Novel coating type ring for optical lens processing and preparation method thereof
By depositing a graphene film on the surface of the optical lens mold ring, the problem of the ring being easily damaged under high temperature and high pressure was solved, the wear resistance and demolding performance of the ring were improved, the service life of the mold was extended, and the forming quality of small-sized lenses was improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING GRAPHENE INST
- Filing Date
- 2026-01-28
- Publication Date
- 2026-05-19
AI Technical Summary
Existing optical lens mold rings are prone to problems such as detachment, oxidation, and wear under high temperature and high pressure, resulting in limited mold life. Demolding is particularly difficult in the processing of small-sized lenses, and traditional coating methods result in uneven coating and poor adhesion on complex structures.
Graphene films are deposited on the surface of the ring. Continuous and dense graphene films are grown on the inner wall and contact surface of the ring using chemical vapor deposition (CVD) to form a high-strength alloy matrix-graphene self-lubricating surface structure, which improves the wear resistance and demolding performance of the ring.
It significantly improves the high temperature resistance, wear resistance and lubrication performance of the molding ring, reduces demolding adhesion, extends the service life of the mold, and improves the forming quality of small-sized lenses.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of optical lens technology, specifically relating to a novel coated ring for optical lens processing and its preparation method. Background Technology
[0002] Optical lens molding technology, especially the molding of glass aspherical lenses, places extremely high demands on the mold's high-temperature resistance, thermal conductivity, wear resistance, demolding performance, and lifespan. The mold typically consists of an upper mold, a lower mold, and a mold ring, which presses and shapes the glass preform under high temperature and pressure. The mold ring, as the sidewall structure of the molding cavity, is in direct contact with the molten glass and withstands thermal cycling, mechanical stress, and chemical corrosion; its performance directly affects the lens forming quality and the overall lifespan of the mold.
[0003] Currently, mold materials mostly utilize high-hardness, high-melting-point materials such as tungsten carbide (hard alloy), metallic tungsten, and stainless steel. To cope with the harsh conditions of high temperature, high pressure, and glass adhesion, surface strengthening of key mold components—especially the mold ring that directly forms the cavity—is a common technical approach. For example, Chinese patent CN104843972B (A novel mold core for optical lens processing and its preparation method) explicitly proposes the technical concept of "surface treatment of tungsten mold cores to improve surface quality and enhance demolding performance." Specific methods include forming a tungsten carbide layer, a SiN layer, or a diamond coating on the mold core surface. This approach aims to utilize the hardness, heat resistance, and low surface energy of the coating to improve wear resistance and demolding effect. Surface coating treatments (such as tungsten carbide, diamond films, SiN films, etc.) are then applied to enhance wear resistance and demolding performance. However, existing coatings may still experience problems such as peeling, oxidation, and wear under extreme high temperatures (>500℃) and long-term thermal cycling, resulting in limited mold life and high maintenance costs.
[0004] When the lens diameter is large, traditional processing methods typically employ a combination of upper and lower molding followed by edge grinding. However, as the lens diameter decreases (especially to <10 mm), edge grinding becomes difficult due to the small workpiece size, and is prone to breakage or decreased precision. Therefore, small-sized lenses often utilize a full molding process without edge grinding, directly forming the final shape with the aid of auxiliary structures such as molding rings, thus avoiding the difficulties associated with subsequent finishing. However, in actual production, due to the difference in thermal expansion coefficients between the glass and the molding ring materials, the shrinkage of the glass after cooling is generally greater than that of the molding ring. When the lens diameter is greater than 4 mm, a suitable gap is formed between the two, facilitating lens removal; but when the lens diameter is less than or equal to 4 mm, the gap is too small, easily causing the lens to jam or become difficult to remove during demolding.
[0005] For small molds with deep holes, narrow slits, or complex three-dimensional structures (such as the inner wall of a mold ring), physical vapor deposition methods can result in uneven coating and poor adhesion. Therefore, developing a mold ring that can overcome these defects and possess high temperature resistance, wear resistance, and the ability to alleviate demolding adhesion is of significant practical importance. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention proposes a solution for depositing a graphene film on the surface of a mold ring. Graphene possesses excellent thermal conductivity, high mechanical strength, good chemical inertness, and self-lubricating properties. This coating can significantly improve the high-temperature resistance, wear resistance, and surface lubrication performance of the mold ring, thereby alleviating demolding adhesion, reducing removal resistance, and effectively extending the mold's service life while improving the forming quality of small-sized lenses. Based on this, this invention also proposes a chemical vapor deposition (CVD) method for directly growing graphene on the mold ring. A hydrogen-poor process enables growth, depositing a uniform graphene film on the inner wall of the mold ring and the contact surfaces with the upper and lower molds. This improves the mold's demolding performance and heat dissipation, thereby extending the mold ring's lifespan.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] In a first aspect, the present invention provides a coated ring for optical lens processing.
