A vapor deposition process for strengthening valve sealing surfaces

Abstract

This invention relates to the field of metal surface strengthening technology and discloses a vapor deposition process for strengthening valve sealing surfaces, comprising: heating a valve substrate in a vacuum chamber; introducing a precursor gas to construct a vapor deposition environment; monitoring pressure fluctuation signals in the near-wall region of the sealing surface to determine the transient pressure drop rate; comparing the transient pressure drop rate with a pressure transition threshold to determine the vapor phase depletion stage and identify a low-collision-section region; applying a radio frequency negative bias voltage to the valve substrate during the vapor phase depletion stage to accelerate ions through the low-collision-section region, with ions impacting the crystal nuclei of the sealing surface with peak kinetic energy, inducing crystal dislocations. This invention utilizes the ballistic penetration mechanism of the vapor phase depletion interface to prevent ions from scattering in the vapor phase and achieve deep energy injection, suppressing the longitudinal growth of columnar crystals, forming an equiaxed crystal structure, and enhancing the density of the strengthening layer and the interfacial bonding force.

Description

Technical Field

[0001] This invention belongs to the field of metal surface strengthening technology, and particularly relates to a vapor deposition process for strengthening valve sealing surfaces. Background Technology

[0002] Current vapor deposition processes used for strengthening valve sealing surfaces employ vacuum reaction chambers, utilizing the active groups of precursor gases to nucleate and grow on the substrate surface, thereby constructing a hard reinforcing layer. The crystallization process of gaseous substances on the solid surface is constrained by the principle of minimum energy. Precursor molecules undergo anisotropic epitaxial growth under constant thermodynamic driving force, resulting in a columnar crystal arrangement perpendicular to the interface in the microstructure of the deposited layer. Under heavy-load opening and closing conditions, valves generate tangential shear stress, which concentrates in the columnar grain boundary region, inducing microcracks to extend along the grain boundaries to the interface depth. With the erosion of the fluid medium, the reinforcing layer peels off, leading to early failure of the sealing pair. To refine the grains, conventional methods limit growth kinetics by lowering the reaction temperature. This method results in a significant decrease in the deposition rate. When plasma-assisted bombardment is introduced, the high-pressure gas environment generates a strong collision scattering effect. High-energy ions undergo inelastic collisions with gas molecules during acceleration. This energy loss makes it difficult for ions to induce deep lattice dislocations during the crystal coarsening stage, failing to eliminate the anisotropy of the structure.

[0003] Conventional processes attempt to improve coating quality by adjusting the total chamber pressure or increasing the bombardment power, but fail to avoid the scattering obstruction of dense gas phase molecules. This passive adjustment method based on overall parameters cannot match the microscopic transients of thin film nucleation. Blindly injecting ion kinetic energy not only fails to cut off the longitudinal growth path of columnar crystals but may also cause substrate overheating, resulting in the service life of the sealing surface reinforcement layer failing to meet expectations. In addition to the aforementioned hardware limitations such as specific reaction chamber structures or roller morphology fittings, existing technologies also have shortcomings in software-level process control methods. For example, Chinese invention patent application CN105714292A discloses a surface hardening treatment method for a hard-seal ball valve sealing pair, which involves first spraying a nickel-based alloy and then superimposing a physical vapor deposition method. The composite hardened layer is constructed by simply stacking static processes and setting an overall hardness gradient to improve the wear resistance of the sealing surface. The control method implicitly relies on idealized energy transfer and interface bonding presets, which is out of the objective thermodynamic limitations of the micro-evolution process of high-pressure vapor deposition. In the complex actual dynamic deposition environment, high-energy particles will inevitably encounter disordered collisions and strong scattering of gas molecules. Based on the basic physical collision law, kinetic energy decay occurs, making it impossible for conventional static parameter stacking to accurately intervene in crystallization dynamics at the initial stage of crystal germination. The scheme fails to penetrate the overall coating stacking appearance to accurately capture the transient window of the micro-phase transition of the thin film. As a result, the kinetic energy of ions is easily dissipated disorderly on the periphery of the sealing surface, which cannot induce deep lattice dislocations to cut off the longitudinal epitaxial growth of columnar crystals. Excess heat enthalpy is easily accumulated at the overall interface, inducing thermal stress concentration.

[0004] Therefore, how to capture the microscopic phase transition nodes in the deposition process and use the gas phase depletion transient to implement ballistic penetration energy injection in order to cut off the epitaxial growth path of columnar crystals and improve the coating density has become the technical problem to be solved by this invention. Summary of the Invention

[0005] In this technical solution, a vapor deposition process for strengthening valve sealing surfaces includes the following steps: Step 101: Place the valve body in the vacuum chamber, heat the valve body using the heating control unit, set the temperature of the valve body to 450°C to 480°C, and turn on the temperature control loop to maintain the thermal stability of the valve body. Step 102: Introduce a precursor gas into the vacuum chamber to create a vapor deposition environment on the sealing surface of the valve substrate, so as to induce heterogeneous nucleation of the reinforcement layer on the sealing surface. Step 103: Use the pressure monitoring unit installed in the vacuum chamber to collect the pressure fluctuation signal in the near wall area of ​​the sealing surface, and determine the transient pressure drop rate caused by the consumption of precursor gas in the near wall area of ​​the sealing surface based on the pressure fluctuation signal. Step 104: Compare the transient pressure drop rate with the preset pressure transition threshold. When the transient pressure drop rate reaches or exceeds the pressure transition threshold, it is determined that the near-wall area of ​​the sealing surface has entered the gas phase depletion stage where the precursor gas concentration decreases, and the low collision cross-section area where the mean free path of ions increases in the gas phase deposition environment is identified. Step 105: During the gas phase depletion stage, an RF negative bias voltage with an amplitude of -300V to -600V is applied to the valve substrate to accelerate the ions generated by the plasma source through the low collision cross-section region, so that the ions impact the nuclei on the sealing surface with peak kinetic energy and induce dislocations inside the crystal of the reinforcement layer to block the longitudinal epitaxial growth of columnar crystals.

