PVD (Physical Vapor Deposition) coating process method applied to galvanized sheet stamping die

Abstract

The invention relates to the technical field of coatings, in particular to a PVD (Physical Vapor Deposition) coating process method applied to a galvanized sheet stamping die, which comprises the following steps of: pretreating the die, cleaning the surface of the die by a wet process, placing the die in a vacuum deposition cavity, vacuumizing, and heating to a preset temperature in an inert gas environment; plasma pretreatment is conducted on the surface of the mold, a high-power pulse magnetron sputtering cathode of a chromium target is selected to discharge in the argon working environment to generate plasma rich in chromium ions, and negative bias voltage is applied to the mold; starting at least one unbalanced magnetron sputtering cathode, gradually increasing the target current by the unbalanced magnetron sputtering cathode in a current ramp-up mode so as to improve the target voltage, and synchronously introducing nitrogen as a reaction gas, so that a nitride transition layer is deposited on the surface of the mold; and a high-power pulse magnetron sputtering cathode and an unbalanced magnetron sputtering cathode synchronously work on the transition layer to carry out multi-source reactive sputtering deposition, so that a multi-layer hard coating formed by alternating titanium aluminum vanadium and chromium nitride is formed. By combining the high-power pulse magnetron sputtering technology and the unbalanced magnetron sputtering technology, the problems that in the prior art, a coating is poor in adhesive force and insufficient in high temperature resistance are solved.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a PVD coating process for stamping dies of galvanized steel sheets. Background Technology

[0002] In the field of modern metal forming, stamping dies are widely used in the processing of various metal materials. Especially during operations such as stamping, deep drawing, and forming, the surface properties of the dies play a crucial role. Particularly in the stamping of metals such as galvanized sheet, dies are frequently exposed to harsh environments of high temperature, high pressure, and friction. This necessitates that the die materials possess excellent wear resistance, corrosion resistance, and oxidation resistance. However, traditional die materials, such as high-hardness steel or cemented carbide, are prone to problems such as coating peeling and accelerated wear when exposed to high temperatures and long-term friction, thus affecting the service life and processing quality of the dies.

[0003] To address this issue, coating technology has become a crucial means of improving mold performance. In recent years, physical vapor deposition (PVD) technology has been widely used for hard coating treatments on mold surfaces, forming a dense coating to enhance wear resistance, oxidation resistance, and corrosion resistance. However, existing coating technologies still suffer from problems such as insufficient coating adhesion, poor coating uniformity, and inadequate high-temperature resistance. These issues limit the application of PVD coating technology in high-intensity and high-temperature environments. Especially during prolonged use and high-intensity stamping operations, the coating is prone to peeling off, causing mold damage and production stoppages. Summary of the Invention

[0004] In view of the above technical problems, the present invention provides a PVD coating process for stamping dies of galvanized sheet, which solves the problems of poor coating adhesion and insufficient high temperature resistance in the prior art by combining high-power pulsed magnetron sputtering and unbalanced magnetron sputtering technology.

[0005] Other features and advantages of this disclosure will become apparent from the following detailed description, or may be learned in part from practice of this disclosure.

[0006] According to one aspect of the present invention, a PVD coating process for stamping dies of galvanized steel sheets is provided, the method comprising steps S1-S4: S1: Pre-treat the mold by wet cleaning the mold surface and then placing it in a vacuum deposition chamber to evacuate to... Below mbar, and heated to a predetermined temperature in an inert gas environment; S2: Plasma pretreatment is performed on the surface of the mold. A high-power pulsed magnetron sputtering cathode with a chromium target is selected to discharge in an argon working environment to generate plasma rich in chromium ions. A negative bias voltage is applied to the mold to inject chromium ions into the mold surface and bombard the surface with argon ions to remove the surface, thereby forming a dense modified layer on the mold surface. S3: While maintaining the plasma, at least one unbalanced magnetron sputtering cathode is turned on. The unbalanced magnetron sputtering cathode gradually increases the target current in a current ramp-up mode to improve the target voltage, and nitrogen is introduced as a reaction gas at the same time to deposit a nitride transition layer on the mold surface. S4: On the transition layer, the high-power pulsed magnetron sputtering cathode and the unbalanced magnetron sputtering cathode work synchronously to perform multi-source reactive sputtering deposition, forming a multilayer hard coating composed of alternating titanium aluminum vanadium and chromium nitrides. The unbalanced magnetron sputtering cathode target includes a Ti50Al50 alloy target and a TiAl6V4 alloy target. The high-power pulsed magnetron sputtering cathode target and the unbalanced magnetron sputtering cathode target simultaneously sputter TiAlV alloy and Cr metal target in a nitrogen atmosphere, so that the TiAlV nitride layer and the Cr nitride layer grow alternately to form the multilayer hard coating.

