Gas explosion film stripping method for PVD film on metal surface

Abstract

The application provides a gas explosion film stripping method suitable for PVD film layers on metal surfaces, which is characterized by the following steps: in the first stage of film stripping, defects such as break points and micro cracks are triggered at the weak interface between the film and the substrate by using the physical property difference between the film and the substrate, even local cracks are formed through the weak part of some film layers, the electrolysis process is started, the film layer becomes a loose and soft "bread" with many defects, and the core of the second stage of gas explosion is provided; in the second stage, the ionized bubbles of the workpiece surface are ionized by using the high-energy impact of high-voltage and high-current transient, the gas explosion is formed, and the film layer with loose defects is quickly stripped by the inside-outside clamping and inside-outside cooperation; in the third stage, the surface of the substrate is cleaned and shaped by the continuous and stable medium-pressure gas explosion, the film stripping is ensured to be complete, and the quality of the workpiece surface after film stripping is guaranteed. The gas explosion film stripping method is simple, efficient, green and environment-friendly, and the quality of the film-stripped workpiece is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of surface treatment, in particular to a gas explosion film stripping method suitable for PVD film layer on metal surface. BACKGROUND

[0002] PVD is a common vacuum vapor deposition technology, which has the advantages of high density, strong film-substrate adhesion, good uniformity, large film forming area, etc. It is an effective means for preparing high-performance thin films on metal surfaces, which can significantly improve the visual appearance and performance of metal products, and even obtain certain new functions that the base metal does not have. It is of great significance to improve the service life, reliability and expand the application field of metal products. Therefore, metal PVD is widely used.

[0003] However, the normal yield of mature PVD production line is about 95% to 99%, and PVD film defects are difficult to avoid. Replating after stripping of defective products is the main method to avoid scrapping of PVD products. Stripping not only requires complete removal of PVD old film, but also requires the substrate surface to be intact, without deformation and corrosion, which is technically difficult. Manual grinding and polishing is the most primitive stripping method, and the stripping effect is completely controlled by the skill level of workers. It requires high labor skills, and the film layer is not completely removed and the substrate is over-polished, which often occurs. It also has problems such as low efficiency, high cost and dust pollution, so it has been less used.

[0004] Chemical stripping and electrolytic stripping are the most popular stripping methods in the industry. Both methods require the workpiece to be immersed in stripping solution, relying on the chemical corrosion or electrolysis of the stripping solution to dissolve and strip the film layer. Both methods use chemical force as the main energy for stripping. The stripping solution often contains strong acid, strong base and volatile toxic substances (nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, chromic acid, potassium permanganate, hydrogen peroxide, sodium hydroxide, alcohol, etc.), which are harmful to human safety and environmental safety. At the same time, chemical force has strong specificity, and stripping solution is only effective for specific materials. Therefore, once the composition of the substrate or the film layer changes, the formula of the stripping solution also needs to be adjusted, so its scope of application is also very limited.

[0005] In addition, the thickness, wear resistance and corrosion resistance of the film layer also affect the stripping efficiency. Carbides, nitrides and oxides with good wear resistance and corrosion resistance, as well as their multi-layer composite films, may need 10 to 20 hours to effectively strip the film layer. The specific stripping time needs to be controlled artificially according to the state of the film layer and the stripping solution, and it is often difficult to balance the completeness of stripping and the integrity of the substrate. After chemical stripping, many products, especially polished PVD products, generally need to be polished and shaped again, and then go through a complete set of pre-plating cleaning (alkali washing and acid washing) before they can be plated again. Not only is the process complex, but it also affects the precision of the product. SUMMARY

[0006] The present application aims at the deficiencies of the prior art, and provides a gas explosion film stripping method suitable for PVD film layers on metal surfaces.

