A surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece

Abstract

The application relates to the technical field of titanium alloy surface treatment, in particular to a surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces, which comprises the following steps: after sand blasting treatment of the titanium alloy workpieces, the titanium alloy workpieces are placed as cathodes in an electrochemical mixed solution to remove oil films, and then the titanium alloy workpieces are hydrogenated after water washing; after nickel immersion treatment of the hydrogenated titanium alloy workpieces, the titanium alloy workpieces are pre-plated with nickel as cathodes, the anode material and the electroplating solution are replaced, and the titanium alloy workpieces are plated with chromium; in the electroplating process, the current density of the anode at each sampling time, the conductivity of the anode and the cathode are analyzed, and the electroplating current at each sampling time is adjusted; and after the electroplating is completed, the titanium alloy workpieces are water washed and then the plating layer is stabilized. The application aims to improve the uniformity and corrosion-resistant characteristics of the electroplating plating layer.

Description

Technical Field

[0001] This application relates to the field of titanium alloy surface treatment technology, specifically to a surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces. Background Technology

[0002] Titanium alloys are widely used in many fields of modern industry due to their unique properties. Titanium alloys possess advantages such as low density, high specific strength, and high high-temperature strength, making them widely applicable in aerospace, automotive, medical, and machinery manufacturing industries. However, titanium alloys also have certain shortcomings in practical applications. Due to their relatively low hardness, they are susceptible to adhesive wear and fretting wear. Therefore, specific surface treatment processes are needed to improve the wear resistance and corrosion resistance of titanium alloy workpieces.

[0003] Current processing techniques for titanium alloy workpieces mainly include: mechanical polishing, chemical mechanical polishing, cold treatment, heat treatment, sandblasting, and electroplating. Electroplating, in particular, isolates the titanium alloy substrate from direct contact with the corrosive environment, improving the wear resistance and corrosion resistance of the workpiece. During electroplating, pretreatment of the titanium alloy workpiece enhances the bond between the substrate and the plating layer. In the electroplating process, current density is a key factor affecting the coating. Insufficient current density leads to inadequate deposition, resulting in coarse crystals and poor corrosion resistance. Conversely, excessive current density can cause insufficient ion diffusion, leading to scorching or dendrite growth in the coating.

[0004] Currently, current density control in the electroplating process relies on preset parameters. In the initial stage of electroplating, the current density is low, ensuring uniform metal ion distribution in the coating. In the middle stage, the current density is increased to accelerate the plating process. In the later stage, the current density is reduced to improve coating uniformity. While this method can improve coating uniformity to a certain extent and enhance the wear and corrosion resistance of titanium alloy workpieces, the inconsistent nature of current density changes leads to abrupt changes in grain size during sudden current density fluctuations. This affects the overall integrity of the coating and reduces its protective effect on the titanium alloy workpiece. Summary of the Invention

[0005] In view of the above, it is necessary to provide a surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces to solve the above problems.

[0006] One embodiment of this application provides a surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces, the process comprising:

[0007] After sandblasting, the titanium alloy workpiece is placed in an electrochemical mixture as a cathode to remove the oil film, and then hydrogenated after washing with water.

[0008] After the hydrogenated titanium alloy workpiece is immersed in nickel, it is used as the cathode for pre-nickel plating. Then, the anode material and electroplating solution are changed to chromium plating the titanium alloy workpiece.

[0009] During the electroplating process, the current density at each preset position of the anode at each sampling time is obtained; the conductivity of the anode and cathode is collected.

[0010] Analyze the overall distribution characteristics of current density at all locations of the anode at each sampling time, and determine the difference in current density at each sampling time;

[0011] A time window is preset for each sampling moment. The differences in current density distribution between all pairs of positions within the time window are analyzed. Based on the current density difference value, the electroplating uniformity at each sampling moment is determined.

[0012] Based on the difference in conductivity between the anode and cathode in the electroplating solution at each sampling time, the ion trend difference at each sampling time is obtained;

[0013] Based on the electroplating uniformity and ion trend differences at each sampling time, an adjustment coefficient for the electroplating current at each sampling time is obtained, and the electroplating current at each sampling time is adjusted accordingly.

[0014] After electroplating, the titanium alloy workpiece is washed with water to stabilize the coating.

[0015] The electrochemical mixture is specifically a mixed solution of NaOH, Na2CO3·10H2O, Na3PO4·12H2O, and Na2SiO3; the concentrations of each component in the electrochemical mixture are: NaOH 25~50 g / L, Na2CO3·10H2O 30~60 g / L, Na3PO4·12H2O 20~50 g / L, and Na2SiO3 5~10 g / L; the anode material used in the oil film removal process is a steel plate, the temperature is 70~90℃, and the time is 5~15 min.

[0016] The specific operation of hydrogenation after water washing is as follows: the water-washed titanium alloy workpiece is placed in a mixed hydrogenation solution, which is a mixed solution of HCl and H2SO4, wherein the concentration of H2SO4 is 1~2g / ml, the concentration of HCl is 1~2g / ml, and the volume ratio of H2SO4 to HCl solution is between 2:1 and 3:1. The total volume of the hydrogenation solution is 2L, the temperature of the mixed solution during hydrogenation is 15~25℃, and the hydrogenation time is 60~100min.

