Electropolishing of aluminum and aluminum alloys is widely used in production. If the polished parts are immediately oxidized for a short period of time, not only can the flat and bright appearance be formed, but also a complete oxide film can be formed, the corrosion resistance can be improved, and the surface gloss can be maintained for a long time.
Principle The principle of electropolishing is now a lot of debates among people from all walks of life in the world. It is recognized by everyone as the theory of mucosa. The theory is mainly: the metal ion detached from the workpiece and the phosphoric acid in the polishing solution form a phosphate film adsorbed on the surface of the workpiece. The mucosa is thinner at the convex portion, the concave portion is thicker, and the current density is high due to the convex portion. The dissolution is fast, as the mucous membrane flows, the irregularities change, and the rough surface is gradually leveled.
Advantages (1) The color inside and outside is consistent, the gloss is long-lasting, and the recess that can not be thrown by mechanical polishing can be leveled.
(2) High production efficiency and low cost.
(3) Increase the corrosion resistance of the workpiece surface, which can be applied to all stainless steel "target=_blank> stainless steel.
Required conditions and equipment Power supply; Rectifier; Electrode rod; Cooling tube; Heater; Hanger; Lead plate; Electrolyzer; Exhaust device power supply
The power supply can be selected from two-phase 220V and three-phase 380V.
Rectifier
Electrolytic polishing is not too strict on the power supply waveform. A thyristor rectifier or a high frequency rectifier can be used.
Rectifier no-load voltage: 0-20v
Load voltage (operating voltage): 8-10v
The working voltage is lower than 6v, the polishing speed is slow, and the brightness is insufficient.
Rectifier current: Depending on the size of the customer's workpiece.
Electrolysis cell and supporting facilities (anode rod)
It can be welded with PVC hard sheet (polypropylene). Install three electrode rods on the groove, with a movable anode rod in the middle, connect the anode of the power supply (or the positive pole), and the cathode rods on both sides, connect the cathode of the power supply (negative pole).
Heating facility and cooling equipment
1 heating can use quartz heating tube, titanium heating tube.
2 Cooling optional coil, the coil can be heated to cool.
Fixture
Titanium is best used as a hanger because titanium is more resistant to corrosion and has a long life. Titanium ions have no effect on the bath. It is recommended not to use copper hangers, because copper ions will deposit a layer of copper with poor adhesion on the surface of stainless steel "target=_blank> stainless steel, which will affect the polishing quality. The exposed parts of copper can be baked with PVC glue. , scrape off the insulating film at the contact point.
Anion and anode material
The cathode material is made of lead plate, and the anode material is made of copper.
The anode is between 1:2 and 3.5 than the cathode.
The optimum distance between the cathode and the anode is 10-30 cm.
For the moment, electropolishing is mainly for the surface brightening of stainless steel "target=_blank> stainless steel workpieces. Stainless steel" target=_blank> stainless steel workpieces are divided into 200 series, 300 series, 400 series materials, each series of materials must be used Electrolytic polishing liquid. For example, stainless steel "target=_blank> stainless steel 200 series stainless steel" target=_blank> stainless steel, must use 200 series of formula, this formula can not adapt to 300 series or 400 series of stainless steel "target=_blank> stainless steel material. This has been A major problem in China, because some manufacturers' materials are combined workpieces, including 200 series stainless steel "target=_blank> stainless steel, and 300 or 400 series stainless steel" target=_blank> stainless steel. In December 2007, Weihai Yun Senior engineer Wang Lingshu of Qing Chemical Development Institute developed a stainless steel "target=_blank> stainless steel universal electrolyte. This electrolyte is suitable for all stainless steel "target=_blank> stainless steel. It combines all the advantages of the original electrolyte, the specific gravity of the electrolyte is 1.70, the brightness is the mirror brightness. At the same time, new advantages are also developed. This electrolyte increases the original brightness and reduces the current density by half. In the production operation, it can save 50% of the electricity cost. The service life is increased by 40%. This electrolyte has been leading technology in China.
Electropolishing process: degreasing--washing--rust removal--washing--electrolytic polishing--washing--neutralization--washing--passivation--packaging type The electropolishing liquid currently used in production mainly includes:
a polishing solution consisting of sulfuric acid, phosphoric acid and chromic anhydride;
a polishing solution consisting of sulfuric acid and citric acid;
A mixed polishing solution consisting of sulfuric acid, phosphoric acid, hydrofluoric acid, and glycerin or the like.
Electrochemical polishing of steel parts
(1) Influence of material types There are many types of steel materials, and different polishing liquids should be used for different steel materials.
