A neodymium-iron-boron magnet rare earth permeation method based on laser nano-etching and plasma synergistic pretreatment

Abstract

This invention discloses a rare earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment, comprising the following steps: S1: NdFeB magnet loading and positioning; S2: Ablation cleaning and activation of the NdFeB magnet surface using argon plasma; S3: Nano-etching patterns on the NdFeB magnet surface using picosecond or femtosecond lasers in a pulsed dot matrix pattern; S4: Weak acid etching of the NdFeB magnet surface to remove the heat-affected layer and open grain boundary diffusion channels; S5: Rare earth infiltration of NdFeB magnets using laser nano-micro etching and plasma synergistic pretreatment. S6: Magnetron sputtering deposition of Tb thin film on the surface of NdFeB magnet; S7: Annealing and diffusion of NdFeB magnet in vacuum or inert atmosphere to form a shell-rich Tb grain boundary structure; S8: Post-processing and quality assessment of NdFeB magnet significantly improves the adhesion and interface stability of magnet surface deposition; penetration depth is increased to more than twice that of traditional planar treatment; Tb content is reduced by 30-50% while maintaining or improving Hcj coercivity; grain boundary penetration uniformity is improved, and thermal stability and demagnetization resistance are enhanced.

Description

Technical Field

[0001] This invention relates to the technical field of surface treatment of rare earth permanent magnet materials, and in particular to a rare earth infiltration method for neodymium iron boron magnets based on laser nano-micro etching and plasma synergistic pretreatment. Background Technology

[0002] In the preparation of NdFeB magnets, doping with heavy rare earth elements such as dysprosium or terbium can improve the crystal structure, forming the Dy2Fe14B or Tb2Fe14B phase, thereby improving the magnet's performance. Grain boundary penetration technology is a technique that can improve the coercivity of NdFeB magnets. This technique involves first attaching a layer of heavy rare earth elements such as dysprosium or terbium to the surface of the NdFeB matrix, and then using heat treatment and tempering processes to allow the attached heavy rare earth elements to penetrate into the interior of the magnet through the grain boundaries, thereby increasing the Nd2Fe14B phase. This improves the magnet's coercivity without reducing its remanence.

[0003] Chinese patent application number CN201710130288.8 discloses a method for preparing high coercivity NdFeB magnets by grain boundary diffusion. The process steps are as follows: first, the surface of the NdFeB magnet is cleaned; then, the magnet is preheated under vacuum; then, it is immersed in a vacuum-melted metal or alloy melt for hot-dip coating to achieve surface coating; finally, the hot-dip coated NdFeB magnet is subjected to diffusion heat treatment and subsequent annealing treatment to improve the boundary structure and grain boundary phase distribution of the magnet, thereby obtaining the desired high coercivity NdFeB magnet. However, the method still has shortcomings, such as low Tb deposition efficiency, limited penetration depth, large dosage, and poor uniformity.

[0004] Chinese patent application number CN200810179949.7 discloses a rare earth permanent magnet and its preparation method. The method involves arranging easily pulverized alloy powder on the surface of a sintered NdFeB magnet. The alloy powder is a rare earth intermetallic compound. The heat treatment temperature is 20℃~(Ts-10)℃, where Ts is the sintering temperature of the sintered magnet. The sintered magnet includes a minimum part equal to or less than 20 mm. However, the method still has shortcomings. For sintered NdFeB magnets, the diffusion depth of the current grain boundary penetration technology is limited. Heavy rare earth elements cannot diffuse into the interior of larger magnets. The method also has strict requirements on sample size and can generally only process thin sheet magnets.

[0005] Existing methods for Tb infiltration into NdFeB magnets generally rely on a deposition-annealing diffusion path. However, due to the low surface activity of the magnets, poor interfacial bonding, and limited channels in the grain boundary structure, the Tb deposition efficiency is low, the penetration depth is limited, the amount used is large, and the uniformity is poor. Conventional pretreatment methods cannot meet the requirements for micro-nano-scale structure control of NdFeB magnets. Summary of the Invention

[0006] The purpose of this invention is to solve the problems in the prior art and propose a rare earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment. This method can increase the specific surface area and open the grain boundary channels on the surface of NdFeB magnets, effectively improve the adhesion of rare earth deposited films and subsequent infiltration efficiency, thereby achieving excellent magnetic performance enhancement while reducing the amount of Tb raw materials used.

