Composite material as well as preparation method and application thereof

Abstract

The invention relates to a composite material and a preparation method and application thereof, and the composite material comprises a base material, and an anodic oxide film layer, a basic plating layer, a functional plating layer and a color plating layer which are sequentially arranged on one surface of the base material from inside to outside, the functional plating layers comprise a plurality of first functional plating layers and a plurality of second functional plating layers which are alternately arranged; metal elements in the first functional plating layer are different from metal elements in the second functional plating layer, or the first functional plating layer contains metal elements and the second functional plating layer does not contain metal elements. According to the composite material provided by the invention, the plurality of first functional plating layers and the plurality of second functional plating layers are alternately arranged, so that the longitudinal resistance values of the functional plating layers are increased, the corrosion of a primary battery during a corrosion test is weakened, meanwhile, the compactness of the functional plating layers is also improved, the defects of a film layer are reduced, and the service life of the film layer is prolonged. And the wear resistance of the composite material is enhanced.

Description

Technical Field

[0001] The present invention belongs to the field of film coating, and in particular relates to a composite material and a preparation method and application thereof. Background Art

[0002] With the development of smart electronic products such as mobile phones and other fields, the demand for metal products such as stainless steel and aluminum alloys continues to grow. Stainless steel has good chemical stability and can be directly processed by PVD (Physical Vapor Deposition), while aluminum alloy has poor corrosion resistance and generally requires a layer of aluminum oxide film to be formed on the surface of the aluminum substrate.

[0003] Currently, substrates such as aluminum alloys are typically coated with three layers. For example, CN203855635U discloses a vacuum coating method for aluminum. The surface of the aluminum body is coated with three layers, sequentially from the inside out: the first layer is aluminum oxide, the second layer is a titanium-chromium film composed of metallic chromium and titanium, and the third layer is a titanium nitride or titanium carbide film. This coating method utilizes ultra-hard aluminum oxide as the base layer of the pure aluminum product. The titanium-chromium film, titanium nitride, or titanium carbide film are then vacuum-coated, imparting wear resistance, corrosion resistance, and a variety of decorative colors to the coated substrate. However, this film structure has the following defects: First, due to the large difference in thermal expansion coefficient between the coating and the metal hardness, the aluminum oxide film prepared on the metal surface by vacuum coating results in poor adhesion of the film; Second, the second coating is a single layer of chromium and titanium metal film. Due to the single structure of the coating, the corrosion liquid may penetrate into the substrate during the corrosion test, and the film metal has a low resistivity and is easily connected to the aluminum substrate through the corrosion liquid, causing galvanic corrosion, which in turn leads to poor overall corrosion resistance of the coated substrate. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems existing in the above-mentioned prior art and provide a composite material with good wear resistance and corrosion resistance.

[0005] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a composite material, which includes a substrate and an anodized film layer, a basic coating layer, a functional coating layer and a color coating layer arranged on a surface of the substrate from the inside to the outside, wherein the functional coating layer includes a plurality of first functional coating layers and a plurality of second functional coating layers arranged alternately; the metal elements in the first functional coating layer are different from the metal elements in the second functional coating layer, or the first functional coating layer contains metal elements while the second functional coating layer does not contain metal elements; the metal elements are selected from one or more of Group IVB metals, Group VB metals, Group VIB metals and Group IVA metals.

[0006] Optionally, the number of layers of the first functional coating layers and the number of layers of the second functional coating layers are each independently 2-10 layers.

[0007] Optionally, the number of layers of the first functional coating layers and the number of layers of the second functional coating layers are each independently 3-8 layers.

[0008] Optionally, the thickness of the first functional coating layer is 100-300 nm; and / or the thickness of the second functional coating layer is 50-150 nm.

[0009] Optionally, the first functional coating includes a first element and a second element, the first element is selected from at least one of Cr, Ti, Zr, W, Nb, Mo, Ta and Ge, and the second element is selected from C and / or N.

[0010] Optionally, the first element in the first functional coating layer is partially or completely the same as the element in the basic coating layer.

[0011] Optionally, the first functional coating further contains O element.

[0012] Optionally, the second functional coating layer is selected from one or more of an aluminum oxide layer, a silicon oxide layer and a silicon nitride layer.

[0013] Optionally, the anodized film layer has a porous structure; and / or the pores in the anodized film layer have a pore size of 15-35 nm; and / or the porosity of the anodized film layer is 10-20%; and / or the thickness of the anodized film layer is 5-15 μm.

[0014] Optionally, the substrate is an aluminum alloy; and the element of the basic coating is selected from at least one of Cr, Ti, Zr, W, Nb, Mo, Ta and Ge.

[0015] Optionally, the color coating includes a third element and a selective fourth element, the third element is selected from at least one of Cr, Ti, W and Si, and the fourth element includes C and / or N.

[0016] Optionally, the thickness of the base coating is 100-300 nm; and / or the thickness of the color coating is 300-800 nm.

[0017] Optionally, the wear resistance of the composite material meets the following requirements: in a vibration wear test, the maximum vibration wear time for a wear test result below level 1 is more than 4 hours; and / or the corrosion resistance of the composite material meets at least one of the following requirements: in a water boiling test, the maximum water boiling treatment time for a cross-cut test result below level 1 is more than 1.5 hours; in a neutral salt spray test, the maximum neutral salt spray treatment time for a cross-cut test result below level 1 is more than 48 hours; in an artificial sweat test, the maximum artificial sweat treatment time for a cross-cut test result below level 1 is more than 96 hours.