[0007] Furthermore, in step S1, the mold is heated for 1.5 hours in an environment containing argon and 20% hydrogen, raising the mold temperature to 400°C.

[0008] Furthermore, in step S2, the plasma pretreatment includes: first in approximately The mold was subjected to a pure argon atmosphere of mbar. A glow discharge cleaning process was performed for 30 minutes with a bias voltage of 800 V, followed by... Under an argon pressure of mbar, a high-power pulsed magnetron sputtering cathode with a chromium target was used for 25 minutes of plasma bombardment. The high-power pulsed magnetron sputtering cathode had a pulse power of 12 kW and a pulse voltage of [missing value]. A peak value of 1000 V, a frequency of 500 Hz, and a pulse width of 160 µs are applied to the mold simultaneously. An 800V bias voltage with a pulse width of 600 µs was used to inject chromium ions into the mold surface and achieve argon ion bombardment etching cleaning.

[0009] Furthermore, during the 15 minutes of plasma in step S3, the discharge of the high-power pulsed magnetron sputtering cathode is maintained, and the two unbalanced magnetron sputtering cathodes equipped with Ti50Al50 and TiAl6V4 targets are simultaneously activated. The target voltage is increased by linearly increasing the discharge current of the unbalanced magnetron sputtering cathodes from 10A to 30A. 550 V, while simultaneously introducing nitrogen gas and linearly increasing the nitrogen flow rate from 160 sccm to 360 sccm, the target voltage is stabilized and controlled using fine-tuning of the magnetic field. 550 V, thus maintaining an unbalanced magnetron sputtering discharge current density of approximately 6 mA / cm^2 on the target surface; after 7 minutes of plasma application, the bias voltage applied to the mold is switched to DC mode and from 500V linear drop A 125V DC bias voltage is applied to complete the formation of the transition layer.

[0010] Furthermore, the mold is mounted on a rotatable clamping device for deposition, which rotates at a speed of 2 rpm around a vertical axis within the deposition chamber while also rotating on its own axis, thereby achieving uniform deposition of the multilayer hard coating on the mold surface.

[0011] Furthermore, in step S4, during multi-source reactive sputtering deposition, a first deposition mode and a second deposition mode are executed sequentially. In the first deposition mode, two high-power pulsed magnetron sputtering cathodes, corresponding to the longer target sections of the unbalanced magnetron sputtering cathode, are energized to deposit at least two-thirds of the length of the deposition mold. In the second deposition mode, one high-power pulsed magnetron sputtering cathode, corresponding to the shorter target sections of the unbalanced magnetron sputtering cathode, is energized to deposit the remaining length of the deposition mold. During either the first or second deposition mode, the unused target sections are shielded with a shielding baffle to prevent cross-contamination.

[0012] Furthermore, after step S4 is completed, the discharge of the high-power pulsed magnetron sputtering cathode is stopped, and the TiAlVN top coating is continued to be sputtered and deposited in a nitrogen atmosphere using only the unbalanced magnetron sputtering cathodes with Ti50Al50 and TiAl6V4 targets for 5 minutes.

