A polishing liquid and a polishing method for stainless steel vacuum vessels

Abstract

The present application relates to the technical field of polishing liquid, in particular to a polishing liquid and polishing method for stainless steel vacuum vessels, which comprises the following raw materials by mass: 0.5-3% of soluble sulfate, 0.1-2% of soluble silicate, 0.5-1% of soluble phosphate and 0.21-3% of auxiliary materials, and the rest is water, wherein the auxiliary materials are used to reduce the precipitation of crystalline salt and improve the polishing effect. The purpose is to inhibit the point corrosion by using sulfate, and make the polishing surface more uniform; to increase the smoothness of the polishing surface by using silicate; to promote the polishing speed by using phosphate, so that the cooperation of the three can achieve mirror effect during polishing, and the polishing time is short; and the cooperation of the auxiliary materials with sulfate, phosphate and silicate can reduce the combination of acid radical ions and metal ions in the polishing liquid, thereby reducing the precipitation of acid salt crystallization, prolonging the service life of the polishing liquid, and improving the polishing effect.

Description

Technical Field

[0001] This invention relates to the field of polishing fluid technology, and more particularly to a polishing fluid and polishing method for stainless steel vacuum vessels. Background Technology

[0002] Currently, common polishing processes include mechanical polishing, chemical polishing, electrochemical polishing, and plasma nanopolishing, each with its own advantages and disadvantages. Among these, plasma nanopolishing is a novel metal surface treatment process: the plasma reacts only at the molecular layer of the workpiece surface. The atomic spacing within the molecules is typically 0.1-0.3 nanometers, and the treatment depth is 0.3-1.5 nanometers. The surface roughness of the polished object is within 1 mm. Therefore, plasma nanopolishing can chemically activate the workpiece surface, remove the surface molecular contaminant layer, and cross-link the surface chemical substances. Plasma, also known as the fourth state of matter, is an electromagnetic gaseous discharge phenomenon that partially ionizes gaseous particles. This ionized gas includes atoms, molecules, atomic groups, ions, and electrons. Plasma is produced under high temperature and pressure, where the polishing agent is water-soluble. Under these conditions, electrons detach from the atomic nucleus, forming positively charged ions. When these ions reach a certain quantity, they constitute the plasma state. Plasma has high energy, and when these plasmas rub against the object to be polished, they can achieve a bright surface effect in a very short time.

[0003] Existing plasma polishing agents are primarily based on sulfate-organic acid systems. During the polishing of stainless steel, the iron, chromium, and nickel elements contained in the stainless steel are continuously converted into metal ions and dissolved into the polishing solution. As the polishing process progresses, the concentration of these metal ions increases, combining with sulfate ions to form sulfate precipitates. On the one hand, this reduces the sulfate concentration, affecting the service life; on the other hand, the precipitation of sulfate crystals affects the current path, impacting the polishing effect. Summary of the Invention

[0004] In view of this, one objective of the present invention is to provide a polishing solution for stainless steel vacuum vessels, which reduces the combination of acid radicals and metal ions during polishing, thereby reducing the precipitation of acid salt crystals, extending the service life of the polishing solution, and improving the polishing effect; another objective is to provide a polishing method for stainless steel vacuum vessels.

[0005] The present invention solves the above-mentioned technical problems through the following technical means:

[0006] A polishing solution for stainless steel vacuum vessels comprises the following raw materials in parts by weight: 0.5-3% soluble sulfate, 0.1-2% soluble silicate, 0.5-1% soluble phosphate, and 0.21-3% auxiliary materials, with the remainder being water. The auxiliary materials are used to reduce the precipitation of crystalline salts and improve the polishing effect.

[0007] Based on the above technical means, the use of sulfates can inhibit pitting corrosion and make the polished surface more uniform; the use of silicates can increase the smoothness of the polished surface; and the use of phosphates can promote the polishing speed. Thus, the combination of these three can achieve a mirror effect during polishing with a short polishing time. Furthermore, the combination of auxiliary materials with sulfates, phosphates, and silicates can reduce the combination of acid radicals and metal ions in the polishing solution, thereby reducing the precipitation of acid salt crystals, extending the service life of the polishing solution, and improving the polishing effect.

[0008] Preferably, the soluble sulfate is one or more combinations of sodium sulfate, ammonium sulfate, potassium sulfate, and sodium thiosulfate.

[0009] Further preferred, the soluble sulfate is sodium sulfate with a concentration of 10–22 g / L.

[0010] Preferably, the soluble silicate is one or a combination of sodium silicate, potassium silicate, and ammonium silicate.

[0011] Further preferred, the soluble silicate is sodium silicate with a concentration of 6–13 g / L.

