DLC coated ceramic glass and coating method thereof

Abstract

The present invention relates to DLC-coated ceramic glass and a coating method thereof. Specifically, it relates to DLC-coated ceramic glass and a coating method thereof that enables mass production by forming a DLC (Diamide-Like Carbon) coating layer on ceramic glass that can easily break or be damaged using a hybrid plasma coating method applying sputtering and an ion beam source, thereby increasing the durability and lifespan of the ceramic glass.

Description

Technology Field

[0001] The present invention relates to DLC-coated ceramic glass and a coating method thereof. Specifically, it relates to DLC-coated ceramic glass and a coating method thereof that enables mass production by forming a DLC (Diamide-Like Carbon) coating layer on ceramic glass that can easily break or be damaged using a hybrid plasma coating method applying sputtering and an ion beam source, thereby increasing the durability and lifespan of the ceramic glass. Background Technology

[0002] Ceramic glass materials are widely used in high-performance fields such as electronics, optics, and aerospace due to their unique combination of mechanical strength, thermal stability, and optical transparency. However, despite these advantageous properties, their inherent brittleness and susceptibility to surface wear and degradation pose significant problems, particularly in demanding environments.

[0003] Therefore, solving these problems is important for improving the long-term performance and reliability of ceramic glass materials.

[0004] One promising alternative for improving the surface properties of ceramic glass is to apply a diamond-like carbon (DLC) coating.

[0005] DLC coatings are amorphous carbon thin films that possess both the high hardness similar to diamond and the low coefficient of friction characteristic of graphite. In particular, when applied to components, DLC coatings impart properties such as wear resistance, corrosion resistance, and lubricity. Accordingly, DLC coatings are applicable to various electronic, mechanical, automotive, aerospace, and marine components and devices, and can enhance the durability and stability of parts due to their high hardness and wear resistance.

[0006] While it is known that DLC coatings significantly improve durability and performance when applied to metal or polymer substrates, the technology for applying DLC ​​coatings to ceramic glass remains limited. The interaction between DLC coatings and ceramic glass is entirely different from that with metals or polymers. This is because the inherent properties of ceramic glass influence the adhesion, uniformity, and overall effectiveness of the DLC coating. Prior art literature

[0007] Republic of Korea Published Patent No. 10-2020-0034773: Diamond-like carbon coating by PECVD magnetron method The problem to be solved

[0008] The present invention was created to improve upon the above-mentioned problems, and aims to provide DLC-coated ceramic glass and a coating method thereof that enable mass production by forming a DLC coating layer with excellent bonding strength on ceramic glass using a hybrid plasma coating method applying sputtering and an ion beam source, thereby increasing the durability and lifespan of the ceramic glass and effectively improving its surface characteristics. means of solving the problem

[0009] The DLC-coated ceramic glass of the present invention for achieving the above objective comprises a substrate of a ceramic glass material; a multi-buffer layer formed on the surface of the substrate; and a DLC layer formed on the upper portion of the multi-buffer layer, wherein the multi-buffer layer has a multilayer structure in which a chromium layer, a chromium nitride layer formed on the upper portion of the chromium layer, and a chromium carbide layer formed on the upper portion of the chromium nitride layer are sequentially stacked.

[0010] And a method for coating DLC-coated ceramic glass to achieve the above purpose comprises: a jig preparation step of preparing a jig assembly having a plurality of mounting surfaces; a jig installation step of installing the jig assembly inside a chamber in which a sputtering target and an ion beam source are alternately arranged along the internal space; a substrate mounting step of mounting a substrate made of ceramic glass material on each of the mounting surfaces; a cleaning step of cleaning the surface of the substrate by generating a cleaning ion beam through the ion beam source while rotating the jig assembly in a certain direction; a first coating step of forming a multi-buffer layer on the surface of the substrate by the sputtering target and the ion beam source while rotating the jig assembly in a certain direction; and a second coating step of forming a DLC layer on the multi-buffer layer by generating a carbon ion beam through the ion beam source while rotating the jig assembly in a certain direction.

[0011] And the above jig assembly is assembled by stacking at least two hexagonal unit jigs, each having a plurality of mounting surfaces formed on its side.

