A wear-resistant coating for processing of titanium alloy materials and a processing technology thereof

Abstract

The application relates to the technical field of wear-resistant coating processing, in particular to a wear-resistant coating for processing titanium alloy materials and a processing technology thereof, which comprises the following steps: pretreating a tool base body for processing titanium alloy, coating deposition is carried out on the pretreated tool base body by using a plasma-enhanced chemical vapor deposition technology; a plasma sheath voltage, a radio frequency current, a deposition chamber pressure and a base body temperature in a coating deposition process are collected in real time; an optimal flow of various gas components at different coating thicknesses in the coating deposition process is obtained by using an optimization algorithm to construct a fitness function in the optimization algorithm, the construction of the fitness function comprises the following steps: determining a component gradient loss item and a transition smoothness loss item of the coating deposition; annealing treatment is carried out after the coating deposition reaches a set thickness, and then cooling to room temperature. The wear-resistant performance of the processed wear-resistant coating is improved.

Description

Technical Field

[0001] The present application relates to the technical field of wear-resistant coating processing, and in particular to a wear-resistant coating for processing titanium alloy materials and a processing technology thereof. Background Art

[0002] Titanium alloys are widely used in aerospace, high-end equipment manufacturing, medical devices, and other fields due to their high strength, low density, and excellent corrosion resistance. However, their low surface hardness and insufficient wear resistance make machining tools, such as carbide cutting tools, susceptible to adhesive wear and thermal damage during cutting. Tool life is only about half that of machining steel parts, necessitating wear-resistant coatings. A gradient coating is a functional coating in which the composition, structure, or properties of the coating material vary continuously or quasi-continuously through the thickness. Its core feature is the gradual transition of composition to eliminate distinct interfaces between different materials, thereby significantly reducing stress differences within the coating and between the coating and the substrate, thereby improving overall bonding strength and service performance.

[0003] Traditional physical vapor deposition (PVD) technology improves wear resistance by depositing hard coatings such as TiN and TiC to form gradient coatings. However, the preparation of gradient coatings relies on segmented adjustment of process parameters. The parameter adjustment interval is much larger than the diffusion scale of the coating components, resulting in sudden changes in the composition between adjacent layers and large differences in elastic modulus. During service, the coating is easily peeled off due to interface stress concentration.

[0004] Existing technology uses laser cladding technology to prepare refractory high-entropy alloy gradient coatings, but the high temperature during the cladding process causes the elements to diffuse violently, forming a mixed transition zone, and there are still microstructural mutations between adjacent cladding layers, and the existence of macroscopic interfaces cannot be avoided. The difference in thermal expansion coefficients between the coating and the titanium alloy substrate can easily cause interfacial thermal stress concentration when the temperature changes, exceeding the bonding strength of the coating and causing it to fall off.

[0005] In summary, in the preparation of wear-resistant coatings for titanium alloy processing, there is a problem of how to achieve continuous transition of the composition of the gradient coating and eliminate the physical interface to solve the problem of coating peeling failure caused by sudden composition change and interface stress concentration in traditional processes. Summary of the Invention

[0006] In order to solve the above technical problems, the purpose of this application is to provide a wear-resistant coating for titanium alloy material processing and a processing technology thereof. The technical solutions adopted are as follows:

[0007] In a first aspect, an embodiment of the present application provides a process for processing a wear-resistant coating for processing titanium alloy materials, the process comprising:

[0008] Pre-treating the tool substrate for processing titanium alloy, and depositing coating on the pre-treated tool substrate using plasma enhanced chemical vapor deposition technology;

[0009] Real-time collection of plasma sheath voltage, radio frequency current, deposition chamber pressure, and substrate temperature during the coating deposition process;

[0010] By constructing a fitness function in the optimization algorithm, the optimization algorithm is used to obtain the optimal flow rate of various gas components at different coating thicknesses during the coating deposition process. The construction of the fitness function includes:

[0011] Based on the differences between the optimized flow rates of various gas components at different coating thicknesses and the preset target flow rates and actual flow rates during the coating deposition process, the composition gradient loss term of the coating deposition is determined by combining the plasma sheath voltage, RF current, and deposition chamber pressure during optimization using the optimization algorithm.

[0012] Based on the differences in the optimized flow rates of various gas components at adjacent coating thicknesses during the coating deposition process and the substrate temperature during optimization, the transition smoothness loss term of the coating deposition is obtained.

[0013] Combining the component gradient loss term and the transition smoothness loss term to obtain a fitness function in the optimization algorithm;

[0014] After the coating is deposited to a set thickness, it is annealed and then cooled to room temperature.

[0015] In one embodiment, the pre-processing comprises:

[0016] Immerse the tool substrate in a mixture containing 10%~30% HF and 20%~40% In the electrolyte, a pulse current with a frequency of 5~10Hz and a peak current density of 1~3A / cm² is applied. The activation degree of the substrate surface is monitored by the volt-ampere characteristic curve. The pretreatment is terminated when the volt-ampere characteristic curve tends to be stable.

[0017] In one embodiment, the parameter range of the plasma enhanced chemical vapor deposition technology is:

[0018] The RF power is , the deposition chamber pressure is , the substrate temperature is , high purity argon Ar is used as carrier gas with a flow rate of 50~100sccm, and the titanium source is , heated to 50~70℃ by vaporizer, carried by carrier gas Ar with a flow rate of 1~5sccm; the carbon source is , nitrogen source is .

[0019] In one embodiment, the wear-resistant coating deposited by the coating includes a bottom layer and a surface layer, the bottom layer is a TiC-rich layer, the thickness of which accounts for 20% to 30%; the surface layer is a TiN-rich layer, the thickness of which accounts for 70% to 80%.

[0020] In one embodiment, when the bottom TiC-rich layer is deposited using plasma enhanced chemical vapor deposition technology, the control The flow rate is 15~20sccm, The flow rate is 10~15sccm and the bias voltage is -150 to -200V, forming a columnar crystal structure with a TiC content of 60%~80%;

[0021] When using plasma enhanced chemical vapor deposition technology to deposit the surface TiN enriched layer, control The flow rate is 5~10sccm, The flow rate is 20~30sccm, the bias voltage is -50 to -100V, and a dense film layer with a TiN content of 70%~90% is formed.