[0012] Preferably, the soluble phosphate is one or more combinations of potassium phosphate, sodium phosphate, ammonium phosphate, potassium dihydrogen phosphate, and potassium hydrogen phosphate.

[0013] Further preferred, the soluble phosphate is potassium phosphate, with a concentration of 2–8 g / L.

[0014] Preferably, the excipients are one or more combinations of glycerin, polyacrylamide, sodium gluconate and modified diatomaceous earth.

[0015] More preferably, the excipient is a mixture of glycerol and modified diatomaceous earth, with a mass ratio of glycerol to modified diatomaceous earth of (1-3):(0.3-1).

[0016] Based on the aforementioned technical methods, by selecting glycerol as an auxiliary material, glycerol does not electrolyze or react during plasma polishing and can prevent the generation of acid mist. During plasma gas layer polishing, it reduces the volatilization of acid radicals combined with hydrogen ions in the polishing solution, thereby increasing the concentration of acid radical ions in the polishing solution and extending its service life. Furthermore, glycerol forms a complex with phosphate ions, which can inhibit the corrosion of surface bumps on stainless steel vacuum vessels during polishing, preventing over-corrosion.

[0017] Modified diatomaceous earth has a core-shell structure with diatomaceous earth as the core and polyacrylic acid as the shell. The core-shell structure has several channels, which can effectively adsorb metal ions during the polishing process, reduce the concentration of metal ions in the polishing solution, and reduce the chance of acid radicals combining with metal ions.

[0018] Preferably, the method for preparing the modified diatomaceous earth includes the following steps:

[0019] S1. Disperse diatomaceous earth in water to form a suspension, add polyacrylic acid, stir evenly, then gradually add sodium aluminate and ammonium chloride, stirring to form a gel;

[0020] S2. Crystallize the gel obtained in step S1 for 48-72 hours. After crystallization, break it down to a particle size of 5-20 mm.

[0021] S3. Place the crystals crushed in step S2 into a polyacrylamide solution, let stand overnight, filter, add paraffin liquid, ultrasonically disperse, cool, and granulate to obtain modified diatomaceous earth.

[0022] According to the above-mentioned technical means, diatomaceous earth is formed into a suspension, and then polyacrylic acid is added and dissolved in the suspension and thoroughly mixed with diatomaceous earth. Then, sodium aluminate and ammonium chloride are gradually added to form a gel coating diatomaceous earth. The gel is then crystallized to fix the gel structure. During the crystallization process, ammonium chloride is decomposed by heat, and ammonia gas is volatilized, forming several channels on the crystallized gel. The broken gel crystals are then placed in a polyacrylamide aqueous solution, allowing the polyacrylamide aqueous solution to enter the channels of the gel crystals. Finally, the polyacrylamide aqueous solution is coated inside the gel crystals by wax sealing, thereby obtaining core-shell structured modified diatomaceous earth.

[0023] When modified diatomaceous earth is used in polishing solution, as the temperature of the polishing solution rises to 75-85℃, the wax seal gradually disappears, allowing the polyacrylamide aqueous solution in the modified diatomaceous earth to come into contact with the polishing solution during the polishing process. This causes the metal ions in the polishing solution to flocculate and adsorb. Furthermore, due to the particle size of the modified diatomaceous earth, it does not volatilize. During the polishing process of the stainless steel vacuum vessel surface by the plasma gas layer, the continuous generation of the gas layer ensures that the modified diatomaceous earth particles do not obstruct the polishing of the stainless steel vacuum vessel surface by the plasma gas layer.

[0024] Preferably, in step S2, the crystallization conditions are: vertical rotation at 90-110°C and a rotation speed of 5-30 r / min.

[0025] According to the above-mentioned technical means, controlling the crystallization temperature during the crystallization process is beneficial to controlling the formation of channels on the crystal, and vertical rotation is beneficial to improving the uniformity of crystallization and the uniformity of channel distribution.

[0026] This application also discloses a polishing method for stainless steel vacuum vessels, which uses the polishing liquid described above and further includes the following steps:

[0027] S10. To prepare the polishing solution, add soluble sulfate, soluble silicate, and soluble phosphate to water, stir until homogeneous, then add the auxiliary materials and continue stirring until homogeneous to obtain the plasma polishing solution.

[0028] S20. Place the plasma polishing solution in the polishing tank, place the clamped stainless steel vacuum vessel in the polishing solution and immerse it completely, and use the stainless steel vacuum vessel as the polishing anode.