[0013] Furthermore, steps S1 to S4 are performed within an octagonal prism-shaped vacuum deposition chamber, which is equipped with two unbalanced magnetron sputtering cathodes and three high-power pulsed magnetron sputtering cathodes. The two unbalanced magnetron sputtering cathodes are respectively equipped with Ti50Al50 alloy targets and TiAl6V4 alloy targets. The high-power pulsed magnetron sputtering cathodes are all equipped with chromium targets. The targets of the unbalanced magnetron sputtering cathodes are segmented along their length in a 2:1 ratio. The high-power pulsed magnetron sputtering cathodes are arranged opposite to the unbalanced magnetron sputtering cathodes for segmented deposition.

[0014] The technical solution disclosed herein has the following beneficial effects: By employing a combination of high-power pulsed magnetron sputtering and unbalanced magnetron sputtering, multilayer titanium aluminum vanadium nitride and chromium nitride coatings can be deposited on the mold surface, significantly improving the coating's hardness and adhesion. This method achieves coating densification and homogenization through precise control of atmosphere and current variations during the sputtering process, ensuring the coating's stability and durability under high temperature, high pressure, and high friction environments. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating a PVD coating process applied to stamping dies for galvanized steel sheets, as described in this specification. Figure 2 This is a schematic diagram of the horizontal cross-sectional structure of the PVD equipment in the embodiments of this specification; Figure 3 This is a schematic diagram showing the distribution of the various components of the PVD equipment in the embodiments of this specification. Detailed Implementation

[0016] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this disclosure more comprehensive and complete, and to fully convey the concept of the example embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced with one or more of the specific details omitted, or other methods, components, apparatus, steps, etc., can be employed. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0017] This invention provides a method for applying a product to a PVD coating process for stamping dies of galvanized steel sheets. (Refer to...) Figure 1 The diagram shown is a flowchart illustrating a PVD coating process for galvanized sheet stamping dies according to an embodiment of the present invention. The method may specifically include steps S1-S4, as follows: Figure 2-3 As shown, steps S1 to S4 are performed in a PVD equipment, which is an octagonal prism-shaped vacuum deposition chamber. The door panel of the vacuum deposition chamber is divided into eight regions 1 to 8 clockwise. In the first region 1, two first unbalanced magnetron sputtering cathodes 11 are inserted into the chamber from the outside of the door panel, respectively equipped with Ti50Al50 alloy targets and TiAl6V4 alloy targets, and are divided into long target section A and short target section B along the length direction in a 2:1 ratio. Similarly, in the seventh region 7, two second unbalanced magnetron sputtering cathodes 71 are also arranged as follows. Figure 3 A and B in the cavity; the cavity also contains three high-power pulsed magnetron sputtering cathodes equipped with chromium targets, of which two first high-power pulsed magnetron sputtering cathodes 51 are arranged on the same door plate in the fifth region 5, as shown in Figure 5. Figure 3 The first part is divided into T1 and T3. The second high-power pulsed magnetron sputtering cathode 31 of the other unit is arranged on the opposite side panel and parallel to T1 and T3, that is, in the third region 3. Figure 3 In the case of T2, when the three are compared along a straight line, T1 / T3 The ends of T1 and T2 slightly overlap; each unbalanced magnetron sputtering cathode is provided with an adjustable shielding door on its outer side, such as the first shielding door 12 of the first region 1 and the second shielding door 71 of the seventh region 7, to prevent cross-contamination during chromium target pre-sputtering or segmented operation; all cathodes are equipped with a magnet lifting mechanism to maintain an effective magnetic field strength of about 35mT during target surface erosion, and the unbalanced magnetron sputtering cathode 72 is provided with a booster coil on its outer periphery to push the plasma towards the center of the cavity, such as the first booster coil 13 of the first region 1 and the second booster coil 73 of the seventh region 7; the unbalanced magnetron sputtering cathodes between the first and seventh regions form the eighth region 8, where an anode 82 is arranged, and a central gas inlet 81 is integrated on the back of the anode 82 for introducing process gas; along the direction corresponding to the target length of the unbalanced magnetron sputtering cathode, i.e., the fourth region 4, a turbomolecular pump group 41 is provided, which is connected to the cavity through a gate valve 42, and the turbomolecular pump group 41 is located at a target length of about 2.5 m. Five units are vertically distributed within the range. A heating element 21 is located on one side of the second region 2 within the cavity, and a rotating support disk 91 is located in the center. The rotating support disk 91 revolves at approximately 2 rpm, and the mold rotates on its own axis at approximately 7 rpm. When the mold first passes the cathode front, the distance between the mold and the target surface is controlled at approximately 120–170 mm to facilitate the segmented deposition of the long target section A and the short target section B, achieving uniform coating along the entire length of the mold. The second region 2 and the sixth region 6 are respectively equipped with a first heater 21 and a second heater 61 for heating the reaction process.

