PVD multi-arc plating process for solving difficult release of carbon fiber hot press molding

Abstract

The present application relates to the technical field of surface engineering, and particularly relates to a PVD multi-arc coating process for solving the difficult demolding of carbon fiber hot press forming. 3×10‑3Pa Under the conditions of workpiece revolution and rotation, a Cr transition layer, a CrN buffer layer and a CrAlN support layer are sequentially deposited, and TiAlN and CrAlN nano-multilayer modulation structures with a period ratio of 1:5 are alternately deposited; after coating, vacuum annealing at 350 DEG C is carried out, and then PFPE gas phase deposition passivation is implemented to reduce surface energy. The present application has the advantages of low friction, low surface energy, high temperature resistance, wear resistance and corrosion resistance, can significantly reduce the demolding force and improve the service life of the mold.

Description

[Technical Field] This invention relates to the field of surface engineering technology, and in particular to a PVD multi-arc coating process for solving the problem of difficult demolding in carbon fiber hot pressing. [Background Technology] Carbon fiber composites, due to their lightweight and high strength, are increasingly widely used in high-end manufacturing fields such as aerospace and new energy vehicles. Their molding process often employs hot pressing technology at 180-300℃. However, during hot pressing, the epoxy resin melt in the carbon fiber prepreg is highly susceptible to chemical adhesion to the mold cavity surface, leading to difficulties in demolding. This not only severely impacts production efficiency but may also damage the surface of carbon fiber products, reducing product quality.

[0003] To solve the problem of difficult demolding, traditional methods mainly rely on coating the mold surface with silicone-based release agents. However, these release agents usually need to be applied frequently before each molding, increasing the process and time costs; release agent residue may contaminate the surface of the product, affecting subsequent bonding, spraying and other secondary processing; long-term use may also lead to a decline in the surface performance of the mold.

[0004] Physical vapor deposition (PVD) technology, especially multi-arc ion plating, has been widely studied for its ability to produce coatings with strong adhesion, high hardness, and good wear resistance. However, for the specific application of carbon fiber hot pressing molds, a PVD coating process that can simultaneously meet the requirements of extremely low coefficient of friction, low surface energy, resistance to high-temperature chemical corrosion, and ultra-long service life still needs further development and optimization. [Summary of the Invention] To overcome the above problems, this invention proposes a PVD multi-arc coating process that can effectively solve the problem of difficult demolding in carbon fiber hot pressing. By preparing a composite coating with a specific nano-multilayer structure on the mold surface, a durable and efficient demolding effect is achieved, while ensuring the coating's high temperature resistance, wear resistance, and corrosion resistance.

[0006] The present invention provides a technical solution to the above-mentioned technical problems: a PVD multi-arc coating process for solving the problem of difficult demolding in carbon fiber hot pressing, comprising the following steps: Step S1, Substrate Pretreatment: Hot work die steel is selected as the substrate material; the surface of the mold cavity is mirror polished to make the surface roughness Ra≤0.1μm; the polished mold is ultrasonically cleaned with alcohol and acetone in sequence; the cleaned mold is placed in the vacuum chamber of the PVD coating equipment for ion etching treatment, Ar gas is introduced at 50sccm, a bias voltage of -900V is applied, and etching is performed for 40 minutes to clean and activate the mold surface.

[0007] Step S2, Coating System Configuration: Evacuate the vacuum chamber to a base vacuum of ≤3×10⁻⁶. -3The vacuum system employs a combination of molecular and mechanical pumps; the chamber is equipped with 6 cathode arc sources, including 2 sets of Cr80 and Al20 alloy targets, 2 sets of pure Cr targets, and 2 sets of Ti50 and Al50 alloy targets; the workpiece holder adopts a combination of revolution and rotation, with a revolution speed of 3 rpm and a rotation speed of 2 rpm to ensure uniform deposition.