[0009] The coated ring for optical lens processing provided by the present invention includes a tungsten carbide ring and a graphene film deposited on the surface of the tungsten carbide ring.
[0010] Furthermore, the graphene film is prepared by chemical vapor deposition.
[0011] Furthermore, the surface of the mold ring includes the precision-molded inner wall surface of the mold ring and the contact surface with the upper mold (upper mold core) and the lower mold (lower mold core).
[0012] In a second aspect, the present invention provides a method for preparing the coated ring for optical lens processing as described in the first aspect.
[0013] The preparation method provided by this invention includes the following steps: 1) Pretreatment: Clean the tungsten carbide ring to ensure that the surface of the ring is clean; 2) Placement of the tungsten carbide ring: Place the tungsten carbide ring vertically in the carrier; 3) CVD growth of graphene: The carrier containing the shaped ring is placed in the constant temperature zone of the CVD furnace, ensuring that the gas inlet direction of the CVD furnace is parallel to the axis of the tungsten carbide shaped ring; in an atmosphere containing carbon source and hydrogen, graphene is grown on the surface of the shaped ring by chemical vapor deposition; wherein, during the chemical vapor deposition process, the ambient temperature is raised to the growth temperature of graphene before the carbon source is introduced, and no reducing gas is introduced during the heating process; in the atmosphere containing carbon source and hydrogen, the carbon-hydrogen ratio (flow rate ratio) of carbon source and hydrogen is: 1:1 ≥ carbon-hydrogen ratio ≥ 1:3.
[0014] In step 1) of the above method, the cleaning agent used for cleaning can be ethanol, and the cleaning method can be ultrasonic cleaning.
[0015] In step 2) of the above method, multiple rings can be placed in the carrier, which can realize the simultaneous growth of multiple rings and help to achieve mass production.
[0016] In step 3) of the above method, the axial direction of the shaped ring refers to the direction along the central axis of symmetry of the shaped ring, which is consistent with the direction of the molding movement.
[0017] In step 3) of the above method, the carbon source is selected from at least one of the following: methane, propane, acetylene, ethylene or ethanol.
[0018] In one specific embodiment of the present invention, the carbon source is methane, the reducing gas is hydrogen, and the flow ratio of methane to hydrogen is 45:100.
[0019] In step 3) of the above method, during the chemical vapor deposition process, the input flow rate of the carbon source is 30-100 sccm, and the input flow rate of the reducing gas is 20-200 sccm.
[0020] In one specific embodiment of the present invention, the input flow rate of the carbon source is 40 sccm, and the input flow rate of the reducing gas is 80 sccm.
[0021] In step 3) of the above method, a carrier gas is also introduced during the chemical vapor deposition process. The carrier gas can be selected from at least one of the following: argon or nitrogen. The input flow rate of the carrier gas can be 100–1000 sccm.
[0022] In one specific embodiment of the present invention, the input flow rate of the carrier gas is 800 sccm.
[0023] In step 3) of the above method, the growth temperature of graphene during the chemical vapor deposition process is 800-1080℃ and the growth time is 200-500 min.
[0024] In step 3) of the above method, the heating rate of raising the ambient temperature to the growth temperature of graphene before inputting the carbon source can be 5-10℃ / min.
[0025] In step 3) of the above method, during the chemical vapor deposition process, after the ambient temperature is raised to the graphene growth temperature, the growth temperature is maintained for 5 to 30 minutes (e.g., 30 minutes) before the carbon source is introduced.
[0026] Thirdly, the present invention provides an optical lens molding die.
[0027] The optical lens molding die provided by the present invention includes a coated ring as described in the first aspect of the present invention or a coated ring prepared by the method described in the second aspect of the present invention.