[0006] Preferably, in step 101, the heating control unit adjusts the heating power according to the real-time temperature signal collected by the thermocouple, so that the temperature fluctuation range of the valve substrate is within ±2℃; in step 105, the duty cycle of the radio frequency negative bias is set to 15% to 25%, and the total amount of energy injection is determined by limiting the pulse width of ion bombardment, thereby constructing a residual compressive stress field inside the reinforcement layer.

[0007] Preferably, after the ion bombardment action in step 105 is completed, the process further includes: step 301, injecting high-purity argon carrier gas into the sealing surface area; step 302, using the adiabatic expansion process generated by the high-purity argon carrier gas in the sealing surface area to absorb the residual heat generated by the ion bombardment, and independently absorbing the transient enthalpy of the surface micro-region at the top of the nucleus of the sealing surface through convection heat transfer, so that the transient local temperature of the sealing surface returns to within 450°C to 480°C.

[0008] Preferably, the precursor gas includes a vapor containing a metal element and a reactant gas; the vapor containing the metal element is selected from chromium vapor, titanium vapor, or aluminum vapor; and the reactant gas is selected from nitrogen, methane, or oxygen.

[0009] Preferably, in step 104, the pressure transition threshold is adjusted according to the flow rate of the precursor gas. When the flow rate of the precursor gas increases, the active gas rapidly replenished into the vacuum chamber produces a macroscopic backfilling effect in terms of fluid dynamics. This dynamic gas replenishment effectively offsets the sudden drop in local transient pressure caused by the consumption of precursor molecules by heterogeneous nucleation and crystallization on the sealing surface. As a result, the fluctuation rate of pressure drop in the microscopic closed flow field near the wall of the sealing surface, which is actually collected by the pressure monitoring unit, slows down, and the absolute value of the pressure transition threshold decreases accordingly.

[0010] Preferably, in step 301, the injection pressure of the high-purity argon carrier gas is 0.5 MPa to 1.2 MPa higher than the deposition pressure inside the vacuum chamber; the sealing surface is physically cleaned by the jet gas generated by the pressure gradient.

[0011] Preferably, the frequency of the radio frequency negative bias is set according to the transit time of ions through the low collision cross-section region, so that the acceleration path of the ions is synchronized with the pulse period of the radio frequency negative bias.

[0012] Preferably, in step 103, the pressure monitoring unit includes a piezoelectric thin film sensor disposed on the wall of the vacuum chamber; the piezoelectric thin film sensor captures pressure pulses near the wall and transmits the pressure signal to the control unit to calculate the transient pressure drop rate.

[0013] Compared with existing technologies, the vapor deposition process for strengthening valve sealing surfaces in this invention has the following advantages: 1. In the vapor deposition process for strengthening valve sealing surfaces, by establishing a physical mapping between transient pressure drop rate and microcrystalline kinetics, an isometric transformation of the deposited layer's microstructure is induced. This process monitors the vacuum reaction chamber... The system locks in the critical transient state of precursor gas nucleation and consumption on the sealing surface, thereby intervening with high-energy bombardment in the initial stage of three-dimensional island coarsening of the grains. This precise intervention mechanism forcibly cuts off the epitaxial growth path of the grains along the vertical direction, transforming the film layer from a loose columnar crystal structure into a dense equiaxed nanocrystal alternating structure, cutting off the propagation channel of through cracks caused by stress concentration, and improving the fatigue spalling strength of the valve sealing surface under heavy load opening and closing conditions.

[0014] 2. Based on the ballistic penetration mechanism of the gas phase depletion interface, the effective conversion efficiency of plasma energy at the deposition interface is improved. This process uses the local low-density region generated by the large consumption of precursor gas as an energy transmission channel. Under the acceleration of the applied radio frequency negative bias voltage, high-energy argon ions avoid kinetic energy scattering collisions with dense gas phase molecules. The high-energy ions act on the top of the newly formed crystal nuclei with unattenuated peak kinetic energy, deeply injecting collision energy into the crystal lattice and inducing high-density dislocations. This utilization method generates a residual compressive stress field without changing the overall deposition rate, which enhances the interfacial anchoring force between the coating and the valve substrate.

[0015] 3. By synergistically utilizing the pulsed thermal unloading process and the high-energy particle bombardment process, the overall temperature field of the valve substrate is kept in steady equilibrium. After each ion bombardment, high-purity argon carrier gas is injected immediately. The adiabatic expansion process of the gas flow in the micro-morphological region of the sealing surface is used to instantly absorb the residual enthalpy generated by ion collisions. The low-temperature carrier gas is forced to carry away the accumulated heat through convection, ensuring that the temperature fluctuation of the valve substrate is always within the target range of 450℃ to 480℃. This thermodynamic management method solves the problem of substrate material softening or unexpected phase transformation caused by local temperature rise during the thick film preparation process, and ensures the overall mechanical performance of the sealing components. Attached Figure Description

[0016] Figure 1 This is a flowchart of the steps of the vapor deposition strengthening process for the valve sealing surface of the present invention; Figure 2 This is a system control and interaction use case diagram of the vapor deposition enhancement process of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0018] It should be noted that all directional and positional terms used in this invention, such as: up, down, left, right, front, back, vertical, horizontal, inner, outer, top, bottom, transverse, longitudinal, center, etc., are only used to explain the relative positional relationship and connection between the components in a specific state (as shown in the accompanying drawings), and are only for the convenience of describing this invention, not to require that this invention be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In addition, the descriptions of "first," "second," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly indicating the number of technical features indicated.

[0019] In the description of this invention, unless otherwise explicitly specified and limited, the terms installation, connection, and linking should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood in conjunction with the specific circumstances.

