A method for improving the color uniformity of an anodic oxidation film layer on a titanium crystal flower surface

Abstract

The application discloses a method for improving color uniformity of an anodic oxidation film layer on a titanium crystal flower surface, relates to the field of titanium and titanium alloy surface treatment, and aims at the problem of color unevenness caused by the inconsistent local film forming rate and uneven film thickness of the titanium crystal flower surface due to the grain orientation difference. The method comprises the following steps: S1, providing a titanium crystal flower product; S2, placing the titanium crystal flower product in an acid electrolyte to perform first-step anodic oxidation; and S3, after the first-step anodic oxidation, re-clamping the titanium crystal flower product to perform second-step anodic oxidation. The method does not need to perform complicated modification on the existing anodic oxidation equipment, nor needs to introduce an external additive, and can effectively improve the color consistency of the anodic oxidation film layer on the titanium crystal flower surface by optimizing a voltage application path, and is suitable for industrial application.

Description

Technical Field

[0001] This invention relates to the field of titanium and titanium alloy surface treatment technology, and in particular to a method for improving the color uniformity of the anodic oxide film layer on the surface of titanium crystal flowers. Background Technology

[0002] Titanium and titanium alloys are widely used in aerospace, medical devices, chemical equipment, and architectural decoration due to their advantages such as low density, high specific strength, excellent corrosion resistance, and good biocompatibility. In recent years, with increasing demands for aesthetic appeal in materials, decorative surface treatment technologies for titanium and titanium alloy products have received growing attention. Through heat treatment at temperatures above the phase transformation point, titanium and titanium alloy surfaces can form titanium flower structures with specific microstructures. This structure, composed of grains with different orientations, can create rich interference color effects during anodizing, thus giving the products a unique visual aesthetic and high decorative application value.

[0003] Anodizing is a common method for coloring the surface of titanium and titanium alloys. Its coloring principle mainly relies on the interference effect of the oxide film thickness on incident light. Different thicknesses correspond to different interference colors, thus a variety of colors can be obtained by controlling the oxidation process parameters. However, for surfaces with titanium grain structures, the electrochemical behavior of different grain orientations varies, resulting in differences in local resistance, breakdown potential, and film formation rate, leading to uneven film growth during anodizing. Regions with favorable orientations form films faster and thicker, while regions with unfavorable orientations form films slower and thinner. This difference in film thickness manifests as macroscopic color unevenness under light interference, severely affecting the appearance consistency and decorative effect of the product.

[0004] Existing technologies have yielded some research on the preparation of colored anodic oxide films on titanium crystal flower surfaces. Chinese invention patent CN115537895A discloses a method for preparing a dazzling colored anodic oxide film on a pure titanium surface. This method involves polishing and vacuum annealing pure titanium to obtain a titanium crystal flower structure, followed by anodizing in a glucose solution containing graphene nanosheets using a constant current mode, supplemented by ultrasonic stirring, to finally obtain a dazzling colored film layer. While this method can prepare colored films with strong visual effects, its dazzling effect largely depends on the local potential differences caused by different grain orientations of the titanium crystal flowers. These differences lead to uneven anodic oxide film thickness and variations in optical interference. Furthermore, the process time window for the same color system is narrow under constant current mode, making it difficult to control process stability and batch consistency. The introduction of graphene nanosheets also increases process cost and complexity.

[0005] Another Chinese invention patent, CN117552067A, discloses a gradient coloring process for anodizing titanium and titanium alloys. This method achieves a gradient color effect on the surface of titanium alloys by controlling the immersion depth, pull-out speed, and output voltage variations of the workpiece. This solution is suitable for preparing gradient color films, but it does not address the problem of inconsistent film formation rates on the surface of titanium crystal flowers due to differences in grain orientation. Therefore, it is still insufficiently targeted at improving the color uniformity of the anodized film on the surface of titanium crystal flowers, and it is difficult to solve the uneven film thickness and color differences caused by grain orientation heterogeneity.