[0028] The coating ring provided by this invention is not limited to optical lens molding scenarios, but is also suitable for scenarios with high requirements for demolding performance, wear resistance and thermal conductivity in room temperature and high temperature environments.
[0029] This invention involves in-situ growth of continuous, dense multilayer graphene films on the precision-formed inner wall surface and the contact surfaces with the upper and lower molds of a tungsten carbide ring in a traditional optical lens molding die using chemical vapor deposition. This results in a composite ring structure of "high-strength alloy substrate - graphene self-lubricating surface." This structure aims to simultaneously improve the ring's thermal conductivity, oxidation resistance, and demolding performance.
[0030] Although the growth temperature of CVD graphene (typically 800-1080°C) is lower than the sintering temperature, it is still within the high-temperature range. If a reducing gas is introduced during the heating process, the introduced hydrogen will undergo a reversible decarburization reaction with the tungsten carbide (WC) on the surface of the tungsten steel: WC + 2H₂ W + CH4. This leads to the decomposition of surface WC, the removal of carbon, and the formation of brittle free tungsten or cobalt-tungsten brittle phases, resulting in a decarburized layer several micrometers thick on the surface. This layer exhibits a sharp decrease in hardness, wear resistance, and strength, becoming porous and brittle, thus becoming a crack initiation point and severely impairing the surface properties and service life of tungsten steel. Therefore, employing a hydrogen-deficient process can effectively avoid this decarburization reaction and improve the service life of tungsten steel rings. Attached Figure Description
[0031] Figure 1 The image shows the Raman spectrum of the graphene film grown on the surface of the tungsten carbide ring in Example 1. Figure 2 An optical microscope image of the surface of the coated ring prepared in Example 1; Figure 3 White light interference comparison of surface morphology and roughness of the original ring and the graphene-coated ring prepared in Example 1: (a) Original ring; (b) Graphene-coated ring prepared in Example 1; Figure 4 Optical micrographs of the graphene film deposited on the inner wall of the ring when the ring axis is perpendicular to the airflow direction in Comparative Example 1: (a) upper inner wall surface; (b) lower inner wall surface; Figure 5 The image shows the microstructure of the graphene film deposited on the surface of the ring under conditions of insufficient reducing gas in Comparative Example 2. Figure 6 An optical microscope image of the surface of the coated ring prepared in Comparative Example 2; Figure 7 The surface mechanical properties of the ring under different conditions. Detailed Implementation
[0032] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.
[0033] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.
[0034] In this embodiment, a tubular CVD system is used for graphene growth. The core reaction chamber is a horizontally placed quartz tube with a diameter of 150 mm and a length of 2000 mm. This size design ensures sufficient isothermal zone length and a stable gas flow field, providing a reliable equipment foundation for the preparation of uniform, high-quality graphene films with ring surfaces. When using reaction tubes of other sizes, the gas flow rate and carrier loading described in this embodiment can be adjusted proportionally according to their cross-sectional area and isothermal zone volume to maintain a similar reaction atmosphere and mass transfer conditions.
[0035] Example 1 (The annular axis is parallel to the gas flow direction, hydrogen-poor) 1. Pretreatment: The tungsten carbide ring is ultrasonically cleaned with ethanol to ensure that the surface of the ring is absolutely clean.
[0036] 2. Placement of the tungsten carbide shaped ring: Place the tungsten carbide shaped ring vertically in the glass plate carrier, with the plane of the glass plate carrier parallel to the airflow direction, that is, the axial direction of the shaped ring is parallel to the airflow direction.
[0037] 3. CVD growth: 3.1 Place the carrier containing the molding ring in the constant temperature zone of the CVD furnace, ensuring that the gas inlet direction of the CVD furnace is parallel to the axis of the molding ring.
[0038] 3.2 Evacuate the chamber to a vacuum state to remove all air from the CVD furnace.
[0039] 3.3 Fill the cavity with argon gas to atmospheric pressure.
[0040] 3.4 Heat up from room temperature to the target temperature of 1020℃ in 100 minutes, and introduce 800 sccm Ar.
[0041] 3.5 Incubate at the growth temperature for 30 minutes after reaching the growth temperature.
[0042] 3.6 Growth: Methane was used as the carbon source, and hydrogen was used as the reducing gas. The growth time was 300 min. Ar:H2:CH4 = 800 sccm:100 sccm:45 sccm.
