Surface treatment process for obtaining wear-resistant and corrosion-resistant titanium alloy workpiece

Abstract

The invention relates to the technical field of titanium alloy surface treatment, in particular to a surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece, which comprises the following steps: carrying out sand blasting treatment on the titanium alloy workpiece, placing the titanium alloy workpiece as a cathode in an electrochemical mixed solution to remove an oil film, washing with water, and hydrogenating; after the hydrogenated titanium alloy workpiece is subjected to nickel dipping treatment and serves as a cathode for nickel pre-plating, an anode material and electroplating liquid are replaced for chromium plating of the titanium alloy workpiece; in the electroplating process, the current density of the anode at each sampling moment and the conductivity of the anode and the cathode are analyzed, and the electroplating current at each sampling moment is adjusted; and after electroplating is completed, the titanium alloy workpiece is washed with water and then plated layer stabilization is conducted. The purpose of the invention is to improve the uniformity and corrosion resistance of an electroplated layer.

Description

Technical Field

[0001] The present application relates to the technical field of titanium alloy surface treatment, and in particular to a surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece. Background Art

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

[0003] The current processing technologies for titanium alloy workpieces mainly include: mechanical polishing, chemical mechanical polishing, cold treatment, heat treatment, sandblasting surface treatment and electroplating. Among them, the electroplating process can isolate the titanium alloy substrate from direct contact with the corrosive environment, and can improve the wear resistance and corrosion resistance of the titanium alloy workpiece. When electroplating titanium alloys, the connection tightness between the titanium alloy workpiece substrate and the coating is improved by pre-treating the titanium alloy workpiece. During the electroplating process, the current density is a key factor affecting the titanium alloy coating. If the current density is too low, it will lead to insufficient deposition of the coating, resulting in coarse crystals and poor corrosion resistance. If the current density is too high, it is easy for the coating to burn or dendrites to grow due to insufficient ion diffusion.

[0004] Currently, current density control during the electroplating process relies on preset parameter information. In the initial stages of electroplating, the current density is low, ensuring uniform distribution of metal ions in the coating. In the middle stages of electroplating, the current density is increased to accelerate the plating speed. In the latter stages of electroplating, the current density is reduced to improve coating uniformity. While this treatment can improve coating uniformity to a certain extent and enhance the wear and corrosion resistance of titanium alloy workpieces, the changes in current density are unrelated. Consequently, sudden changes in current density can lead to sudden changes in the grain size of the coating, affecting the integrity of the coating and reducing the protective effect of the electroplated layer 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 a wear-resistant and corrosion-resistant titanium alloy workpiece to solve the above problems.

[0006] One embodiment of the present application provides a surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece, the process comprising: After sandblasting, the titanium alloy workpiece is placed as a cathode in an electrochemical mixture to remove the oil film, and then hydrogenated after water washing; After the hydrogenated titanium alloy workpiece is subjected to nickel immersion treatment, it is pre-nickel plated as a cathode, and then the anode material and the electroplating solution are replaced to plate chromium on the titanium alloy workpiece; During the electroplating process, the current density of each preset position of the anode at each sampling moment is obtained; the conductivity of the anode and cathode is collected; Analyze the overall distribution characteristics of the current density at all positions of the anode at each sampling moment and determine the current density difference value at each sampling moment; Preset a time window for each sampling moment, analyze the difference characteristics between the current density distributions at all two combinations of positions within the time window, and determine the electroplating uniformity at each sampling moment based on the current density difference values; According to the difference characteristics between the conductivity of the anode and cathode in the electroplating solution at each sampling moment, the ion trend difference at each sampling moment is obtained; Based on the electroplating uniformity and ion trending differences at each sampling moment, the adjustment coefficient of the electroplating current at each sampling moment is obtained, and the electroplating current at each sampling moment is adjusted; After electroplating, the titanium alloy workpiece is washed with water and the coating is stabilized.

[0007] The electrochemical mixed solution is specifically a mixed solution of NaOH, Na2CO3·10H2O, Na3PO4·12H2O, and Na2SiO3; the concentrations of the components of the electrochemical mixed solution are: NaOH is 25~50g / L, Na2CO3·10H2O is 30~60g / L, Na3PO4·12H2O is 20~50g / L, and Na2SiO3 is 5~10g / L; the anode material in the oil film removal operation is steel plate, the temperature is 70~90℃, and the time is 5~15min.

[0008] Among them, the specific operation of hydrogenation after water washing is: placing the washed titanium alloy workpiece in a mixed hydrogenation solution, wherein the hydrogenation solution is specifically 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 solution volume ratio of H2SO4 and HCL is between 2:1~3:1, the total volume of the hydrogenation solution is 2L, the temperature of the mixed solution during hydrogenation is 15~25°C, and the hydrogenation time is 60~100min.

[0009] The specific operation of the nickel immersion treatment is as follows: placing the titanium alloy workpiece in a nickel mixed solution, wherein the concentrations of the components in the nickel mixed solution are: NiCl2·6H2O is 10~25g / L, H3PO4 is 1400~1600g / L; the temperature during nickel immersion is 15~25℃, and the duration is 100~150min.