[0022] In one embodiment, the expression of the component gradient loss term is:

[0023] , where is the composition gradient loss term of coating deposition, 、 and They represent the plasma sheath voltage, RF current and deposition chamber pressure collected at the beginning of each optimization, Z represents the layer of the current coating thickness, and J represents the type of gas component controlled during the deposition process using PECVD technology. represents the optimized flow rate of the jth gas component when the coating thickness level is z, is the actual flow rate of the jth gas component when the coating thickness level is z, It represents the target flow rate of the jth gas component when the coating thickness level is z, wherein the level is the sequence number obtained by evenly dividing the set thickness of the coating into intervals and arranging the intervals in ascending order.

[0024] In one embodiment, the transition smoothness loss term is expressed as:

[0025] , where is the transition smoothness loss term of coating deposition, exp() is an exponential function with a natural constant as the base, represents the coating thickness interval of each layer, T represents the substrate temperature collected each time the optimization starts, Indicates the preset maximum temperature. is the optimized flow rate of the jth gas component when the coating thickness level is z-1.

[0026] In one embodiment, the fitness function in the optimization algorithm is the sum of the component gradient loss term and the transition smoothness loss term, and the optimization goal is to minimize the fitness function.

[0027] In one embodiment, the annealing treatment uses pulsed direct current with a current density of 5-10 A / cm², a pulse width of 10-50 ms, and an annealing time of 1-5 min.

[0028] In a second aspect, an embodiment of the present application further provides a wear-resistant coating for processing titanium alloy materials, wherein the wear-resistant coating for processing titanium alloy materials is produced by using any of the processing techniques for processing titanium alloy materials described above.

[0029] This application has at least the following beneficial effects:

[0030] The present application pre-treats the tool substrate for processing titanium alloys, and uses plasma enhanced chemical vapor deposition technology to deposit a coating on the pre-treated tool substrate; the pre-treatment avoids the risk of coating peeling due to interface contamination, and improves the bonding strength between the coating and the titanium alloy substrate; the plasma sheath voltage, radio frequency current, deposition chamber pressure, and substrate temperature during the coating deposition process are collected in real time; the controllability and stability of the process are enhanced by real-time monitoring of multiple parameters; the fitness function in the optimization algorithm is constructed, and the optimal flow rate of various gas components at different coating thicknesses during the coating deposition process is obtained by the optimization algorithm. The construction of the fitness function includes: based on the coating deposition The composition gradient loss term of coating deposition is determined by combining the differences between the optimized flow rates of various gas components at different coating thicknesses, the preset target flow rates, and the actual flow rates with the plasma sheath voltage, RF current, and deposition chamber pressure during optimization by the optimization algorithm. The transition smoothness loss term of coating deposition is derived based on the differences between the optimized flow rates of various gas components at adjacent coating thicknesses during coating deposition and the substrate temperature during optimization by the optimization algorithm. The fitness function in the optimization algorithm is derived by combining the composition gradient loss term and the transition smoothness loss term. The fitness function constructed based on the composition gradient loss term and the transition smoothness loss term enables precise control of the gradient of coating composition and structure. Dynamically adjusting the gas flow rate through the optimization algorithm ensures that the chemical gradient of coatings of different thicknesses meets the design requirements, avoiding the interface brittleness problem caused by compositional mutations in traditional fixed-flow processes. The introduction of the transition smoothness loss term further suppresses interlayer stress concentration and improves the fatigue resistance of the coating under cyclic load; at the same time, combined with gas flow optimization and dynamic matching of plasma parameters, the structural continuity of the coating from the substrate to the surface is improved, forming a gradient hardness distribution, which not only ensures the wear resistance of the surface, but also alleviates the stress mismatch between the hard coating and the tough substrate through the flexible intermediate layer, avoiding the early peeling of the single-component coating due to excessive hardness difference; after the coating deposition reaches the set thickness, it is annealed and then cooled to room temperature, which ultimately increases the service life of the coating and enhances the wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 A flowchart of the steps of a processing process for a wear-resistant coating for titanium alloy material processing provided in one embodiment of the present application;

[0033] Figure 2 Construct a flow graph for the fitness function. DETAILED DESCRIPTION

[0034] To further illustrate the technical means and effects employed by this application to achieve the intended invention objectives, the following, in conjunction with the accompanying drawings and preferred embodiments, details the wear-resistant coating for titanium alloy material processing and its processing technology, as well as its specific implementation, structure, features, and effects. In the following description, different references to "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0035] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0036] The specific scheme of a wear-resistant coating for titanium alloy material processing and its processing technology provided by the present application is described in detail below with reference to the accompanying drawings.

[0037] Example 1

[0038] See also Figure 1 , which shows a flowchart of the steps of a processing process for a wear-resistant coating for titanium alloy material processing provided in Example 1 of the present application, the process includes:

[0039] S1, pre-treating a tool substrate for processing titanium alloy, and depositing a coating on the pre-treated tool substrate using plasma enhanced chemical vapor deposition technology.

[0040] Wear-resistant coatings are applied to the surface of titanium alloy processing tools, including carbide tools, CBN grinding wheels, ceramic milling cutters, diamond-coated molds, etc., to improve the wear resistance of tools when cutting and grinding titanium alloy materials. The tool substrate selected in this embodiment is carbide, and the implementer can choose other tool substrates at will. The wear-resistant coating processed in this embodiment includes a bottom layer and a surface layer, wherein the bottom layer is a TiC-enriched layer with a thickness of 20% to 30%, which is used to enhance the metallurgical bonding with the tool substrate; the surface layer is a TiN-enriched layer with a thickness of 70% to 80%, which is used to reduce the friction coefficient and improve anti-adhesion. The bottom layer and the surface layer are connected by a composition gradient transition zone with a thickness of 50 to 200 nm.

[0041] Titanium alloy tooling often has an oxide layer on its substrate, hindering the metallurgical bonding between the coating and the substrate. Electrochemical activation involves an electrochemical reaction between the electrolyte and the oxide layer on the substrate surface, effectively removing the oxide layer and exposing a fresh metal surface. During electrochemical activation, a micron-scale roughened interface forms on the substrate surface, significantly improving coating adhesion and bonding strength through a mechanical locking effect.