[0017] The specific operation of the nickel immersion treatment is as follows: the titanium alloy workpiece is placed in a nickel mixed solution, wherein the concentrations of each component in the nickel mixed solution are: NiCl2·6H2O is 10~25g / L and H3PO4 is 1400~1600g / L; the temperature during nickel immersion is 15~25℃ and the duration is 100~150min.

[0018] The electroplating solution for pre-plating nickel is a mixed solution of NiCl2·6H2O with a concentration of 200~400 g / L and HCl with a concentration of 150~200 g / L. The pre-plating temperature is 15~25℃. The titanium alloy workpiece is used as the cathode, the pure nickel plate is used as the anode, the electroplating time is 2~5 min, and the current density is 4~8 A / dm³. 2 .

[0019] The electroplating solution for chromium plating on titanium alloy workpieces is a mixed solution of CrO3, H2SO4, and Cr2O3, with concentrations of 200-300 g / L for CrO3, 2-5 g / L for H2SO4, and 2-5 g / L for Cr2O3, respectively. The electroplating temperature is 45-65°C, and the current density is 15-35 A / dm³. 2 The anode is made of titanium-platinum rod, and the electroplating time is 30~150 minutes.

[0020] The determination of the current density difference value at each sampling time includes:

[0021] Obtain the standard deviation and kurtosis of the current density at all locations at each sampling time;

[0022] The negative correlation mapping result of the kurtosis at each sampling time is positively fused with the standard deviation to obtain the current density difference value at each sampling time.

[0023] Specifically, determining the current density difference value at each sampling time involves:

[0024] The sequence of current density values ​​at all sampling times within the time window corresponding to the current sampling time at each location is denoted as the current density sequence.

[0025] Obtain the mean value of each current density sequence corresponding to the current sampling time, calculate the range of all the mean values ​​of the elements corresponding to the current sampling time, and record it as the first range value; obtain the similarity coefficient of the current density sequences of all pairs of sensors at the current sampling time; record the range of all similarities obtained at the current sampling time as the second range value; after accumulating the first range value and the second range value, and combining them with the current density difference value, obtain the electroplating uniformity at the current sampling time.

[0026] Specifically, obtaining the ion trend difference at each sampling time involves:

[0027] Sequences of conductivity at all sampling times within the time window of each sampling time are obtained for both the anode and cathode. Sequence decomposition is performed on each conductivity sequence to obtain a trend term. This term is then substituted into the trend intensity formula to obtain the trend intensity of the anode and cathode conductivity at each sampling time. The absolute value of the difference between the two is taken as the ion trend difference at each sampling time.

[0028] The specific process of obtaining the adjustment coefficient of the electroplating current at each sampling time and adjusting the electroplating current at each sampling time is as follows:

[0029] Calculate the absolute value of the difference between the coating thickness at each sampling time and half of the target coating thickness, and sum it with the electroplating uniformity.

[0030] The ratio of the ion trend difference at each sampling time to the obtained sum value is normalized to obtain the current adjustment coefficient at each sampling time.

[0031] The product of the current adjustment coefficient and the preset adjustment step size at each sampling time is added to the preset electroplating current value at each sampling time to obtain the adjusted electroplating current value at each sampling time.

[0032] This application has at least the following beneficial effects:

[0033] This application improves the surface roughness and adhesion of titanium alloys through steps such as sandblasting, oil film removal, hydrogenation, nickel immersion, and pre-nickel plating, laying the foundation for subsequent chromium plating. These processes help ensure a uniform and firm chromium plating layer, improving the wear resistance, high-temperature resistance, and corrosion resistance of titanium alloy workpieces, extending their service life, and enhancing their overall performance. Furthermore, by analyzing the current density distribution characteristics at the anode position at each sampling moment, this application can identify differences in current density, thereby optimizing the electroplating process and ensuring a uniform distribution of the electroplated layer across the entire workpiece surface. Simultaneously, by combining the conductivity difference characteristics and dynamically adjusting the electroplating current, it helps to correct non-uniformity in the electroplating process in real time, improving electroplating quality and workpiece surface performance, enhancing the workpiece's corrosion resistance, wear resistance, and other properties, and extending its service life. The water washing process removes residual electroplating solution and impurities from the surface, reducing contaminants that may affect the plating quality and ensuring a more uniform and smooth plating layer. Subsequent stabilization treatment helps to enhance the density and corrosion resistance of the coating, thereby improving the performance of the titanium alloy workpiece and enhancing its wear resistance, high-temperature resistance, and corrosion resistance, ensuring its long-term stability and reliability in practical applications. Finally, through comparative analysis of the embodiments, the electroplating surface treatment process of this application can effectively improve the uniformity and corrosion resistance of the electroplated coating. Attached Figure Description

[0034] Figure 1 A flowchart of a surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces is provided in this application;

[0035] Figure 2 A schematic diagram illustrating the acquisition of current density parameter information provided in this application. Detailed Implementation

[0036] In the description of the embodiments in this application, the words "exemplary," "or," and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of the words "exemplary," "or," and "for example" is intended to present the relevant concepts in a specific manner.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application's specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0038] It should also be noted that the terms "first" and "second" in this application and its accompanying drawings are used to distinguish similar objects, rather than to describe a specific order or sequence. The methods disclosed in the embodiments of this application or the methods shown in the flowcharts include one or more steps for implementing the method. Without departing from the scope of protection of this application, the execution order of multiple steps can be interchanged, and some steps can also be deleted.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0040] Example 1

[0041] Titanium and titanium alloys are often highly reactive and readily react with oxygen in the air to rapidly form a dense oxide film on the surface. This oxide film has high chemical stability and insulation, which hinders the adhesion of metal ions to the titanium alloy workpiece during electroplating and affects the bonding between the coating and the substrate. Therefore, surface pretreatment of titanium alloy workpieces is required before electroplating.

