A method for controlling defects in PVD deposited coatings using an ion etching process

Abstract

The present invention relates to the technical field of PVD coating production processes, and more specifically, to a method for controlling defects in PVD deposited coatings using an ion etching process. This method employs a column arc (Ti target) to ion-etch a sample under the action of an auxiliary anode. Inert gas (argon) is used as the reaction gas, and the resulting plasma achieves the ion etching effect, thereby reducing coating deposition defects. Characterization equipment is used to analyze the microstructure before and after ion etching, and the corrosion behavior of different coatings in a 3.5 wt.% NaCl solution is further analyzed. The introduction of ion etching effectively reduces the number of defects while improving the electrochemical properties of the coating.

Description

Technical Field

[0001] The invention relates to the technical field of PVD coating production technology, and in particular to a method for controlling defects in PVD deposited coatings using an ion etching process. Background Art

[0002] As humanity's development of marine resources deepens, marine engineering equipment, particularly key components such as ship hydraulic systems, drilling pumps, gears, worm gears, and worms, are experiencing significant corrosion and wear issues in harsh service environments such as high salinity, high temperature, high humidity, high speed, and heavy loads. Corrosion and wear interact strongly, and the influencing mechanisms are extremely complex, severely shortening the service life of marine engineering equipment. Using advanced surface protection technologies to extend the service life of key components is a common engineering practice. In recent decades, hard coatings, particularly transition metal nitrides, have garnered widespread attention due to their excellent wear and corrosion resistance.

[0003] Hard coatings deposited using physical vapor deposition (PVD) often exhibit a columnar crystal structure and inevitably contain various growth defects, including large particles, pinholes, pores, and microcracks. When the coating is exposed to corrosive media, electrolytes in the solution can penetrate through these defects to the coating / substrate interface, causing anodic dissolution of the substrate and reducing the service life of the associated components.

[0004] Ion etching technology is a common surface treatment technology and is widely used in physical vapor deposition technology. When using vacuum coating technologies such as magnetron sputtering and arc ion plating to prepare coatings, ion etching is usually used to treat the surface of the substrate to improve the adhesion and other properties of the coating. For example, Chinese invention patent application CN201710205933.8 discloses an ion etching cleaning process for PVD coatings. In the process of preparing coatings using physical vapor deposition technology, ion etching is used to remove residual substances such as oxides, grease, and microparticles adsorbed on the surface of the workpiece, as well as to remove metallic oxides on the surface of the workpiece, activate the surface energy of the workpiece, thereby improving the adhesion between the PVD coating and the workpiece substrate and improving the various properties of the coating. Inert gas (argon (Ar) or neon (Ne), gas flow rate 75-100sccm, negative bias 350-450V), inert gas (argon (Ar) or neon (Ne), 25-50sccm, negative bias 400-500V) and non-inert gas (hydrogen (H2) or oxygen (O2), 50-75sccm, negative bias 550-650V), non-inert gas (hydrogen (H2) or oxygen (O2), 75-125sccm, negative bias 700-800V) are used to gradually etch the substrate surface. This invention patent application effectively changes the surface state of the workpiece and optimizes the bonding strength between the coating and the substrate. However, the ion etching method has complicated steps and only changes the film-substrate bonding strength of the coating, and does not significantly improve the various properties of the coating. When coating on a substrate, an intermediate treatment method is also often used to improve the coating performance. For example, the published scientific paper Controllable defect engineering to enhance the corrosion resistance of Cr / GLC multilayered coating for deep-sea applications (CORROSION SCIENCE[J].2022,199:http: / / dx.doi.org / 10.1016 / j.corsci.2022.110175.) uses intermediate cleaning treatment to reduce the density of penetrating defects in the coating, thereby improving the local corrosion resistance of the coating. Cr / GLC multilayer coatings were prepared on stainless steel substrates by DC magnetron sputtering technology. First, an inert gas (Ar) was introduced under a substrate bias voltage of -200 V, and Ar was used. +The substrate was etched and pre-cleaned for 40 minutes, and manual cleaning interventions were introduced once and twice during the deposition of the coating to remove adsorbed particles on the coating surface. The manual intervention steps adopted by the authors are: remove the partially deposited coating from the equipment, place it in an alcohol-containing detergent for ultrasonic cleaning for 15 minutes, wipe the surface with a cotton swab, dry it with high-pressure pure N2, and finally place the sample in the equipment to continue deposition. Introducing two manual cleaning interventions will require repeating the above steps again. This method does not change the mechanical properties and corrosion and wear properties of the coating, effectively controls the through defects generated during the deposition process, and improves the local corrosion performance of the coating. This manual intervention method frequently opens the equipment to remove samples for cleaning, reduces the efficiency of deposition, and destroys the vacuum environment during the deposition process. Although a short period of ion etching is subsequently used to remove surface oxides, there are still uncertain factors that affect the coating performance.