[0043] 3.7 Cool down by shutting off the carbon source and hydrogen gas, and then cool to room temperature under an argon protective atmosphere.
[0044] The graphene film prepared in Example 1 was characterized. The Raman spectrum of this graphene is shown below. Figure 1 As shown. By Figure 1 It can be seen that the spectrum is at approximately 1580 cm⁻¹ - A distinct G peak appears at approximately 2700 cm⁻¹. - A distinct 2D peak appears at position ¹, and the 2D peak has a wide full width at half maximum (FWHM) and a symmetrical shape, indicating that the deposited film is a multilayer graphene structure; simultaneously, at approximately 1350 cm⁻¹... - No significant D peak was observed at ¹, indicating that the prepared graphene film has few defects and good crystallization quality.
[0045] The coated ring prepared in Example 1 was characterized. An optical microscope image of the ring is shown below. Figure 2 As shown. By Figure 2 It can be seen that a graphene film layer with uniform wall thickness is formed by deposition on the surface of the tungsten carbide ring.
[0046] White light interferometry was used to characterize the original ring (tungsten carbide ring) and the coated ring prepared in Example 1. Their white light interferograms are shown below. Figure 3 As shown. Figure 3 The surface roughness Ra of the original ring in (a) is 120 nm. Figure 3 In Example (b), the surface roughness Ra of the ring after being coated with a graphene film is 42 nm.
[0047] The service life of the original ring (tungsten carbide ring) and the coated ring prepared in Example 1 were tested. The results are shown in Table 1.
[0048] Table 1. Comparison of molding life test results between the original tungsten carbide ring and the graphene-coated ring prepared in Example 1.
[0049] As shown in Table 1, the coated ring prepared using the method of this invention has significantly better service life and demolding performance than the untreated original ring. The original ring developed indentations and became difficult to remove after 1000 molding cycles, and was scrapped after 3000 molding cycles. In contrast, the graphene-coated ring of this invention maintained its initial usability after 3000 molding cycles. Although indentations appeared on the inner wall after 4000-5000 molding cycles, removal and removal remained smooth, allowing it to continue to be used. This indicates that the graphene coating effectively improves the wear resistance and anti-adhesion properties of the ring, significantly extending the mold life.
[0050] Example 2 (The annular axis is parallel to the airflow direction, hydrogen-poor) This embodiment is basically the same as Embodiment 1, except that Ar:H2:CH4 = 800sccm:135sccm:45sccm in 3.6 of Embodiment 1 is adjusted.
[0051] The coated ring prepared by the method of this embodiment has similar performance to the coated ring prepared in Example 1.
[0052] Example 3 (The annular axis is parallel to the gas flow direction, hydrogen-poor) This embodiment is basically the same as Embodiment 1, except that Ar:H2:CH4 = 800sccm:90sccm:45sccm in 3.6 of Embodiment 1 is adjusted.
[0053] The coated ring prepared by the method of this embodiment has similar performance to the coated ring prepared in Example 1.
[0054] Example 4 (The annular axis is parallel to the gas flow direction, hydrogen-poor) This embodiment is basically the same as Embodiment 1, except that Ar:H2:CH4 = 800sccm:45sccm:45sccm is adjusted in 3.6 of Embodiment 1.
[0055] The coated ring prepared by the method of this embodiment has similar performance to the coated ring prepared in Example 1.
[0056] Example 5 (The annular axis is parallel to the gas flow direction, hydrogen-poor) This embodiment is basically the same as Embodiment 1, except that the growth temperature in 3.2 of Embodiment 1 is adjusted to 900℃ and the carbon source in 3.6 is acetylene.
[0057] The coated ring prepared by the method of this embodiment has similar performance to the coated ring prepared in Example 1.
[0058] Example 6 (The annular axis is parallel to the gas flow direction, hydrogen-poor) This embodiment is basically the same as Embodiment 1, except that the growth temperature in 3.4 of Embodiment 1 is adjusted to 950°C and the carbon source in 3.6 is ethylene.
[0059] The coated ring prepared by the method of this embodiment has similar performance to the coated ring prepared in Example 1.
[0060] Comparative Example 1 (The annular axis is perpendicular to the gas flow direction, hydrogen-poor) 1. Pretreatment: The molding ring is ultrasonically cleaned with ethanol to ensure that the surface of the molding ring is absolutely clean.
