A laser surface blackening method for high anti-metal

Abstract

The application relates to a laser surface blackening method for high anti-metal, characterized by comprising the following steps: cleaning; setting a laser blackening processing area and laser blackening process parameters; blowing an auxiliary gas to the processing area, wherein the auxiliary gas is industrial pure oxygen or a mixed gas with an oxygen content of greater than or equal to 35%; and starting a nanosecond pulse laser processing system to perform surface blackening treatment. The laser surface blackening method with the auxiliary gas is lower in cost and can significantly reduce reflectivity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of surface treatment, in particular to a laser surface blackening treatment method for high-reflectivity metal surfaces. BACKGROUND

[0002] Metal surface blackening refers to significantly reducing the optical reflectivity of a metal surface through surface treatment, which has wide application requirements in the fields of optical sensing and imaging, photovoltaics and thermal photovoltaic power generation, military stealth, and surface marking. Traditional metal surface blackening methods mainly use chemical treatment, which causes serious environmental pollution and makes it difficult to achieve local blackening of complex metal components.

[0003] Laser blackening treatment usually places the metal in an air environment and uses pulsed laser direct ablation to significantly improve the absorption of different waveband light by the metal surface by removing the microstructure and surface micro-nano scale deposits generated by ablation.

[0004] However, commonly used high-reflectivity metal materials such as copper, aluminum, and titanium have high reflectivity to laser. During the interaction between laser and materials, only a small amount of beam energy is absorbed by the materials. In conventional cases, it is difficult to significantly reduce the surface optical reflectivity and achieve surface blackening using nanosecond laser treatment. High-reflectivity metal surface blackening treatment usually requires picosecond / femtosecond ultrafast laser processing with extremely high single-pulse energy, which is costly and energy-intensive.

[0005] Therefore, there is a need for a high-reflectivity metal laser surface blackening method that is less costly and can significantly reduce reflectivity. SUMMARY

[0006] The present application solves the technical problem of providing a high-reflectivity metal laser surface blackening method that is less costly and can significantly reduce reflectivity.

[0007] The technical solution adopted by the present application to solve the above technical problems is:

[0008] The high-reflectivity metal laser surface blackening method comprises the following steps:

[0009] a. Clean the metal component to be blackened;

[0010] b. Place the metal component in the nanosecond pulsed laser processing system laser focal point position, set the laser blackening processing area and the laser blackening process parameters;

[0011] c. Blow auxiliary gas to the processing area, the auxiliary gas being industrial pure oxygen or a mixed gas with an oxygen content of 35% or more;

[0012] d, turn on the nanosecond pulse laser processing system, and perform surface blackening treatment.

[0013] The nanosecond pulse laser processing system of the present application can adopt a conventional nanosecond pulse laser processing system, and the auxiliary gas blowing can adopt a conventional gas blowing device.

[0014] Preferably, the metal member in step a is a high-reflective metal material such as aluminum, copper, titanium, etc.

[0015] Preferably, the cleaning in step a uses an organic solvent such as alcohol.

[0016] Preferably, the process parameters for laser blackening in step b are as follows: the average power of nanosecond laser is 20-1500 W; the laser pulse repetition frequency is 1-70 kHz; the laser pulse width is 1-500 ns; the spot diameter is 20-100 μm; the filling line spacing is 10-120 μm; the scanning speed is 10-2000 mm / s; and the scanning times are 6-80 times. The above parameters are used to process a micro-nano composite structure by reciprocating scanning of nanosecond laser on the high-reflective metal material, so as to realize surface blackening.

[0017] Further preferably, the process parameters for laser blackening in step b are as follows: the average power of nanosecond laser is 50-1000 W; the laser pulse repetition frequency is 10-70 kHz; the laser pulse width is 5-50 ns; the spot diameter is 25-60 μm; the filling line spacing is 20-80 μm; the scanning speed is 50-500 mm / s; and the scanning times are 10-40 times.