[0005] In view of the above-mentioned defects, the inventors of the present invention finally obtained the present invention after a long period of research and practice. Summary of the Invention

[0006] The purpose of the present invention is to solve the problem of how to reduce the generation of coating growth defects, thereby improving the corrosion resistance of the hard coating, and provide a method for controlling PVD deposited coating defects by an ion etching process.

[0007] In order to achieve the above object, the present invention discloses a method for controlling defects in PVD deposited coatings by an ion etching process, comprising the following steps:

[0008] S1, sample surface pretreatment: Use coarse sandpaper to grind and remove rust from the sample surface, then use fine sandpaper to polish the surface, and then use polishing equipment to polish the sample surface to a mirror surface. Finally, put the polished sample into alcohol for ultrasonic cleaning and drying;

[0009] S2, clamping the sample: After fixing the surface pre-treated sample with a clamp, place it on the rotating rack in the furnace chamber;

[0010] S3, vacuum the equipment: pump the pressure in the chamber to P≤5.0×10 -4 mbar;

[0011] S4, equipment heating: the sample is heated to 300°C through the heating tube on the wall of the equipment cavity, and the heating time is 3600s;

[0012] S5, glow cleaning of the sample: argon gas is introduced into the chamber, the bias voltage is set to -400 V, and the sample surface is glow cleaned;

[0013] S6, ion etching and cleaning of the sample: Argon gas is introduced into the chamber, the bias voltage is set to -300V, and the Ti target is turned on. The Ti ions sputtered from the target are blocked by the shielding cover, and the generated electrons bombard and ionize the argon gas under the action of the auxiliary anode. The generated plasma etches and cleans the sample surface;

[0014] S7, deposition of a transition layer on the sample: After the sample is ion-etched and cleaned, argon gas is introduced into the chamber, and the Cr target is turned on. Particles sputtered from the target are deposited on the sample surface to form a Cr metal transition layer.

[0015] S8, preparation of CrN / NbN coating: stop the argon flow, introduce nitrogen into the chamber, alternately turn on or simultaneously turn on the Cr target and Nb target arc power supplies, and combine the particles sputtered from the target with the particles ionized by the nitrogen to form a CrN / NbN multilayer / nano-multilayer coating. During the coating preparation process, three ion etchings are inserted, each lasting 600 s.

[0016] S9, sample cooling and sampling: After deposition is completed, take out the sample when the furnace chamber temperature cools down to below 120°C.

[0017] In step S6, argon gas was introduced to stabilize the pressure in the chamber at 1.6×10 -2 mbar, the bias voltage is -300 V, and the current of the Ti target is 80 A.

[0018] In step S6, the duration of etching and cleaning is 1800 seconds.

[0019] In step S7, argon gas was introduced to stabilize the pressure in the chamber at 3.5×10 -2 mbar, and the current of the Cr target is 100A.

[0020] In step S8, nitrogen gas was introduced and the pressure in the chamber was stabilized at 3.5×10 -2 mbar, the current of the Cr target is 120A, the current of the Nb target is 160A, and the substrate bias is -80V.

[0021] In step S8, the specific process is as follows:

[0022] S81, stop the argon flow, and introduce nitrogen into the chamber, and the pressure is stabilized at 3.5×10 -2mbar, then power on target No. 1, set the target current to 120A, the bias to -80V, and the deposition time to 1260s, then cut off the current of target No. 1, power on target No. 3, set the target current to 160A, the bias to -80V, and the deposition time to 660s, and repeat the deposition cycle twice; or power on targets No. 1 and 3 at the same time, set the target currents to 120A and 160A respectively, set the bias to -80V, and the deposition time to 1560s;

[0023] S82, stop the nitrogen flow, and introduce argon into the chamber, and the pressure is stabilized at 1.6×10 -2 mbar, the column arc target was powered on, the target current was set to 80A, the bias voltage was set to -300V, targets 2 and 3 were auxiliary anodes, the ion source current was 80A, and the etching time was 600s;

[0024] S83, stop the argon flow, and introduce nitrogen into the chamber until the pressure is stabilized at 3.5×10 -2 mbar, then power on target No. 1, set the target current to 120A, the bias to -80V, and the deposition time to 1260s, then cut off the current of target No. 1, power on target No. 3, set the target current to 160A, the bias to -80V, and the deposition time to 660s, and repeat the deposition cycle twice; or power on targets No. 1 and 3 at the same time, set the target currents to 120A and 160A respectively, set the bias to -80V, and the deposition time to 1560s;

