A method for sputtering coating of metal pipelines based on corrosion-resistant alloy targets

Abstract

The present invention relates to the technical field of metal pipeline surface treatment, and discloses a method for sputtering metal pipeline coatings based on a corrosion-resistant alloy target. The method comprises applying a first pulse sequence to the alloy target to sputter metal atoms, applying a second pulse sequence to the metal pipeline, and strictly synchronizing the two sequences so that negative voltage pulses are applied only during periods of low target power. The metal ions generated by sputtering are then used to bombard the densified deposited layer. By sequentially decoupling the metal atom deposition and ion bombardment steps, the present invention fundamentally resolves the re-sputtering contradiction caused by conventional continuous biasing, achieves independent control of the coating rate and film quality, and ensures process stability through a closed-loop feedback mechanism, significantly improving the consistency and reliability of coating performance.

Description

Technical Field

[0001] The invention relates to a metal pipeline sputtering coating method based on a corrosion-resistant alloy target material, and belongs to the technical field of metal pipeline surface treatment. Background Art

[0002] In the field of metal pipeline surface protection, magnetron sputtering technology has become the mainstream process for corrosion-resistant alloy coatings due to its excellent coating adhesion and density. The industry currently generally adopts the continuous bias sputtering method: by applying a constant negative bias to the pipeline workpiece, argon ions are attracted to bombard the deposited layer to optimize the film structure. This method performs stably on flat substrates. However, when applied to the inner wall of a metal pipeline with a large aspect ratio and variable curvature, its fundamental defects are significantly amplified under dynamic working conditions.

[0003] Taking the inner wall coating of petrochemical transmission pipelines as an example, this scenario requires that the coating remain intact for more than ten years under high pressure and corrosive media erosion. The existing technology faces three contradictions: 1. The electric field strength in the deep hole area of ​​the pipeline is attenuated, resulting in insufficient ion bombardment intensity and significantly weaker coating adhesion than the pipe mouth area; 2. Although increasing the bias voltage can enhance the bombardment effect in the deep hole area, it causes excessive sputtering of deposited metal atoms in the pipe mouth area (re-sputtering effect), and the deposition efficiency drops sharply by more than 30%; 3. Introducing a rotating fixture or auxiliary electrode to compensate for the geometric effect requires adding a multi-axis motion control module, which increases the equipment complexity and failure rate exponentially.

[0004] The industry has attempted to mitigate re-sputtering by modulating the bias waveform, but this has failed to break the paradigm of simultaneous metal atom deposition and ion bombardment. The high degree of spatial and temporal coupling between the two fundamentally limits the independent optimization of film performance and process efficiency. With the prevalence of ultra-long pipelines (>10m) in nuclear power and deep-sea engineering, this contradiction has become a core bottleneck hindering the industry's leap toward high-reliability, low-cost manufacturing. Summary of the Invention

[0005] The present invention provides a method for sputtering coating of metal pipelines based on corrosion-resistant alloy targets. The main purpose of the method is to solve the problems of coating uniformity loss, mutual exclusion between deposition efficiency and film quality, and increased complexity of dynamic compensation systems caused by geometric effects and spatiotemporal coupling in sputtering coating of metal pipelines.

[0006] To achieve the above object, the present invention provides a method for sputtering coating a metal pipeline based on a corrosion-resistant alloy target, the method comprising the following steps:

[0007] Step a: providing a magnetron sputtering device, wherein a corrosion-resistant alloy target and a metal pipe to be plated are coaxially arranged in the device, the alloy target is connected to a first pulse power supply, and the metal pipe is connected to a second pulse power supply;

[0008] Step b, setting the first pulse power supply to output a high-power pulse current to the alloy target in a first pulse sequence, wherein the first pulse sequence has an on period and an off period;

[0009] Step c, during the on-period of the first pulse sequence, sputtering the alloy target to generate neutral metal atoms, which are deposited on the surface of the metal pipe to form a film layer;

[0010] Step d, setting the second pulse power supply to output negative voltage pulses to the metal pipe in a second pulse sequence, wherein the second pulse sequence is strictly synchronized with the first pulse sequence and has an opposite phase;

[0011] In step e, during the off period of the first pulse sequence, each negative voltage pulse of the second pulse sequence is applied to the metal pipe. The negative voltage pulse accelerates the metal ions generated by sputtering in step c and still remaining in the space during the off period to bombard the surface of the film layer.

[0012] Preferably, the first pulse sequence is set to a low-frequency and high-duty-cycle mode; and the duration of each negative voltage pulse of the second pulse sequence is shorter than the duration of the off period of the first pulse sequence.

[0013] Preferably, in step e, before applying the negative voltage pulse, the method further includes the following steps: step f, applying a positive voltage detection pulse with a duration of one microsecond to two microseconds and a voltage of five volts to fifteen volts to the metal pipe; step g, measuring the peak current flowing to the metal pipe during the detection pulse and using it as the electron flow characteristic value; step h, adjusting the voltage amplitude of the negative voltage pulse to be applied immediately thereafter based on the comparison result of the electron flow characteristic value with a target electron flow characteristic value.

[0014] Preferably, the specific method of adjusting the voltage amplitude of the negative voltage pulse is: if the electron current characteristic value is higher than the target electron current characteristic value, the voltage amplitude of the negative voltage pulse is enhanced; if the electron current characteristic value is lower than the target electron current characteristic value, the voltage amplitude of the negative voltage pulse is weakened.

[0015] Preferably, the method is carried out under the condition of introducing a reaction gas, and also includes: continuously monitoring the output voltage of the first pulse power supply during the conduction period of the first pulse sequence; when the output voltage reaches a set voltage threshold related to the surface reaction state of the alloy target, triggering a high-speed solenoid valve to temporarily interrupt the supply of the reaction gas.

[0016] Preferably, the duration of temporarily interrupting the supply of the reaction gas is 100 to 500 milliseconds, and the interruption allows the surface of the alloy target to recover to a highly active metallic state.

[0017] Preferably, during the coating deposition process, a coating with gradient properties from a high-hardness bonding layer to a flexible and wear-resistant functional layer is prepared by adjusting the voltage amplitude, pulse width or pulse frequency of the second pulse power supply.

[0018] Preferably, the preparation of the gradient performance coating is specifically as follows: at the initial stage of deposition, a relatively high negative voltage pulse is applied to form a high hardness bonding layer; as the film layer grows, the voltage amplitude of the negative voltage pulse is gradually reduced or the pulse interval is increased to form a flexible and wear-resistant functional layer.

[0019] Preferably, the corrosion-resistant alloy target includes a titanium alloy target, a chromium alloy target or a zirconium alloy target.