[0007] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0008] A gas explosion film stripping method suitable for PVD film layers on metal surfaces, comprising the following steps:

[0009] S1, preparing a stripping solution, adding the prepared stripping solution into a processing tank of a stripping system, and preheating; wherein the stripping solution is an aqueous solution of water-soluble active metal oxygen-containing acid salt;

[0010] S2, stably hanging the workpiece to be stripped in a clamp, loading the clamp into a processing position of the processing tank of the stripping system, stably connecting the clamp to the positive pole of a power supply, and completely immersing the workpiece in the stripping solution;

[0011] S3, stripping according to the set stripping process parameters; wherein the stripping process comprises the following three stages:

[0012] The first stage is to set the voltage and current, so that the heat generated acts on the PVD film layer on the workpiece, loosens the inside of the PVD film layer, and makes the PVD film layer have break points and crack defects;

[0013] The second stage is to adjust the voltage and current, so that the energy generated promotes the break points and crack defects generated in the first stage to develop rapidly, and the energy breaks through the gas electrolyzed on the surface of the workpiece, so that the gas ionization explosion forms a gas explosion, thereby stripping the PVD film layer;

[0014] The third stage is to adjust the voltage and current, so that a continuous and stable gas explosion is formed on the surface of the workpiece, stubborn attachments are removed, the PVD film layer is completely removed, and the workpiece is cleaned and shaped;

[0015] S4, after the stripping is completed, the workpiece after stripping is cleaned and dried, and PVD film plating is performed again.

[0016] In an optional embodiment, the concentration of the water-soluble active metal oxygen-containing acid salt in the stripping solution is 1-2 wt.%.

[0017] In an optional embodiment, the water-soluble active metal oxygen-containing acid salt is one or more of sodium sulfate, magnesium sulfate and potassium sulfate.

[0018] In an optional embodiment, the stripping solution also contains a surfactant with a concentration of 0.1-1 wt.%.

[0019] In an optional embodiment, the surfactant is an anionic surfactant, or a mixture of an anionic surfactant and a non-ionic surfactant.

[0020] In an optional embodiment, the anionic surfactant is one or more of sodium stearate, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium fatty alcohol polyoxyethylene ether sulfate, etc., and the non-ionic surfactant is a fatty alcohol polyoxyethylene ether.

[0021] In an optional embodiment, in the step S1, the preheating temperature of the stripping solution is 50-70°C.

[0022] In an optional embodiment, in the step S3, the first stage uses short-time low-voltage medium current, with a voltage setting of 5-30V, a current setting of 10-100A, and a working time of 3-20s. The film base physical property difference triggers defects such as break points and micro-cracks at the weak interface of the film base, and even forms local cracks through some weak places of the film layer, starts the electrolysis process, and makes the film layer become a loose "bread" with many defects inside, i.e. a "core" for gas explosion, and prepares for the second stage of gas explosion.

[0023] In an optional embodiment, in the step S3, the second stage uses short-time high-voltage high-current, with a voltage setting of 350-500V, a current setting of 30-300A, and a working time of 3-20s. The high energy generated by the high voltage and high current at the moment breaks through the gas to realize ionization explosion and form a gas explosion, and the film layer is quickly stripped through the inside-outside clamping and inside-outside cooperation.

[0024] In an optional embodiment, in the step S3, the third stage uses timely medium-voltage medium-current, with a voltage setting of 250-320V, a current setting of 3-100A, and a working time of 10-150s. The purpose is to realize stable stripping of the PVD film layer and cleaning and flattening of the metal surface.

[0025] Compared with the prior art, the present application has the following remarkable advantages:

[0026] The gas explosion film stripping method suitable for the PVD film layer on the metal surface of the present application has the following three stages: in the first stage, defects such as break points and micro cracks are triggered at the weak interface between the film and the substrate by using the physical property difference between the film and the substrate, and even local cracks are formed through some weak parts of the film, so that the electrolysis process is started and the film layer becomes a loose "bread" with many defects, which provides the core for the second stage; in the second stage, the ionized bubbles on the surface of the workpiece are ionized by using the high-energy impact of high voltage and high current, so that the gas explosion is formed, and the film layer with loose defects is quickly stripped by the inside-out and outside-in attack; in the third stage, the surface of the substrate is cleaned and shaped by the continuous and stable medium-pressure gas explosion, so that the stripping is completely ensured, and the surface quality of the workpiece after stripping is guaranteed. Meanwhile, the presence of the surfactant in the stripping solution greatly reduces the surface tension of the stripping solution on the product, and improves the wetting ability of the stripping solution on the defect points, so that the uniform stripping of the film layer is achieved.

