WO2019144409A1 - 一种仿生复合减阻表面及其制备方法 - Google Patents

一种仿生复合减阻表面及其制备方法 Download PDF

Info

Publication number
WO2019144409A1
WO2019144409A1 PCT/CN2018/074465 CN2018074465W WO2019144409A1 WO 2019144409 A1 WO2019144409 A1 WO 2019144409A1 CN 2018074465 W CN2018074465 W CN 2018074465W WO 2019144409 A1 WO2019144409 A1 WO 2019144409A1
Authority
WO
WIPO (PCT)
Prior art keywords
drag reducing
reducing surface
substrate
texture
corrugated structure
Prior art date
Application number
PCT/CN2018/074465
Other languages
English (en)
French (fr)
Inventor
余锦
貊泽强
代守军
王金舵
何建国
Original Assignee
中国科学院光电研究院
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 中国科学院光电研究院 filed Critical 中国科学院光电研究院
Priority to PCT/CN2018/074465 priority Critical patent/WO2019144409A1/zh
Publication of WO2019144409A1 publication Critical patent/WO2019144409A1/zh

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
    • B81B7/04—Networks or arrays of similar microstructural devices

Definitions

  • the present disclosure relates to the field of fluid dynamics technology, and in particular, to a biomimetic composite drag reducing surface and a preparation method thereof.
  • the shark is a swimming swimmer in the ocean. Its cruising speed in the water is about 5kph, and it can instantaneously erupt to 70kph when chasing prey. In addition to its standard streamlined shape, shark's high speed is closely related to its special scale structure.
  • the shark's skin has a certain shape of groove texture.
  • the groove texture reduction technology was developed by studying the characteristics of shark skin.
  • the trench texture drag reduction technology was launched in the 1980s and has entered the practical stage of engineering. Airbus has put 70% of the surface area of the A320 tester on the grooved film and found that it can save 1% to 2% of fuel. effect.
  • the NASA Langley Center achieved a 6% drag reduction effect on the flight test of the Learnjet aircraft.
  • the present disclosure provides a biomimetic composite drag reducing surface and a preparation method thereof to further improve fluid drag reduction effect and improve the range of the aircraft.
  • the present disclosure discloses a biomimetic composite drag reducing surface comprising: a substrate having a drag reducing surface; a convex structure formed on the drag reducing surface, the raised structures forming on the surface of the trench a trench texture; a superhydrophobic surface texture formed on an upper surface and/or a side of the raised structure, the superhydrophobic surface texture comprising: a periodic corrugated structure formed on an upper surface and/or a side of the raised structure, and A low surface energy coating applied to the corrugations of the periodic corrugated structure.
  • the width of the trench in the trench texture is between 120 ⁇ m and 500 ⁇ m; the period T of the corrugation in the periodic corrugated structure is greater than 100 nm and less than 1200 nm.
  • the groove texture is a staggered groove texture formed by a raised array; the raised structure in the raised array is one or more of the following protrusions: a columnar protrusion, Tapered protrusion, outer serrated protrusion or semi-circular protrusion.
  • the raised structures in the raised array are columnar bumps that satisfy the Cassie model equation:
  • a is the convex width of the columnar protrusion
  • b is the gap between the adjacent two columnar protrusions in the same row
  • ⁇ e is the intrinsic contact angle of the material of the drag reducing surface of the substrate.
  • the convex structure in the convex array is a columnar protrusion having a rectangular cross section; wherein, in the Cassie model equation, 5 ⁇ m ⁇ a ⁇ 30 ⁇ m; 120 ⁇ m ⁇ b ⁇ 500 ⁇ m, 100 ⁇ m ⁇ l ⁇ 200 ⁇ m , h ⁇ 15 ⁇ m, wherein l and h are the length and height of the columnar protrusion, respectively.
  • the depth of the corrugations in the periodic corrugated structure is between 10 nm and 100 nm.
  • the corrugations in the periodic corrugated structure are also covered with nanostructures, which are one or more of the following structures: nanopores, nanoflocs, nanoprojections.
  • the surface energy of the low surface energy coating material is less than 50 mJ/m 2 .
  • the low surface energy coating is a fluorosilane, silicone or self-assembling molecular film.
  • the substrate is a planar two-dimensional material, a curved two-dimensional material, or a three-dimensional structure; and/or the substrate is a rigid material or an organic flexible material.
  • the substrate is a three-dimensional structure of an aluminum alloy material or a titanium alloy material.
  • the substrate is a two-dimensional flexible material; the other surface of the substrate other than the drag reducing surface is coated with an adhesive.
  • the present disclosure also discloses a method for preparing a biomimetic composite drag reducing surface, comprising: forming a convex structure on a drag reducing surface, the convex structures forming a groove texture on the drag reducing surface; The upper surface and/or the side surface of the raised structure on both sides of the groove in the groove texture form a periodic corrugated structure; and the surface of the corrugation in the periodic corrugated structure covers the low surface energy coating.
  • the array of bumps is processed on the drag reducing surface by ultrashort pulse laser cold ablation, which forms a staggered trench texture on the drag reducing surface.
  • an ultrashort pulsed laser beam is used to illuminate over the array of bumps to obtain a periodic corrugated structure at the top of the raised structure.
  • the drag reducing surface is a titanium alloy drag reducing surface; irradiating with an ultrashort pulse laser beam over the bump array to obtain a periodic corrugated structure at the top of the raised structure, irradiating
  • the energy density is between 109 mJ/cm 2 and 196.5 mJ/cm 2 .
  • covering the substrate drag reducing surface with a low surface energy coating comprises: preparing a solution of the low surface energy material; transferring the solution of the low surface energy material to the drag reducing surface of the substrate, after drying The low surface energy material covers the corrugated surface of the periodic corrugated structure to form a low surface energy coating.
  • the solution of the low surface energy material is a solution of fluorosilane in ethanol, wherein the concentration of the solute fluorosilane is between 0.5 wt.% and 6 wt.%.
  • the superhydrophobic drag reducing surface is prepared at the wing of the aircraft and the tail wing, it can prevent icing and solve the problems caused by icing on the flight of the aircraft;
  • FIG. 1 is a schematic illustration of a staggered groove texture structure on a substrate of a biomimetic composite drag reducing surface in accordance with an embodiment of the present disclosure.