[0020] In the description of this specification, references to the terms "an embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example, and the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0021] A vapor deposition process for strengthening valve sealing surfaces includes the following steps: Step 101: Place the valve body in the vacuum chamber, heat the valve body using the heating control unit, set the temperature of the valve body to 450°C to 480°C, and turn on the temperature control loop to maintain the thermal stability of the valve body. Step 102: Introduce a precursor gas into the vacuum chamber to create a vapor deposition environment on the sealing surface of the valve substrate, so as to induce heterogeneous nucleation of the reinforcement layer on the sealing surface. Step 103: Use the pressure monitoring unit installed in the vacuum chamber to collect the pressure fluctuation signal in the near wall area of ​​the sealing surface, and determine the transient pressure drop rate caused by the consumption of precursor gas in the near wall area of ​​the sealing surface based on the pressure fluctuation signal. Step 104: Compare the transient pressure drop rate with the preset pressure transition threshold. When the transient pressure drop rate reaches or exceeds the pressure transition threshold, it is determined that the near-wall area of ​​the sealing surface has entered the gas phase depletion stage where the precursor gas concentration decreases, and the low collision cross-section area where the mean free path of ions increases in the gas phase deposition environment is identified. Step 105: During the gas phase depletion stage, an RF negative bias voltage with an amplitude of -300V to -600V is applied to the valve substrate to accelerate the ions generated by the plasma source through the low collision cross-section region, so that the ions impact the nuclei on the sealing surface with peak kinetic energy and induce dislocations inside the crystal of the reinforcement layer to block the longitudinal epitaxial growth of columnar crystals.

[0022] Preferably, in step 101, the heating control unit adjusts the heating power according to the real-time temperature signal collected by the thermocouple, so that the temperature fluctuation range of the valve substrate is within ±2℃; in step 105, the duty cycle of the radio frequency negative bias is set to 15% to 25%, and the total amount of energy injection is determined by limiting the pulse width of ion bombardment, thereby constructing a residual compressive stress field inside the reinforcement layer.

[0023] Preferably, after the ion bombardment action in step 105 is completed, the process further includes: step 301, injecting high-purity argon carrier gas into the sealing surface area; step 302, using the adiabatic expansion process generated by the high-purity argon carrier gas in the sealing surface area to absorb the residual heat generated by the ion bombardment, and independently absorbing the transient enthalpy of the surface micro-region at the top of the nucleus of the sealing surface through convection heat transfer, so that the transient local temperature of the sealing surface returns to within 450°C to 480°C.

[0024] Preferably, the microstructure density factor Γ of the reinforcement layer satisfies the following relationship: Where Γ is the micro density factor of the reinforcement layer, Let λ be the peak kinetic energy of the ion when it reaches the sealing surface, and λ be the mean free path of the low collision cross-section region. This refers to the local gas pressure in the near-wall region of the sealing surface during the gas phase depletion stage.

[0025] Preferably, the precursor gas includes a vapor containing a metal element and a reactant gas; the vapor containing the metal element is selected from chromium vapor, titanium vapor, or aluminum vapor; and the reactant gas is selected from nitrogen, methane, or oxygen.

[0026] Preferably, in step 104, the pressure transition threshold is adjusted according to the flow rate of the precursor gas. When the flow rate of the precursor gas increases, the active gas rapidly replenished into the vacuum chamber produces a macroscopic backfilling effect in terms of fluid dynamics. This dynamic gas replenishment effectively offsets the sudden drop in local transient pressure caused by the consumption of precursor molecules by heterogeneous nucleation and crystallization on the sealing surface. As a result, the fluctuation rate of pressure drop in the microscopic closed flow field near the wall of the sealing surface, which is actually collected by the pressure monitoring unit, slows down, and the absolute value of the pressure transition threshold decreases accordingly.

[0027] Preferably, in step 301, the injection pressure of the high-purity argon carrier gas is 0.5 MPa to 1.2 MPa higher than the deposition pressure inside the vacuum chamber; the sealing surface is physically cleaned by the jet gas generated by the pressure gradient.

[0028] Preferably, the frequency of the radio frequency negative bias is set according to the transit time of ions through the low collision cross-section region, so that the acceleration path of the ions is synchronized with the pulse period of the radio frequency negative bias.

[0029] Preferably, in step 103, the pressure monitoring unit includes a piezoelectric thin film sensor disposed on the wall of the vacuum chamber; the piezoelectric thin film sensor captures pressure pulses near the wall and transmits the pressure signal to the control unit to calculate the transient pressure drop rate.

[0030] Example 1: Heavy-load valves in a high-pressure fluid pipeline system experience frequent opening and closing, generating tangential shear stress on the sealing surface and fluid erosion. Continuous vapor deposition (CVD) processes, driven by the principle of minimum energy, induce penetrating columnar epitaxial growth. Tangential stress penetrates along coarse grain boundaries, causing cleavage fracture in the coating. Lowering the reaction temperature limits kinetic growth, leading to a decrease in precursor conversion rate and deposition stagnation. A piezoelectric thin-film sensor within the vacuum chamber continuously collects pressure fluctuation signals in the near-wall region of the sealing surface. The time derivative of the pressure fluctuation signal is extracted to calculate the transient pressure drop rate. The transient pressure drop rate With pressure transition threshold Real-time comparison, including pressure transition threshold. The slope of the local pressure drop difference between introducing argon carrier gas alone and introducing a mixture containing precursor gas is determined based on the total pressure of the same basic chamber.

