat-resistant stainless steel for deslagging. 5 minutes before the molten steel is discharged from the furnace, add a silicon aluminum calcium barium deoxidizer containing 0.5% of the mass of the aluminum heat-resistant stainless steel for deoxidation. The molten steel is discharged from the furnace at 1680°C and poured into a ladle. Ferrocere, ferroboron and a silicon aluminum calcium barium deoxidizer containing 0.5% of the mass of the aluminum heat-resistant stainless steel are added to the molten steel in the ladle. After standing for 5 minutes, the molten steel is cast at 1600°C under argon protection to obtain aluminum heat-resistant stainless steel.

[0040] In the aluminum-containing heat-resistant stainless steel prepared in step 1, the mass fractions of each element are: C: 0.075%, Si: 0.38%, Mn: 0.86%, Cr: 19.25%, Ni: 8.35%, Mo: 0.17%, W: 0.37%, Co: 0.15%, Al: 2.0%, V: 0.17%, Ti: 0.22%, B: 0.007%, Ce: 0.01%, P: 0.03%, S: 0.025%, and the balance is iron;

[0041] Step 2: By mass fraction, 68.8% nickel powder, 20% chromium powder, 6% aluminum powder, 4% vanadium titanium powder, 1% copper powder, and 0.2% zirconium powder were mixed and ball-milled for 20 minutes to obtain a mixed metal powder with a particle size of 300 mesh. The aluminum-containing heat-resistant stainless steel was polished with sandpaper, washed with ethanol and deionized water, dried, and then heated to 280°C for preheating. Under argon protection, the mixed metal powder was clad on the surface of the aluminum-containing heat-resistant stainless steel. During the cladding process, the laser power was 2KW, the spot diameter was 2mm, the scanning speed was 10mm / s, the powder feeding speed was 20g / min, and the argon flow rate was 18L / min. After the cladding was completed, the temperature was raised to 600°C and kept warm for 4h. After the insulation was completed, it was cooled to obtain high-temperature wear-resistant stainless steel;

[0042] Step 3: Chromium nitrate was added to deionized water, and the temperature was raised to 90°C with continuous stirring to fully dissolve the chromium nitrate to obtain a 0.04 g / mL chromium nitrate solution. The pH of the chromium nitrate solution was then adjusted to 5 with aqueous ammonia. The solution was stirred for 24 hours and then allowed to stand for 12 hours to obtain a chromium oxide sol.

[0043] Step 4: Aluminum isopropoxide was added to deionized water and stirred for 2 h to obtain an aluminum isopropoxide solution with a concentration of 0.08 g / mL. The pH was then adjusted to 3 with concentrated nitric acid. The mixture was stirred in a sealed container for 1.5 h and then allowed to stand in a water bath at 70-80°C for 12 h to obtain an alumina sol.

[0044] Step 5: Add ethyl orthosilicate to anhydrous ethanol, stir for 1 hour, then heat to 70°C and add deionized water to obtain a 0.5 g / mL ethyl orthosilicate ethanol aqueous solution (the volume ratio of ethanol to deionized water is 2:1). Adjust the pH to 3 with concentrated nitric acid, continue stirring for 2 hours, and let stand at room temperature for 6 hours to obtain a silica sol.

[0045] Step 6: Immerse the high-temperature wear-resistant stainless steel in chromium oxide sol for 60 seconds. After ensuring that the sol completely covers the high-temperature wear-resistant stainless steel, slowly extract the high-temperature wear-resistant stainless steel at a rate of 5 cm / min, dry it at room temperature for 30 minutes, heat it to 90°C and continue drying for 30 minutes, then immerse it in alumina sol and silica sol respectively, treat the high-temperature wear-resistant stainless steel in the same way, finally, place it in a heating furnace, heat it to 600°C at a rate of 10°C / min and keep it warm for 2 hours to obtain high-temperature oxidation-resistant wear-resistant stainless steel;

[0046] Step 7: Add 15 parts of aluminum dihydrogen phosphate to 50 parts of deionized water by mass and stir evenly to obtain an aluminum dihydrogen phosphate solution. Add 0.5% by mass of polydimethylsiloxane defoamer and 1% by mass of phosphate dispersant to the aluminum dihydrogen phosphate solution and stir evenly. Then, add 25 parts of mullite whiskers, 12 parts of silicon nitride and 8 parts of molybdenum sulfide and ultrasonically disperse for 30 minutes to obtain a self-lubricating phosphate ceramic coating. Spray the self-lubricating phosphate ceramic coating on the surface of high-temperature resistant, oxidation-resistant and wear-resistant stainless steel. After drying at 70°C, heat to 300°C and sinter for 4 hours. After sintering, cool to room temperature to obtain high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders.

