High-hardness DLC composite coating tempered film, preparation method thereof and application of high-hardness DLC composite coating tempered film in electronic screen protection

Abstract

The invention relates to the technical field of tempered films, in particular to a high-hardness DLC composite coating tempered film, a preparation method thereof and application of the high-hardness DLC composite coating tempered film in electronic screen protection, and the high-hardness DLC composite coating tempered film sequentially comprises a Cr / W nano gradient transition layer, a Si-DLC buffer layer, a W-DLC / B4C nano lamination layer and an FLC fullerene-like carbon layer from the surface of a substrate to the outside. According to the high-hardness DLC composite coating tempered film, the problem that the toughness of the coating is reduced due to the pursuit of high hardness of the high-hardness DLC composite coating tempered film is solved, and the adhesive force is also improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tempered film, in particular to a high-hardness DLC composite coating tempered film, a preparation method thereof and an application thereof in electronic screen protection. BACKGROUND

[0002] With the rapid development of electronic technology, various electronic devices such as smartphones, tablets, smartwatches have become an indispensable part of people's daily life. As the core interface of human-computer interaction, the performance and quality of the screen of electronic devices directly affect the user experience. However, the electronic screen is easily damaged by external forces such as scratching, collision, falling, etc. during use, resulting in scratches, cracks or even breakage on the screen, which not only affects the appearance of the device, but also reduces its display effect and service life, and may even cause safety hazards. Therefore, how to effectively protect the electronic screen and improve its wear resistance, scratch resistance and impact resistance has become an important problem to be solved in the current electronic device field.

[0003] As a new type of screen protection material, high-hardness DLC (diamond-like carbon) composite coating tempered film has gradually attracted widespread attention in the market due to its excellent mechanical properties and chemical stability. It combines the high hardness, low friction coefficient of DLC coating and the high strength characteristics of tempered film, and can effectively resist the scratching and impact of external objects, providing reliable protection for electronic screens.

[0004] High hardness is one of the important characteristics of DLC coating, but too high hardness often leads to a decrease in the toughness of the coating. In actual use, electronic screens may be subjected to different degrees of impact and bending, and if the toughness of the DLC coating is insufficient, cracks or even peeling may occur, thereby losing the protective effect on the screen. Currently, some high-hardness DLC composite coating tempered films pursue higher hardness by using thicker DLC coatings or special deposition processes, but this often sacrifices the toughness of the coating, making the product perform poorly in impact resistance. The adhesion between the DLC coating and the tempered film substrate is one of the key factors affecting the performance of the composite coating tempered film. Good adhesion can ensure that the DLC coating does not fall off during long-term use, thereby ensuring its protective effect. However, existing preparation methods often fail to ensure sufficient adhesion between the DLC coating and the substrate while improving the hardness of the DLC coating. This may be due to the combined effects of various factors such as the roughness, chemical composition of the tempered film surface and deposition process parameters. Unstable adhesion not only affects the service life of the product, but also may cause the coating to fall off when the screen is subjected to slight external forces, reducing the user experience. Based on this, the present application provides a high-hardness DLC composite coating tempered film, a preparation method thereof and an application thereof in electronic screen protection. SUMMARY

[0005] The application aims to provide a high-hardness DLC composite coating tempered film, a preparation method thereof and an application in electronic screen protection, which improves the problem that the high-hardness DLC composite coating tempered film is prone to cracks or even peeling when the electronic screen is impacted or bent due to the decline in coating toughness caused by the pursuit of high hardness, and loses the screen protection effect; and enhances the ability of the high-hardness DLC composite coating tempered film to ensure the hardness of the DLC coating while enhancing the adhesion between the coating and the tempered film substrate.

[0006] In one aspect, the application provides a high-hardness DLC composite coating tempered film, which comprises, from the surface of the substrate outward, a Cr / W nanometer gradient transition layer, a Si-DLC buffer layer, a W-DLC / B4C nanometer stack and an FLC fullerene-like carbon layer.