[0027] The gas explosion film stripping method of the present application has the characteristics of simple operation, short process and high efficiency. The product does not need complex pretreatment before processing, and although the processing is carried out in stages, all the processing parameters can be set through the control system, so the operation is simple, the whole processing process only takes tens of seconds to a few minutes, and manual intervention is not needed, so the processing efficiency is high. At the same time, the gas explosion can also effectively remove the product surface attachments, so that the surface cleanliness of the obtained product is high, the pressure of the subsequent PVD pre-cleaning is greatly reduced, and the PVD pre-acid washing and alkali washing process is obviously shortened.

[0028] The gas explosion film stripping method of the present application uses stripping solution raw materials with low cost, which can be recycled, has a long service life, and has low comprehensive use cost. Moreover, the solute of the stripping solution itself is non-toxic and harmless, the surfactant is added in a small amount and meets the national emission standards, the old liquid can be recycled or directly discharged after treatment such as precipitation, filtration and impurity removal, the processing process is harmless to the human body and environment, and there is no difficulty in post-processing of waste liquid after processing, so the environmental protection performance is high.

[0029] The gas explosion film stripping method of the present application belongs to the surrounding processing mode, so it can also effectively strip the internal film layer of the product, can realize the integrated stripping of the PVD workpiece with complex structures such as grids and holes, and has a wide range of application structures. At the same time, the main stripping force of the present application is physical type, so the stripping of various film layers on the surface of the substrate can be realized by selecting a suitable stripping solution system according to the substrate material, without the need to adjust the stripping solution system according to the composition change of the film layer. That is, the present application is not only suitable for various metal substrates such as stainless steel, titanium alloy and high-temperature alloy, but also can realize the effective stripping of various film layers on the same substrate by using one stripping solution, so it has a wide range of use and has a broad industrial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is the process flow chart of the gas explosion film stripping method suitable for the PVD film layer on the metal surface of the present application.

[0031] Figure 2 Figure 1 is a schematic diagram of a film stripping device for the gas explosion film stripping method for PVD film layers on metal surfaces according to the present application.

[0032] Figure 3 Figure 2 is a schematic diagram of the film stripping process for the gas explosion film stripping method for PVD film layers on metal surfaces according to the present application.

[0033] Figure 4 Figure 3 is a picture of a metal surface before film stripping (a) and after film stripping (b) in Example 1 of the present application. Figure 4 Figure 4 is a picture of a metal surface before film stripping (a) and after film stripping (b) in Example 2 of the present application. Figure 4 Figure 5 is a picture of a metal surface before film stripping (a) and after film stripping (b) in Example 3 of the present application.

[0034] Figure 5 Figure 6 is a picture of a metal surface before film stripping (a) and after film stripping (b) in Example 4 of the present application. Figure 5 Figure 5

[0035] Figure 6 Figure 6 Figure 6

[0036] Figure 7 Figure 7 Figure 7 DETAILED DESCRIPTION

[0037] In order to better understand the technical content of the present application, specific embodiments are described below with reference to the accompanying drawings.

[0038] Aspects of the present application are described in the following detailed description and in reference to the drawings, in which numerous specific embodiments are shown. The embodiments of this disclosure need not necessarily include all aspects of the present application. It should be understood that various concepts and embodiments introduced above and described in more detail below can be implemented in any of numerous ways, as will be apparent to one of skill in the art.

[0039] The present application provides a simple, efficient, high-quality, environmentally friendly film stripping method for PVD film layers on various metal surfaces, to solve the problems of existing film stripping technologies, such as too much manual intervention, low efficiency, unsatisfactory results, limited application range, and poor environmental protection, and to achieve efficient, high-quality, low-cost, and environmentally friendly film stripping of PVD film layers on various metal surfaces.