[0012] The sputtering target is formed of a chromium material, and the first coating step comprises a) a step of forming a chromium layer on the surface of the substrate by discharging the sputtering target; b) a step of forming a chromium nitride layer on the surface of the chromium layer by generating a nitrogen ion beam through the ion beam source simultaneously with discharging the sputtering target; and c) a step of forming a chromium carbide layer on the surface of the chromium nitride layer by generating a carbon ion beam through the ion beam source simultaneously with discharging the sputtering target. Step a) is performed by discharging the sputtering target at a current of 10 to 30 A and a voltage of 300 to 400 V for 10 to 20 minutes and applying a bias voltage of -100 to -200 V to the jig assembly. Step b) is performed by discharging the sputtering target at a current of 10 to 30 A and a voltage of 300 to 400 V for 20 to 30 minutes, and The above step c) is performed by applying a bias voltage of -90 to -150V to the jig assembly and supplying nitrogen gas while applying a current of 0.5 to 1A and a voltage of 1200 to 1400V to the ion gun source, and the above step is performed by discharging the sputtering target at a current of 10 to 30A and a voltage of 300 to 400V for 10 to 20 minutes, applying a bias voltage of -90 to -150V to the jig assembly and supplying acetylene gas while applying a current of 0.5 to 1A and a voltage of 1300 to 1700V to the ion gun source. Effects of the invention

[0013] As described above, the present invention can increase the durability and lifespan of ceramic glass by effectively improving surface properties such as hardness, wear resistance, hydrophobicity, and chemical resistance through a hybrid plasma coating method applying sputtering and an ion beam source to form a DLC coating layer on ceramic glass.

[0014] In addition, the present invention can significantly increase the bonding strength of the DLC coating layer by forming a multi-layered multi-buffer layer between the ceramic glass and the DLC coating layer.

[0015] In addition, the present invention enables mass production by using a jig assembly assembled by stacking unit jigs of a polyhedral structure, thereby allowing multiple ceramic glass substrates to be DLC coated simultaneously.

[0016] The above-described invention can be usefully applied to ceramic glass, particularly to glass panels of induction cooktops. Brief explanation of the drawing

[0017] FIG. 1 is a cross-sectional view of DLC-coated ceramic glass according to an example of the present invention, and FIG. 2 is an exploded perspective view of a jig assembly applied to an example of the present invention, and FIG. 3 is a schematic diagram of a coating apparatus for forming a DLC coating layer on ceramic glass according to an example of the present invention, and FIG. 4 is a schematic diagram of the interior of a chamber applied to the coating device of FIG. 3, viewed from above. FIG. 5(a) is an FE-SEM image of the DLC layer surface, FIG. 5(b) is an FE-SEM image of the substrate cross-section, and Figure 6 is the Raman spectrum of the DLC layer surface, and Figure 7 is an XRD pattern graph of the DLC layer, and Figure 8 is a topography image of the DLC layer using an atomic force microscope (AFM), and Figure 9 shows the measurement results of the bonding strength and friction coefficient of the coating layer using a scratch tester, and Figure 10 shows the SEM image and EDX analysis results of the scratch track, and Figure 11 (a) is a graph showing the hardness values ​​of a substrate with a DLC layer formed and an uncoated substrate, and (b) is a graph showing the load-displacement curve of an indentation test of a substrate with a DLC layer formed and an uncoated substrate. Figure 12 (a) shows the contact angle experimental results of an uncoated substrate, and (b) shows the contact angle experimental results of a substrate with a DLC layer formed thereon. Figure 13 is an image showing a selected area analyzed by FE-SEM micrograph and EDX of a wear track on a DLC coated surface after tribological testing. Specific details for implementing the invention

[0018] Hereinafter, a DLC-coated ceramic glass and a coating method thereof according to a preferred embodiment of the present invention will be described in detail.

[0019] Referring to FIG. 1, a DLC-coated ceramic glass (1) according to an example of the present invention comprises a substrate (3), a multi-buffer layer (5) formed on the surface of the substrate (3), and a DLC layer (9) formed on the upper part of the multi-buffer layer (5).

[0020] The substrate (3) is formed from a ceramic glass material. In the illustrated example, the substrate (3) is formed in a plate shape, but it is obvious that it can be formed in various other shapes.