[0018] The method may specifically include steps S1-S4 as follows: In step S1, the mold is pretreated by wet cleaning and then placed in a vacuum deposition chamber where a vacuum is drawn until... Below mbar, it is heated to a predetermined temperature in an inert gas environment. This pretreatment heating helps to further remove residual oxides on the surface and release adsorbed gases, thereby activating the mold surface and laying a good foundation for subsequent coating deposition.

[0019] Specifically, the mold is heated for 1.5 hours in an environment containing argon and 20% hydrogen, raising the mold temperature to 400°C.

[0020] The process begins with wet cleaning to remove oil, dust, and other impurities from the mold surface. The cleaned mold is then placed in a vacuum deposition chamber and evacuated to a low pressure to ensure subsequent processes are performed in a highly clean environment. Next, the mold is heated to a predetermined temperature in an inert gas atmosphere. This pretreatment heating helps to further remove residual oxides from the surface and release adsorbed gases, thereby activating the mold surface and laying a good foundation for subsequent coating deposition.

[0021] In step S2, plasma pretreatment is performed on the surface of the mold. A high-power pulsed magnetron sputtering cathode with a chromium target is selected to discharge in an argon working environment to generate plasma rich in chromium ions. A negative bias voltage is applied to the mold to inject chromium ions into the mold surface and bombard the surface with argon ions to remove the surface, thereby forming a dense modified layer on the mold surface.

[0022] This process utilizes high-power pulsed magnetron sputtering technology to provide metal ions, selects chromium as the target material, generates Cr+ and Cr2+ ions, and applies a negative bias voltage to implant chromium atoms into the steel substrate. At the same time, the cleaning effect of argon ion etching is superimposed, which significantly improves the reproducibility of the adhesion of subsequent hard coatings. It is similar to the influence of multiple ionized metal atoms in the cathode arc process, but completely eliminates the droplet effect.

[0023] Specifically, the plasma pretreatment includes: first in approximately The mold was subjected to a pure argon atmosphere of mbar. A glow discharge cleaning process was performed for 30 minutes with a bias voltage of 800 V, followed by... Under an argon pressure of mbar, a high-power pulsed magnetron sputtering cathode with a chromium target was used for 25 minutes of plasma bombardment. The high-power pulsed magnetron sputtering cathode had a pulse power of 12 kW and a pulse voltage of [missing value]. A peak value of 1000 V, a frequency of 500 Hz, and a pulse width of 160 µs are applied to the mold simultaneously. An 800V bias voltage with a pulse width of 600 µs is used to ensure that a large number of chromium ions are injected into the mold surface under high voltage acceleration, while argon ions continuously bombard and etch the surface layer to achieve chromium implantation modification and deep cleaning.

[0024] In step S3, at least one unbalanced magnetron sputtering cathode is turned on while maintaining the plasma. The unbalanced magnetron sputtering cathode gradually increases the target current in a current ramp-up mode to improve the target voltage, and nitrogen is introduced simultaneously as a reactive gas, thereby depositing a nitride transition layer on the mold surface.