[0006] In summary, existing technologies for addressing the issue of color uniformity in anodized titanium crystal flower surfaces suffer from drawbacks such as complex processes, high costs, or a lack of specificity. Therefore, improving the color uniformity of the anodized film on titanium crystal flower surfaces without significantly increasing process complexity or altering existing electrolyte systems and equipment conditions has become a pressing technical problem to be solved in this field. Summary of the Invention

[0007] This invention overcomes the shortcomings of the prior art and provides a method for improving the color uniformity of the anodic oxide film on the surface of titanium crystal flowers. This method does not require complex modifications to existing anodizing equipment or the introduction of exogenous additives. By optimizing the voltage application path, the color consistency of the anodic oxide film on the surface of titanium crystal flowers can be effectively improved, making it suitable for industrial applications.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention provides a method for improving the color uniformity of the anodic oxide film layer on the surface of titanium crystal flowers, comprising the following steps:

[0009] S1. Provide a titanium crystal flower product; the titanium crystal flower product is a product in which titanium or titanium alloy products are heat-treated at a temperature higher than the phase transformation point to form a titanium crystal flower structure on the surface.

[0010] S2. The titanium crystal flower product is placed in an acidic electrolyte for the first step of anodizing; the first step of anodizing adopts a constant voltage mode, and the oxidation voltage is the main oxidation voltage corresponding to the target color;

[0011] S3. After the first step of anodizing, the titanium crystal flower product is re-clamped and subjected to the second step of anodizing; the voltage of the second step of anodizing is increased or decreased by 1-3 V compared with the voltage of the first step of anodizing.

[0012] In a preferred embodiment of the present invention, the acid electrolyte is at least one of phosphoric acid, sulfuric acid, oxalic acid, citric acid, or a combination thereof.

[0013] In a preferred embodiment of the present invention, the acid electrolyte is phosphoric acid with a concentration of 0.5-1.0 mol / L.

[0014] In a preferred embodiment of the present invention, the voltage range of the first step of anodizing is 40-120 V, and the oxidation time is 30-60 s.

[0015] In a preferred embodiment of the present invention, the oxidation time of the second step of anodizing is 10-30 s.

[0016] In a preferred embodiment of the present invention, the electrolyte temperature is 15-30 °C during the first and second anodizing processes.

[0017] In a preferred embodiment of the present invention, the fixture or clamping part in contact with the workpiece used in the anodizing process of the titanium crystal flower product is made of titanium.

[0018] In a preferred embodiment of the present invention, the voltage combination of the first step anodizing and the second step anodizing is selected from one of the following: 50 V and 52 V, 70 V and 68 V, 90 V and 91 V, 110 V and 107 V, 50 V and 48 V.

[0019] In a preferred embodiment of the present invention, after the second step of anodizing, the method further includes the steps of rinsing and drying the resulting product with water.

[0020] In a preferred embodiment of the present invention, the average crystal size on the surface of the titanium crystal flower product is 0.5-25 mm.

[0021] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0022] (1) This invention provides a method for improving the color uniformity of the anodic oxide film on the surface of titanium crystal flowers. It adopts a step-by-step gradient voltage anodic oxidation process. Based on the self-adjustment mechanism of local impedance difference, the film thickness that was originally very different on different grain orientations can gradually converge and become uniform. This invention cleverly utilizes the impedance characteristics of the film itself for feedback adjustment. Without introducing external materials or modifying the equipment, it fundamentally solves the problem of uneven film thickness caused by grain orientation difference, thereby effectively eliminating macroscopic interference color difference and improving the appearance quality of titanium crystal flower products.

[0023] (2) By controlling the range of voltage variation in the second step, the present invention performs secondary oxidation under a small voltage gradient, which can precisely control the degree of compensatory growth and avoid the overall thickness of the film layer from crossing to the optical thickness range corresponding to another interference color. The growth of the titanium oxide film follows the electric field-assisted ion migration mechanism. The small change in voltage is only enough to activate the active sites in the thin area that have not been completely passivated, but not enough to change the stable film structure that has been formed in the thick area. Thus, while improving the color uniformity, the target hue determined by the first step of oxidation is perfectly preserved. Compared with the existing technology, which has to adjust the overall process parameters in order to pursue uniformity, resulting in hue drift, the present invention achieves a balance between uniformity and hue stability, so that the same voltage combination can repeatedly obtain a stable color effect, which is conducive to maintaining the stability and repeatability of the target color system.

