Titanium alloy mirror polishing process

Abstract

The invention relates to the field of titanium alloy polishing, and discloses a titanium alloy mirror polishing process which comprises the following steps: S1, a pretreatment stage: removing an oxide layer and pollutants on the surface of a titanium alloy workpiece through electrolytic passivation and ultrasonic cleaning; s2, the rough polishing stage is conducted, specifically, the titanium alloy workpiece is polished through a polishing disc, and a pulse gas-liquid two-phase cooling system is used for cooling; and S3, a fine polishing stage: finishing the surface of the titanium alloy workpiece to submicron roughness by using a polishing solution and a polishing pad, and meanwhile, adopting a gradient cooling strategy. According to the method, three-stage cooling is arranged, pulse gas-liquid two-phase cooling is adopted in the rough polishing stage, infrared real-time temperature measurement is matched, beta-phase crystal grain coarsening is restrained, hydrogen peroxide reaction heat release is effectively controlled in a gradient cooling strategy in the fine polishing stage, thickening of a local oxide layer is avoided, and molecular-level polishing without thermal stress residues is achieved through final polishing constant-temperature control.

Description

Technical Field

[0001] The invention relates to the field of titanium alloy polishing, in particular to a titanium alloy mirror polishing process. Background Art

[0002] In modern industrial manufacturing, titanium alloys are widely used in a wide range of high-end industries, including aerospace, medical devices, and precision electronics, due to their exceptional properties, including high strength, low density, excellent corrosion resistance, and biocompatibility. These applications often place extremely high demands on the surface quality of titanium alloys, making mirror polishing a key step in improving their performance and appearance. Currently, the mainstream titanium alloy polishing process utilizes a cloth wheel combined with polishing wax.

[0003] After searching, the publication number is CN110586872A: a dry polishing process is adopted, relying on a high-speed cloth wheel to remove materials, but the problem of surface oxidation caused by temperature rise is not solved; the publication number is JP2020128123A: a water-based coolant is introduced, but a single nozzle cooling is used, resulting in uneven cooling, and local pitting defects still exist; the publication number is US20210001345A1: a chemical mechanical polishing (CMP) liquid formula is proposed, but it has poor adaptability to titanium alloys and low polishing efficiency.

[0004] First, the lack of an effective cooling mechanism during the polishing process causes local temperatures to rise sharply, often exceeding 300°C. Under such high temperatures, the β-phase grains on the titanium alloy's surface rapidly coarsen, while the oxide layer significantly thickens. This coarsening of the β-phase grains directly weakens the titanium alloy's mechanical properties and reduces its structural stability. The thickening of the oxide layer not only affects the material's corrosion resistance but can also alter its surface physical and chemical properties, adversely affecting subsequent processing and application.

[0005] In terms of surface quality, traditional processes can only achieve a surface roughness (Ra) of 0.1μm, far from meeting the stringent optical mirror-grade requirements (Ra ≤ 0.02μm) for components such as optical instruments and high-end medical devices. Furthermore, due to high temperatures and the uneven distribution of shear forces caused by the soft contact between the polishing wheel and the wax, titanium alloy surfaces are susceptible to blistering and swelling, as well as numerous pitting and cavities. These surface defects severely impact the aesthetic appearance and performance of titanium alloy products. Summary of the Invention

[0006] In order to solve the above-mentioned problems, the present invention is implemented through the following technical solutions.

[0007] A titanium alloy mirror polishing process comprises the following steps: S1: Pretreatment stage: remove the oxide layer and contaminants on the surface of titanium alloy workpiece through electrolytic passivation and ultrasonic cleaning; S2: Rough polishing stage: The titanium alloy workpiece is polished using a polishing disc and cooled using a pulsed gas-liquid two-phase cooling system; S3: Fine polishing stage: Use polishing liquid and polishing pad to trim the surface of titanium alloy workpiece to submicron roughness, while adopting gradient cooling strategy; S4: Final polishing stage: Ultra-fine polishing is completed through nano-diamond suspension and constant temperature control to give the titanium alloy workpiece a mirror effect.