[0007] To achieve the above objectives, this invention proposes a rare-earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment, comprising the following steps: S1: Neodymium iron boron magnet loading and positioning; S2: Argon plasma is used to ablate, clean, and activate the surface of neodymium iron boron magnets; S3: Use picosecond or femtosecond lasers to etch nano-scale patterns on the surface of neodymium iron boron magnets in a pulsed dot matrix format; S4: The surface of the NdFeB magnet is subjected to weak acid etching to remove the heat-affected layer and open the grain boundary diffusion channel; S5: Magnetron sputtering deposition of a Tb thin film on the surface of a NdFeB magnet; S6: Place the neodymium iron boron magnet in a vacuum or inert atmosphere for annealing and diffusion to form a shell-like Tb-rich grain boundary structure; S7: Post-processing and quality assessment of neodymium iron boron magnets.

[0008] Preferably, the neodymium iron boron magnet loading and positioning in step S1 includes the following steps: S1-1: The neodymium iron boron magnets are arranged and fed using an automatic vibratory feeder. S1-2: Positioning, clamping and fixing the neodymium iron boron magnets that are arranged and fed; S1-3: Dust removal and cleaning of neodymium iron boron magnets: After blowing with compressed air or ultrasonic deionized water cleaning, dry them at a temperature ≤ 120 ℃.

[0009] Preferably, in step S2, the positioned NdFeB magnet is transported to an airtight plasma treatment chamber, evacuated to the base pressure, and then high-purity Ar with a purity greater than 99.99% is introduced and ignited to perform ablation cleaning and activation treatment on the surface of the NdFeB magnet. The frequency is 13.56 MHz; the power is 100-300 W; the chamber pressure is 30-60 Pa; the Ar flow rate is 30-100 sccm; the treatment time is 120-600 s; the workpiece temperature rise is controlled to be ≤60 ℃; after the treatment, the Ar atmosphere is maintained for cooling for 10-60 s.

[0010] Preferably, in step S2, when there is a significant oxide layer on the surface of the neodymium iron boron magnet, a two-stage surface treatment mode of "low-power pretreatment + high-power main treatment" is adopted.

[0011] Preferably, in step S3, the surface-activated NdFeB magnet is guided to a laser micro-etching workstation. Picosecond or femtosecond lasers are used to etch one or more patterns of hexagonal micro-holes, interlaced micro-grooves, and random micro-pits onto the surface of the NdFeB magnet using a pulsed dot matrix pattern with single-shot, repeated dot matrix stacking, or multiple shallow machining stacking. Inert gas is introduced for purging during the process. Laser wavelength: 355 nm / 532 nm / 1064 nm; pulse width-femtosecond: 100–300 fs; pulse width-picosecond: 5–15 ps; repetition frequency: 50–200 kHz; single pulse energy: 0.5–10 μJ; focused spot diameter: 0.5–1.0 μm; scanning speed: 100–800 mm / s; dot matrix spacing / line spacing: 0.8–1.5 μm; machining depth: 80–200 nm; feature size: hole diameter / groove width / pit diameter 0.4–0.9. μm.

[0012] Preferably, in step S4, the pH of the acid solution for weak acid etching is controlled at 2.5-4.0; the temperature is 15-40℃; the time is 30-90s; during the weak acid etching process, low-speed stirring or ultrasonic cleaning at 20-60kHz is used for assisted cleaning; after weak acid etching, deionized water is used for rinsing for 30-120s; after rinsing with deionized water, nitrogen is used for drying and drying at 60-120℃ for 5-20min.

[0013] Preferably, in step S5, the acid-washed and dried NdFeB magnet is sent into the magnetron sputtering cavity, and a vacuum is drawn to the substrate vacuum. Low-power Ar plasma sputtering cleaning is performed in the magnetron sputtering cavity for 30-120 s to remove adsorbed water and residual contaminants. The sputtering gas has an Ar purity greater than 99.99%; the working pressure is 0.3-1.0 Pa; the sputtering power is 100-300 W; the target-substrate distance is 70-120 mm; the substrate temperature is 25-120 °C; the deposition rate is 0.5-10 nm / min; and the film thickness is 150-200 nm.