[0018] Further preferably, the process parameters for laser blackening in step b are as follows: the average power of nanosecond laser is 50-300 W; the laser pulse repetition frequency is 30-60 kHz; the laser pulse width is 10-30 ns; the spot diameter is 25-50 μm; the filling line spacing is 30-60 μm; the scanning speed is 100-300 mm / s; and the scanning times are 15-30 times.

[0019] The filling mode of laser can be a conventional filling mode such as grid filling, parallel line filling, cross filling, etc., and preferably, the filling mode is grid filling.

[0020] Preferably, the mixed gas in step c further comprises at least one gas selected from nitrogen, carbon dioxide, argon, etc. in addition to oxygen.

[0021] Preferably, the oxygen content of the mixed gas in step c is ≥55%, and further preferably, the oxygen content of the mixed gas is ≥60%. Further preferably, the oxygen content of the mixed gas is ≥75%.

[0022] Preferably, the flow rate of the auxiliary gas in step c is in the range of 2-50 L / min, ensuring that the processing zone can be fully purged with the auxiliary gas. Further preferably, the flow rate of the auxiliary gas in step c is in the range of 5-30 L / min.

[0023] Compared with the prior art, the present application has the advantages of:

[0024] 1. The present application uses nanosecond laser in combination with auxiliary gas. The nanosecond laser interacts with the material to remove the material, and the removal of the material produces a reticular microstructure. At the same time, due to the addition of the auxiliary gas, a large number of nanoscale oxides are generated on the surface of the microstructure. The micro-nano composite structure and oxides obtained on the laser processing surface synergistically act to significantly reduce the optical reflectivity.

[0025] 2. By the action of the auxiliary gas rich in oxygen, the laser blackening process simultaneously occurs with an oxidation reaction, which promotes the laser removal of the material and significantly improves the efficiency of nanosecond laser blackening processing.

[0026] 3. The present application uses nanosecond laser in combination with auxiliary gas to achieve high-reflectivity laser blackening. No expensive picosecond / femtosecond ultrafast laser processing equipment is needed, and only a simple modification of the existing nanosecond pulse laser processing system is required, i.e. the installation of a gas purging device, which greatly reduces the production cost. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Figure 1 is a surface micro-morphology diagram of the red copper after blackening treatment according to Example 1 of the present application;

[0028] Figure 2 Figure 2 is an energy spectrum diagram of the red copper after nanosecond laser blackening treatment according to Example 1 of the present application;

[0029] Figure 3 Figure 3 is a surface macro-morphology photograph of the red copper after nanosecond laser blackening treatment according to Example 1 of the present application;

[0030] Figure 4 Figure 4 is an optical reflectivity test diagram of the red copper after nanosecond laser blackening treatment according to Example 1 of the present application;

[0031] Figure 5 Figure 5 is a surface macro-morphology photograph of the red copper after nanosecond laser blackening treatment according to Comparative Example 1 of the present application;

[0032] Figure 6 Figure 6 is an optical reflectivity test diagram of the red copper after nanosecond laser blackening treatment according to Comparative Example 1 of the present application;

[0033] Figure 7 Figure 7 is a surface macro-morphology photograph of the 6061 aluminum alloy after nanosecond laser blackening treatment according to Example 2 of the present application;

[0034] Figure 8 Figure 2 is a test chart of optical reflectivity of the 6061 aluminum alloy after the nanosecond laser blackening treatment of Example 2 of the present application. DETAILED DESCRIPTION

[0035] The present application will be described in further detail below with reference to the accompanying drawings and examples. In the examples, the specific conditions not mentioned are carried out according to the conventional conditions or the conditions recommended by the manufacturers. The reagents or instruments used are not specified by the manufacturers, and are all conventional products that can be purchased on the market.

[0036] Example 1:

[0037] The laser surface blackening treatment method for high-reflective metals includes the following steps:

[0038] (1) Red copper is selected as the sample to be laser blackened, and alcohol is used to clean the surface contaminants such as oil stains before blackening treatment;

[0039] (2) The laser blackening area is set to a square area of 10 mm x 10 mm, an infrared nanosecond fiber laser processing system is selected, the surface of the copper to be blackened is placed near the focal point of the laser beam, the laser power is set to 70 W, the spot diameter is 30 μm, the pulse width is 24 ns, the repetition frequency is 55 kHz, the filling mode is grid filling, the filling line spacing is 20 μm, the scanning speed is 200 mm / s, and the scanning times are 20.