[0061] 2. Placement of the tungsten carbide shaped ring: Place the tungsten carbide shaped ring flat on the glass plate carrier, with the plane of the glass plate carrier parallel to the airflow direction, that is, the axial direction of the shaped ring is perpendicular to the airflow direction.
[0062] 3. CVD growth: 3.1 Place the carrier containing the molding ring in the constant temperature zone of the CVD furnace, ensuring that the gas inlet direction of the CVD furnace is perpendicular to the axis of the molding ring.
[0063] 3.2 Evacuate the chamber to a vacuum state to remove all air from the CVD furnace.
[0064] 3.3 Fill the cavity with argon gas to atmospheric pressure.
[0065] 3.4 Heat up from room temperature to the target temperature of 1020℃ in 100 minutes, and introduce 800 sccm Ar.
[0066] 3.5 Incubate at the growth temperature for 30 minutes after reaching the growth temperature.
[0067] 3.6 Growth: Methane was used as the carbon source, and hydrogen was used as the reducing gas. The growth time was 300 min, and the ratio of Ar:H2:CH4 was 800 sccm:100 sccm:45 sccm.
[0068] 3.7 Cool down by shutting off the carbon source and hydrogen gas, and then cool to room temperature under an argon protective atmosphere.
[0069] The graphene film with the inner wall of the ring prepared in Comparative Example 1 was characterized, and its optical micrograph is shown below. Figure 4 As shown. By Figure 4 It can be seen that when the ring axis is perpendicular to the airflow direction, the deposited graphene film exhibits obvious layering, resulting in uneven film thickness and continuity. Specifically, the inner wall surface of the upper ring ( Figure 4 a) The graphene thickness is significantly greater than that on the downward-facing inner wall surface ( Figure 4 (b) This is because, under horizontal airflow conditions, the carbon source distribution on the upper surface is more concentrated, while the carbon source supply on the lower surface is relatively insufficient, resulting in uneven graphene growth and the inability to form a continuous and dense protective layer.
[0070] Comparative Example 2 (the annular axis is parallel to the airflow direction, and the carbon-to-hydrogen ratio is too high): 1. Pretreatment: The molding ring is ultrasonically cleaned with ethanol to ensure that the surface of the molding ring is absolutely clean.
[0071] 2. Placement of the tungsten carbide shaped ring: Place the tungsten carbide shaped ring vertically in the glass plate carrier, with the plane of the glass plate carrier parallel to the airflow direction, that is, the axial direction of the shaped ring is parallel to the airflow direction.
[0072] 3. CVD growth: 3.1 Place the carrier containing the molding ring in the constant temperature zone of the CVD furnace, ensuring that the gas inlet direction of the CVD furnace is parallel to the axis of the molding ring.
[0073] 3.2 Evacuate the chamber to a vacuum state to remove all air from the CVD furnace.
[0074] 3.3 Fill the cavity with argon gas to atmospheric pressure.
[0075] 3.4 Heat up from room temperature to the target temperature of 1020℃ in 100 minutes, and introduce 800 sccm Ar.
[0076] 3.5 Incubate at the growth temperature for 30 minutes after reaching the growth temperature.
[0077] 3.6 Growth: Methane was used as the carbon source; no reducing gas was introduced; the growth time was 300 min. Ar:H2:CH4 = 800 sccm:30 sccm:45 sccm.
[0078] 3.7 Cool down by shutting off the carbon source and hydrogen gas, and then cool to room temperature under an argon protective atmosphere.
[0079] The graphene film on the ring surface prepared in Comparative Example 2 was characterized. Its optical microscope image is shown below. Figure 5 As shown. By Figure 5 It is known that if the carbon-hydrogen ratio is too high during growth, the graphene film will be too thick, wrinkles will form during annealing, and the graphene film will easily fall off.
[0080] The coated ring prepared in Comparative Example 2 was characterized. An optical microscope image of this ring is shown below. Figure 7 As shown. By Figure 6 It can be seen that the edges are very uneven, the graphene film is relatively thick, and multiple islands are formed.
[0081] Comparative Example 3 (the ring axis is parallel to the airflow direction, no hydrogen is generated during the heating process, and no graphene grows): 1. Pretreatment: The molding ring is ultrasonically cleaned with ethanol to ensure that the surface of the molding ring is absolutely clean.