[0007] Further, the thickness of the Cr / W nanometer gradient transition layer is 50-80 nm; the thickness of the Si-DLC buffer layer is 100-150 nm; the thickness of the W-DLC sublayer in the W-DLC / B4C nanometer stack is 8-10 nm, wherein the W content is 8-10 at%, and the thickness of the B4C sublayer is 4-6 nm; and the thickness of the FLC fullerene-like carbon layer is 30-50 nm.

[0008] Further, the Si content in the Si-DLC buffer layer is 15-20 at%.

[0009] Further, the W content in the W-DLC / B4C nanometer stack is 8-10 at%.

[0010] Further, the sp of the FLC top layer is 0.1-0.2. 2 The proportion of carbon cage structure is ≥80%, and the hydrogen content is ≤5 at%.

[0011] In another aspect, the application further provides a preparation method of a high-hardness DLC composite coating tempered film, which comprises the following steps:

[0012] (1) Soak the tempered glass substrate in a 55-65℃, 4-6% NaOH solution for 9-11 min, treat it in a 35-45℃, 9-11% HF solution for 25-35 s, and then ultrasonically clean it in acetone and ethanol respectively for 9-11 min, with an ultrasonic power of 250-350 W and a frequency of 35-45 kHz, and finally ultrasonically rinse it in deionized water for 3 times to complete the cleaning;

[0013] (2) Magnetron sputter deposit a Cr / W gradient transition layer on the cleaned tempered glass substrate: control the Cr target power to linearly decrease from 200 W to 0 W, the W target power to linearly increase from 0 W to 180 W, the time to be 9-11 min, the Ar gas flow to be 35-45 sccm, and the pressure to be 0.4-0.6 Pa;

[0014] (3) Si-DLC buffer layer deposited by HiPIMS: Si target power 140-160 W, C2H2: Ar = 1:4, peak current 2 A, frequency 450-550 Hz, substrate bias -80 V;

[0015] (4) W-DLC / B4C nanolayer deposited by alternating sputtering:

[0016] Deposition of W-DLC sublayer: 150 W W target turned on, CH4 introduced to make Ar / CH4 flow ratio 20:1, deposited for 55-65 s;

[0017] Deposition of B4C sublayer: 200 W B4C target turned on, pure Ar sputtering, substrate bias -100 V, deposited for 40-50 s;

[0018] Repetition of 13-17 cycles, after deposition of 4-6 W-DLC / B4C cycles, a 1 nm thick Cr interface layer was deposited;

[0019] (5) FLC top layer deposited by PLD: pyrolytic graphite target, laser energy 250-350 mJ, frequency 9-11 Hz;

[0020] (6) Vacuum annealing: N2 atmosphere, 4x10 -3 Pa-6x10 -3 Pa, 300-400℃ for 1.5-2.5 h.

[0021] The NaOH solution can remove organic contaminants such as grease on the surface of the tempered glass substrate, and the HF solution can etch the glass surface to increase the surface roughness and improve the mechanical interlocking force between the subsequent coating and the substrate. The acetone and ethanol ultrasonic cleaning can further remove the impurities and residues on the surface, and the deionized water ultrasonic rinsing ensures the cleanliness of the substrate surface without pollution, providing a good foundation for the deposition of the subsequent coating, which is conducive to improving the adhesion between the coating and the substrate.

[0022] Vacuum annealing can eliminate residual stress in the coating and improve the microstructure of the coating. At high temperatures, atoms have higher energy and can rearrange and diffuse, reducing defects and dislocations in the coating and improving the crystallinity and density of the coating. N2 atmosphere can prevent the coating from being oxidized during annealing to ensure the performance of the coating.

[0023] Further, the Cr interface layer deposition step in step (3) comprises: turning on the Cr target, power 70-80 W, sputtering deposition in Ar atmosphere for about 2-4 seconds to form a Cr layer with a thickness of about 1 nm.

[0024] Further, Ar +Interface activation, ion energy 65-75eV, time 8-12s.