[0018] The second aspect of the present invention provides a method for preparing a composite material, which includes: performing anodizing on a substrate to obtain a substrate with an anodized film layer attached; performing physical vapor deposition on the substrate with the anodized film layer attached; the physical vapor deposition includes the following steps: performing a first magnetron sputtering on the substrate with the anodized film layer attached to deposit a basic coating on the surface of the anodized film layer; performing a second magnetron sputtering and a third magnetron sputtering alternately on the basic coating multiple times to deposit a functional coating on the surface of the basic coating; the functional coating includes a plurality of first functional coatings and a plurality of second functional coatings arranged alternately; performing a fourth magnetron sputtering on the surface of the functional coating to deposit a color coating on the surface of the functional coating; wherein the metal element in the first functional coating is different from the metal element in the second functional coating, or the first functional coating contains a metal element while the second functional coating does not contain a metal element; the metal element is selected from one or more of Group IVB metals, Group VB metals, Group VIB metals, and Group IVA metals.

[0019] Optionally, the anodizing comprises the following steps: performing an anodizing treatment in a sulfuric acid solution using graphite as a cathode and the substrate as an anode to obtain a substrate with the first anodized film layer attached thereto.

[0020] Optionally, the anodizing treatment time is 30-60 min; the voltage is 8-15 V; and the sulfuric acid concentration is 100-200 g / L.

[0021] Optionally, the anodizing further comprises: placing the substrate with the first anodized film layer attached thereto in a phosphoric acid solution for pore expansion treatment to obtain a substrate with a second anodized film layer formed thereon.

[0022] Optionally, the concentration of the phosphoric acid solution is 3-10 wt %; and the time for the pore expansion treatment is 2-10 min.

[0023] Optionally, the number of the plurality of second magnetron sputtering operations and the number of the plurality of third magnetron sputtering operations are each independently 2-10 times.

[0024] Optionally, the number of the plurality of second magnetron sputtering operations and the number of the plurality of third magnetron sputtering operations are each independently 3-8 times.

[0025] Optionally, the conditions for the first magnetron sputtering include: the target material is at least one of Cr, Ti, Zr, W, Nb, Mo, Ta and Ge; and / or the conditions for the second magnetron sputtering include: the target material is at least one of Cr, Ti, Zr, W, Nb, Mo, Ta and Ge, and the reaction gas is nitrogen or acetylene; and / or the conditions for the third magnetron sputtering include: the target material is Al or Si; the reaction gas is oxygen or nitrogen; and / or the conditions for the fourth magnetron sputtering include: the target material is at least one of Cr, Ti, W and Si; the reaction gas is nitrogen and / or acetylene.

[0026] Optionally, the metal elements of the first functional coating layer are partially the same as or completely the same as the metal elements of the basic coating layer.

[0027] A third aspect of the present invention provides a shell, which comprises the composite material provided by the first aspect of the present invention.

[0028] A fourth aspect of the present invention provides an electronic device, which includes the housing provided by the third aspect of the present invention.

[0029] Through the above technical solution, the composite material of the present invention increases the longitudinal resistance of the functional coating layer by alternating multiple first and second functional coating layers, reducing the occurrence of galvanic corrosion during corrosion testing, while not affecting the original performance of the film layer. The alternating first and second functional coating layers improve the density of the functional coating layer, reduce film defects, and enhance the corrosion resistance of the composite material. At the same time, by first forming a self-grown anodic oxide film on the surface of the substrate, the difference in thermal expansion coefficient between the anodic oxide film layer and the substrate is small, which strengthens the bonding strength of the entire film layer to the substrate, allowing for better coordination with the base coating layer, functional coating layer, and color coating layer, thereby improving the wear resistance of the composite material.

[0030] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0032] Figure 1 It is a cross-sectional view of a local structure of a composite material according to an embodiment of the present invention.

[0033] Description of reference numerals:

[0034] 1. Substrate; 2. Anodic oxide film; 3. Basic coating; 4. Functional coating; 41. First functional coating; 42. Second functional coating; 5. Color coating. DETAILED DESCRIPTION

[0035] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0036] The first aspect of the present invention provides a composite material, which includes a substrate and an anodized film layer, a base coating, a functional coating and a color coating arranged on a surface of the substrate from the inside to the outside; the metal element in the first functional coating is different from the metal element in the second functional coating, or the first functional coating contains a metal element while the second functional coating does not contain a metal element; the metal element is selected from one or more of Group IVB metals, Group VB metals, Group VIB metals and Group IVA metals.

[0037] In the present invention, by alternating the first and second functional coatings, the longitudinal resistance of the functional coating is increased, reducing galvanic corrosion during corrosion testing without affecting the original performance of the film. The alternating first and second functional coatings improve the density of the functional coating, reduce film defects, and enhance the corrosion resistance of the composite material. Furthermore, by pre-forming a self-grown anodic oxide film on the substrate surface, the difference in thermal expansion coefficient between the anodic oxide film and the substrate is minimized, enhancing the overall bonding strength between the film and the substrate, allowing for better coordination between the base coating, functional coating, and color coating, and improving the composite material's wear resistance.