[0042] Sandblasting: Wet sandblasting is performed using sandblasting equipment. The sandblasting medium used is 54# white corundum. The sandblasting pressure is controlled within the range of 0.3~0.7MPa, the sandblasting angle is maintained between 50° and 85°, and the sandblasting time is controlled to be 30s.

[0043] Electrochemical degreasing: This process removes the oil film from titanium alloy workpieces using an electrochemical mixed solution. Specifically, the sandblasted titanium alloy workpiece is placed in a mixed solution of NaOH, Na₂CO₃·10H₂O, Na₃PO₄·12H₂O, and Na₂SiO₃. The concentrations of each component in this mixed solution are: NaOH 25 g / L, Na₂CO₃·10H₂O 30 g / L, Na₃PO₄·12H₂O 20 g / L, and Na₂SiO₃ 10 g / L. The temperature of the mixed solution is adjusted to 70℃, and the electrochemical degreasing time is set to 15 min. During the electrochemical degreasing process, the titanium alloy workpiece is placed at the cathode, and a steel plate is used as the anode. The voltage is controlled at 25V, and the current density is set to 10 A / dm³. 2 After electrochemical degreasing, the product is washed with pure water for 5 minutes.

[0044] Hydrogenation: The titanium alloy workpiece is hydrogenated after water washing to improve its surface activity. The workpiece is placed in a mixed hydrogenation solution, specifically a mixture of HCl and H₂SO₄. The H₂SO₄ concentration is 1 g / ml, the HCl concentration is 2 g / ml, and the volume ratio of H₂SO₄ to HCl is controlled at 2:1. The total volume of the mixed hydrogenation solution is 2 L. The temperature of the mixed solution during hydrogenation is set at 15°C, and the hydrogenation time is set at 100 min.

[0045] Pre-plating nickel: Chromium plating is used on titanium alloy workpieces to improve their wear resistance and corrosion resistance. However, the bonding force between the titanium alloy and the chromium plating layer is weak, making the chromium plating layer easy to fall off. Therefore, an intermediate layer electroplating is required.

[0046] Therefore, the hydrogenated titanium alloy workpiece is first immersed in nickel. The titanium alloy workpiece is placed in a nickel mixed solution with NiCl2·6H2O of 10 g / L and H3PO4 of 1400 g / L. The temperature of the mixed solution during nickel immersion is 15℃ and the immersion time is 150 min.

[0047] After immersion in nickel, pre-plating with nickel is performed. The electroplating solution for nickel plating is a mixed solution of NiCl2·6H2O with a concentration of 200 g / L and HCl with a concentration of 150 g / L. The temperature of the electroplating solution for pre-plating is set to 15℃. The titanium alloy workpiece is used as the cathode, and the pure nickel plate is used as the anode. The electroplating time is 5 min, and the current density is 4 A / dm³. 2 .

[0048] Hard chrome plating: Chromium has high hardness, therefore, chrome plating on titanium alloys can effectively improve their wear resistance and corrosion resistance. The electroplating solution used for chrome plating is a mixed solution of CrO3, H2SO4, and Cr2O3, with concentrations of 200 g / L for CrO3, 2 g / L for H2SO4, and 2 g / L for Cr2O3. The electroplating temperature is set at 45℃, and the current density is set at 15 A / dm³. 2 The anode is made of titanium-platinum rod material (the titanium alloy rod has a 1-3 μm layer of platinum on its surface), and the cathode is made of titanium alloy workpiece. The electroplating time is 150 min.

[0049] Electroplating hard chrome onto the surface of titanium alloys can improve the overall wear resistance and corrosion resistance of titanium alloy workpieces. During the electroplating process, the current density directly affects the surface of the titanium alloy workpiece and needs to be controlled to form a dense and uniform electroplated layer.

[0050] In traditional electroplating processes, the entire electroplating stage is divided into three phases based on time: initial phase (20%), middle phase (50%), and final phase (30%). A fixed current density is set for each phase based on empirical values, and electroplating is stopped when the electroplating time ends or the target thickness is reached. This can easily lead to inconsistent adhesion and uneven plating thickness on the electroplated workpiece, affecting the wear resistance and corrosion resistance of the electroplated titanium alloy workpiece. Therefore, it is necessary to combine data analysis during the electroplating process to achieve dynamic adjustment of the current density. The specific process is as follows:

[0051] S1: During the electroplating process, obtain the current density at each preset position of the anode at each sampling time; collect the conductivity of the anode and cathode.