[0008] Preferably, in S1, electrolytic passivation is to place the titanium alloy workpiece in an electrolyte, apply a passivation voltage to remove the native oxide layer on the surface of the titanium alloy, and form a passivation film on the surface of the titanium alloy after passivation; ultrasonic cleaning is to place the workpiece in a mixed liquid for ultrasonic cleaning to remove micron-sized particle contaminants, and then dry it by nitrogen purging after cleaning.

[0009] Preferably, the electrolyte comprises 10% nitric acid, 2% hydrofluoric acid and deionized water, the applied voltage is 4-6V, the passivation voltage treatment time is 2-5 minutes, the electrolyte temperature is controlled at 20-30°C, and the thickness of the generated passivation film is less than 50nm; the mixed solution is composed of a non-ionic surfactant and deionized water, the ultrasonic frequency is 30-50kHz, the power is 150-250W, the cleaning time is 8-12 minutes, the nitrogen pressure is 0.2-0.4MPa, and the drying time is 1-3 minutes.

[0010] Preferably, in S2, the polishing disc is made of carbon fiber reinforced ceramics, and the surface of the polishing disc is inlaid with diamond powder; the pulsed gas-liquid two-phase cooling system includes compressed air and coolant mixed in a certain proportion.

[0011] Preferably, the particle size of the diamond powder is 15-25 μm, the concentration is 25% to 35%, and the distribution density of the diamond powder is 150-250 particles / cm 2 , fixed to the surface of the polishing disk by laser cladding; the mixing ratio of compressed air to coolant is 2:1-4:1, the pulse frequency is 4-6Hz, the single injection time is 0.08-0.12s, the interval time is 0.15-0.25s, and the coolant contains 3-7wt% boron nitride nanosheets dispersed in a water-based medium.

[0012] Preferably, in S2, the polishing disc speed is 2000-3000 rpm, and the pressure is 15-25 N / cm 2 , the temperature of the polishing area is monitored in real time by an infrared thermal imager and the temperature rise is controlled to be less than 80°C, so that the surface roughness of the titanium alloy is reduced to 0.3-0.7μm.

[0013] Preferably, in S3, the polishing liquid comprises the following components: nano-silicon dioxide (5-15wt%, particle size 30-70nm); hydrogen peroxide (3-7wt%); ionic liquid (20-40wt% [EMIM] TFSI); pH buffer; anionic surfactant (0.05-0.3wt%).

[0014] Preferably, the gradient cooling strategy includes: the cooling liquid flow rate in the polishing center area is 2.0-4.0 L / min; the cooling liquid flow rate in the edge area is 0.5-1.5 L / min; the temperature in the polishing center area is less than 50°C, and the temperature in the edge area is less than 60°C.

[0015] Preferably, the polishing pad consists of a surface layer, a middle layer and a bottom layer, the surface layer is porous polyurethane, the middle layer is a silicon carbide fiber mesh, and the bottom layer is a silicone buffer layer.

[0016] Preferably, in S4, the nanodiamond suspension comprises 3-8 wt% nanodiamond particles dispersed in a polyethylene glycol carrier; 0.05-0.2 wt% dispersant is added, and ultrasonic dispersion is used to ensure stability, the polishing zone temperature is controlled at 25-35 ° C, a circulating water cooling system is used, the coolant flow rate is 1.5-2.5 L / min, the polishing disc speed is 200-400 rpm, and the pressure is 1-3 N / cm 2 , time 20-40 minutes, so that the surface roughness of the titanium alloy is less than 0.02μm.

