A method for laser-induced color texture pattern on titanium surface

Abstract

The invention discloses a method for laser-induced color texture pattern on titanium surface, comprising: step 1: grinding, polishing and cleaning the titanium alloy surface, drawing a pattern on the titanium alloy surface by using a laser, and continuously adjusting the parameters of the laser until a processing database in which the parameters of the laser and the color of the titanium alloy surface pattern are mutually correlated is obtained; step 2: using a colorimeter to measure and calibrate the color of the pre-drawn pattern with Lab values, calculating the color difference between the color of the pre-drawn pattern and each color in the processing database, and when the color difference is less than or equal to a predetermined value, selecting the parameters of the laser corresponding to the corresponding color for processing; the invention induces the generation of oxide film layers of different thicknesses and types on the titanium surface by a laser heat source with adjustable pulse width, makes the film layer present different colors through the interference, reflection and absorption of light, adjusts the spot size, controls the scanning speed, and is equipped with a high-speed galvanometer scanning system to realize the preparation of various fine patterns.

Description

Technical Field

[0001] The invention belongs to the technical field of laser processing, and in particular relates to a method for generating a color texture pattern on a titanium surface by laser induction. Background Art

[0002] In recent years, titanium and titanium alloy materials have been rapidly increasing in the civilian market due to their light weight, high strength, acid and alkali corrosion resistance, good biophilicity and natural antibacterial properties, and the demand for surface coloring is also increasing. At present, the main titanium surface coloring technologies include electroplating, anodizing, and electrostatic spraying. The electroplating method deposits metals or compounds of specific colors on the surface of titanium, while the anodizing process is to place titanium in an electrolyte. Under the action of an external voltage and current, an oxide film is formed on the surface, which presents different colors due to the interference effect of light. The electrostatic spraying method uses the principle of high-voltage static electricity to deposit a firmly attached and colorful film on the surface, but there is a risk of high-voltage electric shock during the process. The electroplating method and anodizing method produce waste liquid and waste gas, while the electrostatic spraying method produces powder and waste gas, which are harmful to the human body and the environment and do not meet the requirements of green environmental protection.

[0003] With the widespread application of titanium and titanium alloy materials in the civilian market, the decorative coating process on their surface has also attracted widespread attention. At present, the surface decorative coating technology of titanium is mainly traditional processes such as anodizing, electrostatic spraying and electroplating. First, a thin film is deposited on the titanium surface through electroplating or anodizing process. The color of the film layer is affected by the process parameters such as electrolyte composition, concentration, temperature, current and voltage, as well as the matrix texture. The process stability is poor, the film layer has poor bonding with the matrix, and it is easy to fall off after long-term use. Secondly, the waste liquid and waste gas generated by anodizing, electrostatic spraying, electroplating and other processes are harmful to human health and the environment, and do not meet the requirements of green, low-carbon and environmental protection. Finally, anodizing, electrostatic spraying and electroplating are suitable for the preparation of large-area decorative coatings, and cannot achieve the effect of fine color textures. Summary of the invention

[0004] The purpose of the present invention is to provide a method for laser-induced generation of color texture patterns on titanium surfaces, so as to solve the problem that the prior art cannot achieve the effect of fine color textures on titanium surfaces.

[0005] The present invention adopts the following technical solution: a method for laser-induced generation of a color texture pattern on a titanium surface, comprising:

[0006] Step 1: Grind, polish and clean the titanium alloy surface, draw a pattern on the titanium alloy surface using a laser, and continuously adjust the laser parameters until a processing database that correlates the laser parameters with the color of the titanium alloy surface pattern is obtained;

[0007] Step 2: Use a colorimeter to measure and calibrate the color of the pre-drawn pattern using the Lab value, and calculate the color difference between the color of the pre-drawn pattern and the colors in the processing database. When the color difference is ≤ the predetermined value, select the laser parameters corresponding to the corresponding color for processing.

[0008] Furthermore, when the color difference in step 2 is greater than the predetermined value, two colors closest to the pre-drawn pattern color are selected from the processing database, and the median values ​​of the laser processing parameters corresponding to the two colors are calculated, and the obtained median value is used for processing.

[0009] Further, the predetermined value in step 2 is 6.

[0010] Furthermore, the parameters of the laser in step 1 are specifically:

[0011] The wavelength is 1064nm, the laser spot size is A=φ50μm, the laser parameter pulse width is τ=4ns, the pulse repetition frequency is f=300KHz, the laser power is P=2~20W, the scanning speed is υ=50~500mm / s, and the scanning spacing is w=2~15μm.

[0012] Furthermore, after the titanium alloy surface is ground and polished in step 1, the roughness of the titanium alloy surface is Ra≤0.4.