[0025] Further, the step (5) is followed by in-situ hydrophobic treatment, wherein hexamethyldisilazane vapor is introduced into the chamber at a pressure of 0.05-0.15 Pa for 4-6 min.

[0026] The hexamethyldisilazane vapor chemically reacts on the surface of the coating layer to form a layer of hydrophobic organic film. This hydrophobic film can prevent water and other contaminants from adsorbing and penetrating on the surface of the coating layer, improve the corrosion resistance and stability of the coating layer, and prolong the service life of the electronic screen protective film.

[0027] In another aspect, the application also provides the application of the high-hardness DLC composite coating strengthened film in electronic screen protection.

[0028] The application has the following advantages:

[0029] The application sets the Cr / W nanometer gradient transition layer, and there is a difference in the thermal expansion coefficient between the strengthened glass substrate and the subsequent DLC coating layer, which will generate mismatch stress when the temperature changes. The Cr / W nanometer gradient transition layer gradually changes the composition, so that the thermal expansion coefficient forms a smooth transition between the strengthened glass substrate and the DLC coating layer. This transition can effectively relieve the stress generated by the mismatch of the thermal expansion coefficient, reduce the stress concentration at the interface, thereby improving the adhesion between the coating and the substrate, and avoiding cracks or even peeling of the coating layer due to excessive stress when the coating layer is impacted or bent. In addition, the power of the Cr target and the W target is linearly adjusted to realize the gradual distribution of Cr and W elements in the transition layer, thereby forming a gradient transition of the thermal expansion coefficient. During the deposition process, Ar gas is used as the working gas and is ionized into Ar + ions under the action of the electric field, and the Ar + ions bombard the target material, so that the target atoms are sputtered and deposited on the surface of the substrate. Precise control of the flow rate and pressure of Ar gas can ensure the stability of the sputtering process and the quality of the transition layer, and ensure that the transition layer can effectively relieve the mismatch stress of the thermal expansion coefficient between the substrate and the coating layer.

[0030] This invention introduces a Si-DLC buffer layer, in which Si can form Si-C bonds with C. The presence of these chemical bonds alters the microstructure of the DLC layer, forming an effective stress buffer network. When subjected to external forces, the Si-DLC buffer layer can absorb and disperse stress through its own deformation, reducing stress transmission to other coatings and preventing damage due to stress concentration. Simultaneously, an appropriate Si content helps optimize the performance of the buffer layer, ensuring sufficient stress buffering capacity without excessively affecting the overall hardness of the coating. Furthermore, the Si-DLC buffer layer is deposited using HiPIMS (High-Power Pulsed Magnetron Sputtering) technology. HiPIMS technology has high ionization and ion energy, enabling sputtered atoms to have higher energy, thereby forming a denser and more uniform coating on the substrate surface. Precise control of parameters such as silicon target power, C2H2 to Ar flow ratio, peak current, and frequency can regulate the energy and flux of ions during deposition, affecting the composition and structure of the Si-DLC buffer layer and ensuring the formation of an effective stress buffer network. A substrate bias voltage of -80V can attract more ions to move towards the substrate surface, thereby improving the adhesion between the coating and the substrate.

[0031] This invention employs a W-DLC / B4C nanolayer structure. The addition of W improves the hardness and wear resistance of the DLC layer; however, excessive W content promotes the formation of the hard tungsten carbide phase, increasing the coating's brittleness. By precisely controlling the thickness and W content of the W-DLC sublayer, excessive brittleness can be avoided while maintaining a certain level of hardness. B4C possesses high hardness and good toughness. In the W-DLC / B4C nanolayer, the B4C sublayer enhances the coating's toughness and fatigue resistance through interfacial pinning and crack propagation inhibition. When cracks propagate within the coating, the B4C sublayer prevents further crack development, thereby improving the overall performance of the coating. Furthermore, the periodically deposited Cr interfacial layer improves the interfacial bonding between the W-DLC and B4C sublayers. It inhibits the initiation and propagation of fatigue cracks between layers, strengthens interlayer adhesion, makes the entire nanolayer structure more stable, and improves the coating's resistance to bending fatigue. Alternating sputtering deposition allows for precise control of the thickness and composition of W-DLC and B4C sublayers, forming a nanolayered structure. + Interface activation can clean and activate the interface after each layer deposition, improving the interlayer bonding. Periodic deposition of Cr interface layers can further improve interlayer interface properties, inhibit crack initiation and propagation, and enhance the stability and fatigue resistance of the nanolayered structure.