[0047] Example 2: A method for preparing high-temperature resistant and wear-resistant stainless steel for a pneumatic cylinder, specifically comprising:

[0048] Step 1: After heating the stainless steel to 1700°C and melting it, add ferromolybdenum, ferrocobalt and ferrottungsten for smelting. After the ferromolybdenum, ferrocobalt and ferrottungsten are melted, add a calcium aluminate deslagging agent containing 1% of the mass of the aluminum heat-resistant stainless steel for deslagging. 15 minutes before the molten steel is discharged from the furnace, add ferroaluminum, ferrovanadium and ferrotitanium for smelting. After the ferroaluminum, ferrovanadium and ferrotitanium are melted, add a calcium aluminate deslagging agent containing 1% of the mass of the aluminum heat-resistant stainless steel for deslagging. 5 minutes before the molten steel is discharged from the furnace, add a silicon aluminum calcium barium deoxidizer containing 0.5% of the mass of the aluminum heat-resistant stainless steel for deoxidation. The molten steel is discharged from the furnace at 1680°C and poured into a ladle. Ferrocere, ferroboron and a silicon aluminum calcium barium deoxidizer containing 0.5% of the mass of the aluminum heat-resistant stainless steel are added to the molten steel in the ladle. After standing for 5 minutes, the molten steel is cast at 1600°C under argon protection to obtain aluminum heat-resistant stainless steel.

[0049] In the aluminum-containing heat-resistant stainless steel prepared in step 1, the mass fractions of each element are: C: 0.075%, Si: 0.38%, Mn: 0.86%, Cr: 19.25%, Ni: 8.35%, Mo: 0.17%, W: 0.37%, Co: 0.16%, Al: 2.2%, V: 0.18%, Ti: 0.22%, B: 0.007%, Ce: 0.03%, P: 0.03%, S: 0.025%, and the balance is iron;

[0050] Step 2: By mass fraction, 67.8% nickel powder, 21% chromium powder, 7% aluminum powder, 3% vanadium titanium powder, 1% copper powder, and 0.2% zirconium powder were mixed and ball-milled for 20 minutes to obtain a mixed metal powder with a particle size of 300 mesh. The aluminum-containing heat-resistant stainless steel was polished with sandpaper, washed with ethanol and deionized water, dried, and then heated to 280°C for preheating. Under argon protection, the mixed metal powder was clad on the surface of the aluminum-containing heat-resistant stainless steel. During the cladding process, the laser power was 2KW, the spot diameter was 2mm, the scanning speed was 10mm / s, the powder feeding speed was 20g / min, and the argon flow rate was 18L / min. After the cladding was completed, the temperature was raised to 600°C and kept warm for 4h. After the insulation was completed, it was cooled to obtain high-temperature wear-resistant stainless steel;

[0051] Step 3: Chromium nitrate was added to deionized water, and the temperature was raised to 90°C with continuous stirring to fully dissolve the chromium nitrate to obtain a 0.04 g / mL chromium nitrate solution. The pH of the chromium nitrate solution was then adjusted to 5 with aqueous ammonia. The solution was stirred for 24 hours and then allowed to stand for 12 hours to obtain a chromium oxide sol.

[0052] Step 4: Aluminum isopropoxide was added to deionized water and stirred for 2 h to obtain an aluminum isopropoxide solution with a concentration of 0.08 g / mL. The pH was then adjusted to 3 with concentrated nitric acid. The mixture was stirred in a sealed container for 1.5 h and then allowed to stand in a water bath at 70-80°C for 12 h to obtain an alumina sol.

[0053] Step 5: Add ethyl orthosilicate to anhydrous ethanol, stir for 1 hour, then heat to 70°C and add deionized water to obtain a 0.5 g / mL ethyl orthosilicate ethanol aqueous solution (the volume ratio of ethanol to deionized water is 2:1). Adjust the pH to 3 with concentrated nitric acid, continue stirring for 2 hours, and let stand at room temperature for 6 hours to obtain a silica sol.

[0054] Step 6: Immerse the high-temperature wear-resistant stainless steel in chromium oxide sol for 60 seconds. After ensuring that the sol completely covers the high-temperature wear-resistant stainless steel, slowly extract the high-temperature wear-resistant stainless steel at a rate of 5 cm / min, dry it at room temperature for 30 minutes, heat it to 90°C and continue drying for 30 minutes, then immerse it in alumina sol and silica sol respectively, treat the high-temperature wear-resistant stainless steel in the same way, finally, place it in a heating furnace, heat it to 600°C at a rate of 10°C / min and keep it warm for 2 hours to obtain high-temperature oxidation-resistant wear-resistant stainless steel;

[0055] Step 7: Add 17 parts of aluminum dihydrogen phosphate to 50 parts of deionized water by mass and stir evenly to obtain an aluminum dihydrogen phosphate solution. Add 0.5% by mass of a polydimethylsiloxane defoamer and 1% by mass of a phosphate dispersant to the aluminum dihydrogen phosphate solution and stir evenly. Then, add 27 parts of mullite whiskers, 14 parts of silicon nitride and 10 parts of molybdenum sulfide and ultrasonically disperse for 30 minutes to obtain a self-lubricating phosphate ceramic coating. Spray the self-lubricating phosphate ceramic coating on the surface of the high-temperature resistant, oxidation-resistant and wear-resistant stainless steel. After drying at 70°C, heat it to 300°C and sinter it for 4 hours. After sintering, cool it to room temperature to obtain high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders.