[0031] When the transient pressure drop rate Reaching or exceeding the pressure transition threshold At that time, it was determined that the near-wall region of the sealing surface had entered the gas phase depletion stage, where the precursor gas concentration decreased, and a low collision cross-section region with increased ion mean free path was identified in the gas deposition environment. During the gas phase depletion stage, a radio frequency negative bias voltage with an amplitude of -300V to -600V was applied to the valve substrate, which maintained a thermally stable state of 450℃ to 480℃. The radio frequency negative bias voltage accelerated the ions generated by the plasma source through the low collision cross-section region. The ions avoided scattering by gas phase molecules and impacted the nuclei on the sealing surface with peak kinetic energy. The ion impact strengthened the... Dislocations are induced within the crystal layer, blocking the longitudinal epitaxial growth of columnar crystals. The duty cycle of the radio frequency negative bias is set to 15% to 25%. After the radio frequency negative bias pulse cycle ends, high-purity argon carrier gas with a pressure 0.5 MPa to 1.2 MPa higher than the deposition pressure in the vacuum chamber is injected into the sealing surface region. The local pressure gradient drives the jet gas to generate adiabatic expansion on the sealing surface. To avoid the convective heat transfer mechanism falling into a thermodynamic black box without boundaries, the duration of one high-purity argon pulse injection is locked at 200 ms within the control system. The transient mass flow rate is constantly limited to 800 sccm by the mass flow meter and mapped to the 85 cm² effective metal heat transfer surface area of ​​the valve substrate exposed to the plasma. Based on this clearly defined thermodynamic boundary, the cooling capacity is precisely output. Through convective heat transfer, the transient enthalpy generated by ion bombardment is absorbed, causing the surface temperature of the valve substrate to return to the 450°C to 480°C range. In fact, the above convective heat transfer mechanism is physically valid because the radio frequency negative bias applied by the high-power plasma is 15% to 25%... The extremely low duty cycle high-frequency chopping strictly cuts off the heat accumulated by high-energy ion bombardment, which actually manifests as transient thermal shock in a very shallow micro-region, and the thermal shock depth is limited to the top of the nanoscale nuclei. The tiny adiabatic expansion of high-purity argon is precisely triggered at the time point. Before the transient enthalpy of the aforementioned surface micro-regions diffuses into the macroscopic bulk valve matrix through phonon conduction, it is forcibly absorbed at the solid-gas interface by a microscopic surface cooling capacity of matching magnitude, thus avoiding the scale mismatch between macroscopic heat load and microscopic cooling capacity.

[0032] An annular gas distributor is arrayed around the sealing surface of the valve substrate within the vacuum reaction chamber. This annular gas distributor is equipped with a sequence of micro-orifice nozzles tilted at a fixed angle towards the sealing surface. When the radio frequency negative bias pulse period limit is reached, the system delivers high-purity argon carrier gas to the micro-orifice nozzle sequence. The high-purity argon carrier gas is injected into the near-wall region of the sealing surface via the micro-orifice nozzle sequence. The throttling resistance of the micro-orifice nozzle sequence maintains the back pressure of the gas pipeline, causing the injected gas to undergo adiabatic volume expansion on the surface region of the sealing surface after leaving the nozzles. The thermodynamic energy of the gas phase fluid is converted into overall kinetic energy, and the convective heat transfer mechanism absorbs the transient enthalpy accumulated by ion bombardment. A piezoelectric thin-film sensor is nested on the back-flow side of the annular gas distributor. The pressure-sensing end of the piezoelectric thin-film sensor is covered with a grounded metal shield. The grounded metal shield intercepts the high-energy particle flow of the plasma. The pressure-sensing end of the piezoelectric thin-film sensor collects the hydrostatic pressure component of the fluid through a pressure-conducting capillary tube connected to the near-wall region of the sealing surface, outputting a pressure fluctuation signal. The parameter variables during the deposition process follow the formula... Where Γ is the density factor of the reinforcement layer, Let λ be the peak kinetic energy of the ion when it reaches the sealing surface, and λ be the mean free path of the low collision cross-section region. To address the local gas pressure near the wall surface of the sealing surface during the gas phase depletion stage, and to eliminate physical faults caused by dimensional mismatches, the system, when calculating the density factor in its underlying logic, forcibly multiplies the rough calculation result obtained from the product of the above formula by an empirical conversion base with a value of 1 and a dimension of N⁻². This linearly maps the intermediate calculated value representing the overall energy dissipation state, outputting a final microscopic density factor in m². This physical quantity serves as a quantitative benchmark for evaluating equiaxed crystal growth. The pressure monitoring and ion bombardment steps are repeated until the thickness of the reinforcing layer reaches 30 μm to 50 μm, dense dislocations cut off the columnar crystal boundaries, and the growth morphology of the vapor-deposited layer transforms into an equiaxed crystal structure. This structure improves the sealing surface's resistance to tangential shear stress. During the execution of this process, the data written to the system register... The transit time refers to the average flight time consumed when ions generated by the plasma source undergo gas phase depletion, nucleation and crystallization in the micro-region of the valve sealing surface, resulting in the severe consumption of precursor molecules. Under the directional acceleration bias electric field constructed by the applied radio frequency negative bias, the high-energy ions start from the initial edge of the transient vacuum boundary layer of the low collision cross-section region (a few millimeters thick), accelerate linearly along the ballistic penetration channel, and cross this microscopic spatial distance until they finally collide with the top surface of the nucleus that germinates on the sealing surface. The control system extracts this transit time to accurately set the operating frequency of the radio frequency negative bias, thereby achieving strict spatiotemporal synchronization between the acceleration path of the high-energy ions and the pulse period of the radio frequency negative bias under high-frequency chopping, ensuring that the total energy injection achieves deep conversion without causing macroscopic overheating of the substrate.