[0040] (3) Turn on the oxygen auxiliary gas, and blow the industrial pure oxygen to the processing area at a flow rate of 15 L / min.

[0041] (4) Turn on the nanosecond processing system and directly perform surface blackening treatment under the assistance of oxygen.

[0042] (5) Combined with the surface macro / micro and energy spectrum analysis results of the laser blackening processing, Figures 1-3 after 20 times of scanning under the assistance of oxygen, the processing area is black, and the micro / nano composite structure is generated on the processing surface due to material removal and deposition of copper oxide particles. As shown in Figure 4 , the reflectivity of the material to light in the wavelength range of 200-1400 nm is less than 30%, and the blackening effect of the processing area is significant. Through the auxiliary effect of oxygen, the nanosecond laser blackening of high-reflective copper is realized.

[0043] Comparative Example 1:

[0044] The laser surface blackening treatment method for high-reflective metals includes the following steps:

[0045] (1) Red copper is selected as the sample to be laser blackened, and alcohol is used to clean the surface contaminants such as oil stains before blackening treatment;

[0046] (2) Set the laser blackening area to a square area of 10 mm x 10 mm, select an infrared nanosecond fiber laser processing system, place the surface to be blackened of red copper near the focal point of the laser beam, set the laser power to 70 W, the spot diameter to 30 μm, the pulse width to 24 ns, the repetition frequency to 55 kHz, the filling mode to grid filling, the filling line spacing to 20 μm, the scanning rate to 200 mm / s, and the scanning number to 20 times.

[0047] (3) Turn on the nanosecond processing system and directly perform surface blackening treatment in an air environment.

[0048] (4) In combination with the test results of the macroscopic morphology of the laser blackened surface and the reflectivity of the blackened surface in Figure 5 and Figure 6 , after scanning 20 times in an air environment, only a small amount of black color is generated at the edge of the processing area, the material reflectivity is not significantly reduced, and the laser blackening effect is not achieved.

[0049] Example 2:

[0050] The laser surface blackening treatment method for high-reflective metals comprises the following steps:

[0051] (1) Select 6061 aluminum alloy as the sample to be laser blackened, and clean the surface of contaminants such as oil stains with alcohol before blackening treatment;

[0052] (2) Set the laser blackening area to a square area of 10 mm x 10 mm, select an infrared nanosecond fiber laser processing system, place the surface to be blackened of aluminum alloy near the focal point of the laser beam, set the laser power to 56 W, the spot diameter to 30 μm, the pulse width to 24 ns, the repetition frequency to 55 kHz, the filling mode to grid filling, the filling line spacing to 30 μm, the scanning rate to 300 mm / s, and the scanning number to 15 times.

[0053] (3) Turn on the auxiliary gas, which is industrial pure oxygen in this embodiment, and blow the auxiliary gas to the processing area at a flow rate of 15 L / min.

[0054] (4) Turn on the nanosecond processing system and directly perform surface blackening treatment in the auxiliary gas.

[0055] (5) In combination with the test results of the macroscopic morphology of the laser blackened surface and the reflectivity of the blackened surface in Figure 7 and Figure 8 , after the above blackening treatment, the processing area of the aluminum plate in this embodiment is black, the material reflectivity to light in the wavelength range of 200-1400 nm is less than 30%, and excellent blackening effect is achieved.

[0056] Example 3

[0057] The laser surface blackening treatment method for high anti-metal, comprising the following steps:

[0058] (1) Select titanium plate as the laser blackening sample, and clean the surface oil stains and other pollutants with alcohol before blackening treatment;

[0059] (2) Set the laser blackening area as a square area of 10mm*10mm, select an infrared nanosecond fiber laser processing system, place the surface of the titanium plate to be blackened near the laser beam focus point, set the laser power to 65W, the spot diameter to 40μm, the pulse width to 40ns, the repetition frequency to 30kHz, the filling mode to grid filling, the filling line spacing to 50μm, the scanning rate to 300mm / s, and the scanning times to 25.