[0056] Example 3: A method for preparing high-temperature resistant and wear-resistant stainless steel for a pneumatic cylinder, specifically comprising:

[0057] Step 1: After heating the stainless steel to 1700°C and melting it, add ferromolybdenum, ferrocobalt and ferrottungsten for smelting. After the ferromolybdenum, ferrocobalt and ferrottungsten are melted, add a calcium aluminate deslagging agent containing 1% of the mass of the aluminum heat-resistant stainless steel for deslagging. 15 minutes before the molten steel is discharged from the furnace, add ferroaluminum, ferrovanadium and ferrotitanium for smelting. After the ferroaluminum, ferrovanadium and ferrotitanium are melted, add a calcium aluminate deslagging agent containing 1% of the mass of the aluminum heat-resistant stainless steel for deslagging. 5 minutes before the molten steel is discharged from the furnace, add a silicon aluminum calcium barium deoxidizer containing 0.5% of the mass of the aluminum heat-resistant stainless steel for deoxidation. The molten steel is discharged from the furnace at 1680°C and poured into a ladle. Ferrocere, ferroboron and a silicon aluminum calcium barium deoxidizer containing 0.5% of the mass of the aluminum heat-resistant stainless steel are added to the molten steel in the ladle. After standing for 5 minutes, the molten steel is cast at 1600°C under argon protection to obtain aluminum heat-resistant stainless steel.

[0058] In the aluminum-containing heat-resistant stainless steel prepared in step 1, the mass fractions of each element are: C: 0.075%, Si: 0.38%, Mn: 0.86%, Cr: 19.25%, Ni: 8.35%, Mo: 0.17%, W: 0.37%, Co: 0.15%, Al: 2.5%, V: 0.2%, Ti: 0.3%, B: 0.007%, Ce: 0.03%, P: 0.03%, S: 0.025%, and the balance is iron;

[0059] Step 2: 66.8% nickel powder, 22% chromium powder, 8% aluminum powder, 2% vanadium titanium powder, 1% copper powder, and 0.2% zirconium powder were mixed by mass fraction and ball milled for 20 minutes to obtain a mixed metal powder with a particle size of 300 mesh. The aluminum-containing heat-resistant stainless steel was polished with sandpaper, washed with ethanol and deionized water, dried, and then heated to 280°C for preheating. Under argon protection, the mixed metal powder was clad on the surface of the aluminum-containing heat-resistant stainless steel. During the cladding process, the laser power was 2KW, the spot diameter was 2mm, the scanning speed was 10mm / s, the powder feeding speed was 20g / min, and the argon flow rate was 18L / min. After the cladding was completed, the temperature was raised to 600°C and kept warm for 4h. After the insulation was completed, it was cooled to obtain high-temperature wear-resistant stainless steel.

[0060] Step 3: Chromium nitrate was added to deionized water, and the temperature was raised to 90°C with continuous stirring to fully dissolve the chromium nitrate to obtain a 0.04 g / mL chromium nitrate solution. The pH of the chromium nitrate solution was then adjusted to 5 with aqueous ammonia. The solution was stirred for 24 hours and then allowed to stand for 12 hours to obtain a chromium oxide sol.

[0061] Step 4: Aluminum isopropoxide was added to deionized water and stirred for 2 h to obtain an aluminum isopropoxide solution with a concentration of 0.08 g / mL. The pH was then adjusted to 3 with concentrated nitric acid. The mixture was stirred in a sealed container for 1.5 h and then allowed to stand in a water bath at 70-80°C for 12 h to obtain an alumina sol.

[0062] Step 5: Add ethyl orthosilicate to anhydrous ethanol, stir for 1 hour, then heat to 70°C and add deionized water to obtain a 0.5 g / mL ethyl orthosilicate ethanol aqueous solution (the volume ratio of ethanol to deionized water is 2:1). Adjust the pH to 3 with concentrated nitric acid, continue stirring for 2 hours, and let stand at room temperature for 6 hours to obtain a silica sol.

[0063] Step 6: Immerse the high-temperature wear-resistant stainless steel in chromium oxide sol for 60 seconds. After ensuring that the sol completely covers the high-temperature wear-resistant stainless steel, slowly extract the high-temperature wear-resistant stainless steel at a rate of 5 cm / min, dry it at room temperature for 30 minutes, heat it to 90°C and continue drying for 30 minutes, then immerse it in alumina sol and silica sol respectively, treat the high-temperature wear-resistant stainless steel in the same way, finally, place it in a heating furnace, heat it to 600°C at a rate of 10°C / min and keep it warm for 2 hours to obtain high-temperature oxidation-resistant wear-resistant stainless steel;

[0064] Step 7: Add 20 parts of aluminum dihydrogen phosphate to 50 parts of deionized water by mass and stir evenly to obtain an aluminum dihydrogen phosphate solution. Add 0.5% by mass of polydimethylsiloxane defoamer and 1% by mass of phosphate dispersant to the aluminum dihydrogen phosphate solution and stir evenly. Then, add 30 parts of mullite whiskers, 16 parts of silicon nitride and 12 parts of molybdenum sulfide and ultrasonically disperse for 30 minutes to obtain a self-lubricating phosphate ceramic coating. Spray the self-lubricating phosphate ceramic coating on the surface of high-temperature resistant, oxidation-resistant and wear-resistant stainless steel. After drying at 70°C, heat to 300°C and sinter for 4 hours. After sintering, cool to room temperature to obtain high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders.