[0052] During electroplating, current density affects the grain size and uniformity of the electroplated chromium layer. Therefore, it is necessary to measure the current density parameter in real time during the electroplating process. Specific details are as follows: Figure 2 As shown, N magnetic current sensors are uniformly placed on the surface of the anode titanium platinum rod and connected to a digital processor to measure the current density on the electrode. The measurement principle is based on the reference "Design of Online Monitoring System for Current Density during Barrel Plating". At the same time, a galvanometer is connected to the anode to measure the overall current output.

[0053] Furthermore, during the electroplating process, as the plating layer thickens, the ion concentration distribution in the electroplating solution changes, further affecting the transmission of current density. To further characterize the degree of change in ion concentration, probes of conductivity meters were deployed at the anode titanium platinum rod and the cathode titanium alloy workpiece to measure the conductivity of the electroplating solution around the anode and cathode, thereby reflecting the differences in ion distribution in the electroplating solution.

[0054] All of the above sensors are connected to a digital processing unit to achieve digital-to-analog conversion and signal amplification. In this embodiment, the sampling interval of all data sensors is set to be the same, specifically once every 200ms, and the number of magnetic current sensors is set to 12.

[0055] This enables real-time acquisition of electroplating parameters during the chromium electroplating process on titanium alloys.

[0056] S2: Analyze the overall distribution characteristics of the current density at all locations of the anode at each sampling time, and determine the current density difference value at each sampling time.

[0057] In the electroplating process, current density is a key factor affecting plating quality. High current density facilitates rapid reduction of metal ions and a rapid increase in plating thickness, but it can easily lead to coarse grains in the plating crystals and scorching pits on the plating surface. On the other hand, low current density results in finer, smoother, denser plating crystals with lower porosity, but it also reduces plating efficiency and impacts production productivity.

[0058] In the electroplating process of titanium alloy workpieces, the electroplating power supply, anode and cathode and electroplating solution form a closed loop. Since the titanium alloy workpiece at the cathode needs to be electroplated, a sensor is placed on the titanium platinum rod at the anode to collect the current density at various positions on the anode, thereby estimating the current density distribution of the titanium alloy workpiece.

[0059] For a single sampling moment, there are N magnetic current sensors. By analyzing the changes in the magnetic signal, the current density at the position of the anode rod can be determined. Ideally, the current density at each position of the anode rod should be consistent. Its value is affected by the acquisition noise and fluctuates within a small range, showing a normal distribution with a small overall deviation.

[0060] Based on the changes in current density values ​​collected by each magnetic current sensor at the current sampling time, obtain the current density difference value at the current sampling time. Its formula is as follows: In the formula, A represents the difference in current density during the electroplating process of the titanium alloy workpiece at the current sampling time. H represents the standard deviation and kurtosis of the current density collected by N sensors at the current sampling time, and exp() represents an exponential function with the natural constant e as the base. This represents the kurtosis adjustment parameter, set to 3, since the kurtosis of the standard normal distribution is 3.

[0061] For the analysis of current density distribution differences at the current sampling time, under normal circumstances, environmental noise often exhibits a normal distribution. Therefore, during actual data acquisition, current density fluctuations are small, the standard deviation is small, and the kurtosis distribution differs little from the standard normal distribution, resulting in a small difference in current density. Conversely, if the current density difference is large at the current sampling time, it indicates a mismatch between the current value in the electroplating process and the actual electroplating process, suggesting a higher likelihood of needing adjustment.

[0062] The current density difference value is analyzed based on the current density data collected by the sensor at a single sampling moment. It aims to reflect the changes in current density of the titanium alloy workpiece during electroplating, focusing on the distribution characteristics of the current density at that moment to evaluate the electroplating effect. However, this method does not consider the influence of the shape of the titanium alloy workpiece on the current density distribution, and therefore may differ somewhat from the actual electroplating process.

[0063] S2: Preset a time window for each sampling moment, analyze the difference characteristics between the current density distributions at all pairs of positions within the time window, and determine the electroplating uniformity at each sampling moment by combining the current density difference values.

[0064] In the wear-resistant and corrosion-resistant processing of titanium alloy workpieces, they must be finished products, and therefore have certain shape and structural characteristics. These structural characteristics can easily affect the magnitude of current density. Therefore, it is necessary to combine the spatial distribution of electromagnetic sensors on the anode rod to evaluate the uniformity of electroplating.

[0065] During the electroplating process, for the current sampling moment, W sampling moments backward are selected as the evaluation time window. According to experimental analysis, the value of W should preferably be in the range of 50~80. In this embodiment, W is 50. The sequence of current density values ​​of all sampling moments in the time window corresponding to the current sampling moment of each electromagnetic sensor during the electroplating process is recorded as the current density sequence.

[0066] During the electroplating process, because the anode titanium platinum rod is a uniform rod while the titanium alloy workpiece has certain shape and structural characteristics, the closer the anode rod is to the convex part of the titanium alloy workpiece, the smaller the corresponding internal resistance. Consequently, the current density at this convex part is higher and fluctuates significantly as the current density increases. For other parts of the titanium alloy workpiece, the current density at the corresponding anode rod position is lower, and the fluctuation in current density is smaller with changes in the overall electroplating current.