[0032] This invention incorporates an FLC-type fullerene carbon layer, which possesses unique sp... 2 The carbon cage structure imparts high hardness and good lubrication properties to the coating. A high proportion of SP... 2The carbon cage structure improves the surface hardness and wear resistance of the coating, reducing scratches. Simultaneously, the lower hydrogen content prevents the reduction of SP due to hydrogen presence. 2 The bond ratio and crosslinking degree are carefully controlled to ensure the hardness and adhesion of the film, further improving the overall performance of the coating. Furthermore, PLD (Pulsed Laser Deposition) technology is used to deposit the FLC top layer. PLD technology utilizes a high-energy pulsed laser to bombard a pyrolytic graphite target, causing target atoms and molecules to be sputtered out in plasma form and deposited on the substrate surface to form the FLC top layer. Precise control of laser energy and frequency can adjust the energy and flux of the plasma, affecting the composition and structure of the FLC top layer, ensuring the formation of a high-sp... 2 High-quality coating with carbon cage structure and low hydrogen content. Detailed Implementation

[0033] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment provides a high-hardness DLC composite coating tempered film, which includes, from the substrate surface outwards: a Cr / W nano-gradient transition layer, a Si-DLC buffer layer, a W-DLC / B4C nano-stack, and an FLC-like fullerene carbon layer.

[0036] Furthermore, the thickness of the Cr / W nanogradient transition layer is 75 nm; the thickness of the Si-DLC buffer layer is 125 nm; the thickness of the W-DLC sublayer in the W-DLC / B4C nanostack is 10 nm, wherein the W content is 9 at%, the thickness of the B4C sublayer is 5 nm; and the thickness of the FLC-like fullerene carbon layer is 40 nm.

[0037] The Si-DLC buffer layer contains 18 at% Si; the W-DLC / B4C nanolayer contains 9 at% W; and the FLC top layer contains sp 2 The carbon cage structure accounts for 80%, and the hydrogen content is 5 at%.

[0038] The method for preparing the high-hardness DLC composite coating tempered film includes the following steps: (1) The tempered glass substrate was immersed in 5% NaOH solution at 60°C for 10 min, treated with 10% HF solution at 40°C for 30 s, ultrasonically cleaned in acetone and ethanol for 10 min respectively, and ultrasonically rinsed with deionized water 3 times to complete the cleaning. The ultrasonic power was 300 W and the frequency was 40 kHz. (2) Cr / W gradient transition layer was deposited by magnetron sputtering on the cleaned tempered glass substrate: the Cr target power was linearly reduced from 200W to 0W, the W target power was linearly increased from 0W to 180W, the deposition time was 10min, the Ar gas flow rate was 40sccm, and the pressure was 0.5Pa. (3) HiPIMS deposition of Si-DLC buffer layer: silicon target power 150W, C2H2:Ar=1:4, specifically 20sccm:80sccm, peak current 2A, frequency 500Hz, substrate bias -80V; (4) Alternating sputtering deposition of W-DLC / B4C nanolayers: Deposition of W-DLC sublayer: Turn on 150W W target, introduce CH4 to make Ar / CH4 flow ratio 20:1, specifically 76sccm / 3.8sccm, and deposit for 60s; Deposition of B4C sublayer: 200W B4C target turned on, pure Ar sputtering at 40sccm, substrate bias at -100V, deposition for 45s; The process was repeated for 15 cycles. After every 5 W-DLC / B4C cycles, the Cr target was turned on at 75W, and sputtering deposition was performed for 3 seconds at 40 sccm in an Ar atmosphere to form a Cr layer with a thickness of 1 nm. After each layer deposition, Ar sputtering was performed. + Interface activation, ion energy 70eV, time 10s; (5) PLD deposition of FLC top layer: pyrolytic graphite target, laser energy of 300mJ, frequency of 10Hz, substrate temperature of -10℃, He gas pressure of 1Pa; in-situ hydrophobic treatment is carried out by introducing hexamethyldisilazane vapor into the chamber at a pressure of 0.1Pa for 5min; (6) Vacuum annealing: N2 atmosphere, 5×10 -3 The solution is obtained by heating at 5℃ / min to 350℃ and holding for 2 hours.