[0038] See also Figure 1 , Figure 1 This is a cross-sectional view of the local structure of a composite material according to an embodiment of the present invention. The composite material includes a substrate 1 and an anodized film layer 2 formed on the surface of the substrate. The surface of the anodized film layer is sequentially formed with a basic coating layer 3, a functional coating layer 4 and a color coating layer 5 by magnetron sputtering, wherein the functional coating layer 4 includes 2-10 layers of a first functional coating layer 41 and a second functional coating layer 42 alternately arranged.

[0039] In some embodiments of the present invention, the number of layers of the plurality of first functional coating layers and the number of layers of the plurality of second functional coating layers are independently 2-10 layers. In the present invention, "alternating arrangement" can be understood as the first functional coating layer 41 and the second functional coating layer 42 being stacked in sequence. For example, the first functional coating layer 41 is stacked on the base coating layer 3, and the second functional coating layer 42 is stacked on the first functional coating layer 41. In this way, the number of layers of the first functional coating layer 41 and the second functional coating layer 42 are each one. On the basis of the above, a first functional coating layer 41 is stacked on the second functional coating layer 42, and a second functional coating layer 42 is stacked on the first functional coating layer 41. In this way, the number of layers of the first functional coating layer 41 and the second functional coating layer 42 are each two. Similarly, 2-10 layers of the first functional coating layer 41 and the second functional coating layer 42 can be set according to the desired effect.

[0040] Specifically, the number of layers of the first functional coating layer and the second functional coating layer can be 2 layers, 3 layers, 4 layers, 5 layers, 6 layers, 7 layers, 8 layers, 9 layers or 10 layers. In this way, the structure of the functional coating layer can be simplified. By alternately stacking the first functional coating layer and the second functional coating layer with the above number of layers, the density of the functional coating layer is improved, the defects of the film layer are reduced, and the corrosion resistance of the film layer is improved. In some preferred embodiments, the number of layers of the first functional coating layer and the second functional coating layer is independently 3-8 layers. By alternately stacking the first functional coating layer and the second functional coating layer 3-8 times, the longitudinal resistance value of the film layer itself can be increased, the corrosion resistance of the composite material can be improved, and the overall thickness of the composite material can be effectively reduced.

[0041] In some embodiments of the present invention, the substrate 1 may be an aluminum alloy, and accordingly, the anodized film layer 2 is an aluminum oxide film layer grown on the surface of the aluminum alloy by an anodizing method.

[0042] In some embodiments of the present invention, the anodic oxide film layer 2 has a porous structure. Specifically, the porosity of the anodic oxide film layer can be 10-20%, the pore diameter of the anodic oxide film layer can be 15-35 nm, and the thickness of the anodic oxide film layer can be 5-15 μm. The anodic oxide film layer having such a structure has a good bonding effect with the substrate and the base coating, has excellent wear resistance, and does not affect the appearance and metallic texture of the composite material.

[0043] In some embodiments of the present invention, the element of the base coating 3 is selected from at least one of Cr, Ti, Zr, W, Nb, Mo, Ta and Ge. Preferably, the base coating is selected from at least one of Cr, Ti, W and Nb. For example, the base coating 3 may be a Cr layer, a Ti layer, a W layer, a Nb layer or a CrTi layer. The base coating 3 is placed between the anodic oxide film layer 2 and the functional coating 4 to increase the adhesion between the functional coating 4 and the anodic oxide film layer 2. The base coating 3 made of these materials can effectively prevent the film layer of the composite material from falling off from the surface of the substrate, thereby improving the wear resistance of the composite material.

[0044] In some embodiments of the present invention, specifically, the thickness of the basic coating 3 is preferably 100-300 nm. Specifically, the thickness of the basic coating can be 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm or any value within the aforementioned range. The thickness of the basic coating 3 is moderate, which is not only conducive to enhancing the adhesion between the functional coating 4 and the anodized film layer 2, but also conducive to reducing the overall thickness of the composite material.

[0045] In some embodiments of the present invention, the first functional coating 41 includes a first element and a second element, wherein the first element is selected from at least one of Cr, Ti, Zr, W, Nb, Mo, Ta, and Ge, and the second element is selected from C and / or N. The first element is selected from at least one of Cr, Ti, Zr, W, Nb, Mo, Ta, and Ge, which can improve the wear resistance and corrosion resistance of the film. Specifically, the first element is selected from at least one of Cr, Ti, W, and Nb. For example, the first functional coating 41 can be a CrC layer, a CrN layer, a TiC layer, a TiN layer, a CrTiWC layer, or a CrTiWN layer. The first functional coating has good adhesion to the base coating and can transition to the color coating, thereby making the surface of the composite material present a uniform color.

[0046] In some embodiments of the present invention, the thickness of the first functional coating 41 is preferably 100-300 nm. Specifically, the thickness of the first functional coating 41 can be 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, or any value within the aforementioned range. In this way, while achieving the corrosion resistance and wear resistance of the composite material, the first functional coating not only has good adhesion to the base coating, but also combines with the color coating to produce a good visual effect, and is also conducive to controlling the overall thickness of the composite material.

[0047] In the present invention, the first element and the second element of each of the cyclically alternately stacked first functional coating layers 41 may be the same or different. Preferably, in order to reduce the difficulty of the process, the first element and the second element of each of the first functional coating layers 41 are the same.