[0065] Based on Example 1, control experiments were conducted, specifically Comparative Example 1, Comparative Example 2, and Comparative Example 3, as described below:

[0066] Comparative Example 1: This comparative example relates to a method for preparing high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders. The difference from Example 1 is that no aluminum or iron is added to the heat-resistant stainless steel. Specifically:

[0067] Step 1: After heating the stainless steel to 1700°C and melting it, add ferromolybdenum, ferrocobalt and ferrotungsten for smelting. After the ferromolybdenum, ferrocobalt and ferrotungsten are melted, add 1% of the mass of the heat-resistant stainless steel as a calcium aluminate deslagging agent for deslagging. 15 minutes before the molten steel is discharged from the furnace, add ferrovanadium and ferrotitanium for smelting. After the ferroaluminum, ferrovanadium and ferrotitanium are melted, add 1% of the mass of the heat-resistant stainless steel as a calcium aluminate deslagging agent for deslagging. 5 minutes before the molten steel is discharged from the furnace, add 0.5% of the mass of the heat-resistant stainless steel as a silicon aluminum calcium barium deoxidizer for deoxidation. The molten steel is discharged from the furnace at 1680°C and poured into a ladle. Ferrocereium, ferroboron and 0.5% of the mass of the heat-resistant stainless steel as a silicon aluminum calcium barium deoxidizer are added to the molten steel in the ladle. After standing for 5 minutes, the molten steel is cast at 1600°C under argon protection to obtain heat-resistant stainless steel.

[0068] In the heat-resistant stainless steel prepared in step 1, the mass fractions of each element are: C: 0.075%, Si: 0.38%, Mn: 0.86%, Cr: 19.25%, Ni: 8.35%, Mo: 0.17%, W: 0.37%, Co: 0.15%, V: 0.17%, Ti: 0.22%, B: 0.007%, Ce: 0.01%, P: 0.03%, S: 0.025%, and the balance is iron;

[0069] Step 2: By mass fraction, 68.8% nickel powder, 20% chromium powder, 6% aluminum powder, 4% vanadium titanium powder, 1% copper powder, and 0.2% zirconium powder were mixed and ball-milled for 20 minutes to obtain a mixed metal powder with a particle size of 300 mesh. The heat-resistant stainless steel was polished with sandpaper, washed with ethanol and deionized water, dried, and then heated to 280°C for preheating. Under argon protection, the mixed metal powder was clad on the surface of the heat-resistant stainless steel. During the cladding process, the laser power was 2KW, the spot diameter was 2mm, the scanning speed was 10mm / s, the powder feeding speed was 20g / min, and the argon flow rate was 18L / min. After the cladding was completed, the temperature was raised to 600°C and kept warm for 4h. After the insulation was completed, it was cooled to obtain high-temperature wear-resistant stainless steel;

[0070] Step 3: Chromium nitrate was added to deionized water, and the temperature was raised to 90°C with continuous stirring to fully dissolve the chromium nitrate to obtain a 0.04 g / mL chromium nitrate solution. The pH of the chromium nitrate solution was then adjusted to 5 with aqueous ammonia. The solution was stirred for 24 hours and then allowed to stand for 12 hours to obtain a chromium oxide sol.

[0071] Step 4: Aluminum isopropoxide was added to deionized water and stirred for 2 h to obtain an aluminum isopropoxide solution with a concentration of 0.08 g / mL. The pH was then adjusted to 3 with concentrated nitric acid. The mixture was stirred in a sealed container for 1.5 h and then allowed to stand in a water bath at 70-80°C for 12 h to obtain an alumina sol.

[0072] Step 5: Add ethyl orthosilicate to anhydrous ethanol, stir for 1 hour, then heat to 70°C and add deionized water to obtain a 0.5 g / mL ethyl orthosilicate ethanol aqueous solution (the volume ratio of ethanol to deionized water is 2:1). Adjust the pH to 3 with concentrated nitric acid, continue stirring for 2 hours, and let stand at room temperature for 6 hours to obtain a silica sol.

[0073] Step 6: Immerse the high-temperature wear-resistant stainless steel in chromium oxide sol for 60 seconds. After ensuring that the sol completely covers the high-temperature wear-resistant stainless steel, slowly extract the high-temperature wear-resistant stainless steel at a rate of 5 cm / min, dry it at room temperature for 30 minutes, heat it to 90°C and continue drying for 30 minutes, then immerse it in alumina sol and silica sol respectively, treat the high-temperature wear-resistant stainless steel in the same way, finally, place it in a heating furnace, heat it to 600°C at a rate of 10°C / min and keep it warm for 2 hours to obtain high-temperature oxidation-resistant wear-resistant stainless steel;

[0074] Step 7: Add 15 parts of aluminum dihydrogen phosphate to 50 parts of deionized water by mass and stir evenly to obtain an aluminum dihydrogen phosphate solution. Add 0.5% by mass of polydimethylsiloxane defoamer and 1% by mass of phosphate dispersant to the aluminum dihydrogen phosphate solution and stir evenly. Then, add 25 parts of mullite whiskers, 12 parts of silicon nitride and 8 parts of molybdenum sulfide and ultrasonically disperse for 30 minutes to obtain a self-lubricating phosphate ceramic coating. Spray the self-lubricating phosphate ceramic coating on the surface of high-temperature resistant, oxidation-resistant and wear-resistant stainless steel. After drying at 70°C, heat to 300°C and sinter for 4 hours. After sintering, cool to room temperature to obtain high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders.