[0010] The pre-nickel plating solution is a mixed solution of NiCl2·6H2O with a concentration of 200~400g / L and HCL with a concentration of 150~200g / L. The pre-nickel plating temperature is 15~25°C. The titanium alloy workpiece is set as the cathode and the pure nickel plate is the electroplating anode. The electroplating time is 2~5min and the current density is 4~8A / dm 2 .

[0011] The chromium plating solution for the titanium alloy workpiece is a mixed solution of CrO3, H2SO4, and Cr2O3, with concentrations of 200-300 g / L CrO3, 2-5 g / L H2SO4, and 2-5 g / L Cr2O3. The electroplating temperature is 45-65°C, and the current density is 15-35 A / dm 2 ; The anode is made of titanium platinum rod material, and the electroplating time is 30~150min.

[0012] The determining of the current density difference value at each sampling moment includes: Obtain the standard deviation and kurtosis of the current density at all locations at each sampling moment; The negative correlation mapping result of the kurtosis corresponding to each sampling moment is forwardly fused with the standard deviation to obtain the current density difference value at each sampling moment.

[0013] The current density difference value at each sampling moment is determined as follows: The sequence of current density values ​​at all sampling moments in the time window corresponding to the current sampling moment of each position is recorded as the current density sequence; Obtain the element mean of each current density sequence corresponding to the current sampling moment, calculate the range value of all the element means corresponding to the current sampling moment, and record it as the first range value; obtain the similarity coefficient of the current density sequence of all two combinations of sensors at the current sampling moment; record the range value of all similarities obtained at the current sampling moment as the second range value; after accumulating the first range value and the second range value, combine them with the current density difference value to obtain the electroplating uniformity at the current sampling moment.

[0014] The ion trend difference at each sampling moment is obtained as follows: Obtain a sequence consisting of the conductivity of the anode and cathode at all sampling moments in the time window of each sampling moment; decompose each conductivity sequence to obtain a trend term, substitute it into the trend intensity formula to obtain the trend intensity of the anode conductivity and cathode conductivity at each sampling moment, and take the absolute value of the difference between the two as the ion trend difference at each sampling moment.

[0015] The specific process of obtaining the adjustment coefficient of the electroplating current at each sampling moment and adjusting the electroplating current at each sampling moment is as follows: Calculating the absolute value of the difference between the coating thickness at each sampling moment and half the target coating thickness, and summing the difference with the electroplating uniformity; The ratio of the ion trend difference at each sampling moment to the obtained sum value is normalized to obtain the current adjustment coefficient at each sampling moment; The product of the current adjustment coefficient at each sampling moment and the preset adjustment step length is added to the preset electroplating current value at each sampling moment to obtain the adjusted electroplating current value at each sampling moment.

[0016] This application has at least the following beneficial effects: This application can improve the roughness and adhesion of the titanium alloy surface through steps such as sandblasting, oil film removal, hydrogenation, nickel immersion and pre-nickel plating, laying the foundation for the subsequent chrome plating process. These treatment processes help to ensure that the chrome plating layer is uniform and firm, improve the wear resistance, high temperature resistance and corrosion resistance of the titanium alloy workpiece, extend its service life and improve its overall performance; further, in this application, by analyzing the current density distribution characteristics of the anode position at each sampling moment, it is possible to identify the difference in current density, thereby optimizing the electroplating process and ensuring that the electroplating layer is evenly distributed over the entire workpiece surface; at the same time, combined with the conductivity difference characteristics, the electroplating current is dynamically adjusted, which helps to correct the unevenness in the electroplating process in real time, improve the electroplating quality and the performance of the workpiece surface, enhance the corrosion resistance, wear resistance and other characteristics of the workpiece, and extend the service life. The water washing process can remove the residual plating solution and impurities on the surface, reduce pollutants that may affect the quality of the coating, and ensure that the coating is more uniform and smooth. The subsequent coating stabilization treatment helps to strengthen the density and corrosion resistance of the coating, thereby improving the performance of the titanium alloy workpiece, enhancing its wear resistance, high temperature resistance and corrosion resistance, and ensuring its long-term stability and reliability in practical applications. Finally, through comparative analysis of the examples, the electroplating surface treatment process of the present application can effectively improve the uniformity and corrosion resistance of the electroplated coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of a surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece provided in this application; Figure 2 Schematic diagram of current density parameter information collection provided for this application. DETAILED DESCRIPTION

[0018] In the description of the embodiments of this application, words such as "exemplary," "or," and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "or," and "for example" is intended to present the relevant concepts in a concrete manner.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the art of this application. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0020] 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 precedence. The methods disclosed in the embodiments of this application or the methods shown in the flowcharts include one or more steps for implementing the methods. Without departing from the scope of protection of this application, the order of execution of multiple steps can be interchanged with each other, and some steps can also be deleted.