[0048] In some embodiments, the first element is the same as the element in the base coating layer to save costs and reduce process difficulty. Preferably, the first element in the first functional coating layer 41 is partially or completely the same as the element in the base coating layer 3. That is, the metal element in the first functional coating layer is partially or completely the same as the element in the base coating layer, thereby increasing the bonding strength between the first functional coating layer and the base coating layer.

[0049] In some embodiments of the present invention, the first functional coating further contains the element O. Nitrogen oxides have a higher electrical resistance and better bonding with metals or metal compounds, further enhancing the corrosion resistance of the film while maintaining bonding strength. By alternating the layers of nitrogen oxides and the first functional coating, the corrosion resistance of the composite material is further enhanced while maintaining bonding strength.

[0050] In some embodiments of the present invention, the second functional coating 42 is selected from one or more of an aluminum oxide layer, a silicon oxide layer, and a silicon nitride layer. These materials can meet the hardness requirements of the functional coating, and the precursors of these materials are easily obtained. The aluminum oxide layer has the properties of high Vickers hardness and high resistance. By using aluminum oxide layers and silicon oxide layers and silicon nitride layers with similar properties to alternately stack the first functional coating layer, the longitudinal resistance value of the composite film layer is further increased. Among them, the elements of each second functional coating layer that is alternately stacked in a cyclic manner can be the same or different. Preferably, in order to reduce the difficulty of the process, the elements of each second functional coating layer are the same.

[0051] In some embodiments of the present invention, the thickness of the second functional coating 42 is preferably 50-150 nm. Specifically, the thickness of the second functional coating 42 can be 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, or any value within the aforementioned range. The second functional coating 42 has a high Vickers hardness. These second functional coatings have high electrical resistance, which helps reduce the overall thickness of the composite material while improving the corrosion resistance and wear resistance of the composite material.

[0052] In some embodiments of the present invention, the color coating 5 includes a third element and a selective fourth element, the third element is selected from at least one of Cr, Ti, W and Si, and the fourth element includes C and / or N. The third element in the color coating is also beneficial to enhance the adhesion between the film layers, and the combination of the third element and the fourth element is beneficial to make the composite material present a uniform color. Specifically, the color coating 5 can be a Cr layer, a Ti layer, a W layer, a Si layer, a CrTi layer, a TiN layer, a TiCN layer, a CrCN layer or a CrSiCN layer. The color coating is used to adjust the color of the composite material. According to the required color effect, by adjusting the physical vapor deposition process or the thickness of the color coating, the color of the color coating can be made richer, and the color coating and the aforementioned basic coating and functional coating are combined to make the composite material present a more uniform color.

[0053] In some embodiments of the present invention, the thickness of the color coating is preferably 300-800 nm. Specifically, the thickness of the color coating can be 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, or any value within the aforementioned range. This ensures that the composite material exhibits a uniform metallic luster while ensuring wear resistance, corrosion resistance, and scratch resistance, and can also reduce the material cost of the color coating.

[0054] In some embodiments, the basic coating layer, the functional coating layer, and the color coating layer work together to not only make the surface of the substrate present a uniform color, but also have good wear resistance and corrosion resistance.

[0055] In the present invention, the wear resistance of the composite material meets the following requirements: in a vibration wear test, the maximum vibration wear time for a wear test result below level 1 is more than 4 hours; and / or the corrosion resistance of the composite material meets at least one of the following requirements: in a water boiling test, the maximum water boiling treatment time for a cross-cut test result below level 1 is more than 1.5 hours; in a neutral salt spray test, the maximum neutral salt spray treatment time for a cross-cut test result below level 1 is more than 48 hours; in an artificial sweat test, the maximum artificial sweat treatment time for a cross-cut test result below level 1 is more than 96 hours.

[0056] The operation of vibration wear is as follows: put the sample into the Rosler vibration wear tester, in which abrasive, water and detergent are also placed; the abrasive includes 3 parts of RKF 10K (yellow cone) and 1 part of RKK15P (green pyramid), a total of about 15L, the amount of water is 1L, and the amount of detergent is 200mL; add 0.5L of pure water every half an hour during the operation; take photos and observe after every half an hour. The grade of the wear test results is determined according to the following standards: Grade 0: There is no obvious wear and bruises on the large surface, corners and edges of the sample, and the color is as clear as before; Grade 1: There is no wear on the large surface of the sample, and only slight bruises and wear can be seen on the composite film layer at the corners and ridges, but the wear does not expose the substrate, and the area of ​​a single bruise is less than 1mm. 2 Level 2: A small amount of point wear occurs on the large surface of the specimen, and the largest single wear area is less than 1mm 2 , or the edges and corners are worn through (leaking out the base material), and the maximum wear line width is less than 1mm.

[0057] Among them, 100℃ boiling water treatment refers to placing the sample in 100℃ pure water and heating it in water; neutral salt spray treatment refers to spraying salt spray (NaCl solution concentration of 5wt% and pH value of 6.8) for 24 hours under the conditions of 35±2℃ and humidity>85%; artificial sweat treatment refers to coating the material containing artificial sweat for 48 hours under the conditions of 45℃ and relative humidity of 95%. The artificial sweat includes: 1000 parts by weight of water, 19.5 parts by weight of 85% lactic acid, 5±0.01 parts by weight of urea, 20±0.01 parts by weight of sodium chloride, 17.50±0.01 parts by weight of NH4Cl, 2.62 parts by weight of anhydrous acetic acid and an appropriate amount of sodium hydroxide powder. The pH value of the artificial sweat is 4.7.

