Anodizing method suitable for titanium alloy cylindrical part

Abstract

The invention relates to an anodizing method suitable for a titanium alloy cylindrical part, belongs to the technical field of metal surface treatment, and solves at least one of the problems that an oxidation film formed by anodizing the titanium alloy cylindrical part is insufficient in density and hardness, is locally loosened and is easy to fall off and the like in the prior art. According to the anodizing method suitable for the titanium alloy cylindrical part, in the anodizing process, the titanium alloy cylindrical part continuously rotates in one direction along the axis in an anodizing solution, and the rotating linear speed and voltage are increased in a stepped mode. A surface oxidation film of the titanium alloy cylindrical part prepared through the method is high in compactness, the porosity is smaller than or equal to 24%, the hardness is high and ranges from 250 HV to 300 HV, the problem of local loosening and falling is almost avoided, the titanium alloy part has better wear resistance and anti-corrosion effect, according to testing of GB / T 10125-2021 Artificial Atmosphere Corrosion Test Salt Spray Test, after 500 hours of neutral salt spray test, the corrosion resistance of the titanium alloy cylindrical part is improved, and the corrosion resistance of the titanium alloy cylindrical part is improved. And the surface of the film layer has no corrosion sign.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal surface treatment, and particularly relates to an anodization method suitable for titanium alloy cylindrical parts. BACKGROUND

[0002] With the development of aerospace technology, large-size titanium alloy structures are increasingly widely used. In order to improve the wear resistance and corrosion resistance of titanium alloy parts, the titanium alloy parts often need to be subjected to anodic oxidation treatment.

[0003] The oxide film formed by the existing anodic oxidation treatment technology, especially the oxide film formed for the titanium alloy cylindrical parts, is prone to problems such as insufficient compactness, poor hardness, poor local adhesion and falling off, which seriously affects the wear resistance, corrosion resistance and service life of the titanium alloy parts. SUMMARY

[0004] In view of the above analysis, the embodiments of the present application aim to provide an anodization method suitable for titanium alloy cylindrical parts, to solve at least one of the problems of insufficient compactness and hardness of the oxide film formed by anodic oxidation of the titanium alloy cylindrical parts and local loose and easy to fall off.

[0005] The present application provides an anodization method suitable for titanium alloy cylindrical parts, in which the titanium alloy cylindrical part is continuously rotated along the axis in the anodic oxidation solution during the anodic oxidation process, and the linear rotation speed and the voltage are stepwise increased.

[0006] The anodization method specifically comprises the following steps:

[0007] S1 assembly: assembling the titanium alloy cylindrical part into a special anodization tool;

[0008] S2 oil removal: placing the assembled tool and the titanium alloy cylindrical part together in a chemical oil removal solution to perform oil removal operation;

[0009] S3 water washing and activation: after oil removal, the tool and the titanium alloy cylindrical part are subjected to one water washing, then placed in an activation solution for activation, and then subjected to two water washings;

[0010] S4 anodic oxidation: placing the tool and the titanium alloy cylindrical part after the second water washing in an anodic oxidation solution to perform anodic oxidation, in which the titanium alloy cylindrical part is continuously rotated along the axis in the anodic oxidation solution during the anodic oxidation process, and the linear rotation speed and the voltage are stepwise increased;

[0011] S5 post-treatment: after the anodic oxidation is completed, the tool and the titanium alloy cylindrical part are taken out and washed with water, then the titanium alloy cylindrical part is taken out and dried after water washing.

[0012] Specifically, the stepwise increase in step S4 includes two stages.

[0013] The first stage is that the rotating linear speed of the titanium alloy cylinder is 0.01-0.02 m / s, the temperature is 10-30 DEG C, the voltage is 15-18 V, and the duration T1 is 0.5-5 min.

[0014] The second stage is that the rotating linear speed of the titanium alloy cylinder is 0.03-0.05 m / s, the temperature is 10-30 DEG C, the voltage is 20-22 V, and the duration T2 is 10-15 min.

[0015] Specifically, the special tool for anodic oxidation comprises a support frame and a rotating assembly.

[0016] The rotating assembly is rotatably connected to the support frame.