[0008] Step S3, Deposition process: Sequentially deposit a Cr transition layer, a CrN buffer layer, a CrAlN support layer, and TiAlN and CrAlN nanomodulation layers. The TiAlN and CrAlN nanomodulation layers are formed by alternately activating TiAl alloy targets and CrAl alloy targets with a cycle ratio of 1:5 and a total thickness of approximately 3 μm, in order to prevent crack propagation and impart high-temperature oxidation resistance to the coating.

[0009] Step S4, Post-treatment: After the coating is completed, argon gas is introduced into the vacuum chamber for protection, the temperature is raised to 350℃ and held for 4 hours for vacuum annealing to eliminate the internal stress of the coating; then, perfluoropolyether (PFPE) vapor deposition treatment is performed on the mold surface to form an ultra-thin passivation film to further reduce the surface energy and improve the demolding effect.

[0010] Preferably, the deposition parameters of the Cr transition layer in S3 are as follows: start the Cr target arc source, target current 65A, bias voltage -120V, and deposit for 15 minutes to form a dense metallic Cr transition layer to improve the adhesion between the coating and the substrate, so that the adhesion is >80N; Preferably, the deposition parameters of the CrN buffer layer in S3 are: introducing N2 gas at 180 sccm and applying a pulsed bias voltage of -100V to form the CrN buffer layer to achieve stress gradient transition; Preferably, the deposition parameters of the CrAlN support layer in S3 are as follows: start the Cr80 and Al20 alloy target arc source, target current 70A, N2 gas 250sccm, and deposit a CrAlN support layer with a thickness of about 2μm to provide the main support and wear resistance properties.

[0011] Preferably, the deposition parameters for the TiAlN and CrAlN nanomodulation layers in S3 are as follows: alternating activation of Ti50 and Al50 alloy targets (current 55A) and Cr80 and Al20 alloy targets (current 70A), N2 gas at 250 sccm, and forming a TiAlN and CrAlN nanomultilayer modulation structure with a period ratio of 1:5 by controlling the deposition time.

[0012] Compared with existing technologies, the PVD multi-arc coating process of this invention, used to solve the problem of difficult demolding in carbon fiber hot pressing, constructs a specific CrAlN and TiAlN nano-multilayer structure and combines it with PFPE surface passivation. The coating achieves a friction coefficient as low as <0.18 and a surface energy of <35mN / m under 400℃ testing conditions, resulting in a durable low-adhesion demolding effect. According to ASTM D3330 standard testing, the demolding force is reduced by more than 72% compared with the untreated mold. The service life can reach more than 28,000 cycles under continuous hot pressing at 200℃. It eliminates the need for traditional release agents, avoids residual pollution, improves production efficiency, and the surface roughness Ra of the product can be stabilized in the range of 0.6-0.8μm. [Attached Image Description] Figure 1 This is a flowchart of the PVD multi-arc coating process used in this invention to solve the problem of difficult demolding in carbon fiber hot pressing.

Detailed Implementation Methods

[0015] It should be noted that in the embodiments of the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are limited to relative positions on the specified view, rather than absolute positions.