[0058] The cross-cut test is conducted in accordance with GB / T 9286-2021. Specifically, a grid is drawn on the composite material sample at a 1mm spacing, forming 10×10 continuous 1mm×1mm square grids. Each grid line extends to the substrate, and the cross-cut area is clean. A section of tape approximately 75mm long is applied to the cross-cut area (pressure-sensitive adhesive tape), with the tape extending at least 20mm beyond the grid line to ensure effective contact between the tape and the sample coating. After 3 minutes of rest, the tape is held at the free end, held at a 60° angle to the sample as much as possible, and removed smoothly within 1.0s. The film is inspected for any peeling and the results are evaluated. The results are graded as follows: Grade 0: Completely smooth cut edges, no peeling at the cut edges; Grade 1: Small peeling at the cut intersections, with the actual damage area within the cross-cut area not exceeding 5%; Grade 2: Peeling at the cut edges and intersections, with the actual damage area within the cross-cut area ranging from 5% to 15%.

[0059] The second aspect of the present invention provides a method for preparing a composite material, which includes: performing anodizing on a substrate to obtain a substrate with an anodized film layer attached; performing physical vapor deposition on the substrate with the anodized film layer attached; the physical vapor deposition includes the following steps: performing a first magnetron sputtering on the substrate with the anodized film layer attached to deposit a basic coating on the surface of the anodized film layer; performing a second magnetron sputtering and a third magnetron sputtering alternately on the basic coating multiple times to deposit a functional coating on the surface of the basic coating; the functional coating includes a plurality of first functional coatings and a plurality of second functional coatings arranged alternately; performing a fourth magnetron sputtering on the surface of the functional coating to deposit a color coating on the surface of the functional coating; wherein the metal element in the first functional coating is different from the metal element in the second functional coating, or the first functional coating contains a metal element while the second functional coating does not contain a metal element; the metal element is selected from one or more of Group IVB metals, Group VB metals, Group VIB metals, and Group IVA metals.

[0060] To improve the corrosion resistance of the composite material and to reduce costs, the present invention employs magnetron sputtering technology to sequentially form a base coating, a functional coating, and a color coating on the surface of the oxide film. Magnetron sputtering technology offers a high deposition rate and low processing costs, and the resulting PVD film layer bonds well with the anodic oxide film layer. In the present invention, by performing multiple alternating second and third magnetron sputtering processes, alternating first and second functional coating layers can be formed on the base coating formed by the first magnetron sputtering process. This increases the longitudinal resistance of the film layer itself, reduces film defects, and improves the corrosion resistance of the composite material.

[0061] In some embodiments of the present invention, the anodizing comprises the following steps: performing an anodizing treatment in a sulfuric acid solution using graphite as a cathode and the substrate as an anode to obtain a substrate having the first anodized film layer attached thereto.

[0062] In some embodiments of the present invention, the anodic oxidation treatment time is 30-60 min; the voltage is 8-15 V; and the sulfuric acid concentration is 100-200 g / L.

[0063] The anodizing further comprises: placing the substrate with the first anodized film layer attached thereto in a phosphoric acid solution for pore expansion treatment to obtain a substrate with a second anodized film layer formed thereon.

[0064] In some embodiments of the present invention, the concentration of the phosphoric acid solution is 3-10 wt% and the pore expansion treatment time is 2-10 minutes. By performing the aforementioned anodizing treatment on the substrate surface, an anodized film having a thermal expansion coefficient slightly different from that of the substrate is formed on the substrate surface. This can enhance the overall bonding strength between the substrate and the composite film layer thereon, thereby improving the wear resistance of the composite material.

[0065] In some embodiments of the present invention, the number of the plurality of second magnetron sputterings and the number of the plurality of third magnetron sputterings are each independently 2 to 10. In some preferred embodiments of the present invention, the number of the plurality of second magnetron sputterings and the number of the plurality of third magnetron sputterings are each independently 3 to 8.

[0066] In some embodiments of the present invention, the conditions for the first magnetron sputtering include: the target material is at least one of Cr, Ti, Zr, W, Nb, Mo, Ta, and Ge. Forming the base coating layer on the anodic oxide film by magnetron sputtering increases the bonding strength between the base coating layer and the anodic oxide film, further strengthening the bonding strength between the substrate and the PVD film layer.

[0067] In some embodiments of the present invention, the conditions for the second magnetron sputtering include: the target material is at least one of Cr, Ti, Zr, W, Nb, Mo, Ta and Ge, and the reaction gas is nitrogen or acetylene.

[0068] In some embodiments of the present invention, the metal elements of the first functional coating layer are partially identical or completely identical to the metal elements of the basic coating layer, so that the bonding strength between the first functional coating layer and the basic coating layer is increased.

[0069] In some embodiments of the present invention, the conditions for the third magnetron sputtering process include: a target material of Al or Si, and a reactive gas of oxygen or nitrogen. Using magnetron sputtering to form the alternating first and second functional coating layers results in dense and uniform films, further improving the corrosion and wear resistance of the functional coating layers.