[0017] The present invention provides a titanium alloy mirror polishing process. Compared with existing technologies, this process has the following advantages: a three-stage cooling system is implemented. Pulsed gas-liquid two-phase cooling is used in the rough polishing stage, combined with infrared real-time temperature measurement to suppress β-phase grain coarsening. A gradient cooling strategy is used in the fine polishing stage to effectively control the exothermicity of the hydrogen peroxide reaction, preventing localized oxide layer thickening. Constant temperature control is used in the final polishing to achieve molecular-level polishing without residual thermal stress. Through coordinated polishing and nanofluid lubrication polishing, the surface roughness is gradually reduced from pretreatment, rough polishing, fine polishing, to final polishing, ultimately reducing the surface roughness from 0.1μm to 0.01μm or even lower, reaching optical mirror quality. This eliminates surface defects such as blistering, swelling, pitting, and cavities caused by high temperature and uneven shear force, thereby improving the aesthetic appearance and performance of titanium alloy products. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Flowchart of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described below with reference to specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of protection of the present invention.

[0020] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0021] Example 1 Reference Figure 1 , a titanium alloy mirror polishing process, comprising the following steps: S1: Pretreatment stage: remove the oxide layer and contaminants on the surface of titanium alloy workpiece through electrolytic passivation and ultrasonic cleaning; S2: Rough polishing stage: The titanium alloy workpiece is polished using a polishing disc and cooled using a pulsed gas-liquid two-phase cooling system; S3: Fine polishing stage: Use polishing liquid and polishing pad to trim the surface of titanium alloy workpiece to submicron roughness, while adopting gradient cooling strategy; S4: Final polishing stage: Ultra-fine polishing is completed through nano-diamond suspension and constant temperature control to give the titanium alloy workpiece a mirror effect.

[0022] In S1, electrolytic passivation is to place the titanium alloy workpiece in an electrolyte and apply a passivation voltage to remove the native oxide layer on the surface of the titanium alloy, and to form a passivation film on the surface of the titanium alloy after passivation; ultrasonic cleaning is to place the workpiece in a mixed liquid for ultrasonic cleaning to remove micron-sized particle contaminants, and then dry it by nitrogen purging after cleaning.

[0023] The electrolyte includes 10% nitric acid, 2% hydrofluoric acid and deionized water, the applied voltage is 4V, the passivation voltage treatment time is 2 minutes, the electrolyte temperature is controlled at 20°C, and the thickness of the generated passivation film is less than 50nm; the mixed liquid is composed of a non-ionic surfactant and deionized water, the ultrasonic frequency is 30kHz, the power is 150W, the cleaning time is 8 minutes, the nitrogen pressure is 0.2MPa, and the drying time is 1 minute.

[0024] In S2, the polishing disc is made of carbon fiber reinforced ceramics, and the surface of the polishing disc is inlaid with diamond powder; the pulse gas-liquid two-phase cooling system includes compressed air and coolant mixed in a certain proportion.

[0025] The particle size of the diamond powder is 15 μm, the concentration is 25%, and the distribution density of the diamond powder is 150 particles / cm 2 , fixed to the surface of the polishing disk by laser cladding; the mixing ratio of compressed air to coolant is 2:1, the pulse frequency is 4 Hz, the single injection time is 0.08 s, the interval time is 0.15 s, and the coolant contains 3 wt% boron nitride nanosheets dispersed in a water-based medium.

[0026] In S2, the polishing disc speed is 2000 rpm and the pressure is 15 N / cm 2 , the temperature of the polishing area is monitored in real time by an infrared thermal imager and the temperature rise is controlled to be less than 80°C, so that the surface roughness of the titanium alloy is reduced to 0.3μm.

[0027] In the S3, the polishing liquid contains the following components: nano-silicon dioxide (5 wt %, particle size 300 nm); hydrogen peroxide (3 wt %); ionic liquid (20 t % [EMIM] TFSI); pH buffer; anionic surfactant (0.05 wt %).

[0028] The gradient cooling strategy includes: the cooling liquid flow rate in the polishing center area is 2.0 L / min; the cooling liquid flow rate in the edge area is 0.5 L / min; the temperature in the polishing center area is less than 50°C, and the temperature in the edge area is less than 60°C.

[0029] The polishing pad consists of a surface layer, a middle layer and a bottom layer. The surface layer is porous polyurethane, the middle layer is a silicon carbide fiber mesh, and the bottom layer is a silica gel buffer layer.