[0021] A multi-buffer layer (5) is formed on the upper surface of the substrate (3). Since the surface characteristics of the ceramic glass substrate (3) are different from those of metal or plastic materials, the characteristics of the coating layer are significantly degraded when a DLC coating layer is formed using a conventional DLC coating method.

[0022] Accordingly, the present invention forms a multi-buffer layer (5) between a substrate (3) made of ceramic glass material and a DLC layer (9). The multi-buffer layer (5) can be formed with a thickness of 1 to 10 μm. The multi-buffer layer (5) has a multilayered layer structure. For example, the multi-buffer layer (5) can be composed of a multilayer structure in which three coating layers are stacked.

[0023] As an example, the multi-buffer layer (5) is composed of a multi-layer structure in which a chromium layer (6), a chromium nitride layer (7) formed on top of the chromium layer (6), and a chromium carbide layer (8) formed on top of the chromium nitride layer (7) are sequentially stacked.

[0024] A chromium layer (6) is formed on the surface of the substrate (3). The chromium layer is composed of chromium (Cr) as its main component. The chromium layer has excellent bonding strength with the ceramic glass material, which is a heterogeneous component. Accordingly, the present invention forms the lower part of the multi-buffer layer as a chromium layer.

[0025] A chromium nitride layer (7) is formed on the chromium layer (6). The chromium nitride layer is composed of chromium nitride (CrN) as its main component. The chromium nitride layer is located between the chromium layer and the chromium carbide layer and serves to bond the chromium layer and the chromium carbide layer.

[0026] A chromium carbide layer (8) is formed on top of a chromium nitride layer (7). The chromium carbide layer is composed mainly of chromium carbide (CrC). The chromium carbide layer is located between the chromium nitride layer and the DLC layer and serves to bond the chromium nitride layer and the DLC layer.

[0027] The above-described multi-buffer layer (5) increases the bonding strength between the ceramic glass substrate (3) and the DLC layer (9), and at the same time controls the stress that may occur due to the difference in thermal expansion between the substrate (3) and the DLC layer (9).

[0028] The DLC layer (9) is formed on top of the multi-buffer layer (5). The DLC (Diamorm-Like Carbon) layer effectively improves surface properties such as hardness, wear resistance, and hydrophobicity. The DLC layer can be formed with a thickness of 1 to 10 μm.

[0029] Below, a method for coating a DLC layer on the surface of ceramic glass is described.

[0030] A coating method according to an example of the present invention comprises: a jig preparation step of preparing a jig assembly having a plurality of mounting surfaces; a jig installation step of installing the jig assembly inside a chamber in which a sputtering target and an ion beam source are alternately arranged along the periphery of an internal space; a substrate mounting step of mounting a substrate made of ceramic glass material on each mounting surface of the jig assembly; a cleaning step of cleaning the surface of the substrate by generating a cleaning ion beam through an ion beam source; a first coating step of forming a multi-buffer layer on the surface of the substrate by means of a sputtering target and an ion beam source while rotating the jig assembly in a certain direction; and a second coating step of forming a DLC layer on the surface of the multi-buffer layer by generating a carbon ion beam through an ion beam source while rotating the jig assembly in a certain direction. Each step is examined in detail.

[0031] 1. Jig preparation stage

[0032] First, prepare a jig assembly to mount a ceramic glass substrate.

[0033] The present invention utilizes a jig assembly having multiple mounting surfaces to enable mass production by simultaneously coating multiple substrates. An example of a jig assembly is illustrated in FIG. 2.

[0034] The illustrated jig assembly (10) is assembled by stacking a plurality of unit jigs (11). Each unit jig (11) is formed in a hexagonal shape and has a total of six mounting surfaces (12) on its side. A substrate is mounted on each mounting surface (12).

[0035] In addition to the hexagonal unit jig (11), various polygonal unit jigs such as squares, pentagons, and octagons can be used.

[0036] Unit jigs (11) are stacked in the vertical direction to obtain a single jig assembly (10). Two or more unit jigs are stacked. In the illustrated example, three unit jigs are shown stacked.

[0037] 2. Jig Installation Step

[0038] Next, a jig assembly (10) is installed inside the chamber (20) of the coating device.