[0070] In some embodiments of the present invention, the fourth magnetron sputtering process is performed under the following conditions: the target material is at least one of Cr, Ti, W, and Si; and the reactive gas is nitrogen and / or acetylene. During the fourth magnetron sputtering process, if the color coating does not contain C and / or N, no reactive gas is introduced. The color coating formed on the functional coating using the PVD process exhibits high hardness and excellent wear, corrosion, and scratch resistance.

[0071] In one embodiment of the present invention, the method for preparing the composite material comprises the following steps:

[0072] (1) placing an aluminum alloy substrate in 100-200 g / L sulfuric acid and oxidizing it at 8-15 V for 30-60 min, washing it with water, and then placing it in a 3-10 wt% phosphoric acid solution for pore expansion treatment for 2-10 min. The expanded aluminum alloy substrate is baked at 80-120° C. for 30-40 min. Preferably, the aluminum oxide film layer has a thickness of 5-15 μm, a micropore diameter of 15-35 nm, and a porosity of 10-20%.

[0073] (2) placing the oxidized substrate in a vacuum furnace and evacuating the vacuum, heating it to 80-180° C., filling the machine with argon gas, turning on the ion source, and performing ion cleaning on the surface of the aluminum alloy substrate and the target;

[0074] (3) placing the ion-cleaned substrate in a vacuum furnace and evacuating the vacuum, heating it to 60-90° C., filling the machine with argon gas, and simultaneously turning on a medium-frequency sputtering power source for at least one target material selected from Cr, Ti, Zr, W, Nb, Mo, Ta, and Ge; depositing a base coating on the surface of the aluminum oxide film layer of the aluminum alloy substrate, preferably, the base coating has a thickness of 100-300 nm;

[0075] (4) introducing argon gas into the vacuum furnace, turning on the medium frequency sputtering power supply of at least one target material selected from Cr, Ti, Zr, W, Nb, Mo, Ta, and Ge, introducing nitrogen or acetylene as a reaction gas, and depositing a first functional coating on the surface of the base coating. Preferably, the thickness of the first functional coating is 100-300 nm;

[0076] (5) introducing argon gas into the vacuum furnace, turning on the sputtering power supply of one of the Al and Si targets, introducing oxygen or nitrogen gas, and depositing a second functional coating layer on the surface of the first functional coating layer. Preferably, the thickness of the second functional coating layer is 50-150 nm;

[0077] (6) Repeat steps (4) and (5) 2-10 times in sequence to alternately stack the first functional coating and the second functional coating, then introduce argon gas into the vacuum furnace, turn on the sputtering power of at least one target material among Cr, Ti, W and Si, and selectively introduce reaction gas nitrogen and / or acetylene to deposit a color coating on the surface of the second functional coating. Preferably, the thickness of the color coating is 300-800 nm.

[0078] In some embodiments of the present invention, the substrate may be pretreated before anodizing to remove oil stains on the surface of the substrate, such as by sequentially performing water washing, degreasing, and neutralization treatments.

[0079] The composite material of the present invention has a simple preparation process and high repeatability, and the formed composite film layer has good stability, and can be widely used in modern intelligent terminal shell structure products.

[0080] The third aspect of the present invention provides a housing, which comprises the composite material provided by the first aspect of the present invention. Specifically, part or all of the housing can be made of the aforementioned composite material.

[0081] The present invention further provides an electronic device comprising the housing provided in the third aspect of the present invention. The housing of the present invention can be applied to electronic devices. For example, in some embodiments of the present invention, the electronic device can be a mobile phone, a laptop computer, a tablet computer, a watch, a camera, a monitoring device, an AR device, or a VR device. The housing can be a back cover, a middle frame, or other decorative structure of the electronic device.

[0082] The present invention is further described in detail below by way of examples, but the present invention is not limited to the following examples.

[0083] Example 1

[0084] The composite material of this embodiment includes an aluminum alloy substrate and an anodized film layer, a basic coating layer, a functional coating layer and a color coating layer arranged on one surface of the substrate from the inside to the outside; the functional coating layer includes 5 layers of first functional coating layers (TiN layers) and 5 layers of second functional coating layers (Al2O3 layers) arranged alternately.

[0085] The method for preparing the composite material in this embodiment includes the following steps:

[0086] (1) The aluminum alloy substrate was washed, degreased, and neutralized in sequence, and then the cleaned aluminum alloy substrate was placed in 125g / L sulfuric acid and oxidized at 8V for 45 minutes, washed with water for 180 seconds, and then placed in a 6wt% phosphoric acid solution for pore expansion for 5 minutes. The expanded aluminum alloy substrate was baked at 80°C for 30 minutes; the aluminum oxide film obtained by anodization had a thickness of 10μm, a micropore diameter of 25nm, and a porosity of 10%;

[0087] (2) placing the oxidized substrate in a vacuum coating machine and performing ion cleaning on the substrate and target surfaces;

[0088] (3) introducing argon gas into the vacuum furnace, turning on the medium-frequency sputtering power supply of the Ti target, and depositing a base coating (Ti layer) on the surface of the aluminum oxide film layer of the aluminum alloy substrate. The thickness of the Ti layer is 150 nm;

[0089] (4) Argon gas was introduced into the vacuum furnace, the Ti target sputtering power supply was turned on, and then nitrogen gas was introduced as a reactive gas to deposit the first functional coating (TiN layer) on the surface of the base coating. The thickness of the TiN layer was 150 nm.