[0067] Based on this, the electroplating uniformity at the current sampling time is obtained. Specifically: the mean value of each current density sequence corresponding to the current sampling time is obtained; the range of all the mean values ​​of the elements corresponding to the current sampling time is calculated and denoted as the first range value; the similarity coefficient of the current density sequences of all pairs of sensors at the current sampling time is obtained; the range value of all similarities obtained at the current sampling time is denoted as the second range value; the first range value and the second range value are accumulated, and combined with the current density difference value, the electroplating uniformity at the current sampling time is obtained. In this embodiment, the first range value is denoted as... The second range value is denoted as Let A be the difference in current density at the current moment. Then, the formula for the electroplating uniformity B at the current sampling moment is as follows: In the formula, norm() represents the normalization function, and A represents the difference in current density during the electroplating process of the titanium alloy workpiece at the current sampling time. This represents the range of the mean values ​​of all sensor current density sequences at the current sampling time. This represents the range of similarity coefficients for each pairwise combination of all sensors. It should be noted that the Pearson correlation coefficient is used in this embodiment, but the cosine similarity coefficient can also be used in other embodiments.

[0068] It should be understood that when affected by differences in the shape of the titanium alloy workpiece, the current density sequences reflected by the various electromagnetic sensors on the anode rod exhibit significant differences. Specifically, the fluctuations and magnitudes of the current density at the convex parts of the workpiece are much greater than those at other parts. Therefore, the greater the influence of the titanium alloy workpiece's shape, the greater the difference in the mean of the current density sequence and the similarity coefficient, indicating a lower uniformity in the electroplating process and requiring greater adjustments.

[0069] S3: Based on the difference in conductivity between the anode and cathode in the electroplating solution at each sampling time, the ion trend difference at each sampling time is obtained.

[0070] When titanium alloy workpieces are electroplated, the chromium ions in the original electroplating solution will be reduced by electrons and crystallize and precipitate onto the surface of the titanium alloy workpiece. Therefore, as electroplating proceeds, the metal ions in the solution will undergo differential transformation, that is, ion distribution differences will appear in the electroplating solution, resulting in uneven ion distribution, which further affects the movement and transfer of ions in the electroplating solution.

[0071] The most direct way to understand ion changes is through compositional analysis of the anode and cathode plating solutions using data acquisition equipment. However, real-time acquisition of plating components during the plating process has a certain lag, which is not conducive to real-time adjustment of the current density during plating. This application uses a conductivity analyzer to collect the anodic and cathode conductivity at each sampling time at the anode and cathode, and uses the conductivity to reflect the ion changes at the anode and cathode.

[0072] Specifically, the ion trend difference C at each sampling time during the electroplating process is obtained: In the formula, C represents the difference in ion trend in the electroplating solution at each sampling time. and These represent the trend intensity of the anodic conductivity sequence and the cathode conductivity sequence at each sampling time. It should be noted that the conductivity sequence is obtained in the same way as the current density sequence; the trend intensity of the sequence is calculated by using sequence decomposition to obtain the trend term and substituting it into the trend intensity formula; sequence decomposition and trend intensity calculation are well-known techniques and will not be elaborated upon in this application.

[0073] During electroplating, the electroplating power source generates electrons, metal ions are deposited at the cathode, and oxidation and dissolution occur at the anode. Theoretically, the conductivity of the anode and cathode in the electroplating solution should change synchronously. However, in actual operation, due to uneven current density or the influence of metal ion migration and deposition, the ion concentration at the anode and cathode will differ, resulting in an uneven ion concentration distribution. The greater the difference in ion trend in the conductivity sequence between the anode and cathode, the more necessary it is to appropriately increase the current density to promote the movement of charged particles between the anode and cathode.

[0074] S4: Based on the electroplating uniformity and ion trend difference at each sampling time, obtain the adjustment coefficient of the electroplating current at each sampling time, and adjust the electroplating current at each sampling time.

[0075] The current density during the electroplating process of titanium alloys can be analyzed by examining the uniformity of electroplating and the differences in ion trend. This allows for the determination of adjustments to the current density, resulting in an adjustment coefficient for the electroplating current. The specific formula is as follows: In the formula, denoted by , C represents the adjustment coefficient of the plating current at the current sampling time, C represents the ionization trend difference at the current sampling time, B represents the plating uniformity value during the plating process at the current sampling time, and d represents the plating thickness at the current sampling time, measured based on the coulomb method in the STM B504-1990 (2002) standard. This represents half the target coating thickness (determined based on the actual situation of the titanium alloy workpiece); norm() represents the normalization function.

[0076] Based on the above analysis, when the uniformity of electroplating is poor, it is necessary to appropriately reduce the electroplating current value to achieve uniformity of the electroplated layer on the titanium alloy workpiece during the electroplating process. Conversely, when the ion distribution in the electroplating solution is uneven, it is necessary to increase the electroplating current to accelerate the movement speed of ions in the electroplating solution and improve the uniformity of ions in the electroplating solution. The effect of the electroplating stage is characterized by the fact that the coating thickness is closer to the target coating thickness and closer to the intermediate stage of electroplating. At this time, the electroplating current should be appropriately increased to speed up the electroplating process.

[0077] This allows for the adjustment of the electroplating current, specifically as follows: ,in and These are the electroplating current values ​​before and after adjustment at time t, respectively. This represents the current adjustment coefficient at time t. The step size indicates the adjustment increment, which is set to 5% of the maximum plating current during the electroplating process in this embodiment. It should be noted that the initial plating current curve in this embodiment starts with a minimum plating current of 15 A / dm². 2 The current is gradually increased to its maximum value using the Sigmod function, and then gradually decreased to its minimum plating current. It should be noted that the adjusted current value at each sampling time is adjusted based on the preset value at each sampling time and is independent of the previous time.