[0029] S30. Plasma polishing is performed on the inner wall of a stainless steel vacuum vessel using direct current. The voltage of the polishing tank is a positive pulse voltage of 220-380V, the voltage frequency is 10K-30KHz, and the current density is 30-60A / dm³. 2 The polishing time is 30s-120s to complete the polishing of the inner wall of the stainless steel vacuum vessel;

[0030] S40. After the inner wall polishing is completed, switch the cathode electrode and apply direct current to perform plasma polishing on the outer wall of the stainless steel vacuum vessel again. The voltage of the polishing tank is a positive pulse voltage of 220-250V, the voltage frequency is 20K-40KHz, and the current density is 45-80A / dm³. 2 The polishing time is 30s-120s to complete the polishing of the outer wall of the stainless steel vacuum vessel;

[0031] S50. Remove the polished stainless steel vacuum vessel, clean and dry it to obtain the polished stainless steel vacuum vessel.

[0032] According to the above technical means, by immersing the stainless steel vacuum vessel in the polishing liquid and using the central cathode method to polish the inner wall of the stainless steel vacuum vessel, a stable gas layer can be formed on the inner wall of the stainless steel vacuum vessel during polishing, thereby quickly polishing the inner wall of the stainless steel vacuum vessel. At this time, although a gas layer will also be formed on the outer wall of the stainless steel vacuum vessel due to the use of the central cathode method, it is mainly due to the stainless steel vacuum vessel as the anode and the combined action of the hot polishing liquid at 75-85℃. This gas layer is relatively thin and does not produce a polishing effect.

[0033] After the inner wall of the stainless steel vacuum vessel is polished, the cathode electrode is switched, with the polishing tank as the cathode and the stainless steel vacuum vessel as the anode. At this point, the outer wall of the stainless steel vacuum vessel is polished. During this process, due to electromagnetic shielding, although an air layer is generated on the inner wall of the stainless steel vacuum vessel, it does not polish the inner wall. Although acid ions in the polishing solution will come into contact with the inner wall and easily cause pitting corrosion, the possibility of pitting corrosion can be reduced by controlling the pH of the polishing solution and treating the cathode rod, thus obtaining a mirror-like finish on both the inner and outer walls of the stainless steel vacuum vessel.

[0034] Furthermore, when polishing the outer wall of a stainless steel vacuum vessel, the thickness of the gas layer is reduced by decreasing the voltage intensity and increasing the current density and voltage frequency. The thinner gas layer increases the possibility of local contact between the outer wall and the polishing liquid. Once the outer wall comes into contact with the polishing liquid, a local short circuit will be formed, generating a large amount of heat in a very short time. This causes the surface protrusions at this location to be removed quickly. In addition, due to the reduced voltage, the gas layer on the inner wall will also form a barrier, reducing the possibility of acid radical ions contacting the inner wall. Combined with electromagnetic shielding, this further reduces the possibility of pitting corrosion.

[0035] Preferably, in step S20, the polishing cathode is a cathode rod, and a stainless steel vacuum vessel is fitted over the cathode rod; in step S40, the polishing cathode is a polishing tank, and the cathode is switched by a switch.

[0036] Based on the above technical means, the cathode can be changed from a cathode rod to a polishing tank by using a conversion switch, which is simple and convenient.

[0037] Preferably, in step S40, after the cathode conversion, a modified diatomaceous earth sleeve is fitted onto the cathode rod.

[0038] Based on the above technical means, by installing a modified diatomaceous earth sleeve on the cathode rod, when the cathode rod is not used as a cathode, the diatomaceous earth sleeve is no longer filled with polyacrylamide or sealed with wax. This allows the pores on the modified diatomaceous earth to form an adsorption effect on the polishing liquid under the action of the circulation system, enhancing the adsorption of acid radical ions. Combined with the effect of sulfate, this reduces pitting corrosion on the inner wall.

[0039] The present application, employing the above-described scheme, has the following beneficial effects:

[0040] 1. By using sulfates, silicates, phosphates, glycerol and modified diatomaceous earth as polishing solutions, the combination of acid radicals and metal ions in the polishing solution can be reduced, thereby reducing the precipitation of acid salt crystals, extending the service life of the polishing solution, and improving the polishing effect.

[0041] 2. When using modified diatomaceous earth, a core-shell structure is formed with diatomaceous earth as the core and polyacrylic acid as the shell. The core-shell structure has several channels, which can effectively adsorb metal ions during the polishing process, reduce the concentration of metal ions in the polishing liquid, reduce the chance of acid radicals combining with metal ions, and flocculate and adsorb metal ions in the polishing liquid during use. At the same time, it will not block the plasma gas layer from polishing the surface of stainless steel vacuum vessels.