[0025] S84, stop the nitrogen flow, and introduce argon into the chamber, and the pressure is stabilized at 1.6×10 -2 mbar, the column arc target is powered, the target current is set to 80A, the bias voltage is set to -300V, targets 2 and 3 are auxiliary anodes, the ion source current is 80A, and the etching time is 600s;

[0026] S85, stop the argon flow, and introduce nitrogen into the chamber, and the pressure is stabilized at 3.5×10 -2 mbar, then power on target No. 1, set the target current to 120A, the bias to -80V, and the deposition time to 1260s, then cut off the current of target No. 1, power on target No. 3, set the target current to 160A, the bias to -80V, and the deposition time to 660s, and repeat the deposition cycle twice; or power on targets No. 1 and 3 at the same time, set the target currents to 120A and 160A respectively, set the bias to -80V, and the deposition time to 1560s;

[0027] S86, stop the nitrogen flow, and introduce argon into the chamber, and the pressure is stabilized at 1.6×10 -2mbar, the column arc target is powered, the target current is set to 80A, the bias voltage is set to -300V, targets 2 and 3 are auxiliary anodes, the ion source current is 80A, and the etching time is 600s;

[0028] The target No. 2 and target No. 3 are auxiliary anodes;

[0029] The target material No. 1 is a Cr target, and the target material No. 3 is a Nb target.

[0030] Compared with existing technologies, the present invention demonstrates the following advantages: By introducing an argon ion etching step during the deposition of CrN / NbN multilayer / nanolayer coatings, the present invention interrupts the continuous growth of defects, reduces the density of through-hole defects typical of multilayer / nanolayer coatings, and lowers the coating surface roughness, resulting in the production of high-performance CrN / NbN coatings. This method, without the assistance of other equipment, adds an ion etching process, reducing through-hole defects in the coating and thereby improving the coating's electrochemical performance. Furthermore, the introduction of ion etching significantly improves the coating's surface defects and reduces coating roughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the ion etching process during the coating deposition process of the present invention;

[0032] Figure 2 Schematic diagram of the deposition of CrN / NbN multilayer / nano-multilayer coatings and the introduction of ion etching coatings according to the present invention: (a) CrN / NbN multilayer coating; (b) CrN / NbN multilayer coating + ion etching; (c) CrN / NbN nano-multilayer coating; (d) CrN / NbN nano-multilayer coating + ion etching;

[0033] Figure 3 Cross-sectional views of microscopic defects in CrN / NbN multilayer / nano-multilayer coatings and ion etching in accordance with an embodiment of the present invention: (a) CrN / NbN multilayer coating; (b) CrN / NbN multilayer coating + ion etching; (c) CrN / NbN nano-multilayer coating; (d) CrN / NbN nano-multilayer coating + ion etching;

[0034] Figure 4 Surface morphology and surface defect distribution of CrN / NbN multilayer / nano-multilayer coatings and coatings with ion etching according to the present invention: (a) CrN / NbN multilayer coating; (b) CrN / NbN multilayer coating + ion etching; (c) CrN / NbN nano-multilayer coating; (d) CrN / NbN nano-multilayer coating + ion etching;

[0035] Figure 5Two-dimensional morphology images of CrN / NbN multilayer / nano-multilayer coatings and coatings with ion etching according to embodiments of the present invention: (a) CrN / NbN multilayer coating; (b) CrN / NbN multilayer coating + ion etching; (c) CrN / NbN nano-multilayer coating; (d) CrN / NbN nano-multilayer coating + ion etching;

[0036] Figure 6 EIS test results of CrN / NbN multilayer / nano-multilayer coatings and ion-etched coatings in 3.5 wt% NaCl solution according to embodiments of the present invention: (a) CrN / NbN multilayer coating; (b) CrN / NbN multilayer coating + ion etching; (c) CrN / NbN nano-multilayer coating; (d) CrN / NbN nano-multilayer coating + ion etching. DETAILED DESCRIPTION

[0037] The above and other technical features and advantages of the present invention are described in more detail below with reference to the accompanying drawings.

[0038] Example 1

[0039] The surface of the φ25mm×8mm sample was polished with coarse sandpaper (80#) to remove rust, and then polished with fine sandpaper (240#, 400#, 600#, 800#, and 1000#). The sample surface was then polished to a mirror finish using 2.5μm polishing paste and a polishing cloth. Finally, the polished sample was ultrasonically cleaned in alcohol and then dried.