[0078] It should be understood that at a single sampling moment, when the current deviation, coating uniformity deviation, and trend deviation in the electroplating solution are large, the resulting adjustment coefficient is large. Therefore, the adjustment is made based on the original electroplating current value, increasing the electroplating current to improve the control effect on electroplating. However, at a single sampling moment, when the actual electroplating current differs from the overall required value, the resulting current adjustment coefficient is almost zero. Therefore, current control is still based on the original electroplating current value.

[0079] The target current value at each sampling time is obtained through the above processing, which is the adjusted electroplating current value. Based on the actual current value collected, the control signal is transmitted to the controller. The controller can dynamically adjust the output ammeter of the electroplating power supply according to the difference between the two, thereby realizing the dynamic adjustment of the current density during the electroplating process of titanium alloy workpieces.

[0080] Vacuum thermal diffusion: After electroplating, the titanium alloy workpiece is washed with water and then placed in a vacuum heat treatment furnace for coating stabilization. The temperature in the heat treatment furnace is controlled at 750℃ and the treatment time is 5 hours. After heat treatment, the titanium alloy workpiece is naturally cooled to room temperature under vacuum conditions.

[0081] Example 2

[0082] A surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces, applied in the field of titanium alloy surface treatment technology, see attached document. Figure 1 The process includes:

[0083] Sandblasting: Wet sandblasting is performed using sandblasting equipment. The sandblasting medium used is 54# white corundum. The sandblasting pressure is controlled within the range of 0.3~0.7MPa, the sandblasting angle is maintained between 50° and 85°, and the sandblasting time is controlled to be 80s.

[0084] Electrochemical degreasing: This process removes the oil film from titanium alloy workpieces using an electrochemical mixed solution. Specifically, the sandblasted titanium alloy workpiece is placed in a mixed solution of NaOH, Na₂CO₃·10H₂O, Na₃PO₄·12H₂O, and Na₂SiO₃. The concentrations of each component in this mixed solution are: NaOH 50 g / L, Na₂CO₃·10H₂O 60 g / L, Na₃PO₄·12H₂O 50 g / L, and Na₂SiO₃ 5 g / L. The temperature of the mixed solution is adjusted to 90℃, and the electrochemical degreasing time is set to 5 minutes. During the electrochemical degreasing process, the titanium alloy workpiece is placed at the cathode, and a steel plate is used as the anode. The voltage is controlled at 20V, and the current density is set to 5A / dm³. 2 After electrochemical degreasing, the product is washed with pure water for 5 minutes.

[0085] Hydrogenation: The titanium alloy workpiece is hydrogenated after water washing to improve its surface activity. The workpiece is placed in a mixed hydrogenation solution, specifically a mixture of HCl and H₂SO₄. The H₂SO₄ concentration is 2 g / ml, the HCl concentration is 1 g / ml, and the volume ratio of H₂SO₄ to HCl is controlled at 3:1. The total volume of the mixed hydrogenation solution is 2 L. The temperature of the mixed solution during hydrogenation is set at 25°C, and the hydrogenation time is set at 60 min.

[0086] Pre-plating nickel: Chromium plating is used on titanium alloy workpieces to improve their wear resistance and corrosion resistance. However, the bonding force between the titanium alloy and the chromium plating layer is weak, making the chromium plating layer easy to fall off. Therefore, an intermediate layer electroplating is required after chromium plating.

[0087] Therefore, the hydrogenated titanium alloy workpiece is first immersed in nickel. The titanium alloy workpiece is placed in a nickel mixed solution with NiCl2·6H2O of 25 g / L and H3PO4 of 1600 g / L. The temperature of the mixed solution during nickel immersion is 25℃ and the immersion time is 100 min.

[0088] After nickel immersion, pre-plating with nickel is performed. The electroplating solution for nickel plating is a mixed solution of NiCl2·6H2O with a concentration of 400 g / L and HCl with a concentration of 150 g / L. The temperature of the electroplating solution for pre-plating is set to 25℃. The titanium alloy workpiece is used as the cathode, and the pure nickel plate is used as the anode. The electroplating time is 2 minutes, and the current density is 8 A / dm³. 2 .

[0089] Hard chrome plating: Metallic chromium has high hardness, therefore, chrome plating on titanium alloys can effectively improve their wear resistance and corrosion resistance. The electroplating solution used for chrome plating is a mixed solution of CrO3, H2SO4, and Cr2O3, with concentrations of 300 g / L for CrO3, 5 g / L for H2SO4, and 5 g / L for Cr2O3. The electroplating temperature is set at 65℃, and the current density is set at 35 A / dm³. 2 The anode is made of titanium-platinum rod, and the cathode is made of titanium alloy workpiece. The electroplating time is 30 minutes. The current density is adjusted using the same method as in Example 1.

[0090] Vacuum thermal diffusion: After electroplating, the titanium alloy workpiece is washed with water and then placed in a vacuum heat treatment furnace for coating stabilization. The temperature in the heat treatment furnace is controlled at 720℃ and the treatment time is 5 hours. After heat treatment, the titanium alloy workpiece is naturally cooled to room temperature under vacuum conditions.