[0033] Example 2: To address the coating cleavage fracture problem of heavy-duty valve sealing surfaces in high-pressure fluid pipeline systems under pressure fluctuations and tangential shear stress, a verification platform was constructed using a vacuum reaction chamber equipped with a piezoelectric thin-film sensor and a substrate heating stage. The piezoelectric thin-film sensor has a measurement resolution of 0.1 Pa and a sampling rate of 10 kHz. The temperature control accuracy of the substrate heating stage is set within ±0.5℃. The system continuously applies mechanical vibration at a frequency of 50 Hz to the base of the vacuum reaction chamber, introducing periodic thermal drift with an amplitude of ±2.5℃ to simulate the pump body vibration and fluid thermal disturbance environment in the pipeline system. A pressure change threshold was set. Balancing precursor depletion sensing sensitivity with background turbulence false triggering rate, and considering the increase in background pressure fluctuation spectrum bandwidth in the near-wall region of the sealing surface with mechanical vibration, the slope calibration data of the local pressure drop difference between introducing argon carrier gas alone and introducing a mixture containing precursor gas are extracted under the same basic chamber total pressure conditions, and the pressure transition threshold is increased. To avoid signal aliasing and misjudgment caused by mechanical vibration, the system sets precise pressure change thresholds based on calibration data and the current excitation conditions. The value is 15.4 Pa / s.

[0034] The verification platform was divided into control group 1, control group 2, control group 3, extreme value verification group A, extreme value verification group B, and experimental group. Control group 1 maintained continuous gas phase deposition, with the RF negative bias output cut off throughout the process, and the injection of high-pressure argon carrier gas stopped. Control group 2 and control group 3 respectively verified the parameter boundary effect of RF negative bias. Control group 2 applied an RF negative bias with an amplitude of -200V; control group 3 applied an RF negative bias with an amplitude of -700V. Extreme value verification group A was used to verify the lower limit boundary of the process technical parameter range. The valve substrate temperature was set to 450℃, an RF negative bias with an amplitude of -300V and a duty cycle of 15% was applied, and high-purity argon carrier gas with a pressure 0.5MPa higher than the chamber deposition pressure was injected after the pulse cycle. Extreme value verification group B was used to verify the upper limit boundary of the process technical parameter range. The valve substrate temperature was set to 480℃, an RF negative bias with an amplitude of -600V and a duty cycle of 25% was applied, and high-purity argon carrier gas with a pressure 1.2MPa higher than the chamber deposition pressure was injected after the pulse cycle. Throughout the entire vapor deposition reaction cycle, the heating control unit continuously reads thermocouple signals and executes closed-loop power regulation. The pressure monitoring unit and control system monitor and record the actual temperature changes of each group throughout the process: the actual temperature fluctuation range of extreme value verification group A during the reaction process is between -2℃ and +0.6℃; the actual temperature fluctuation range of extreme value verification group B under small thermal drift is between -0.7℃ and +1.1℃; and the actual temperature fluctuation range of the test group during the reaction process is between -0.4℃ and +2℃. Experimental monitoring data definitively demonstrates that the actual temperature fluctuation accuracy of extreme value verification group A, extreme value verification group B, and the experimental group was strictly controlled within the preset technical index of ±2℃, effectively eliminating the abnormal macroscopic temperature rise induced by plasma-assisted ion bombardment pulses. To further verify the independent microscopic cooling effect of high-purity argon injection on the residual heat of ion bombardment without relying on dynamic adjustment of the heating control unit, the testers introduced heating output freezing verification tests into the process flows of the experimental group, extreme value verification group A, and extreme value verification group B: during each round of ion bombardment and subsequent argon... During the gas injection cycle, the PID closed-loop output power of the heating control unit is temporarily frozen to maintain a constant static background power. Simultaneously, an ultra-high-speed infrared dual-color thermometer with a response time in the microsecond range is used to monitor the transient temperature evolution of the surface micro-region at the top of the germinating crystal nucleus on the sealing surface. Monitoring data shows that within the instantaneous window of high-energy ion bombardment at a radio frequency negative bias of -450V and a duty cycle of 20%, the extremely shallow surface layer at the top of the germinating crystal nucleus experiences a localized transient thermal shock temperature rise due to high-frequency energy injection, resulting in a sudden increase in the local temperature of the micro-region. Subsequently, the radio frequency negative bias is cut off, and the high-purity argon carrier gas is injected at 0...Within the 200ms instantaneous window of 8MPa injection, due to the adiabatic volume expansion and forced convection heat transfer induced by the micro-orifice nozzle sequence, the excess enthalpy generated by the transient thermal shock in this micro-region is rapidly and forcibly absorbed within the first 120ms after the intake starts, resulting in an extremely steep transient cooling drop in the surface temperature of the micro-region. These experimental results conclusively demonstrate that, under the independent action of completely cutting off the dynamic intervention of the heating control unit and relying solely on the adiabatic expansion cooling of the high-purity argon carrier gas, not only can the transient local temperature of the micro-region on the sealing surface of the test group be reduced... The temperature steadily returned to 465.2℃ before the argon pulse ended. Simultaneously, in-situ temperature measurements confirmed that the transient micro-region temperature of the sealing surface in extreme value verification group A steadily returned to 450℃ before the argon pulse ended, and the transient micro-region temperature of the sealing surface in extreme value verification group B steadily returned to 480℃ before the argon pulse ended. These isolated variable experimental data definitively demonstrate the precise independent thermal balance between the argon gas flow's microscopic surface cooling capacity and the cumulative enthalpy of the ion bombardment pulse on a microscopic spatiotemporal scale, eliminating analytical ambiguities. The experimental groups were fully utilized... The entire process involves applying a radio frequency negative bias voltage of -450V with a duty cycle of 20% to the valve substrate, which is maintained at a thermally stable state of 465.5℃. After the pulse cycle ends, a high-purity argon carrier gas with a pressure 0.8MPa higher than the chamber deposition pressure is injected. A piezoelectric thin-film sensor collects the original pressure fluctuation signal superimposed with mechanical vibration noise. This original signal exhibits a disordered jitter state with amplitude fluctuations of ±3.2Pa. To ensure the discrete consistency and feasibility of subsequent time-domain conversion and differential operations, the system controller internally opens two memory buffer blocks to construct a sliding feature sampling mechanism. Each time, 512 pressure sampling points are read to form a complete data frame. The overlap rate between two adjacent data frames is forcibly set to 75% through a software pointer, that is, the sliding step span is limited to 128 sampling points. This eliminates the statistical black box and takes into account the characteristic continuity under 10kHz high-frequency sampling. The system extracts the time derivative of the original signal, uses a low-pass digital filter to filter out the high-frequency mechanical jitter component, and calculates the transient pressure drop rate. The transient pressure drop rate during a specific period of the reaction cycle It climbed to 16.8 Pa / s, a value that crosses the pressure transition threshold of 15.4 Pa / s. Based on this, the system determines the gas phase depletion stage and triggers a radio frequency negative bias output in the low collision cross-section region. The transient pressure drop rate of up to 16.8 Pa / s recorded here does not refer to a global drop in the total amount of gas in the macroscopic reaction chamber of hundreds of liters. Rather, it is because the pressure-sensing end face of the piezoelectric thin film sensor strictly restricts its fluid collection space to a microscopic closed flow field on the local wall of the sealed surface through the pressure-conducting capillary tube. When nanoscale precursor molecules rapidly bond and crystallize at the gas-solid interface in this confined microflow field, even a very small amount of absolute molecular gas loss is enough to be reflected as an extremely steep local concentration gradient and a huge micro-region pressure drop rate within a very short time window under the action of the denominator of the extremely small volume of the microflow field. This makes the microscopic crystal nucleus depletion event legally converted into transient characteristics that can be captured by macroscopic instruments on a physical scale.