[0013] The beneficial effects of the present invention are:

[0014] The present invention uses a laser heat source with adjustable pulse width to induce the formation of oxide films of different thicknesses and types on the titanium surface. The film presents different colors through the interference, reflection and absorption of light. The spot size is adjusted, the scanning speed is controlled, and a high-speed galvanometer scanning system is used to realize the preparation of various fine patterns.

[0015] The laser in the present invention acts on the titanium surface to generate an oxide film, which has good bonding strength with the substrate and is not easy to peel off after long-term use. Compared with the prior art, laser processing is non-contact processing, the process operation is simple, green and pollution-free, and fine texture processing can be achieved;

[0016] The present invention selects a MOPA laser, solidifies the pulse width and pulse repetition frequency, adjusts process parameters such as laser processing power, scanning speed and scanning spacing, obtains a color card library corresponding to processing parameters and color values, that is, obtains a processing database, and obtains the parameters of the laser during pattern processing by comparing the color values ​​of pre-processed patterns, calculating and analyzing the color difference, thereby improving the restoration degree and processing efficiency of the pre-processed patterns. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The pattern drawn in Example 1 of the present invention;

[0018] Figure 2 The colors of the oxide films obtained by using different parameters of the laser obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] The invention discloses a method for laser-induced generation of a color texture pattern on a titanium surface, comprising:

[0021] Step 1: Grind, polish and clean the titanium alloy surface, use a laser to draw a pattern on the titanium alloy surface, and continuously adjust the laser parameters until a processing database that correlates the laser parameters with the color of the titanium alloy surface pattern is obtained.

[0022] The parameters of the laser in step 1 are as follows: wavelength of 1064 nm, laser spot size of A = φ50 μm, laser parameter pulse width of τ = 4 ns, pulse repetition frequency of f = 300 KHz, laser power of P = 2 to 20 W, scanning speed of υ = 50 to 500 mm / s, and scanning spacing of w = 2 to 15 μm. After the titanium alloy surface is polished in step 1, the roughness of the titanium alloy surface is Ra≤0.4.

[0023] The titanium alloy sample was polished with 800#, 1000#, 1200#, 1500#, and 2000# sandpaper in turn, and then ground and polished to a surface roughness of Ra≤0.4, and then ultrasonically cleaned in acetone, deionized water, and anhydrous ethanol for 8 to 15 minutes each, and quickly dried to obtain a titanium alloy substrate for the test;

[0024] A MOPA nanosecond light laser with a wavelength of 1064nm is used, the laser spot size is A=φ50μm, the laser parameter pulse width is set to τ=4ns, the pulse repetition frequency is f=300KHz, and a rectangular pattern with a size of 10mm×10mm is drawn on the titanium alloy substrate by adjusting the laser power P=2~20W, the scanning speed υ=50~500mm / s, and the scanning spacing w=2~15μm.

[0025] For the rectangular pattern obtained above, the CIE Lab color space is selected to evaluate the color, the Lab of the rectangular pattern is matched with the parameters of the laser, and a laser processing database is established.

[0026] (P′ 1 υ′ 1 w′ 1 )—(L′ 1 a′ 1 b′ 1 )……(P′ k υ′ k w′k )—(L′ k a′ k b′ k )

[0027] Step 2: Use a colorimeter to measure and calibrate the color of the pre-drawn pattern using the Lab value, and calculate the color difference between the color of the pre-drawn pattern and the colors in the processing database. When the color difference is ≤ the predetermined value, select the laser parameters corresponding to the corresponding color for processing.

[0028] When the color difference in step 2 is greater than the predetermined value, two colors closest to the pre-drawn pattern color are selected from the processing database, and the median values ​​of the laser processing parameters corresponding to the two colors are calculated, and the processing is performed using the obtained median value. Among them, the predetermined value in step 2 is 6.

[0029] Select a pre-drawn pattern, use CIE Lab color space to calibrate the pattern color, and obtain the Lab value (L 1 a 1 b 1 )……(L k a k b k ); at the same time, the color difference △E value is calculated using the formula.

[0030]

[0031] When △E≤6, it means the color difference is not big and visually acceptable, and the processing parameters of the laser corresponding to the processing database are selected;

[0032] When △E>6, the surface color difference is large and visually unacceptable. The processing parameters of the laser corresponding to the two color values ​​adjacent to the pre-processing color value are selected in the processing database, and the median is calculated. Finally, the median is used to perform laser processing and drawing of the pattern on the titanium alloy substrate.

[0033] Example 1

[0034] The TA2 titanium sample was polished with 800#, 1000#, 1200#, 1500#, and 2000# sandpaper in turn, and then ground and polished to a surface roughness Ra of 0.32. It was then ultrasonically cleaned in acetone, deionized water, and anhydrous ethanol for 10 minutes each, and quickly dried to obtain the TA2 titanium substrate for the test.