[0030] In S4, the nanodiamond suspension contains 3 wt% nanodiamond particles dispersed in a polyethylene glycol carrier; 0.05 wt% dispersant is added, and stability is ensured by ultrasonic dispersion. The polishing zone temperature is controlled at 25°C, a circulating water cooling system is used, the coolant flow rate is 1.5 L / min, the polishing disc speed is 200 rpm, and the pressure is 1 N / cm 2 , time 20 minutes, the surface roughness of the titanium alloy is less than 0.02μm and the glossiness reaches 98GU (ISO2813).

[0031] Example 2 The difference between this embodiment and the first embodiment is that: S1: Preprocessing stage: Electrolytic passivation: voltage 6 V, treatment time 5 minutes, electrolyte temperature 30 ° C.

[0032] Ultrasonic cleaning: ultrasonic frequency 50 kHz, power 250 W, cleaning time 12 minutes, nitrogen pressure 0.4 MPa, drying time 3 minutes.

[0033] S2: Rough polishing stage: Diamond powder particle size 25μm, concentration 35%, distribution density 250 particles / cm 2 .

[0034] The mixing ratio of compressed air to coolant is 4:1, the pulse frequency is 6 Hz, the single injection time is 0.12 s, the interval time is 0.25 s, and the content of boron nitride nanosheets in the coolant is 7 wt%.

[0035] Polishing disc speed 3000rpm, pressure 25N / cm 2 , the surface roughness is reduced to 0.7μm.

[0036] S3: Fine polishing stage: Polishing liquid composition: 15wt% nano-silica with a particle size of 70nm, 7wt% hydrogen peroxide, 40wt% [EMIM]TFSI ionic liquid, pH buffer and 0.3wt% anionic surfactant.

[0037] The coolant flow rate in the polishing center area is 4.0L / min, and in the edge area is 1.5L / min.

[0038] S4: Final throw stage: The nano-diamond suspension contains 8 wt% of nano-diamond particles and 0.2 wt% of dispersant.

[0039] Coolant flow rate 2.5L / min, polishing zone temperature 35°C, polishing disc speed 400rpm, pressure 3N / cm 2 , polishing time 40 minutes. The final titanium alloy surface roughness is less than 0.02μm, and the glossiness reaches 99GU (ISO2813).

[0040] Example 3 The difference between this embodiment and the first embodiment is that: S1: Preprocessing stage: Electrolytic passivation: voltage 5 V, treatment time 4 minutes, electrolyte temperature 25 °C.

[0041] Ultrasonic cleaning: ultrasonic frequency 40 kHz, power 200 W, cleaning time 10 minutes, nitrogen pressure 0.3 MPa, drying time 2 minutes.

[0042] S2: Rough polishing stage: Diamond powder particle size 20μm, concentration 30%, distribution density 200 particles / cm 2 .

[0043] The mixing ratio of compressed air to coolant is 3:1, the pulse frequency is 5 Hz, the single injection time is 0.1 s, the interval time is 0.2 s, and the content of boron nitride nanosheets in the coolant is 4 wt%.

[0044] Polishing disc speed 2500rpm, pressure 20N / cm 2 , the surface roughness is reduced to 0.5μm.

[0045] S3: Fine polishing stage: Polishing liquid composition: 10wt% nano-silica with a particle size of 50nm, 5wt% hydrogen peroxide, 30wt% [EMIM]TFSI ionic liquid, pH buffer and 0.15wt% anionic surfactant.

[0046] The coolant flow rate in the polishing center area is 3.0L / min, and in the edge area it is 1.0L / min.

[0047] S4: Final throw stage: The nano-diamond suspension contains 5 wt% of nano-diamond particles and 0.1 wt% of dispersant.

[0048] Coolant flow rate 2.0L / min, polishing zone temperature 30°C, polishing disc speed 300rpm, pressure 2N / cm 2 , polishing time 30 minutes. The final titanium alloy surface roughness is less than 0.02μm, and the glossiness reaches 98.5GU (ISO2813).