(2) Effects of various factors Phosphoric acid is the main component of the polishing liquid. The phosphate formed by it adheres to the surface of the anode and plays an important role in the polishing process. Sulfuric acid can increase the polishing rate, but the content should not be too high to avoid corrosion. Chromic anhydride can improve the polishing effect and make the surface bright.
The current density has a great influence on the polishing quality. Different current densities should be used for different solutions. The current density is too low, and the leveling effect is poor. If it is too high, it will cause over-corrosion. Temperature has a certain effect on the quality of the polishing, but it is not the main factor.
(3) Operational precautions
1 The newly prepared solution should be energized in the case of a large cathode area (the cathode area is several times larger than the anode area) to reduce a part of the hexavalent chromium to trivalent chromium. If the trivalent chromium is excessively increased during use, the opposite is true, that is, in the case of a large anode and a small cathode.
2 Frequently measure the density of the solution, and add water or heat the concentrated solution in time. The contents of phosphoric acid, sulfuric acid and chromic anhydride and trivalent chromium in the solution should be analyzed and adjusted periodically.
3 During the use, the content of dissolved iron in the anode gradually increases, and when the content of iron (calculated as Fe2 03) reaches 7% to 8%, it is partially replaced, or the solution is completely replaced.
4 Preparation First, the phosphoric acid and sulfuric acid are mixed, the chromic anhydride is dissolved in water, and then the acid mixture is poured into a chromic anhydride aqueous solution and heated to 80 ° C. The gelatin is slowly added under constant stirring (the reaction is intense). After (after about 1 h) the solution became a uniform grass green.
Electropolishing of other metals
Electrolytic polishing of copper and its alloys, the use of phosphoric acid electrolytes is widely used. Electrolytic polishing of aluminum and aluminum alloys is carried out using a solution of phosphoric acid monosulfate-chromic acid.
Electropolishing of aluminum and aluminum alloys is widely used in production. If the polished parts are subjected to a short-time oxidation treatment, not only can a flat and bright appearance be obtained, but also a complete oxide film can be formed, corrosion resistance can be improved, and the surface gloss can be maintained for a long period of time.
For the preparation method of the solution, reference can be made to the relevant content of electropolishing of steel parts.
When the aluminum content in the solution exceeds 5%, the solution should be partially replaced or completely replaced.
When the chloride ion content exceeds 1%, the surface of the part is prone to speckle corrosion. The chloride ion content in the water used to prepare the solution should be less than 80 mg/L.
Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
Principle The principle of electropolishing is now a lot of debates among people from all walks of life in the world. It is recognized by everyone as the theory of mucosa. The theory is mainly: the metal ion detached from the workpiece and the phosphoric acid in the polishing solution form a phosphate film adsorbed on the surface of the workpiece. The mucosa is thinner at the convex portion, the concave portion is thicker, and the current density is high due to the convex portion. The dissolution is fast, as the mucous membrane flows, the irregularities change, and the rough surface is gradually leveled.
Advantages (1) The color inside and outside is consistent, the gloss is long-lasting, and the recess that can not be thrown by mechanical polishing can be leveled.
(2) High production efficiency and low cost.
(3) Increase the corrosion resistance of the workpiece surface, which can be applied to all stainless steel "target=_blank> stainless steel.
Required conditions and equipment Power supply; Rectifier; Electrode rod; Cooling tube; Heater; Hanger; Lead plate; Electrolyzer; Exhaust device power supply
The power supply can be selected from two-phase 220V and three-phase 380V.
Rectifier
Electrolytic polishing is not too strict on the power supply waveform. A thyristor rectifier or a high frequency rectifier can be used.
Rectifier no-load voltage: 0-20v
Load voltage (operating voltage): 8-10v
The working voltage is lower than 6v, the polishing speed is slow, and the brightness is insufficient.
Rectifier current: Depending on the size of the customer's workpiece.
Electrolysis cell and supporting facilities (anode rod)
It can be welded with PVC hard sheet (polypropylene). Install three electrode rods on the groove, with a movable anode rod in the middle, connect the anode of the power supply (or the positive pole), and the cathode rods on both sides, connect the cathode of the power supply (negative pole).
Heating facility and cooling equipment
1 heating can use quartz heating tube, titanium heating tube.
2 Cooling optional coil, the coil can be heated to cool.
Fixture
Titanium is best used as a hanger because titanium is more resistant to corrosion and has a long life. Titanium ions have no effect on the bath. It is recommended not to use copper hangers, because copper ions will deposit a layer of copper with poor adhesion on the surface of stainless steel "target=_blank> stainless steel, which will affect the polishing quality. The exposed parts of copper can be baked with PVC glue. , scrape off the insulating film at the contact point.