[0090] (5) introducing argon gas into the vacuum furnace, turning on the Al target sputtering power supply, and then introducing the reactive gas oxygen to deposit a second functional coating layer (Al2O3 layer) on the surface of the first functional coating layer. The thickness of the Al2O3 layer is 75 nm.

[0091] (6) Repeat steps (4) and (5) five times in sequence to alternately stack the first functional coating layer and the second functional coating layer; then, introduce argon gas into the vacuum furnace, turn on the sputtering power supply of the Cr target and the Ti target, and deposit a color coating layer (CrTi layer) on the surface of the second functional coating layer. The thickness of the CrTi layer is 550 nm.

[0092] Example 2

[0093] The method for preparing the composite material in this embodiment is the same as that in embodiment 1, except that: the basic coating layer is a Cr layer; the first functional coating layer is a CrN layer, and the thickness of the CrN layer is 120 nm.

[0094] Example 3

[0095] The method for preparing the composite material in this embodiment is the same as that in Example 1, except that the thickness of the anodic oxide film layer is 15 μm.

[0096] Example 4

[0097] The method for preparing the composite material in this embodiment is the same as that in Example 1, except that the functional coating includes two first functional coating layers of TiN and two second functional coating layers of Al2O3, which are alternately arranged, and the thickness of the first functional coating layer of TiN is 400 nm, and the thickness of the second functional coating layer of Al2O3 is 100 nm.

[0098] Example 5

[0099] The method for preparing the composite material in this embodiment is the same as that in Example 1, except that the functional coating includes three first functional coating layers of TiN and three second functional coating layers of Al2O3, which are alternately arranged; and the thickness of the first functional coating layer of TiN is 300 nm, and the thickness of the second functional coating layer of Al2O3 is 150 nm.

[0100] Example 6

[0101] The method for preparing the composite material in this embodiment is the same as that in Example 1, except that the functional coating includes 8 layers of first functional coating TiN layers and 8 layers of second functional coating Al2O3 layers arranged alternately, and the thickness of the first functional coating CrN layer is 150nm, and the thickness of the second functional coating Al2O3 layer is 75nm.

[0102] Example 7

[0103] The method for preparing the composite material in this embodiment is the same as that in Example 1, except that the functional coating includes 10 layers of the first functional coating TiN layer and 10 layers of the second functional coating Al2O3 layer arranged alternately, and the thickness of the first functional coating TiN layer is 100 nm, and the thickness of the second functional coating Al2O3 layer is 50 nm.

[0104] Example 8

[0105] The method for preparing the composite material in this embodiment is the same as that in Example 1, except that the functional coating includes four first functional coating layers of TiN and four second functional coating layers of Al2O3, which are alternately arranged, and the thickness of the first functional coating layer of TiN is 100 nm, and the thickness of the second functional coating layer of Al2O3 is 175 nm.

[0106] Example 9

[0107] The method for preparing the composite material in this embodiment is the same as that in embodiment 1, except that the second functional coating is a SiO2 layer; the color coating is a CrCN layer; the thickness of the second functional coating is 75 nm, and the thickness of the color coating is 550 nm.

[0108] Comparative Example 1

[0109] The method for preparing the composite material in this comparative example is the same as that in Example 1, except that the functional coating layer of the composite material is a TiN layer, and the thickness of the TiN layer is 1125 nm.

[0110] Comparative Example 2

[0111] The method for preparing the composite material in this comparative example is the same as that in Example 1, except that the functional coating layer of the composite material is a CrN layer, and the thickness of the CrN layer is 1200 nm.

[0112] Test Examples

[0113] The composite material samples prepared in Examples 1-9 and Comparative Examples 1-2 were subjected to performance tests, including a water boiling test, an artificial sweat test, a salt spray test, and a vibration wear test.

[0114] (1) Hundred-grid test

[0115] The 100-grid test of composite materials is carried out in accordance with GB / T 9286-2021. The 100-grid test is carried out at a temperature of 23±2°C and a relative humidity of 50±5%.

[0116] Test conditions: Grid the composite material sample with 1mm spacing, forming 10 x 10 continuous 1mm x 1mm squares. Each grid line extends to the substrate, and the grid area is clean. A section of tape approximately 75mm long is applied to the grid area (pressure-sensitive adhesive tape), with the tape extending at least 20mm beyond the grid line to ensure effective contact between the tape and the sample coating. Allow the tape to stand for 3 minutes. Holding the dangling end of the tape at a 60° angle to the sample, peel it away steadily within 0.5-1.0 seconds. Inspect the film for any signs of shedding and evaluate the results.

[0117] in:

[0118] Level 0: The cut edge is completely smooth and there is no peeling on the lattice edge.

[0119] Level 1: Small pieces peel off at the intersection of the cuts, and the actual damage in the grid area does not exceed 5%.

[0120] Level 2: There is peeling at the edges and intersections of the incision, covering an area of ​​5%-15%.

[0121] Level 3: The edges of the cuts are peeling off, large pieces are peeling off, and even some grids are peeling off. The peeling area is 15%-35%.

[0122] Level 4: Large pieces of the cut edge peel off, some grids peel off completely, and the peeled area is 35%-65%.