[0025] Specifically, during the 15-minute plasma run, the high-power pulsed magnetron sputtering cathode is maintained in discharge, and simultaneously, two unbalanced magnetron sputtering cathodes equipped with Ti50Al50 and TiAl6V4 targets are activated. The target voltage is increased by linearly increasing the discharge current of the unbalanced magnetron sputtering cathodes from 10A to 30A. 550 V, while simultaneously introducing nitrogen gas and linearly increasing the nitrogen flow rate from 160 sccm to 360 sccm, the target voltage is stabilized and controlled using fine-tuning of the magnetic field. 550 V, thus maintaining an unbalanced magnetron sputtering discharge current density of approximately 6 mA / cm^2 on the target surface; after 7 minutes of plasma application, the bias voltage applied to the mold is switched to DC mode and from 500V linear drop A 125V DC bias voltage is applied to complete the formation of the transition layer.

[0026] Step S3 involves establishing a compositional and energy gradient interface between the substrate and the subsequent hard film, maintaining the plasma environment created by the preceding discharge, and activating at least one unbalanced magnetron sputtering cathode to participate in the formation of a nitride transition layer. Specifically, during the approximately 15-minute transition phase, the discharge parameters of the high-power pulsed magnetron sputtering cathode on the chromium target are maintained consistent with the preceding step to provide a stable and dense metal ion / inert ion background. Simultaneously, two unbalanced magnetron sputtering cathodes equipped with Ti50Al50 alloy targets and TiAl6V4 alloy targets are activated. Both cathodes employ a current ramp-up mode, linearly increasing the discharge current from 10 A to 30 A. Through this linear current ramp-up, the target surface discharge conditions smoothly transition to the high-power region, and the target voltage is boosted and stabilized at approximately [value missing]. A voltage of 550 V is beneficial for maintaining sufficient ion density and ion energy in the target sheath layer, thereby increasing the flux of active species reaching the mold surface and the densification of the initial layer. Simultaneously with the current ramp-up, nitrogen is introduced as the reactant gas, linearly increasing the flow rate from 160 sccm to 360 sccm. This allows the metal active species to react with nitrogen promptly upon reaching the mold surface, continuously generating a dense metal nitride transition layer. To achieve long-term repeatability of discharge and reaction conditions, a magnetic field "fine-tuning" mechanism (dynamically compensating for the gaps in the magnet array / magnetic circuit) is used to stably control the target voltage at approximately [value missing]. 550 V; at this voltage platform, the plasma current density of the unbalanced magnetron sputtering cathode can be maintained at about 6 mA / cm² on the target surface, ensuring the stability and controllability of material transport and reaction generation during the transition period from the source.

[0027] The transition layer formed under the above conditions promotes surface densification and micro-intercalation in the early deposition stage through a high ion / neutral ratio and moderate ion energy, enhancing the mechanical bonding and chemical adhesion of subsequent layers at the interface. Furthermore, the simultaneous ramping of metal and nitrogen flux ensures a smooth transition of the metal-to-nitride phase composition along the thickness direction during film formation, avoiding stress concentration, porosity, or a sharp increase in roughness caused by abrupt reactions, thus facilitating further optimization of energy input and defect control. After maintaining the plasma for approximately 7 minutes, the bias voltage applied to the mold is switched from a higher accelerating potential to DC mode, and then... 500 V linearly decreases to A 125 V DC bias was applied. The purpose of this bias path was to maintain a high bias in the first half to enhance densification and decontamination during the interface preparation stage; and to reduce the bias in the second half to minimize damage from re-sputtering and ion bombardment, suppressing excessive internal stress while avoiding grain coarsening or interface disturbance caused by excess energy, thereby obtaining a smoother, more continuous transition layer surface without obvious defects. Throughout the 15-minute stage, the discharge power, gas flow rate, and fine-tuning of the magnetic field were coordinated to ensure a stable plateau for the target voltage and current density, a sufficient supply of reactive nitrogen, and controllable decay of ion energy. This resulted in the transition layer exhibiting a gradual transition from metal-rich to stoichiometric nitrides in the thickness direction, providing suitable interface conditions for subsequent multi-source co-sputtering multilayer film growth with high density and high bonding strength.