[0020] Preferably, the frequency of the first pulse sequence is set to be between 50 Hz and 1 kHz; and the pulse repetition frequency of the negative voltage pulses of the second pulse sequence is The frequency of the first pulse train Satisfy the relationship .

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. By separating the time windows for metal atom deposition and ion bombardment densification, the neutral metal atom cloud generated by high-power sputtering can be efficiently deposited without electric field interference. The neutral metal atom cloud is then targeted with metal ions generated by the sputtering process, fundamentally avoiding the re-sputtering contradiction caused by traditional continuous bias. This mechanism transforms the coating rate and film density from being mutually constrained to being independently regulated. Engineers can freely design gradient structures from a high-bonding-strength base layer to a low-stress functional surface layer, achieving the high-speed deposition and high density that are difficult to achieve with traditional processes without additional hardware modifications.

[0023] 2. A microsecond positive voltage detection is inserted before the densification pulse to indirectly sense the real-time state of the metal ion cloud density by capturing the characteristic value of the electron saturation current. The logical comparison of this characteristic value with the preset threshold triggers the closed-loop adjustment of the subsequent negative pulse voltage, enabling the system to adaptively compensate for slow variable disturbances such as target erosion and gas fluctuations. This mechanism reuses the existing power interface and signal link, upgrading the high-performance open-loop system to an anti-interference closed-loop system, ensuring the consistency of the coating microstructure in thousands of batches, especially meeting the extreme reliability requirements in the aerospace field.

[0024] 3. In reactive sputtering, by monitoring the slight rise in voltage during the target's conduction period (a precursor to the formation of insulating compounds), a high-speed solenoid valve is triggered to instantly cut off the supply of reactive gas. This utilizes a pure argon sputtering window to remove excess compounds from the target surface, allowing the process dynamics to remain in a stable range where metals / compounds coexist. This method replaces the complex partial pressure control system with a single solenoid valve, which not only eliminates the risk of sputtering collapse caused by target poisoning, but also, in a groundbreaking move, allows operation at higher reactive gas concentrations, achieving a leap in the deposition rate of ceramic coatings such as titanium nitride compared to traditional methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the synchronization and phase relationship between the first pulse sequence and the second pulse sequence of the present invention;

[0026] Figure 2 This is a normalized numerical distribution diagram of film performance parameters at different distances of the present invention;

[0027] Figure 3 This is a timing diagram of the reaction gas control triggered by the target voltage of the present invention;

[0028] Figure 4 This is a distribution diagram of the film performance gradient along the pipeline axis of the present invention;

[0029] Figure 5 This is a diagram of the structural evolution process of the gradient performance coating of the present invention.

[0030] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0031] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] The present invention provides a method for sputtering a metal pipe coating based on a corrosion-resistant alloy target, the method comprising the following steps:

[0033] Step a: providing a magnetron sputtering device, wherein a corrosion-resistant alloy target and a metal pipe to be plated are coaxially arranged in the device, the alloy target is connected to a first pulse power supply, and the metal pipe is connected to a second pulse power supply;

[0034] Step b, setting the first pulse power supply to output a high-power pulse current to the alloy target in a first pulse sequence, wherein the first pulse sequence has an on period and an off period;

[0035] Step c, during the on-period of the first pulse sequence, sputtering the alloy target to generate neutral metal atoms, which are deposited on the surface of the metal pipe to form a film layer;

[0036] Step d, setting the second pulse power supply to output negative voltage pulses to the metal pipe in a second pulse sequence, wherein the second pulse sequence is strictly synchronized with the first pulse sequence and has an opposite phase;

[0037] In step e, during the off period of the first pulse sequence, each negative voltage pulse of the second pulse sequence is applied to the metal pipe. The negative voltage pulse accelerates the metal ions generated by sputtering in step c and still remaining in the space during the off period to bombard the surface of the film layer.

[0038] Preferably, the first pulse sequence is set to a low-frequency and high-duty-cycle mode; and the duration of each negative voltage pulse of the second pulse sequence is shorter than the duration of the off period of the first pulse sequence.

[0039] Preferably, in step e, before applying the negative voltage pulse, the method further includes the following steps: step f, applying a positive voltage detection pulse with a duration of one microsecond to two microseconds and a voltage of five volts to fifteen volts to the metal pipe; step g, measuring the peak current flowing to the metal pipe during the detection pulse and using it as the electron flow characteristic value; step h, adjusting the voltage amplitude of the negative voltage pulse to be applied immediately thereafter based on the comparison result of the electron flow characteristic value with a target electron flow characteristic value.

[0040] Preferably, the specific method of adjusting the voltage amplitude of the negative voltage pulse is: if the electron current characteristic value is higher than the target electron current characteristic value, the voltage amplitude of the negative voltage pulse is enhanced; if the electron current characteristic value is lower than the target electron current characteristic value, the voltage amplitude of the negative voltage pulse is weakened.

[0041] Preferably, the method is carried out under the condition of introducing a reaction gas, and also includes: continuously monitoring the output voltage of the first pulse power supply during the conduction period of the first pulse sequence; when the output voltage reaches a set voltage threshold related to the surface reaction state of the alloy target, triggering a high-speed solenoid valve to temporarily interrupt the supply of the reaction gas.

[0042] Preferably, the duration of temporarily interrupting the supply of the reaction gas is 100 to 500 milliseconds, and the interruption allows the surface of the alloy target to recover to a highly active metallic state.

[0043] Preferably, during the coating deposition process, a coating with gradient properties from a high-hardness bonding layer to a flexible and wear-resistant functional layer is prepared by adjusting the voltage amplitude, pulse width or pulse frequency of the second pulse power supply.

[0044] Preferably, the preparation of the gradient performance coating is specifically as follows: at the initial stage of deposition, a relatively high negative voltage pulse is applied to form a high hardness bonding layer; as the film layer grows, the voltage amplitude of the negative voltage pulse is gradually reduced or the pulse interval is increased to form a flexible and wear-resistant functional layer.

[0045] Preferably, the corrosion-resistant alloy target includes a titanium alloy target, a chromium alloy target or a zirconium alloy target.

[0046] Preferably, the frequency of the first pulse sequence is set to be between 50 Hz and 1 kHz; and the pulse repetition frequency of the negative voltage pulses of the second pulse sequence is The frequency of the first pulse train Satisfy the relationship .