[0075] Comparative Example 2: This comparative example relates to a method for preparing high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders. The difference from Example 1 is that the mixed metal powder contains only nickel powder and chromium powder, specifically:

[0076] Step 1: After heating the stainless steel to 1700°C and melting it, add ferromolybdenum, ferrocobalt and ferrottungsten for smelting. After the ferromolybdenum, ferrocobalt and ferrottungsten are melted, add a calcium aluminate deslagging agent containing 1% of the mass of the aluminum heat-resistant stainless steel for deslagging. 15 minutes before the molten steel is discharged from the furnace, add ferroaluminum, ferrovanadium and ferrotitanium for smelting. After the ferroaluminum, ferrovanadium and ferrotitanium are melted, add a calcium aluminate deslagging agent containing 1% of the mass of the aluminum heat-resistant stainless steel for deslagging. 5 minutes before the molten steel is discharged from the furnace, add a silicon aluminum calcium barium deoxidizer containing 0.5% of the mass of the aluminum heat-resistant stainless steel for deoxidation. The molten steel is discharged from the furnace at 1680°C and poured into a ladle. Ferrocere, ferroboron and a silicon aluminum calcium barium deoxidizer containing 0.5% of the mass of the aluminum heat-resistant stainless steel are added to the molten steel in the ladle. After standing for 5 minutes, the molten steel is cast at 1600°C under argon protection to obtain aluminum heat-resistant stainless steel.

[0077] In the aluminum-containing heat-resistant stainless steel prepared in step 1, the mass fractions of each element are: C: 0.075%, Si: 0.38%, Mn: 0.86%, Cr: 19.25%, Ni: 8.35%, Mo: 0.17%, W: 0.37%, Co: 0.15%, Al: 2.0%, V: 0.17%, Ti: 0.22%, B: 0.007%, Ce: 0.01%, P: 0.03%, S: 0.025%, and the balance is iron;

[0078] Step 2: 80% nickel powder and 20% chromium powder were mixed by mass fraction and ball milled for 20 minutes to obtain a mixed metal powder with a particle size of 300 mesh. The aluminum-containing heat-resistant stainless steel was polished with sandpaper, washed with ethanol and deionized water, dried, and heated to 280°C for preheating. Under argon protection, the mixed metal powder was clad on the surface of the aluminum-containing heat-resistant stainless steel. During the cladding process, the laser power was 2KW, the spot diameter was 2mm, the scanning speed was 10mm / s, the powder feeding speed was 20g / min, and the argon flow rate was 18L / min. After the cladding was completed, the temperature was raised to 600°C and kept warm for 4h. After the insulation was completed, it was cooled to obtain high-temperature wear-resistant stainless steel.

[0079] Step 3: Chromium nitrate was added to deionized water, and the temperature was raised to 90°C with continuous stirring to fully dissolve the chromium nitrate to obtain a 0.04 g / mL chromium nitrate solution. The pH of the chromium nitrate solution was then adjusted to 5 with aqueous ammonia. The solution was stirred for 24 hours and then allowed to stand for 12 hours to obtain a chromium oxide sol.

[0080] Step 4: Aluminum isopropoxide was added to deionized water and stirred for 2 h to obtain an aluminum isopropoxide solution with a concentration of 0.08 g / mL. The pH was then adjusted to 3 with concentrated nitric acid. The mixture was stirred in a sealed container for 1.5 h and then allowed to stand in a water bath at 70-80°C for 12 h to obtain an alumina sol.

[0081] Step 5: Add ethyl orthosilicate to anhydrous ethanol, stir for 1 hour, then heat to 70°C and add deionized water to obtain a 0.5 g / mL ethyl orthosilicate ethanol aqueous solution (the volume ratio of ethanol to deionized water is 2:1). Adjust the pH to 3 with concentrated nitric acid, continue stirring for 2 hours, and let stand at room temperature for 6 hours to obtain a silica sol.

[0082] Step 6: Immerse the high-temperature wear-resistant stainless steel in chromium oxide sol for 60 seconds. After ensuring that the sol completely covers the high-temperature wear-resistant stainless steel, slowly extract the high-temperature wear-resistant stainless steel at a rate of 5 cm / min, dry it at room temperature for 30 minutes, heat it to 90°C and continue drying for 30 minutes, then immerse it in alumina sol and silica sol respectively, treat the high-temperature wear-resistant stainless steel in the same way, finally, place it in a heating furnace, heat it to 600°C at a rate of 10°C / min and keep it warm for 2 hours to obtain high-temperature oxidation-resistant wear-resistant stainless steel;

[0083] Step 7: Add 15 parts of aluminum dihydrogen phosphate to 50 parts of deionized water by mass and stir evenly to obtain an aluminum dihydrogen phosphate solution. Add 0.5% by mass of polydimethylsiloxane defoamer and 1% by mass of phosphate dispersant to the aluminum dihydrogen phosphate solution and stir evenly. Then, add 25 parts of mullite whiskers, 12 parts of silicon nitride and 8 parts of molybdenum sulfide and ultrasonically disperse for 30 minutes to obtain a self-lubricating phosphate ceramic coating. Spray the self-lubricating phosphate ceramic coating on the surface of high-temperature resistant, oxidation-resistant and wear-resistant stainless steel. After drying at 70°C, heat to 300°C and sinter for 4 hours. After sintering, cool to room temperature to obtain high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders.