[0039] An example of a coating device is shown in FIGS. 3 and FIGS. 4.

[0040] Referring to FIGS. 3 and 4, the coating device includes a chamber, a gas supply unit for supplying gas to the chamber, a power supply unit for supplying power, a vacuum pump for maintaining the interior of the chamber in a vacuum state, and an exhaust unit for exhausting the interior of the chamber.

[0041] The chamber (20) may be formed as an openable cylindrical structure. A rotatable table (21) is installed on the lower side of the internal space of the chamber (20), and a jig assembly (10) is installed on the table (21). The jig assembly (10) installed on the table (21) is located in the center of the internal space of the chamber (20).

[0042] In the chamber (20), sputtering targets (25) and ion beam sources (29) are alternately arranged along the internal space. In the illustrated example, two sputtering targets (25) and four ion beam sources (29) are installed. Two sputtering targets (25) are arranged to face each other, and two ion beam sources (29) are installed between the two sputtering targets (25). One sputtering target (25) and one ion beam source (29) are positioned to face each other on each mounting surface (12) of the jig assembly (10).

[0043] The sputtering target (25) can be formed from a chrome material. The sputtering target (25) is a magnetron sputtering target.

[0044] Magnetron sputtering is widely used for the formation of various thin films due to advantages such as high adhesion of the film and the ability to easily control the composition of the film compared to other PVD methods. Magnetron sputtering generates a high sputtering rate by forming a magnetic field parallel to the target surface to keep electrons around the target, thereby enhancing ionization.

[0045] However, in magnetron sputtering, it is difficult to control the microstructure of the thin film because the substrate is located outside the plasma region. To overcome this limitation, unbalanced magnetron sputtering (UBM sputtering) has recently been developed. In UBM sputtering, the magnetic field is not formed only on the target and completely confined within it; instead, a portion of the magnetic field is directed toward the substrate, allowing ionization to occur around the substrate as well. This method can increase the thin film deposition rate and improve the density and properties of the thin film.

[0046] Therefore, the present invention also utilizes a magnetron sputtering method, more preferably a non-equilibrium magnetron sputtering method. For non-equilibrium magnetron sputtering, a non-equilibrium magnetron (26) is provided on the side wall of a chamber (20) equipped with a target (25). The non-equilibrium magnetron (26) may be composed of two types of permanent magnets with different magnetic field strengths.

[0047] The ion beam source (29) is a device that generates an ion beam. The ion beam is a flow of ions that are extracted by creating a plasma state in which positive and negative charges are mixed in a neutral gas, and by creating an external environment such as a potential difference or a pressure difference therein.

[0048] An ion beam source (29) has an anode and a cathode installed at regular intervals, and gas supplied from a gas tank is injected between the anode and the cathode. An electric field is formed by the voltage applied to the anode and the cathode, and free electrons in the space between the anode and the cathode are accelerated, thereby exciting and ionizing the gas through inelastic collisions between the electrons and the neutral gas. A conventional linear ion gun can be used as the ion beam source.

[0049] Power is supplied to the ion beam source (29) and the sputtering target (25) by the power supply unit. Additionally, bias power may be applied to the jig assembly (10). Furthermore, a vacuum pump (30) is connected to the chamber (20) to maintain the inside of the chamber (20) in a constant vacuum state. By the vacuum pump (30), the inside of the chamber (20) is 1×10 -3 Up to 1×10 -8 It can be maintained at a vacuum level of torr.

[0050] And a gas supply unit is provided to supply gas to the inside of the chamber (20) or to the ion beam source (29). An argon tank (41), a nitrogen tank (42), and an acetylene tank (43) may be provided as the gas supply unit.

[0051] An exhaust section (45) for exhausting gas inside the chamber (20) is provided. Although not shown, the coating device is connected to a controller and can be controlled by the controller.

[0052] A jig assembly (10) is installed on a table (21) inside the chamber (20) of the coating device configured as above.

[0053] 3. Board mounting step

[0054] Next, a substrate (3) made of ceramic glass material is mounted on the mounting surface (12) of the jig assembly (10).