[0048] Example 2

[0049] This embodiment provides a high-hardness DLC composite coating tempered film, which includes, from the substrate surface outwards: a Cr / W nano-gradient transition layer, a Si-DLC buffer layer, a W-DLC / B4C nano-stack, and an FLC-like fullerene carbon layer.

[0050] Furthermore, the thickness of the Cr / W nanogradient transition layer is 50 nm; the thickness of the Si-DLC buffer layer is 100 nm; the thickness of the W-DLC sublayer in the W-DLC / B4C nanostack is 8 nm, wherein the W content is 8 at%, the thickness of the B4C sublayer is 4 nm; and the thickness of the FLC-like fullerene carbon layer is 30 nm.

[0051] The Si-DLC buffer layer contains 15 at% Si; the W-DLC / B4C nanolayer contains 8 at% W; and the FLC top layer contains sp 2 The carbon cage structure accounts for 80%, and the hydrogen content is 5 at%.

[0052] The method for preparing the high-hardness DLC composite coating tempered film includes the following steps:

[0053] (1) The tempered glass substrate was immersed in a 4% NaOH solution at 55°C for 9 min, treated with a 9% HF solution at 35°C for 25 s, ultrasonically cleaned in acetone and ethanol for 9 min respectively, and ultrasonically rinsed with deionized water 3 times to complete the cleaning. The ultrasonic power was 250W and the frequency was 35kHz.

[0054] (2) Cr / W gradient transition layer was deposited by magnetron sputtering on the cleaned tempered glass substrate: the Cr target power was linearly reduced from 200W to 0W, the W target power was linearly increased from 0W to 180W, the deposition time was 9min, the Ar gas flow rate was 35sccm, and the pressure was 0.4Pa.

[0055] (3) HiPIMS deposition of Si-DLC buffer layer: silicon target power 140W, C2H2:Ar=1:4, specifically 20sccm:80sccm, peak current 2A, frequency 450Hz, substrate bias -80V;

[0056] (4) Alternating sputtering deposition of W-DLC / B4C nanolayers:

[0057] Deposition of W-DLC sublayer: Turn on 150W W target, introduce CH4 to make Ar / CH4 flow ratio 20:1, specifically 76sccm / 3.8sccm, and deposit for 55s;

[0058] Deposition of B4C sublayer: 200W B4C target turned on, pure Ar sputtering at 40sccm, substrate bias at -100V, deposition for 40s;

[0059] The process was repeated for 15 cycles. After every 5 W-DLC / B4C cycles, the Cr target was turned on at 75W, and sputtering deposition was performed for 3 seconds at 40 sccm in an Ar atmosphere to form a Cr layer with a thickness of 1 nm. After each layer deposition, Ar sputtering was performed. +Interface activation, ion energy 70eV, time 10s;

[0060] (5) PLD deposition of FLC top layer: Pyrolytic graphite target is used, laser energy is 250mJ, frequency is 9Hz, substrate temperature is -10℃, He gas pressure is 1Pa; in-situ hydrophobic treatment is carried out, hexamethyldisilazane vapor is introduced into the chamber at a pressure of 0.05Pa for 4min;

[0061] (6) Vacuum annealing: N2 atmosphere, 4×10 -3 The solution is obtained by heating at 5℃ / min to 300℃ and holding at that temperature for 1.5 hours.