[0021] Unless defined otherwise, 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.

[0022] Example 1 Titanium and titanium alloys are often highly active and easily react with oxygen in the air, quickly forming a dense oxide film on the surface. This oxide film has high chemical stability and insulation, which hinders the adhesion of metal ions on the titanium alloy workpiece during the electroplating process and affects the bonding between the coating and the substrate. Therefore, the titanium alloy workpiece needs to be surface pretreated before electroplating.

[0023] Sandblasting: Wet sandblasting is performed using sandblasting equipment. The blasting medium used in the sandblasting process is 54# white corundum. The sandblasting pressure is controlled within the range of 0.3~0.7MPa, the sandblasting angle is maintained between 50°~85°, and the sandblasting time is controlled at 30s.

[0024] Electrochemical degreasing: The oil film on the titanium alloy workpiece is removed by using an electrochemical mixed solution. Specifically, the titanium alloy workpiece after sandblasting is placed in a mixed solution of NaOH, Na2CO3·10H2O, Na3PO4·12H2O, and Na2SiO3. The concentrations of the components of the mixed solution are: NaOH is 25g / L, Na2CO3·10H2O is 30g / L, Na3PO4·12H2O is 20g / L, and Na2SiO3 is 10g / L; the temperature of the mixed solution is adjusted to 70°C, and the electrochemical degreasing time is adjusted to 15min. During the electrochemical degreasing process, the titanium alloy workpiece is placed at the cathode, the steel plate is used as the anode, the voltage is controlled at 25V, and the current density is set to 10A / dm 2 After electrochemical degreasing, it is washed with pure water for 5 minutes.

[0025] Hydrogenation: The titanium alloy workpiece after water washing is hydrogenated to improve the surface activity of the titanium alloy workpiece. The titanium alloy workpiece is placed in a mixed hydrogenation solution for hydrogenation. Specifically, it is placed in a mixed solution of HCl and H2SO4. The specific concentration of the solution is 1g / ml H2SO4 and 2g / ml HCL. The volume ratio of H2SO4 to HCl is controlled to be 2:1. The total volume of the mixed hydrogenation solution is prepared to be 2L. The temperature of the mixed solution during hydrogenation is set to 15°C and the hydrogenation time is set to 100 minutes.

[0026] Pre-nickel plating: Chrome plating is used on titanium alloy workpieces to improve the wear resistance and corrosion resistance of titanium alloy workpieces. However, the bonding force between the titanium alloy and the chrome plating layer is weak, making the chrome plating layer easy to fall off, so intermediate layer electroplating is required.

[0027] Therefore, the hydrogenated titanium alloy workpiece is first immersed in nickel, and the titanium alloy workpiece is placed in a nickel mixed solution, in which NiCl2·6H2O is 10g / L and H3PO4 is 1400g / L. The temperature of the mixed solution during nickel immersion is 15°C, and the nickel immersion time is 150min.

[0028] After nickel immersion, pre-nickel plating is performed. The plating solution is a mixed solution of NiCl2·6H2O with a concentration of 200g / L and HCL with a concentration of 150g / L. The plating solution temperature is set to 15°C during pre-nickel plating. The titanium alloy workpiece is set as the cathode and the pure nickel plate is the electroplating anode. The electroplating time is 5 minutes and the current density is 4A / dm 2 .

[0029] Hard chromium plating: Chromium metal has a high hardness, so chromium plating on titanium alloy can effectively improve the wear resistance and corrosion resistance of titanium alloy. The electroplating solution for chromium plating is a mixed solution of CrO3, H2SO4, and Cr2O3. The concentrations are: CrO3 is 200g / L, H2SO4 is 2g / L, and Cr2O3 is 2g / L. The electroplating temperature is set to 45°C and the current density is set to 15A / dm 2 The anode is made of titanium platinum rod (the surface of the titanium alloy rod has a layer of platinum of 1~3um), the cathode is made of titanium alloy workpiece, and the electroplating time is 150 minutes.

[0030] By electroplating hard chromium on the surface of titanium alloy, the overall wear resistance and corrosion resistance of the titanium alloy workpiece can be improved. During the electroplating process, the current density is directly related to the surface of the titanium alloy workpiece. By controlling the current density, a dense and uniform electroplating layer can be formed.

[0031] In the traditional electroplating process, the entire electroplating stage is divided into three stages according to time. In this embodiment, the initial stage is 20%, the middle stage is 50%, and the late stage is 30%. A fixed current density is set for each stage based on the empirical value. When the electroplating time ends or the monitored electroplating thickness reaches the target requirement, the electroplating can be stopped. This can easily cause defects such as inconsistent bonding force and uneven electroplating 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: S1: During the electroplating process, the current density at each preset position of the anode at each sampling moment is obtained; the conductivity of the anode and cathode is collected.