[0091] Example 3

[0092] A surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces, applied in the field of titanium alloy surface treatment technology, see attached document. Figure 1 The process includes:

[0093] Sandblasting: Wet sandblasting is performed using sandblasting equipment. The sandblasting medium used is 54# white corundum. The sandblasting pressure is controlled within the range of 0.3~0.7MPa, the sandblasting angle is maintained between 50° and 85°, and the sandblasting time is controlled at 60s.

[0094] Electrochemical degreasing: This process removes the oil film from titanium alloy workpieces using an electrochemical mixed solution. Specifically, the sandblasted titanium alloy workpiece is placed in a mixed solution of NaOH, Na₂CO₃·10H₂O, Na₃PO₄·12H₂O, and Na₂SiO₃. The concentrations of each component in this mixed solution are: NaOH 40 g / L, Na₂CO₃·10H₂O 48 g / L, Na₃PO₄·12H₂O 30 g / L, and Na₂SiO₃ 5 g / L. The temperature of the mixed solution is adjusted to 90℃, and the electrochemical degreasing time is set to 10 min. During the electrochemical degreasing process, the titanium alloy workpiece is placed at the cathode, and a steel plate is used as the anode. The voltage is controlled at 20V, and the current density is set to 5 A / dm³.2 After electrochemical degreasing, the product is washed with pure water for 5 minutes.

[0095] Hydrogenation: The titanium alloy workpiece is hydrogenated after water washing to improve its surface activity. The workpiece is placed in a mixed hydrogenation solution, specifically a mixture of HCl and H₂SO₄ with a concentration of 2 g / ml for both H₂SO₄ and HCl, and a volume ratio of 2:1. The total volume of the mixed hydrogenation solution is 2 L. The temperature of the solution is set at 20°C, and the hydrogenation time is set at 90 min.

[0096] Pre-plating nickel: Chromium plating is used on titanium alloy workpieces to improve their wear resistance and corrosion resistance. However, the bonding force between the titanium alloy and the chromium plating layer is weak, making the chromium plating layer easy to fall off. Therefore, an intermediate layer electroplating is required.

[0097] Therefore, the hydrogenated titanium alloy workpiece is first immersed in nickel. The titanium alloy workpiece is placed in a nickel mixed solution with NiCl2·6H2O of 20 g / L and H3PO4 of 1400 g / L. The temperature of the mixed solution during nickel immersion is 25℃ and the immersion time is 150 min.

[0098] After immersion in nickel, pre-plating with nickel is performed. The electroplating solution for nickel plating is a mixed solution of NiCl2·6H2O with a concentration of 280 g / L and HCl with a concentration of 170 g / L. The temperature of the electroplating solution for pre-plating is set to 20℃. The titanium alloy workpiece is used as the cathode, and the pure nickel plate is used as the anode. The electroplating time is 5 min, and the current density is 5 A / dm³. 2 .

[0099] Hard chrome plating: Chromium has high hardness, therefore, chrome plating on titanium alloys can effectively improve their wear resistance and corrosion resistance. The electroplating solution used for chrome plating is a mixed solution of CrO3, H2SO4, and Cr2O3, with concentrations of 270 g / L for CrO3, 4 g / L for H2SO4, and 3 g / L for Cr2O3. The electroplating temperature is set at 65℃, and the current density is set at 20 A / dm³. 2 The anode is made of titanium-platinum rod, and the cathode is made of titanium alloy workpiece. The electroplating time is 90 minutes. The current density is adjusted using the same method as in Example 1.

[0100] Vacuum thermal diffusion: After electroplating, the titanium alloy workpiece is washed with water and then placed in a vacuum heat treatment furnace for coating stabilization. The temperature in the heat treatment furnace is controlled at 760℃ and the treatment time is 3 hours. After heat treatment, the titanium alloy workpiece is naturally cooled to room temperature under vacuum conditions.

[0101] To verify the effectiveness of this solution, the titanium alloys obtained through comparative examples were tested to validate the effectiveness of this solution.

[0102] Comparative Example 1: The current density is controlled by the minimum current density in the initial stage, the maximum current density in the middle stage, and the minimum current density in the later stage, which is the traditional current density control method.

[0103] Comparative Example 2: Electroplating was performed at the maximum current density throughout the entire electroplating stage, and its parameter information was consistent with that of Example 1 of this application.

[0104] Comparative Example 3: Electroplating was performed at the minimum current density throughout the entire electroplating stage, and its parameter information was consistent with that of Example 1 of this application.

[0105] During the electroplating process, the electroplating time and coating thickness are used as termination conditions; electroplating is terminated when either one is reached. The coating qualification, hardness, and uniformity error of the titanium alloy workpieces in this embodiment and comparative embodiments 1, 2, and 3 are obtained using professional measuring instruments, as shown in Table 1.

[0106] Table 1: Experimental Comparison

[0107]

[0108] Comparative experimental analysis shows that the electroplating process for titanium alloy workpieces using this scheme can effectively improve the pass rate during the electroplating process. Furthermore, hard chrome plating can greatly improve the hardness of titanium alloy workpieces, enhance the overall wear resistance and corrosion resistance of the workpieces, and result in a smaller overall uniformity error.