[0042] 3. During the polishing process, the inner wall of the stainless steel vacuum vessel is polished first using the central cathode method, and then the outer wall of the stainless steel vacuum vessel is polished through cathode conversion. This allows both the inner and outer walls of the stainless steel vacuum vessel to be polished in one operation, thus improving polishing efficiency. Detailed Implementation

[0043] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification:

[0044] This application discloses a polishing solution for stainless steel vacuum vessels, comprising the following raw materials in parts by weight: 0.5-3% soluble sodium sulfate, with a concentration of 10-22 g / L; 0.1-2% soluble sodium silicate, with a concentration of 6-13 g / L; 0.5-1% soluble potassium phosphate, with a concentration of 2-8 g / L; and 0.21-3% a mixture of glycerol and modified diatomaceous earth as excipients, with the remainder being water. The concentration of the active ingredient in the polishing solution is 4.2-5.0%, and the pH is 6.5-7.0.

[0045] Example 1: Polishing Method for Stainless Steel Vacuum Vessels

[0046] Preparation of modified diatomaceous earth

[0047] S1. Take 5 parts by weight of diatomaceous earth (D 50 =30-45um) dispersed in water to form a suspension, 9.5 parts by weight of polyacrylic acid were added and stirred evenly, and then 2.7 parts by weight of sodium aluminate and 1.3 parts by weight of ammonium chloride were gradually added and stirred to form a gel;

[0048] S2. The gel obtained in step S1 is vertically rotated at 90-110℃ at a speed of 10-15 r / min for 48 h. After crystallization, it is cooled to room temperature and then crushed to a particle size of 10 mm.

[0049] S3. Place the crystals crushed in step S2 into an aqueous solution of polyacrylamide, let stand overnight, filter, add to paraffin liquid, ultrasonically disperse at a power of 100-200W for 10-30 minutes, cool, and obtain modified diatomaceous earth.

[0050] S4. After granulating the paraffin liquid in step S3, cool it to obtain granular modified diatomaceous earth with a particle size of 11-12 mm.

[0051] S5. The gel from step S1 is formed into a sleeve shape and then crystallized to obtain diatomaceous earth coated with polyacrylic acid.

[0052] Polishing of stainless steel vacuum vessels

[0053] S10. Prepare the polishing solution by adding sodium sulfate, sodium silicate, and potassium phosphate to water and stirring until homogeneous. Then add glycerol and granular modified diatomaceous earth. The sodium sulfate content is 2% with a concentration of 19±1 g / L, the sodium silicate content is 1.0% with a concentration of 10±1 g / L, the potassium phosphate content is 0.5% with a concentration of 5±1 g / L, the glycerol content is 1.0%, and the modified diatomaceous earth content is 0.5%. Continue stirring until homogeneous to obtain the plasma polishing solution.

[0054] S20. Place the plasma polishing liquid in the polishing tank, place the clamped stainless steel vacuum vessel in the polishing liquid and immerse it completely, use the stainless steel vacuum vessel as the polishing anode, use the cathode rod in the polishing tank as the polishing cathode, and put the stainless steel vacuum vessel over the cathode rod.

[0055] S30. Plasma polishing is performed on the inner wall of a stainless steel vacuum vessel using direct current. The voltage of the polishing tank is a positive pulse voltage of 220-380V, the voltage frequency is 10K-30KHz, and the current density is 30-60A / dm³. 2 The polishing time is 30s-120s to complete the polishing of the inner wall of the stainless steel vacuum vessel;

[0056] S40. After the inner wall polishing is completed, the cathode electrode is switched using a selector switch, and the polishing tank is used as the polishing cathode. At this time, the modified diatomaceous earth sleeve is attached to the cathode rod, and DC current is applied to perform plasma polishing on the outer wall of the stainless steel vacuum vessel again. The voltage of the polishing tank is a positive pulse voltage of 220-250V, the voltage frequency is 20K-40KHz, and the current density is 45-80A / dm³. 2 The polishing time is 30s-90s to complete the polishing of the outer wall of the stainless steel vacuum vessel;

[0057] S50. Remove the polished stainless steel vacuum vessel, clean and dry it to obtain the polished stainless steel vacuum vessel.

[0058] Example 2: Polishing Method Two for Stainless Steel Vacuum Vessels

[0059] Preparation of modified diatomaceous earth

[0060] S1. Take 5 parts by weight of diatomaceous earth (D 50 =30-45um) dispersed in water to form a suspension, 9.5 parts by weight of polyacrylic acid were added and stirred evenly, and then 2.7 parts by weight of sodium aluminate and 1.3 parts by weight of ammonium chloride were gradually added and stirred to form a gel;

[0061] S2. The gel obtained in step S1 is vertically rotated at 90-110℃ at a speed of 10-15 r / min for 72 h. After crystallization, it is cooled to room temperature and then crushed to a particle size of 10 mm.