[0040] After the polished and cleaned sample is fixed with a fixture, it is placed on the turntable, the hatch of the PVD equipment is closed, and the mechanical pump, Roots pump and molecular pump are turned on in sequence to draw the vacuum to 5.0×10 -4 mbar, and then the heating program was turned on until the temperature in the chamber reached 300°C;

[0041] When the temperature in the chamber reaches 300°C, argon (Ar) is introduced into the chamber and the chamber pressure is stabilized at 1.2×10 - 2 mbar, set the bias voltage to -400 V, and perform glow cleaning on the sample surface for 600 s;

[0042] Then, argon (Ar) was continuously introduced into the chamber, and the chamber pressure was stabilized at 1.6×10 -2 mbar, set the bias voltage to -300V, start the column arc (Ti target), the target current is 80A, the current of the auxiliary anode ion source is 80A, the Ti ions sputtered from the target are blocked by the shield, and the generated electrons bombard and ionize the argon gas under the action of the auxiliary anode. The generated plasma etches and cleans the sample surface, enhancing the bonding strength between the sample and the coating. Figure 1 Schematic diagram of the ion etching device, which lasts for 1800s;

[0043] After the etching process is completed, Ar is continued to flow into the chamber, and the pressure in the chamber is stabilized at 3.5×10 -2 mbar, the bias voltage was adjusted to -100 V, target No. 1 was turned on, the target current was 100 A, and a Cr metal layer was deposited to improve the film-substrate bonding strength for 1800 s;

[0044] Then the argon gas was stopped and nitrogen was introduced into the chamber. The pressure in the chamber was stabilized at 3.5×10 -2 mbar, the bias voltage was set to -80V, the target No. 1 was powered on, the target current was adjusted to 120A, and the CrN coating was deposited for 1260s. Then the target No. 1 was turned off, the target No. 3 was powered on, the target current was set to 160A, and the NbN coating was deposited for 660s. Six cycles were repeated (as shown in the figure). Figure 2 (a));

[0045] After the coating process is completed, wait until the chamber temperature drops to 120°C, turn off the molecular pump, Roots pump and mechanical pump in sequence, inflate the chamber, open the door, take out the sample and air cool it to room temperature.

[0046] Example 2

[0047] The surface of the φ25mm×8mm sample was polished with coarse sandpaper (80#) to remove rust, and then polished with fine sandpaper (240#, 400#, 600#, 800#, and 1000#). The sample surface was then polished to a mirror finish using 2.5μm polishing paste and a polishing cloth. Finally, the polished sample was placed in alcohol for ultrasonic cleaning and then dried.

[0048] After the polished and cleaned sample is fixed with a fixture, it is placed on the turntable, the hatch of the PVD equipment is closed, and the mechanical pump, Roots pump and molecular pump are turned on in sequence to draw the vacuum to 5.0×10 -4 mbar, and then the heating program was turned on until the temperature in the chamber reached 300°C;

[0049] When the temperature in the chamber reaches 300°C, argon (Ar) is introduced into the chamber and the chamber pressure is stabilized at 1.2×10 - 2 mbar, set the bias voltage to -400 V, and perform glow cleaning on the sample surface for 600 s;

[0050] Then, argon (Ar) was continuously introduced into the chamber, and the chamber pressure was stabilized at 1.6×10 -2mbar, set the bias voltage to -300V, start the column arc (Ti target), the target current is 80A, the current of the auxiliary anode ion source is 80A, the Ti ions sputtered from the target are blocked by the shield, and the generated electrons bombard and ionize the argon gas under the action of the auxiliary anode. The generated plasma etches and cleans the sample surface, enhancing the bonding strength between the sample and the coating. Figure 1 Schematic diagram of the ion etching device, which lasts for 1800s;

[0051] After the etching process is completed, Ar is continued to flow into the chamber, and the pressure in the chamber is stabilized at 3.5×10 -2 mbar, the bias voltage was adjusted to -100 V, target No. 1 was turned on, the target current was 100 A, and a Cr metal layer was deposited to improve the film-substrate bonding strength for 1800 s;

[0052] Then the argon gas was stopped and nitrogen was introduced into the chamber. The pressure in the chamber was stabilized at 3.5×10 -2 mbar, the bias voltage was set to -80V, target No. 1 was powered on, the target current was adjusted to 120A, and the CrN coating was deposited for 1260s. Then target No. 1 was turned off, and target No. 3 was powered on, the target current was set to 160A, and the NbN coating was deposited for 660s. This cycle was repeated for two times.