[0062] Example 3

[0063] This embodiment provides a high-hardness DLC composite coating tempered film, which includes, from the substrate surface outwards: a Cr / W nano-gradient transition layer, a Si-DLC buffer layer, a W-DLC / B4C nano-stack, and an FLC-like fullerene carbon layer.

[0064] Furthermore, the thickness of the Cr / W nanogradient transition layer is 80 nm; the thickness of the Si-DLC buffer layer is 150 nm; the thickness of the W-DLC sublayer in the W-DLC / B4C nanostack is 12 nm, wherein the W content is 10 at%, the thickness of the B4C sublayer is 6 nm; and the thickness of the FLC-like fullerene carbon layer is 50 nm.

[0065] The Si-DLC buffer layer contains 15 at% Si; the W-DLC / B4C nanolayer contains 10 at% W; and the FLC top layer contains sp 2 The carbon cage structure accounts for 80%, and the hydrogen content is 5 at%.

[0066] The method for preparing the high-hardness DLC composite coating tempered film includes the following steps: (1) The tempered glass substrate was immersed in 6% NaOH solution at 65°C for 11 min, treated with 11% HF solution at 45°C for 35 s, ultrasonically cleaned in acetone and ethanol for 11 min respectively, and ultrasonically rinsed with deionized water 3 times to complete the cleaning. The ultrasonic power was 350 W and the frequency was 45 kHz. (2) Cr / W gradient transition layer was deposited by magnetron sputtering on the cleaned tempered glass substrate: the Cr target power was linearly reduced from 200W to 0W, the W target power was linearly increased from 0W to 180W, the deposition time was 11min, the Ar gas flow rate was 45sccm, and the pressure was 0.6Pa. (3) HiPIMS deposition of Si-DLC buffer layer: silicon target power 150W, C2H2:Ar=1:4, specifically 20sccm:80sccm, peak current 2A, frequency 550Hz, substrate bias -80V; (4) Alternating sputtering deposition of W-DLC / B4C nanolayers: Deposition of W-DLC sublayer: Turn on 150W W target, introduce CH4 to make Ar / CH4 flow ratio 20:1, specifically 76sccm / 3.8sccm, and deposit for 65s; Deposition of B4C sublayer: 200W B4C target turned on, pure Ar sputtering at 40sccm, substrate bias at -100V, deposition for 50s; The process was repeated for 15 cycles. After every 5 W-DLC / B4C cycles, the Cr target was turned on at 75W, and sputtering deposition was performed for 3 seconds at 40 sccm in an Ar atmosphere to form a Cr layer with a thickness of 1 nm. After each layer deposition, Ar deposition was performed. + Interface activation, ion energy 70eV, time 10s; (5) PLD deposition of FLC top layer: pyrolytic graphite target, laser energy of 350mJ, frequency of 11Hz, substrate temperature of -10℃, He gas pressure of 1Pa; in-situ hydrophobic treatment was carried out by introducing hexamethyldisilazane vapor into the chamber at a pressure of 0.15Pa for 6min. (6) Vacuum annealing: N2 atmosphere, 5×10 -3 The solution is obtained by heating at 5℃ / min to 400℃ and holding at that temperature for 2.5 hours.

[0076] Comparative Example 1

[0077] In this comparative example, there is no Cr / W gradient layer; Si-DLC is deposited directly. The rest is the same as in Example 1, and the method is the same as in Example 1.

[0078] Comparative Example 2

[0079] In this comparative example, the B4C sublayer is removed and replaced with a pure W-DLC stack. The rest is the same as in Example 1, and the method is the same as in Example 1.

[0080] Comparative Example 3

[0081] This comparative example does not have a Cr interface layer, but everything else is the same as in Example 1, and the method is the same as in Example 1.

[0082] Comparative Example 4

[0083] In this comparative example, the Si-DLC layer has Si = 5 at%, and the rest is the same as in Example 1. The method is the same as in Example 1.