[0060] (3) Turn on the auxiliary gas, and the auxiliary gas composition of the embodiment is: oxygen content 65%, and the rest is nitrogen, blow the auxiliary gas to the processing area, and the gas flow is 15L / min.

[0061] (4) Turn on the nanosecond processing system, and directly perform surface blackening treatment under the auxiliary gas.

[0062] (5) After the above blackening treatment, the processing area of the titanium plate of the embodiment is black, the material has a reflectivity of less than 20% to light in the wavelength range of 200-1400nm, and the blackening effect of the processing area is remarkable.

[0063] The technical means disclosed in the present application is not limited to the technical means disclosed in the above embodiment, but also includes the technical solutions composed of any combination of the above technical features. It should be noted that for ordinary skilled persons in the art, without departing from the principles of the present application, some improvements and refinements can be made, and these improvements and refinements are also considered within the protection scope of the present application.

Claims

1. A laser surface blackening method for high anti-metallic, characterized by The method comprises the following steps: a. cleaning the metal component to be blackened, the metal component being any one of aluminum, copper, titanium, and other high-reflectivity metal materials; b. placing the metal component in the focal point position of an infrared nanosecond pulse laser processing system, setting the laser blackening processing area, and setting the laser blackening process parameters; The laser blackening process parameters are: the average power of the nanosecond laser is greater than 50 and less than or equal to 1500 W; the laser pulse repetition frequency is 1-70 kHz; the laser pulse width is greater than or equal to 1 and less than 30 ns; the spot diameter is 20-100 microns; the fill line spacing is 10-120 microns; the scanning speed is 10-2000 mm / s; and the scanning times are 6-80 times; c. blowing auxiliary gas to the processing area, the auxiliary gas being industrial pure oxygen or a mixed gas containing oxygen in an amount of ≥35%; The flow rate of the auxiliary gas is 2-50 L / min; d. turning on the nanosecond pulse laser processing system to perform surface blackening treatment.

2. The laser surface blackening method for high-reflective metal facing according to claim 1, characterized in that: The metal component in step a is titanium.

3. The laser surface blackening method for high-reflective metal facing according to claim 1, characterized in that: The laser blackening process parameters in step b are: the average power of the nanosecond laser is greater than 50 and less than or equal to 1000 W; the laser pulse repetition frequency is 10-70 kHz; the laser pulse width is greater than or equal to 5 and less than 30 ns; the spot diameter is 25-60 microns; the fill line spacing is 20-80 microns; the scanning speed is 50-500 mm / s; and the scanning times are 10-40 times.

4. The laser surface blackening method for high-reflective metal facing according to claim 1, characterized in that: The laser blackening process parameters in step b are: the average power of the nanosecond laser is greater than 50 and less than or equal to 300 W; the laser pulse repetition frequency is 30-60 kHz; the laser pulse width is greater than or equal to 10 and less than 30 ns; the spot diameter is 25-50 microns; the fill line spacing is 30-60 microns; the scanning speed is 100-300 mm / s; and the scanning times are 15-30 times.

5. The laser surface blackening method for high-reflective metal facing according to any one of claims 3-4, characterized in that: The filling mode of the laser in step b is selected from any one of grid filling, parallel line filling, and cross filling.

6. The laser surface blackening method for high-reflective metal facing according to claim 1, wherein: The mixed gas in step c further comprises at least one of nitrogen, carbon dioxide, and argon in addition to oxygen.

7. The laser surface blackening method for high-reflective metal facing according to claim 6, characterized in that: The oxygen content of the mixed gas in step c is ≥55%.

8. The laser surface blackening method for high-reflective metal facing according to claim 7, characterized in that: The oxygen content of the mixed gas in step c is ≥60%.

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