[0017] The rotating assembly comprises a driving gear, a transmission shaft and a chuck, the driving gear is installed at one end of the transmission shaft, the chuck is installed at the other end of the transmission shaft, and the three are coaxially installed and can synchronously rotate; the chuck is used for clamping the titanium alloy cylinder.

[0018] Specifically, the chuck is detachably connected to the transmission shaft, and different sizes of chucks are selected according to the specifications of the titanium alloy cylinder.

[0019] Specifically, the specific composition of the chemical oil removal solution in step S2 is: Na3PO4 40-60 g / L, NaOH 40-60 g / L, Na2CO3 20-40 g / L, and Na2SO3 5-12 g / L; the oil removal temperature is 40-70 DEG C, and the time is 5-30 min.

[0020] Specifically, the specific composition of the activation solution in step S3 is: HF 30-50 g / L and HNO380-100 g / L.

[0021] Specifically, the activation condition in step S3 is that the activation temperature is room temperature, and the activation time is 5-10 s.

[0022] Preferably, the anodic oxidation solution in step S4 is H2SO4180-220 g / L, and the cathode is a lead plate.

[0023] The application also provides a special tool for anodic oxidation, which is used for implementing the anodization method.

[0024] The special tool comprises a support frame and a rotating assembly.

[0025] The rotating assembly is rotatably connected to the support frame.

[0026] The rotating assembly comprises a driving gear, a transmission shaft and a chuck, the driving gear is installed at one end of the transmission shaft, the chuck is installed at the other end of the transmission shaft, and the three are coaxially installed and can synchronously rotate; the chuck is used for clamping the titanium alloy cylindrical part.

[0027] The application also provides a titanium alloy cylindrical part with an oxide film formed by the anodizing method.

[0028] Compared with the prior art, the application can achieve at least one of the following beneficial effects:

[0029] 1. The anodized film prepared by the anodizing method has high hardness (250-300 HV) and high density, and the porosity is less than or equal to 24%, which is significantly lower than the porosity of the existing single sulfuric acid solution anodizing (the porosity in the prior art is about 35%), and almost no local loose / peeling defects occur. It can be predicted that when other anodizing solutions (such as a composite anodizing solution: phosphoric acid-sulfuric acid) are selected, the oxidation process proposed in the application can also obtain higher density improvement on the basis of the prior art.

[0030] The application effectively improves the uniformity and firmness of the oxide film by continuously rotating the titanium alloy cylindrical part along the axis in the anodizing solution in a unidirectional manner during the anodizing process, and increasing the linear velocity and voltage in steps. In the initial stage of anodizing, the activated titanium alloy surface directly contacts the anodizing solution and the following chemical reactions occur:

[0031] Ti + 2H2O → TiO2 + 4H + + 4e -

[0032] An oxide film is formed on the surface of the titanium alloy cylindrical part. If the rotation speed (linear velocity) is too fast at this time, it will lead to uneven and insufficient contact between the surface of the part and the solution, resulting in ineffective generation of the oxide film. Therefore, both the rotation speed and the rotation direction need to be strictly controlled, and the rotation direction should not be changed as much as possible during the anodizing process, because too high rotation speed or changing the rotation direction will lead to uncontrollable vortex, resulting in insufficient contact between the surface of the part and the anodizing solution. In this process, the oxide film will also be dissolved and regenerated to some extent, and this dissolution and regeneration process helps to form a more uniform and dense oxide film, and strict control of the rotation speed is also conducive to the occurrence of this dissolution and regeneration.

[0033] It is worth emphasizing that anodizing at a certain speed compared with static state can timely "wash away" the local loose oxide film, which may be caused by the presence of impurities on the surface or other reasons, and timely "washing away" the loose oxide film and exposing the activated surface for oxidation is conducive to the formation of a uniform and firm oxide layer.

[0034] Further, a lower voltage should be used in the initial stage of the formation of the oxide film to prevent the oxide film from thickening too quickly, resulting in a large difference in the thickness of the oxide film at different parts of the component.

[0035] After the surface of the component has initially formed an oxide film, the rotation speed and the voltage can be appropriately increased, on the one hand, to form the oxide film of the preset thickness more quickly (the growth rate of the oxide film slows down after the oxide film grows to a certain thickness), and on the other hand, to appropriately increase the “washing” intensity and more effectively remove the locally loose oxide film. The “washing” intensity is controlled at a lower level in the initial stage because the binding force of the initially formed qualified oxide film is also relatively weak. If high-speed rotation is performed at the beginning, the normal oxide film will also be washed away.