[0049] Comparison of data from the above examples:

[0050] Pretreatment: Electrolytic passivation parameters (voltage 4-6V, time 2-5 minutes) effectively remove the oxide layer and form a uniform passivation film (<50nm), meeting the requirements for titanium alloy surface pretreatment. Example 3 (5V, 4 minutes) strikes a balance between efficiency and passivation effectiveness.

[0051] During the rough polishing stage, a gradient design of diamond powder particle size (15-25μm) and concentration (25%-35%) was used to meet varying initial roughness requirements. The synergistic effect of high rotational speed (2000-3000rpm) and coolant BNNS concentration (3-7wt%) ensured a temperature rise below 80°C, preventing thermal damage.

[0052] Fine Polishing: Adjusting the ratio of nano-SiO2 (5-15wt%) to H2O2 (3-7wt%) achieves a synergistic effect between chemical oxidation softening and mechanical polishing. A gradient cooling strategy (2.0-4.0L / min in the center zone) effectively suppresses H2O2 decomposition and exotherm, preventing localized temperature increases.

[0053] Final polishing stage: Matching the nanodiamond concentration (3-8wt%) with the polishing temperature (25-35°C) ensures molecular-level material removal (Ra≤0.02μm).

[0054] Titanium alloy mirror polishing process workflow 1. Preprocessing stage Electrolytic passivation: Completely immerse the titanium alloy workpiece in an electrolyte consisting of 10% nitric acid, 2% hydrofluoric acid, and deionized water. Connect the power supply, set the voltage to 5V, and initiate the electrolytic passivation process for 3 minutes. During the electrolysis process, closely monitor the electrolyte temperature and maintain it within the range of 20-30°C using an external cooling device. After the electrolysis is complete, remove the workpiece. The native oxide layer has been removed, and a uniform passivation film less than 50nm thick has formed on the workpiece surface.

[0055] Ultrasonic Cleaning: Prepare a cleaning tank, add deionized water and 0.1% nonionic surfactant, and stir thoroughly. Place the electrolytically passivated workpiece into the cleaning tank, ensuring it is completely covered by the cleaning solution. Start the ultrasonic cleaning equipment, set the frequency to 40kHz, and begin the cleaning process for 10 minutes. During the cleaning process, ultrasonic vibrations create tiny bubbles in the cleaning solution, which burst on the workpiece surface, removing micron-sized particle contaminants. After cleaning, remove the workpiece from the cleaning tank and purge and dry it with nitrogen at a pressure of 0.2-0.4MPa to ensure no residual moisture remains on the surface.

[0056] 2. Rough polishing stage Prepare polishing equipment and tools: Install a carbon fiber-reinforced ceramic polishing pad, ensuring a secure connection and good concentricity between the pad and the polishing equipment. Evenly inlay diamond powder onto the polishing pad surface, securing the powder through laser cladding or other methods to prevent it from falling off during the polishing process.

[0057] Configure the cooling system: Prepare the coolant and evenly disperse the boron nitride nanosheets in a water-based medium to create a coolant with excellent thermal conductivity. Connect a pulsed gas-liquid two-phase cooling system to ensure stable and uniform cooling of the polishing area.

[0058] Rough polishing: Mount the pretreated titanium alloy workpiece on the polishing machine's worktable and adjust the workpiece's position to ensure good contact with the polishing disc surface. Start the polishing machine, activate the cooling system, and monitor the polishing zone temperature in real time using an infrared thermal imager to ensure it remains below 80°C. During the polishing process, the interaction between the diamond powder and the workpiece surface gradually reduces the titanium alloy's surface roughness from an initial 1.5μm to approximately 0.5μm.

[0059] 3. Fine polishing stage Prepare the polishing slurry and polishing pad: Prepare a composite polishing slurry according to the recipe, mixing nano-silica, hydrogen peroxide, ionic liquid, and appropriate amounts of pH buffer and anionic surfactant. Install the polishing pad, ensuring it is tightly connected to the polishing equipment and remains stable during the polishing process.

[0060] Set a gradient cooling strategy: Connect the cooling system and set the coolant flow rate to 3 L / min in the polishing center and 1 L / min in the edge. Use temperature sensors to monitor the temperatures of the polishing center and edge areas in real time, ensuring the center temperature is below 50°C and the edge temperature is below 60°C.