[0084] Comparative Example 5

[0085] In this comparative example, the W-DLC sublayer W = 15 at%, and the rest is the same as in Example 1, and the method is the same as in Example 1.

[0086] Comparative Example 6

[0087] In this comparative example, the hydrogen content of the FLC layer is 15 at%, and the rest is the same as in Example 1. The method is the same as in Example 1.

[0088] Experimental Example: The high-hardness DLC composite coating tempered films prepared using Examples 1-3 and Comparative Examples 1-6 were subjected to the following tests:

[0089] Scratch adhesion: According to ISO 20502:2005 "Scratch test method for fine ceramic thin films", a Rockwell C diamond indenter (radius 200μm) was used with an initial load of 1N, an end load of 50N, and a loading rate of 10N / min. The critical loads Lc1 (initial crack initiation) and Lc2 (complete peeling of film) were determined by acoustic emission signal and optical microscopy. The minimum value of three parallel tests was taken as the adhesion evaluation index.

[0090] Impact strength: Referring to the principle of GB / T 1043-1993 "Impact Test Method for Plastic Simply Supported Beams", a custom falling ball impact test was performed: the coated tempered glass was fixed to a rigid base, and a 30g quenched steel ball was used to freely fall from a height of 5cm to impact the central area. The height was increased by 5cm each time until the coating cracked. The minimum crack height of 10 samples was recorded as the impact strength test result.

[0091] Bending fatigue strength: Based on the modified ISO 178:2019 "Determination of bending properties of plastics", the coated sample (100mm×50mm) was placed in a fixture with a curvature radius of 5mm and cyclically bent 10 times at a frequency of 10Hz. After the test, the number of cracks per unit length (mm) was counted using a metallographic microscope (200×). The maximum value of 3 groups of samples was taken as the basis for evaluating bending fatigue failure.

[0092] Thermal cycling stability: According to GB / T 2423.22-2012 "Environmental testing - Part 2: Test methods - N: Temperature change", 100 cycles were performed, maintaining -40℃ for 30 min and 85℃ for 30 min. Before and after the test, the attenuation rate of the scratch critical load Lc2 was compared according to ISO 20502 method. The calculation formula is: Attenuation rate (%) = [(Lc20-Lc21) / Lc2] 0]×100%, where Lc20: initial value; Lc21: value after aging.

[0093] The results are shown in Table 1 below.

[0094] Table 1 Performance Tests

[0095]

[0096]

[0097] Based on the above data, Example 3 exhibits the highest impact strength and scratch adhesion, but its flexural fatigue crack count is slightly better than Example 1, which may be related to the stress state changes caused by the thicker buffer layer and top layer of Example 3. Example 2 has the mildest parameters and its performance is slightly lower than the other examples, but its thermal cycling decay rate is well controlled, demonstrating good overall cost-effectiveness and process stability. All three examples demonstrate excellent overall performance: high adhesion, high impact resistance, low fatigue crack count, and low thermal decay, significantly better than all comparative examples, verifying the effectiveness of the composite structure design.

[0098] Comparative Example 1: The absence of the Cr / W gradient layer significantly reduced adhesion and impact strength, while dramatically increasing the thermal cycling decay rate. This verifies the crucial role of the gradient layer in mitigating the stress caused by the mismatch in the thermal expansion coefficients of the glass / DLC. Comparative Example 2: Removing the B4C sublayer and replacing it with pure W-DLC significantly reduced impact strength, increased the number of flexural fatigue cracks, and increased the thermal cycling decay rate. This demonstrates that the B4C sublayer effectively improves toughness and fatigue resistance through the interface pinning effect and inhibiting crack propagation. Comparative Example 3: Removing the periodic Cr interface layer in the nanolayer resulted in a sharp increase in the number of flexural fatigue cracks, and a decrease in adhesion and impact strength. This indicates that the periodic Cr layer can effectively inhibit the initiation and propagation of fatigue cracks between layers, improving interlayer bonding. Comparative Example 4: Reducing the Si content in the Si-DLC layer significantly increased the thermal cycling decay rate, and also worsened adhesion and flexural fatigue resistance. This shows that sufficient Si content is crucial for forming an effective stress buffer network. In Comparative Example 5, increasing the W content in the W-DLC sublayer led to a significant decrease in impact strength, an increase in the number of bending fatigue cracks, and a higher rate of thermal decay. Excessive W content promoted the formation of the hard tungsten carbide phase, increasing brittleness.