[0036] It is worth noting that the rotation speed control strictly requires linear speed because the diameters / radii of different cylindrical components are different, and the angular speed does not directly determine the speed of the relative movement between the surface of the cylindrical component and the anodizing solution.

[0037] It has been verified through experiments that the oxide film on the surface of the titanium alloy cylindrical component treated by the anodization method provided in the application is uniform and dense, and almost no structural defects and local looseness exist.

[0038] 2. The titanium alloy cylindrical component treated by the anodization method provided in the application has significantly improved wear resistance and corrosion resistance. According to GB / T 10125-2021 “Salt Spray Test for Artificial Atmosphere Corrosion Test”, no corrosion marks are observed on the surface of the film layer after 500 hours of neutral salt spray test.

[0039] The above technical solutions in the application can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the application will be described in the subsequent specification, and some advantages will become apparent from the specification or be understood through the implementation of the application. The purposes and other advantages of the application can be achieved and obtained from the contents specifically indicated in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0040] The accompanying drawings are included to provide a further understanding of the application and are incorporated herein and constitute a part of the application. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application. In the drawings:

[0041] Figure 1 Fig. 1 is a schematic view of a possible special tool structure for anodization.

[0042] Reference signs:

[0043] 1, support frame; 2, chuck; 3, transmission shaft; 4, drive gear. DETAILED DESCRIPTION

[0044] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which form a part of this application, and together with the description are used to explain the principles of the application, and to describe the best mode contemplated by the inventors for carrying out the application.

[0045] The present application provides an anodizing method for titanium alloy cylinder, in which the titanium alloy cylinder is continuously rotated along the axis in the anodizing solution during the anodizing process, and the linear rotating speed and the voltage are increased step by step.

[0046] The anodizing method specifically comprises the following steps:

[0047] S1 assembly: the titanium alloy cylinder is assembled on a special anodizing tool;

[0048] S2 oil removal: the assembled tool and the titanium alloy cylinder are placed in a chemical oil removal solution for oil removal operation;

[0049] S3 water washing and activation: the tool and the titanium alloy cylinder after oil removal are subjected to one-time water washing, then placed in an activation solution for activation, and subjected to two-time water washing;

[0050] S4 anodizing: the tool and the titanium alloy cylinder after two-time water washing are placed in an anodizing solution for anodizing, in which the titanium alloy cylinder is continuously rotated along the axis in the anodizing solution during the anodizing process, and the linear rotating speed and the voltage are increased step by step;

[0051] S5 post-treatment: after the anodizing is completed, the tool and the titanium alloy cylinder are taken out and subjected to water washing, then the titanium alloy cylinder is taken out and dried after water washing.

[0052] Specifically, the step S4 stepwise increase includes two stages.

[0053] In the first stage, the linear rotating speed of the titanium alloy cylinder is 0.01-0.02 m / s, the temperature is 10-30℃, the voltage is 15-18V, and the duration T1 is 0.5-5 min;

[0054] In the second stage, the linear rotating speed of the titanium alloy cylinder is 0.03-0.05 m / s, the temperature is 10-30℃, the voltage is 20-22V, and the duration T2 is 10-15 min.

[0055] The present application effectively improves the uniformity and firmness of the oxidation film by continuously rotating the titanium alloy cylinder along the axis in the anodizing solution during the anodizing process, and increasing the linear rotating speed and the voltage step by step. In the initial stage of anodizing, the activated titanium alloy surface directly contacts with the anodizing solution, and the following chemical reaction occurs:

[0056] Ti + 2H2O → TiO2+ 4H + + 4e -

[0057] When forming an oxide film on the surface of the titanium alloy cylinder, if the rotation speed (linear speed) is too fast, it will lead to uneven and insufficient contact between the surface of the part and the solution, resulting in ineffective generation of the oxide film. Therefore, both the rotation speed and the rotation direction need to be strictly controlled, and the rotation direction should not be changed during the anodizing process as much as possible, because both too fast rotation speed and changing the rotation direction will lead to uncontrollable vortex, resulting in insufficient contact between the surface of the part and the anodizing solution. During this process, the oxide film will also be accompanied by a certain degree of dissolution and regeneration, which helps to form a more uniform and dense oxide film, and strict control of the rotation speed is also conducive to the occurrence of such dissolution and regeneration.