[0042] Therefore, the tool substrate for machining titanium alloy is pretreated by electrochemical activation, specifically: the tool substrate is immersed in a solution containing 10% HF and 20% In the electrolyte, a pulse current with a frequency of 5Hz and a peak current density of 1A / cm² is applied, and the activation degree of the substrate surface is monitored by the volt-ampere characteristic curve. The pretreatment is terminated when the volt-ampere characteristic curve tends to be stable. The pulse current is periodically turned on and off, which promotes the dissolution of the oxide layer during the power-on period and allows the ions in the electrolyte to diffuse and replenish during the power-off period, thereby avoiding local electrolyte 、 Plasma depletion and the suppression of side reactions, such as hydrogen evolution reactions, effectively avoid excessive corrosion pits caused by direct current. When monitoring the degree of substrate surface activation using the voltammetric characteristic curve, a three-electrode system is used: the substrate to be activated is the working electrode, the reference electrode is a saturated calomel electrode (SCE), and the counter electrode is a platinum sheet. Linear sweep voltammetry is performed on an electrochemical workstation at a scan rate of 5 mV / s over a potential range covering the substrate redox reaction range of -0.5 V to 1.5 V vs. SCE.

[0043] Plasma-enhanced chemical vapor deposition (PECVD) dissociates reactive gases through plasma discharge, generating highly active ions, atoms, and free radicals. These active particles can bombard the substrate surface, remove contaminants, and form a microscopic rough structure. At the same time, they chemically bond with atoms on the substrate surface, significantly improving the interfacial bonding strength between the coating and the substrate and preventing coating peeling.

[0044] PECVD technology deposits coatings at relatively low temperatures, avoiding the damage to substrate strength, toughness, and surface finish caused by high temperatures. It is particularly suitable for temperature-sensitive precision machining tools. Titanium alloy machining tools often have complex curved surfaces, grooves, or micropores on their surfaces. PECVD's plasma has excellent uniformity, and the deposition process offers a certain degree of wraparound plating capability. This allows for the formation of uniformly thick, dense, and defect-free coatings on irregular surfaces, avoiding the blind spots of traditional physical vapor deposition (PVD) in deep holes and grooves.

[0045] Based on the above analysis, this embodiment uses PECVD technology to deposit a wear-resistant coating on the surface of the pre-treated tool substrate. The power supply used in this embodiment is a 13.56MHz RF power supply that supports pulse mode and a duty cycle of 50% to control the plasma density and energy. The deposition chamber is a cylindrical vacuum chamber with a volume of 50L and an inner wall plating Anti-corrosion coating.

[0046] The gas supply of the PECVD technology in this embodiment is as follows: carrier gas: high-purity argon Ar, with a flow rate of 50 sccm; titanium source: , heated to 50°C by a vaporizer and carried by carrier gas Ar with a flow rate of 1 sccm; carbon source: , providing C atoms to form TiC; nitrogen source: , providing N atoms to form TiN.

[0047] The parameter range of the PECVD technology in this embodiment is set to: RF power S is , the deposition chamber pressure P is , the substrate temperature T is .

[0048] The specific steps of PECVD technology to deposit wear-resistant coating on the surface of tool substrate are:

[0049] Fix the pre-treated tool substrate on the sample stage of the PECVD equipment; reduce the vacuum degree of the deposition chamber to , to prevent air impurities from affecting the coating quality; introduce inert gas Ar, and at the same time apply radio frequency power to excite plasma, using ions to bombard the substrate surface to further remove residual contaminants and activate the surface. The duration of introducing inert gas Ar is 5 minutes;

[0050] When using PECVD technology to deposit the bottom TiC-rich layer, control The target flow rate is 15 sccm, The target flow rate is 10 sccm and the bias voltage is -150 to -200 V, forming a columnar crystal structure with a TiC content of 60% to 80%;

[0051] When using PECVD technology to deposit the surface TiN enriched layer, control The target flow rate is 5 sccm, The target flow rate is 20 sccm and the bias voltage is -50 to -100 V, forming a dense film with a TiN content of 70% to 90%.

[0052] S2, real-time collection of plasma sheath voltage, RF current, deposition chamber pressure, and substrate temperature during the coating deposition process.

[0053] During the deposition process using PECVD technology, sensors are used to collect the electrical and thermodynamic parameters of the plasma in real time. The collected electrical and thermodynamic parameters include the plasma sheath voltage Vp, RF current Ip, deposition chamber pressure P, substrate temperature T, and coating deposition rate R. The specific collection process is as follows:

[0054] (1) Plasma sheath voltage Vp: The plasma sheath voltage Vp is collected non-invasively by a Langmuir probe. The probe is placed parallel to the substrate surface, 5 mm away from the deposition area, and sampled in real time at a frequency of 1 kHz.

[0055] The sheath voltage directly determines the kinetic energy of plasma ions bombarding the substrate surface, affecting the coating-substrate bonding, coating density, and surface roughness. When Vp is too low, insufficient ion energy results in weak coating adhesion; excessive Vp can cause excessive sputtering on the substrate surface, damaging the coating structure. By monitoring Vp in real time, the RF power or bias voltage can be dynamically adjusted to match the ion energy to the bonding requirements between the substrate and coating material.

[0056] RF current Ip: A high-frequency current transformer is connected to the transmission cable from the RF power supply to the deposition electrode, and is sampled in real time at a frequency of 1 kHz.

[0057] The RF current is positively correlated with the degree of plasma ionization. The larger the Ip, the higher the plasma density and the more likely the particles will be deposited. 、 The higher the concentration, the more directly it affects the deposition rate and coating composition uniformity. In the preparation of gradient composition coatings, it is necessary to control the ratio of metal ions to carbon and nitrogen ions by adjusting Ip to avoid composition deviations that lead to a decrease in the hardness or wear resistance of the wear-resistant coating.

[0058] Deposition chamber pressure P: A capacitive thin film vacuum gauge is directly installed on the side wall of the deposition chamber and samples are taken in real time at a frequency of 50 Hz.