[0032] During the electroplating process, current density affects the grain size of electroplated chromium and the uniformity of the coating. Therefore, it is necessary to measure the current density parameter information of the electroplating process in real time. Figure 2 As shown, N magnetic current sensors are evenly placed on the surface of the anode titanium platinum rod and connected to a digital operator to measure the current density on the electrode. The measurement principle refers to the reference "Design of an online monitoring system for current density during barrel plating". At the same time, an ammeter is connected to the anode to measure the overall current output.

[0033] In addition, during the electroplating process, as the plating layer continues to thicken, the ion concentration distribution in the plating solution changes, further affecting the transfer of current density. In order to further characterize the degree of change in ion concentration, the probes of the conductivity meter are deployed at the anode titanium-platinum rod and the cathode titanium alloy workpiece respectively to measure the conductivity of the plating solution around the anode and cathode, thereby reflecting the difference in ion distribution in the plating solution.

[0034] All the above sensors are connected to a digital operator to achieve digital-to-analog conversion and signal amplification. In this embodiment, the sampling interval of all data sensors is set to be consistent, specifically once every 200ms, and the number of magnetic sensitive current sensors is set to 12.

[0035] Thus, the real-time collection of electroplating parameters during the chromium electroplating process on titanium alloy is achieved.

[0036] S2: Analyze the overall distribution characteristics of the current density at all positions of the anode at each sampling moment, and determine the current density difference value at each sampling moment.

[0037] During the electroplating process, current density is a key factor affecting plating quality. High current density promotes rapid reduction of metal ions and rapidly increases coating thickness, but it can also lead to coarse grains and burnt pitting on the surface. Low current density, on the other hand, produces finer, smoother, denser coatings with lower porosity, but this results in lower plating efficiency, impacting production efficiency.

[0038] During the electroplating process of titanium alloy workpieces, the electroplating power supply, anode and cathode, and electroplating solution form a closed loop, and the cathode titanium alloy workpiece needs to be electroplated. Therefore, a sensor is placed on the anode titanium-platinum rod to collect the current density at various positions on the anode, so as to estimate the current density distribution of the titanium alloy workpiece.

[0039] At a single sampling moment, there are N magnetic induction current sensors. By analyzing the changes in the magnetic signal, the current density at the position of the anode rod can be determined. Rationally, 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 smaller range, showing a normal distribution with a small overall deviation.

[0040] According to the current density value changes collected by each magnetic induction current sensor at the current sampling moment, the current density difference value at the current sampling moment is obtained , its formula form is: , where A represents the current density difference during the electroplating process of the titanium alloy workpiece at the current sampling moment, and H represent the standard deviation and kurtosis of the current density collected by N sensors at the current sampling moment, exp() represents the exponential function with the natural constant e as the base, Represents the kurtosis adjustment parameter, which is set to 3, since the kurtosis of the standard normal distribution is 3.

[0041] Analysis of the current density distribution differences at the current sampling moment shows that, under normal circumstances, ambient noise often exhibits a normal distribution. Consequently, during the actual acquisition process, current density fluctuations are small, the standard deviation is small, and the kurtosis distribution differs little from the standard normal distribution, ultimately resulting in a small current density difference. Conversely, a large current density difference at the current sampling moment indicates that the current value of the electroplating process under this state does not match the actual electroplating process, and adjustment is likely required.

[0042] The current density difference value is 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 the electroplating process, 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 titanium alloy workpiece shape on the current density distribution, so it may differ from the actual electroplating process.

[0043] S2: Preset a time window for each sampling moment, analyze the difference characteristics between the current density distributions at all two combinations of positions within the time window, and determine the electroplating uniformity at each sampling moment based on the current density difference value.

[0044] During the wear-resistant and corrosion-resistant processing of titanium alloy workpieces, they must be finished workpieces, so they have certain shape and structural characteristics. These external structural characteristics are likely to affect the magnitude of the current density. Therefore, it is necessary to combine the spatial distribution state of the electromagnetic sensor on the anode rod to realize the evaluation of the electroplating uniformity.

[0045] During the electroplating process, W sampling moments ahead of the current sampling moment are selected as the evaluation time window. Based on experimental analysis, the value of W preferably ranges from 50 to 80. In this embodiment, W is 50. The sequence consisting of the 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.

[0046] During the electroplating process, because the titanium-platinum anode rod is a uniform rod and the titanium alloy workpiece has a certain shape and structural characteristics, the closer the anode rod is to the protruding part of the titanium alloy workpiece, the smaller the corresponding internal resistance value. As a result, the current density value at the protruding part is larger and fluctuates greatly as the current density increases. For other parts of the titanium alloy workpiece, the current density value at the corresponding anode rod position is smaller, and the current density fluctuates less with changes in the overall electroplating current.