Anion and anode material
The cathode material is made of lead plate, and the anode material is made of copper.
The anode is between 1:2 and 3.5 than the cathode.
The optimum distance between the cathode and the anode is 10-30 cm.
For the moment, electropolishing is mainly for the surface brightening of stainless steel "target=_blank> stainless steel workpieces. Stainless steel" target=_blank> stainless steel workpieces are divided into 200 series, 300 series, 400 series materials, each series of materials must be used Electrolytic polishing liquid. For example, stainless steel "target=_blank> stainless steel 200 series stainless steel" target=_blank> stainless steel, must use 200 series of formula, this formula can not adapt to 300 series or 400 series of stainless steel "target=_blank> stainless steel material. This has been A major problem in China, because some manufacturers' materials are combined workpieces, including 200 series stainless steel "target=_blank> stainless steel, and 300 or 400 series stainless steel" target=_blank> stainless steel. In December 2007, Weihai Yun Senior engineer Wang Lingshu of Qing Chemical Development Institute developed a stainless steel "target=_blank> stainless steel universal electrolyte. This electrolyte is suitable for all stainless steel "target=_blank> stainless steel. It combines all the advantages of the original electrolyte, the specific gravity of the electrolyte is 1.70, the brightness is the mirror brightness. At the same time, new advantages are also developed. This electrolyte increases the original brightness and reduces the current density by half. In the production operation, it can save 50% of the electricity cost. The service life is increased by 40%. This electrolyte has been leading technology in China.
Electropolishing process: degreasing--washing--rust removal--washing--electrolytic polishing--washing--neutralization--washing--passivation--packaging type The electropolishing liquid currently used in production mainly includes:
a polishing solution consisting of sulfuric acid, phosphoric acid and chromic anhydride;
a polishing solution consisting of sulfuric acid and citric acid;
A mixed polishing solution consisting of sulfuric acid, phosphoric acid, hydrofluoric acid, and glycerin or the like.
Electrochemical polishing of steel parts
(1) Influence of material types There are many types of steel materials, and different polishing liquids should be used for different steel materials.
(2) Effects of various factors Phosphoric acid is the main component of the polishing liquid. The phosphate formed by it adheres to the surface of the anode and plays an important role in the polishing process. Sulfuric acid can increase the polishing rate, but the content should not be too high to avoid corrosion. Chromic anhydride can improve the polishing effect and make the surface bright.
The current density has a great influence on the polishing quality. Different current densities should be used for different solutions. The current density is too low, and the leveling effect is poor. If it is too high, it will cause over-corrosion. Temperature has a certain effect on the quality of the polishing, but it is not the main factor.
(3) Operational precautions
1 The newly prepared solution should be energized in the case of a large cathode area (the cathode area is several times larger than the anode area) to reduce a part of the hexavalent chromium to trivalent chromium. If the trivalent chromium is excessively increased during use, the opposite is true, that is, in the case of a large anode and a small cathode.
2 Frequently measure the density of the solution, and add water or heat the concentrated solution in time. The contents of phosphoric acid, sulfuric acid and chromic anhydride and trivalent chromium in the solution should be analyzed and adjusted periodically.
3 During the use, the content of dissolved iron in the anode gradually increases, and when the content of iron (calculated as Fe2 03) reaches 7% to 8%, it is partially replaced, or the solution is completely replaced.
4 Preparation First, the phosphoric acid and sulfuric acid are mixed, the chromic anhydride is dissolved in water, and then the acid mixture is poured into a chromic anhydride aqueous solution and heated to 80 ° C. The gelatin is slowly added under constant stirring (the reaction is intense). After (after about 1 h) the solution became a uniform grass green.
Electropolishing of other metals
Electrolytic polishing of copper and its alloys, the use of phosphoric acid electrolytes is widely used. Electrolytic polishing of aluminum and aluminum alloys is carried out using a solution of phosphoric acid monosulfate-chromic acid.
Electropolishing of aluminum and aluminum alloys is widely used in production. If the polished parts are subjected to a short-time oxidation treatment, not only can a flat and bright appearance be obtained, but also a complete oxide film can be formed, corrosion resistance can be improved, and the surface gloss can be maintained for a long period of time.
For the preparation method of the solution, reference can be made to the relevant content of electropolishing of steel parts.
When the aluminum content in the solution exceeds 5%, the solution should be partially replaced or completely replaced.
When the chloride ion content exceeds 1%, the surface of the part is prone to speckle corrosion. The chloride ion content in the water used to prepare the solution should be less than 80 mg/L.
Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
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