[0053] Stop the nitrogen flow and introduce argon into the chamber. The pressure in the chamber is stabilized at 1.6×10 -2 mbar, the column arc target was powered on, the target current was set to 80A, the bias voltage was adjusted to -300V, targets 2 and 3 were used as auxiliary anodes, the ion source current was 80A, and the etching duration was 600s;

[0054] Stop the argon gas flow and introduce nitrogen into the chamber. The pressure in the chamber is stabilized at 3.5×10 -2 mbar, the bias voltage was set to -80V, target No. 1 was powered on, the target current was adjusted to 120A, and the CrN coating was deposited for 1260s. Then target No. 1 was turned off, and target No. 3 was powered on, the target current was set to 160A, and the NbN coating was deposited for 660s. This cycle was repeated for two times.

[0055] Stop the nitrogen flow and introduce argon into the chamber. The pressure in the chamber is stabilized at 1.6×10 -2 mbar, the column arc target was powered on, the target current was set to 80A, the bias voltage was adjusted to -300V, targets 2 and 3 were used as auxiliary anodes, the ion source current was 80A, and the etching duration was 600s;

[0056] Stop the argon gas flow and introduce nitrogen into the chamber. The pressure in the chamber is stabilized at 3.5×10 -2mbar, the bias voltage was set to -80V, target No. 1 was powered on, the target current was adjusted to 120A, and the CrN coating was deposited for 1260s. Then target No. 1 was turned off, and target No. 3 was powered on, the target current was set to 160A, and the NbN coating was deposited for 660s. This cycle was repeated for two times.

[0057] Stop the nitrogen flow and introduce argon into the chamber. The pressure in the chamber is stabilized at 1.6×10 -2 mbar, the arc target is powered, the target current is set to 80A, the bias voltage is adjusted to -300V, targets 2 and 3 are auxiliary anodes, the ion source current is 80A, and the etching duration is 600s (such as Figure 2 (b));

[0058] After the coating process is completed, wait until the chamber temperature drops to 120°C, turn off the molecular pump, Roots pump and mechanical pump in sequence, inflate the chamber, open the door, take out the sample and air cool it to room temperature.

[0059] Example 3

[0060] The surface of the φ25mm×8mm sample was polished with coarse sandpaper (80#) to remove rust, and then polished with fine sandpaper (240#, 400#, 600#, 800#, and 1000#). The sample surface was then polished to a mirror finish using 2.5μm polishing paste and a polishing cloth. Finally, the polished sample was ultrasonically cleaned in alcohol and then dried.

[0061] After the polished and cleaned sample is fixed with a fixture, it is placed on the turntable, the hatch of the PVD equipment is closed, and the mechanical pump, Roots pump and molecular pump are turned on in sequence to draw the vacuum to 5.0×10 -4 mbar, and then the heating program was turned on until the temperature in the chamber reached 300°C;

[0062] When the temperature in the chamber reaches 300°C, argon (Ar) is introduced into the chamber and the chamber pressure is stabilized at 1.2×10 - 2 mbar, set the bias voltage to -400 V, and perform glow cleaning on the sample surface for 600 s;

[0063] Then, argon (Ar) was continuously introduced into the chamber, and the chamber pressure was stabilized at 1.6×10 -2 mbar, set the bias voltage to -300V, start the column arc (Ti target), the target current is 80A, the current of the auxiliary anode ion source is 80A, the Ti ions sputtered from the target are blocked by the shield, and the generated electrons bombard and ionize the argon gas under the action of the auxiliary anode. The generated plasma etches and cleans the sample surface, enhancing the bonding strength between the sample and the coating. Figure 1Schematic diagram of the ion etching device, which lasts for 1800s;

[0064] After the etching process is completed, Ar is continued to flow into the chamber, and the pressure in the chamber is stabilized at 3.5×10 -2 mbar, the bias voltage was adjusted to -100 V, target No. 1 was turned on, the target current was 100 A, and a Cr metal layer was deposited to improve the film-substrate bonding strength for 1800 s;

[0065] Then the argon gas was stopped and nitrogen was introduced into the chamber. The pressure in the chamber was stabilized at 3.5×10 -2 mbar, the bias voltage was set to -80 V, and the No. 1 and No. 3 targets were powered with target currents of 120 A and 160 A, respectively, to deposit the CrN / NbN nano-multilayer coating for 4680 s (e.g. Figure 2 (c));

[0066] After the coating process is completed, wait until the chamber temperature drops to 120°C, turn off the molecular pump, Roots pump and mechanical pump in sequence, inflate the chamber, open the door, take out the sample and air cool it to room temperature.