[0059] The deposition chamber pressure determines the mean free path and collision frequency of gas molecules, affecting plasma distribution uniformity and the efficiency of reactant gas dissociation. At low pressures, ions migrate over long distances, facilitating targeted bombardment and suitable for producing dense coatings. At high pressures, particle collisions are frequent, resulting in faster deposition rates but potentially looser coating structures. Pressure feedback allows for dynamic adjustment of the inlet gas flow rate to balance deposition rate and coating density.

[0060] Base temperature T: K-type thermocouple is embedded on the back of the tool base, and the distance between the thermocouple temperature measuring end and the base surface is 0.5mm, real-time sampling at 10Hz frequency.

[0061] Substrate temperature influences the diffusion of atoms on the substrate surface, determining the coating's crystal form, grain size, and internal stress. At low temperatures, atomic diffusion is limited, leading to an amorphous or nanocrystalline coating structure, resulting in high hardness but high internal stress. At high temperatures, grain coarsening reduces internal stress but may soften the substrate. By controlling substrate temperature, the balance between coating toughness and hardness can be optimized.

[0062] Coating deposition rate R: Monitored by a quartz crystal microbalance, the quartz crystal oscillator is mounted on the same plane as the tool substrate, and the crystal oscillator frequency offset is measured. , according to the crystal oscillator frequency offset Calculate the deposition mass rate, combined with the coating material density , where the density of TiN is 5.22g / cm³ and the density of TiC is 4.93g / cm³, which is converted to the deposition rate , where A represents the crystal oscillator area, N represents the quartz crystal constant, which is 17.7Hz・cm² / ng in this embodiment, and the crystal oscillator frequency offset is Real-time sampling at 1Hz frequency.

[0063] The deposition rate directly determines the coating growth dynamics and is a key parameter for achieving the target coating thickness, especially in multilayer composite coatings where the thickness ratio must be controlled layer by layer. Real-time monitoring of the deposition rate, R, using a quartz crystal microbalance combined with deposition time allows for precise control of the thickness of each layer, avoiding uneven coating thickness caused by rate fluctuations.

[0064] It should be noted that, to facilitate subsequent analysis, this embodiment uses multi-source sensor synchronization technology to output PPS pulse signals through the GNSS system for time synchronization, marks data points through timestamps, and uses linear interpolation to synchronize low-frequency signals to high-frequency time series to ensure the time alignment of the electrical parameters and thermodynamic parameters collected in this embodiment.

[0065] S3, by constructing the fitness function in the optimization algorithm, the optimization algorithm is used to obtain the optimal flow rate of various gas components at different coating thicknesses during the coating deposition process.

[0066] Furthermore, in this embodiment, the optimization algorithm adopts a particle swarm optimization algorithm, which iteratively searches for the optimal PECVD process parameter combination and dynamically adjusts the PECVD process parameters to form a nanocomposite coating with a gradient structure.

[0067] When preparing gradient coatings, it is expected that the coating components will exhibit a specific gradient distribution in the thickness direction. However, the actual deposition process is affected by fluctuations in PECVD process parameters, which can cause the actual coating component distribution to deviate from the target gradient. Instability in the plasma sheath voltage may affect the energy and trajectory of ions, thereby changing the incorporation ratio of atoms in the coating; changes in the RF current will affect the density and activity of the plasma, causing changes in the concentration and reaction rate of the reactive particles; and fluctuations in the deposition chamber pressure will affect the mean free path of gas molecules and the collision frequency of particles, interfering with the transport and deposition of atoms.

[0068] S3.1, based on the differences between the optimized flow rates of various gas components at different coating thicknesses during the coating deposition process and the preset target flow rates and actual flow rates, combined with the plasma sheath voltage, RF current, and deposition chamber pressure during optimization by the optimization algorithm, determine the component gradient loss term of the coating deposition.

[0069] Therefore, there is often a difference between the actual coating composition and the target gradient composition. This embodiment quantifies this deviation through the composition gradient loss term. By minimizing the composition gradient loss term, the coating composition is continuously distributed, avoiding the formation of physical interfaces that cause coating stress concentration. Since different tool substrates require different total coating thicknesses, in this embodiment, the total coating thickness is set to 2μm. The total coating thickness is discretized, that is, the total coating thickness is composed of multiple layers. In this embodiment, the coating thickness of each layer is set to 50nm. When the coating thickness is between 0 and 50nm, the corresponding level is 1, when the coating thickness is between 51 and 100nm, the corresponding level is 2, and when the coating thickness is between 101 and 150nm, the corresponding level is 3. Accordingly, the level corresponding to the coating thickness in each interval before the coating thickness of the tool substrate reaches the total coating thickness can be obtained. That is, the total coating thickness is evenly divided into intervals at intervals of 50nm, and the level is the serial number after each interval is arranged in ascending order. Among them, the coating deposition thickness can be obtained by integrating the coating deposition rate R with the deposition time t.

[0070] In this embodiment, the component gradient loss term The calculation formula is: , where is the composition gradient loss term of coating deposition, 、 and They represent the plasma sheath voltage, RF current and deposition chamber pressure collected at the beginning of each optimization, Z represents the layer of the current coating thickness, and J represents the type of gas component controlled during the deposition process using PECVD technology. In this embodiment, J=2, and the gas components include and Two categories, represents the optimized flow rate of the jth gas component when the coating thickness level is z, is the actual flow rate of the jth gas component when the coating thickness level is z, represents the target flow rate of the jth gas component when the coating thickness level is z. When the particle swarm optimization algorithm is used for optimization, the optimal flow rate of each gas component is obtained when the current coating thickness level is reached. This reflects the difference between the optimized flow rates of various gas components at different coating thicknesses and the preset target flow rates. The difference represents the degree of difference between two variables and can be calculated using methods such as the difference, the absolute value of the difference, the square of the difference, or a ratio, which are not limited in this embodiment. The actual flow rates of the gas components can be obtained from the gas introduction equipment during the coating deposition process.