[0016] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0017] Please see Figure 1 The PVD multi-arc coating process of the present invention for solving the problem of difficult demolding in carbon fiber hot pressing includes the following steps: Step S1, Substrate Pretreatment: Hot work die steel is selected as the mold substrate. The surface of the mold cavity is mirror polished to make the surface roughness Ra less than or equal to 0.1μm. The mold is then ultrasonically cleaned with alcohol and acetone in sequence. The mold is placed in the vacuum chamber of the PVD coating equipment, Ar gas is introduced at 50sccm, a bias voltage of -900V is applied, and ion etching is performed for 40 minutes. Step S2, Coating System Configuration: Evacuate the vacuum chamber to a base vacuum of less than or equal to 3 × 10⁻⁶. -3Pa; equipped with 6 cathode arc sources, including 2 sets of Cr80 and Al20 alloy targets, 2 sets of pure Cr targets and 2 sets of Ti50 and Al50 alloy targets; the workpiece holder adopts a combination of revolution and rotation, with a revolution speed of 3 rpm and a rotation speed of 2 rpm; Step S3, Deposition: Sequentially deposit a Cr transition layer, a CrN buffer layer, a CrAlN support layer, and a TiAlN and CrAlN nanomodulation layer on the surface of the mold. The TiAlN and CrAlN nanomodulation layer forms a nano-multilayer modulation structure with a period ratio of 1:5 by alternately activating the TiAl alloy target and the CrAl alloy target, with a total thickness of about 3 μm. Step S4, Post-processing: Argon gas is introduced into the vacuum chamber for protection, the temperature is raised to 350℃ and held for 4 hours for vacuum annealing; then perfluoropolyether (PFPE) vapor deposition is performed on the mold surface to form a passivation film.

[0018] The hot work die steel is H13 or DIEVAR.

[0019] The deposition parameters for the Cr transition layer are as follows: start a pure Cr target arc source, target current 65A, workpiece bias voltage -120V, deposition for 15 minutes to form a metallic Cr transition layer.

[0020] The deposition parameters for the CrN buffer layer are as follows: after depositing the Cr transition layer, N2 gas is introduced at 180 sccm, and a pulsed bias voltage of -100V is applied to deposit and form the CrN buffer layer.

[0021] The deposition parameters for the CrAlN support layer are as follows: start the Cr80 and Al20 alloy target arc source, target current 70A, N2 gas 250sccm, and deposit a CrAlN support layer with a thickness of about 2μm.

[0022] The deposition parameters for the TiAlN and CrAlN nanomodulation layers are as follows: Ti50 and Al50 alloy target arc sources and Cr80 and Al20 alloy target arc sources are activated simultaneously; the current of the Ti50 and Al50 alloy target arc sources is 55A; the current of the Cr80 and Al20 alloy target arc sources is 70A; the N2 gas concentration is 250 sccm; and the workpiece bias voltage is -60V.

[0023] The alternating deposition of TiAlN and CrAlN is achieved by controlling the arc source switching time. The TiAlN deposition time is 2 seconds, the CrAlN deposition time is 10 seconds, and one cycle is 12 seconds.

[0024] The total deposition time of the nano-modulation layer is 150 minutes, forming a nano-multilayer modulation structure with a total thickness of approximately 3 μm.

[0025] The vacuum annealing process involves holding the temperature at 350°C for 4 hours.

[0026] The processing time for the PFPE vapor deposition process is 30 minutes.

[0027] The present invention will be further described below with reference to the embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0028] Example 1 A PVD multi-arc coating process for solving the problem of difficult demolding in carbon fiber hot pressing is described in the following steps: (1) Substrate pretreatment: H13 hot work die steel was selected as the substrate of the mold to be treated; the surface of the mold cavity was precision ground and polished to achieve a mirror effect with a surface roughness Ra=0.08μm; the mold was placed in an ultrasonic cleaner, first cleaned with alcohol for 15 minutes, then cleaned with acetone for 15 minutes, and then dried with clean nitrogen; the dried mold was installed on the workpiece rack of the PVD multi-arc coating equipment, the vacuum chamber was closed, and the vacuum pump group was started to evacuate the background vacuum to 2.5×10 -3 Pa, and heated to 450℃; Ar gas was introduced at 50 sccm, and a DC bias of -900V was applied to the workpiece for ion etching cleaning for 40 minutes.

[0029] (2) Deposition of Cr transition layer: After etching, adjust the Ar gas flow rate to 30 sccm, start the pure Cr target arc source, target current 65A, workpiece bias voltage -120V, deposit for 15 minutes to form a metal Cr transition layer with a thickness of about 0.5μm.