[0028] In step S4, the high-power pulsed magnetron sputtering cathode and the unbalanced magnetron sputtering cathode are used simultaneously on the transition layer to perform multi-source reactive sputtering deposition, forming a multilayer hard coating composed of alternating titanium aluminum vanadium and chromium nitrides. The unbalanced magnetron sputtering cathode target includes a Ti50Al50 alloy target and a TiAl6V4 alloy target. The high-power pulsed magnetron sputtering cathode target and the unbalanced magnetron sputtering cathode target are used to simultaneously sputter TiAlV alloy and Cr metal target in a nitrogen atmosphere, so that TiAlV nitride layers and Cr nitride layers grow alternately to form the multilayer hard coating.

[0029] Specifically, during multi-source reactive sputtering deposition, a first deposition mode and a second deposition mode are executed sequentially. In the first deposition mode, two high-power pulsed magnetron sputtering cathodes, corresponding to the longer target sections of the unbalanced magnetron sputtering cathode, are energized to deposit at least two-thirds of the length of the deposition mold. In the second deposition mode, one high-power pulsed magnetron sputtering cathode, corresponding to the shorter target sections of the unbalanced magnetron sputtering cathode, is energized to deposit the remaining length of the deposition mold. During either the first or second deposition mode, the target sections not involved in the deposition are shielded using a shielding baffle to prevent cross-contamination.

[0030] After step S4 is completed, the discharge of the high-power pulsed magnetron sputtering cathode is stopped, and the TiAlVN top coating is continued to be sputtered in a nitrogen atmosphere using only the Ti50Al50 target and the TiAl6V4 target. The deposition time is 5 minutes.

[0031] As an explanation, step S4 involves constructing an alternating layered hard film system on the formed nitride transition layer. This is achieved by simultaneously operating a high-power pulsed magnetron sputtering cathode and an unbalanced magnetron sputtering cathode, performing multi-source reactive sputtering deposition in a nitrogen atmosphere. Operationally, the discharge and bias settings from the end of the transition layer are maintained. Two unbalanced magnetron sputtering cathodes are loaded with Ti50Al50 alloy targets and TiAl6V4 alloy targets, respectively, while a chromium target is loaded by the high-power pulsed magnetron sputtering cathode. All three participate in deposition within the same process window, allowing titanium-aluminum-vanadium nitrides and chromium nitrides to grow alternately on the mold surface, resulting in a (TiAlV / Cr)N multilayer structure. Under typical conditions, this simultaneous deposition can produce a multilayer coating approximately 1.6 µm thick in about 52 minutes, with a deposition rate of approximately 0.51 nm / s. Specific parameters are maintained consistent with those from the end of the transition layer to ensure discharge stability and interlayer interface continuity. To achieve "alternating growth", the non-equilibrium magnetron sputtering cathode continuously provides Ti–Al–V precursors, while the pulsed high-power chromium cathode provides Cr precursors under the same nitrogen partial pressure. Relying on the revolution / rotation of the mold and the field strength distribution, periodic composition fluctuations and phase superpositions are formed, thereby constructing alternating layers in the thickness direction.

[0032] To ensure the clarity and regularity of the multilayer structure, the atmosphere and discharge settings are maintained in accordance with those at the end of the transition layer during the deposition process. Spatially selective supply is achieved through segmentation and shielding of the equipment: In the first deposition mode, two high-power pulsed magnetron sputtering chromium cathodes corresponding to the longer target section are activated, working in conjunction with the two unbalanced magnetron sputtering cathodes to complete the deposition of at least two-thirds of the mold length. Then, the system switches to the second deposition mode, activating only one high-power pulsed magnetron sputtering chromium cathode corresponding to the shorter target section to complete the deposition of the remaining length. The two modes are controlled automatically by adjusting the magnet's "coarse / fine" displacement and shutter movement to ensure that discharge and incident only occur within the target section. Simultaneously, the unused target sections are shielded to prevent cross-contamination of passive sections by chromium or Ti-Al-V seed sources, thus achieving uniform periodic layers and consistent thickness accumulation throughout the entire length. This segmented method, combined with the 2 rpm revolution and 7 rpm rotation of the rotating fixture and the 120–170 mm leading edge spacing control, allows each layer to receive sufficient ion irradiation and precursor stream in different orientations, thereby improving interlayer compactness and interface integrity, which is conducive to obtaining regular periodic structures and higher deposition density.