[0084] Comparative Example 3: This comparative example relates to a method for preparing high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders. The difference from Example 1 is that the phosphate ceramic coating does not contain mullite whiskers and molybdenum sulfide. Specifically:

[0085] Step 1: After heating the stainless steel to 1700°C and melting it, add ferromolybdenum, ferrocobalt and ferrottungsten for smelting. After the ferromolybdenum, ferrocobalt and ferrottungsten are melted, add a calcium aluminate deslagging agent containing 1% of the mass of the aluminum heat-resistant stainless steel for deslagging. 15 minutes before the molten steel is discharged from the furnace, add ferroaluminum, ferrovanadium and ferrotitanium for smelting. After the ferroaluminum, ferrovanadium and ferrotitanium are melted, add a calcium aluminate deslagging agent containing 1% of the mass of the aluminum heat-resistant stainless steel for deslagging. 5 minutes before the molten steel is discharged from the furnace, add a silicon aluminum calcium barium deoxidizer containing 0.5% of the mass of the aluminum heat-resistant stainless steel for deoxidation. The molten steel is discharged from the furnace at 1680°C and poured into a ladle. Ferrocere, ferroboron and a silicon aluminum calcium barium deoxidizer containing 0.5% of the mass of the aluminum heat-resistant stainless steel are added to the molten steel in the ladle. After standing for 5 minutes, the molten steel is cast at 1600°C under argon protection to obtain aluminum heat-resistant stainless steel.

[0086] In the aluminum-containing heat-resistant stainless steel prepared in step 1, the mass fractions of each element are: C: 0.075%, Si: 0.38%, Mn: 0.86%, Cr: 19.25%, Ni: 8.35%, Mo: 0.17%, W: 0.37%, Co: 0.15%, Al: 2.0%, V: 0.17%, Ti: 0.22%, B: 0.007%, Ce: 0.01%, P: 0.03%, S: 0.025%, and the balance is iron;

[0087] Step 2: By mass fraction, 68.8% nickel powder, 20% chromium powder, 6% aluminum powder, 4% vanadium titanium powder, 1% copper powder, and 0.2% zirconium powder were mixed and ball-milled for 20 minutes to obtain a mixed metal powder with a particle size of 300 mesh. The aluminum-containing heat-resistant stainless steel was polished with sandpaper, washed with ethanol and deionized water, dried, and then heated to 280°C for preheating. Under argon protection, the mixed metal powder was clad on the surface of the aluminum-containing heat-resistant stainless steel. During the cladding process, the laser power was 2KW, the spot diameter was 2mm, the scanning speed was 10mm / s, the powder feeding speed was 20g / min, and the argon flow rate was 18L / min. After the cladding was completed, the temperature was raised to 600°C and kept warm for 4h. After the insulation was completed, it was cooled to obtain high-temperature wear-resistant stainless steel;

[0088] Step 3: Chromium nitrate was added to deionized water, and the temperature was raised to 90°C with continuous stirring to fully dissolve the chromium nitrate to obtain a 0.04 g / mL chromium nitrate solution. The pH of the chromium nitrate solution was then adjusted to 5 with aqueous ammonia. The solution was stirred for 24 hours and then allowed to stand for 12 hours to obtain a chromium oxide sol.

[0089] Step 4: Aluminum isopropoxide was added to deionized water and stirred for 2 h to obtain an aluminum isopropoxide solution with a concentration of 0.08 g / mL. The pH was then adjusted to 3 with concentrated nitric acid. The mixture was stirred in a sealed container for 1.5 h and then allowed to stand in a water bath at 70-80°C for 12 h to obtain an alumina sol.

[0090] Step 5: Add ethyl orthosilicate to anhydrous ethanol, stir for 1 hour, then heat to 70°C and add deionized water to obtain a 0.5 g / mL ethyl orthosilicate ethanol aqueous solution (the volume ratio of ethanol to deionized water is 2:1). Adjust the pH to 3 with concentrated nitric acid, continue stirring for 2 hours, and let stand at room temperature for 6 hours to obtain a silica sol.

[0091] Step 6: Immerse the high-temperature wear-resistant stainless steel in chromium oxide sol for 60 seconds. After ensuring that the sol completely covers the high-temperature wear-resistant stainless steel, slowly extract the high-temperature wear-resistant stainless steel at a rate of 5 cm / min, dry it at room temperature for 30 minutes, heat it to 90°C and continue drying for 30 minutes, then immerse it in alumina sol and silica sol respectively, treat the high-temperature wear-resistant stainless steel in the same way, finally, place it in a heating furnace, heat it to 600°C at a rate of 10°C / min and keep it warm for 2 hours to obtain high-temperature oxidation-resistant wear-resistant stainless steel;

[0092] Step 7: Add 15 parts of aluminum dihydrogen phosphate to 50 parts of deionized water by mass, stir evenly to obtain an aluminum dihydrogen phosphate solution, add 0.5% by mass of polydimethylsiloxane defoamer and 1% by mass of phosphate dispersant to the aluminum dihydrogen phosphate solution, stir evenly, add 12 parts of silicon nitride, and ultrasonically disperse for 30 minutes to obtain a phosphate ceramic coating. Spray the phosphate ceramic coating on the surface of high-temperature resistant, oxidation-resistant and wear-resistant stainless steel, dry at 70°C, then heat to 300°C and sinter for 4 hours. After sintering, cool to room temperature to obtain high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders.