  • 2A and 2B are schematic illustrations of continuous groove texture and segmented groove texture on a drag reducing surface, respectively.
  • FIG 3 is an enlarged view of a portion of a periodic raised corrugated structure of a columnar protrusion of a bionic composite drag reducing surface in accordance with an embodiment of the present disclosure.
  • FIG. 4 is a flow chart of a method for preparing a bionic composite drag reducing surface of an embodiment of the present disclosure.
  • the applicant gradually realized that the space for improvement of the drag reduction effect is limited by simply relying on the bionic shark groove structure.
  • a biomimetic composite drag reducing surface is provided.
  • the bionic composite drag reducing surface of this embodiment includes:
  • a superhydrophobic surface texture formed on an upper surface and/or a side of the raised structure, the superhydrophobic surface texture comprising: a periodic corrugated structure formed on an upper surface and/or a side of the raised structure and coated in the cycle Low surface energy coating on corrugated structure corrugations.
  • the groove texture and the super-hydrophobic surface texture are combined organically, and the respective advantages and synergies are exerted, thereby greatly improving the drag reduction performance.
  • the substrate may be a two-dimensional rigid material or a two-dimensional organic flexible material.
  • the interlaced groove texture and the periodic corrugated structure are prepared by laser processing, and the substrate is made of aluminum alloy, titanium alloy and other materials which are easy to be laser processed.
  • the substrate is not necessarily a planar two-dimensional material, but also a curved two-dimensional material or a three-dimensional structure.
  • the substrate is a friction-producing surface in contact with the fluid of the aircraft, for example, the application of the present disclosure is applied to the ship, and the substrate is the surface of the ship in contact with water.
  • the two-dimensional substrate is coated with an adhesive on the other surface of the drag reducing surface and is adhered with a protective film.
  • the biofilm composite drag reducing surface can be conveniently adhered to the desired surface by tearing off the protective film.
  • FIG. 1 is a schematic illustration of a staggered groove texture on a substrate of a biomimetic composite drag reducing surface in accordance with an embodiment of the present disclosure.
  • (a) is a cross-sectional view of the interlaced groove texture
  • (b) is a top view of the staggered groove texture.
  • an array of columnar projections is formed on the drag reducing surface of the substrate, the array forming a staggered groove texture of the drag reducing surface.
  • the cross-sectional shape is a rectangle, the protrusion width a, the gap between the adjacent two columnar protrusions in the same row is b, the protrusion width a and the gap b satisfy the Cassie model equation, and ⁇ e is the intrinsic Contact angle:
  • the intrinsic contact angle varies with the material of the drag reducing surface of the substrate. Taking the titanium alloy as an example, the intrinsic contact angle is 113°, the width of the protrusion a, and the range of the gap b is: 5 ⁇ m ⁇ a ⁇ 30 ⁇ m; 120 ⁇ m ⁇ b ⁇ 500 ⁇ m.
  • the protrusions forming the staggered groove texture may also be columnar protrusions having a circular cross section. Even a tapered protrusion, an outer serrated protrusion or a semi-circular protrusion can also achieve the present disclosure.
  • groove texture such as continuous groove texture, as shown in Figure 2A, other than a staggered groove array of raised arrays; segmented groove texture, As shown in Figure 2B.
  • the black portion is a convex portion on the drag reducing surface.
  • the surface of each of the columnar protrusions is formed with a periodic corrugated structure in the staggered groove texture, and the period T of the periodic corrugated structure is greater than 100 nm and less than 1200 nm.
  • the periodic corrugated structure is prepared by a laser having a period of one laser wavelength ⁇ , for example, 532 nm, 1064 nm, or the like.
  • the depth of the periodic corrugated structure is related to the energy of the laser beam, between 10 nm and 100 nm.
  • FIG. 3 is an enlarged view of a portion of a periodic raised corrugated structure of a columnar protrusion of a bionic composite drag reducing surface in accordance with an embodiment of the present disclosure.
  • a periodic corrugated structure is formed on the upper surface of the columnar projection. The particles of the low surface energy coating adhere to the corrugations in the periodic corrugated structure.
  • the periodic corrugated structure in FIG. 3 is only formed on the upper surface of the columnar protrusion, in other embodiments of the present disclosure, the periodic corrugated structure may also be formed on the side of the protrusion. Since the periodic corrugation structure is prepared by using the laser beam, the side faces of the columnar projections are not exposed to the laser beam, so that no periodic corrugated structure is formed thereon. However, for other types of protrusions, such as serrated protrusions, a periodic corrugated structure is formed on both sides exposed to the laser beam.
  • LIPSS Laser Induced Periodical Surface Structure
  • the lower surface energy here refers to a surface energy of less than 50 mJ/m 2 .
  • a low surface energy coating such as a material containing a low surface energy element such as silicon or fluorine is coated on the drag reducing surface to reduce the resistance.
  • both fluorine-containing materials and siloxane materials have low surface energy, especially the surface energy of fluorine-containing materials is lower, and the more CF bonds, the smaller the surface free energy, so -CF3 groups
  • the group has a lower surface energy than the -CF2 group.
  • the reason may be that the spatial arrangement of the -CF3 group is tighter, the fluorine content in the corresponding unit area is increased, and the interaction between the fluorine atoms is small. The fluorine atom is more likely to migrate to the surface layer to lower the surface free energy.
  • Trifluorooctyltriethoxysilane (F 13 H 4 Si(OC 2 H 5 ) 3 , abbreviated as fluorosilane) has five -CF2 groups and one -CF3 group in the molecular structure, so it has a pole Low surface energy.
  • fluorosilane is applied as a low surface energy coating on the drag reducing surface.
  • a low surface energy coating such as a silicone or a self-assembling molecular film may be used to cover the drag reducing surface of the substrate.
  • the preparation method of the above biomimetic composite drag reducing surface is described below.