[0067] Example 4

[0068] The surface of the φ25mm×8mm sample was polished with coarse sandpaper (80#) to remove rust, and then polished with fine sandpaper (240#, 400#, 600#, 800#, and 1000#). The sample surface was then polished to a mirror finish using 2.5μm polishing paste and a polishing cloth. Finally, the polished sample was placed in alcohol for ultrasonic cleaning and then dried.

[0069] After the polished and cleaned sample is fixed with a fixture, it is placed on the turntable, the hatch of the PVD equipment is closed, and the mechanical pump, Roots pump and molecular pump are turned on in sequence to draw the vacuum to 5.0×10 -4 mbar, and then the heating program was turned on until the temperature in the chamber reached 300°C;

[0070] When the temperature in the chamber reaches 300°C, argon (Ar) is introduced into the chamber and the chamber pressure is stabilized at 1.2×10 - 2 mbar, set the bias voltage to -400 V, and perform glow cleaning on the sample surface for 600 s;

[0071] Then, argon (Ar) was continuously introduced into the chamber, and the chamber pressure was stabilized at 1.6×10 -2mbar, set the bias voltage to -300V, start the column arc (Ti target), the target current is 80A, the current of the auxiliary anode ion source is 80A, the Ti ions sputtered from the target are blocked by the shield, and the generated electrons bombard and ionize the argon gas under the action of the auxiliary anode. The generated plasma etches and cleans the sample surface, enhancing the bonding strength between the sample and the coating. Figure 1 Schematic diagram of the ion etching device, which lasts for 1800s;

[0072] After the etching process is completed, Ar is continued to flow into the chamber, and the pressure in the chamber is stabilized at 3.5×10 -2 mbar, the bias voltage was adjusted to -100 V, target No. 1 was turned on, the target current was 100 A, and a Cr metal layer was deposited to improve the film-substrate bonding strength for 1800 s;

[0073] Then continue to introduce nitrogen into the chamber, and the pressure in the chamber is stabilized at 3.5×10 -2 mbar, the bias voltage was set to -80 V, and targets No. 1 and No. 3 were powered with target currents of 120 A and 160 A, respectively, for a duration of 1560 s;

[0074] Stop the nitrogen flow and introduce argon into the chamber. The pressure in the chamber is stabilized at 1.6×10 -2 mbar, the column arc target was powered on, the target current was set to 80A, the bias voltage was adjusted to -300V, targets 2 and 3 were used as auxiliary anodes, the ion source current was 80A, and the etching duration was 600s;

[0075] Stop the argon gas flow and introduce nitrogen into the chamber. The pressure in the chamber is stabilized at 3.5×10 -2 mbar, the bias voltage was set to -80 V, and targets No. 1 and No. 3 were powered with target currents of 120 A and 160 A, respectively, for a duration of 1560 s;

[0076] Stop the nitrogen flow and introduce argon into the chamber. The pressure in the chamber is stabilized at 1.6×10 -2 mbar, the column arc target was powered on, the target current was set to 80A, the bias voltage was adjusted to -300V, targets 2 and 3 were used as auxiliary anodes, the ion source current was 80A, and the etching duration was 600s;

[0077] Stop the argon gas flow and introduce nitrogen into the chamber. The pressure in the chamber is stabilized at 3.5×10 -2 mbar, the bias voltage is set to -80V, and the No. 1 and No. 3 targets are powered with target currents of 120A and 160A respectively, for a duration of 1560s (e.g. Figure 2 );

[0078] Stop the nitrogen flow and introduce argon into the chamber. The pressure in the chamber is stabilized at 1.6×10 -2 mbar, the arc target is powered, the target current is set to 80A, the bias voltage is adjusted to -300V, targets 2 and 3 are auxiliary anodes, the ion source current is 80A, and the etching duration is 600s (such as Figure 2 (d));

[0079] After the coating process is completed, wait until the chamber temperature drops to 120°C, turn off the molecular pump, Roots pump and mechanical pump in sequence, inflate the chamber, open the door, take out the sample and air cool it to room temperature.