[0035] The testers measured the microstructure and thickness data of the coating cross-section of each group of samples. The coating cross-section of control group one showed a columnar crystal morphology with continuous epitaxial growth, and the longitudinal length of a single columnar crystal reached 28.5 μm. The corresponding ion peak kinetic energy of control group two was lower, and the instrument measured the dislocation density induced inside its crystal to be 2.1 × 10¹. 4 m⁻², failing to cut the epitaxial path of the columnar crystal. In control group three, after the RF negative bias voltage exceeded the upper limit of -600V, energy deposition turned into material peeling. The reverse sputtering effect caused the actual deposition thickness of the coating to stagnate at 11.3μm. The crystal dislocation density measured on the coating cross section of extreme value verification group A reached The microstructure also transformed into a dense equiaxed alternating crystal structure, ultimately forming a reinforced layer with a total thickness of 30.8 μm; the dislocation density of the crystal measured on the coating cross-section of extreme value verification group B reached... The microstructure also exhibits a uniformly distributed equiaxed crystal structure, and the total thickness of the final reinforced layer is 48.9 μm; the dislocation density of the coating cross-section in the experimental group reaches 8.7 × 10¹. 5The microstructure transforms into a dense alternating equiaxed grain structure at m⁻², and the adiabatic expansion cooling mechanism absorbs the temperature fluctuations caused by transient enthalpy, maintaining the thermal stability of the matrix and forming a reinforcing layer with a total thickness of 42.5 μm. The testing equipment applied gradient tangential shear stresses of 50 MPa, 100 MPa, and 150 MPa to the sealing surfaces of the above-mentioned samples, respectively, and measured the physical response of the reinforcing layer under increasing mechanical loads. Under a tangential shear stress of 100 MPa, control group 1 developed a through-crack along the coarse grain boundaries after 12.4 hours of operation; control group 2 experienced blocky cleavage spalling after 45.2 hours of operation. Under gradient tangential shear stresses of 50 MPa, 100 MPa, and 150 MPa, the crack-free operating life of extreme value verification group A reached 386.4 hours, 342.1 hours, and 302.8 hours, respectively. The crack-free operating life of B reached 398.2 hours, 365.4 hours and 318.5 hours, respectively. Under gradient tangential shear stress of 50 MPa, 100 MPa and 150 MPa, the crack-free operating life of the experimental group reached 412.5 hours, 385.2 hours and 341.7 hours, respectively. As the tangential shear stress increased in a gradient, the crack-free operating life of the experimental group showed a convergent decay in accordance with the fatigue damage law, maintaining a stable anti-stripping physical state. The spatiotemporal alignment of the radio frequency negative bias window and the local gas phase depletion region drove high-energy ions to penetrate along the low collision cross section region, transforming the phase transition state of the precursor depletion into a lattice dislocation source that blocks the epitaxial growth of columnar crystals. The equiaxed alternating structure promoted by the dense dislocations cut off the stress penetration channel of the grain boundary, enabling the strengthening layer to adapt to the shear fatigue requirements of heavy-load high-frequency start-stop conditions.

[0036] Example 3: During the vapor deposition process at the valve sealing surface, which is subject to mechanical background noise and fluid thermal disturbance, capturing the precursor gas depletion stage is hampered by the low signal-to-noise ratio of the original sensor signal and the difficulty in quantifying the trigger threshold. To address the issue of false or delayed triggering of the pressure monitoring system under specific operating conditions, the control system initiates an in-situ calibration process for the pressure transition threshold before introducing the precursor gas to start vapor deposition. The system injects high-purity argon carrier gas separately into the vacuum reaction chamber, which maintains a thermally stable state of 450°C to 480°C. After the system stabilizes at the preset deposition pressure, the inlet pipeline is cut off. The pressure monitoring unit collects chamber pressure data within a preset time period at a sampling rate of 10kHz. The control system calculates the first-order difference result from the pressure data, which serves as the argon reference pressure drop slope. The system empties the vacuum reaction chamber and refills it with a mixture containing the precursor gas to the same deposition pressure. The control system collects pressure data at the same sampling rate and calculates the slope of the mixed gas pressure drop. The control system is based on the formula Determine the pressure transition threshold ;in, The pressure transition threshold, The slope of the pressure drop of the mixture. The slope of the argon reference pressure drop is given by , and k is the operating condition compensation coefficient, with a value range limited to 0.85 to 0.95.