[0099] Comparative Example 6 showed that increasing the hydrogen content in the FLC top layer weakened adhesion and slightly reduced impact strength. High hydrogen content reduced sp... 2 The bond ratio and degree of crosslinking affect the film's hardness and adhesion.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention; those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention; and all technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A high-hardness DLC composite coated tempered glass film, characterized in that, From the substrate surface outwards, the layers consist of: a Cr / W nanogradient transition layer, a Si-DLC buffer layer, a W-DLC / B4C nanolayer, and an FLC-like fullerene carbon layer.

2. The high-hardness DLC composite coated tempered film according to claim 1, characterized in that, The thickness of the Cr / W nanogradient transition layer is 50-80 nm; the thickness of the Si-DLC buffer layer is 100-150 nm; the thickness of the W-DLC sublayer in the W-DLC / B4C nanostack is 8-10 nm, wherein the W content is 8-10 at%, and the thickness of the B4C sublayer is 4-6 nm; the thickness of the FLC-like fullerene carbon layer is 30-50 nm.

3. The high-hardness DLC composite coating tempered film according to claim 1, characterized in that, The Si content in the Si-DLC buffer layer is 15-20 at%.

4. The high-hardness DLC composite coated tempered film according to claim 1, characterized in that, The W content in the W-DLC / B4C nanolayer is 8-10 at%.

5. The high-hardness DLC composite coated tempered film according to claim 1, characterized in that, The top layer of FLC sp 2 The carbon cage structure accounts for ≥80%, and the hydrogen content is ≤5 at%.

6. A method for preparing a high-hardness DLC composite coating tempered film as described in any one of claims 1-5, characterized in that the steps... include: (1) The tempered glass substrate is sequentially treated with alkaline solution, acid solution, cleaned with acetone and ethanol, and ultrasonically rinsed with water. (2) A Cr / W gradient transition layer was deposited by magnetron sputtering on the cleaned tempered glass substrate; (3) HiPIMS deposition of Si-DLC buffer layer; (4) Alternating sputtering deposition of W-DLC / B4C nanolayers: Deposit W-DLC sublayer, deposit B4C sublayer: repeat 13-17 cycles, after every 4-6 W-DLC / B4C cycles, deposit a Cr interface layer; (5) PLD deposition of FLC top layer: using pyrolytic graphite target, laser energy 250-350mJ, frequency 9-11Hz; (6) Vacuum annealing: N2 atmosphere, 4×10 -3 Pa-6×10 -3 Keep warm at 300-400℃ for 1.5-2.5 hours under Pa conditions.

7. The method for preparing a high-hardness DLC composite coating tempered film according to claim 6, characterized in that, The Cr interface layer deposition step in step (3) includes: turning on the Cr target, power 70-80W, and sputtering deposition for 2-4 seconds in an Ar atmosphere to form a Cr layer with a thickness of about 1nm.

8. The method for preparing a high-hardness DLC composite coated tempered film according to claim 4, characterized in that, In step (4), Ar is performed after each layer is deposited. + Interface activation: ion energy 65-75 eV, time 8-12 s.

9. The method for preparing a high-hardness DLC composite coating tempered film according to claim 1, characterized in that, After step (5), in-situ hydrophobic treatment is performed by introducing hexamethyldisilazane vapor into the chamber at a pressure of 0.05-0.15 Pa for 4-6 minutes.

10. The application of a high-hardness DLC composite coating tempered film as described in any one of claims 1-5 or a high-hardness DLC composite coating tempered film prepared by the preparation method described in any one of claims 6-9 in electronic screen protection.

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