A laser-jet electrochemical hybrid polishing method

Abstract

The present invention discloses a laser-jet electrochemical hybrid polishing method, which mainly utilizes laser irradiation combined with electrified spraying of electrolyte to process the surface of stainless steel, so as to solve the problems of low flexibility, limited shape and size, insufficient precision in jet electrochemical polishing, and easy oxidation and blackening of samples during laser polishing in traditional electrochemical polishing. The main creativity of the present invention is embodied in that the laser-jet electrochemical hybrid polishing has great flexibility, can perform selective polishing on large-sized and special-shaped workpieces in daily environment, effectively reduce the roughness of the workpiece surface and improve the surface reflectivity, and will not produce oxidation and morphological defects on the substrate surface.

Description

Technical Field

[0001] The present invention discloses a laser-jet electrochemical hybrid polishing technology, which is used to process a substrate in a daily environment by laser irradiation mixed with a flexible jet, thereby improving surface reflectivity and reducing surface roughness, thereby effectively improving antibacterial properties and wear resistance. Background Art

[0002] Stainless steel is a common metal material, which is widely used in the fields of daily household use, military and aerospace. After stainless steel is produced, a post-processing method is often needed to improve its surface performance and service life. Polishing is a method of smoothing the surface of the substrate. It is widely used as a common post-processing method because it can effectively improve the various properties of the substrate surface and increase the stability of the post-processing coating. However, the objects to be polished often have complex shapes, and ordinary grinding and polishing are difficult to process their surfaces. Therefore, a flexible polishing method that is not limited by material size and shape and has a certain polishing accuracy and polishing efficiency is needed. For this reason, people have invented various non-contact polishing methods. Traditional immersion electrochemical polishing has become a widely used polishing technology because it solves the problems of accuracy, efficiency and complex shape processing. However, this technology cannot process workpieces of any size, and the electrolyte commonly used in electrochemical polishing is a strong acid that is not environmentally friendly. In addition, shot peening solves the problem of processing of any size, but its accuracy is low and it takes too long; sand blasting will cause certain pollution and will harm the health of the operator.

[0003] Laser polishing is a polishing method that has emerged in recent years with the widespread use of lasers. As a non-contact polishing method, it has high processing flexibility and can process workpieces of different shapes. When using lasers to complete milling, polishing, welding and other processes, the laser irradiated by the laser transfers heat energy to the surface of the substrate through non-contact means, and the controller precisely controls the required processing effect. When lasers are used for polishing, they often need to be completed in an argon atmosphere, because in an atmospheric environment, the substrate can easily react thermally with oxygen and nitrogen in the atmosphere, causing cracking and yellowing of the substrate surface. Therefore, although laser polishing has the advantage of flexibility, it is extremely demanding for practical applications, and the thermal effect usually brings thermal stress and weakens the polishing effect.

[0004] Jet electrochemical polishing is a polishing technology developed based on the "viscous film theory" of traditional immersion electrochemical polishing. Although the mechanism of selective material removal is the same, the solution flow rate and electrolyte renewal rate under jet conditions are different from those of immersion polishing, and the electric field distribution is also very different from that of immersion polishing. Therefore, in actual jet electromachining, the surface of the substrate will produce uneven polishing due to uneven electric field distribution and jet influence. Therefore, a non-contact polishing method is needed as an auxiliary to improve the polishing effect.

[0005] Traditional electrochemical polishing usually uses three-acid electrolytes (i.e., phosphoric acid, sulfuric acid, and triacid). Triacid electrolytes have become the main electrolytes for polishing in enterprises due to their strong applicability and good effects. However, this type of electrolyte itself has polluting properties and is not easy to handle. In addition, since acidic solutions can easily cause corrosion to working equipment such as water pipes and electrodes, this type of electrolyte is not suitable for jet electropolishing.

[0006] Jet electrochemical polishing first requires the use of an electrolyte that is non-corrosive and non-alkaline to ensure the life of the working equipment and the influence of the corrosion effect of the electrolyte on its electrochemical properties as an electrolyte itself. Salt aqueous solutions cannot form a sticky film and therefore cannot meet the conditions required for polishing in principle and can only be used for electrochemical drilling, etc.