[0071] During the coating deposition process, the gas flow rate is the direct precursor parameter that determines the coating composition. By minimizing the composition gradient loss term, the deposited coating composition can be made close to the gradient coating, and the weight is determined based on the collected electrical parameters and thermodynamic parameters. The larger the Vp, the higher the plasma energy and the stronger the controllability of the coating composition deposition. At this time, the deviation between the gas flow rate and the target flow rate should be more strictly penalized; the larger the Ip, the higher the plasma density. The product of Vp and Ip represents the activity level of the plasma. The higher the activity level, the greater the penalty weight for gas flow deviation. The smaller P is, the less collision interference the deposition process is, and the coating composition distribution is easier to control, so the weight is The larger the value, the more severe the penalty for gas flow deviation at low deposition chamber pressure. The larger it is, the greater the contribution of the component gradient loss term in the optimization algorithm will be when the optimization algorithm is used later, causing the parameter update direction to point more strongly to the direction of reducing the component gradient loss term.

[0072] S3.2, based on the difference in the optimized flow rates of various gas components at adjacent coating thicknesses during the coating deposition process, combined with the substrate temperature during optimization by the optimization algorithm, the transition smoothness loss term of the coating deposition is obtained.

[0073] The composition gradient loss term indirectly measures the composition change between adjacent layers of the coating by the deviation between the introduced gas flow rate and the target flow rate, but does not take into account the interface formation tendency caused by the influence of temperature on diffusion. Although it can ensure the basic continuity of the composition gradient, it is also necessary to quantify the effective gradient penalty under actual process conditions to avoid interface mutations caused by differences in the spacing between adjacent layers of the coating or non-uniform diffusion caused by temperature.

[0074] Therefore, this embodiment takes into account the interface formation tendency caused by temperature influence diffusion and constructs the transition smoothness loss term , the calculation formula is: , where is the transition smoothness loss term of coating deposition, exp() is an exponential function with a natural constant as the base, and according to the coating thickness discretization method in the composition gradient loss term, Indicates the coating thickness interval of each layer. In this embodiment , used to normalize the spatial scale of component changes so that the gradient calculation is related to the actual physical distance; T represents the matrix temperature collected at the beginning of each optimization, Indicates the maximum temperature. In this embodiment , avoid excessive temperature, is the optimized flow rate of the jth gas component when the coating thickness level is z-1. It reflects the difference in the optimized flow rate of various gas components at adjacent coating thicknesses in order to avoid excessive fluctuations in gas flow rate.

[0075] It should be understood that the more drastic the composition change between adjacent layers of the coating, the easier it is to form a clear interface. Therefore, it is necessary to quantify the composition gradient. By minimizing the transition smoothness loss term, the composition change between adjacent layers of the coating can be reduced to avoid the formation of an interface. The weight is determined based on the substrate temperature, and an exponential function is introduced to perform differentiated constraints on the coating composition change at different temperatures. The higher the temperature, the stronger the atomic diffusion ability, and the weight is reduced, allowing a certain degree of coating composition change; the lower the temperature, the weaker the atomic diffusion ability, and the weight is increased. The coating composition change needs to be more strictly controlled to avoid interface mutations caused by insufficient atomic diffusion at low temperatures.

[0076] S3.3, combining the component gradient loss term and the transition smoothness loss term to obtain a fitness function in the particle swarm optimization algorithm.

[0077] Specifically, this embodiment uses particle swarm optimization algorithm to optimize the process of depositing coating using PECVD technology. Traffic and Traffic, first of all, is based on Traffic and The flow rate setting interval range randomly generates 30 particles, which are expressed as , represents the vector representation of the i-th particle, is the i-th particle flow, is the i-th particle The flow rate, the initial position and velocity of the particles are evenly distributed. When the bottom TiC-rich layer is deposited using PECVD technology, The flow rate setting range is 15~20sccm, The flow rate setting range is 10~15sccm; when using PECVD technology to deposit the surface TiN enriched layer, The flow rate setting range is 5~10sccm, The flow rate setting range is 20~30sccm.

[0078] Fitness function of particle swarm optimization algorithm Set to By minimizing the fitness function, we can find the optimal solution and obtain the best performance in the process of coating deposition using PECVD technology. Traffic and The iterative termination condition is the fitness change of the global optimal value after 10 consecutive iterations. , or when the maximum number of iterations is reached, the iteration is terminated. In this embodiment, the maximum number of iterations is set to 50 times. The implementer can set it according to the actual situation. This embodiment does not limit it. The fitness function construction flow chart is as follows Figure 2 shown.

[0079] It should be noted that, in this embodiment, every time a coating with a thickness of 50 nm is deposited, the iterative optimization of the particle swarm optimization algorithm is triggered, and the number of layers in the process of depositing the coating is updated. Traffic and Flow rate, to ensure the composition accuracy of the gradient coating, that is, the coating thickness is measured once each layer is reached. Traffic and Flow optimization: The iterative optimization of the particle swarm optimization algorithm is a well-known technology, which will not be described in detail in this embodiment. The implementer can choose other feasible optimization algorithms, such as genetic algorithms, etc.

[0080] S4, after the coating is deposited to a set thickness, it is annealed and then cooled to room temperature.

[0081] During the plasma-enhanced chemical vapor deposition (PECVD) process, coatings are bombarded with high-energy particles and rapidly cooled, which can easily lead to structural defects such as lattice distortion and dislocation accumulation, resulting in internal stress. Furthermore, the precipitation of hard phases such as TiC and TiN can be unevenly distributed or coarse. Annealing, by applying a pulsed current and utilizing the Joule heating effect to rapidly heat the coating, eliminates internal stress, promotes homogenization of the hard phase, and improves interfacial bonding.

[0082] The current-induced localized metallurgical reaction enhances atomic diffusion between the coating and the tool substrate, improving bonding strength and effectively addressing the problem of coating shedding caused by high loads and high temperatures during titanium alloy machining. Pulsed current annealing not only avoids the effects of traditional high-temperature annealing on the mechanical properties of the substrate, but also achieves targeted optimization of the coating microstructure through precise energy control.

[0083] Therefore, the annealing treatment in this embodiment adopts pulsed direct current with a current density of 5A / cm², a pulse width of 10ms, and an annealing time of 1min to eliminate the internal stress of the coating and promote the uniform distribution of the TiC / TiN hard phase.

[0084] The coating is rapidly annealed by utilizing the Joule heating effect and electromagnetic effect of the pulse current. When the pulse current passes through the coating, the resistance heat causes the coating to heat up locally, promoting the precipitation and uniform distribution of the TiC / TiN hard phase and eliminating the residual stress inside the coating. The alternating magnetic field generated by the pulse current can refine the grains and inhibit harmful phases such as The generation of ions improves the density of the coating.