[0030] (3) Deposition of CrN buffer layer: On the basis of Cr transition layer, N2 gas is introduced at 180 sccm, the workpiece bias voltage is adjusted to -100V (pulse mode), and Cr target arc source (current 65A) is used to deposit for 10 minutes to form CrN buffer layer.

[0031] (4) Deposition of CrAlN support layer: Turn off the pure Cr target arc source, start the Cr80 and Al20 alloy target arc source, target current 70A, increase N2 gas flow rate to 250sccm, workpiece bias voltage -80V, deposit for 60 minutes to form a CrAlN support layer with a thickness of about 2μm.

[0032] (5) Deposition of TiAlN and CrAlN nanomodulation layers: Simultaneously start the Ti50 / Al50 alloy target arc source (current 55A) and the Cr80 and Al20 alloy target arc source (current 70A), maintain the N2 gas flow rate at 250sccm, and the workpiece bias voltage at -60V; achieve alternating deposition of TiAlN and CrAlN by controlling the arc source switching time, wherein the TiAlN deposition time is 2 seconds, the CrAlN deposition time is 10 seconds, one cycle is 12 seconds, and the total deposition time is 150 minutes, forming a nano-multilayer modulation structure with a total thickness of about 3μm.

[0033] (6) Post-treatment: After the coating is completed, turn off all arc sources and gases, and introduce high-purity argon into the vacuum chamber to atmospheric pressure; cool the chamber to 350°C and keep it at that temperature for 4 hours for vacuum annealing; after annealing, wait for the mold to cool to room temperature and take it out; place the mold in a vapor deposition equipment for perfluoropolyether (PFPE) passivation treatment for 30 minutes.

[0034] Performance Testing: The coating mold obtained in Example 1 was subjected to performance testing, and the results are as follows: On a UMT-3 friction and wear testing machine, using Si3N4 ceramic balls as the grinding media, the average friction coefficient was 0.16 under a load of 5N and a sliding speed of 0.1m / s at 400℃. The surface energy was calculated to be 32mN / m using the Owens-Wendt method with a contact angle measuring instrument. The demolding force was tested under hot pressing conditions at 200℃ according to ASTM D3330 standard, and the demolding force was 18N, which is 72.3% lower than the 65N of the uncoated mold. The life test was conducted under continuous hot pressing at 200℃. After 28,000 demolding cycles, there were no obvious signs of wear or failure on the coating surface, and the demolding performance remained stable. The surface roughness Ra of the molded carbon fiber product was stable at approximately 0.7μm, and the surface was clean and free of release agent residue.

[0035] Compared with existing technologies, the PVD multi-arc coating process of this invention, used to solve the problem of difficult demolding in carbon fiber hot pressing, constructs a specific CrAlN and TiAlN nano-multilayer structure and combines it with PFPE surface passivation. The coating achieves a friction coefficient as low as <0.18 and a surface energy of <35mN / m under 400℃ testing conditions, resulting in a durable low-adhesion demolding effect. According to ASTM D3330 standard testing, the demolding force is reduced by more than 72% compared with the untreated mold. The service life can reach more than 28,000 cycles under continuous hot pressing at 200℃. It eliminates the need for traditional release agents, avoids residual pollution, improves production efficiency, and the surface roughness Ra of the product can be stabilized in the range of 0.6-0.8μm.