[0037] During the vapor deposition stage, the pressure monitoring unit continuously acquires pressure fluctuation signals in the near-wall region of the sealing surface. The control system constructs a sliding data window with 512 sampling points. The control system receives and stores the pressure fluctuation signals within this sliding data window. The control system sets the cutoff frequency of the low-pass Butterworth filter to 100Hz. The control system uses this low-pass Butterworth filter to process the pressure sequence within the sliding data window, filtering out high-frequency interference components caused by pipeline mechanical vibration and heating table thermal drift. The control system then calculates the first derivative of the filtered pressure sequence based on the time vector to generate the transient pressure drop rate. The control system will control the transient pressure drop rate. With pressure transition threshold The comparator continuously inputs data, and the comparator determines the transient pressure drop rate. Reaching or exceeding the pressure transition threshold At this time, the control system sends a trigger command to the RF power supply, which applies an RF negative bias voltage with an amplitude of -300V to -600V to the valve substrate. The threshold calibration and signal filtering process converts the concentration change during the gas phase depletion stage into a quantized trigger condition. This quantized trigger condition eliminates the interference path of external environmental disturbances on the plasma energy injection timing, allowing ions to pass through the low collision cross-section region and induce lattice dislocations inside the strengthening layer, maintaining the continuous growth of the equiaxed crystal structure. During this control process, when the flow rate of the precursor gas increases, the active oxygen rapidly replenishes the vacuum chamber. The presence of reactive gases creates a macroscopic backfilling effect in fluid dynamics. This dynamic intake replenishment effectively counteracts the sudden drop in local transient pressure at the sealing surface caused by the consumption of precursor molecules due to heterogeneous nucleation and crystallization. Consequently, the rate of pressure drop within the microscopic closed flow field near the sealing surface, as actually collected by the pressure monitoring unit, slows down. Therefore, to ensure that the control system can still generate sufficiently sensitive and timely phase change sensing responses to extremely weak local microscopic concentration depletion under high-speed intake replenishment conditions, and to avoid delayed or missed triggering, the preset pressure transition threshold must be actively and correspondingly reduced. The absolute value of this value is used to dynamically match the thermodynamic and kinetic evolution of micro-film formation.

[0038] Example 4: When a newly designed heavy-duty valve is connected to the fluid pipeline network, the control system continuously introduces high-purity argon gas into the vacuum reaction chamber before introducing the precursor gas and maintains a preset deposition pressure. The pressure monitoring unit collects the initial background pressure fluctuation signal for five minutes at a sampling rate of 10 kHz. The control system extracts the noise peak amplitude of the initial background pressure fluctuation signal in the frequency domain as the baseline disturbance parameter and inputs it into the preset compensation model to calculate the initial operating condition compensation coefficient k for the specific valve configuration. The compensation model uses the ratio of the baseline disturbance parameter to the standard no-load disturbance parameter of the vacuum reaction chamber as an independent variable to generate a coefficient output value in the range of 0.85 to 0.95. After obtaining the initial operating condition compensation coefficient k, the control system measures the argon gas reference pressure drop slope. With the slope of the mixed gas pressure drop And substitute the three into the formula Determining the pressure transition threshold .

[0039] The control system initiates the vapor deposition step and continuously acquires the transient pressure drop rate. The value, when the comparator records the transient pressure drop rate over three consecutive verification cycles. Reaching the pressure transition threshold When the time node variance exceeds the preset time tolerance window, the control system adjusts the value of the initial operating condition compensation coefficient k downwards in a fixed step size of 0.01 until the time node variance falls back into the time tolerance window. The adjusted RF negative bias voltage output timing matches the physical state of gas phase depletion in the near-wall region of the sealing surface. High-energy ions generated by the plasma source pass through the low collision cross-section region and induce lattice dislocations inside the reinforcement layer. Equiaxed alternating crystal structures continue to grow on the surface of the valve substrate. The aforementioned low collision cross-section region is not constructed by any physical macroscopic physical partition, but utilizes the hydrodynamic hysteresis effect of the rate at which precursor molecules are violently consumed when microscopic crystal nuclei converge on the sealing surface, which is much greater than the rate at which the background gas flow in the macroscopic chamber diffuses and backfills into this region. Within this microscopic hysteresis time window, a transient vacuum deep recess region with a sharp decrease in molecular number density is naturally formed in the gas boundary layer a few millimeters thick close to the sealing surface, thus naturally providing an ion ballistic penetration channel that avoids violent gas phase collisions and energy scattering.

[0040] Example 5: When the system faces the condition of deploying a vapor deposition device at a fluid pipeline node with unknown mechanical resonance characteristics, the control system initiates the parameter calibration process of the pressure monitoring unit before introducing the precursor gas; it drives the piezoelectric exciter on the vacuum reaction chamber base to emit a linear sweep frequency signal covering a frequency range of 10Hz to 1000Hz, and uses a piezoelectric thin film sensor to collect the chamber base pressure echo sequence corresponding to the linear sweep frequency signal at a sampling rate of 10kHz; the control system calls the fast Fourier transform algorithm to process the chamber base pressure echo sequence, extracts the peak frequency point whose spectral amplitude is greater than three times the baseline noise level, and determines it as the characteristic resonant frequency of the pipeline network. The control system is based on the formula Calculate the length N of the sliding data window; where N is the length of the sliding data window. Sampling rate, The characteristic resonant frequency of the pipeline network, As the window overlap coefficient, the control system sets the cutoff frequency of the low-pass Butterworth filter to the characteristic resonant frequency of the pipeline network. 0.8 times.