[0055] The substrate (3) can be ultrasonically cleaned using alcohol before mounting. One plate-shaped substrate (3) can be mounted on each mounting surface (12). Although not shown, a bracket or clamp for supporting the substrate (3) is installed on each mounting surface (12) to allow mounting of the substrate (3). The substrate (3) mounted on the mounting surface (12) can be spaced 10 to 20 cm apart from the sputtering target (25).

[0056] In addition, unlike the above, the substrate may be mounted on the mounting surface first before the jig assembly is inserted into the chamber.

[0057] 4. Cleaning step

[0058] Next, after sealing the chamber (20), a cleaning ion beam is generated through the ion beam source (29) to clean the surface of the substrate (3).

[0059] Operate the vacuum pump (30) to 1×10 the interior of the chamber (20). -3 Up to 1×10 -7 After maintaining a vacuum of torr, argon gas is supplied to the ion beam source (29) while rotating the jig assembly (10) 360° clockwise or counterclockwise at a speed of 3 to 7 rpm. At this time, a current of 0.5 to 1 A and a voltage of 1100 to 1300 V are applied to the ion beam source. The cleaning ion beam generated through the ion beam source, namely the argon ion beam, applies ion bombardment to the surface of the substrate to remove the thin oxide layer and impurities attached to the surface of the substrate.

[0060] The cleaning step can be performed for 40 to 80 minutes by applying a bias voltage of -60 to -100V to the jig assembly.

[0061] 5. First coating step

[0062] Next, a multi-buffer layer is formed on the surface of the cleaned substrate (3).

[0063] A multi-buffer layer can be formed on the surface of a substrate (3) using a sputtering target (25) and an ion beam source (29) while rotating the jig assembly (10) 360° clockwise or counterclockwise at a speed of 3 to 7 rpm.

[0064] Specifically, the first coating step may include a) a step of forming a chromium layer on the surface of a multi-buffer layer by discharging a sputtering target, b) a step of forming a chromium nitride layer on the surface of a chromium layer by generating a nitrogen ion beam through an ion beam source while simultaneously discharging a sputtering target, and c) a step of forming a chromium carbide layer on the surface of a chromium nitride layer by generating a carbon ion beam through an ion beam source while simultaneously discharging a sputtering target.

[0065] In step a) above, a current of 10 to 30 A and a voltage of 300 to 400 V are applied to the sputtering target to discharge it for 10 to 20 minutes. At this time, a bias voltage of -100 to -200 V is applied to the jig assembly. Additionally, while discharging the sputtering target, argon gas can be supplied to the ion beam source to generate an argon ion beam. In this case, a current of 0.5 to 1 A and a voltage of 1100 to 1300 V are applied to the ion beam source. Through step a), a chromium layer is formed on the surface of the substrate.

[0066] In step b) above, a current of 10 to 30 A and a voltage of 300 to 400 V are applied to the sputtering target to discharge it for 20 to 30 minutes. At this time, a bias voltage of -90 to -150 V is applied to the jig assembly. Simultaneously with discharging the sputtering target, nitrogen gas is supplied to the ion beam source to generate a nitrogen ion beam. A current of 0.5 to 1 A and a voltage of 1200 to 1400 V are applied to the ion beam source. Through step b), a chromium nitride layer is formed on the surface of the chromium layer.

[0067] Step c) above involves applying a current of 10 to 30 A and a voltage of 300 to 400 V to a sputtering target and discharging it for 10 to 20 minutes. At this time, a bias voltage of -90 to -150 V is applied to the jig assembly. Simultaneously with discharging the sputtering target, acetylene gas is supplied to an ion beam source to generate a carbon ion beam. A current of 0.5 to 1 A and a voltage of 1300 to 1700 V are applied to the ion beam source. Through step c), a chromium carbide layer is formed on the surface of the chromium nitride layer.

[0068] Through the first coating step described above, a multi-buffer layer can be formed between the substrate and the DLC layer, wherein a chromium layer, a chromium nitride layer formed on top of the chromium layer, and a chromium carbide layer formed on top of the chromium nitride layer are sequentially stacked.

[0069] 6. Second coating step

[0070] Next, a DLC layer is formed on the surface of the multi-buffer layer.

[0071] A carbon ion beam is generated by supplying acetylene gas to an ion beam source while rotating the jig assembly (10) 360° clockwise or counterclockwise at a speed of 3 rpm, applying a current of 0.5 to 1 A and a voltage of 1300 to 1700 V to the ion beam source.