[0033] In the multilayer film system obtained by synchronous deposition, chromium nitrides tend to form a face-centered cubic structure with (200) orientation under the above reaction conditions. Its strong orientation dominates in the periodic stack and suppresses the (111) orientation common in TiAlV nitrides, thereby further enhancing the layer / layer interface difference and periodicity, which is beneficial to the overall hardness and wear resistance of the coating. Through cross-sectional abrasion observation, clear light and dark alternating layers are visible, and the double-layer periodic thickness is about 0.07 µm, indicating that under stable gas pressure, bias voltage and power combination, the alternating stack advances regularly along the thickness direction, which is conducive to maintaining the periodic repeatability and functional uniformity of the multilayer structure within the macroscopic thickness. The above structure and orientation results are directly derived from the competitive deposition and ion assistance of the synchronously supplied Ti–Al–V and Cr precursors under the same nitrogen partial pressure, which depends on the linkage of bias voltage-power-gas flow, thereby maintaining the repeatable stacking of interlayer composition and crystal orientation throughout the deposition period.

[0034] After completing multi-source reactive sputtering deposition and achieving the target thickness, the high-power pulsed magnetron sputtering chromium cathode was shut down, leaving only two unbalanced magnetron sputtering cathodes to continue sputtering in a nitrogen atmosphere for approximately 5 minutes, depositing a thin TiAlVN top layer. This top layer provides a low-friction, easily observable wear-covering band on the surface without altering the multilayer periodic structure of the substrate. Furthermore, it utilizes the discharge / bias voltage stability window maintained in the previous stage to achieve seamless integration and interface continuity with the underlying multilayer film, thus functionally and process-wise completing the surface finishing and performance enhancement of the multilayer hard coating.

[0035] The technical solution disclosed herein has the following beneficial effects: By employing a combination of high-power pulsed magnetron sputtering (HIPIMS) and unbalanced magnetron sputtering (UBM), multilayer titanium aluminum vanadium nitride and chromium nitride coatings can be deposited on the mold surface, significantly improving the coating's hardness and adhesion. This method achieves coating densification and homogenization through precise control of atmosphere and current variations during the sputtering process, ensuring the coating's stability and durability under high temperature, high pressure, and high friction environments.

[0036] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0037] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A PVD coating process for stamping dies of galvanized steel sheets, characterized in that, The method includes steps S1-S4: S1: Pre-treat the mold by wet cleaning the mold surface and then placing it in a vacuum deposition chamber to evacuate to... Below mbar, and heated to a predetermined temperature in an inert gas environment; S2: Plasma pretreatment is performed on the surface of the mold. A high-power pulsed magnetron sputtering cathode with a chromium target is selected to discharge in an argon working environment to generate plasma rich in chromium ions. A negative bias voltage is applied to the mold to inject chromium ions into the mold surface and bombard the surface with argon ions to remove the surface, thereby forming a dense modified layer on the mold surface. S3: While maintaining the plasma, at least one unbalanced magnetron sputtering cathode is turned on. The unbalanced magnetron sputtering cathode gradually increases the target current in a current ramp-up mode to improve the target voltage, and nitrogen is introduced as a reaction gas at the same time to deposit a nitride transition layer on the mold surface. S4: On the transition layer, the high-power pulsed magnetron sputtering cathode and the unbalanced magnetron sputtering cathode work synchronously to perform multi-source reactive sputtering deposition, forming a multilayer hard coating composed of alternating titanium aluminum vanadium and chromium nitrides. The unbalanced magnetron sputtering cathode target includes a Ti50Al50 alloy target and a TiAl6V4 alloy target. The high-power pulsed magnetron sputtering cathode target and the unbalanced magnetron sputtering cathode target simultaneously sputter TiAlV alloy and Cr metal target in a nitrogen atmosphere, so that the TiAlV nitride layer and the Cr nitride layer grow alternately to form the multilayer hard coating.