[0014] Preferably, in step S6, the atmosphere is: vacuum ≤ 1×10⁻⁶ -2 Pa or an inert atmosphere of Ar / N2 with oxygen content ≤ 50ppm; heating rate: 3-10℃ / min; annealing temperature: 750-900℃; holding time: 30-120 min; cooling method: furnace cooling or controlled cooling ≤10℃ / min.

[0015] Preferably, the post-processing and quality assessment of the NdFeB magnet in step S7 includes the following steps: S7-1: Surface cleaning: Ultrasonic cleaning of neodymium iron boron magnets with deionized water or anhydrous ethanol for 1-5 minutes to remove residual particles; S7-2: Magnetic property tests: Br, Hcj, (BH)max, with a focus on testing the improvement of Hcj; S7-3: Composition / Penetration Depth: Cross-sectional SEM+EDS line scan or area scan, statistical analysis of Tb penetration depth D and uniformity; S7-4: Adhesion: Cross-cut / tape method or micro / nano indentation peel test; S7-5: Judgment: When the Tb penetration depth is ≥ 1.5-2.5 times that of the traditional process and the Hcj increase is ≥ 20%, it is judged as effective.

[0016] The beneficial effects of this invention are as follows: This invention utilizes a synergistic pretreatment of "plasma ablation activation + laser nano-etching." Plasma is used to remove surface oxide layers / organic contaminants, improve surface energy and wettability, and enhance the consistency and adhesion of subsequent laser processing. Laser nano-etching constructs submicron characteristic structures on the surface, increasing the specific surface area and forming controllable microchannels / microtraps, enabling the Tb film to achieve higher mechanical interlocking and a larger effective diffusion interface within the microstructure. Laser processing inevitably produces localized heat-affected layers, re-solidified layers, microcrack sealing areas, or surface re-oxidation layers. This invention addresses these issues by using pH... Short-term treatment with 2-5 weak acids selectively removes the heat-affected layer generated by laser processing and forms micro-openings at grain boundaries. This allows the Tb film to form mechanical intercalation on the microstructure surface, enhancing the interfacial bonding strength. During the subsequent annealing stage, rapid, deep, and uniform penetration and diffusion are achieved along the grain boundary channels. This significantly improves coercivity and thermal stability while reducing the amount of Tb used. It also makes Tb more likely to migrate along the grain boundaries during the annealing diffusion stage, significantly improving penetration depth and uniformity. It significantly improves the adhesion and interfacial stability of magnet surface deposition. The penetration depth is increased to more than twice that of traditional planar treatment. The amount of Tb used is reduced by 30-50% while maintaining or improving Hcj coercivity. It also improves grain boundary penetration uniformity, thermal stability, and demagnetization resistance.

[0017] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a flowchart of a rare earth infiltration method for neodymium iron boron magnets based on laser nano-micro etching and plasma synergistic pretreatment, according to the present invention. Detailed Implementation

[0019] See Figure 1 This invention discloses a rare earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment, comprising the following steps: S1: Neodymium iron boron magnet loading and positioning; S2: Argon plasma is used to ablate, clean, and activate the surface of neodymium iron boron magnets; S3: Use picosecond or femtosecond lasers to etch nano-scale patterns on the surface of neodymium iron boron magnets in a pulsed dot matrix format; S4: The surface of the NdFeB magnet is subjected to weak acid etching to remove the heat-affected layer and open the grain boundary diffusion channel; S5: Magnetron sputtering deposition of a Tb thin film on the surface of a NdFeB magnet; S6: Place the neodymium iron boron magnet in a vacuum or inert atmosphere for annealing and diffusion to form a shell-like Tb-rich grain boundary structure; S7: Post-processing and quality assessment of neodymium iron boron magnets.