[0072] The second coating step can be performed for 50 to 100 minutes by applying a bias voltage of -100 to -200V to the jig assembly. Through the second coating step, a DLC layer with excellent surface properties such as hardness, wear resistance, and hydrophobicity can be formed.

[0073] Hereinafter, examples are presented to aid in understanding the present invention; however, the following examples are merely illustrative of the present invention and the scope of the present invention is not limited to the following examples.

[0074] (Example)

[0075] A coating experiment was performed on the surface of a ceramic glass substrate mounted on a jig assembly using the coating device shown in FIGS. 3 and 4. During the cleaning and first coating process, the jig assembly was rotated 360° counterclockwise at a speed of 5 rpm, and during the second coating process, the jig assembly was rotated 360° counterclockwise at a speed of 3 rpm.

[0076] After sealing the chamber, the inside of the chamber is 5×10 -5 After maintaining a vacuum of torr, argon gas was supplied to the ion beam source, and a current of 0.8A and a voltage of 1200V were applied. Then, a bias voltage of -80V was applied to the jig assembly, and the substrate was cleaned for 60 minutes.

[0077] Then, a bias voltage of -150V was applied to the jig assembly, and argon gas was supplied to the ion beam source while applying a current of 0.8A and a voltage of 1200V. At the same time, a current of 20A and a voltage of 360V were applied to the sputtering target and discharged for 14 minutes to form a chromium layer on the surface of the substrate.

[0078] Then, a bias voltage of -120V was applied to the jig assembly, and nitrogen gas was supplied to the ion beam source while applying a current of 0.8A and a voltage of 1300V. At the same time, a current of 20A and a voltage of 360V were applied to the sputtering target and discharged for 28 minutes to form a chromium nitride layer on the surface of the chromium layer.

[0079] Then, a bias voltage of -120V was applied to the jig assembly, and acetylene gas was supplied to the ion beam source while applying a current of 0.8A and a voltage of 1500V. At the same time, a current of 20A and a voltage of 360V were applied to the sputtering target and discharged for 14 minutes to form a chromium carbide layer on the surface of the chromium nitride layer.

[0080] Then, a bias voltage of -150V was applied to the jig assembly, and acetylene gas was supplied while applying a current of 0.8A and a voltage of 1500V to the ion beam source to form a DLC layer on the surface of the chromium carbide layer for 75 minutes.

[0081] Surface Characteristics Analysis Experiment

[0082] - Experimental method

[0083] The surface and cross-section were observed using a field-effect scanning electron microscope (FE-SEM) (Hitachi, S-4700, Japan). The chemical composition of the coating layer was analyzed using an X-ray spectrometer (EDX) (Hitachi, EX-200, Japan) in conjunction with INCA quantitative analysis software. The phase structure was investigated using X-ray diffraction (XRD) (X' Pert PRD, PANalytical, Netherlands).

[0084] The hardness of the coating layer was measured using a nanoindentation tester (HM2000, Fischer, Germany). The wear characteristics of the coating layer were evaluated at room temperature using a pin-on-disk wear tester (CSM, THT), and the bond strength of the coating layer was evaluated by creating scratches with a diamond tip while applying a constant load of 0 to 30 N using a scratch tester (JSLT022). Surface energy was measured using a contact angle protractor (KSA100, Kruss, Germany).

[0085] -Experimental results

[0086] Figure 5(a) shows an FE-SEM image of the DLC layer surface, and Figure 5(b) shows an FE-SEM image of the substrate cross-section.

[0087] Referring to Figure 5(a), the surface was found to have a relatively uniform texture with fine particle characteristics. The uniformity of the surface exhibits consistent coating characteristics without defects such as cracks or voids, which is an important factor in the protective performance of the DLC layer.

[0088] And referring to 5(b), it was found that a three-layer multi-buffer layer was formed between the bottom substrate and the top DLC layer.

[0089] Figure 6 shows the Raman spectrum of the DLC layer surface.