[0062] S3. Place the crystals crushed in step S2 into an aqueous solution of polyacrylamide, let stand overnight, filter, add to paraffin liquid, ultrasonically disperse at a power of 100-200W for 10-30 minutes, cool, and obtain modified diatomaceous earth.

[0063] S4. After granulating the paraffin liquid in step S3, cool it to obtain granular modified diatomaceous earth with a particle size of 11-12 mm.

[0064] S5. The gel from step S1 is formed into a sleeve shape and then crystallized to obtain diatomaceous earth coated with polyacrylic acid.

[0065] Polishing of stainless steel vacuum vessels

[0066] S10. Prepare the polishing solution by adding sodium sulfate, sodium silicate, and potassium phosphate to water and stirring until homogeneous. Then add glycerol and granular modified diatomaceous earth. The sodium sulfate content is 1.8% with a concentration of 17±1 g / L, the sodium silicate content is 0.6% with a concentration of 7±1 g / L, the potassium phosphate content is 0.6% with a concentration of 6±1 g / L, the glycerol content is 0.8%, and the modified diatomaceous earth content is 0.7%. Continue stirring until homogeneous to obtain the plasma polishing solution.

[0067] S20. Place the plasma polishing liquid in the polishing tank, place the clamped stainless steel vacuum vessel in the polishing liquid and immerse it completely, use the stainless steel vacuum vessel as the polishing anode, use the cathode rod in the polishing tank as the polishing cathode, and put the stainless steel vacuum vessel over the cathode rod.

[0068] S30. Plasma polishing is performed on the inner wall of a stainless steel vacuum vessel using direct current. The voltage of the polishing tank is a positive pulse voltage of 220-380V, the voltage frequency is 10K-30KHz, and the current density is 30-60A / dm³. 2 The polishing time is 30s-120s to complete the polishing of the inner wall of the stainless steel vacuum vessel;

[0069] S40. After the inner wall polishing is completed, the cathode electrode is switched using a selector switch, and the polishing tank is used as the polishing cathode. At this time, the modified diatomaceous earth sleeve is attached to the cathode rod, and DC current is applied to perform plasma polishing on the outer wall of the stainless steel vacuum vessel again. The voltage of the polishing tank is a positive pulse voltage of 220-250V, the voltage frequency is 20K-40KHz, and the current density is 45-80A / dm³. 2 The polishing time is 30s-90s to complete the polishing of the outer wall of the stainless steel vacuum vessel;

[0070] S50. Remove the polished stainless steel vacuum vessel, clean and dry it to obtain the polished stainless steel vacuum vessel.

[0071] Example 3: Polishing Method Three for Stainless Steel Vacuum Vessels

[0072] Preparation of modified diatomaceous earth

[0073] S1. Take 5 parts by weight of diatomaceous earth (D 50 =30-45um) dispersed in water to form a suspension, 9.5 parts by weight of polyacrylic acid were added and stirred evenly, and then 2.7 parts by weight of sodium aluminate and 1.3 parts by weight of ammonium chloride were gradually added and stirred to form a gel;

[0074] S2. The gel obtained in step S1 is vertically rotated at 90-110℃ at a speed of 10-15 r / min for 72 h. After crystallization, it is cooled to room temperature and then crushed to a particle size of 10 mm.

[0075] S3. Place the crystals crushed in step S2 into an aqueous solution of polyacrylamide, let stand overnight, filter, add to paraffin liquid, ultrasonically disperse at a power of 100-200W for 10-30 minutes, cool, and obtain modified diatomaceous earth.

[0076] S4. After granulating the paraffin liquid in step S3, cool it to obtain granular modified diatomaceous earth with a particle size of 11-12 mm.

[0077] S5. The gel from step S1 is formed into a sleeve shape and then crystallized to obtain diatomaceous earth coated with polyacrylic acid.

[0078] Polishing of stainless steel vacuum vessels

[0079] S10. Prepare the polishing solution by adding sodium sulfate, sodium silicate, and potassium phosphate to water and stirring until homogeneous. Then add glycerol and granular modified diatomaceous earth. The sodium sulfate content is 2.2% with a concentration of 21±1 g / L, the sodium silicate content is 0.6% with a concentration of 7±1 g / L, the potassium phosphate content is 0.2% with a concentration of 3±1 g / L, the glycerol content is 1.0%, and the modified diatomaceous earth content is 1.0%. Continue stirring until homogeneous to obtain the plasma polishing solution.

[0080] S20. Place the plasma polishing liquid in the polishing tank, place the clamped stainless steel vacuum vessel in the polishing liquid and immerse it completely, use the stainless steel vacuum vessel as the polishing anode, use the cathode rod in the polishing tank as the polishing cathode, and put the stainless steel vacuum vessel over the cathode rod.