  • the superhydrophobic surface texture is processed on the groove texture of the bionic shark skin, and the groove texture and the superhydrophobic surface texture exert respective resistance reduction advantages, thereby achieving the purpose of reducing drag.
  • the preparation method of the bionic composite drag reducing surface of the embodiment includes:
  • Step A providing a substrate
  • the substrate may be a two-dimensional rigid material or an outer side steel plate of the ship itself or a flexible two-dimensional material. As long as it has a surface on which resistance reduction is required.
  • Step B processing a raised structure on the drag reducing surface of the substrate, the raised structures forming a groove texture on the drag reducing surface;
  • a columnar bump array is processed on the drag reducing surface of the substrate by ultrashort pulse laser cold ablation, and the bump array forms a bionic shark staggered groove texture.
  • Laser processing is non-contact processing, so it is noise-free and fast, and it can realize high-precision machining of various complex shapes without replacing the cutter head, without the usual tool wear and environmental friendliness.
  • Ultrashort pulse laser has gradually become the mainstream processing method of current fine manufacturing. Compared with other surface treatment methods, the core advantage of this method is that it can be applied to various types of materials, including organic materials, semiconductors, metals, etc., and is suitable for processing high precision and complex microstructures that cannot be realized by other processing methods. On the other hand, ultrashort pulse laser has the ability to simultaneously induce nanostructures while processing micron-scale structures, enabling one-time preparation of micro/nano composite structures.
  • the microstructure processing and modification of the material surface can be performed by the ultra-short pulse laser, and the effect of heat accumulation and conduction during the conventional long pulse laser processing can be overcome, and the precise micro-nano structure preparation effect can be obtained. .
  • Step C forming a periodic corrugated structure on the upper surface and/or the side surface of the convex structure on both sides of the groove in the groove texture;
  • an ultrashort pulse laser beam is directly irradiated over the bump array to obtain a Laser Induced Periodical Structure (LIPSS) at the top of the bump structure.
  • LIPSS Laser Induced Periodical Structure
  • the irradiation energy density should be between the ablation threshold (109 mJ/cm 2 ) and 196.5 mJ/cm 2 , and the period T of the corrugation is approximately equal to the laser wavelength ⁇ used.
  • the laser energy density is greater than the cauterization threshold.
  • the above LIPSS is generally considered to be formed by incident light and excited surface plasma interference. This interference results in periodic deposition of energy, which causes the metal surface to periodically melt and resolidify, ultimately forming a periodic surface structure.
  • the structural feature of the periodic corrugated structure is that the periodic fringe structure is covered with random nanostructures (expressed as nanopores, nanofloats, nanoprotrusions, etc.).
  • step D the surface of the corrugation in the periodic corrugated structure is covered with a low surface energy coating.
  • step D specifically includes:
  • Sub-step D1 preparing a 1 wt.% solution of fluorosilane in ethanol
  • the glass container is first placed on the electronic scale, and a certain amount of absolute ethanol is poured into the glass container; and the fluorosilane is slowly added dropwise to the absolute ethanol at a ratio of 1 wt.% to ensure that the fluorosilane is slowly added to the absolute ethanol.
  • the accuracy of the concentration of fluorosilane ethanol solution was placed on a magnetic stirrer and stirred at 200 r/min for 3 h to ensure that the fluorosilane was completely and uniformly dissolved in absolute ethanol.
  • the finished fluorosilane ethanol solution can also be purchased, and the weight percentage concentration thereof is from 0.5 wt.% to 6 wt.%, and is not limited to 1 wt.% in the above embodiment.
  • Sub-step D2 transferring the ethanol solution of fluorosilane to the drag reducing surface of the substrate and drying to cover the surface of the corrugated surface of the periodic corrugated structure.
  • the dried test piece is immersed in the configured 1 wt.% fluorosilane ethanol solution at room temperature for 2 h. Finally, it was placed in a constant temperature oven at a temperature of 120 ° C for 20 min. After drying, the particles of the low surface energy coating adhered to the corrugations in the periodic corrugated structure, as shown in FIG.
  • the ethanol solution of fluorosilane can be transferred to the drag reducing surface of the substrate by, for example, coating, evaporation, etc., in addition to drying, drying can also be used. Drying, infrared light irradiation or the like volatilizes the solvent ethanol in the ethanol solution of the fluorosilane on the drag reducing surface, leaving fluorosilane on the surface of the substrate drag reducing.
  • the drag reducing surface of the aircraft is super-hydrophobic and thus has icing-like properties, such as preparation of the surface at the wing of the aircraft and the tail fin, which not only has drag reducing performance, but also prevents icing and solves icing. Problems caused by aircraft flight.
  • the drag reducing surface of the aircraft is super-hydrophobic, so it has self-cleaning performance, which can be used on the bottom of marine crafts to prevent the adsorbed marine fouling organisms from reducing the speed of the aircraft, increasing the fuel consumption, increasing the number of docking times and time.
  • the application of the surface of the present invention can reduce the economic burden.
  • the drag reducing surface of the aircraft is super-hydrophobic, so it has anti-cavitation, can be used for marine propellers, improve the anti-cavitation ability of the blades, improve the propulsion efficiency, and prolong the life of the propeller.
  • the drag reducing surface of the aircraft has super-hydrophobicity, which has noise-reducing performance. It can be used on the surface of the aircraft to reduce the noise brought by navigation, and reducing noise is of great significance for enhancing the combat capability of the aircraft.
  • the present disclosure combines various drag reduction methods to exert respective drag reduction advantages, achieves the purpose of drag reduction enhancement, fuel economy, and can be used in various fields such as automobiles, airplanes, ships, rockets, etc., and has a good promotion. Value.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)