[0085] In pulsed current annealing, the coating surface acts as the anode and the tool substrate acts as the cathode, forming a closed current loop. Current primarily flows through the coating area, achieving targeted heating. In this embodiment, the pulsed current annealing process involves clamping the coated workpiece in a pulsed current device. A pulsed direct current is applied, with the positive electrode connected to the coating surface and the negative electrode connected to the tool substrate. Annealing is then performed according to the previously defined parameters. After annealing, the workpiece is cooled naturally to room temperature, completing the wear-resistant coating for titanium alloy machining.

[0086] Example 2

[0087] See also Figure 1 , which shows a flowchart of the steps of a processing process for a wear-resistant coating for titanium alloy material processing provided in Example 2 of the present application, the process comprising:

[0088] Wear-resistant coatings are applied to the surface of titanium alloy processing tools, including carbide tools, CBN grinding wheels, ceramic milling cutters, diamond-coated molds, etc., to improve the wear resistance of tools when cutting and grinding titanium alloy materials. The tool substrate selected in this embodiment is carbide, and the implementer can choose other tool substrates at will. The wear-resistant coating processed in this embodiment includes a bottom layer and a surface layer, wherein the bottom layer is a TiC-enriched layer with a thickness of 20% to 30%, which is used to enhance the metallurgical bonding with the tool substrate; the surface layer is a TiN-enriched layer with a thickness of 70% to 80%, which is used to reduce the friction coefficient and improve anti-adhesion. The bottom layer and the surface layer are connected by a composition gradient transition zone with a thickness of 50 to 200 nm.

[0089] Titanium alloy tooling often has an oxide layer on its substrate, hindering the metallurgical bonding between the coating and the substrate. Electrochemical activation involves an electrochemical reaction between the electrolyte and the oxide layer on the substrate surface, effectively removing the oxide layer and exposing a fresh metal surface. During electrochemical activation, a micron-scale roughened interface forms on the substrate surface, significantly improving coating adhesion and bonding strength through a mechanical locking effect.

[0090] Therefore, the tool substrate for machining titanium alloy is pretreated by electrochemical activation, specifically: the tool substrate is immersed in a solution containing 20% ​​HF and 30% In the electrolyte, a pulse current with a frequency of 8Hz and a peak current density of 2A / cm² is applied, and the activation degree of the substrate surface is monitored by the volt-ampere characteristic curve. The pretreatment is terminated when the volt-ampere characteristic curve tends to be stable. The pulse current is periodically turned on and off, which promotes the dissolution of the oxide layer during the power-on period and allows the ions in the electrolyte to diffuse and replenish during the power-off period, thereby avoiding local electrolyte 、 Plasma depletion and the suppression of side reactions, such as hydrogen evolution reactions, effectively avoid excessive corrosion pits caused by direct current. When monitoring the degree of substrate surface activation using the voltammetric characteristic curve, a three-electrode system is used: the substrate to be activated is the working electrode, the reference electrode is a saturated calomel electrode (SCE), and the counter electrode is a platinum sheet. Linear sweep voltammetry is performed on an electrochemical workstation at a scan rate of 13 mV / s over a potential range covering the substrate redox reaction range of -0.5 V to 1.5 V vs. SCE.

[0091] Plasma-enhanced chemical vapor deposition (PECVD) dissociates reactive gases through plasma discharge, generating highly active ions, atoms, and free radicals. These active particles can bombard the substrate surface, remove contaminants, and form a microscopic rough structure. At the same time, they chemically bond with atoms on the substrate surface, significantly improving the interfacial bonding strength between the coating and the substrate and preventing coating peeling.

[0092] PECVD technology deposits coatings at relatively low temperatures, avoiding the damage to substrate strength, toughness, and surface finish caused by high temperatures. It is particularly suitable for temperature-sensitive precision machining tools. Titanium alloy machining tools often have complex curved surfaces, grooves, or micropores on their surfaces. PECVD's plasma has excellent uniformity, and the deposition process offers a certain degree of wraparound plating capability. This allows for the formation of uniformly thick, dense, and defect-free coatings on irregular surfaces, avoiding the blind spots of traditional physical vapor deposition (PVD) in deep holes and grooves.

[0093] Based on the above analysis, this embodiment uses PECVD technology to deposit a wear-resistant coating on the surface of the pre-treated tool substrate. The power supply used in this embodiment is a 13.56MHz RF power supply that supports pulse mode and a duty cycle of 70% to control the plasma density and energy. The deposition chamber is a cylindrical vacuum chamber with a volume of 80L and an inner wall plating Anti-corrosion coating.

[0094] The gas supply of the PECVD technology in this embodiment is as follows: carrier gas: high-purity argon Ar, with a flow rate of 80 sccm; titanium source: , heated to 60°C by a vaporizer and carried by carrier gas Ar with a flow rate of 3 sccm; carbon source: , providing C atoms to form TiC; nitrogen source: , providing N atoms to form TiN.

[0095] The parameter range of the PECVD technology in this embodiment is set to: RF power S is , the deposition chamber pressure P is , the substrate temperature T is .

[0096] The specific steps of PECVD technology to deposit wear-resistant coating on the surface of tool substrate are:

[0097] Fix the pre-treated tool substrate on the sample stage of the PECVD equipment; reduce the vacuum degree of the deposition chamber to , to prevent air impurities from affecting the coating quality; inert gas Ar is introduced, and at the same time, radio frequency power is applied to excite plasma, and ions are used to bombard the substrate surface to further remove residual pollutants and activate the surface. The duration of the inert gas Ar is 10 minutes.

[0098] When using PECVD technology to deposit the bottom TiC-rich layer, control The target flow rate is 18 sccm, The target flow rate is 13 sccm and the bias voltage is -150 to -200 V, forming a columnar crystal structure with a TiC content of 60% to 80%;

[0099] When using PECVD technology to deposit the surface TiN enriched layer, control The target flow rate is 8 sccm, The target flow rate is 25 sccm and the bias voltage is -50 to -100 V, forming a dense film with a TiN content of 70% to 90%.