[0081] S30. Plasma polishing is performed on the inner wall of a stainless steel vacuum vessel using direct current. The voltage of the polishing tank is a positive pulse voltage of 220-380V, the voltage frequency is 10K-30KHz, and the current density is 30-60A / dm³. 2 The polishing time is 30s-120s to complete the polishing of the inner wall of the stainless steel vacuum vessel;

[0082] S40. After the inner wall polishing is completed, the cathode electrode is switched using a selector switch, and the polishing tank is used as the polishing cathode. At this time, the modified diatomaceous earth sleeve is attached to the cathode rod, and DC current is applied to perform plasma polishing on the outer wall of the stainless steel vacuum vessel again. The voltage of the polishing tank is a positive pulse voltage of 220-250V, the voltage frequency is 20K-40KHz, and the current density is 45-80A / dm³. 2 The polishing time is 30s-90s to complete the polishing of the outer wall of the stainless steel vacuum vessel;

[0083] S50. Remove the polished stainless steel vacuum vessel, clean and dry it to obtain the polished stainless steel vacuum vessel.

[0084] Example 4 (Comparative Example 1): Polishing Method Four for Stainless Steel Vacuum Vessels

[0085] In this embodiment, modified diatomaceous earth is not used, and only glycerin is used as an auxiliary material. The amount of other raw materials used in the polishing liquid is the same as in Example 3.

[0086] Polishing of stainless steel vacuum vessels

[0087] S10. Prepare the polishing solution by adding sodium sulfate, sodium silicate, and potassium phosphate to water and stirring until homogeneous. Then add glycerin, wherein the content of sodium sulfate is 2.2%, the content of sodium silicate is 0.6%, the content of potassium phosphate is 0.2%, and the content of glycerin is 0.3%. Stir until homogeneous to obtain the plasma polishing solution.

[0088] S20. Place the plasma polishing liquid in the polishing tank, place the clamped stainless steel vacuum vessel in the polishing liquid and immerse it completely, use the stainless steel vacuum vessel as the polishing anode, use the cathode rod in the polishing tank as the polishing cathode, and put the stainless steel vacuum vessel over the cathode rod.

[0089] S30. Plasma polishing is performed on the inner wall of a stainless steel vacuum vessel using direct current. The voltage of the polishing tank is a positive pulse voltage of 220-380V, the voltage frequency is 10K-30KHz, and the current density is 30-60A / dm³. 2 The polishing time is 30s-120s to complete the polishing of the inner wall of the stainless steel vacuum vessel;

[0090] S40. After the inner wall polishing is completed, the cathode electrode is switched using a selector switch, and the polishing tank is used as the polishing cathode. At this time, the modified diatomaceous earth sleeve is attached to the cathode rod, and DC current is applied to perform plasma polishing on the outer wall of the stainless steel vacuum vessel again. The voltage of the polishing tank is a positive pulse voltage of 220-250V, the voltage frequency is 20K-40KHz, and the current density is 45-80A / dm³. 2 The polishing time is 30s-90s to complete the polishing of the outer wall of the stainless steel vacuum vessel;

[0091] S50. Remove the polished stainless steel vacuum vessel, clean and dry it to obtain the polished stainless steel vacuum vessel.

[0092] Example 5 (Comparative Example 2): Polishing Method Five for Stainless Steel Vacuum Vessels

[0093] In this embodiment, only glycerin is used as the excipient, and the amount of the remaining raw materials in the polishing liquid is the same as in Example 3; conventional plasma polishing is used during polishing.

[0094] Polishing of stainless steel vacuum vessels

[0095] S10. Prepare the polishing solution by adding sodium sulfate, sodium silicate, and potassium phosphate to water and stirring until homogeneous. Then add glycerin, wherein the content of sodium sulfate is 2.2%, the content of sodium silicate is 0.6%, the content of potassium phosphate is 0.2%, and the content of glycerin is 0.3%. Stir until homogeneous to obtain the plasma polishing solution.

[0096] S20. Place the plasma polishing liquid in the polishing tank, place the clamped stainless steel vacuum vessel in the polishing liquid and immerse it completely, use the stainless steel vacuum vessel as the polishing anode and the polishing tank as the polishing cathode.

[0097] S30. Plasma polishing is performed on the inner wall of a stainless steel vacuum vessel using direct current. The voltage of the polishing tank is a positive pulse voltage of 220-380V, the voltage frequency is 10K-30KHz, and the current density is 30-60A / dm³. 2Polishing time is 30s-120s to complete the polishing of stainless steel vacuum vessels;

[0098] S40. Remove the polished stainless steel vacuum vessel, clean and dry it to obtain the polished stainless steel vacuum vessel.