[0035] A MOPA nanosecond laser with a wavelength of 1064nm is used, the laser spot size is A = φ50μm, the laser parameters are set to pulse width τ = 4ns, and the pulse repetition frequency is f = 300KHz:

[0036] The first adjustment was: laser power P = 10 W, scanning spacing w = 5 μm. The scanning speed υ was adjusted to 50, 100, 150, 200, 250, 300, 350, 400, 450, and 500 mm / s, respectively. A 10 mm × 10 mm rectangle was laser scanned on the TA2 titanium substrate, and the color value presented was calibrated using the CIE Lab value.

[0037] The second adjustment was: laser power P was 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 W, scanning speed υ = 200 mm / s, scanning spacing w = 10 μm, and a 10 mm × 10 mm rectangle was laser scanned on the TA2 titanium substrate, and the color value presented was calibrated using the CIE Lab value.

[0038] The second adjustment was: laser power P = 8 W, scanning speed υ = 300 mm / s, laser scanning intervals w were 2, 4, 6, 8, 10, 12, and 14 μm respectively, and a 10 mm × 10 mm rectangle was laser scanned on the TA2 titanium substrate, and the color values ​​presented were calibrated using CIELab values.

[0039] The laser processing parameters obtained above correspond to the oxide film color Lab, and a database is established, as shown in Table 1. The oxide film color obtained by the processing parameters corresponding to each serial number is as follows: Figure 2 shown.

[0040] Table 1 Laser processing parameters and oxide film color Lab value database

[0041]

[0042]

[0043] Select the pre-drawn pattern and calibrate the color of the pattern using the CIE Lab color space:

[0044] When the Lab value of a part of the color of the pattern is obtained, 1 , a 1 , b 1 )=(43,6,42), and the color card library (L′) in Table 1 23 , a′ 23 , b′ 23 )=(46,7,46), and the color difference △E value is calculated using the formula:

[0045]

[0046] When the Lab value of another part of the color of the pattern is obtained, 2 , a 2 , b 2)=(18,-23,-15), and the color card library (L′) in Table 1 1 , a′ 1 , b′ 1 )=(14,-28,-21),(L′ 2 , a′ 2 , b′ 2 )=(24, -20, -3), similar, use the formula to calculate the color difference △E value:

[0047]

[0048] When △E<6, visually acceptable, the color card library (L 1 , a 1 , b 1 )=(35, 18, -65) corresponding laser processing parameters (P=8W, w=6μm, υ=300mm / s) are used for texture pattern processing.

[0049] When △E>6, the visual is unacceptable. The laser processing parameters corresponding to the two color values ​​adjacent to the pre-processing color value are selected in the processing database, and the median is calculated. Finally, the laser processing and drawing of the pattern on the titanium alloy substrate is performed using the median. This is repeated until the pattern is drawn. The drawing result is shown in FIG. Figure 1 shown.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for laser-induced color texture pattern on titanium surface, characterized in that: include: Step 1: Grind, polish and clean the titanium alloy surface, draw a pattern on the titanium alloy surface using a laser, and continuously adjust the laser parameters until a processing database that correlates the laser parameters with the color of the titanium alloy surface pattern is obtained; Step 2: Use a colorimeter to measure and calibrate the color of the pre-drawn pattern using the Lab value, and calculate the color difference between the color of the pre-drawn pattern and the colors in the processing database. When the color difference is ≤ the predetermined value, select the laser parameters corresponding to the corresponding color for processing.

2. The method of laser inducing a color texture pattern on a titanium surface according to claim 1, characterized in that: When the color difference in step 2 is greater than the predetermined value, two colors closest to the pre-drawn pattern color are selected from the processing database, and the median values ​​of the laser processing parameters corresponding to the two colors are calculated, and the obtained median value is used for processing.

3. The method for laser inducing a color texture pattern on a titanium surface according to claim 1 or 2, characterized in that: The predetermined value in step 2 is 6.

4. The method of laser inducing a color texture pattern on a titanium surface according to claim 1, characterized in that: The parameters of the laser in step 1 are specifically: The wavelength is 1064nm, the laser spot size is A=φ50μm, the laser parameter pulse width is τ=4ns, the pulse repetition frequency is f=300KHz, the laser power is P=2~20W, the scanning speed is υ=50~500mm / s, and the scanning spacing is w=2~15μm.

5. The method of laser inducing color texture pattern on titanium surface according to claim 1, characterized in that: After the titanium alloy surface is ground and polished in step 1, the roughness of the titanium alloy surface is Ra≤0.4.

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