[0007] In the past two years, a series of ionic electrolytes have attracted widespread attention due to their environmentally friendly properties. Among them, people have begun to study the immersion electrochemical polishing of stainless steel and titanium alloys using electrolytes of alcohol-salt systems. Common electrolytes include sodium chloride-ethylene glycol, choline chloride-ethylene glycol, choline chloride-acetaldehyde-glycine-urea-propylene glycol, etc. The present invention is based on such electrolytes and has found an electrolyte suitable for jet electrochemistry based on the principle. Its main components are sodium chloride, ethylene glycol, propylene glycol and ethanol. Sodium chloride is a salt with high current efficiency. In the study of sodium chloride, it was found that sodium chloride-based solutions can maintain high current efficiency even at low currents. Ethylene glycol is a solvent with high viscosity and good stability. It is widely used in alcohol-salt systems because of its stable electrical properties. Because the solution flow rate during the jet is too fast, the viscous film is difficult to maintain. An appropriate amount of propylene glycol is added to increase the viscosity of the solution and the stability of the jet flow when it is columnar. According to research, the viscous film is mainly a mixture of chloride ions and high-valent matrix ions. The solubility rate of these ions in ethanol is relatively large. Therefore, an appropriate amount of ethanol is added to improve the adverse effects of ion accumulation on jet electropolishing.

[0008] The electrolyte used in the present invention has the properties of no pollution and high efficiency, has the potential to replace acid solution polishing, and is also very suitable for application in laser-jet electrochemical hybrid polishing. Laser-jet electrochemical hybrid polishing uses a water pump to spray the liquid flow to the surface of the substrate. Under the action of appropriate voltage, the surface of the stainless steel substrate is polished due to the action of the current. The laser is used as an auxiliary to make up for the defects in the jet electrochemical polishing. The electrolyte as a solvent dissolves the removed substrate to form a viscous film with higher adhesion and high resistance. Since this viscous film is distributed differently in parts of the substrate with different roughness, it is often reflected as a thicker accumulation on the micro-concave surface than on the micro-convex surface. Therefore, the more convex part of the micro-surface has a lower resistance, a higher relative removal rate, and a faster removal speed. Under the action of this selective removal, the surface of the substrate becomes flat, showing low roughness and high reflectivity. The substrate under jet treatment has a lower surface roughness and higher reflectivity, and has the potential to be no less than immersion polishing.

[0009] For laser-jet electrochemical hybrid polishing, the electrolyte used in the present invention is unique. On the one hand, the use of viscous electrolyte makes the entire jet electrochemical polishing process more stable, which is mainly reflected in the fact that the viscous film generated in the electrochemical reaction can remain on the surface of the substrate under the impact of a certain pressure of the fluid, ensuring the conditions required for electrochemical polishing; on the other hand, the continuously generated viscous film hinders the contact between the substrate and the atmosphere, and oxidation, nitridation and the like will not occur under the direct action of the laser, so that the laser can be introduced into the process of jet electrochemical polishing to successfully improve the defects of single jet polishing; finally, the circulation of the liquid flow can also enhance the effect of selective polishing by regulating the temperature.

[0010] In the field of substrate polishing, polishing of materials with complex shapes can improve the surface properties and service life of the materials. Therefore, based on the principle of electrochemical polishing, the present invention proposes a jet electrochemical polishing method, which can polish the workpiece more flexibly and break through the shape and size restrictions. Summary of the invention

[0011] The purpose of the present invention is to provide a method for laser-jet electrochemical hybrid polishing. An environmentally friendly acid-free electrolyte is sprayed onto a substrate using a spray head and a water pump, and a laser coaxial with the spray head is used to irradiate the jet electric action area with laser, and the substrate is subjected to laser-jet electrochemical hybrid polishing (such as Figure 1 shown).

[0012] The technical solution of the present invention is as follows:

[0013] A laser-jet electrochemical hybrid polishing method, the method comprising:

[0014] (1) Clean and air-dry the surface of the stainless steel to be treated;

[0015] (2) The stainless steel pretreated in step (1) is clamped on a workbench as an anode, and the nozzle is used as a cathode. The nozzle is vertically aligned with the anode workpiece, the laser light outlet and the nozzle liquid outlet are kept coaxial and the relative distance between the two is adjusted to a fixed value, the water pump is started, and the electrolyte is sprayed toward the stainless steel workpiece through the nozzle. At the same time, the laser is turned on to irradiate the galvanic action area to perform laser-jet electrochemical hybrid polishing;

[0016] The electrolyte composition of the polishing is: NaCl 58.44 g / L, the solvent is a mixed solvent of ethanol, ethylene glycol and glycerol in a volume ratio of 2:8:1;

[0017] The electrical process parameters for polishing are: constant voltage mode, pulse power supply voltage is adjusted to 300-600V, pulse frequency is 50-600Hz, duty cycle is 20-60%; power supply is pulse power supply;

[0018] The laser process parameters for polishing are: the laser power is adjusted to 50-80W; the light source is a blue laser;

[0019] The processing time of laser-jet electrochemical hybrid polishing is 2-3 minutes; the flow rate of the electrolyte fluid is 1-2L / min, and the diameter of the liquid column is 4mm;

[0020] The cathode stainless steel liquid flow nozzle is a through cylinder with an inner diameter of 4mm and an outer diameter of 8mm. The inter-electrode distance between the nozzle and the workpiece is h = 8-30mm. Figure 2 As shown; the laser light outlet and the nozzle liquid outlet remain coaxial and the relative distance between the two is 234-254mm.