[0020] The neodymium iron boron magnet loading and positioning in step S1 includes the following steps: S1-1: The neodymium iron boron magnets are arranged and fed using an automatic vibratory feeder. S1-2: Positioning, clamping and fixing the neodymium iron boron magnets that are arranged and fed; S1-3: Dust removal and cleaning of neodymium iron boron magnets: After blowing with compressed air or ultrasonic deionized water cleaning, dry them at a temperature ≤ 120 ℃; In step S2, the positioned NdFeB magnet is transported to an airtight plasma treatment chamber, evacuated to the base pressure, and then high-purity Ar with a purity greater than 99.99% is introduced and ignited to perform ablation cleaning and activation treatment on the surface of the NdFeB magnet. Frequency: 13.56 MHz; Power: 100-300 W; Chamber pressure: 30-60 Pa; Ar flow rate: 30-100 sccm; Processing time: 120-600 s; Workpiece temperature rise control: surface temperature ≤60 ℃; After processing, maintain Ar atmosphere for cooling for 10-60 s. In step S2, when there is a significant oxide layer on the surface of the neodymium iron boron magnet, a two-stage surface treatment mode of "low-power pretreatment + high-power main treatment" is adopted. In step S3, the surface-activated NdFeB magnet is guided to a laser micro-etching workstation. Picosecond or femtosecond lasers are used to etch one or more patterns on the NdFeB magnet surface, including hexagonal micro-holes, interlaced micro-grooves, and random micro-pits, using a pulsed dot matrix pattern with single-shot, repeated dot matrix stacking, or multiple shallow machining stacking. Inert gas is introduced for purging during the process. Laser wavelength: 355 nm / 532 nm / 1064 nm; pulse width-femtosecond: 100–300 fs; pulse width-picosecond: 5–15 ps; repetition frequency: 50–200 kHz; single pulse energy: 0.5–10 μJ; focused spot diameter: 0.5–1.0 μm; scanning speed: 100–800 mm / s; dot matrix spacing / line spacing: 0.8–1.5 μm; machining depth: 80–200 nm; feature dimensions: hole diameter / groove width / pit diameter 0.4–0.9 μm. In step S4, the pH of the acid solution for weak acid etching is controlled at 2.5-4.0; the temperature is 15-40℃; the time is 30-90s; during the weak acid etching process, low-speed stirring or ultrasonic cleaning at 20-60kHz is used for assisted cleaning; after weak acid etching, deionized water is used for rinsing for 30-120s; after rinsing with deionized water, nitrogen is used for drying and drying at 60-120℃ for 5-20min. In step S5, the acid-washed and dried NdFeB magnet is placed into the magnetron sputtering cavity, and a vacuum is drawn to the substrate vacuum. Low-power Ar plasma sputtering is then performed in the magnetron sputtering cavity for 30-120 seconds to remove adsorbed water and residual contaminants. The sputtering gas has an Ar purity greater than 99.99%; operating pressure is 0.3-1.0 Pa; sputtering power is 100-300 W; target-substrate distance is 70-120 mm; substrate temperature is 25-120 °C; deposition rate is 0.5-10 nm / min; and film thickness is 150-200 nm. In step S6, the atmosphere is: vacuum ≤ 1×10⁻⁶ -2 Pa or an inert atmosphere of Ar / N2 with oxygen content ≤ 50ppm; heating rate: 3-10℃ / min; annealing temperature: 750-900℃; holding time: 30-120 min; cooling method: furnace cooling or controlled cooling ≤10℃ / min; The post-processing and quality assessment of the neodymium iron boron magnet in step S7 includes the following steps: S7-1: Surface cleaning: Ultrasonic cleaning of neodymium iron boron magnets with deionized water or anhydrous ethanol for 1-5 minutes to remove residual particles; S7-2: Magnetic property tests: Br, Hcj, (BH)max, with a focus on testing the improvement of Hcj; S7-3: Composition / Penetration Depth: Cross-sectional SEM+EDS line scan or area scan, statistical analysis of Tb penetration depth D and uniformity; S7-4: Adhesion: Cross-cut / tape method or micro / nano indentation peel test; S7-5: Judgment: When the Tb penetration depth is ≥ 1.5-2.5 times that of the traditional process and the Hcj increase is ≥ 20%, it is judged as effective.