[0047] Based on this, the electroplating uniformity at the current sampling moment is obtained. Specifically: obtain the element mean of each current density sequence corresponding to the current sampling moment, calculate the range value of all the element means corresponding to the current sampling moment, and record it as the first range value; obtain the similarity coefficient of the current density sequence of all sensors in pairs at the current sampling moment; record the range value of all similarities obtained at the current sampling moment as the second range value; after accumulating the first range value and the second range value, combine them with the current density difference value to obtain the electroplating uniformity at the current sampling moment. In this embodiment, the first range value is recorded as , and record the second extreme difference as ; Let the current density difference at the current moment be recorded as A, then the formula for the electroplating uniformity B at the current sampling moment is specifically: ; In the formula, norm() represents the normalization function, A represents the current density difference value of the titanium alloy workpiece during the electroplating process at the current sampling moment, Represents the extreme value of the mean value of the current density series of all sensors at the current sampling moment, It should be noted that the similarity coefficient in this embodiment uses the Pearson correlation coefficient, and in other embodiments, the cosine similarity coefficient can also be used.

[0048] It should be understood that when affected by the shape of the titanium alloy workpiece, the current density sequences reflected by the various electromagnetic sensors on the anode rod vary significantly. Specifically, the current density fluctuations and values ​​for the protruding parts of the workpiece are much greater than those for other parts of the workpiece. Therefore, the greater the influence of the titanium alloy workpiece's shape, the greater the difference in the mean and similarity coefficient of the corresponding current density sequences. This reflects that the uniformity of the workpiece electroplating during the titanium alloy electroplating process is lessened, and greater adjustments are required.

[0049] S3: Based on the difference characteristics between the conductivity of the anode and the cathode in the plating solution at each sampling moment, the ion trend difference at each sampling moment is obtained.

[0050] When titanium alloy workpieces are electroplated, the chromium ions originally in the plating solution will be reduced by electrons and crystallized and precipitated on the surface of the titanium alloy workpiece. Therefore, as the electroplating progresses, the metal ions in the solution will undergo differential changes, that is, differences in ion distribution will appear in the plating solution, resulting in uneven ion distribution, which further affects the movement and transfer of ions in the plating solution.

[0051] The most direct way to measure ion changes is to analyze the composition of the anode and cathode plating solutions using a collection device. However, during the electroplating process, real-time collection of plating components has a certain lag, which is not conducive to real-time adjustment of current density during the electroplating process. This application uses a conductivity analyzer to collect the anode conductivity and cathode conductivity at each sampling moment at the anode and cathode, and uses the conductivity to reflect the ion changes of the anode and cathode.

[0052] Specifically, obtain the ion trend difference C at each sampling moment during the electroplating process: , where C represents the trend difference of ions in the plating solution at each sampling moment, and Respectively represent the trend strength of the anode conductivity series and cathode conductivity series at each sampling moment. It should be noted that the conductivity series is obtained in the same manner as the current density series; the trend strength of the series is calculated by decomposing the series to obtain the trend term and substituting it into the trend strength formula. Sequence decomposition and trend strength calculation are well-known techniques and will not be further described in this application.

[0053] During the electroplating process, the electroplating power supply generates electrons, metal ion deposition occurs at the cathode, and oxidation and dissolution occur at the anode. Theoretically, the conductivity of the cathode and anode in the electroplating solution should change synchronously. However, in practice, due to uneven current density or the influence of metal ion migration and deposition, the ion concentrations of the anode and cathode may differ, resulting in an uneven ion concentration distribution. In this case, the greater the difference in the ion trend of the anode and cathode conductivity sequence, the more necessary it is to increase the current density to promote the movement of charged particles between the cathode and cathode.

[0054] S4: Based on the electroplating uniformity and ion trending differences at each sampling moment, an adjustment coefficient of the electroplating current at each sampling moment is obtained, and the electroplating current at each sampling moment is adjusted.

[0055] The current density of titanium alloy during the electroplating process can be analyzed by the electroplating uniformity and ion trend difference, so as to obtain the adjustment of current density and the adjustment coefficient of electroplating current. The specific formula is: Where, represents the adjustment coefficient of the electroplating current at the current sampling moment, C represents the ion trend difference at the current sampling moment, B represents the electroplating uniformity value during the electroplating process at the current sampling moment, and d represents the thickness of the electroplated coating at the current sampling moment, which is measured based on the Coulomb method in the STM B504-1990 (2002) standard. It represents half of the target coating thickness (determined according to the actual situation of the titanium alloy workpiece); norm() represents the normalization function.

[0056] After the above analysis, when the uniformity of electroplating is worse, it is necessary to appropriately reduce the electroplating current value to achieve the uniformity of the electroplating layer of the titanium alloy workpiece during the electroplating process. When the ions in the electroplating solution are unevenly distributed, it is necessary to increase the electroplating current to speed up the movement of ions in the electroplating solution and improve the uniformity of ions in the electroplating solution. Characterize the influence of the electroplating stage. The closer the coating thickness is to the target coating thickness, the closer it is to the middle stage of electroplating. At this time, the electroplating current should be appropriately increased to speed up the electroplating speed.

[0057] This is how the electroplating current is adjusted, specifically: ,in and are the electroplating current values ​​before and after adjustment at time t, Indicates the current adjustment coefficient at time t, Indicates the adjustment step size, which is set to 5% of the maximum plating current during the plating process in this embodiment. It should be noted that the initial plating current curve in this embodiment is that the minimum plating current is 15A / dm 2 , gradually increases to the maximum value in the form of Sigmod function, and then gradually decreases to the minimum electroplating current; it should be noted that the adjusted current value at each sampling moment is adjusted based on the preset value at each sampling moment and has nothing to do with the previous moment.