[0047] Example 1: This example provides a method for sputtering coating of metal pipes based on corrosion-resistant alloy targets, aiming to solve the problems in the prior art of loss of control of coating uniformity and mutual constraints between deposition efficiency and film quality caused by geometric effects and spatiotemporal coupling; specifically, a first pulse sequence outputs a high-power pulse current to the alloy target through a first pulse power supply to form a neutral metal atom cloud, which will be deposited on the surface of the metal pipe during the conduction period to form a film layer; at the same time, a second pulse power supply outputs a negative voltage pulse to the metal pipe, which is strictly synchronized with the first pulse sequence and has an opposite phase; the negative voltage pulse will be applied during the off period of the first pulse sequence to further densify the deposited layer by accelerating the metal ions bombarding the surface of the metal pipe, thereby ensuring the coating quality; by decoupling the metal atom deposition from the ion bombardment process, the present invention effectively solves the re-sputtering contradiction caused by traditional continuous bias, realizes independent regulation of the coating rate and the film quality, and thus greatly improves the consistency and reliability of the coating.

[0048] During the specific implementation process, the first pulse sequence is set to a low-frequency, high-duty-cycle mode, which allows metal atoms to be deposited over a longer period of time, improving the density of the coating. At the same time, the duration of each negative voltage pulse in the second pulse sequence is set to be shorter than the duration of the off period of the first pulse sequence, ensuring that the negative voltage pulse bombards the deposited layer only at the appropriate time to avoid damage to the film layer. In addition, by applying a positive voltage detection pulse and measuring the characteristic value of the electron flow, changes in the electron flow can be captured in real time. The system can automatically adjust the voltage amplitude of subsequent negative voltage pulses based on the comparison result between the characteristic value and the target value, thereby ensuring the stability of the coating process and preventing the system from deviating from the preset target due to disturbances (such as gas fluctuations and target erosion). During the reactive sputtering process, by monitoring the slight change in the voltage of the target during the on-time, a high-speed solenoid valve is triggered to interrupt the supply of reactive gas. This action instantly removes excess compounds from the target surface, keeping the target surface in a highly active state, thereby ensuring the dynamic stability of the coating process. In particular, during the coating preparation process under high reactive gas concentration, it avoids the target poisoning phenomenon in traditional methods.

[0049] Example 2: This example provides a method for sputtering coating a metal pipe based on a corrosion-resistant alloy target, aiming to solve the problem of coating uniformity loss and mutual restriction between deposition efficiency and film quality caused by geometric effects and spatiotemporal coupling in the traditional sputtering coating process of metal pipes. The specific method is as follows: First, a magnetron sputtering device is used, in which the corrosion-resistant alloy target and the metal pipe to be plated are coaxially arranged, the alloy target receives a high-power pulse current through a first pulse power supply, and the metal pipe receives a negative voltage pulse through a second pulse power supply, and both are controlled by independent pulse power supplies. This setting ensures that the sputtering process between the target and the pipe and the ion bombardment are carried out synchronously, avoiding the problem of inconsistent coating quality caused by insufficient voltage control in traditional methods. Then, the first pulse power supply outputs a high-power pulse current, the pulse frequency is set in the range of 50 Hz to 1000 Hz, and the pulse duty cycle is set to 60% to 80%. During the conduction period of the pulse sequence, the neutral metal atoms generated by the sputtering alloy target are deposited on the surface of the metal pipe to form a uniform film layer. The high-power output period of the first pulse sequence accelerates the metal atom deposition rate, thereby effectively improving the deposition efficiency of the coating.

[0050] On this basis, the second pulse power supply outputs a negative voltage pulse, and the pulse frequency is the same as that of the first pulse sequence, but the output negative voltage pulse is opposite to the phase of the first pulse sequence, ensuring that the negative voltage pulse is only applied during the off period of the first pulse sequence, and the duration of each negative voltage pulse is less than the off period of the first pulse sequence, and the amplitude is adjustable. The purpose of this step is to use the metal ions generated by the sputtering of the first pulse sequence and remaining in the space to further densify the deposited layer through the accelerated bombardment of the negative voltage pulse, thereby optimizing the bonding strength and hardness of the film layer; at the same time, in order to ensure the stability of the coating process, a positive voltage detection pulse step is added. In the first pulse Before the sequence shutdown period, the second pulse power supply applies a positive voltage detection pulse with a duration of 1 microsecond to 2 microseconds and a voltage of 5 volts to 15 volts to the metal pipe. This pulse can detect the electron flow generated on the surface of the metal pipe and measure the characteristic value of the electron flow. The measured characteristic value of the electron flow is compared with the target characteristic value of the electron flow to adjust the voltage amplitude of the negative voltage pulse. If the measured characteristic value of the electron flow is higher than the target value, the system enhances the voltage amplitude of the negative voltage pulse. If it is lower than the target value, the voltage amplitude is weakened. This closed-loop feedback mechanism can automatically compensate for disturbances caused by factors such as target material erosion and gas fluctuations to ensure the consistency and reliability of the coating process.

[0051] During the sputtering process, when it is monitored that the voltage of the target material rises during the conduction period (i.e., a precursor to the formation of insulating compounds), the system cuts off the supply of reactive gas through a high-speed solenoid valve to remove excess compounds on the target surface and keep the target surface in a highly active metallic state, thereby ensuring the stability of the coating process. This method can avoid the risk of sputtering collapse caused by target poisoning in traditional sputtering processes and increase the coating deposition rate under high-concentration reactive gas. During the coating deposition process, by gradually adjusting parameters such as the voltage amplitude, pulse width or pulse frequency of the second pulse power supply, this embodiment can prepare a gradient coating having a high-hardness bonding layer to a flexible and wear-resistant functional layer. Specifically, at the initial stage of deposition, a higher negative voltage pulse is applied to form a bonding layer with higher hardness. As the film layer grows, the voltage amplitude of the negative voltage pulse is gradually reduced or the pulse interval is increased, and finally a flexible and wear-resistant functional layer is formed. Through this method, the coating can achieve a balance between high bonding strength and high wear resistance in terms of performance. Through the above process, this embodiment successfully achieves independent regulation of efficient deposition and high density of metal pipeline coating, avoids the re-sputtering contradiction in traditional continuous bias sputtering technology, and greatly improves the consistency, reliability and film quality of the coating.