Abstract

一种仿生复合减阻表面及其制备方法。该仿生复合减阻表面包括：基材，其具有减阻表面；形成于所述减阻表面的沟槽织构；形成于沟槽织构的凸起结构的上表面和/或侧面的超疏水表面织构，该超疏水表面织构包括：周期波纹结构，以及涂覆于所述周期波纹结构波纹上的低表面能涂层。仿生复合减阻表面将多种减阻方法结合起来，发挥各自减阻优势，达到减阻增强、燃料节约的目的，可以用在汽车、飞机、船舶、火箭等各个领域，具有良好的推广应用价值。

Description

一种仿生复合减阻表面及其制备方法 技术领域
本公开涉及流体动力学技术领域，尤其涉及一种仿生复合减阻表面及其制备方法。
背景技术
高速运行的地面交通工具、飞行器及其它水中航行器，其能耗中有很大一部分需要用于克服流体介质的摩擦阻力。为了提高航行器的减阻性能，国内外专家学者及工程师作了大量的研究工作，从航行器的结构优化、表面织构设计等方面进行了大量的探索。
鲨鱼是海洋中的游泳健将，其在水中的巡游速度约为5kph，在追捕猎物时可瞬时爆发到70kph。鲨鱼的高游速除了与其标准的流线型形体有关外，还与其特殊的鳞片结构关系密切。
鲨鱼的表皮具有一定形状沟槽织构。通过研究鲨鱼表皮特征发展出沟槽织构减阻技术。沟槽织构减阻技术兴起于20世纪80年代，目前已进入了工程实用阶段，空中客车公司将A320试验机表面积的70％贴上沟槽薄膜，发现能够有1％～2％的节油效果。NASA兰利中心对Learnjet型飞机的飞行试验实现了6％的减阻效果。
公开内容
(一)要解决的技术问题
针对上述问题，本公开提供了一种仿生复合减阻表面及其制备方法，以进一步提高流体减阻效果，提高航行器的航程。
(二)技术方案
根据本公开的一个方面，本公开公开了一种仿生复合减阻表面，包括：基材，其具有减阻表面；形成于减阻表面的凸起结构，该些凸起结构在沟槽表面形成沟槽织构；形成于凸起结构的上表面和/或侧面的超疏水表面织构，该超疏水表面织构包括：形成于凸起结构的上表面和/或侧面的周期波纹结构，以及涂覆于周期波纹结构波纹上的低表面能涂层。
在本公开的一些实施例中，沟槽织构中沟槽的宽度介于120μm至500μm之间；周期波纹结构中波纹的周期T大于100nm，小于1200nm。
在本公开的一些实施例中，沟槽织构为由凸起阵列形成的交错沟槽织构；凸起阵列中的凸起结构为以下凸起中的一种或多种：柱状凸起、锥形凸起、外锯齿状凸起或半圆形凸起。
在本公开的一些实施例中，凸起阵列中的凸起结构为柱状凸起，满足Cassie模型方程：
arccos[-1+a/(a+b)·(cosθ e+1)]≥150°
其中，a为柱状凸起的凸起宽度，b为同排相邻两柱状凸起之间的间隙，θ e为基材的减阻表面的材料的本征接触角。
在本公开的一些实施例中，凸起阵列中的凸起结构为矩形横截面的柱状凸起；其中，Cassie模型方程中，5μm≤a≤30μm；120μm≤b≤500μm，100μm≤l≤200μm，h≥15μm，其中，l和h分别为柱状凸起的长度和高度。
在本公开的一些实施例中，周期波纹结构中波纹的深度介于10nm～100nm之间。
在本公开的一些实施例中，周期波纹结构中波纹上还覆盖有纳米结构，该纳米结构为以下结构中的一种或多种：纳米孔、纳米絮、纳米突出。
在本公开的一些实施例中，低表面能涂层的材料的表面能低于50mJ/m 2。
在本公开的一些实施例中，低表面能涂层为氟硅烷、硅氧烷或自组装分子膜。
在本公开的一些实施例中，基材为平面二维材料、曲面二维材料或三维结构；和/或基材为刚性材料或有机柔性材料。
在本公开的一些实施例中，基材为铝合金材料或钛合金材料的三维结构。
在本公开的一些实施例中，基材为二维柔性材料；在基材除减阻表面之外的另一表面上涂覆有粘合剂。
根据本公开的另一个方面，本公开还公开了一种仿生复合减阻表面的制备方法，包括：在减阻表面形成凸起结构，这些凸起结构在减阻表面形成沟槽织构；在沟槽织构中沟槽两侧凸起结构的上表面和/或侧面形成周期波纹结构；以及在周期波纹结构中波纹的表面覆盖低表面能涂层。
在本公开的一些实施例中，采用超短脉冲激光冷烧蚀的方式在减阻表 面加工凸起阵列，该凸起阵列在减阻表面形成交错沟槽织构。
在本公开的一些实施例中，利用超短脉冲激光光束在凸起阵列的上方辐照以在凸起结构的顶部获得周期波纹结构。
在本公开的一些实施例中，减阻表面为钛合金减阻表面；利用超短脉冲激光光束在凸起阵列的上方辐照以在凸起结构的顶部获得周期波纹结构的步骤中，辐照能量密度位于109mJ/cm 2和196.5mJ/cm 2之间。
在本公开的一些实施例中，在基材减阻表面覆盖低表面能涂层包括：准备低表面能材料的溶液；将低表面能材料的溶液转移至基材的减阻表面，待干燥后，低表面能材料覆盖于周期波纹结构中波纹的表面，形成低表面能涂层。
在本公开的一些实施例中，低表面能材料的溶液为氟硅烷的乙醇溶液，其中，溶质氟硅烷的重量百分比浓度介于0.5wt.％～6wt.％之间。
(三)有益效果
从以上技术方案可以看出，本公开仿生复合减阻表面及其制备方法，应用其的航行器具有下列有益效果：
(1)将多种减阻方式组合起来，协同作用，大大提升了减阻性能，可用于飞机、轮船、潜艇等外表面，进一步减小表面与流体之间的阻力，加速航行、节约能源；
(2)在提升减阻性能的同时，在减阻表面得到了超疏水性，由该超疏水性间接得到了防结冰性能、自清洗性能、抗空蚀性能和降噪性能：
①如在飞机机翼和尾翼蒙皮处制备超疏水性的减阻表面，能够防止结冰，解决结冰对飞机飞行引发的问题；
②用于海洋航行器底部，可以防止吸附的海洋污损生物降低航行器航速，降低耗油量，减少入坞次数和时间，减轻经济负担；
③用于海洋航行器螺旋桨，可以提高桨叶抗空蚀能力，提高推进效率，延长螺旋桨寿命；
④可减低航行带来的噪声，对于增强航行器作战能力有重要意义。
附图说明
图1为根据本公开实施例仿生复合减阻表面的基材上交错沟槽织构结构的示意图。
图2A和图2B分别为减阻表面上的连续沟槽织构和分段沟槽织构的示意图。
图3为根据本公开实施例仿生复合减阻表面的柱状凸起上周期波纹结构部分的放大图。
图4为制备本公开实施例仿生复合减阻表面的制备方法的流程图。
具体实施方式
在实现本公开的过程中，申请人逐渐认识到：单纯地依靠仿生鲨鱼沟槽结构，减阻效果的提升空间有限。针对此问题，申请人研究相关文献，发现航行体表面织构减阻除了仿生鲨鱼皮沟槽织构减阻之外，还有仿生超疏水表面织构减阻。申请人分析仿生鲨鱼皮沟槽减阻和仿生超疏水表面织构减阻机理之后，认为可以将两种减阻方式协同作用进行，申请人就此提出复合减阻方案，来进一步提高表面减阻效果。