[0061] Perform fine polishing: Re-install the rough-polished workpiece onto the polishing machine's workbench and adjust its position. Start the polishing machine and activate the polishing slurry supply system to evenly coat the workpiece surface. During the polishing process, nano-silicon dioxide mechanically abrades, hydrogen peroxide chemically oxidizes and softens the surface, and the ionic liquid lubricates and provides corrosion resistance. These three factors work synergistically to further refine the workpiece surface, reducing the surface roughness from 0.5μm to approximately 0.05μm.

[0062] 4. Final throwing stage Prepare the nanodiamond suspension and polishing tool: Prepare the nanodiamond suspension by evenly dispersing the nanodiamond particles in a polyethylene glycol carrier. Add sodium lauryl sulfate as a dispersant and ensure the stability of the suspension through ultrasonic dispersion and other methods. Select a microfiber nonwoven fabric as the polishing tool and install it on the polishing head of the polishing equipment, ensuring it is secure and flat. Connect the circulating water cooling system and use deionized water as the coolant.

[0063] Final polishing: Place the finished workpiece on the polishing machine's workbench and adjust its position. Start the polishing machine and simultaneously activate the nanodiamond suspension supply system, ensuring the suspension is evenly applied to the workpiece surface. During the polishing process, nanodiamond particles remove material at the molecular level, further improving the workpiece's surface quality. Ultimately, the titanium alloy's surface roughness is reduced to less than 0.02 μm, achieving a mirror-like finish.

[0064] In summary, compared with the existing technology, it has the following beneficial effects: By setting up three-stage cooling, pulse gas-liquid two-phase cooling is used in the rough polishing stage, combined with infrared real-time temperature measurement to suppress the coarsening of β-phase grains. The gradient cooling strategy in the fine polishing stage effectively controls the exothermicity of the hydrogen peroxide reaction to avoid local thickening of the oxide layer. The final polishing constant temperature control achieves molecular-level polishing without residual thermal stress.

[0065] Through collaborative polishing and nanofluid lubrication polishing, the surface roughness is gradually reduced from pretreatment, rough polishing, fine polishing to final polishing, and eventually the surface roughness can be reduced from 0.1μm to 0.01μm or even lower, reaching the optical mirror level, eliminating surface defects such as blistering, swelling, pitting and holes caused by high temperature and uneven shear force, and improving the appearance and performance of titanium alloy products.

[0066] The total working hours have also been shortened. Efficient polishing tools and cooling systems are used in the rough polishing stage, and polishing fluid, polishing pads and cooling strategies are reasonably matched in the fine polishing and final polishing stages. The close coordination of each stage has reduced processing time and improved production efficiency.

[0067] Thus, although the invention has been described herein with reference to specific embodiments thereof, freedom of modification, various changes and substitutions are contemplated within the foregoing disclosure, and it should be understood that in some cases, some features of the invention will be employed without the corresponding use of other features without departing from the scope and spirit of the claimed invention. Thus, many modifications may be made to adapt a particular environment or material to the true scope and spirit of the invention. The invention is not intended to be limited to the specific terminology used in the claims below and / or to the specific embodiments disclosed as the best mode contemplated for carrying out the invention, but the invention is intended to include any and all embodiments and equivalents falling within the scope of the appended claims. Thus, the scope of the invention will be determined solely by the appended claims.

Claims

1. A titanium alloy mirror polishing process, characterized in that: The following steps are involved: S1: Pretreatment stage: remove the oxide layer and contaminants on the surface of titanium alloy workpiece through electrolytic passivation and ultrasonic cleaning; S2: Rough polishing stage: The titanium alloy workpiece is polished using a polishing disc and cooled using a pulsed gas-liquid two-phase cooling system; S3: Fine polishing stage: Use polishing liquid and polishing pad to trim the surface of titanium alloy workpiece to submicron roughness, while adopting gradient cooling strategy; S4: Final polishing stage: Ultra-fine polishing is completed through nano-diamond suspension and constant temperature control to give the titanium alloy workpiece a mirror effect.