[0036] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any modifications, equivalent substitutions and improvements made within the concept of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A PVD multi-arc coating process for solving the problem of difficult demolding in carbon fiber hot pressing, characterized in that, Includes the following steps: Step S1, Substrate Pretreatment: Hot work die steel is selected as the mold substrate. The surface of the mold cavity is mirror polished to make the surface roughness Ra less than or equal to 0.1μm. The mold is then ultrasonically cleaned with alcohol and acetone in sequence. The mold is placed in the vacuum chamber of the PVD coating equipment, Ar gas is introduced at 50sccm, a bias voltage of -900V is applied, and ion etching is performed for 40 minutes. Step S2, Coating System Configuration: Evacuate the vacuum chamber to a base vacuum of less than or equal to 3 × 10⁻⁶. -3 Pa; equipped with 6 cathode arc sources, including 2 sets of Cr80 and Al20 alloy targets, 2 sets of pure Cr targets and 2 sets of Ti50 and Al50 alloy targets; the workpiece holder adopts a combination of revolution and rotation, with a revolution speed of 3 rpm and a rotation speed of 2 rpm; Step S3, Deposition: Sequentially deposit a Cr transition layer, a CrN buffer layer, a CrAlN support layer, and a TiAlN and CrAlN nanomodulation layer on the surface of the mold. The TiAlN and CrAlN nanomodulation layer forms a nano-multilayer modulation structure with a period ratio of 1:5 by alternately activating the TiAl alloy target and the CrAl alloy target, with a total thickness of about 3 μm. Step S4, Post-processing: Argon gas is introduced into the vacuum chamber for protection, the temperature is raised to 350℃ and held for 4 hours for vacuum annealing; then perfluoropolyether (PFPE) vapor deposition is performed on the mold surface to form a passivation film.

2. The PVD multi-arc coating process for solving the problem of difficult demolding in carbon fiber hot pressing as described in claim 1, characterized in that, The hot work die steel is H13 or DIEVAR.

3. The PVD multi-arc coating process for solving the difficulty of demolding carbon fiber hot pressing as described in claim 1, characterized in that, The deposition parameters for the Cr transition layer are as follows: start a pure Cr target arc source, target current 65A, workpiece bias voltage -120V, deposition for 15 minutes to form a metallic Cr transition layer.

4. The PVD multi-arc coating process for solving the problem of difficult demolding in carbon fiber hot pressing as described in claim 1, characterized in that, The deposition parameters for the CrN buffer layer are as follows: after depositing the Cr transition layer, N2 gas is introduced at 180 sccm, and a pulsed bias voltage of -100V is applied to deposit and form the CrN buffer layer.

5. The PVD multi-arc coating process for solving the difficulty of demolding carbon fiber hot pressing as described in claim 1, characterized in that, The deposition parameters for the CrAlN support layer are as follows: start the Cr80 and Al20 alloy target arc source, target current 70A, N2 gas 250sccm, and deposit a CrAlN support layer with a thickness of about 2μm.

6. The PVD multi-arc coating process for solving the difficulty of demolding carbon fiber hot pressing as described in claim 1, characterized in that, The deposition parameters for the TiAlN and CrAlN nanomodulation layers are as follows: Ti50 and Al50 alloy target arc sources and Cr80 and Al20 alloy target arc sources are activated simultaneously; the current of the Ti50 and Al50 alloy target arc sources is 55A; the current of the Cr80 and Al20 alloy target arc sources is 70A; the N2 gas concentration is 250 sccm; and the workpiece bias voltage is -60V.

7. The PVD multi-arc coating process for solving the problem of difficult demolding in carbon fiber hot pressing as described in claim 6, characterized in that, The alternating deposition of TiAlN and CrAlN is achieved by controlling the arc source switching time. The TiAlN deposition time is 2 seconds, the CrAlN deposition time is 10 seconds, and one cycle is 12 seconds.

8. The PVD multi-arc coating process for solving the problem of difficult demolding in carbon fiber hot pressing as described in claim 7, characterized in that, The total deposition time of the nano-modulation layer is 150 minutes, forming a nano-multilayer modulation structure with a total thickness of approximately 3 μm.

9. The PVD multi-arc coating process for solving the difficulty of demolding carbon fiber hot pressing as described in claim 1, characterized in that, The vacuum annealing process involves holding the temperature at 350°C for 4 hours.

10. The PVD multi-arc coating process for solving the problem of difficult demolding in carbon fiber hot pressing as described in claim 1, characterized in that, The processing time for the PFPE vapor deposition process is 30 minutes.

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