为使本公开的目的、技术方案和优点更加清楚明白，以下结合具体实施例，并参照附图，对本公开进一步详细说明。
在本公开的一个示例性实施例中，提供了一种仿生复合减阻表面。本实施例仿生复合减阻表面包括：
基材，其具有减阻表面；
形成于减阻表面的凸起结构，该凸起结构在减阻表面形成沟槽织构；
形成于凸起结构的上表面和/或侧面的超疏水表面织构，该超疏水表面织构包括：形成于凸起结构的上表面和/或侧面的周期波纹结构以及涂覆于所述周期波纹结构波纹上的低表面能涂层。
本实施例中，将沟槽织构和和超疏水表面织构两种减阻方式有机结合起来，发挥各自优势，协同作用，大大提升了减阻性能。
以下对本实施例仿生复合减阻表面的各个组成部分进行详细说明。
本实施例中，基材可以是二维刚性材料，也可以是二维有机物柔性材料。本实施例中，考虑到交错沟槽织构和周期波纹结构采用激光加工方式制备，基材采用铝合金、钛合金及其它易于激光加工的材料。
此外，本领域技术人员应当理解，该基材并非一定是平面的二维材料，也可以是曲面二维材料或者三维结构。当本公开的技术方案应用至航行器上时，基材就是该航行器与流体接触的产生摩擦表面，例如船舶上应用本 公开的技术方案，基材就是船舶与水接触的表面。
在本公开优选的实施例中，在二维基材除减阻表面的另外一表面上，还涂覆有粘合剂，并粘贴有保护膜。在使用时，将保护膜撕离，就可以方便地将该仿生复合减阻表面粘贴到所需要的表面。
图1为根据本公开实施例仿生复合减阻表面的基材上交错沟槽织构的示意图。其中，(a)为交错沟槽织构的截面图；(b)为交错沟槽织构的俯视图。如图1中(a)和(b)所示，在基材的减阻表面上形成有柱状凸起所组成的阵列，该阵列形成减阻表面的交错沟槽织构。
可以看出，这些柱状凸起并非是简单排布，而是交错排布的，具体来说，所有的奇数排的排列结构相同，所有的偶数排的排列结构相同，奇数排与偶数排相错。
对于该柱状凸起，其横截面形状为矩形，凸起宽度a，同排相邻两柱状凸起之间的间隙为b，凸起宽度a和间隙b满足Cassie模型方程，θ e为本征接触角：
arccos[-1+a/(a+b)·(cosθ e+1)]≥150°
其中，本征接触角角度随基材的减阻表面材料的变化而变化，以钛合金为例，其本征接触角113°，凸起宽度a，间隙b的可取值范围为：5μm≤a≤30μm；120μm≤b≤500μm。
此外，对于柱状凸起，其高度h满足：h≥15μm；其长度l满足：100μm≤l≤200μm。
需要说明的是，除了横截面为矩形的柱状凸起之外，形成交错沟槽织构的凸起还可以是横截面为圆形的柱状凸起。甚至是锥形凸起、外锯齿状凸起或半圆形凸起，同样可以实现本公开。
本领域技术人员应当理解，除了由凸起阵列组成的交错沟槽阵列之外，其他形式的沟槽织构，例如，连续沟槽织构，如图2A所示；分段沟槽织构，如图2B所示。其中，在图2A和图2B中，黑色的部分为减阻表面上凸起的部分。
本实施例中，在交错沟槽织构中每个柱状凸起的表面形成有周期波纹结构，周期波纹结构的周期T大于100nm，小于1200nm。具体地，该周期波纹结构由激光制备，其周期为一个激光波长λ，例如：532nm、1064nm 等。周期波纹结构的深度与激光光束的能量有关，介于10nm～100nm之间。
图3为根据本公开实施例仿生复合减阻表面的柱状凸起上周期波纹结构部分的放大图。如图3中所示。周期波纹结构形成于柱状凸起的上表面。低表面能涂层的粒子附着在周期波纹结构中的波纹上。
需要说明的是，虽然图3中周期波纹结构仅是形成在柱状凸起的上表面，但在本公开的其他实施例中，该周期波纹结构同样还可以形成于凸起的侧面。因为采用激光光束制备周期波纹结构，柱状凸起的侧面并没有暴露在激光光束中，故在其上没有形成周期波纹结构。但是，对于其他类型的凸起，例如锯齿状凸起而言，其暴露在激光光束下的两个侧面上均会形成周期波纹结构。
此外，这些周期波纹结构中波纹上还覆盖着随机的纳米结构(表现为纳米孔、纳米絮、纳米突出等多种类型的纳米尺寸形貌)，即LIPSS(Laser Induced Periodical Surface Structure)。这种LIPSS对于疏水、减阻性能的提升能够起很大的作用。
在上述沟槽织构和周期波纹结构的基础上，在制备仿生超疏水表面时，还需要采用较低表面能物质修饰的化学方法来进一步降低固体工件的表面自由能才能增强疏水性能。此处的较低表面能指代的是表面能低于50mJ/m 2。
本实施例中，将低表面能涂层，例如：含有硅、氟等低表面能元素的材料覆盖在减阻表面来减小阻力。
经过实验证实，含氟材料及硅氧烷两种材料均具有较低的表面能，特别是含氟材料的表面能更低，并且C-F键越多，表面自由能也越小，所以-CF3基团比-CF2基团具有更低的表面能。究其原因，可能是因为-CF3基团的空间排列更紧密、相应单位面积中含氟量增大而导致氟原子间作用力较小，氟原子更容易外迁到表层使表面自由能降低。
十三氟辛基三乙氧基硅(F 13H 4Si(OC 2H 5) 3，简称氟硅烷)的分子结构上具有5个-CF2基团和1个-CF3基团，所以具有极低的表面能。本实施例中使用氟硅烷作为低表面能涂层涂覆在减阻表面。
本领域技术人员应当清楚，除了氟硅烷之外，还可以采用硅氧烷、自组装分子膜等低表面能涂层来覆盖基材的减阻表面。
以下介绍上述仿生复合减阻表面的制备方法。该制备方法中，在仿生鲨鱼皮的沟槽织构基础上再加工超疏水表面织构，沟槽织构和超疏水表面织构发挥各自减阻优势，达到减阻增强的目的。
图4为制备本公开实施例仿生复合减阻表面的制备方法的流程图。如图4所示，本实施例仿生复合减阻表面的制备方法包括：
步骤A，提供基材；
该基材可以是二维刚性材料，也可以是舰船本身的外侧面钢板或是柔性二维材料。只要其上具有需要减阻的表面即可。
步骤B，在基材的减阻表面加工凸起结构，这些凸起结构在减阻表面形成沟槽织构；
本实施例中，采用超短脉冲激光冷烧蚀的方式在基材的减阻表面加工柱状凸起阵列，该凸起阵列形成仿生鲨鱼交错沟槽织构。
激光加工为非接触式加工，因此无噪声、速度快，可实现各种复杂形状的高精度加工目的，且无需更换刀头，无通常意义上的刀具磨损，也对环境友好。
超短脉冲激光已经逐渐成为当前精细制造的主流加工方式。相较于其他表面处理方法，这种方法的核心优势在于适用于各种类型的材料，包括有机物、半导体、金属等，适用于其他加工方法无法实现的高精度、复杂微结构的加工。另一方面，超短脉冲激光在加工微米级结构的同时，具有同步诱导产生纳米结构的能力，可实现微纳复合结构的一次性制备。