[0058] It should be understood that when the current deviation, coating uniformity deviation, and trend deviation in the plating solution are large at a single sampling moment, the resulting adjustment coefficient is large. Therefore, adjustments are made to the original set plating current value to increase the plating current and improve the control effect of the plating. On the other hand, when the overall difference between the actual plating current and the actual requirement is small at a single sampling moment, the value of the current adjustment coefficient is almost zero, so the current control is still based on the original set plating current value.

[0059] The target current value at each sampling moment, i.e., the adjusted electroplating current value, is obtained through processing in the above manner; based on the actual current value obtained, the control signal is transmitted to the controller, and the controller can dynamically adjust the output ammeter of the electroplating power supply according to the difference between the two, thereby realizing dynamic adjustment of the current density during the electroplating process of the titanium alloy workpiece.

[0060] Vacuum thermal diffusion: After the electroplating is completed, the titanium alloy workpiece is washed with water, and then placed in a vacuum heat treatment furnace to stabilize the coating. The temperature in the heat treatment furnace is controlled to 750°C, and the treatment time is 5 hours. After the heat treatment is completed, the titanium alloy workpiece is naturally cooled to room temperature under vacuum conditions.

[0061] Example 2 A surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece, which is applied to the technical field of titanium alloy surface treatment, Figure 1 , the process comprises: Sandblasting: Wet sandblasting is performed using sandblasting equipment. The blasting medium used in the sandblasting process is 54# white corundum. The sandblasting pressure is controlled within the range of 0.3~0.7MPa, the sandblasting angle is maintained between 50°~85°, and the sandblasting time is controlled at 80s.

[0062] Electrochemical degreasing: The oil film on the titanium alloy workpiece is removed by using an electrochemical mixed solution. Specifically, the titanium alloy workpiece after sandblasting is placed in a mixed solution of NaOH, Na2CO3·10H2O, Na3PO4·12H2O, and Na2SiO3. The concentrations of the components of the mixed solution are: NaOH is 50g / L, Na2CO3·10H2O is 60g / L, Na3PO4·12H2O is 50g / L, and Na2SiO3 is 5g / L; the temperature of the mixed solution is adjusted to 90°C, and the electrochemical degreasing time is adjusted to 5min. During the electrochemical degreasing process, the titanium alloy workpiece is placed at the cathode, the steel plate is used as the anode, the voltage is controlled at 20V, and the current density is set to 5A / dm 2 After electrochemical degreasing, it is washed with pure water for 5 minutes.

[0063] Hydrogenation: The titanium alloy workpiece after water washing is hydrogenated to improve the surface activity of the titanium alloy workpiece. The titanium alloy workpiece is placed in a mixed hydrogenation solution for hydrogenation. Specifically, it is placed in a mixed solution of HCl and H2SO4. The specific concentration of the solution is 2g / ml H2SO4, the concentration of HCl is 1g / ml, and the volume ratio of H2SO4 to HCl is controlled to be 3:1. The total volume of the mixed hydrogenation solution is prepared to be 2L. The temperature of the mixed solution during hydrogenation is set to 25°C, and the hydrogenation time is set to 60 minutes.

[0064] Pre-nickel plating: Chrome plating is used on titanium alloy workpieces to improve the wear resistance and corrosion resistance of titanium alloy workpieces. However, the bonding force between the titanium alloy and the chrome plating layer is weak, which makes the chrome plating layer easy to fall off, so an intermediate layer electroplating is required during the chrome plating.

[0065] Therefore, the hydrogenated titanium alloy workpiece is first immersed in nickel, and the titanium alloy workpiece is placed in a nickel mixed solution, in which NiCl2·6H2O is 25g / L and H3PO4 is 1600g / L. The temperature of the mixed solution during nickel immersion is 25°C, and the nickel immersion time is 100min.

[0066] After nickel immersion, pre-nickel plating is performed. The plating solution is a mixed solution of NiCl2·6H2O with a concentration of 400g / L and HCL with a concentration of 150g / L. The plating solution temperature is set to 25°C during pre-nickel plating. The titanium alloy workpiece is set as the cathode and the pure nickel plate is the electroplating anode. The electroplating time is 2 minutes and the current density is 8A / dm 2 .

[0067] Hard chromium plating: Chromium metal has a high hardness, so chromium plating on titanium alloy can effectively improve the wear resistance and corrosion resistance of titanium alloy. The electroplating solution for chromium plating is a mixed solution of CrO3, H2SO4, and Cr2O3. The concentrations are: CrO3 is 300g / L, H2SO4 is 5g / L, and Cr2O3 is 5g / L. The electroplating temperature is set to 65℃ and the current density is set to 35A / dm 2 The anode is made of titanium-platinum rod material, the cathode is made of titanium alloy workpiece, and the electroplating time is 30 minutes; wherein, the current density is adjusted using the same method as in Example 1.