[0082] 2. Placement of the tungsten carbide shaped ring: Place the tungsten carbide shaped ring vertically in the glass plate carrier, with the plane of the glass plate carrier parallel to the airflow direction, that is, the axial direction of the shaped ring is parallel to the airflow direction.
[0083] 3. CVD growth: (Comparison of the effects of adding or not adding hydrogen during the heating process on the material) 3.1 Place the carrier containing the molding ring in the constant temperature zone of the CVD furnace, ensuring that the gas inlet direction of the CVD furnace is parallel to the axis of the molding ring.
[0084] 3.2 Evacuate the chamber to a vacuum state to remove all air from the CVD furnace.
[0085] 3.3 Fill the cavity with argon gas to atmospheric pressure.
[0086] 3.4 Heat up from room temperature to the target temperature of 1020℃ in 100 minutes, and introduce 800 sccm Ar.
[0087] 3.5 Cooling: Reduce the temperature to room temperature under an argon protective atmosphere.
[0088] Comparative Example 4 (the annular axis is parallel to the airflow direction, the heating process is hydrogen-rich, and no graphene grows): 1. Pretreatment: The molding ring is ultrasonically cleaned with ethanol to ensure that the surface of the molding ring is absolutely clean.
[0089] 2. Placement of the tungsten carbide shaped ring: Place the tungsten carbide shaped ring vertically in the glass plate carrier, with the plane of the glass plate carrier parallel to the airflow direction, that is, the axial direction of the shaped ring is parallel to the airflow direction.
[0090] 3. CVD growth: (Comparison of the effects of adding or not adding hydrogen during the heating process on the material) 3.1 Place the carrier containing the molding ring in the constant temperature zone of the CVD furnace, ensuring that the gas inlet direction of the CVD furnace is parallel to the axis of the molding ring.
[0091] 3.2 Evacuate the chamber to a vacuum state to remove all air from the CVD furnace.
[0092] 3.3 Fill the cavity with argon gas to atmospheric pressure.
[0093] 3.4 Heat up from room temperature to the target temperature of 1020℃ in 100 min, and introduce 800 sccm Ar and 100 sccm H2.
[0094] 3.5 Cool down, turn off the hydrogen gas, and cool to room temperature under an argon protective atmosphere.
[0095] Comparative Example 5 (The annulus axis is parallel to the gas flow direction; no hydrogen is present during the heating process, but the growth stage is rich in hydrogen): 1. Pretreatment: The tungsten carbide ring is ultrasonically cleaned with ethanol to ensure that the surface of the ring is absolutely clean.
[0096] 2. Placement of the tungsten carbide shaped ring: Place the tungsten carbide shaped ring vertically in the glass plate carrier, with the plane of the glass plate carrier parallel to the airflow direction, that is, the axial direction of the shaped ring is parallel to the airflow direction.
[0097] 3. CVD growth: 3.1 Place the carrier containing the molding ring in the constant temperature zone of the CVD furnace, ensuring that the gas inlet direction of the CVD furnace is parallel to the axis of the molding ring.
[0098] 3.2 Evacuate the chamber to a vacuum state to remove all air from the CVD furnace.
[0099] 3.3 Fill the cavity with argon gas to atmospheric pressure.
[0100] 3.4 Heat up from room temperature to the target temperature of 1020℃ in 100 minutes, and introduce 800 sccm Ar.
[0101] 3.5 Incubate at the growth temperature for 30 minutes after reaching the growth temperature.
[0102] 3.6 Growth: Methane was used as the carbon source, and hydrogen was used as the reducing gas. The growth time was 300 min; Ar:H2:CH4 = 800 sccm:180 sccm:45 sccm.
[0103] 3.7 Cool down by shutting off the carbon source and hydrogen gas, and then cool to room temperature under an argon protective atmosphere.
[0104] To investigate the effect of introducing hydrogen gas during the heating process on the mechanical properties of the tungsten steel substrate and to evaluate the protective effect of the graphene coating, nanoindentation mechanical tests were performed on the surfaces of the original tungsten steel rings, the rings treated with Example 1 (hydrogen-poor graphene growth), Comparative Example 2 (hydrogen-free graphene growth), Comparative Example 3 (heating without hydrogen, no graphene growth), and Comparative Example 4 (heating with hydrogen, no graphene growth). The results are as follows: Figure 7 As shown.