[0024] (3) The second oxidation step of the present invention can change the path distribution of the current on the sample surface by re-clamping the sample, so that the electric field line of the second oxidation is different from that of the first oxidation. The slight change in the direction of the electric field helps to break the directional ion migration channel that may be formed in the first oxidation process, and promotes the redistribution of charge on the surface of the film layer. This alleviates the area that was originally too thick due to the concentration of electric field, while the thin area that was originally at the edge of the electric field gets more opportunities to form a film. As a result, the film thickness distribution on the two-dimensional plane is more diffuse and uniform, which can more comprehensively deal with the anisotropic electrochemical behavior under the complex grain orientation of titanium crystal flowers, thereby further improving the color consistency on large-area workpieces.

[0025] (4) Since the process method of the present invention does not require the addition of nanomaterials such as graphene or changes to the basic composition of the electrolyte, the entire anodizing process maintains the economy and stability of the traditional phosphoric acid system. The pure electrolyte environment avoids interference from foreign particles on the film formation process. The growth of the film is completely dominated by the interaction between the titanium substrate and the electric field, making the effect of voltage fine-tuning in the second step more pure and controllable, thereby reducing the number of process control variables and improving the production tolerance. The present invention can be implemented on conventional industrial anodizing lines without the need for expensive equipment modification or consumable investment, effectively reducing the threshold for large-scale application. At the same time, due to the purity of the film, its corrosion resistance and mechanical integrity are also well maintained. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1This is a schematic diagram illustrating the formation mechanism of uneven color in the anodic oxide film layer on the surface of titanium crystal flowers under conventional anodizing processes;

[0028] Figure 2 This is a schematic diagram illustrating the mechanism by which the stepwise gradient anodizing process of the present invention improves the color uniformity of the anodized film on the surface of titanium crystal flowers;

[0029] Figure 3 This is a macroscopic view of the 50 V + 52 V gradient anodic oxide film obtained in Example 1 of the present invention;

[0030] Figure 4 This is a macroscopic view of the 70 V + 68 V gradient anodic oxide film obtained in Example 2 of the present invention;

[0031] Figure 5 This is a macroscopic view of the 90 V+91 V gradient anodic oxide film obtained in Example 3 of the present invention;

[0032] Figure 6 This is a macroscopic view of the 110 V + 107 V gradient anodic oxide film obtained in Example 4 of the present invention;

[0033] Figure 7 This is a macroscopic view of the 50 V + 48 V gradient anodic oxide film obtained in Example 5 of the present invention;

[0034] Figure 8 This is a macroscopic view of the 50 V + 52 V gradient anodic oxide film obtained in Example 6 of the present invention;

[0035] Figure 9 This is a macroscopic view of the 50 V anodic oxide film obtained in Comparative Example 1 of this invention;

[0036] Figure 10 This is a macroscopic view of the 70 V anodic oxide film obtained in Comparative Example 2 of the present invention;

[0037] Figure 11 This is a macroscopic view of the 90 V anodic oxide film obtained in Comparative Example 3 of the present invention;

[0038] Figure 12 This is a macroscopic view of the 110 V anodic oxide film obtained in Comparative Example 4 of the present invention;

[0039] Figure 13 This is a macroscopic view of the 50 V anodic oxide film obtained in Comparative Example 5 of the present invention;

[0040] Figure 14 This is a comparison diagram of the overall color difference ΔE and brightness difference ΔL of the films obtained in Examples 1-4 and Comparative Examples 1-4 of the present invention. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0043] Application Overview:

[0044] The core of this invention lies in compensating for the localized film thickness differences formed after the first anodizing process through a stepwise gradient voltage anodizing strategy, without altering the chemical system or introducing exogenous elements. This achieves convergence in film thickness distribution and improves macroscopic color uniformity. When titanium and titanium alloys are held at temperatures near or above their phase transformation points, a microstructure transformation occurs from primary α phase to β phase and then to secondary α phase, forming titanium flower structures on the material surface. Due to the variant selection effect during the β-phase to secondary α-phase transformation, the grain orientations in different regions within the titanium flower exhibit diversity. This orientation difference further leads to differences in local potential, resistance, and electrochemical reactivity.