[0058] It is worth emphasizing that, compared with the static state, anodizing at a certain rotation speed can timely "wash away" the locally loose oxide film, which may be caused by the presence of impurities on the surface or other reasons, and timely "washing away" the loose oxide film and exposing the activated surface for oxidation is conducive to the formation of a uniform and firm oxide layer.

[0059] After the surface of the part has initially formed an oxide film, the rotation speed can be appropriately increased and the voltage can be increased, on the one hand, to form an oxide film of a predetermined thickness faster (the growth rate of the oxide film slows down after growing to a certain thickness), and on the other hand, to appropriately increase the "washing" intensity to remove the locally loose oxide film. The reason why the "washing" intensity is controlled at a relatively low level in the initial stage is that the binding force of the initially formed qualified oxide film is also relatively weak, and if high-speed rotation is performed at the beginning, the normal oxide film will also be washed away.

[0060] It is worth mentioning that the rotation speed control strictly requires linear speed, because the diameters / radii of different cylinders are different, and the angular speed does not directly determine the speed of the relative movement between the surface of the cylinder and the anodizing solution.

[0061] Specifically, the special tool for anodizing includes a support frame and a rotating assembly;

[0062] The rotating assembly is rotatably connected to the support frame;

[0063] The rotating assembly includes a drive gear, a transmission shaft, and a chuck, the drive gear is installed at one end of the transmission shaft, the chuck is installed at the other end of the transmission shaft, and the three are coaxially installed and can synchronously rotate; the chuck is used to clamp the titanium alloy cylinder.

[0064] Specifically, the chuck is detachably connected to the transmission shaft, and different sizes of chucks are selected according to the specifications of the titanium alloy cylinder.

[0065] Specifically, the specific composition of the chemical oil removal solution in step S2 is: Na3PO4 40-60 g / L, NaOH 40-60 g / L, Na2CO3 20-40 g / L, and Na2SO3 5-12 g / L; the oil removal temperature is 40-70 DEG C, and the time is 5-30 min.

[0066] Specifically, the specific composition of the activation solution in step S3 is: HF 30-50 g / L and HNO380-100 g / L.

[0067] Specifically, the activation conditions in step S3 are: the activation temperature is room temperature, and the activation time is 5-10 s.

[0068] It is worth noting that the activation treatment can remove the natural oxide layer, oil stains, organic residues and other impurities on the surface of the titanium alloy. If these impurities are not removed, they will hinder the uniform growth of the oxide film during the anodization process, resulting in problems such as uneven film thickness and inconsistent color. For example, through pickling, the natural oxide layer and residual contaminants on the surface of the titanium alloy can be removed, and the surface can be etched to promote better adhesion of the newly formed oxide layer.

[0069] Further, the activation treatment can change the microstructure of the titanium alloy surface, making it rougher or forming a specific topography, thereby improving the adhesion and uniformity of the oxide film

[0070] Preferably, the anodization solution in step S4 is H2SO4 180-220 g / L, and the cathode is a lead plate.

[0071] The application also provides a special tool for anodization, which is used to implement the anodization method.

[0072] The special tool comprises a support frame and a rotating assembly.

[0073] The rotating assembly is rotatably connected to the support frame.

[0074] The rotating assembly comprises a drive gear, a transmission shaft and a chuck, the drive gear is installed at one end of the transmission shaft, the chuck is installed at the other end of the transmission shaft, and the three are coaxially installed and can rotate synchronously; the chuck is used to clamp the titanium alloy cylindrical part.

[0075] The application also provides a titanium alloy cylindrical part having an oxide film formed by the anodization method.

[0076] Further, the anodic oxidation film uniformly and densely covers the surface of the substrate, the porosity is ≤24%, there is no local looseness, the hardness is about 250-300 HV, and according to GB / T 10125-2021 “Salt Spray Test for Artificial Atmosphere Corrosion Test”, after 500 hours of neutral salt spray test, the surface of the film layer has no corrosion signs.