[0021] Example of Tb permeation diffusion using a hexagonal micropore + staggered microgroove combination structure: Select a sintered NdFeB magnet with dimensions of 10×10×5 mm³ and process it according to the following steps: (1) Plasma activation: The neodymium iron boron magnet was placed in the airtight plasma treatment chamber, and Ar gas was introduced after evacuation. The chamber pressure was stabilized at 50 Pa. 13.56 MHz radio frequency plasma was used with a power of 200 W for 600 s. After treatment, it was cooled in Ar atmosphere for 30 s. (2) Laser nano-micro etching: A 532 nm femtosecond laser with a pulse width of <300 fs, a repetition frequency of 100 kHz, and a focused spot diameter of 0.8 μm is used to process a combination structure of hexagonal hole array and staggered groove array in a pulse dot matrix manner, wherein the hole diameter is 0.6 μm, the hole spacing is 1.2 μm, the groove width is 0.8 μm, and the etching depth is controlled at 100-150 nm; (3) Weak acid etching: The laser-treated NdFeB magnets were immediately immersed in a dilute nitric acid-citric acid composite solution with pH=2 for 60s, then rinsed with deionized water for 60s and dried with nitrogen gas, and finally dried at 80℃ for 10 min. (4) Tb magnetron sputtering: Place the NdFeB magnet into the magnetron sputtering cavity and evacuate to a substrate vacuum ≤1×10 - 3 Pa, Ar gas was introduced and the working pressure was stabilized at 0.5 Pa, and Tb thin film was deposited by Tb target sputtering with a film thickness of 200 nm; (5) Annealing diffusion: The deposited sample is placed in a vacuum furnace with a vacuum degree ≤1×10 -2 Pa, heated to 800℃, held for 90 minutes, then furnace cooled.

[0022] Cross-sectional SEM and EDS analysis showed that Tb penetrated to a depth of ≥2.8 μm along the grain boundaries and was uniformly distributed. Magnetic property tests showed that the coercivity Hcj was increased by about 28%, and the Tb deposition thickness could be reduced by about 45% to achieve the same Hcj increase target.

[0023] This invention significantly improves the adhesion and interface stability of magnet surface deposition; increases the penetration depth to more than twice that of traditional planar treatment; reduces Tb dosage by 30-50% while maintaining or increasing Hcj coercivity; improves grain boundary penetration uniformity; and enhances thermal stability and demagnetization resistance.

[0024] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the scope of protection of the present invention.

Claims

1. A rare earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment, characterized in that: Includes the following steps: S1: Neodymium iron boron magnet loading and positioning; S2: Argon plasma is used to ablate, clean, and activate the surface of neodymium iron boron magnets; S3: Use picosecond or femtosecond lasers to etch nano-scale patterns on the surface of neodymium iron boron magnets in a pulsed dot matrix format; S4: The surface of the NdFeB magnet is subjected to weak acid etching to remove the heat-affected layer and open the grain boundary diffusion channel; S5: Magnetron sputtering deposition of a Tb thin film on the surface of a NdFeB magnet; S6: Place the neodymium iron boron magnet in a vacuum or inert atmosphere for annealing and diffusion to form a shell-like Tb-rich grain boundary structure; S7: Post-processing and quality assessment of neodymium iron boron magnets.

2. The rare earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment as described in claim 1, characterized in that: The neodymium iron boron magnet loading and positioning in step S1 includes the following steps: S1-1: The neodymium iron boron magnets are arranged and fed using an automatic vibratory feeder. S1-2: Positioning, clamping and fixing the neodymium iron boron magnets that are arranged and fed; S1-3: Dust removal and cleaning of neodymium iron boron magnets: After blowing with compressed air or ultrasonic deionized water cleaning, dry them at a temperature ≤ 120 ℃.