[0068] Vacuum thermal diffusion: After the electroplating is completed, 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°C, and the treatment time is 5 hours. After the heat treatment is completed, the titanium alloy workpiece is naturally cooled to room temperature under vacuum conditions.

[0069] Example 3 A surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece, which is applied to the technical field of titanium alloy surface treatment, Figure 1 , the process comprises: Sandblasting: Wet sandblasting is performed using sandblasting equipment. The blasting medium used in the sandblasting process is 54# white corundum. The sandblasting pressure is controlled within the range of 0.3~0.7MPa, the sandblasting angle is maintained between 50°~85°, and the sandblasting time is controlled at 60s.

[0070] Electrochemical degreasing: The oil film on the titanium alloy workpiece is removed by using an electrochemical mixed solution. Specifically, the titanium alloy workpiece after sandblasting is placed in a mixed solution of NaOH, Na2CO3·10H2O, Na3PO4·12H2O, and Na2SiO3. The concentrations of the components of the mixed solution are: NaOH is 40g / L, Na2CO3·10H2O is 48g / L, Na3PO4·12H2O is 30g / L, and Na2SiO3 is 5g / L; the temperature of the mixed solution is adjusted to 90°C, and the electrochemical degreasing time is adjusted to 10min. During the electrochemical degreasing process, the titanium alloy workpiece is placed at the cathode, the steel plate is used as the anode, the voltage is controlled at 20V, and the current density is set to 5A / dm 2After electrochemical degreasing, it is washed with pure water for 5 minutes.

[0071] Hydrogenation: The titanium alloy workpiece after water washing is hydrogenated to improve the surface activity of the titanium alloy workpiece. The titanium alloy workpiece is placed in a mixed hydrogenation solution for hydrogenation. Specifically, it is placed in a mixed solution of HCl and H2SO4. The specific concentration of the solution is 2g / ml H2SO4, the concentration of HCl is 2g / ml, and the volume ratio of H2SO4 to HCl is controlled to be 2:1. The total volume of the mixed hydrogenation solution is prepared to be 2L. The temperature of the mixed solution during hydrogenation is set to 20°C and the hydrogenation time is set to 90 minutes.

[0072] Pre-nickel plating: Chrome plating is used on titanium alloy workpieces to improve the wear resistance and corrosion resistance of titanium alloy workpieces. However, the bonding force between the titanium alloy and the chrome plating layer is weak, making the chrome plating layer easy to fall off, so intermediate layer electroplating is required.

[0073] Therefore, the hydrogenated titanium alloy workpiece is first immersed in nickel, and the titanium alloy workpiece is placed in a nickel mixed solution, in which NiCl2·6H2O is 20g / L and H3PO4 is 1400g / L. The temperature of the mixed solution during nickel immersion is 25°C, and the nickel immersion time is 150min.

[0074] After nickel immersion, pre-nickel plating is performed. The plating solution is a mixed solution of NiCl2·6H2O with a concentration of 280 g / L and HCL with a concentration of 170 g / L. The plating solution temperature is set to 20 ° C during pre-nickel plating. The titanium alloy workpiece is set as the cathode and the pure nickel plate is the electroplating anode. The electroplating time is 5 min and the current density is 5 A / dm 2 .

[0075] Hard chromium plating: Metallic chromium has a high hardness, so chromium plating on titanium alloy can effectively improve the wear resistance and corrosion resistance of titanium alloy. The electroplating solution for chromium plating is a mixed solution of CrO3, H2SO4, and Cr2O3. The concentrations are: CrO3 is 270g / L, H2SO4 is 4g / L, and Cr2O3 is 3g / L. The electroplating temperature is set to 65℃ and the current density is set to 20A / dm 2 The anode is made of titanium-platinum rod material, the cathode is made of titanium alloy workpiece, and the electroplating time is 90 minutes; wherein, the current density is adjusted using the same method as in Example 1.

[0076] Vacuum thermal diffusion: After the electroplating is completed, 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°C, and the treatment time is 3 hours. After the heat treatment is completed, the titanium alloy workpiece is naturally cooled to room temperature under vacuum conditions.

[0077] In order to verify the effectiveness of this solution, the titanium alloy obtained by the comparative example was tested to verify the effectiveness of this solution.

[0078] Comparative Example 1: The current density is controlled at the minimum in the initial stage, the maximum in the middle stage, and the minimum in the late stage, i.e., the traditional current density control method; Comparative Example 2: Electroplating is performed at the maximum current density during the entire electroplating stage, and its parameter information remains consistent with that of Example 1 of the present application.

[0079] Comparative Example 3: Electroplating is performed at the minimum current density during the entire electroplating stage, and its parameter information remains consistent with that of Example 1 of the present application.