2. The titanium alloy mirror polishing process according to claim 1, characterized in that: In S1, electrolytic passivation is to place the titanium alloy workpiece in an electrolyte and apply a passivation voltage to remove the native oxide layer on the surface of the titanium alloy and form a passivation film on the surface of the titanium alloy after passivation; Ultrasonic cleaning is to place the workpiece into a mixed liquid for ultrasonic cleaning to remove micron-sized particle contaminants, and then dry it by nitrogen purging after cleaning.

3. The titanium alloy mirror polishing process according to claim 2, characterized in that: The electrolyte comprises 10% nitric acid, 2% hydrofluoric acid and deionized water, the applied voltage is 4-6V, the passivation voltage treatment time is 2-5 minutes, the electrolyte temperature is controlled at 20-30°C, and the thickness of the generated passivation film is less than 50nm; The mixed liquid consists of a nonionic surfactant and deionized water, the ultrasonic frequency is 30-50 kHz, the power is 150-250 W, the cleaning time is 8-12 minutes, the nitrogen pressure is 0.2-0.4 MPa, and the drying time is 1-3 minutes.

4. The titanium alloy mirror polishing process according to claim 1, characterized in that: In S2, the polishing disc is made of carbon fiber reinforced ceramics, and the surface of the polishing disc is inlaid with diamond powder; the pulse gas-liquid two-phase cooling system includes compressed air and coolant mixed in a certain proportion.

5. The titanium alloy mirror polishing process according to claim 4, characterized in that: The particle size of the diamond powder is 15-25 μm, the concentration is 25% to 35%, and the distribution density of the diamond powder is 150-250 particles / cm 2 , fixed on the surface of the polishing disc by laser cladding; The mixing ratio of the compressed air to the coolant is 2:1-4:1, the pulse frequency is 4-6 Hz, the single injection time is 0.08-0.12 s, the interval time is 0.15-0.25 s, and the coolant contains 3-7 wt % boron nitride nanosheets dispersed in a water-based medium.

6. The titanium alloy mirror polishing process according to claim 1, characterized in that: In S2, the polishing disc speed is 2000-3000 rpm and the pressure is 15-25 N / cm 2 , the temperature of the polishing area is monitored in real time by an infrared thermal imager and the temperature rise is controlled to be less than 80°C, so that the surface roughness of the titanium alloy is reduced to 0.3-0.7μm.

7. The titanium alloy mirror polishing process according to claim 1, characterized in that: In S3, the polishing liquid contains the following ingredients: Nano-silicon dioxide (5-15wt%, particle size 30-70nm); Hydrogen peroxide (3-7 wt%); Ionic liquid (20-40 wt% [EMIM]TFSI); pH buffers; Anionic surfactant (0.05-0.3wt%).

8. The titanium alloy mirror polishing process according to claim 1, characterized in that: The gradient cooling strategy includes: The coolant flow rate in the polishing center area is 2.0-4.0L / min; The coolant flow rate in the edge area is 0.5-1.5L / min; The temperature of the polishing center area is less than 50℃, and the temperature of the edge area is less than 60℃.

9. The titanium alloy mirror polishing process according to claim 1, characterized in that: The polishing pad consists of a surface layer, a middle layer and a bottom layer. The surface layer is porous polyurethane, the middle layer is a silicon carbide fiber mesh, and the bottom layer is a silica gel buffer layer.

10. The titanium alloy mirror polishing process according to claim 1, characterized in that: In said S4, the nanodiamond suspension comprises 3-8 wt% nanodiamond particles dispersed in a polyethylene glycol carrier; Add 0.05-0.2wt% dispersant and ensure stability through ultrasonic dispersion. The temperature of the polishing area is controlled at 25-35℃. A circulating water cooling system is used with a coolant flow rate of 1.5-2.5L / min, a polishing disc speed of 200-400rpm, and a pressure of 1-3N / cm 2 , time 20-40 minutes, so that the surface roughness of the titanium alloy is less than 0.02μm.

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