[0021] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0022] (1) The present invention is based on electrochemical polishing technology, and the ionic electrolyte used is relatively environmentally friendly.

[0023] (2) Compared with traditional immersion electrochemical polishing, the present invention breaks through the size limitation of traditional immersion polishing and can polish selected areas of any size. In addition, laser assistance is added, which greatly improves the polishing efficiency while being less affected by the negative effects of laser polishing.

[0024] (3) The electrolyte used in the present invention is more suitable for jet electrochemical polishing than traditional acidic electrolytes and ionic electrolytes that are currently widely studied. This electrolyte is unique for laser-jet electrochemical hybrid polishing. On the one hand, it stabilizes the jet electrochemical effect, and on the other hand, it reduces the adverse effects of the laser in the atmosphere.

[0025] (4) The roughness of the substrate after laser-jet electropolishing is significantly reduced, and it has better precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the laser-jet electrochemical hybrid polishing method.

[0027] Figure 2 Laser-jet mixing action area and principle diagram. DETAILED DESCRIPTION

[0028] The present invention is further described below by means of specific embodiments, but the protection scope of the present invention is not limited thereto.

[0029] The stainless steel workpiece material in the following embodiments is 304 stainless steel, and the sample size is 50×50×1 mm.

[0030] Example 1

[0031] 1) Pre-treat stainless steel, including cleaning and drying.

[0032] 2) Prepare electrolyte: the electrolyte composition is: NaCl 58.44g / L, the solvent is a mixed solvent of ethanol, ethylene glycol and glycerol, and the volume ratio of ethanol, ethylene glycol and glycerol is 2:8:1;

[0033] 3) Setting the jet electrochemical process: constant voltage mode, pulse power supply voltage is adjusted to 300 V, pulse frequency is 50 Hz, and duty cycle is 20%;

[0034] 4) Set the power of the blue laser to 50W;

[0035] 5) The workpiece was subjected to jet polishing for 2 min, the electrolyte flow rate was 1 L / min, the liquid column diameter was 4 mm, the inter-electrode distance between the jet nozzle and the workpiece was h = 10 mm; the laser light outlet and the nozzle liquid outlet were kept coaxial and the relative distance between the two was 234 nm.

[0036] The surface roughness after polishing was tested and it was found that the surface roughness was reduced from 614 nm to 194 nm.

[0037] Example 2

[0038] 1) Pre-treat stainless steel, including cleaning and drying.

[0039] 2) preparing an electrolyte: the electrolyte composition is: NaCl 58.44 g / L, the solvent is a mixed solvent of ethanol, ethylene glycol and glycerol, and the volume ratio of ethanol, ethylene glycol and glycerol is 3:9:2;

[0040] 3) Setting the jet electrochemical process: constant voltage mode, pulse power supply voltage adjusted to 400 V, pulse frequency to 100 Hz, duty cycle to 30%;

[0041] 4) Set the power of the blue laser to 60W;

[0042] 5) The workpiece was subjected to jet polishing for 2 min, the electrolyte flow rate was 1 L / min, the liquid column diameter was 4 mm, the inter-electrode distance between the jet nozzle and the workpiece was h = 10 mm; the laser light outlet and the nozzle liquid outlet were kept coaxial and the relative distance between the two was 234 nm.

[0043] The surface roughness after polishing was tested and it was found that the surface roughness was reduced from 623 nm to 181 nm.

[0044] Example 3

[0045] 1) Pre-treat stainless steel, including cleaning and drying.

[0046] 2) Prepare electrolyte: the electrolyte composition is: NaCl 58.44g / L, the solvent is a mixed solvent of ethanol, ethylene glycol and glycerol, and the volume ratio of ethanol, ethylene glycol and glycerol is 2:8:1;

[0047] 3) Setting the jet electrochemical process: constant voltage mode, pulse power supply voltage is adjusted to 600 V, pulse frequency is 200 Hz, and duty cycle is 40%;

[0048] 4) Set the power of the blue laser to 70W;

[0049] 5) The workpiece was subjected to jet polishing for 2 minutes, the electrolyte flow rate was 1 L / min, the liquid column diameter was 4 mm, the inter-electrode distance between the jet nozzle and the workpiece was h = 20 mm; the laser light outlet and the nozzle liquid outlet were kept coaxial and the relative distance between the two was 234 nm.