[0099] Example 6 (Comparative Example 3): Polishing Method Six for Stainless Steel Vacuum Vessels

[0100] In this embodiment, an ammonium salt formulation is used, and the polishing solution contains 2% ammonium sulfate, 0.8% ammonium phosphate, 1% sodium sulfate, and 1.4% sodium silicate.

[0101] Polishing of stainless steel vacuum vessels

[0102] S10. Prepare the polishing solution by mixing 2% ammonium sulfate, 0.8% ammonium phosphate, 1% sodium sulfate, and 1.4% sodium silicate until homogeneous to obtain a plasma polishing solution;

[0103] S20. Place the plasma polishing liquid in the polishing tank, place the clamped stainless steel vacuum vessel in the polishing liquid and immerse it completely, use the stainless steel vacuum vessel as the polishing anode, use the cathode rod in the polishing tank as the polishing cathode, and put the stainless steel vacuum vessel over the cathode rod.

[0104] S30. Plasma polishing is performed on the inner wall of a stainless steel vacuum vessel using direct current. The voltage of the polishing tank is a positive pulse voltage of 220-380V, the voltage frequency is 10K-30KHz, and the current density is 30-60A / dm³. 2 The polishing time is 30s-120s to complete the polishing of the inner wall of the stainless steel vacuum vessel;

[0105] S40. After the inner wall polishing is completed, the cathode electrode is switched using a selector switch, and the polishing tank is used as the polishing cathode. At this time, the modified diatomaceous earth sleeve is attached to the cathode rod, and DC current is applied to perform plasma polishing on the outer wall of the stainless steel vacuum vessel again. The voltage of the polishing tank is a positive pulse voltage of 220-250V, the voltage frequency is 20K-40KHz, and the current density is 45-80A / dm³. 2 The polishing time is 30s-90s to complete the polishing of the outer wall of the stainless steel vacuum vessel;

[0106] S50. Remove the polished stainless steel vacuum vessel, clean and dry it to obtain the polished stainless steel vacuum vessel.

[0107] Example 7, Performance Testing

[0108] 1. Surface roughness

[0109] The surface roughness of the stainless steel vacuum vessels of Examples 1-3 and Comparative Examples 1-3 was tested according to GB / T3505-2000 using a handheld roughness tester. The test results are shown in Table 1. Wherein: Ra refers to the arithmetic mean deviation of the profile, which is the arithmetic mean of the absolute values ​​of the profile deviations within the sampling length; RSm refers to the average width of the profile unit, which is the average spacing of the micro-irregularities of the profile within the sampling length; the smaller Ra and the larger RSm, the better the surface smoothness.

[0110] 2. Surface reflectivity

[0111] The surface reflectance of the stainless steel vacuum vessels of Examples 1-3 and Comparative Examples 1-3 was tested according to GB2680-1994. The surface reflectance was measured using a surface reflectance meter, and the test results are shown in Table 1.

[0112] 3. Gloss

[0113] The gloss of the inner and outer surfaces of the stainless steel vacuum vessels of Examples 1-3 and Comparative Examples 1-3 was measured using a gloss meter. The test results are shown in Table 1.

[0114]

[0115]

[0116] As can be seen from the data in Table 1, in Examples 1-3 of this application, by using the composition of the polishing liquid and polishing the inner wall of the stainless steel vacuum vessel first and then polishing the outer wall of the stainless steel vacuum vessel, the surface defects of the inner and outer walls of the stainless steel vacuum vessel can be effectively removed, making the inner and outer walls of the stainless steel vacuum vessel smooth, bright, and with a mirror effect.

[0117] Comparing the data from Examples 1-3 with Comparative Example 1, it can be seen that the present application, through the combination of sulfate, silicate, phosphate, glycerol and modified diatomaceous earth, and by first polishing the inner wall of the stainless steel vacuum vessel using the central cathode method and then polishing the outer wall of the stainless steel vacuum vessel, can effectively reduce the surface roughness of the inner and outer walls of the stainless steel vacuum vessel and improve the surface reflectivity and gloss.

[0118] Comparing the data from Examples 1-3 with Comparative Example 2, it can be seen that the method of polishing the inner wall of the stainless steel vacuum vessel by using the central cathode method and then polishing the outer wall of the stainless steel vacuum vessel can greatly improve the surface roughness, surface reflectivity and gloss of the stainless steel vacuum vessel. Moreover, the use of the central cathode method can polish the inner wall of the stainless steel vacuum vessel, which is better than the traditional method.

[0119] Comparing the data from Examples 1-3 with Comparative Example 3, it can be seen that the polishing liquid formulation used in this application has a better polishing effect on the inner and outer walls of stainless steel vacuum vessels compared to the ammonium salt formulation.