[0052] Example 3: In harsh application environments such as petrochemicals, nuclear energy, and deep-sea operations, the inner walls of aspect ratio metal pipes face severe challenges of corrosion and wear for a long time, which directly affects their service life and operational safety. Existing magnetron sputtering technology has common technical limitations when applied to such complex structures: On the one hand, due to the attenuation of the electric field in the deep hole area of ​​the pipe, the ion bombardment energy is insufficient, making it difficult for the bonding strength and density of the deposited film layer to meet expectations. In particular, the re-sputtering effect is prone to occur in the pipe mouth area, that is, the deposited metal atoms are over-bombarded by high-energy ions and peel off, thereby significantly reducing the deposition efficiency. On the other hand, traditional technologies generally adopt a continuous bias mode, which causes the neutral metal atom deposition and ion bombardment densification processes to be highly coupled in time and space dimensions, essentially limiting the strategic space for independent and precise control of the coating rate and film quality. To address the above challenges, the present invention proposes a metal pipeline sputtering coating method based on corrosion-resistant alloy targets. This method decouples the metal atom deposition and ion bombardment steps in time sequence and introduces a closed-loop feedback mechanism to achieve independent optimization of the coating rate and film quality, and significantly improve the uniformity and reliability of the coating performance.

[0053] This experiment uses a set of magnetron sputtering equipment customized for this method, which mainly consists of: a sputtering chamber with an inner diameter of meters, height The vertical cylindrical vacuum chamber is equipped with a high-performance vacuum pumping system, which can achieve a vacuum below The ultimate vacuum degree of Pa; the corrosion-resistant alloy target and the first pulse power supply are coaxially set at the center of the cavity with a length of meters, diameter The cylindrical titanium alloy target material has a purity of , the target is connected to a set of rated output power up to A kilowatt high-power pulsed DC power supply, namely the first pulse power supply, the metal pipe to be plated and the second pulse power supply, the metal pipe to be plated, as a test piece, its material is Q235 carbon steel, and it has been pre-treated by precise mechanical polishing and ultrasonic cleaning. The pipe is coaxially fixed to the outside of the target and connected to a set of programmable pulse bias power supply, namely the second pulse power supply, whose maximum negative voltage output capacity is The reaction gas supply system is integrated with a high-precision mass flow controller, which can accurately control the flow of argon gas used for sputtering and nitrogen gas used for reaction. The in-situ monitoring system includes a vacuum pressure gauge integrated in the chamber, a sensor for real-time acquisition of target current and voltage signals, and a plasma local density detection unit designed based on the Langmuir probe principle, which is used to monitor key process parameters in real time. In actual engineering implementation, the first pulse sequence (target power supply) is set as: frequency ( )for Hertz, the technical consideration for selecting this frequency is to ensure that the plasma can respond quickly and maintain a stable state while ensuring the target sputtering efficiency. Generally, a lower pulse frequency may cause fluctuations in plasma stability, while a too high frequency may introduce additional power loss and cause system resonance. The duty cycle is set to The design of high duty cycle is to maximize the sputtering efficiency and deposition rate of neutral metal atoms, ensuring that sufficient metal atoms are deposited on the surface of the metal pipe to be plated during the peak power output of the target, thereby improving the overall coating efficiency. Practice has shown that too low a duty cycle will significantly reduce the deposition rate and affect production efficiency; on the contrary, if the duty cycle is too high, it may compress the effective duration of the shutdown period, thereby limiting the efficiency of subsequent ion bombardment and may cause excessive instantaneous heat load on the target. The average power is set to The power level is 100 kilowatts. This power level is determined based on engineering optimization results to avoid target overheating and equipment overload while ensuring stable sputtering of the target and obtaining a sufficient deposition rate. The second pulse sequence (metal pipeline bias power supply) is set as follows: the negative voltage pulse is set to be strictly synchronized with the first pulse sequence and has opposite phases. This synchronization strategy ensures that the negative voltage pulse is only applied during the off-period of the first pulse sequence (i.e., the target power output is at its lowest point). The fundamental technical consideration of this timing decoupling scheme is that during the on-period of the first pulse sequence, neutral metal atoms can be efficiently deposited without being affected by high-energy ion bombardment, thereby fundamentally avoiding the re-sputtering effect caused by traditional continuous bias and ensuring that the neutral metal atom cloud is efficiently deposited without electric field interference. During the off-period of the first pulse sequence, the metal ions generated by sputtering and still remaining in the space are accelerated by the negative voltage pulse to bombard the surface of the deposited film layer to achieve film densification. This separation mechanism allows the coating rate and film density to be independently controlled. The duration of the negative voltage pulse is set to microseconds, which is shorter than the off period of the first pulse train. Hertz frequency, Under the duty cycle setting, the off period lasts The technical consideration for selecting this duration is to ensure that during the off period, the negative voltage pulse can effectively accelerate the metal ion bombardment of the deposited layer, while avoiding excessive plasma attenuation or unnecessary energy loss caused by a long pulse duration, thereby optimizing the ion bombardment efficiency. At the same time, historical data shows that if the duration is too long, the target material may still have a bias effect before the end of the off period, thereby affecting the start of the next deposition cycle; if the duration is too short, it may lead to insufficient bombardment energy and poor film densification effect. The initial setting range of the negative voltage pulse voltage amplitude control range is Fuzhi The determination of this range is based on the consideration of engineering optimization of film bonding strength and densification effect, and is dynamically adjusted through a closed-loop feedback mechanism during the coating process. In practice, too high a negative bias voltage may cause excessive sputtering of the deposited film, thereby reducing the deposition efficiency; while too low a bias voltage cannot effectively bombard the film layer, affecting its density. The pulse repetition frequency of the negative voltage pulse ( ) and the frequency of the first pulse sequence Set to be equal, that is, satisfy the relationship This setting ensures that a negative voltage pulse is applied during each off period of the first pulse sequence, thereby ensuring that the bombardment process of the deposited layer is continuous and uniform. The reaction gas atmosphere is: the working pressure is set to Pa, this pressure is the optimal choice for both deposition rate and film density under the premise of ensuring stable plasma excitation and moderate ion mean free path (to facilitate ion bombardment), and the argon flow rate is kept stable and controlled at The nitrogen flow rate is set to 100 standard cubic centimeters per minute (sccm) based on the stoichiometric ratio of the target titanium nitride (TiN) coating and the consideration of avoiding target poisoning. The standard cubic centimeter per minute is dynamically adjusted during the coating deposition process through a closed-loop feedback mechanism. The technical considerations for introducing this adjustment mechanism are to avoid the formation of an insulating compound layer on the target surface due to excessive reactive gas flow (the so-called target poisoning phenomenon), which leads to a sharp drop in sputtering efficiency or even complete failure; at the same time, to ensure that there is a sufficient concentration of reactive gas to fully react with the sputtered metal atoms to form the desired target compound coating.