[0100] The remaining steps are the same as those in Example 1 of the present application, except that during the annealing process, the current density is 8 A / cm², the pulse width is 30 ms, and the annealing time is 3 min.

[0101] Example 3

[0102] See also Figure 1 , which shows a flowchart of the steps of a processing process for a wear-resistant coating for titanium alloy material processing provided in Example 3 of the present application, the process comprising:

[0103] Wear-resistant coatings are applied to the surface of titanium alloy processing tools, including carbide tools, CBN grinding wheels, ceramic milling cutters, diamond-coated molds, etc., to improve the wear resistance of tools when cutting and grinding titanium alloy materials. The tool substrate selected in this embodiment is carbide, and the implementer can choose other tool substrates at will. The wear-resistant coating processed in this embodiment includes a bottom layer and a surface layer, wherein the bottom layer is a TiC-enriched layer with a thickness of 20% to 30%, which is used to enhance the metallurgical bonding with the tool substrate; the surface layer is a TiN-enriched layer with a thickness of 70% to 80%, which is used to reduce the friction coefficient and improve anti-adhesion. The bottom layer and the surface layer are connected by a composition gradient transition zone with a thickness of 50 to 200 nm.

[0104] Titanium alloy tooling often has an oxide layer on its substrate, hindering the metallurgical bonding between the coating and the substrate. Electrochemical activation involves an electrochemical reaction between the electrolyte and the oxide layer on the substrate surface, effectively removing the oxide layer and exposing a fresh metal surface. During electrochemical activation, a micron-scale roughened interface forms on the substrate surface, significantly improving coating adhesion and bonding strength through a mechanical locking effect.

[0105] Therefore, the tool substrate for machining titanium alloy is pretreated by electrochemical activation, specifically: the tool substrate is immersed in a solution containing 30% HF and 40% In the electrolyte, a pulse current with a frequency of 10Hz and a peak current density of 3A / cm² is applied, and the activation degree of the substrate surface is monitored by the volt-ampere characteristic curve. The pretreatment is terminated when the volt-ampere characteristic curve tends to be stable. The pulse current is periodically turned on and off, which promotes the dissolution of the oxide layer during the power-on period and allows the ions in the electrolyte to diffuse and replenish during the power-off period, thereby avoiding local electrolyte 、 Plasma depletion and the suppression of side reactions, such as hydrogen evolution reactions, effectively avoid excessive corrosion pits caused by direct current. When monitoring the degree of substrate surface activation using the voltammetric characteristic curve, a three-electrode system is used: the substrate to be activated is the working electrode, the reference electrode is a saturated calomel electrode (SCE), and the counter electrode is a platinum sheet. Linear sweep voltammetry is performed on an electrochemical workstation at a scan rate of 20 mV / s over a potential range covering the substrate redox reaction range of -0.5 V to 1.5 V vs. SCE.

[0106] Plasma-enhanced chemical vapor deposition (PECVD) dissociates reactive gases through plasma discharge, generating highly active ions, atoms, and free radicals. These active particles can bombard the substrate surface, remove contaminants, and form a microscopic rough structure. At the same time, they chemically bond with atoms on the substrate surface, significantly improving the interfacial bonding strength between the coating and the substrate and preventing coating peeling.

[0107] PECVD technology deposits coatings at relatively low temperatures, avoiding the damage to substrate strength, toughness, and surface finish caused by high temperatures. It is particularly suitable for temperature-sensitive precision machining tools. Titanium alloy machining tools often have complex curved surfaces, grooves, or micropores on their surfaces. PECVD's plasma has excellent uniformity, and the deposition process offers a certain degree of wraparound plating capability. This allows for the formation of uniformly thick, dense, and defect-free coatings on irregular surfaces, avoiding the blind spots of traditional physical vapor deposition (PVD) in deep holes and grooves.

[0108] Based on the above analysis, this embodiment uses PECVD technology to deposit a wear-resistant coating on the surface of the pre-treated tool substrate. The power supply used in this embodiment is a 13.56MHz RF power supply that supports pulse mode and a duty cycle of 80% to control the plasma density and energy. The deposition chamber is a cylindrical vacuum chamber with a volume of 100L and an inner wall plating volume of 100L. Anti-corrosion coating.

[0109] The gas supply of the PECVD technology in this embodiment is as follows: carrier gas: high-purity argon gas Ar, with a flow rate of 100 sccm; titanium source: , heated to 70°C by a vaporizer and carried by carrier gas Ar with a flow rate of 5 sccm; carbon source: , providing C atoms to form TiC; nitrogen source: , providing N atoms to form TiN.

[0110] The parameter range of the PECVD technology in this embodiment is set to: RF power S is , the deposition chamber pressure P is , the substrate temperature T is .

[0111] The specific steps of PECVD technology to deposit wear-resistant coating on the surface of tool substrate are:

[0112] Fix the pre-treated tool substrate on the sample stage of the PECVD equipment; reduce the vacuum degree of the deposition chamber to , to prevent air impurities from affecting the coating quality; inert gas Ar is introduced, and at the same time, radio frequency power is applied to excite plasma, and ions are used to bombard the substrate surface to further remove residual contaminants and activate the surface. The duration of the inert gas Ar is 15 minutes.

[0113] When using PECVD technology to deposit the bottom TiC-rich layer, control The target flow rate is 20 sccm, The target flow rate is 15 sccm and the bias voltage is -150 to -200 V, forming a columnar crystal structure with a TiC content of 60% to 80%;

[0114] When using PECVD technology to deposit the surface TiN enriched layer, control The target flow rate is 10 sccm, The target flow rate is 30 sccm and the bias voltage is -50 to -100 V, forming a dense film with a TiN content of 70% to 90%.

[0115] The remaining steps are the same as those in Example 1 of the present application, except that during the annealing process, the current density is 10 A / cm², the pulse width is 50 ms, and the annealing time is 5 min.

[0116] Comparative Example 1

[0117] In Comparative Example 1, the same steps and parameters as those in Example 1 of the present application are followed, except that during the coating deposition process using PECVD technology, the gas flow rate is not optimized or updated, and the gas flow rate remains the same as the set target flow rate to prepare a wear-resistant coating for titanium alloy material processing.