本实施例中，通过超短脉冲激光可以进行材料表面的微结构加工与改性，还能还够克服传统长脉冲激光加工时热累积、传导带来的影响，获得精确的微纳结构制备效果。
步骤C，在沟槽织构中沟槽两侧凸起结构的上表面和/或侧面形成周期波纹结构；
本实施例中，利用超短脉冲激光光束在上述凸起阵列的上方直接辐照以在凸起结构的顶部获得周期波纹结构LIPSS(Laser Induced Periodical Surface Structure)。以钛合金为例，辐照能量密度应位于烧蚀阈值(109mJ/cm 2)和196.5mJ/cm 2之间，波纹的周期T近似等于所用激光波长λ。
激光制备LIPSS时，激光能量密度要大于烧灼阈值。对于金属材料， 一般认为上述LIPSS是由入射光和受激表面等离子体干涉形成的。这种干涉会导致能量的周期性沉积，从而导致金属表面周期性熔融与再凝固，最终形成表面周期性结构。该周期波纹结构的结构特征为周期条纹结构上覆盖着随机的纳米结构(表现为纳米孔、纳米絮、纳米突出等多种类型的纳米尺寸形貌)。
步骤D，在周期波纹结构中波纹的表面覆盖低表面能涂层。
本实施例中，该步骤D具体包括：
子步骤D1，准备1wt.％的氟硅烷的乙醇溶液；
具体地，本子步骤D1中，先把玻璃容器放置在电子称上，向其倒入一定量的无水乙醇；再按1wt.％的比例将氟硅烷缓慢地滴加到无水乙醇中，保证氟硅烷乙醇溶液浓度的精确性。将配置的溶液放置在磁力揽拌器上，在200r/min转速下揽拌3h，保证氟硅烷完全均匀地溶解于无水乙醇。
本领域技术人员应当清楚，也可以采购成品的氟硅烷的乙醇溶液，并且其重量百分比浓度介于0.5wt.％～6wt.％即可，并非局限于上述实施例中的1wt.％。
子步骤D2，将氟硅烷的乙醇溶液转移至基材的减阻表面，烘干，从而将氟硅烷材料覆盖于周期波纹结构中波纹的表面。
具体地，本子步骤D2中，在室温下把烘干的试件浸泡在配置好的1wt.％氟硅烷乙醇溶液中2h。最后，将其放置在温度为120℃的恒温烘箱中烘20min，烘干后，低表面能涂层的粒子附着在周期波纹结构中的波纹上，如图3所示。
本领域技术人员应当清楚，除了采取浸泡的方式之外，还可以采用例如涂覆、蒸发等方式将氟硅烷的乙醇溶液转移至基材的减阻表面，除了烘干之外，还可以采用晾干，红外光照射等方式将减阻表面的氟硅烷的乙醇溶液中的溶剂乙醇挥发，而在基材减阻表面留下氟硅烷。
至此，本公开实施例的仿生复合减阻表面及其制备方法介绍完毕。
需要说明的是，除了具有上述仿生复合高减阻结构的优点之外，在航行器的具体应用中，本公开还具有以下的有益效果：
(1)航行器的减阻表面具有超疏水性，从而具有仿结冰性能，如在飞机机翼和尾翼蒙皮处制备此表面，不仅具有减阻性能，并且还防止结冰， 解决结冰对飞机飞行引发的问题。
(2)航行器的减阻表面具有超疏水性，从而具有自清洗性能，可用于海洋航行器底部，防止吸附的海洋污损生物降低航行器航速，增加耗油量，增加入坞次数和时间，应用本发明的表面可以减轻经济负担。
(3)航行器的减阻表面具有超疏水性，从而具有抗空蚀性，可用于海洋航行器螺旋桨，提高桨叶抗空蚀能力，提高推进效率，延长螺旋桨寿命。
(4)航行器的减阻表面具有超疏水性，从而具有降噪性能，可用于航行器表面，减低航行带来的噪声，降低噪声对于增强航行器作战能力具有重要意义。
至此，已经结合附图对本公开各实施例进行了详细描述。
需要说明的是，在附图或说明书正文中，未绘示或描述的实现方式，均为所属技术领域中普通技术人员所知的形式，并未进行详细说明。此外，上述对各元件和方法的定义并不仅限于实施例中提到的各种具体结构、形状或方式，本领域普通技术人员可对其进行简单地更改或替换。
依据以上描述，本领域技术人员应当对本公开仿生复合减阻表面及其制备方法、应用其的航行器有了清楚的认识。
综上所述，本公开将多种减阻方法结合起来，发挥各自减阻优势，达到减阻增强、燃料节约的目的，可以用在汽车、飞机、船舶、火箭等各个领域，具有良好的推广应用价值。
还需要说明的是，实施例中提到的方向用语，例如“上”、“下”、“前”、“后”、“左”、“右”等，仅是参考附图的方向，并非用来限制本公开的保护范围。贯穿附图，相同的元素由相同或相近的附图标记来表示。在可能导致对本公开的理解造成混淆时，将省略常规结构或构造。
并且图中各部件的形状和尺寸不反映真实大小和比例，而仅示意本公开实施例的内容。另外，在权利要求中，不应将位于括号之间的任何参考符号构造成对权利要求的限制。
除非有所知名为相反之意，本说明书及所附权利要求中的数值参数是近似值，能够根据通过本公开的内容所得的所需特性改变。具体而言，所有使用于说明书及权利要求中表示组成的含量、反应条件等等的数字，应 理解为在所有情况中是受到「约」的用语所修饰。一般情况下，其表达的含义是指包含由特定数量在一些实施例中±10％的变化、在一些实施例中±5％的变化、在一些实施例中±1％的变化、在一些实施例中±0.5％的变化。
再者，单词“包含”不排除存在未列在权利要求中的元件或步骤。位于元件之前的单词“一”或“一个”不排除存在多个这样的元件。
此外，除非特别描述或必须依序发生的步骤，上述步骤的顺序并无限制于以上所列，且可根据所需设计而变化或重新安排。并且上述实施例可基于设计及可靠度的考虑，彼此混合搭配使用或与其他实施例混合搭配使用，即不同实施例中的技术特征可以自由组合形成更多的实施例。
类似地，应当理解，为了精简本公开并帮助理解各个公开方面中的一个或多个，在上面对本公开的示例性实施例的描述中，本公开的各个特征有时被一起分组到单个实施例、图、或者对其的描述中。然而，并不应将该公开的方法解释成反映如下意图：即所要求保护的本公开要求比在每个权利要求中所明确记载的特征更多的特征。更确切地说，如下面的权利要求书所反映的那样，公开方面在于少于前面公开的单个实施例的所有特征。因此，遵循具体实施方式的权利要求书由此明确地并入该具体实施方式，其中每个权利要求本身都作为本公开的单独实施例。
以上所述的具体实施例，对本公开的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上所述仅为本公开的具体实施例而已，并不用于限制本公开，凡在本公开的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本公开的保护范围之内。