[0040] In combination with Figures 1-3 Figure 1, in an exemplary embodiment of the present application, a gas explosion film stripping method for PVD film layers on metal surfaces is provided, comprising the following steps:

[0041] ​​​​​​​​S1, prepare the stripping solution 1, and add the prepared stripping solution into the processing tank 2 of the stripping system and preheat; wherein the stripping solution is an aqueous solution of water-soluble active metal oxygen-containing acid salt;

[0042] S2, stably hang the workpiece 3 to be stripped in the clamp 4, and load the clamp into the processing position of the processing tank of the stripping system, stably connect the positive electrode of the power supply 5, and make the workpiece completely immersed in the stripping solution, and connect the negative electrode of the power supply 5 with the cathode conductor 6;

[0043] S3, set the processing process parameters through the control system 7, start the system, and start stripping according to the set stripping process parameters; wherein the stripping process includes the following three stages:

[0044] The first stage is to set the voltage and current, and through the generated heat, the internal of the PVD film layer 8 on the workpiece is loosened, and the PVD film layer has break points and crack defects;

[0045] The second stage is to adjust the voltage and current, so that the energy generated promotes the break points and crack defects generated in the first stage to develop rapidly, and the energy breaks through the gas electrolytically resolved from the surface of the workpiece, so that the gas ionization explosion forms a gas explosion, thereby stripping the PVD film layer;

[0046] The third stage is to adjust the voltage and current, so that a continuous and stable gas explosion is formed on the surface of the workpiece, the stubborn attachments are removed, the PVD film layer is completely removed, and the workpiece is cleaned and shaped;

[0047] S4, after the stripping is completed, the workpiece after stripping is cleaned and dried, and PVD film coating is performed again.

[0048] In the optional embodiment, in the stripping solution, the stripping solution solvent is tap water, and the solute is mainly cheap and easily available water-soluble active metal oxygen-containing acid salt, for example, one or more of sodium sulfate, magnesium sulfate and potassium sulfate, etc., and the concentration is 1-2 wt.%. The stripping solution itself is non-toxic and harmless, and the whole is neutral.

[0049] It should be understood that the water-soluble active metal oxygen-containing acid salt is used as a conductive medium, including but not limited to one or more of sodium sulfate, magnesium sulfate and potassium sulfate, and can also be other water-soluble active metal oxygen-containing acid salts, and when mixed with multiple substances, the ratio between the substances is arbitrary, as long as the total concentration of the solute in the stripping solution is 1-2 wt.%.

[0050] The main anion discharge sequence in the stripping solution is OH - After that, the cation discharge sequence is H +Previously, during the stripping process, the ionized component was mainly water, and the electrolyte primarily served a conductive function rather than participating in the reaction and being consumed. Therefore, the solute concentration only needed to be maintained within a reasonable range to sustain conductivity, without requiring an excessively high concentration. Furthermore, small amounts of residual impurities in tap water would not significantly affect the stripping effect, allowing for the direct preparation of the stripping solution with tap water, thus resulting in lower raw material costs.

[0051] In an optional embodiment, the stripping solution also contains a surfactant at a concentration of 0.1 to 1 wt.%.

[0052] In an optional embodiment, the surfactant is an anionic surfactant, or a mixture of anionic and nonionic surfactants.

[0053] In optional embodiments, the anionic surfactant is selected from sodium stearate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium fatty alcohol polyoxyethylene ether sulfate, etc., and the nonionic surfactant is fatty alcohol polyoxyethylene ether.

[0054] It should be understood that when multiple surfactants are added, the proportions between the substances can be arbitrary, as long as the total concentration of surfactant in the stripping solution is 0.1 to 1 wt.%.

[0055] The surfactants described above are non-toxic and non-irritating, with good biodegradability and hard water resistance, allowing for direct discharge. Even at low concentrations, they significantly reduce the surface tension of the solution, improving the wetting ability of the stripping solution on defect points, thus facilitating uniform film peeling and preventing damage to localized substrates. Simultaneously, surfactants effectively promote dirt dispersion, preventing the detached film from adhering to the product surface and affecting the stripping effect.

[0056] In an optional embodiment, in step S1, the preheating temperature of the stripping solution is 50-70°C to provide a heat accumulation base point for the first stage of processing and shorten the heat-induced deformation time.

[0057] In an optional implementation, in step S3, the voltage of the first stage is set to 5-30V, the current is set to 10-100A, and the working time is 5-30s.

[0058] like Figure 3 As shown, after the processing starts, under the action of the electric field, a current channel is formed between the workpiece to be stripped and the cathode conductor through the stripping solution. According to Joule-Lenz law (Formula (1))

[0059] Q = I 2 Rt (1)

[0060] Wherein, Q: heat generated by current through the conductor, unit: Joule (J); I: current through the conductor, unit: ampere (A); R: resistance of the conductor, unit: ohm (Ω); t: on-time, unit: second (s).