[0109] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than that shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different blocks may also occur in a different order than disclosed in the description; sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. Each block in a block diagram and / or flowchart, and combinations of blocks in a block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0110] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces, characterized in that, The process includes: After sandblasting, the titanium alloy workpiece is placed in an electrochemical mixture as a cathode to remove the oil film, and then hydrogenated after washing with water. After the hydrogenated titanium alloy workpiece is immersed in nickel, it is used as the cathode for pre-nickel plating. Then, the anode material and electroplating solution are changed to chromium plating the titanium alloy workpiece. During the electroplating process, the current density at each preset position of the anode at each sampling time is obtained; the conductivity of the anode and cathode is collected. Analyze the overall distribution characteristics of current density at all locations of the anode at each sampling time, and determine the difference in current density at each sampling time; A time window is preset for each sampling moment. The differences in current density distribution between all pairs of positions within the time window are analyzed. Based on the current density difference value, the electroplating uniformity at each sampling moment is determined. Sequences of conductivity at all sampling times within each sampling time window for both the anode and cathode are obtained. Each conductivity sequence is decomposed to obtain a trend term, which is then substituted into the trend intensity formula to obtain the trend intensity of the anode and cathode conductivity at each sampling time. The absolute value of the difference between the two is taken as the ion trend difference at each sampling time. Calculate the absolute value of the difference between the coating thickness at each sampling time and half of the target coating thickness, and sum it with the electroplating uniformity. The ratio of the ion trend difference at each sampling time to the obtained sum value is normalized to obtain the current adjustment coefficient at each sampling time. The product of the current adjustment coefficient at each sampling time and the preset adjustment step size is added to the preset electroplating current value at each sampling time to obtain the adjusted electroplating current value at each sampling time. After electroplating, the titanium alloy workpiece is washed with water to stabilize the coating.

2. The surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces as described in claim 1, characterized in that, The electrochemical mixture is specifically a mixed solution of NaOH, Na2CO3·10H2O, Na3PO4·12H2O, and Na2SiO3; wherein the concentrations of each component in the electrochemical mixture are: NaOH 25~50 g / L, Na2CO3·10H2O 30~60 g / L, Na3PO4·12H2O 20~50 g / L, and Na2SiO3 5~10 g / L; the anode material used in the oil film removal process is a steel plate, the temperature is 70~90℃, and the time is 5~15 min.

3. The surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces as described in claim 1, characterized in that, The specific operation of hydrogenation after water washing is as follows: the water-washed titanium alloy workpiece is placed in a mixed hydrogenation solution, which is a mixed solution of HCl and H2SO4, wherein the concentration of H2SO4 is 1~2g / ml, the concentration of HCl is 1~2g / ml, and the volume ratio of H2SO4 to HCl solution is between 2:1 and 3:

1. The total volume of the hydrogenation solution is 2L, the temperature of the mixed solution during hydrogenation is 15~25℃, and the hydrogenation time is 60~100min.

4. The surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces as described in claim 1, characterized in that, The specific operation of the nickel immersion treatment is as follows: the titanium alloy workpiece is placed in a nickel mixed solution, wherein the concentrations of each component in the nickel mixed solution are: NiCl2·6H2O is 10~25g / L and H3PO4 is 1400~1600g / L; the temperature during nickel immersion is 15~25℃ and the duration is 100~150min.

5. The surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces as described in claim 1, characterized in that, The electroplating solution for pre-plating nickel is a mixed solution of NiCl2·6H2O with a concentration of 200-400 g / L and HCL with a concentration of 150-200 g / L, the temperature for pre-plating nickel is 15-25℃, the titanium alloy workpiece is set as cathode, a pure nickel plate is an electroplating anode, the electroplating time is 2-5 min, and the current density is 4-8 A / dm 2 .

6. The surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces as described in claim 1, characterized in that, The electroplating solution for chromium plating on titanium alloy workpieces is a mixed solution of CrO3, H2SO4, and Cr2O3, with concentrations of 200-300 g / L for CrO3, 2-5 g / L for H2SO4, and 2-5 g / L for Cr2O3, respectively. The electroplating temperature is 45-65℃, and the current density is 15-35 A / dm³. 2 ; The anode is made of titanium-platinum rod, and the electroplating time is 30~150 minutes.

7. The surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces as described in claim 1, characterized in that, Determining the current density difference value at each sampling time includes: Obtain the standard deviation and kurtosis of the current density at all locations at each sampling time; The negative correlation mapping result of the kurtosis at each sampling time is positively fused with the standard deviation to obtain the current density difference value at each sampling time.

8. The surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpieces as described in claim 1, characterized in that, The determination of electroplating uniformity at each sampling time is specifically as follows: The sequence of current density values ​​at all sampling times within the time window corresponding to the current sampling time at each location is denoted as the current density sequence. Obtain the mean value of each current density sequence corresponding to the current sampling time, calculate the range of all the mean values ​​of the elements corresponding to the current sampling time, and record it as the first range value; obtain the similarity coefficient of the current density sequences of all pairs of sensors at the current sampling time; record the range of all similarities obtained at the current sampling time as the second range value; after accumulating the first range value and the second range value, and combining them with the current density difference value, obtain the electroplating uniformity at the current sampling time.

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