Claims (18)

  1. 一种仿生复合减阻表面，包括：
    基材，其具有减阻表面；
    形成于所述减阻表面的凸起结构，该些凸起结构在沟槽表面形成沟槽织构；
    形成于凸起结构的上表面和/或侧面的超疏水表面织构，该超疏水表面织构包括：
    形成于凸起结构的上表面和/或侧面的周期波纹结构，以及
    涂覆于所述周期波纹结构波纹上的低表面能涂层。
  2. 根据权利要求1所述的仿生复合减阻表面，其中：
    所述沟槽织构中沟槽的宽度介于120μm至500μm之间；
    所述周期波纹结构中波纹的周期T大于100nm，小于1200nm。
  3. 根据权利要求2所述的仿生复合减阻表面，其中：
    所述沟槽织构为由凸起阵列形成的交错沟槽织构；
    所述凸起阵列中的凸起结构为以下凸起中的一种或多种：柱状凸起、锥形凸起、外锯齿状凸起或半圆形凸起。
  4. 根据权利要求3所述的仿生复合减阻表面，其中，所述凸起阵列中的凸起结构为柱状凸起，满足Cassie模型方程：
    arccos[-1+a/(a+b)·(cosθ e+1)]≥150°
    其中，a为柱状凸起的凸起宽度，b为同排相邻两柱状凸起之间的间隙，θ e为基材的减阻表面的材料的本征接触角。
  5. 根据权利要求4所述的仿生复合减阻表面，所述凸起阵列中的凸起结构为矩形横截面的柱状凸起；
    其中，Cassie模型方程中，5μm≤a≤30μm；120μm≤b≤500μm，100μm≤l≤200μm，h≥15μm，其中，l和h分别为柱状凸起的长度和高度。
  6. 根据权利要求2所述的仿生复合减阻表面，其中，所述周期波纹结构中波纹的深度介于10nm～100nm之间。
  7. 根据权利要求2所述的仿生复合减阻表面，其中，所述周期波纹结构中波纹上还覆盖有纳米结构，该纳米结构为以下结构中的一种或多种：纳米孔、纳米絮、纳米突出。
  8. 根据权利要求1所述的仿生复合减阻表面，其中，所述低表面能涂层的材料的表面能低于50mJ/m 2。
  9. 根据权利要求8所述的仿生复合减阻表面，其中，所述低表面能涂层为氟硅烷、硅氧烷或自组装分子膜。
  10. 根据权利要求1至9中任一项所述的仿生复合减阻表面，其中：
    所述基材为平面二维材料、曲面二维材料或三维结构；和/或
    所述基材为刚性材料或有机柔性材料。
  11. 根据权利要求10所述的仿生复合减阻表面，其中，所述基材为铝合金材料或钛合金材料的三维结构。
  12. 根据权利要求10所述的仿生复合减阻表面，其中，所述基材为二维柔性材料；在所述基材除减阻表面之外的另一表面上涂覆有粘合剂。
  13. 一种仿生复合减阻表面的制备方法，包括：
    在减阻表面形成凸起结构，这些凸起结构在减阻表面形成沟槽织构；
    在所述沟槽织构中沟槽两侧凸起结构的上表面和/或侧面形成周期波纹结构；以及
    在周期波纹结构中波纹的表面覆盖低表面能涂层。
  14. 根据权利要求13所述的制备方法，其中，采用超短脉冲激光冷 烧蚀的方式在减阻表面加工凸起阵列，该凸起阵列在减阻表面形成交错沟槽织构。
  15. 根据权利要求14所述的制备方法，其中，利用超短脉冲激光光束在所述凸起阵列的上方辐照以在凸起结构的顶部获得所述周期波纹结构。
  16. 根据权利要求15所述的制备方法，其中，所述减阻表面为钛合金减阻表面；
    所述利用超短脉冲激光光束在所述凸起阵列的上方辐照以在凸起结构的顶部获得所述周期波纹结构的步骤中，辐照能量密度位于109mJ/cm 2和196.5mJ/cm 2之间。
  17. 根据权利要求13所述的制备方法，所述在基材减阻表面覆盖低表面能涂层包括：
    准备低表面能材料的溶液；
    将低表面能材料的溶液转移至基材的减阻表面，待干燥后，低表面能材料覆盖于周期波纹结构中波纹的表面，形成低表面能涂层。
  18. 根据权利要求17所述的制备方法，其中，所述低表面能材料的溶液为氟硅烷的乙醇溶液，其中，溶质氟硅烷的重量百分比浓度介于0.5wt.％～6wt.％之间。
PCT/CN2018/074465 2018-01-29 2018-01-29 一种仿生复合减阻表面及其制备方法 WO2019144409A1 (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/CN2018/074465 WO2019144409A1 (zh) 2018-01-29 2018-01-29 一种仿生复合减阻表面及其制备方法