[0080] 1. Micromorphology of the CrN / NbN multilayer coating prepared in Example 1, the CrN / NbN multilayer coating prepared by ion etching in Example 2, the CrN / NbN nano-multilayer coating in Example 3, and the CrN / NbN nano-multilayer coating prepared by ion etching in Example 4

[0081] The cross-sectional images of the deposited samples were taken using a field emission scanning electron microscope. Figure 3 The cross-sectional morphology of the CrN / NbN multilayer / nano-multilayer coating and the CrN / NbN multilayer / nano-multilayer coating after the introduction of intermediate ion etching. Figure 3 (b) and Figure 3 (d) It can be seen that the growth of metal particles in the coating is interrupted by the bombardment of Ar ions. This proves that Ar ion etching has the effect of interrupting the continuous growth of metal particles and smoothing the surface / interface.

[0082] The coating surface morphology was photographed using an optical microscope, and the defect area and distribution ratio of the coating surface were calculated using Image Pro software. The results are as follows: Figure 4 Table 1 shows the ratio of coating surface defects to the total area of ​​the region. As can be seen from the table, after the introduction of the ion etching process, the proportion of coating surface defects decreased, and ion etching treatment can improve coating surface defects.

[0083] Table 1 Surface defect area values ​​of the coatings obtained in Examples 1 to 4 after processing with Image Pro Plus software

[0084]

[0085] The two-dimensional morphology of the coating surface was measured using a profilometer. The results are as follows: Figure 5 At the same time, the surface profiles of three different locations of the coating were randomly selected and the average roughness and standard deviation of the coating surface were calculated based on the results. The results are shown in Table 2. As can be seen from the table, the surface roughness of the coating is reduced after the ion etching step is introduced, which is consistent with the Figure 4Consistent with the conclusion in Table 1, this is mainly attributed to the fact that the ion etching process can effectively hinder the continuous growth of defects such as metal particles and has a certain smoothing effect on the coating surface or interface.

[0086] Table 2 Surface roughness of coatings obtained in Examples 1 to 4

[0087]

[0088] II. Performance Tests of the CrN / NbN Multilayer Coating Prepared in Example 1, the CrN / NbN Multilayer Coating Introduced by Ion Etching in Example 2, the CrN / NbN Nano-Multilayer Coating in Example 3, and the CrN / NbN Nano-Multilayer Coating Introduced by Ion Etching in Example 4

[0089] The electrochemical impedance spectroscopy (EIS) of the coating was tested. Figure 6 The data of AC impedance spectrum was fitted and the results are shown in Table 3. The R po The value is greater than that of the coating sample without ion etching, which shows that the addition of the ion etching step can effectively reduce the number of defects in the coating and slow down the rate of electrolyte penetration into the substrate along the coating defects. ct It is considered to be an important indicator for evaluating the corrosion resistance of coatings. Comparing CrN / NbN multilayer / nano-multilayer coatings and CrN / NbN multilayer / nano-multilayer coatings with ion etching, it can be seen that after adding the ion etching process, the R ct The increase in the value indicates that the electrochemical corrosion resistance of the coating is improved.

[0090] Table 3 AC impedance spectrum fitting results of the coatings obtained in Examples 1 to 4 in 3.5 wt.% NaCl solution

[0091]

[0092] In summary, the CrN / NbN multilayer / nano-multilayer coatings prepared by the present invention effectively reduce the defect density of the multilayer / nano-multilayer coatings by introducing an ion etching process step. The microstructure of the coatings before and after ion etching was analyzed, and the corrosion electrochemical properties of the different coatings in 3.5 wt.% NaCl solution were further analyzed. The results show that the introduction of ion etching reduced the defect density of the coatings and improved the electrochemical properties of the coatings. These results indicate that the introduction of ion etching is an effective strategy to further enhance the corrosion resistance of workpieces in service in marine environments.

[0093] The above description is merely a preferred embodiment of the present invention and is intended to be illustrative rather than restrictive of the present invention. Those skilled in the art will appreciate that many changes, modifications, and even equivalents may be made to the present invention within the spirit and scope of the claims, all of which fall within the scope of protection of the present invention.