[0054] In this test, the pre-treated Q235 carbon steel pipe sample was precisely fixed in the sputtering chamber, and then the chamber was evacuated to Pa, after the vacuum degree is stable, Standard cubic centimeters per minute of argon, and the working pressure is precisely stabilized at Pa, then start the first pulse power supply to Hertz frequency, The duty cycle and The average power of 1000 kilowatts is used to apply high-power pulse current to the titanium alloy target, thereby establishing a stable argon plasma in the cavity and efficiently sputtering to produce neutral titanium atoms. During the on-period of the first pulse sequence, the generated neutral titanium atoms are efficiently deposited on the inner wall surface of the metal pipe to be plated to form an initial film layer. During this process, the second pulse power supply is strictly synchronized with the first pulse sequence and controlled in opposite phases to ensure that a continuous pulse current is applied to the metal pipe during each off-period of the first pulse sequence. The negative voltage pulse of microseconds uses the metal ions generated during the sputtering process and still remaining in the space to accelerate and bombard the metal ions to the surface of the deposited film layer, thereby achieving the densification of the film layer. The initial amplitude of the negative voltage pulse is set to volts, continue the sputtering process minutes to ensure that a titanium coating with a target thickness is formed on the inner wall of the pipe to be plated. After the sputtering process is completed, the length-diameter pipe is evenly cut into five sections along its axial direction. to cm), the upper middle section of the tube ( to cm), middle section of tube ( to cm), the lower middle section of the tube ( to cm) and the bottom of the tube ( to The film thickness, surface morphology and density of the samples were observed and analyzed using a scanning electron microscope (SEM), and microhardness tests were performed simultaneously.

[0055] In another set of experiments, to verify the role of the closed-loop feedback mechanism in regulating the ion bombardment intensity, the system first established and maintained a stable sputtering environment based on the above initial operation. During each off period of the first pulse sequence (i.e., before the negative voltage pulse was applied), the second pulse power supply applied a pulse to the metal pipe for a duration of microseconds, voltage is The function of the detection pulse is to indirectly and in real time sense the density state of the metal ion cloud in the current plasma by collecting the electron saturation current flowing to the surface of the pipe sample. The peak current flowing to the metal pipe during the detection pulse is used as the electron flow characteristic value. Based on the experience gained from the previous experiments, a target electron flow characteristic value is set. for mA, the target value corresponds to the empirical optimization result of the plasma ion density required to achieve the best film densification. Based on the comparison between the electron current characteristic value measured in real time and the target electron current characteristic value, the system automatically adjusts the voltage amplitude of the negative voltage pulse to be applied immediately afterwards through the PID controller integrated in the second pulse power supply. If Higher than , the system enhances the voltage amplitude of the negative voltage pulse, and the adjustment step size can be set according to the actual situation, for example, The deviation of mA can be increased accordingly The amplitude of volts is used to compensate for the insufficient bombardment effect caused by the possible high ion density. On the contrary, if Lower than , the system weakens the voltage amplitude of the negative voltage pulse, for example, The deviation of milliamperes can be reduced accordingly The amplitude of volts is used to avoid excessive bombardment intensity or reduced efficiency due to insufficient ion density. The fundamental consideration of this adjustment procedure is that in the dynamic sputtering process, slow-changing disturbance factors such as the erosion degree of the target material, the local plasma distribution and the fluctuation of the cavity background gas may cause real-time changes in the metal ion density in the plasma. The traditional open-loop system cannot effectively compensate for such changes. By introducing the characteristic value of the electron flow as a feedback signal and adjusting the ion bombardment intensity (i.e., the negative voltage pulse amplitude) in real time according to its deviation from the preset target, this system has acquired adaptive capabilities, which can ensure that the bombardment effect on the deposited film layer remains highly consistent throughout the coating cycle, thereby significantly improving the microstructural uniformity and macroscopic performance reliability of the prepared coating. In the entire coating deposition process, first of all, in the initial Within minutes, the system applies a relatively high negative voltage pulse, the amplitude of which is adjusted in real time according to the closed-loop feedback mechanism mentioned above, and the initial setting can reach about volts to promote the formation of a high hardness bonding layer, and then in the next Within minutes, the system gradually reduces the voltage amplitude of the negative voltage pulse, for example, every Minutes reduced by about volts, and at the same time increase the pulse interval appropriately, for example, Minute increase The microsecond pulse interval is ultimately aimed at forming a flexible and wear-resistant functional layer. The preparation of this gradient performance coating achieves an optimized balance between the interface bonding strength and surface wear resistance of the coating by constructing a multi-layer structure. The high-hardness bonding layer can effectively resist substrate deformation and external impact, providing excellent adhesion; while the flexible and wear-resistant functional layer can effectively disperse stress, improve fatigue resistance and wear resistance, thereby meeting the complex requirements of the comprehensive mechanical properties of the coating in specific application scenarios. After the sputtering process, the film layers taken from different areas are subjected to microhardness tests, the bonding strength test is carried out using the scratch method, the film density is evaluated using electrochemical impedance spectroscopy (ECL), and a salt spray test is carried out to evaluate its corrosion resistance.

[0056] In order to verify the target material poisoning suppression and process stability of the present invention in reactive sputtering, nitrogen was introduced stably on the basis of the above sputtering process, and the initial flow rate was set to Standard cubic centimeters per minute, thereby performing titanium nitride (TiN) reactive sputtering, continuously monitoring the output voltage of the first pulse power supply during the first pulse sequence conduction period, when the output voltage is monitored to have a small and lasting about milliseconds of upward movement, such as from its stable value Bend upward to Volts. The setting of this voltage threshold is based on the early exploratory tests. As a clear precursor to the formation of an insulating compound layer on the target surface and changes in sputtering characteristics, the system immediately triggers a high-speed solenoid valve after receiving this signal, instantly interrupting the supply of nitrogen. The selection of this voltage threshold, its fundamental technical consideration is to accurately identify the initial stage of the transformation of the target surface from the main metal state to the main reaction compound state. If the trigger is too early, it may cause unnecessary interruption of the reaction gas, thereby affecting the stoichiometric ratio and quality of the target compound coating; if the trigger is too late, it may cause a stable insulating layer to form on the target surface, causing the collapse of the sputtering process. By dynamically monitoring the target voltage and setting a precise trigger threshold, real-time perception and precise control of the reaction state of the target surface are achieved; the duration of the nitrogen supply interruption is set to milliseconds. During this period, sputtering is carried out by introducing only argon gas to form a plasma, which can effectively remove the excess insulating compound layer on the target surface and restore the target surface to a highly active metal state. After the interruption duration ends, the high-speed solenoid valve automatically resumes the nitrogen supply. The setting of the interruption duration must ensure that the target surface compounds are effectively removed to restore the sputtering activity, and minimize the impact on the overall deposition rate and coating stoichiometric ratio. If the duration is too short, the compounds may not be completely removed, resulting in low subsequent sputtering efficiency. If it is too long, the pure metal deposition time will be extended, thereby changing the final stoichiometric ratio of the target compound coating and affecting the coating performance. After the sputtering process is completed, the chemical composition of the prepared TiN coating is analyzed by energy dispersive X-ray spectrometer (EDS) or X-ray photoelectron spectroscopy (XPS), microhardness test, adhesion test and corrosion resistance test.