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2018/074465 WO2019144409A1 (zh) 2018-01-29 2018-01-29 一种仿生复合减阻表面及其制备方法

Publications (1)

Publication Number Publication Date
WO2019144409A1 true WO2019144409A1 (zh) 2019-08-01

Family

ID=67394498

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2018/074465 WO2019144409A1 (zh) 2018-01-29 2018-01-29 一种仿生复合减阻表面及其制备方法

Country Status (1)

Country Link
WO (1) WO2019144409A1 (zh)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102138009A (zh) * 2008-08-05 2011-07-27 美铝公司 具有摩擦力降低的织构化表面的金属薄板和板材及其制造方法
CN104439708A (zh) * 2014-11-18 2015-03-25 清华大学 一种超疏水高粘附金属表面及其制备方法
CN104947116A (zh) * 2015-05-28 2015-09-30 湖北工业大学 一种利用超短脉冲激光制备铝合金超疏水自清洁表面的方法
CN105504324A (zh) * 2015-12-23 2016-04-20 中国航空工业集团公司北京航空制造工程研究所 一种具有超疏水仿生表面的树脂基复合材料及其制备方法
CN107522161A (zh) * 2017-08-08 2017-12-29 清华大学 一种微纳米结构可控的铜基超疏水表面及其制备方法、应用

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102138009A (zh) * 2008-08-05 2011-07-27 美铝公司 具有摩擦力降低的织构化表面的金属薄板和板材及其制造方法
CN104439708A (zh) * 2014-11-18 2015-03-25 清华大学 一种超疏水高粘附金属表面及其制备方法
CN104947116A (zh) * 2015-05-28 2015-09-30 湖北工业大学 一种利用超短脉冲激光制备铝合金超疏水自清洁表面的方法
CN105504324A (zh) * 2015-12-23 2016-04-20 中国航空工业集团公司北京航空制造工程研究所 一种具有超疏水仿生表面的树脂基复合材料及其制备方法
CN107522161A (zh) * 2017-08-08 2017-12-29 清华大学 一种微纳米结构可控的铜基超疏水表面及其制备方法、应用

Similar Documents

Publication Publication Date Title
Liravi et al. A comprehensive review on recent advances in superhydrophobic surfaces and their applications for drag reduction
ES2585411T3 (es) Láminas y placas metálicas que tienen superficies con textura que reduce la fricción y métodos para fabricar las mismas
Yu et al. Bio-inspired drag reduction: From nature organisms to artificial functional surfaces
Xing et al. Anti-icing aluminum alloy surface with multi-level micro-nano textures constructed by picosecond laser
Fu et al. Marine drag reduction of shark skin inspired riblet surfaces
Yin et al. Femtosecond laser fabrication of shape-gradient platform: Underwater bubbles continuous self-driven and unidirectional transportation
Zhu et al. Bioinspired surfaces with special micro-structures and wettability for drag reduction: which surface design will be a better choice?
Luo et al. Boundary layer drag reduction research hypotheses derived from bio-inspired surface and recent advanced applications
Ahmadzadehtalatapeh et al. A review on the drag reduction methods of the ship hulls for improving the hydrodynamic performance
Li et al. Comparison of structures and hydrophobicity of femtosecond and nanosecond laser-etched surfaces on silicon
EP2535267B1 (en) System and method for reducing viscous force between a fluid and a surface
WO2006121909A2 (en) Friction drag-reducing surface
Kumar et al. Advances in drag-reduction methods related with boundary layer control–a review
West et al. Material selection and manufacturing of riblets for drag reduction: An updated review
Chen et al. Research progress and development trend of the drag reduction inspired by fish skin
WO2019144409A1 (zh) 一种仿生复合减阻表面及其制备方法
Ozen et al. Control of vortical structures on a flapping wing via a sinusoidal leading-edge
Chen et al. Open water characteristics of marine propeller with superhydrophobic surfaces
Guo et al. Femtosecond laser processed superhydrophobic surface
Mousavi et al. The potential for anti-icing wing and aircraft applications of mixed-wettability surfaces-A comprehensive review
Wang et al. A review on ultrafast laser enabled excellent superhydrophobic anti-icing performances
Kumar et al. A review on methods used to reduce drag of the ship hulls to improve hydrodynamic characteristics
Fürbacher et al. Icing Wind Tunnel and Erosion Field Tests of Superhydrophobic Surfaces Caused by Femtosecond Laser Processing
Li et al. Superhydrophobic biomimetic microstructures prepared by laser-ablation for drag reduction
Ragutkin et al. Creation of Hydrophobic Functional Surfaces of Structural Materials on the Basis of Laser Ablation (Overview)

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18903022

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18903022

Country of ref document: EP

Kind code of ref document: A1