[0045] In conventional constant-voltage anodizing, discharge breakdown and rapid nucleation / thickness formation are primarily influenced by the significant resistivity difference between the substrate metal Ti and the newly formed TiO2 film. In the presence of grain orientation heterogeneity, regions with relatively better conductivity are more likely to experience localized breakdown and form thicker films, while regions with relatively higher resistivity experience slower film formation, resulting in thinner films. As the oxidation process continues, the thickness difference between the initial thick and thin regions is retained and further amplified, ultimately manifesting as significant interference color inhomogeneity. Figure 1 ).

[0046] Based on the above understanding, this invention proposes a stepwise gradient anodizing strategy. After completing the first step of constant-voltage anodizing, the sample is re-clamped to perform the second step of anodizing, with the voltage of the second anodizing step varying by only 1-3 V compared to the first. This small voltage change does not involve simple repetitive oxidation of the film layer, but rather utilizes the local impedance difference already formed after the first oxidation to make the thinner areas of the film layer more prone to further breakdown and compensatory thickening during the second oxidation step, while the continued growth of the thicker areas of the film layer is relatively limited. Figure 2 ).

[0047] As a result, the film thickness in different regions tends to be similar, thereby improving the overall uniformity of the film color. Furthermore, the voltage change in the second step is controlled within 1-3 V, which effectively improves the growth conditions in locally thin areas and minimizes the possibility of the overall optical thickness of the film crossing new interference color ranges. Thus, the second oxidation step primarily serves a homogenization correction function rather than significantly altering the original hue. Therefore, the essence of this invention is not simply to pursue a thicker oxide film, but rather to achieve optimized film thickness distribution and improved macroscopic color uniformity through localized compensatory growth induced by a finite voltage gradient.

[0048] It should be noted that the raw materials, equipment and reagents used in this invention can all be purchased from the market or obtained through existing preparation methods.

[0049] To further simplify and make the present invention achieve its objectives and effects, the present invention will be further illustrated in conjunction with the following specific embodiments and comparative examples, but the present invention is not limited to the scope of the embodiments described herein.

[0050] It should be noted that, unless otherwise stated, the samples used in the following examples and comparative examples are all titanium crystal flower plates with dimensions of 0.5 mm × 50 mm × 100 mm and a titanium content ≥ 99 wt%. The average crystal flower size on the surface of the titanium crystal flower plate is approximately 0.8 mm and 3 mm. The anodic oxidation electrolyte is a phosphoric acid electrolyte with a concentration of 1.0 mol / L, and the oxidation temperature is controlled at 20 °C.

[0051] Example 1:

[0052] This embodiment employs a step-by-step gradient anodizing process to prepare a uniformly colored anodized film on the surface of a titanium crystal flower plate, including the following steps:

[0053] S1. Place the titanium crystal flower plate with an average crystal flower size of 0.8 mm in a phosphoric acid electrolyte with a concentration of 1.0 mol / L and perform constant voltage anodizing at 20 ℃. The first step of anodizing voltage is 50 V and the oxidation time is 60 s.

[0054] S2. After the first step of anodizing, the sample is removed and re-clamped with the anodizing clamp before the second step of anodizing is performed. When re-clamping, the clamping part is located in the area where a complete anodized film has been formed. The voltage for the second step of anodizing is 52 V and the oxidation time is 20 s.

[0055] After the above-described stepwise gradient anodizing treatment, a relatively uniform yellow anodized film layer is formed on the surface of the resulting titanium crystal flower plate, and its macroscopic morphology is as follows: Figure 3 As shown.