[0057] Table 1: Test results of coating performance in different pipeline areas.

[0058]

[0059] The results of scanning electron microscopy show that under the time-decoupled sputtering mode of the present invention, a dense and uniform titanium metal film layer is formed on the inner wall of the entire aspect ratio metal pipe. The thickness of the film layer shows a slight and gradually thinning trend from the pipe mouth to the pipe bottom, but its overall fluctuation range can be controlled within about Compared with the traditional continuous bias sputtering mode, the film thickness in the deep hole area may decrease by more than In the long During the coating deposition process of 10 minutes, the characteristic value of electron current recorded by the in-situ monitoring system is always within mA to At the same time, it is observed that the amplitude of the negative voltage pulse can fluctuate between Fuzhi The system can make dynamic adjustments within a range of volts. The effective operation of this closed-loop feedback mechanism enables the system to effectively compensate for slow-variable disturbances such as target erosion, local plasma distribution changes, and cavity background gas fluctuations, thereby ensuring the relative stability of the ion density in the plasma and continuously maintaining the effect of optimizing the bombardment of the deposited layer. The microhardness of the high-hardness bonding layer (in the initial stage of deposition) reaches about Vickers hardness, its bonding strength scratch critical load is about This result shows that the layer has excellent adhesion and initial impact resistance, and the microhardness of the flexible and wear-resistant functional layer (later deposition stage) is about Vickers hardness, its bonding strength scratch critical load is about Compared with the bonding layer, the hardness of this layer is slightly lower, but the toughness is significantly enhanced. A longer plastic deformation zone was observed in the scratch test, indicating that it has better wear resistance. The experimental data of this stage clearly revealed that by precisely controlling the voltage amplitude, pulse width or pulse frequency of the second pulse power supply, the present invention can successfully prepare a gradient performance coating from a high-hardness bonding layer to a flexible and wear-resistant functional layer. This layered structure can give full play to the performance advantages of materials at different levels, effectively improve the comprehensive mechanical properties and service reliability of the coating, and at the same time, the introduction of a closed-loop feedback mechanism significantly improves the uniformity of the coating performance, which can meet application scenarios with extremely high requirements for coating reliability.

[0060] Table 2: Comparison of TiN coating performance between the method of the present invention and the traditional continuous mode.

[0061]

[0062] During titanium nitride (TiN) reactive sputtering, in the traditional continuous sputtering mode, as the nitrogen flow rate continues to increase, the target voltage gradually increases. When it reaches a certain critical point, the target voltage suddenly jumps, which is a sign of obvious poisoning on the target surface, resulting in a sharp drop in the deposition rate. In contrast, the method of the present invention effectively suppresses the occurrence of target poisoning by monitoring the target voltage in real time and promptly triggering a high-speed solenoid valve to instantaneously interrupt the nitrogen supply. The analysis results of energy dispersive X-ray spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS) show that the TiN coating prepared by the method of the present invention has a Ti:N stoichiometric ratio that is closer to the ideal , indicating that the film composition is more accurate, and at the same time, the film density is significantly improved, and the average microhardness is increased by about The average bonding strength increased by about The salt spray test results further show that under the same test time, the corrosion depth of the TiN coating prepared by the method of the present invention is significantly smaller than that of the coating prepared by the traditional method, and the corrosion resistance is improved by about Under the premise of ensuring the high quality of the prepared coating, the average deposition rate of the method of the present invention reaches microns per hour, compared to the traditional method micrometers per hour, the deposition efficiency increased by about This significant improvement is mainly due to the fact that the target surface can be continuously maintained in a highly active metal state, effectively avoiding the reduction in sputtering efficiency due to target poisoning. The experimental results of this stage strongly confirm that the present invention can avoid the potential risk of target poisoning in reactive sputtering by dynamically monitoring the target voltage and intelligently controlling the reaction gas flow rate. This method breakthrough allows operation at higher reaction gas concentrations, thereby achieving significant improvements in the deposition rate and film quality of the compound coating.

[0063] Example 4: This example combines Figures 1 to 5 , a metal pipeline sputtering coating method based on corrosion-resistant alloy target is described. Figure 1 As shown, in the first pulse (target material) part, it periodically includes two stages: the on-period and the off-period. The on-period is used to apply high-power pulse current to the corrosion-resistant alloy target to achieve sputtering deposition of metal atoms, while the off-period is to empty the ion bombardment window. Correspondingly, in the second pulse (pipeline) part, a detection pulse and a negative pulse are inserted in each off-period. The detection pulse refers to a positive voltage detection signal with a duration of one microsecond to two microseconds and a voltage of five volts to fifteen volts applied to the metal pipeline to measure the characteristic value of the electron flow; the negative pulse is a negative voltage pulse applied to the metal pipeline, which is used to accelerate the bombardment of metal ions to densify the deposited layer and form a closed-loop control. At the process level, the on-period corresponds to the atomic deposition stage, in which neutral metal atoms are efficiently deposited on the pipeline surface; and the off-period corresponds to the ion bombardment stage, which is used to enhance the density of the film layer.

[0064] like Figure 2 As shown in the figure, the vertical axis is the normalized value, and the horizontal axis is the distance from the pipe mouth, which is marked as 5cm, 30cm, 60cm, 90cm and 115cm respectively; there are four performance indicators marked in the curve graph, namely the film thickness represented by the hollow circle symbol, the roughness represented by the hollow triangle symbol, the hardness represented by the hollow square symbol and the binding force represented by the asterisk symbol. Among them, the film thickness curve is represented by the hollow circle symbol and the solid line, reflecting that the fluctuation range of the film thickness at different pipe sections is small, and the overall change is within ±10%; the roughness is represented by the hollow triangle symbol and the dotted line, showing that the difference in roughness at different positions is very small; the hardness is represented by the hollow square symbol and the short dash line, and the data of each measuring point remains basically stable; the binding force is represented by the asterisk symbol and the dotted line, which fluctuates slightly but the overall characteristics are maintained at a high level.