[0093] Detection experiment:

[0094] The high-temperature resistant and wear-resistant stainless steel samples for pneumatic cylinders required for the test were prepared according to the preparation methods in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3, respectively, and microhardness tests, wear resistance tests, and high-temperature oxidation tests were carried out.

[0095] Microhardness test: An HSV-1000 digital microhardness tester (Sivaka Precision) was used to test the microhardness of the samples. First, the stainless steel samples were cut with a wire cutting machine to obtain test specimens of 50 mm × 10 mm × 2 mm. The test specimens were washed with ethanol and deionized water and wiped dry with a cloth. The test specimens were then fixed with the fixture of the hardness tester. The Knupp indenter was placed on the test area of ​​the specimen surface and pressed tightly. The instrument was then started and a load of 100 gf was applied for 10 seconds to measure the microhardness of the specimens. Five points were selected on each specimen for testing, and the test results were averaged.

[0096] Wear resistance test: The wear resistance of the sample was tested using an HSR-2M reciprocating friction and wear tester (Zhongke Kaihua). First, the stainless steel sample was cut with a wire cutting machine to obtain a 50mm×50mm×2mm test specimen. The test specimen was washed with ethanol and deionized water, wiped dry with a cloth, and fixed with the fixture of the test machine after weighing the mass. The coated side of the sample was used to grind against the grinding material. The grinding material was a GCr15 high-carbon chromium bearing steel ball with a diameter of 4mm. The load was 500g, the sliding stroke was 5mm, the friction time was 15min, and the ambient temperature was 25℃. After the friction, it was washed again with ethanol and deionized water, wiped dry with a cloth, and the mass after wear was weighed to calculate the wear amount of the sample. Another set of test specimens was taken in the same way, and the temperature was raised to 800℃ after weighing the mass. At 800℃, with other conditions being the same, the wear amount of the sample under high temperature was tested.

[0097] High-temperature oxidation test: A ZRT-1200 thermogravimetric analyzer (Beijing Instrument High-Tech) was used to test the high-temperature oxidation resistance of the sample. First, the stainless steel sample was cut with a wire cutting machine to obtain a test specimen of 7 mm × 9 mm × 2 mm. The sample was then washed with ethanol and deionized water, wiped dry with a cloth, and weighed. The test specimen was hung on the hook of the thermogravimetric analyzer with a platinum wire. The temperature was raised to 1000°C at a heating rate of 20°C and kept warm for 5 hours. After the insulation period, the sample was naturally cooled to room temperature. The test specimen was removed and weighed again, and the thermogravimetric change of the sample was calculated. Each sample was tested three times at the same time, and the test results were averaged.

[0098]

[0099] Conclusion: It can be seen from the test data that the microhardness, wear loss, wear loss at high temperature, and thermogravimetric change caused by high-temperature oxidation of the stainless steel samples for pneumatic cylinders prepared in each embodiment are better than those of the comparative examples. The wear-resistant stainless steel for pneumatic cylinders provided by the present invention has good hardness, wear resistance, high-temperature wear resistance, and high-temperature oxidation resistance.

[0100] 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 and wear-resistant stainless steel for pneumatic cylinders, characterized by: Specifically: Step 1: Use stainless steel, ferromolybdenum, ferrocobalt, ferrotungsten, ferroaluminum, ferrovanadium, ferrotitanium, ferrocerium and ferroboron as raw materials to smelt aluminum-containing heat-resistant stainless steel; Step 2: Using laser cladding technology, the mixed metal powder is laser clad on the surface of the aluminum-containing heat-resistant stainless steel to form a high-temperature wear-resistant alloy layer to obtain high-temperature wear-resistant stainless steel; Step 3: immersing the high-temperature wear-resistant stainless steel in chromium oxide sol, aluminum oxide sol, and silicon oxide sol in sequence to form a multi-layer high-temperature oxidation film on the surface of the high-temperature wear-resistant stainless steel to obtain high-temperature oxidation-resistant wear-resistant stainless steel; Step 4: Add aluminum dihydrogen phosphate to deionized water and stir evenly to obtain an aluminum dihydrogen phosphate solution. Add polydimethylsiloxane defoamer and phosphate dispersant to the aluminum dihydrogen phosphate solution and stir evenly. Then, add mullite whiskers, silicon nitride and molybdenum sulfide and ultrasonically disperse for 20-30 minutes to obtain a self-lubricating phosphate ceramic coating. Step 5: Spray self-lubricating phosphate ceramic coating on the surface of high-temperature resistant, oxidation-resistant and wear-resistant stainless steel, dry at 60-70°C, then heat to 300-350°C and sinter for 3-4 hours. After sintering, cool to room temperature to obtain high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders; In step 2, the mixed metal powder includes, by mass fraction, 18-22% chromium powder, 4-8% aluminum powder, 2-4% vanadium titanium powder, 1-3% copper powder, 0.1-0.5% zirconium powder, and the balance is nickel powder; The mass fractions of each element in aluminum-containing heat-resistant stainless steel are: C: 0.06~0.08%, Si: 0.3~0.5%, Mn: 0.8~1.0%, Cr: 19~21%, Ni: 8.0~10.0%, Mo: 0.15~0.2%, W: 0.35~0.45%, Co: 0.14~0.20%, Al: 2.0~2.5%, V: 0.15~0.20%, Ti: 0.2~0.3%, B: 0.005~0.01%, Ce≤0.04%, P≤0.04%, S≤0.05%, and the balance is iron.