[0056] Example 2:

[0057] This embodiment employs a step-by-step gradient anodizing process to prepare a uniformly colored anodized film on the surface of a titanium crystal flower plate, including the following steps:

[0058] S1. Place a titanium plate with an average crystal size of 0.8 mm in a phosphoric acid electrolyte with a concentration of 1.0 mol / L. Under the condition of 20℃, the first step of anodic oxidation voltage is 70 V and the oxidation time is 60 s.

[0059] S2. After the first step of anodizing, the sample is removed and re-clamped with the anodizing clamp before the second step of anodizing is performed. When re-clamping, the clamping part is located in the area where a complete anodized film has been formed. The voltage for the second step of anodizing is 68 V and the oxidation time is 15 s.

[0060] After the above gradient anodizing treatment, the anodic oxide film prepared by the titanium crystal flower plate in this embodiment is as follows: Figure 4 As shown, a uniform purple anodic oxide film was prepared on the surface of the titanium crystal flower plate.

[0061] Example 3:

[0062] This embodiment employs a step-by-step gradient anodizing process to prepare a uniformly colored anodized film on the surface of a titanium crystal flower plate, including the following steps:

[0063] S1. Place the titanium crystal flower plate with an average crystal flower size of 0.8 mm in a phosphoric acid electrolyte with a concentration of 1.0 mol / L and perform constant voltage anodizing at 20 ℃. The first step of anodizing voltage is 90 V and the oxidation time is 60 s.

[0064] S2. After the first step of anodizing, the sample is removed and re-clamped with the anodizing clamp before the second step of anodizing is performed. When re-clamping, the clamping part is located in the area where a complete anodized film has been formed. The voltage for the second step of anodizing is 91 V and the oxidation time is 15 s.

[0065] After the above gradient anodizing treatment, a relatively uniform blue anodized film layer is formed on the surface of the obtained titanium crystal flower plate, and its macroscopic morphology is as follows. Figure 5 As shown.

[0066] Example 4:

[0067] This embodiment employs a step-by-step gradient anodizing process to prepare a uniformly colored anodized film on the surface of a titanium crystal flower plate, including the following steps:

[0068] S1. Place the titanium crystal flower plate with an average crystal flower size of 0.8 mm in a phosphoric acid electrolyte with a concentration of 1.0 mol / L and perform constant voltage anodizing at 20 ℃. The first step of anodizing voltage is 110 V and the oxidation time is 60 s.

[0069] S2. After the first step of anodizing, the sample is removed and re-clamped with the anodizing clamp before the second step of anodizing is performed. When re-clamping, the clamping part is located in the area where a complete anodized film has been formed. The voltage for the second step of anodizing is 107 V and the oxidation time is 10 s.

[0070] After the above gradient anodizing treatment, a relatively uniform gray anodized film layer is formed on the surface of the obtained titanium crystal flower plate, and its macroscopic morphology is as follows: Figure 6 As shown.

[0071] Example 5:

[0072] This embodiment employs a step-by-step gradient anodizing process to prepare a uniformly colored anodized film on the surface of a titanium crystal flower plate, including the following steps:

[0073] S1. Place the titanium crystal flower plate with an average crystal flower size of 8.99 mm in a phosphoric acid electrolyte with a concentration of 1.0 mol / L and perform constant voltage anodizing at 20 ℃. The first step of anodizing voltage is 50 V and the oxidation time is 60 s.

[0074] S2. After the first step of anodizing, the sample is removed and re-clamped with the anodizing clamp before the second step of anodizing is performed. When re-clamping, the clamping part is located in the area where a complete anodized film has been formed. The voltage for the second step of anodizing is 48 V and the oxidation time is 30 s.

[0075] After the above gradient anodizing treatment, a relatively uniform yellow anodized film layer is formed on the surface of the obtained titanium crystal flower plate, and its macroscopic morphology is as follows. Figure 7 As shown.

[0076] Example 6:

[0077] This embodiment employs a step-by-step gradient anodizing process to prepare a uniformly colored anodized film on the surface of a titanium crystal flower plate, including the following steps:

[0078] S1. Place the titanium crystal flower plate with an average crystal flower size of 22.04 mm in a phosphoric acid electrolyte with a concentration of 1.0 mol / L and perform constant voltage anodizing at 20 ℃. The first step of anodizing voltage is 50 V and the oxidation time is 60 s.