3. The rare earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment as described in claim 1, characterized in that: In step S2, the positioned neodymium iron boron magnet is transported to the airtight plasma treatment chamber, and a vacuum is drawn to the base pressure. After vacuuming, high-purity Ar with a purity greater than 99.99% is introduced and ignited to perform ablation cleaning and activation treatment on the surface of the neodymium iron boron magnet. Frequency: 13.56 MHz. Power: 100-300 W; Chamber pressure: 30-60 Pa; Ar flow rate: 30-100 sccm; Processing time: 120-600 s; Workpiece temperature rise control: surface temperature ≤60 ℃; After processing, maintain Ar atmosphere for cooling for 10-60 s.

4. The rare earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment as described in claim 3, characterized in that: In step S2, when there is a significant oxide layer on the surface of the neodymium iron boron magnet, a two-stage surface treatment mode of "low-power pretreatment + high-power main treatment" is adopted.

5. The rare earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment as described in claim 1, characterized in that: In step S3, the surface-activated NdFeB magnet is guided to a laser micro-etching workstation. Picosecond or femtosecond lasers are used to etch one or more patterns on the NdFeB magnet surface, including hexagonal micro-holes, interlaced micro-grooves, and random micro-pits, using a pulsed dot matrix pattern with single-shot, repeated dot matrix stacking, or multiple shallow machining stacking. Inert gas is introduced for purging during the process. Laser wavelength: 355 nm / 532 nm / 1064 nm; pulse width-femtosecond: 100–300 fs; pulse width-picosecond: 5–15 ps; repetition frequency: 50–200 kHz; single pulse energy: 0.5–10 μJ; focused spot diameter: 0.5–1.0 μm; scanning speed: 100–800 mm / s; dot matrix spacing / line spacing: 0.8–1.5 μm; machining depth: 80–200 nm; feature dimensions: hole diameter / groove width / pit diameter 0.4–0.9 μm.

6. The rare earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment as described in claim 1, characterized in that: In step S4, the pH of the acid solution used for weak acid etching is controlled between 2.5 and 4.

0. Temperature: 15-40℃; Time: 30-90s; During the weak acid etching process, stir at low speed or use 20-60kHz ultrasonic cleaning; After weak acid etching, rinse with deionized water for 30-120s; After rinsing with deionized water, blow dry with nitrogen and dry at 60-120℃ for 5-20min.

7. The rare earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment as described in claim 1, characterized in that: In step S5, the acid-washed and dried NdFeB magnet is sent into the magnetron sputtering cavity, and a vacuum is drawn to the substrate vacuum. Low-power Ar plasma sputtering cleaning is performed in the magnetron sputtering cavity for 30-120 s to remove adsorbed water and residual contaminants. Sputtering gas: Ar purity greater than 99.99%; working pressure: 0.3-1.0 Pa; sputtering power: 100-300 W; target-substrate distance: 70-120 mm; substrate temperature: 25-120 °C; deposition rate: 0.5-10 nm / min; film thickness: 150-200 nm.

8. The rare earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment as described in claim 1, characterized in that: In step S6, the atmosphere is: vacuum ≤ 1×10⁻⁶ -2 Pa or an inert atmosphere of Ar / N2 with oxygen content ≤ 50ppm; heating rate: 3-10℃ / min; annealing temperature: 750-900℃; holding time: 30-120 min; cooling method: furnace cooling or controlled cooling ≤10℃ / min.

9. The rare earth infiltration method for NdFeB magnets based on laser nano-micro etching and plasma synergistic pretreatment as described in claim 1, characterized in that: The post-processing and quality assessment of the neodymium iron boron magnets in step S7 includes the following steps: S7-1: Surface cleaning: Ultrasonic cleaning of neodymium iron boron magnets with deionized water or anhydrous ethanol for 1-5 minutes to remove residual particles; S7-2: Magnetic property tests: Br, Hcj, (BH)max, with a focus on testing the improvement of Hcj; S7-3: Composition / Penetration Depth: Cross-sectional SEM+EDS line scan or area scan, statistical analysis of Tb penetration depth D and uniformity; S7-4: Adhesion: Cross-cut / tape method or micro / nano indentation peel test; S7-5: Judgment: When the Tb penetration depth is ≥ 1.5-2.5 times that of the traditional process and the Hcj increase is ≥ 20%, it is judged as effective.

Images