Claims

1. A method for controlling defects in PVD deposited coatings using an ion etching process, characterized in that: The following steps are involved: S1, sample surface pretreatment: Use coarse sandpaper to grind and remove rust from the sample surface, then use fine sandpaper to polish the surface, and then use polishing equipment to polish the sample surface to a mirror surface. Finally, put the polished sample into alcohol for ultrasonic cleaning and drying; S2, clamping the sample: After fixing the surface pre-treated sample with a clamp, place it on the rotating rack in the furnace chamber; S3, vacuum the equipment: pump the pressure in the chamber to P ≤ ; S4, equipment heating: the sample is heated to 300 °C by the heating tube on the wall of the equipment cavity, and the heating time is 3600 s; S5, glow cleaning of the sample: argon gas was introduced into the chamber, the bias voltage was set to -400 V, and the sample surface was glow cleaned; S6, ion etching and cleaning of the sample: Argon gas is introduced into the chamber, the bias voltage is set to -300 V, and the Ti target is turned on. The Ti ions sputtered from the target are blocked by the shielding cover, and the generated electrons bombard and ionize the argon gas under the action of the auxiliary anode. The generated plasma etches and cleans the sample surface; S7, deposition of a transition layer on the sample: After the sample is ion-etched and cleaned, argon gas is introduced into the chamber, and the Cr target is turned on. Particles sputtered from the target are deposited on the sample surface to form a Cr metal transition layer. S8, preparation of CrN / NbN coating: stop the argon flow, introduce nitrogen into the chamber, alternately turn on or simultaneously turn on the Cr target and Nb target arc power supplies, and the particles sputtered from the target and the particles ionized by the nitrogen gas combine to form a CrN / NbN multilayer / nano-multilayer coating. During the coating preparation process, three ion etchings are inserted, each lasting 600 s. S9, sample cooling and sampling: After deposition is completed, take out the sample when the furnace chamber temperature cools down to below 120°C; In step S8, nitrogen is introduced and the pressure in the chamber is stabilized at , the current of Cr target is 120 A, the current of Nb target is 160 A, and the substrate bias is -80 V; In step S8, the specific process is as follows: S81, stop the argon gas flow, and introduce nitrogen into the chamber, and the pressure is stabilized at , then power on target No. 1, set the target current to 120 A, the bias voltage to -80 V, and the deposition time to 1260 s, then cut off the current of target No. 1, power on target No. 3, set the target current to 160 A, the bias voltage to -80 V, and the deposition time to 660 s, and perform two alternating deposition cycles; or power on targets No. 1 and No. 3 at the same time, set the target currents to 120 A and 160 A respectively, set the bias voltage to -80 V, and the deposition time to 1560 s; S82, stop the nitrogen flow, and introduce argon into the chamber until the pressure stabilizes at , the column arc target is powered on, the target current is set to 80 A, the bias voltage is set to -300 V, targets 2 and 3 are auxiliary anodes, the ion source current is 80 A, and the etching time is 600 s; S83, stop the argon gas flow, and introduce nitrogen into the chamber until the pressure is stabilized at , then power on target No. 1, set the target current to 120 A, the bias voltage to -80 V, and the deposition time to 1260 s, then cut off the current of target No. 1, power on target No. 3, set the target current to 160 A, the bias voltage to -80 V, and the deposition time to 660 s, and perform two alternating deposition cycles; or power on targets No. 1 and No. 3 at the same time, set the target currents to 120 A and 160 A respectively, set the bias voltage to -80 V, and the deposition time to 1560 s; S84, stop the nitrogen flow, and introduce argon into the chamber, and the pressure is stabilized at , the column arc target is powered on, the target current is set to 80 A, the bias voltage is set to -300 V, targets 2 and 3 are auxiliary anodes, the ion source current is 80 A, and the etching time is 600 s; S85, stop the argon gas flow, and introduce nitrogen into the chamber until the pressure stabilizes at , then power on target No. 1, set the target current to 120 A, the bias voltage to -80 V, and the deposition time to 1260 s, then cut off the current of target No. 1, power on target No. 3, set the target current to 160 A, the bias voltage to -80 V, and the deposition time to 660 s, and perform two alternating deposition cycles; or power on targets No. 1 and No. 3 at the same time, set the target currents to 120 A and 160 A respectively, set the bias voltage to -80 V, and the deposition time to 1560 s; S86, stop the nitrogen flow, and introduce argon into the chamber until the pressure stabilizes at , the column arc target is powered on, the target current is set to 80 A, the bias voltage is set to -300 V, targets 2 and 3 are auxiliary anodes, the ion source current is 80 A, and the etching time is 600 s; The target No. 2 and target No. 3 are auxiliary anodes; The target material No. 1 is a Cr target, and the target material No. 3 is a Nb target.

2. The method for controlling defects in PVD deposited coatings by an ion etching process according to claim 1, wherein: In step S6, argon gas is introduced to stabilize the pressure in the chamber. , the bias voltage is -300 V, and the current of the Ti target is 80 A.

3. The method for controlling defects in PVD deposited coatings by ion etching process according to claim 1, wherein: In step S6, the duration of etching and cleaning is 1800 s.

4. The method for controlling defects in PVD deposited coatings by an ion etching process according to claim 1, wherein: In step S7, argon gas is introduced to stabilize the pressure in the chamber. , the current of Cr target is 100 A.

Images