[0077] Example 1

[0078] (1) Clamping: using the special tool for anodic oxidation as shown in Figure 1 , the inner wall of the titanium alloy cylindrical part is clamped outside the chuck, and is fixed firmly.

[0079] (2) Chemical degreasing: the clamped tool and the titanium alloy cylindrical part are placed in a chemical degreasing solution, and the degreasing time is set to 10 min.

[0080] (3) First water washing: after chemical degreasing, the clamped tool and the titanium alloy cylindrical part are washed with water.

[0081] (4) Activation: the clamped tool and the titanium alloy cylindrical part are placed in an activation solution, and are taken out immediately after 8 s.

[0082] (5) Second water washing: after activation, the clamped tool and the titanium alloy cylindrical part are washed with water.

[0083] (6) Anodic oxidation: the clamped tool and the titanium alloy cylindrical part are placed in an anodic oxidation solution.

[0084] The anodic oxidation process conditions are as follows:

[0085] First stage: voltage: 18 V, temperature: 20℃, time: 0.5 min, cathode is a lead plate, the titanium alloy cylindrical part is connected to the positive pole of the power supply, and the lead plate is connected to the negative pole of the power supply; the chuck and the titanium alloy cylindrical part are driven to rotate by the driving gear, and the rotating speed is 0.02 m / s.

[0086] Second stage: voltage: 22 V, temperature: 20℃, time: 10 min, cathode is a lead plate, the titanium alloy cylindrical part is connected to the positive pole of the power supply, and the lead plate is connected to the negative pole of the power supply; the chuck and the titanium alloy cylindrical part are driven to rotate by the driving gear, and the rotating speed is 0.05 m / s.

[0087] (7) Water washing: after anodic oxidation, the clamped tool and the titanium alloy cylindrical part are washed with water.

[0088] (8) Removing the part: after water washing, the titanium alloy cylindrical part is removed from the tool.

[0089] (9) Blow drying: the titanium alloy cylindrical part is blown dry in time using clean compressed air.

[0090] The anodic oxidation film uniformly and densely covers the surface of the base body, the porosity is about 23.8%, there is no local looseness, the hardness is about 250-270 HV, and according to GB / T 10125-2021 "Salt Spray Test for Artificial Atmosphere Corrosion Test", after 500 hours of neutral salt spray test, there is no corrosion on the surface of the film layer.

[0091] Example 2

[0092] The anodic oxidation process conditions are different from those of Example 1, and other parameters are the same.

[0093] First stage: voltage: 15V, temperature: 10℃, time: 3min, cathode is lead plate, titanium alloy cylindrical part is connected with positive pole of power supply, lead plate is connected with negative pole of power supply; driving gear drives chuck and titanium alloy cylindrical part to rotate, rotating speed is 0.02m / s;

[0094] Second stage: voltage: 22V, temperature: 10℃, time: 15min, cathode is lead plate, titanium alloy cylindrical part is connected with positive pole of power supply, lead plate is connected with negative pole of power supply; driving gear drives chuck and titanium alloy cylindrical part to rotate, rotating speed is 0.05m / s.

[0095] The anodic oxidation film uniformly and densely covers the surface of the base body, the porosity is about 23.1%, there is no local looseness, the hardness is about 275-295 HV, and according to GB / T 10125-2021 "Salt Spray Test for Artificial Atmosphere Corrosion Test", after 500 hours of neutral salt spray test, there is no corrosion on the surface of the film layer.

[0096] Example 3

[0097] The anodic oxidation process conditions are different from those of Example 1, and other parameters are the same.

[0098] First stage: voltage: 18V, temperature: 30℃, time: 5min, cathode is lead plate, titanium alloy cylindrical part is connected with positive pole of power supply, lead plate is connected with negative pole of power supply; driving gear drives chuck and titanium alloy cylindrical part to rotate, rotating speed is 0.01m / s;

[0099] Second stage: voltage: 22V, temperature: 30℃, time: 10min, cathode is lead plate, titanium alloy cylindrical part is connected with positive pole of power supply, lead plate is connected with negative pole of power supply; driving gear drives chuck and titanium alloy cylindrical part to rotate, rotating speed is 0.04m / s.