[0050] The surface roughness after polishing was tested and it was found that the surface roughness was reduced from 604nm to 155nm.

[0051] Example 4

[0052] 1) Pre-treat stainless steel, including cleaning and drying.

[0053] 2) Prepare electrolyte: the electrolyte composition is: NaCl 58.44g / L, the solvent is a mixed solvent of ethanol, ethylene glycol and glycerol, and the volume ratio of ethanol, ethylene glycol and glycerol is 2:8:1;

[0054] 3) Setting the jet electrochemical process: constant voltage mode, pulse power supply voltage is adjusted to 500 V, pulse frequency is 50 Hz, and duty cycle is 55%;

[0055] 4) Set the power of the blue laser to 80W;

[0056] 5) The workpiece was subjected to jet polishing for 2 minutes, the electrolyte flow rate was 1 L / min, the liquid column diameter was 4 mm, the inter-electrode distance between the jet nozzle and the workpiece was h = 30 mm; the laser light outlet and the nozzle liquid outlet were kept coaxial and the relative distance between the two was 254 nm.

[0057] The surface roughness after polishing was tested and it was found that the surface roughness was reduced from 586nm to 169nm.

[0058] Example 5

[0059] 1) Pre-treat stainless steel, including cleaning and drying.

[0060] 2) Prepare electrolyte: the electrolyte composition is: NaCl 58.44g / L, the solvent is a mixed solvent of ethanol, ethylene glycol and glycerol, and the volume ratio of ethanol, ethylene glycol and glycerol is 2:8:1;

[0061] 3) Setting the jet electrochemical process: constant voltage mode, pulse power supply voltage adjusted to 550 V, pulse frequency to 400 Hz, duty cycle to 50%;

[0062] 4) Set the power of the blue laser to 50W;

[0063] 5) The workpiece was subjected to jet polishing for 2 min, the electrolyte flow rate was 1 L / min, the liquid column diameter was 4 mm, the inter-electrode distance between the jet nozzle and the workpiece was h = 15 mm; the laser light outlet and the nozzle liquid outlet were kept coaxial and the relative distance between the two was 239 nm.

[0064] The surface roughness after polishing was tested and it was found that the surface roughness was reduced from 662nm to 206nm.

[0065] Tests show that the reflectivity of the polished material is significantly improved and the roughness is significantly reduced by 320%-390%.

[0066] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A laser-jet electrochemical hybrid polishing method, characterized in that: The method is: (1) Clean and air-dry the surface of the stainless steel to be treated; (2) The stainless steel pretreated in step (1) is clamped on a workbench as an anode, and the nozzle is used as a cathode. The nozzle is vertically aligned with the anode workpiece, the laser light outlet and the nozzle liquid outlet are kept coaxial and the relative distance between the two is adjusted to 234-254 mm, the water pump is started, and the electrolyte is sprayed toward the stainless steel workpiece through the nozzle. At the same time, the laser is turned on to irradiate the galvanic action area to perform laser-jet electrochemical hybrid polishing; The electrolyte composition of the polishing is: NaCl 58.44 g / L, the solvent is a mixed solvent of ethanol, ethylene glycol and glycerol in a volume ratio of 2:8:1; The electrical process parameters for polishing are: constant voltage mode, pulse power supply voltage is adjusted to 300-600V, pulse frequency is 50-600Hz, duty cycle is 20-60%; power supply is pulse power supply; The laser process parameters for polishing are: the laser power is adjusted to 50-80W; the light source is a blue light laser.

2. The laser-jet electrochemical hybrid polishing method according to claim 1, characterized in that: The processing time of laser-jet electrochemical hybrid polishing is 2-3 minutes.

3. The laser-jet electrochemical hybrid polishing method according to claim 1, characterized in that: The flow rate of the electrolyte fluid is 1-2 L / min, and the diameter of the liquid column is 4 mm.

4. The laser-jet electrochemical hybrid polishing method according to claim 1, characterized in that: The cathode stainless steel liquid flow nozzle is a through cylinder with an inner diameter of 4 mm and an outer diameter of 8 mm. The inter-electrode distance between the nozzle and the workpiece is h=8-30 mm.

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