[0061] The current and time through the substrate and the film layer during processing are the same, but the resistance of the two is obviously different, so the heat generated by the two during operation is obviously different, and the film layer has a large resistance value and generates more heat.

[0062] At the same time, considering the influence of volume and thermal conductivity, the metal substrate has a large volume and good thermal conductivity, and generally does not deform obviously, while the PVD film layer is not only thin and small in volume, but also poor in thermal conductivity, so it will deform obviously under the action of heat.

[0063] The deformation difference between the metal substrate and the film layer will inevitably form a series of defects such as breakpoints and micro-cracks at the bonding interface between the metal substrate and the PVD film layer, and the defects already existing at the bonding interface will rapidly develop under the action of heat, and even form local cracks / gaps that penetrate some weak places of the film layer, forming a contact channel between the metal and the stripping solution. After the channel is formed, the electrolytic gas is started to be precipitated, and the gas further drives the stripping solution to be disturbed and the defect points to be deformed, further promoting the development of the defect points.

[0064] The goal of this stage is to make the dense PVD film layer into a soft "bread" shape with loose internal defects, i.e. to cultivate the "core" of the gas explosion in the next stage, and to prepare for the second stage of gas explosion.

[0065] In an optional embodiment, in the step S3, the voltage of the second stage is set to 350-500V, the current is set to 30-300A, and the working time is 3-15s.

[0066] As shown in Figure 3 The second stage of high voltage and high current produces a sharp high energy, which not only promotes the rapid development of the existing defects such as breakpoints and cracks in the first stage, but also breaks through the gas electrolytic precipitated on the surface of the workpiece, making the gas ionization explode and forming a rapid gas explosion to rapidly strip the film layer. At the same time, the violent energy fluctuation caused by the gas explosion not only greatly accelerates the movement of the stripping solution and promotes the development of the surrounding original defect points, but also derives new defect points and new gas explosion "cores", realizes the synchronous stripping and chain stripping of the film layers at different positions, and thus realizes the rapid and uniform stripping of the PVD film layer.

[0067] In an optional embodiment, in the step S3, the voltage of the third stage is set to 250-320V, the current is set to 3-100A, and the working time is 10-150s.

[0068] As shown in Figure 3As shown, the third stage is intended to form a continuous stable medium-pressure gas explosion on the surface of the workpiece to achieve complete removal of stubborn adhesion, ensure complete removal of the PVD film layer, and clean the surface of the workpiece, so that the metal substrate surface can be shaped by gas explosion, and the surface quality is further improved.

[0069] For better understanding, the application will be further described below in conjunction with specific examples, but the materials and processing technology are not limited thereto, and the content of the application is not limited thereto.

[0070] Example 1

[0071] The product to be stripped is a polished stainless steel round bright piece with a diameter of 40 mm and a thickness of 2 mm, and the surface is covered with a silver-gray chromium nitride PVD film layer with a thickness of 1.2 microns.

[0072] Step 1: Configure the stripping solution, including: configuring a stripping solution composed of tap water, 1.4% by mass fraction of sodium sulfate and 0.6% by mass fraction of linear dodecyl benzene sulfonic acid sodium in the working tank, mixing uniformly and heating to 50℃;

[0073] Step 2: Put in the workpiece, including: stably loading the PVD workpiece to be stripped into the clamp, loading the clamp into the processing slot of the stripping system processing slot, ensuring stable connection with the positive electrode of the power supply, and ensuring that the stripping solution can completely cover the workpiece;

[0074] Step 3: Set the processing parameters through the control system, the first stage: voltage 25V, current 60A, working time 15s; the second stage: voltage 360V, current 80A, working time 5s; the third stage: voltage 270V, current 60A, working time 30s; start the system and begin stripping;

[0075] Step 4: After stripping is completed, clean and dry the workpiece.