[0100] The anodic oxidation film uniformly and densely covers the surface of the base body, the porosity is about 22.8%, there is no local looseness, the hardness is about 280-300 HV, and according to GB / T 10125-2021 "Salt Spray Test for Artificial Atmosphere Corrosion Test", after 500 hours of neutral salt spray test, there is no corrosion on the surface of the film layer.

[0101] In this embodiment, because the first-stage voltage is relatively high, the oxidation time is relatively long, and the rotation speed is relatively slow, the oxidation film is fully grown in the initial stage of formation, so the hardness of the oxidation film is high, the porosity is low, and the quality of the anodic oxidation film is relatively good.

[0102] Comparative Example 1

[0103] The anodic oxidation process conditions are different from those in Example 1, and other parameters are the same.

[0104] First stage: voltage: 18V, temperature: 20℃, time: 3min, cathode is lead plate, titanium alloy cylindrical part is connected to positive pole of power supply, lead plate is connected to negative pole of power supply, and the part is in a static state during the anodic oxidation process.

[0105] Second stage: voltage: 22V, temperature: 20℃, time: 10min, cathode is lead plate, titanium alloy cylindrical part is connected to positive pole of power supply, lead plate is connected to negative pole of power supply, and the part is in a static state during the anodic oxidation process.

[0106] The anodic oxidation film uniformly and densely covers the surface of the base body, the porosity is about 22.8%, there is no local looseness, the hardness is about 280-300 HV, and according to GB / T 10125-2021 "Salt Spray Test for Artificial Atmosphere Corrosion Test", after 500 hours of neutral salt spray test, there is no corrosion on the surface of the film layer.

[0107] Comparative Example 2

[0108] The anodic oxidation process conditions are different from those in Example 1, and other parameters are the same.

[0109] First stage: voltage: 18V, temperature: 30℃, time: 5min, cathode is lead plate, titanium alloy cylindrical part is connected to positive pole of power supply, lead plate is connected to negative pole of power supply; driving gear drives chuck and titanium alloy cylindrical part to rotate at a speed of 0.1m / s;

[0110] Second stage: voltage: 22V, temperature: 30℃, time: 10min, cathode is lead plate, titanium alloy cylindrical part is connected to positive pole of power supply, lead plate is connected to negative pole of power supply; driving gear drives chuck and titanium alloy cylindrical part to rotate at a speed of 0.1m / s.

[0111] The anodic oxidation film is basically uniformly covered on the surface of the base, the porosity is 28.7%, and too fast rotating speed can cause the directional disorder of the film layer growth, the film layer has local loose or pinhole phenomenon, the hardness is 220-240 HV (slightly higher than that of the comparative example 1 in a static state), and after 500 hours of neutral salt spray test, the film layer surface has slight corrosion marks.

[0112] Comparative example 3

[0113] The anodic oxidation process condition is different from that of the example 1, and other parameters are the same.

[0114] The first stage: voltage: 10 V, temperature: 20 DEG C, time: 5 min, the cathode is a lead plate, the titanium alloy cylindrical part is connected with the positive pole of the power supply, the lead plate is connected with the negative pole of the power supply; the driving gear drives the chuck and the titanium alloy cylindrical part to rotate, and the rotating speed is 0.01 m / s.

[0115] The second stage: voltage: 15 V, temperature: 20 DEG C, time: 10 min, the cathode is a lead plate, the titanium alloy cylindrical part is connected with the positive pole of the power supply, the lead plate is connected with the negative pole of the power supply; the driving gear drives the chuck and the titanium alloy cylindrical part to rotate, and the rotating speed is 0.04 m / s.

[0116] The anodic oxidation film is basically uniformly covered on the surface of the base, the porosity is 26.5% (since the rotating speed is appropriate and the gradient voltage is adopted, the technical effect of reducing the porosity is achieved to a certain extent, but the oxidation film growth is insufficient), but too low voltage can cause the film layer to be thin, poor corrosion resistance and hardness, the hardness is 180-200 HV, and after 500 hours of neutral salt spray test, the color of the film layer surface changes greatly, and serious corrosion marks appear.

[0117] In the static oxidation state, the anodic oxidation process can generate a large amount of heat and is not easy to conduct, and at the same time, the static state is not easy to 'wash away' the micro loose on the surface of the film layer, which can cause the hardness and appearance of the film layer to be poor. Too low oxidation voltage can weaken the penetration ability of the cations, causing the film layer to be too thin, poor hardness and corrosion resistance.