[0105] The original tungsten carbide ring had the highest surface hardness, approximately 7.60 GPa. The graphene-coated ring prepared using the method of Example 1 of this invention (hydrogen-free heating process, hydrogen-poor growth stage) had a surface hardness of 5.89 GPa, which, although lower than the original substrate, remained at a relatively high level. The surface hardness of the ring in Comparative Example 3 (heating only, no hydrogen treatment, no graphene growth) significantly decreased to 3.60 GPa, indicating that high-temperature heat treatment itself has a softening effect on the tungsten carbide surface. However, the surface hardness of the ring in Comparative Example 4 (hydrogen-rich heating process, no graphene growth) dropped sharply to 1.23 GPa. This directly confirms that at high temperatures, hydrogen reacts with the tungsten carbide on the tungsten carbide surface, severely damaging the substrate surface structure and leading to a significant deterioration in mechanical properties.
[0106] Comparing the results of Example 1 and Comparative Example 4, it can be seen that the hydrogen-deficient process adopted in this invention, which involves "not introducing reducing gas (hydrogen) during the heating process," effectively avoids substrate damage caused by high-temperature hydrogen corrosion, which is key to maintaining the overall mechanical properties and service life of the coated ring. Meanwhile, the hardness of the coated ring in Example 1 (5.89 GPa) is significantly higher than that in Comparative Example 3 (3.60 GPa), indicating that the in-situ grown graphene film provides good reinforcement and protection for the heat-softened substrate surface.
[0107] The present invention has been described in detail above. For those skilled in the art, the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. Although specific embodiments have been given, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein. Some of the essential features can be applied within the scope of the following appended claims.
Claims
1. A coated ring for optical lens fabrication, comprising a tungsten carbide ring and a graphene film deposited on the surface of the tungsten carbide ring.
2. The coated ring for optical lens processing according to claim 1, characterized in that: The graphene film is prepared by chemical vapor deposition.
3. The coated ring for optical lens processing according to claim 1 or 2, characterized in that: The surface of the ring includes the precision-molded inner wall surface of the ring and the contact surface with the upper and lower molds.
4. A method for preparing a coated ring for optical lens fabrication, comprising the following steps: 1) Clean the tungsten carbide ring to ensure its surface is clean; 2) Place the tungsten carbide ring vertically in the carrier; 3) Place the carrier containing the tungsten carbide ring in the isothermal zone of a chemical vapor deposition (CVD) furnace, ensuring that the CVD furnace inlet direction is parallel to the axis of the tungsten carbide ring; in an atmosphere containing carbon source and hydrogen, grow graphene on the surface of the ring using chemical vapor deposition; wherein, During the chemical vapor deposition process, the ambient temperature is raised to the graphene growth temperature before the carbon source is introduced, and no reducing gas is introduced during the heating process; in the atmosphere containing carbon source and hydrogen, the carbon-hydrogen ratio (flow rate ratio) of carbon source and hydrogen is: 1:1 ≥ carbon-hydrogen ratio ≥ 1:
3.
5. The preparation method according to claim 4, characterized in that: In step 3), the carbon source is selected from at least one of the following: methane, propane, acetylene, ethylene, and ethanol.
6. The preparation method according to claim 4 or 5, characterized in that: In step 3), during the chemical vapor deposition process, the input flow rate of the carbon source is 30-100 sccm, and the input flow rate of the reducing gas is 30-300 sccm.
7. The preparation method according to any one of claims 4-6, characterized in that: In step 3), during the chemical vapor deposition process, a carrier gas is also introduced, and the carrier gas is selected from at least one of the following: argon and nitrogen. The input flow rate of the carrier gas is 100 to 1000 sccm.
8. The preparation method according to any one of claims 4-7, characterized in that: In step 3), the growth temperature of graphene during the chemical vapor deposition process is 800–1080℃, and the growth time is 200–500 min.
9. The preparation method according to any one of claims 4-8, characterized in that: In step 3), during the chemical vapor deposition process, after the ambient temperature is raised to the graphene growth temperature and maintained at the growth temperature for 5-30 minutes, the carbon source is introduced.
10. An optical lens molding die, comprising a coated ring according to any one of claims 1-3 or a coated ring prepared by the method according to any one of claims 4-9.