[0079] S2. After the first step of anodizing, the sample is removed and re-clamped with the anodizing clamp before the second step of anodizing is performed. When re-clamping, the clamping part is located in the area where a complete anodized film has been formed. The voltage for the second step of anodizing is 52 V and the oxidation time is 30 s.

[0080] After the above gradient anodizing treatment, a relatively uniform yellow anodized film layer is formed on the surface of the obtained titanium crystal flower plate, and its macroscopic morphology is as follows. Figure 8 As shown.

[0081] Comparative Example 1:

[0082] This comparative example is basically the same as Example 1, except that: the titanium crystal flower plate with the same specifications and structure as in Example 1 is placed in a phosphoric acid electrolyte with a concentration of 1.0 mol / L and subjected to a single constant voltage anodizing at 20 °C. The anodizing voltage is 50 V and the oxidation time is 60 s. The second step of gradient anodizing treatment is not performed.

[0083] A yellow anodic oxide film was formed on the surface of the obtained sample, but the macroscopic color uniformity of the film was poor, with obvious color differences in local areas. Its macroscopic morphology is as follows: Figure 9 As shown.

[0084] Comparative Example 2:

[0085] This comparative example is basically the same as Example 2, except that: the titanium crystal flower plate with the same specifications and structure as in Example 2 was placed in a phosphoric acid electrolyte with a concentration of 1.0 mol / L and subjected to a single constant voltage anodizing at 20 °C. The anodizing voltage was 70 V and the oxidation time was 60 s. The second step of gradient anodizing was not performed.

[0086] A purple anodic oxide film was formed on the surface of the obtained sample, but the macroscopic color uniformity of the film was poor, with obvious color differences in local areas. Its macroscopic morphology is as follows: Figure 10 As shown.

[0087] Comparative Example 3:

[0088] This comparative example is basically the same as Example 3, except that: the titanium crystal flower plate with the same specifications and structure as in Example 3 is placed in a phosphoric acid electrolyte with a concentration of 1.0 mol / L and subjected to a single constant voltage anodizing at 20 °C. The anodizing voltage is 90 V and the oxidation time is 60 s. The second step of gradient anodizing treatment is not performed.

[0089] A blue anodic oxide film was formed on the surface of the obtained sample, but the macroscopic color uniformity of the film was poor, with obvious color differences in local areas. Its macroscopic morphology is as follows: Figure 11 As shown.

[0090] Comparative Example 4:

[0091] This comparative example is basically the same as Example 4, except that: the titanium crystal flower plate with the same specifications and structure as in Example 4 is placed in a phosphoric acid electrolyte with a concentration of 1.0 mol / L and subjected to a single constant voltage anodizing at 20 °C. The anodizing voltage is 110 V and the oxidation time is 60 s. The second step of gradient anodizing treatment is not performed.

[0092] A gray anodic oxide film was formed on the surface of the obtained sample, but the macroscopic color uniformity of the film was poor, with obvious color differences in local areas. Its macroscopic morphology is as follows: Figure 12 As shown.

[0093] Comparative Example 5:

[0094] This comparative example is basically the same as Example 5, except that: the titanium crystal flower plate with the same specifications and structure as in Example 5 is placed in a phosphoric acid electrolyte with a concentration of 1.0 mol / L and subjected to a single constant voltage anodizing at 20 °C. The anodizing voltage is 50 V and the oxidation time is 60 s. The second step of gradient anodizing treatment is not performed.

[0095] A yellow anodic oxide film was formed on the surface of the obtained sample, but the macroscopic color uniformity of the film was poor, with obvious color differences in local areas. Its macroscopic morphology is as follows: Figure 13 As shown.