[0118] In summary, the anodic oxidation film prepared by the anodization method provided by the application has high hardness (250-300 HV), high density and porosity ≤24%, and almost no local loose / peeling defects occur.

[0119] The titanium alloy cylindrical part treated by the anodization method provided by the application has significantly improved wear resistance and corrosion resistance, according to GB / T 10125-2021 'Salt Spray Test for Artificial Atmosphere Corrosion Test', after 500 hours of neutral salt spray test, the film layer surface has no corrosion marks.

[0120] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for anodizing titanium alloy cylindrical parts, characterized in that: During the anodizing process, the titanium alloy cylindrical part continuously rotates unidirectionally along the axis in the anodizing solution, and the rotation linear speed and voltage increase in steps.

2. The anodizing method according to claim 1, wherein: The anodizing method specifically comprises the following steps: S1 assembly: clamp the titanium alloy cylindrical parts onto the special tooling for anodizing; S2 Degreasing: Place the clamped fixture and the titanium alloy cylindrical part together in a chemical degreasing solution for degreasing. S3 water washing and activation: the degreased tooling and the titanium alloy cylindrical parts are washed with water once, then placed in the activation solution for activation and then washed with water twice; S4 anodizing: The tooling after secondary water washing is placed together with the titanium alloy cylindrical part in anodizing solution for anodizing. During the anodizing process, the titanium alloy cylindrical part is continuously rotated along the axis in the anodizing solution, and the rotation linear speed and voltage are increased in a step-by-step manner; S5 post-processing: After anodizing, the tooling and the titanium alloy cylindrical part are taken out and washed with water. After washing, the titanium alloy cylindrical part is removed and blown dry.

3. The anodizing method according to claim 2, wherein: The step-by-step increase in step S4 includes two stages; In the first stage, the titanium alloy cylindrical part rotates at a linear speed of 0.01 to 0.02 m / s, a temperature of 10 to 30°C, a voltage of 15 to 18 V, and a duration T1 of 0.5 to 5 min. In the second stage, the titanium alloy cylindrical part rotates at a linear speed of 0.03 to 0.05 m / s, a temperature of 10 to 30° C., a voltage of 20 to 22 V, and a duration T2 of 10 to 15 minutes.

4. The anodizing method according to claim 2, wherein: The special anodizing tooling includes a support frame and a rotating assembly; The rotating assembly is rotatably connected to the supporting frame; The rotating assembly includes a driving gear, a transmission shaft and a chuck. The driving gear is installed at one end of the transmission shaft, and the chuck is installed at the other end of the transmission shaft. The three are coaxially installed and can rotate synchronously; the chuck is used to clamp the titanium alloy cylindrical part.

5. The anodizing method according to claim 4, wherein: The chuck is detachably connected to the transmission shaft, and chucks of different sizes are selected according to the specifications of the titanium alloy cylindrical piece.

6. The anodizing method according to claim 2, wherein: The specific composition of the chemical degreasing solution in step S2 is: Na3PO4 40-60g / L, NaOH 40-60g / L, Na2CO3 20-40g / L, Na2SO3 5-12g / L; the degreasing temperature is 40-70°C, and the time is 5-30 minutes.

7. The anodizing method according to claim 2, wherein: The specific composition of the activation solution in step S3 is: HF 30-50 g / L, HNO 3 80-100 g / L.

8. The anodizing method according to claim 2, wherein: The activation conditions in step S3 are: activation temperature is room temperature, and activation time is 5 to 10 seconds.

9. A special tool for anodizing, characterized in that: The special tooling is used to implement the anodizing method according to any one of claims 1 to 8; The special tooling includes a support frame and a rotating assembly; The rotating assembly is rotatably connected to the supporting frame; The rotating assembly includes a driving gear, a transmission shaft and a chuck. The driving gear is installed at one end of the transmission shaft, and the chuck is installed at the other end of the transmission shaft. The three are coaxially installed and can rotate synchronously; the chuck is used to clamp the titanium alloy cylindrical part.

10. A titanium alloy cylindrical part, characterized in that: The titanium alloy cylindrical member has an oxide film formed by the anodizing method according to any one of claims 1 to 8.

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