[0090] Referring to Fig. 6, the illustrated Raman spectrum shows two characteristic bands, which exhibit typical characteristics of the DLC coating. G peak (approx. 1580 cm⁻¹) -1 ) is generally associated with a graphite (sp2) carbon structure and indicates the presence of sp2 bonded carbon atoms arranged in a graphite structure. And the D peak (approx. 1350 cm⁻¹) -1 ) is associated with the disorder of the carbon structure and is often linked to sp2 hybridized carbon atoms in disordered or defect-heavy states. The relative intensity and shape of these peaks provide information about the degree of disorder and the sp² / sp³ ratio of the DLC coating. A G peak higher than the D peak suggests a higher graphite content and may indicate the presence of a mixture of amorphous carbon phases.

[0091] Figure 7 shows the XRD pattern graph of the DLC layer.

[0092] Referring to FIG. 7, the diffraction peaks observed in the 2θ range of 10° to 80° indicate the presence of various crystal phases. The prominent peak (002) at approximately 13.83° is attributed to graphite, indicating the presence of a graphitic carbon structure within the DLC layer. The peak (111) at 35.51° is chromium nitride (CrN), suggesting the formation of a CrN phase between the DLC layer and the substrate. The peak at 42.71° corresponds to carbon, and the peak at 52.71° indicates a multiphase carbon structure. The peaks at 56.07° and 63.46° are attributed to chromium (Cr) and chromium carbide (CrC), respectively.

[0093] Figure 8 shows topography images of the DLC layer using an atomic force microscope (AFM).

[0094] Referring to Fig. 8, the Ra value of the DLC layer surface was found to be 5.486 nm, confirming that it has a smooth surface.

[0095] Figure 9 shows the measurement results of the bonding strength and friction coefficient of the coating layer using a scratch tester.

[0096] Referring to Fig. 9, it was found that the bonding strength of the DLC layer was excellent, as no significant delamination occurred even when the load was increased up to 30N. Also, the coefficient of friction was found to be low at approximately 0.1.

[0097] Figure 10 shows the SEM image and EDX analysis results of the scratch track. In Figure 10, (a) is the surface of an uncoated substrate, and (b) is the DLC-coated surface.

[0098] Referring to Fig. 10, the SEM image showed that the surface of the uncoated substrate (Fig. 6a) was severely damaged due to significant wear and surface deformation. On the other hand, the surface of the DLC layer (Fig. 6b) showed only minor microcracks with no evidence of surface delamination.

[0099] Elemental analysis results support these observations. As can be seen in Fig. 6a-1, the surface of the uncoated substrate is composed mainly of oxygen, silicon, and aluminum, whereas carbon peaks were detected in the DLC layer as shown in Fig. 6b-1. This indicates that a DLC coating composed mainly of carbon was successfully formed. Due to the presence of a high concentration of carbon, the integrity and bonding strength of the DLC layer can be confirmed even after a scratch test.

[0100] Figure 11 (a) is a graph showing the hardness values ​​of a substrate with a DLC layer and an uncoated substrate, and (b) is a graph showing the load-displacement curve of an indentation test of a substrate with a DLC layer and an uncoated substrate. In Figure 11, blue represents the individual measured values ​​of the substrates with the DLC layer, and red represents the average value. Gray represents the individual measured values ​​of the uncoated substrates, and black represents the average value.

[0101] Referring to Fig. 11, the indentation hardness of the substrate with the DLC layer formed was found to be approximately 22 GPa, while the hardness of the uncoated substrate was 7.8 GPa. It was confirmed that the substrate with the DLC layer possesses excellent hardness due to its carbon content and dense structure. This clearly demonstrates that the DLC layer significantly improves the hardness and mechanical properties of the ceramic glass substrate.

[0102] Furthermore, substrates with a DLC layer were found to exhibit greater resistance under load compared to uncoated substrates, showing significantly smaller deformation. This implies that substrates with a DLC layer are more suitable for applications requiring high wear resistance and mechanical durability.

[0103] Figure 12 (a) shows the contact angle test results of an uncoated substrate, and (b) shows the contact angle test results of a substrate with a DLC layer formed thereon.

[0104] Referring to Fig. 12, the contact angle of the substrate surface coated with DLC was found to be much higher than that of the uncoated substrate surface. Therefore, it can be seen that the DLC coating can effectively increase the hydrophobicity of ceramic glass. This is consistent with the known properties of DLC coatings that impart hydrophobic characteristics.