[0096] from Figure 14 The comparison results of the overall color difference ΔE and brightness difference ΔL of the films obtained in Examples 1-4 and Comparative Examples 1-4 show that the method of the present invention has obvious advantages in improving the color uniformity of the anodic oxide film on the surface of titanium crystal flowers. Figure 14 In (a), the ΔE values ​​corresponding to the embodiments of the present invention remain in a low range under different voltages, such as approximately 0.7 at 50 V, approximately 1.2 at 70 V, approximately 1.0 at 90 V, and approximately 0.7 at 110 V; while the ΔE values ​​corresponding to the comparative examples are generally higher, approximately 4.0, 6.5, 4.0, and 2.0 at the corresponding voltages, respectively. This indicates that the present invention, through stepwise gradient voltage anodizing, effectively suppresses the film thickness unevenness caused by differences in grain orientation, making the interference colors of the film layers more uniform and significantly reducing color difference. Figure 14 (b) The brightness difference ΔL also confirms the effect of the present invention. The ΔL value of the embodiment of the present invention changes relatively smoothly under different voltages, and remains between 58 and 71 in the range of 50 V-110 V, while the ΔL value of the comparative example fluctuates more and deviates from the ideal range under some voltages.

[0097] comprehensive Figure 14 (a) and Figure 14As can be seen from the data in (b), the method of the present invention significantly improves the uniformity of film color and brightness while ensuring the stability of the target hue, effectively solving the problem of uneven color of the anodic oxide film on the surface of titanium crystal flowers in the prior art, thus providing a reliable technical solution for industrial application.

[0098] The above description is based on the preferred embodiments of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the invention is defined by the appended claims rather than the foregoing description, and all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0099] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for improving the color uniformity of the anodic oxide film layer on the surface of titanium crystal flowers, characterized in that, Includes the following steps: S1. Provide a titanium crystal flower product; the titanium crystal flower product is a product in which titanium or titanium alloy products are heat-treated at a temperature higher than the phase transformation point to form a titanium crystal flower structure on the surface. S2. The titanium crystal flower product is placed in an acidic electrolyte for the first step of anodizing; the first step of anodizing adopts a constant voltage mode, and the oxidation voltage is the main oxidation voltage corresponding to the target color; S3. After the first step of anodizing, the titanium crystal flower product is re-clamped and subjected to the second step of anodizing; the voltage of the second step of anodizing is increased or decreased by 1-3 V compared with the voltage of the first step of anodizing.

2. The method for improving the color uniformity of the anodic oxide film layer on the surface of titanium crystal flowers according to claim 1, characterized in that: The acid electrolyte is at least one of phosphoric acid, sulfuric acid, oxalic acid, citric acid, or a combination thereof.

3. The method for improving the color uniformity of the anodic oxide film layer on the surface of titanium crystal flowers according to claim 2, characterized in that: The acid electrolyte is phosphoric acid with a concentration of 0.5-1.0 mol / L.

4. The method for improving the color uniformity of the anodic oxide film layer on the surface of titanium crystal flowers according to claim 1, characterized in that: The voltage range for the first step of anodizing is 40-120 V, and the oxidation time is 30-60 s.

5. The method for improving the color uniformity of the anodic oxide film layer on the surface of titanium crystal flowers according to claim 1, characterized in that: The oxidation time for the second step, anodizing, is 10-30 seconds.

6. The method for improving the color uniformity of the anodic oxide film layer on the surface of titanium crystal flowers according to claim 1, characterized in that: During the first and second anodizing processes, the electrolyte temperature is 15-30 ℃.

7. The method for improving the color uniformity of the anodic oxide film layer on the surface of titanium crystal flowers according to claim 1, characterized in that: The fixtures or clamping parts that come into contact with the workpiece used in the anodizing process of the titanium crystal flower product are made of titanium.

8. The method for improving the color uniformity of the anodic oxide film layer on the surface of titanium crystal flowers according to claim 1, characterized in that: The second step, after anodizing, also includes the steps of rinsing the resulting product with water and drying it.

9. The method for improving the color uniformity of the anodic oxide film layer on the surface of titanium crystal flowers according to claim 1, characterized in that: The average crystal size on the surface of the titanium crystal flower product is 0.5-25 mm.

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