2. The method for preparing high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders according to claim 1, characterized in that: Step 1 is as follows: The stainless steel is heated to 1680-1700°C for melting, and then ferromolybdenum, ferrocobalt and ferrotungsten are added for smelting. After the ferromolybdenum, ferrocobalt and ferrotungsten are melted, a slag remover is added for slag removal. 15-20 minutes before the molten steel is discharged from the furnace, ferroaluminum, ferrovanadium and ferrotitanium are added for smelting. After the ferroaluminum, ferrovanadium and ferrotitanium are melted, a slag remover is added for slag removal. 5-8 minutes before the molten steel is discharged from the furnace, a deoxidizer is added for deoxidation. The molten steel is discharged from the furnace at 1650-1680°C and poured into a ladle. Ferrocereium, ferroboron and a deoxidizer are added to the molten steel in the ladle. After standing for 5-8 minutes, the molten steel is cast at 1580-1600°C under argon protection to obtain aluminum-containing heat-resistant stainless steel.

3. The method for preparing high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders according to claim 2, characterized in that: The slag remover is calcium aluminate deslagging agent, and the amount of the deslagging agent added each time is 1-1.5% of the mass of the aluminum-containing heat-resistant stainless steel; the deoxidizer is one of silicon aluminum calcium barium deoxidizer and silicon calcium manganese deoxidizer, and the amount of the deoxidizer added each time is 0.1-0.5% of the mass of the aluminum-containing heat-resistant stainless steel.

4. The method for preparing high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders according to claim 1, characterized in that: Step 2 is as follows: Nickel powder, chromium powder, aluminum powder, vanadium titanium powder, copper powder and zirconium powder are mixed and ball milled for 10-20 minutes to obtain mixed metal powder with a particle size of 280-300 mesh. The aluminum-containing heat-resistant stainless steel is polished with sandpaper, washed with ethanol and deionized water, dried and heated to 250-280°C for preheating. Under argon protection, the mixed metal powder is clad on the surface of the aluminum-containing heat-resistant stainless steel. During the cladding process, the laser power is 2-2.2KW, the spot diameter is 1-3mm, the scanning speed is 10-13mm / s, the powder feeding speed is 20-25g / min, and the argon flow rate is 15-20L / min. After the cladding is completed, the temperature is raised to 600-640°C and kept warm for 2-4h. After the insulation is completed, it is cooled to obtain high-temperature wear-resistant stainless steel.

5. The method for preparing high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders according to claim 1, characterized in that: Step 3 is as follows: Chromium nitrate is added to deionized water, heated to 80-90°C and stirred continuously to fully dissolve the chromium nitrate, and then the pH of the chromium nitrate solution is adjusted to 5-6 with aqueous ammonia, and the mixture is stirred for 20-24 hours and allowed to stand for 6-12 hours to obtain a chromium oxide sol with a chromium nitrate concentration of 0.03-0.05 g / mL; Aluminum isopropoxide was added to deionized water, stirred for 2-4 hours, and then the pH was adjusted to 2-3 with concentrated nitric acid. After stirring for 1-1.5 hours in a sealed container, the mixture was allowed to stand for 8-12 hours in a water bath heated at 70-80°C to obtain an alumina sol with an aluminum isopropoxide concentration of 0.08-0.1 g / mL. Add ethyl orthosilicate to anhydrous ethanol, stir for 0.5-1 hour, then heat to 60-70°C and add deionized water. Adjust the pH to 2-3 with concentrated nitric acid, continue stirring for 1-2 hours, and let stand at room temperature for 4-6 hours to obtain a silica sol with an ethyl orthosilicate concentration of 0.4-0.6 g / mL; Immerse the high-temperature wear-resistant stainless steel in chromium oxide sol for 60-90 seconds. After ensuring that the sol completely covers the high-temperature wear-resistant stainless steel, slowly extract the high-temperature wear-resistant stainless steel at a rate of 5-10 cm / min, dry it at room temperature for 20-30 minutes, then heat it to 90-100°C and continue drying it for 20-30 minutes. Then immerse it in alumina sol and silica sol respectively, and treat the high-temperature wear-resistant stainless steel in the same way. Finally, place it in a heating furnace, heat it to 600-620°C at a rate of 10-15°C / min and keep it warm for 1-2 hours to obtain high-temperature oxidation-resistant wear-resistant stainless steel.

6. The method for preparing high-temperature resistant and wear-resistant stainless steel for pneumatic cylinders according to claim 1, characterized in that: The mass ratio of aluminum dihydrogen phosphate, mullite whiskers, silicon nitride, and molybdenum sulfide is (15-20):(25-30):(12-16):(8-12); the mass fraction of the polydimethylsiloxane defoamer in the self-lubricating phosphate ceramic coating is 0.2-0.5%, and the mass fraction of the phosphate ester dispersant is 0.5-2%.

7. A high-temperature resistant and wear-resistant stainless steel for a pneumatic cylinder, manufactured by the preparation method according to any one of claims 1 to 6.

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