[0120] The number of times the polishing slurries prepared in Examples 1-3 were used was tested, and the results are shown in Table 2 below.

[0121] Number of times used 508 523 530 450 450 420

[0122] The data above shows that the polishing slurry formulations used in Examples 1-3 of this application can extend the service life of the polishing slurry.

[0123] A comparison of the data from Examples 1-3 with Comparative Examples 1-2 shows that using modified diatomaceous earth in the polishing slurry can increase the number of uses of the polishing slurry. A comparison of the data from Examples 1-3 with Comparative Example 3 shows that the polishing slurry of this application has a longer service life compared to ammonium salt polishing slurries, and can reduce the cost of using the polishing slurry.

[0124] The polishing liquid and polishing method for stainless steel vacuum vessels provided by the present invention have been described in detail above. The specific embodiments are provided only to help understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0125] It should be noted that: for experimental steps or conditions not specified in the examples, the procedures and conditions described in conventional experimental procedures in the literature of this art can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0126] The above examples are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by anyone under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

Claims

1. A polishing liquid for stainless steel vacuum vessels, characterized in that, The raw materials include the following parts by weight: 0.5-3% soluble sulfate, 0.1-2% soluble silicate, 0.5-1% soluble phosphate, and 0.21-3% auxiliary materials, with the remainder being water. The auxiliary materials are used to reduce the precipitation of crystalline salts and improve the polishing effect. The auxiliary materials are a mixture of glycerol and modified diatomaceous earth. The preparation method of the modified diatomaceous earth includes the following steps: S1. Disperse diatomaceous earth in water to form a suspension, add polyacrylic acid, stir evenly, then gradually add sodium aluminate and ammonium chloride, stirring to form a gel; S2. Crystallize the gel obtained in step S1 for 48-72 hours. After crystallization, break it down to a particle size of 5-20 mm. S3. Place the crystals crushed in step S2 into a polyacrylamide solution, let stand overnight, filter, add paraffin liquid, ultrasonically disperse, cool, and granulate to obtain modified diatomaceous earth.

2. The polishing slurry according to claim 1, characterized in that, The soluble sulfate is one or more combinations of sodium sulfate, ammonium sulfate, potassium sulfate, and sodium thiosulfate.

3. The polishing slurry according to claim 1, characterized in that, The soluble silicate is one or more combinations of sodium silicate, potassium silicate, and ammonium silicate.

4. The polishing slurry according to claim 1, characterized in that, The soluble phosphate is one or more combinations of potassium phosphate, sodium phosphate, ammonium phosphate, potassium dihydrogen phosphate, and potassium hydrogen phosphate.

5. The polishing slurry according to claim 4, characterized in that, In step S2, the crystallization conditions are: vertical rotation at 90-110℃ and a rotation speed of 5-30 r / min.

6. A polishing method for stainless steel vacuum vessels, characterized in that, The polishing solution according to any one of claims 1-5 further includes the following steps: S10. To prepare the polishing solution, add soluble sulfate, soluble silicate, and soluble phosphate to water, stir until homogeneous, then add the auxiliary materials and continue stirring until homogeneous to obtain the plasma polishing solution. S20. Placing the plasma polishing solution in the polishing tank, placing the clamped stainless steel vacuum vessel in the polishing solution and immersing it completely, using the stainless steel vacuum vessel as the polishing anode, and the polishing tank having a circulation system for circulating the polishing solution. S30. Plasma polishing is performed on the inner wall of a stainless steel vacuum vessel using direct current. The voltage of the polishing tank is a positive pulse voltage of 220-380V, the voltage frequency is 10K-30KHz, and the current density is 30-60A / dm³. 2 The polishing time is 30s-120s to complete the polishing of the inner wall of the stainless steel vacuum vessel; S40. After the inner wall polishing is completed, the cathode electrode is switched, and direct current is applied again to perform plasma polishing on the outer wall of the stainless steel vacuum vessel. The voltage of the polishing tank is a positive pulse voltage of 220-250V, the voltage frequency is 20K-40KHz, and the current density is 45-80A / dm³. 2 The polishing time is 30s-120s to complete the polishing of the outer wall of the stainless steel vacuum vessel; S50. Remove the polished stainless steel vacuum vessel, clean and dry it to obtain the polished stainless steel vacuum vessel.

7. The polishing method according to claim 6, characterized in that, In step S20, the polishing cathode is a cathode rod, and a stainless steel vacuum vessel is fitted over the cathode rod; in step S40, the polishing cathode is a polishing tank, and the cathode is switched by a switch.

8. The polishing method according to claim 7, characterized in that, In step S40, after the cathode conversion, a modified diatomaceous earth sleeve is fitted onto the cathode rod.

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