[0118] Comparative Example 2

[0119] In Comparative Example 2, the same steps and parameters as those in Example 2 of the present application are followed, except that during the coating deposition process using PECVD technology, the gas flow rate is not optimized or updated, and the gas flow rate remains the same as the set target flow rate to prepare a wear-resistant coating for titanium alloy material processing.

[0120] Comparative Example 3

[0121] In Comparative Example 3, the same steps and parameters as those in Example 3 of the present application are followed, except that during the coating deposition process using PECVD technology, the gas flow rate is not optimized or updated, and the gas flow rate remains the same as the set target flow rate to prepare a wear-resistant coating for titanium alloy material processing.

[0122] The performance comparison results of the wear-resistant coatings of the examples of the present application and the comparative examples are shown in Table 1.

[0123] Table 1 Performance comparison results of wear-resistant coatings of the embodiment and the comparative example

[0124]

[0125] It can be seen from Table 1 that the processing performance of the final wear-resistant coating can be significantly improved by optimizing the gas flow rate during the coating deposition process of the PECVD technology.

[0126] Based on the same inventive concept as the above method, an embodiment of the present application also provides a wear-resistant coating for processing titanium alloy materials, and the wear-resistant coating is produced by any one of the processing processes described in the above-mentioned processing processes for the wear-resistant coating for processing titanium alloy materials.

[0127] It should be noted that the order in which the embodiments of the present application are presented is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. Furthermore, the foregoing descriptions of specific embodiments of this specification are provided. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential sequence shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0128] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0129] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A processing technology for wear-resistant coating for titanium alloy material processing, characterized in that: The process includes: Pre-treating the tool substrate for processing titanium alloy, and depositing coating on the pre-treated tool substrate using plasma enhanced chemical vapor deposition technology; Real-time collection of plasma sheath voltage, radio frequency current, deposition chamber pressure, and substrate temperature during the coating deposition process; By constructing a fitness function in the optimization algorithm, the optimization algorithm is used to obtain the optimal flow rate of various gas components at different coating thicknesses during the coating deposition process. The construction of the fitness function includes: Based on the differences between the optimized flow rates of various gas components at different coating thicknesses and the preset target flow rates and actual flow rates during the coating deposition process, the composition gradient loss term of the coating deposition is determined by combining the plasma sheath voltage, RF current, and deposition chamber pressure during optimization using the optimization algorithm. Based on the differences in the optimized flow rates of various gas components at adjacent coating thicknesses during the coating deposition process and the substrate temperature during optimization, the transition smoothness loss term of the coating deposition is obtained. Combining the component gradient loss term and the transition smoothness loss term to obtain a fitness function in the optimization algorithm; After the coating is deposited to a set thickness, it is annealed and then cooled to room temperature; The expression of the component gradient loss term is: , where is the composition gradient loss term of coating deposition, 、 and They represent the plasma sheath voltage, RF current and deposition chamber pressure collected at the beginning of each optimization, Z represents the layer of the current coating thickness, and J represents the type of gas component controlled during the deposition process using PECVD technology. represents the optimized flow rate of the jth gas component when the coating thickness level is z, is the actual flow rate of the jth gas component when the coating thickness level is z, represents the target flow rate of the jth gas component when the coating thickness level is z, where the level is the number of each interval evenly divided into the set thickness of the coating and the intervals are arranged in ascending order; The expression of the transition smoothness loss term is: , where is the transition smoothness loss term of coating deposition, exp() is an exponential function with a natural constant as the base, represents the coating thickness interval of each layer, T represents the substrate temperature collected each time the optimization starts, Indicates the preset maximum temperature. is the optimized flow rate of the jth gas component when the coating thickness level is z-1.

2. The processing technology of a wear-resistant coating for titanium alloy material processing according to claim 1, characterized in that: The pretreatment includes: Immerse the tool substrate in a mixture containing 10%~30% HF and 20%~40% In the electrolyte, a pulse current with a frequency of 5~10Hz and a peak current density of 1~3A / cm² is applied. The activation degree of the substrate surface is monitored by the volt-ampere characteristic curve. The pretreatment is terminated when the volt-ampere characteristic curve tends to be stable.

3. The processing technology of a wear-resistant coating for processing titanium alloy materials according to claim 1, characterized in that: The parameter range of the plasma enhanced chemical vapor deposition technology is: The RF power is , the deposition chamber pressure is , the substrate temperature is , high purity argon Ar is used as carrier gas with a flow rate of 50~100sccm, and the titanium source is , heated to 50~70℃ by vaporizer, carried by carrier gas Ar with a flow rate of 1~5sccm; the carbon source is , nitrogen source is .

4. The processing technology of a wear-resistant coating for titanium alloy material processing according to claim 3, characterized in that: The wear-resistant coating deposited by the coating includes a bottom layer and a surface layer, the bottom layer is a TiC-rich layer, the thickness of which accounts for 20% to 30%; the surface layer is a TiN-rich layer, the thickness of which accounts for 70% to 80%.

5. The process for producing a wear-resistant coating for titanium alloy material processing according to claim 4, wherein: When depositing the bottom TiC-rich layer using plasma-enhanced chemical vapor deposition technology, control The flow rate is 15~20sccm, The flow rate is 10~15sccm and the bias voltage is -150 to -200V, forming a columnar crystal structure with a TiC content of 60%~80%; When using plasma enhanced chemical vapor deposition technology to deposit the surface TiN enriched layer, control The flow rate is 5~10sccm, The flow rate is 20~30sccm, the bias voltage is -50 to -100V, and a dense film layer with a TiN content of 70%~90% is formed.

6. The process for producing a wear-resistant coating for titanium alloy material processing according to claim 1, wherein: The fitness function in the optimization algorithm is the sum of the component gradient loss term and the transition smoothness loss term, and the optimization goal is to minimize the fitness function.

7. The process for producing a wear-resistant coating for titanium alloy material processing according to claim 1, wherein: The annealing treatment uses pulsed direct current with a current density of 5-10A / cm², a pulse width of 10-50ms, and an annealing time of 1-5min.

8. A wear-resistant coating for titanium alloy material processing, characterized in that: A wear-resistant coating for processing titanium alloy materials is produced by using the processing technology of the wear-resistant coating for processing titanium alloy materials as claimed in any one of claims 1 to 7.

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