[0076] As Figure 4 shown, the surface state of the workpiece before stripping Figure 4 (a) and after stripping Figure 4 (b) can be observed, and it is found that the silver-gray chromium nitride film layer on the surface of the workpiece has been completely removed without residue, the surface of the workpiece is smooth and bright, there are no corrosion pits, and the mirror effect is good; and the size is measured by a vernier caliper, and the results are shown in Table 1, which shows that stripping does not significantly affect the size of the workpiece.

[0077] Table 1

[0078]

[0079] Example 2

[0080] The product to be stripped is a high-temperature alloy cylinder with a height of 20.06 mm, a large diameter of 29.99 mm, and a small diameter of 34.98 mm. The surface is covered with a black chromium carbide PVD film with a thickness of 0.9 micrometers.

[0081] Step 1: Prepare the stripping solution, including: prepare a stripping solution in the working tank consisting of tap water, 2% magnesium sulfate, 0.2% sodium stearate, 0.3% sodium dodecylbenzene sulfonate, and 0.1% sodium fatty alcohol polyoxyethylene ether sulfate, mix them evenly and heat to 70°C.

[0082] Step 2: Place the workpiece, including: stably loading the PVD stripping workpiece into the fixture, loading the fixture into the processing position of the stripping system processing tank, ensuring a stable connection with the positive power supply, and ensuring that the stripping solution can completely submerge the workpiece.

[0083] Step 3: Set the processing parameters through the control system. First stage: voltage 30V, current 80A, working time 7s; Second stage: voltage 400V, current 150A, working time 5s; Third stage: voltage 260V, current 80A, working time 40s; Start the system and begin stripping.

[0084] Step 4: After the plating is removed, clean and dry the workpiece.

[0085] like Figure 5 As shown, the workpiece before deplating ( Figure 5 a) and after plating removal ( Figure 5 b) Surface condition comparison: The surface condition of the workpiece can be observed. It can be found that the film layer on the workpiece surface has been completely removed, the workpiece surface is flat and bright, and there are no corrosion pits.

[0086] The dimensions of the workpiece were measured using vernier calipers, and the results are shown in Table 2. It can be seen that the stripping process did not significantly affect the dimensional accuracy of the workpiece.

[0087] Table 2

[0088]

[0089] Example 3

[0090] The product to be deplated is a stainless steel dragon-shaped craft with a length of 150mm and a height of 28mm. The surface is covered with a TiCN golden yellow PVD film with a thickness of 1.8 micrometers.

[0091] Step 1: Prepare the stripping solution, including: prepare a stripping solution in the working tank consisting of tap water, 1.6% sodium sulfate, 0.2% sodium stearate, and 0.1% sodium dodecylbenzene sulfonate, mix them evenly and heat to 70°C;

[0092] Step 2: Place the workpiece, including: stably loading the PVD stripping workpiece into the fixture, loading the fixture into the processing position of the stripping system processing tank, ensuring a stable connection with the positive power supply, and ensuring that the stripping solution can completely submerge the workpiece.

[0093] Step 3: Set the processing parameters through the control system. First stage: voltage 15V, current 80A, working time 15s; Second stage: voltage 360V, current 240A, working time 5s; Third stage: voltage 270V, current 100A, working time 80s; Start the system and begin stripping.

[0094] Step 4: After the plating is removed, clean and dry the workpiece.

[0095] like Figure 6 As shown, the workpiece before deplating ( Figure 6 a) and after plating removal ( Figure 6 b) Surface condition comparison: The surface condition of the product can be observed. It is found that the film layer on the surface of the workpiece has been completely removed, and the film layer in the crevices has also been cleaned. The surface of the workpiece is flat and bright, with no obvious corrosion pits.

[0096] Example 4

[0097] The product being stripped of plating is an irregularly shaped titanium alloy craft with a length of 250mm and a height of 18mm. The surface is covered with a hard WCrC black PVD film with a thickness of 3.4 micrometers.

[0098] Step 1: Prepare the stripping solution, including: prepare the stripping solution in the working tank, which consists of local water, 1.7% sodium sulfate, 0.1% sodium dodecyl sulfate, 0.2% sodium linear dodecylbenzene sulfonate and 0.1% fatty alcohol polyoxyethylene ether, mix them evenly and heat to 70°C.