[0105] Figure 13 shows a high-magnification inset (spectrum A and spectrum B) showing a selected area analyzed by EDX and an FE-SEM micrograph of a wear track on a DLC coated surface after tribological testing.

[0106] Referring to Figure 13, the DLC coating was found to maintain its properties even under tribological stress. Spectrum A confirmed that it is a region primarily rich in carbon, as expected, while Spectrum B shows an increase in chromium and oxygen due to material migration or minor oxidation during testing.

[0107] These results demonstrate the excellent wear resistance of the DLC coating and confirm that the wear rate is extremely low. The fact that the typical DLC surface structure is maintained despite wear tests suggests that the protective properties of the coating layer can be preserved even under demanding conditions.

[0108] The present invention has been described above with reference to embodiments, but this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent embodiments are possible therefrom. Accordingly, the true scope of protection of the present invention should be determined only by the appended claims. Explanation of the symbols

[0109] 1: DLC-coated ceramic glass 3: Substrate 5: Multi-buffer layer 6: Chrome layer 7: Chromium nitride layer 8: Chromium carbide layer 9: DLC Layer 10: Jig Assembly 11: Unit jig 12: Mounting surface 20: Chamber 25: Sputtering target 29: Ion beam source

Claims

Claim 1 A DLC-coated ceramic glass comprising: a substrate made of ceramic glass material; a multi-buffer layer formed on the surface of the substrate; and a DLC layer formed on the upper portion of the multi-buffer layer; wherein the multi-buffer layer has a multi-layer structure in which a chromium layer, a chromium nitride layer formed on the upper portion of the chromium layer, and a chromium carbide layer formed on the upper portion of the chromium nitride layer are sequentially stacked. Claim 2 A method for DLC coating of ceramic glass, characterized by comprising: a jig preparation step of preparing a jig assembly having a plurality of mounting surfaces; a jig installation step of installing the jig assembly inside a chamber in which a sputtering target and an ion beam source are alternately arranged along the periphery of an internal space; a substrate mounting step of mounting a substrate made of ceramic glass material on each of the mounting surfaces; a cleaning step of cleaning the surface of the substrate by generating a cleaning ion beam through the ion beam source while rotating the jig assembly in a certain direction; a first coating step of forming a multi-buffer layer on the surface of the substrate by the sputtering target and the ion beam source while rotating the jig assembly in a certain direction; and a second coating step of forming a DLC layer on the surface of the multi-buffer layer by generating a carbon ion beam through the ion beam source while rotating the jig assembly in a certain direction. Claim 3 A method for DLC coating of ceramic glass according to claim 2, wherein the jig assembly is assembled by stacking at least two hexagonal unit jigs, each having a plurality of mounting surfaces formed on its side. Claim 4 In claim 2, the sputtering target is formed of a chromium material, and the first coating step comprises a) a step of forming a chromium layer on the surface of the substrate by discharging the sputtering target; b) a step of forming a chromium nitride layer on the surface of the chromium layer by generating a nitrogen ion beam through the ion beam source simultaneously with discharging the sputtering target; and c) a step of forming a chromium carbide layer on the surface of the chromium nitride layer by generating a carbon ion beam through the ion beam source simultaneously with discharging the sputtering target. Step a) is performed by discharging the sputtering target at a current of 10 to 30 A and a voltage of 300 to 400 V for 10 to 20 minutes and applying a bias voltage of -100 to -200 V to the jig assembly. Step b) is performed by discharging the sputtering target at a current of 10 to 30 A and a voltage of 300 to 400 V for 20 to 30 minutes. A method for DLC coating of ceramic glass, characterized by discharging, applying a bias voltage of -90 to -150V to the jig assembly, and supplying nitrogen gas while applying a current of 0.5 to 1A and a voltage of 1200 to 1400V to the ion gun source, wherein step c) is performed by discharging the sputtering target at a current of 10 to 30A and a voltage of 300 to 400V for 10 to 20 minutes, applying a bias voltage of -90 to -150V to the jig assembly, and supplying acetylene gas while applying a current of 0.5 to 1A and a voltage of 1300 to 1700V to the ion gun source.

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