[0065] like Figure 3 As shown, first, when the target voltage is in a normal state, the system is in a stable operating state. When the voltage shows a slight upward trend, it is identified as a precursor to the formation of insulating compounds. The system determines that the voltage has reached a preset threshold and immediately triggers a high-speed solenoid valve, switching the reactive gas supply from a stable supply to a temporary interruption. During this interruption, the reactive atmosphere enters the pure argon sputtering window, which lasts for 100 to 500 milliseconds. The purpose is to use pure argon plasma to remove excess compounds from the target surface and restore the target surface state from the excess compound state to a highly active metallic state, thereby achieving the goal of maintaining a stable highly active metallic state. Once the removal is complete, the system resumes normal supply, the target surface state also returns to the highly active metallic state, and the voltage returns to stable operation.

[0066] like Figure 4 As shown in the figure, the distribution of membrane performance parameters along the pipeline axis after the method of the present invention is adopted. Through the time-series decoupling control, the uniformity of various performance indicators is significantly improved, and the fluctuation range is controlled within ±10%, which is far superior to the traditional continuous bias method. Figure 5 As shown in the figure, the gradient structure evolution achieved by dynamically adjusting the negative voltage pulse parameters during the coating deposition process is demonstrated. A high-hardness bonding layer (350HV) is initially formed, and then gradually transitions to a flexible and wear-resistant functional layer (280HV) in the later stage, achieving an optimized combination of performance.

[0067] Example 5: During the sputtering coating process of metal pipes, in order to achieve decoupling of metal atom deposition and ion bombardment operations in the time dimension, the first pulse power supply and the second pulse power supply are respectively connected to a timing scheduling system with synchronous control capability. The system generates a unified reference signal through a shared clock source, and performs periodic control on the two pulse sequences under program settings, so that the starting time point of the second pulse sequence strictly corresponds to the beginning of the off period of the first pulse sequence, avoiding electric field interference caused by power fluctuations or phase overlap. The synchronization logic in the timing scheduling system has a fixed delay correction function, which can automatically adjust and lock the phase difference during the system initialization phase to ensure that the two pulse sequences maintain a stable anti-phase state throughout the entire cycle; the second pulse power supply has an internal integrated positive voltage detection pulse. The positive voltage detection pulse is applied to the surface of the metal pipe by an independent output channel to collect the current response signal in the electron saturation range. The signal forms a peak value during the detection pulse period, and the peak value is used as the electron flow characteristic for subsequent control judgment. The signal acquisition path adopts a current sampling branch isolated from the high-voltage bias circuit. The output is amplified and filtered and sent to the control unit. Before the negative voltage pulse is applied, the control unit calculates the deviation between the current electron flow characteristic value and the preset target value, and sets the voltage amplitude of the next negative voltage pulse accordingly. The deviation calculation logic introduces limiting parameters, including the upper limit of the adjustment amplitude and the adjustment step size, to ensure that the control process converges gradually within the allowable range and avoids sudden changes or fluctuations causing film interference.

[0068] During the film deposition process, the amplitude of the negative voltage pulse is maintained at a preset high level in the initial stage to enhance the accelerated bombardment of metal ions. This setting is maintained for about ten minutes to form a dense bottom layer with high bonding strength. As the deposition time increases, the system adjusts the voltage amplitude and pulse interval in a linked manner at fixed time intervals, causing it to gradually change toward low amplitude and large intervals. This adjustment path is based on the response characteristics of stress conduction and structural evolution during film growth, aiming to enhance the flexibility and wear resistance of the upper film layer while retaining the adhesion of the bottom layer, thereby forming a structural transition with gradient performance. The target setting of the electron flow characteristic value is based on the plasma excitation intensity and target sputtering efficiency of the system, and is generally located near the median of the measured saturation current. The adjustment process is only based on the current deviation and the preset control algorithm. No external samples or experimental data are involved. The feedback threshold and step size in the control strategy are set according to the general electron beam control principle in this field. The specific values ​​can be automatically estimated according to the target material type and cavity parameters during the system initialization phase or manually input by the operator. The system setting logic remains open to facilitate adaptation to different working conditions. The output circuit of the detection pulse has fast switching capability, and its voltage output range can be adjusted between five volts and fifteen volts. The pulse width is set between one microsecond and two microseconds. The current sampling circuit uses a sampling front end with a bandwidth of not less than one hundred megahertz, and is equipped with an analog preamplifier and anti-interference filtering module to ensure the complete acquisition and stable interpretation of the detection signal. After signal processing, the control module will execute the negative voltage pulse amplitude increase and decrease commands based on the logical judgment results. This process is completed by the main control unit in a closed loop within each pulse cycle.

[0069] In plasma state monitoring, the Langmuir probe installed inside the cavity is arranged in the neutral zone between the target material and the workpiece to be plated, the front end of the probe is placed on the center plane of the cavity, the incident angle is maintained at forty-five degrees, and the probe area is controlled within five square millimeters. The collected current signal is combined with the detection pulse data to evaluate the current trend of ion cloud density changes. As an auxiliary input for the system adjustment strategy, the probe signal and the power control signal are logically interconnected through optoelectronic isolation to avoid high-voltage interference affecting the judgment process. For the test of film performance, the microhardness measurement uses the standard Vickers hardness method with a loading load of one hundred grams and a holding time of ten seconds. The bonding strength test uses the cone scratch method, which gradually loads until the film layer undergoes initial cracking and complete desorption, and records the corresponding load as a judgment indicator. The surface morphology and thickness of the film layer are observed using scanning electron microscope cross-sectional images. The corrosion performance is evaluated based on the results of the neutral salt spray test, and the evaluation indicator is the change in corrosion pit depth per unit time.

[0070] Example 6: In a specific application implementation, the present invention is used to apply a biocompatible wear-resistant coating to human implants made of titanium alloy to address the technical challenges brought about by the complex curved surfaces of the implants and the strict batch-to-batch consistency requirements. Before coating the batch of implants, a systematic offline calibration procedure is first performed to provide deterministic target parameters and control models for the subsequent closed-loop control algorithm. Specifically, the procedure uses standard test samples. The first step is to accurately calibrate the target electron flow characteristic value corresponding to the optimal film densification effect. This step is achieved by gradually increasing the flow rate of the reaction gas at a preset fixed step size within the preset process parameter range, and simultaneously using the in-situ monitoring system to collect the stable output voltage of the first pulse power supply during the conduction period under different flow rates, and the electron flow characteristic value measured by the second pulse power supply during the application of the positive voltage detection pulse. Through this process, a response curve of the target voltage and the reaction gas flow rate is drawn, and the voltage mutation area where the target material is about to enter the poisoning state is identified. The point on the curve where the first-order derivative value exceeds a preset judgment value for the first time is accurately set as the voltage threshold to trigger the high-speed solenoid valve in the subsequent process. At the same time, the film layer sample generated at each flow point is subjected to nanoindentation testing to obtain its microhardness value. Finally, the microhardness value is associated with the corresponding electron flow characteristic value to draw a hardness-electron flow correlation curve. Target electron flow characteristic value The characteristic value of the electron flow corresponding to the hardness peak or the beginning of the hardness entering the stable platform region in this relationship curve is thus deterministically set, thereby directly linking the control target with the quantifiable optimal material performance.