[0041] The control system introduces high-purity argon gas into the vacuum reaction chamber and ignites the test plasma. An infrared thermometer continuously monitors the temperature rise rate on the valve substrate surface. The control system extracts the temperature rise rate and inputs it into the duty cycle mapping matrix to find the corresponding upper limit of the RF negative bias duty cycle. The duty cycle mapping matrix is ​​constructed based on a steady-state heat transfer offline calibration experiment under constant plasma power. This offline calibration experiment fixes the operating output power of the plasma RF power supply at 1500W, limits the reference operating back pressure of the vacuum reaction chamber to 2.5Pa, and specifies a specific heat capacity of 500J / (kg·K). The valve substrate, made of 304 stainless steel (K), serves as the heat-bearing object. Calibration is performed under the premise that the above three core physical boundary conditions are completely locked, and the numerical correspondence between the temperature rise rate and the heat generation balance of ion collisions is recorded. The control system limits the duty cycle of the radio frequency negative bias to the range formed by the upper limit value obtained by consulting the duty cycle mapping matrix and the value of 5% downward, thereby regulating the total plasma energy injection. The control system writes the determined sliding data window length N and the radio frequency negative bias duty cycle parameters into the system register, and the vapor deposition process maintains the thermophysical steady state of phase change sensing and deposition control.

[0042] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit of this application and the scope of protection of this invention, and all of these forms are within the protection scope of this application.

Claims

1. A vapor deposition process for strengthening valve sealing surfaces, characterized in that, Includes the following steps: Step 101: Place the valve body in the vacuum chamber, heat the valve body using the heating control unit, set the temperature of the valve body to 450°C to 480°C, and turn on the temperature control loop to maintain the thermal stability of the valve body. Step 102: Introduce a precursor gas into the vacuum chamber to create a vapor deposition environment on the sealing surface of the valve substrate, so as to induce heterogeneous nucleation of the reinforcement layer on the sealing surface. Step 103: Use the pressure monitoring unit installed in the vacuum chamber to collect the pressure fluctuation signal in the near wall area of ​​the sealing surface, and determine the transient pressure drop rate caused by the consumption of precursor gas in the near wall area of ​​the sealing surface based on the pressure fluctuation signal. Step 104: Compare the transient pressure drop rate with the preset pressure transition threshold. When the transient pressure drop rate reaches or exceeds the pressure transition threshold, it is determined that the near-wall area of ​​the sealing surface has entered the gas phase depletion stage where the precursor gas concentration decreases, and the low collision cross-section area where the mean free path of ions increases in the gas phase deposition environment is identified. Step 105: During the gas phase depletion stage, an RF negative bias voltage with an amplitude of -300V to -600V is applied to the valve substrate to accelerate the ions generated by the plasma source through the low collision cross-section region, so that the ions impact the nuclei on the sealing surface with peak kinetic energy and induce dislocations inside the crystal of the reinforcement layer to block the longitudinal epitaxial growth of columnar crystals.

2. The vapor deposition process for strengthening valve sealing surfaces according to claim 1, characterized in that, In step 101, the heating control unit adjusts the heating power according to the real-time temperature signal collected by the thermocouple, so that the temperature fluctuation range of the valve substrate is within ±2℃; in step 105, the duty cycle of the radio frequency negative bias is set to 15% to 25%, and the total energy injection is determined by limiting the pulse width of ion bombardment, thereby constructing a residual compressive stress field inside the reinforcement layer.

3. The vapor deposition process for strengthening valve sealing surfaces according to claim 1, characterized in that, After the ion bombardment action in step 105 is completed, the process further includes: step 301, injecting high-purity argon carrier gas into the sealing surface area; step 302, using the adiabatic expansion process generated by the high-purity argon carrier gas in the sealing surface area to absorb the residual heat generated by the ion bombardment, and independently absorbing the transient enthalpy of the surface micro-region at the top of the nucleus germinating on the sealing surface through convection heat transfer, so that the transient local temperature of the sealing surface returns to within 450°C to 480°C.

4. The vapor deposition process for strengthening valve sealing surfaces according to claim 1, characterized in that, The precursor gas includes vapor containing a metal element and a reactant gas; the vapor containing a metal element is selected from chromium vapor, titanium vapor or aluminum vapor; the reactant gas is selected from nitrogen, methane or oxygen.

5. A vapor deposition process for strengthening valve sealing surfaces according to claim 1, characterized in that, In step 104, the pressure transition threshold is adjusted according to the flow rate of the precursor gas. When the flow rate of the precursor gas increases, the active gas rapidly replenished into the vacuum chamber produces a macroscopic backfilling effect in terms of fluid dynamics. This dynamic gas replenishment effectively offsets the sudden drop in local transient pressure caused by the consumption of precursor molecules by heterogeneous nucleation and crystallization at the sealing surface. As a result, the fluctuation rate of pressure drop in the microscopic closed flow field near the wall of the sealing surface, which is actually collected by the pressure monitoring unit, slows down, and the absolute value of the pressure transition threshold decreases accordingly.

6. The vapor deposition process for strengthening valve sealing surfaces according to claim 3, characterized in that, In step 301, the injection pressure of the high-purity argon carrier gas is 0.5 MPa to 1.2 MPa higher than the deposition pressure inside the vacuum chamber; the sealing surface is physically cleaned by the jet gas generated by the pressure gradient.

7. A vapor deposition process for strengthening valve sealing surfaces according to claim 1, characterized in that, The frequency of the radio frequency negative bias is set according to the transit time of ions through the low collision cross-section region, so that the acceleration path of the ions is synchronized with the pulse period of the radio frequency negative bias.

8. A vapor deposition process for strengthening valve sealing surfaces according to claim 1, characterized in that, In step 103, the pressure monitoring unit includes a piezoelectric thin film sensor disposed on the wall of the vacuum chamber; the piezoelectric thin film sensor captures pressure pulses near the wall and transmits the pressure signal to the control unit to calculate the transient pressure drop rate.

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