2. The PVD coating process for galvanized sheet stamping dies according to claim 1, characterized in that, In step S1, the mold is heated for 1.5 hours in an environment containing argon and 20% hydrogen, raising the mold temperature to 400°C.

3. The PVD coating process for galvanized sheet stamping dies according to claim 1, characterized in that, In step S2, the plasma pretreatment includes: first, in approximately... The mold was subjected to a pure argon atmosphere of mbar. A glow discharge cleaning process was performed for 30 minutes with a bias voltage of 800 V, followed by... Under an argon pressure of mbar, a high-power pulsed magnetron sputtering cathode with a chromium target was used for 25 minutes of plasma bombardment. The high-power pulsed magnetron sputtering cathode had a pulse power of 12 kW and a pulse voltage of [missing value]. A peak value of 1000 V, a frequency of 500 Hz, and a pulse width of 160 µs are applied to the mold simultaneously. An 800V bias voltage with a pulse width of 600 µs was used to inject chromium ions into the mold surface and achieve argon ion bombardment etching cleaning.

4. The PVD coating process for galvanized sheet stamping dies according to claim 1, characterized in that, During the 15 minutes of plasma in step S3, the discharge of the high-power pulsed magnetron sputtering cathode is maintained, and the two unbalanced magnetron sputtering cathodes equipped with Ti50Al50 and TiAl6V4 targets are simultaneously activated. The target voltage is increased by linearly increasing the discharge current of the unbalanced magnetron sputtering cathodes from 10A to 30A. 550 V, while simultaneously introducing nitrogen gas and linearly increasing the nitrogen flow rate from 160 sccm to 360 sccm, the target voltage is stabilized and controlled using fine-tuning of the magnetic field. 550 V, thus maintaining an unbalanced magnetron sputtering discharge current density of approximately 6 mA / cm^2 on the target surface; after 7 minutes of plasma application, the bias voltage applied to the mold is switched to DC mode and from 500V linear drop A 125V DC bias voltage is applied to complete the formation of the transition layer.

5. The PVD coating process for galvanized sheet stamping dies according to claim 1, characterized in that, The mold is mounted on a rotatable clamping device for deposition. The device rotates at 2 rpm around a vertical axis within the deposition chamber while also rotating on its own axis, thereby achieving uniform deposition of the multilayer hard coating on the mold surface.

6. The PVD coating process for galvanized sheet stamping dies according to claim 1, characterized in that, In step S4, during multi-source reactive sputtering deposition, a first deposition mode and a second deposition mode are executed sequentially. In the first deposition mode, two high-power pulsed magnetron sputtering cathodes, corresponding to the longer target sections of the unbalanced magnetron sputtering cathode, are energized to deposit at least two-thirds of the length of the deposition mold. In the second deposition mode, one high-power pulsed magnetron sputtering cathode, corresponding to the shorter target sections of the unbalanced magnetron sputtering cathode, is energized to deposit the remaining length of the deposition mold. During either the first or second deposition mode, the unused target sections are shielded with a shielding baffle to prevent cross-contamination.

7. The PVD coating process for galvanized sheet stamping dies according to claim 1, characterized in that, After step S4 is completed, the discharge of the high-power pulsed magnetron sputtering cathode is stopped, and the TiAlVN top coating is continued to be sputtered in a nitrogen atmosphere using only the Ti50Al50 target and the TiAl6V4 target. The deposition time is 5 minutes.

8. The PVD coating process for galvanized sheet stamping dies according to claim 1, characterized in that, Steps S1 to S4 are performed in an octagonal prism-shaped vacuum deposition chamber, which is equipped with two unbalanced magnetron sputtering cathodes and three high-power pulsed magnetron sputtering cathodes. The two unbalanced magnetron sputtering cathodes are respectively equipped with Ti50Al50 alloy targets and TiAl6V4 alloy targets. The high-power pulsed magnetron sputtering cathodes are all equipped with chromium targets. The targets of the unbalanced magnetron sputtering cathodes are segmented along the length direction at a ratio of 2:

1. The high-power pulsed magnetron sputtering cathodes are arranged opposite to the unbalanced magnetron sputtering cathodes for segmented deposition.

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