[0071] On this basis, the second step of the procedure is to establish a transfer function between the ion bombardment intensity and the key performance of the film layer, in order to generate a precise control strategy for the gradient coating. By changing only the amplitude of the negative voltage pulse applied to the sample at a constant target electron current characteristic value, a series of single-layer films with different bombardment intensities are prepared, and the bonding force of each film layer is scratch tested. Thus, a function model describing the relationship between the bonding force and the negative voltage pulse amplitude can be obtained. In response to the application requirements of this human implant, the coating design requires the highest bonding force at the interface close to the substrate, and the surface layer must have the best wear resistance. This wear resistance has been associated with the microhardness in the first step. Based on this design goal, the system automatically generates a sequence of negative voltage pulse amplitudes from high to low that varies with deposition time. , ensuring that during the growth process of the film layer, its properties can accurately and smoothly transition from high bonding strength to high hardness.

[0072] Furthermore, when sputter coating an actual implant workpiece, the parameters determined by the aforementioned calibration procedure serve as the core input to drive the operation of the entire closed-loop control system. During each off period of the first pulse sequence, the system measures the characteristic value of the instantaneous electron current , and calculate its characteristic value with the target electron current Deviation This deviation signal is then fed into the proportional-integral controller integrated in the second pulse power supply. The iterative algorithm for the amplitude of the next negative voltage pulse Make real-time adjustments. Among them, the proportional gain of the controller With integral gain The value is automatically adjusted during the offline calibration phase by applying a step response to the system and analyzing it. It aims to ensure that the control loop has the characteristics of fast response and high stability, and can effectively compensate for local fluctuations in plasma density caused by workpiece rotation and complex curved surfaces.

[0073] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for sputtering coating of metal pipelines based on corrosion-resistant alloy targets, characterized in that: The method comprises the following steps: Step a: providing a magnetron sputtering device, wherein a corrosion-resistant alloy target and a metal pipe to be plated are coaxially arranged in the device, the alloy target is connected to a first pulse power supply, and the metal pipe is connected to a second pulse power supply; Step b, setting the first pulse power supply to output a high-power pulse current to the alloy target in a first pulse sequence, wherein the first pulse sequence has an on period and an off period; Step c, during the on-period of the first pulse sequence, sputtering the alloy target to generate neutral metal atoms, which are deposited on the surface of the metal pipe to form a film layer; Step d, setting the second pulse power supply to output negative voltage pulses to the metal pipe in a second pulse sequence, wherein the second pulse sequence is strictly synchronized with the first pulse sequence and has an opposite phase; In step e, during the off period of the first pulse sequence, each negative voltage pulse of the second pulse sequence is applied to the metal pipe. The negative voltage pulse accelerates the metal ions generated by sputtering in step c and still remaining in the space during the off period to bombard the surface of the film layer.

2. The method for sputtering coating a metal pipeline based on a corrosion-resistant alloy target according to claim 1, characterized in that: The first pulse sequence is set to a low-frequency and high-duty-cycle mode; the duration of each negative voltage pulse of the second pulse sequence is shorter than the duration of the off period of the first pulse sequence.

3. The method for sputtering coating a metal pipeline based on a corrosion-resistant alloy target according to claim 1, characterized in that: In step e, before applying the negative voltage pulse, the method also includes the following steps: step f, applying a positive voltage detection pulse with a duration of one microsecond to two microseconds and a voltage of five volts to fifteen volts to the metal pipe; step g, measuring the peak current flowing to the metal pipe during the detection pulse and using it as the electron flow characteristic value; step h, adjusting the voltage amplitude of the negative voltage pulse to be applied immediately thereafter based on the comparison result of the electron flow characteristic value with a target electron flow characteristic value.

4. The method for sputtering coating a metal pipeline based on a corrosion-resistant alloy target according to claim 3, characterized in that: The specific method of adjusting the voltage amplitude of the negative voltage pulse is: if the electron current characteristic value is higher than the target electron current characteristic value, the voltage amplitude of the negative voltage pulse is increased; if the electron current characteristic value is lower than the target electron current characteristic value, the voltage amplitude of the negative voltage pulse is decreased.

5. The method for sputtering coating a metal pipeline based on a corrosion-resistant alloy target according to claim 1, characterized in that: The method is carried out under the condition of introducing a reaction gas, and also includes: continuously monitoring the output voltage of the first pulse power supply during the conduction period of the first pulse sequence; when the output voltage reaches a set voltage threshold related to the surface reaction state of the alloy target material, triggering a high-speed solenoid valve to temporarily interrupt the supply of the reaction gas.

6. The method for sputtering coating a metal pipeline based on a corrosion-resistant alloy target according to claim 5, characterized in that: The duration of temporarily interrupting the supply of the reaction gas is 100 to 500 milliseconds, and the interruption allows the surface of the alloy target to recover to a highly active metallic state.

7. The method for sputtering coating a metal pipeline based on a corrosion-resistant alloy target according to claim 1, characterized in that: During the coating deposition process, a coating with gradient properties from a high-hardness bonding layer to a flexible and wear-resistant functional layer is prepared by adjusting the voltage amplitude, pulse width or pulse frequency of the second pulse power supply.

8. The method for sputtering coating a metal pipeline based on a corrosion-resistant alloy target according to claim 7, characterized in that: The preparation of the gradient performance coating is specifically as follows: at the initial stage of deposition, a relatively high negative voltage pulse is applied to form a high-hardness bonding layer; as the film layer grows, the voltage amplitude of the negative voltage pulse is gradually reduced or the pulse interval is increased to form a flexible and wear-resistant functional layer.

9. The method for sputtering coating a metal pipeline based on a corrosion-resistant alloy target according to claim 1, characterized in that: The corrosion-resistant alloy target includes a titanium alloy target, a chromium alloy target or a zirconium alloy target.

10. The method for sputtering coating a metal pipeline based on a corrosion-resistant alloy target according to claim 1, characterized in that: The frequency of the first pulse sequence is set to be between 50 Hz and 1 kHz; and the pulse repetition frequency of the negative voltage pulse of the second pulse sequence is set to be between 50 Hz and 1 kHz; The frequency of the first pulse train Satisfy the relationship .

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