[0080] During the electroplating process, the electroplating time and the coating thickness are used as termination conditions. Electroplating can be terminated when either condition is reached. The coating qualification, hardness, and uniformity error of the titanium alloy workpieces of this embodiment and comparative examples 1, 2, and 3 are obtained by professional measuring instruments, as shown in Table 1.

[0081] Table 1: Experimental comparison Through comparative experimental analysis, it can be concluded that the surface electroplating treatment process of titanium alloy workpieces through this scheme can effectively improve the pass rate in the electroplating process, and electroplating hard chromium can greatly increase the hardness of titanium alloy workpieces, improve the overall wear resistance and corrosion resistance of the workpiece, and the overall uniform error is small.

[0082] The flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the systems, methods and computer program products according to the embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the part of the module, program segment or code contains one or more executable instructions for realizing the specified logical function. In some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. In the description corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different boxes can also occur in an order different from that disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. Each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that performs the specified function or action, or may be implemented by a combination of dedicated hardware and computer instructions.

[0083] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece, characterized in that: The process includes: After sandblasting, the titanium alloy workpiece is placed as a cathode in an electrochemical mixture to remove the oil film, and then hydrogenated after water washing; After the hydrogenated titanium alloy workpiece is subjected to nickel immersion treatment, it is pre-nickel plated as a cathode, and then the anode material and the electroplating solution are replaced to plate chromium on the titanium alloy workpiece; During the electroplating process, the current density of each preset position of the anode at each sampling moment is obtained; the conductivity of the anode and cathode is collected; Analyze the overall distribution characteristics of the current density at all positions of the anode at each sampling moment and determine the current density difference value at each sampling moment; Preset a time window for each sampling moment, analyze the difference characteristics between the current density distributions at all two combinations of positions within the time window, and determine the electroplating uniformity at each sampling moment based on the current density difference values; According to the difference characteristics between the conductivity of the anode and cathode in the electroplating solution at each sampling moment, the ion trend difference at each sampling moment is obtained; Based on the electroplating uniformity and ion trending differences at each sampling moment, the adjustment coefficient of the electroplating current at each sampling moment is obtained, and the electroplating current at each sampling moment is adjusted; After electroplating, the titanium alloy workpiece is washed with water and the coating is stabilized.

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

3. The surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece according to claim 1, characterized in that: The specific operation of hydrogenation after water washing is: placing the washed titanium alloy workpiece in a mixed hydrogenation solution, wherein the hydrogenation solution is specifically 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 solution volume ratio of H2SO4 and HCL is between 2:1~3:1, the total volume of the hydrogenation solution is 2L, the temperature of the mixed solution during hydrogenation is 15~25°C, and the hydrogenation time is 60~100min.

4. The surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece according to claim 1, characterized in that: The specific operation of the nickel immersion treatment is: placing the titanium alloy workpiece in a nickel mixed solution, wherein the concentrations of the components 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°C, and the duration is 100-150 minutes.

5. The surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece according to claim 1, characterized in that: The pre-nickel plating solution 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-nickel plating temperature is 15-25°C. The titanium alloy workpiece is set as the cathode and the pure nickel plate is set as the electroplating anode. The electroplating time is 2-5 minutes and the current density is 4-8 A / dm 2 .

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

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

8. The surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece according to claim 1, characterized in that: The current density difference value at each sampling moment is determined as follows: The sequence of current density values ​​at all sampling moments in the time window corresponding to the current sampling moment of each position is recorded as the current density sequence; Obtain the element mean of each current density sequence corresponding to the current sampling moment, calculate the range value of all the element means corresponding to the current sampling moment, and record it as the first range value; obtain the similarity coefficient of the current density sequence of all two combinations of sensors at the current sampling moment; record the range value of all similarities obtained at the current sampling moment as the second range value; after accumulating the first range value and the second range value, combine them with the current density difference value to obtain the electroplating uniformity at the current sampling moment.

9. The surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece according to claim 1, characterized in that: The ion trend difference at each sampling moment is obtained as follows: Obtain a sequence consisting of the conductivity of the anode and cathode at all sampling moments in the time window of each sampling moment; decompose each conductivity sequence to obtain a trend term, substitute it into the trend intensity formula to obtain the trend intensity of the anode conductivity and cathode conductivity at each sampling moment, and take the absolute value of the difference between the two as the ion trend difference at each sampling moment.

10. The surface treatment process for obtaining a wear-resistant and corrosion-resistant titanium alloy workpiece according to claim 1, characterized in that: The specific process of obtaining the adjustment coefficient of the electroplating current at each sampling moment and adjusting the electroplating current at each sampling moment is as follows: Calculating the absolute value of the difference between the coating thickness at each sampling moment and half the target coating thickness, and summing the difference with the electroplating uniformity; The ratio of the ion trend difference at each sampling moment to the obtained sum value is normalized to obtain the current adjustment coefficient at each sampling moment; The product of the current adjustment coefficient at each sampling moment and the preset adjustment step length is added to the preset electroplating current value at each sampling moment to obtain the adjusted electroplating current value at each sampling moment.

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