[0099] Step 2: Place the workpiece, including: stably loading the PVD stripping workpiece into the fixture, loading the fixture into the processing position of the stripping system processing tank, ensuring a stable connection with the positive power supply, and ensuring that the stripping solution can completely submerge the workpiece.

[0100] Step 3: Set the processing parameters through the control system. First stage: voltage 25V, current 60A, working time 10s; Second stage: voltage 420V, current 160A, working time 12s; Third stage: voltage 270V, current 60A, working time 100s; Start the system and begin stripping.

[0101] Step 4: After the plating is removed, clean and dry the workpiece.

[0102] like Figure 7 As shown, the workpiece before deplating ( Figure 7a) and after dealloying Figure 7 b) surface state contrast, the surface state of the workpiece can be observed, it is found that the surface film layer of the workpiece is completely removed, the surface film layer of the inner layer grid is also completely removed, and the overall surface of the workpiece is smooth and bright, without obvious corrosion pits.

[0103] As can be seen from the above, the gas explosion film removal method suitable for the PVD film layer of the metal surface can realize efficient and high-quality uniform removal of various PVD film layers on different metal surfaces, and can also realize synchronous adjustment of the surface state of the metal base material, the application range of the present application is wide, the operation is simple, the problem of PVD bad product dealloying can be effectively solved, PVD product scrapping is avoided, and the practical value is high.

[0104] Although the present application has been disclosed with the above preferred embodiments, it is not intended to limit the present application. Those skilled in the art can make various modifications and improvements without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application shall be subject to the definition of the claims.

Claims

1. A gas explosion decoction method for PVD films on metal surfaces, characterized in that, Includes the following steps: S1. Prepare the stripping solution, add the prepared stripping solution to the processing tank, and preheat it; wherein, the stripping solution is an aqueous solution containing a water-soluble active metal oxyacid salt, and the water-soluble active metal oxyacid salt is one or more of sodium sulfate, magnesium sulfate and potassium sulfate. S2. Hold the workpiece to be stripped stably in the fixture, install the fixture into the processing position of the processing tank, connect it stably to the positive terminal of the power supply, and make the workpiece completely immersed in the stripping solution. S3. Perform the stripping process according to the set stripping parameters; the stripping process includes the following three stages: In the first stage, the voltage and current are set, and the heat generated makes the interior of the PVD film on the workpiece loose and gives the PVD film defects such as breaks and cracks. The voltage in the first stage is set to 5~30V, the current is set to 10~100A, and the working time is 5~30s. In the second stage, the voltage and current are adjusted so that the generated energy promotes the rapid development of the breakpoints and cracks generated in the first stage. At the same time, the energy breaks down the gas electrolytically released from the workpiece surface, causing the gas to ionize and explode, thus forming a gas explosion and peeling off the PVD film layer. The voltage in the second stage is set to 350~500V, the current is set to 30~300A, and the working time is 3~15s. In the third stage, the voltage and current are adjusted to create a continuous and stable gas explosion on the workpiece surface, removing stubborn deposits, ensuring complete removal of the PVD film, and cleaning and shaping the workpiece. The voltage in the third stage is set to 250~320V, the current is set to 3~100A, and the working time is 10~150s. S4. After the plating is removed, clean and dry the workpiece, and then re-coat with PVD.

2. The gas explosion decoction method for PVD films on metal surfaces according to claim 1, characterized in that, The concentration of water-soluble active metal oxyacid salts in the stripping solution is 1~2 wt.%.

3. The gas explosion decoction method for PVD films on metal surfaces according to claim 1, characterized in that, The stripping solution also contains surfactants at a concentration of 0.1 to 1 wt.%.

4. The gas explosion decoction method for PVD films on metal surfaces according to claim 3, characterized in that, The surfactant is an anionic surfactant, or a mixture of anionic and nonionic surfactants.

5. The gas explosion decoction method for PVD films on metal surfaces according to claim 4, characterized in that, The anionic surfactant is one or more of sodium stearate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, and sodium fatty alcohol polyoxyethylene ether sulfate, and the nonionic surfactant is fatty alcohol polyoxyethylene ether.

6. The gas explosion decoction method for PVD films on metal surfaces according to claim 1, characterized in that, In step S1, the preheating temperature of the stripping solution is 50~70℃.

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