[0123] Level 5: Exceeds the previous level.

[0124] (2) Artificial sweat test

[0125] Test conditions: Before the test, check that the sample has no abnormal appearance and wipe the sample surface clean. Then, use a dust-free cloth soaked in artificial sweat to wipe the sample surface back and forth (wiping force is about 3-6N) for 2 minutes. After that, use a dust-free cloth to completely soak the sweat, half-wrap the sample (small parts are completely wrapped), and place it in a 45°C, 95% relative humidity incubator for 48 hours (single test cycle duration); after the test, take out the sample, wash it with water, and restore it to room temperature for 2 hours. Then check the appearance of the sample and perform the adhesion test in accordance with the above item (1). Record the maximum time for the salt spray test when the sample film layer has no abnormality and there is no obvious change in appearance (discoloration, rust, shedding, blistering, cracking, etc.), as well as the maximum artificial sweat treatment time when the 100-grid test reaches level 1 or below.

[0126] Preparation method of artificial sweat: 1L of water, 19.5g of 85% lactic acid, 5±0.01g of urea, 20±0.01g of sodium chloride, 17.50±0.01g of NH4Cl and 2.62g of anhydrous acetic acid, stir well, and add sodium hydroxide powder to make the solution pH reach 4.7.

[0127] (3) Neutral salt spray test

[0128] Test conditions: Before the test, check the appearance of the sample and wipe the surface of the sample clean. Then, place the composite material sample in the test machine at a 45-degree angle to the horizontal plane, with half of the sample facing up and half facing up. The conditions of a single test cycle include: temperature of 35±2℃, humidity of more than 85%, and continuous salt spraying of the composite material with a NaCl solution with a pH value of 6.8 and a concentration of 5wt% for 24 hours. Take a portion of the sample facing up and the sample facing up at room temperature for 2 hours, then check the appearance of the sample. The remaining samples are placed at 40℃ and 95% humidity for 168 hours, then restored to room temperature for 2 hours, and the test surface is checked. Record the maximum time for the salt spray test when the sample film layer has no abnormal appearance and no obvious changes in appearance (discoloration, rust, shedding, blistering, cracking, etc.). Refer to the above item (1) for the adhesion test. Record the maximum neutral salt spray treatment time for the sample to reach level 1 or below in the 100-grid test.

[0129] (4) Boiling test

[0130] Test conditions: Before testing, check the appearance of the sample and wipe the surface clean; heat pure water to 100°C and place the sample in a water bath, ensuring that the sample does not overlap, collide, or directly contact the heating rod; the water bath time is 180 minutes. After the test is completed, cool naturally to room temperature; inspect the appearance of the sample, and then perform the adhesion test in accordance with the above-mentioned item (1). Record the maximum time that the sample's appearance has no obvious corrosion, blistering, pitting, cracking, deformation, or other adverse changes, as well as the maximum water boiling (100°C) treatment time that the sample reaches level 1 or below in the 100-grid test.

[0131] (5) Vibration wear test

[0132] Test conditions:

[0133] a. Vibration wear tester: R180 / 530TE30 (equipment frequency: 50±0.5HZ, amplitude 1.65±0.1mm).

[0134] The volume ratio of mixed abrasive 15L: RKF10K (yellow cylinder) and RKK15P (green cone) is 3:1.

[0135] Detergent: Rosler FC120. The detergent (FC120) used in the test was diluted with water at a dilution ratio of 1:50 (volume ratio).

[0136] b. Test method

[0137] Pour 1L of water and 200mL of diluted detergent into the Rosler vibratory abrader containing the abrasive. Place the specimen into the abrasive with the head facing upward. Turn on the abrader. Add 0.5L of purified water every half hour while adjusting the orientation of the composite material as it is inserted into the abrasive. Take photos every half hour. Record the maximum vibration wear treatment time until the specimen's wear level reaches or falls below level 1.

[0138] Among them, the standards for wear levels 0-2 are:

[0139] Level 0: There is no obvious wear and damage on the large surface, corners and edges of the sample, and the color is as clear as before.

[0140] Level 1: The specimen has no wear on the large surface, and only the composite film layer at the corners and ridges has slight scratches and wear, but the wear does not expose the base material, and the area of ​​a single scratch is less than 1mm 2 .

[0141] Level 2: A small amount of point wear occurs on the large surface of the specimen, and the largest single wear area is less than 1mm 2 , or the edges and corners are worn through (leaking out the base material), and the maximum wear line width is less than 1mm.

[0142] The test results are shown in Table 1.

[0143] Table 1

[0144] Neutral salt spray test Artificial sweat test Boiling test Vibration wear test Example 1 96h 144h 2h 6h Example 2 72h 144h 2h 6h Example 3 72h 96h 1.5h 5h Example 4 48h 96h 1.5h 4h Example 5 72h 96h 2h 5h Example 6 72h 144h 2h 6h Example 7 48h 96h 2h 4h Example 8 48h 96h 1.5h 4h Example 9 48h 96h 1.5h 5h Comparative Example 1 24h 48h 1h 2.5h Comparative Example 2 24h 48h 1h 2.5h

[0145] It can be seen from the examples and comparative examples that the composite material provided by the present invention has good bonding strength between the film layer and the substrate, and has excellent wear resistance and corrosion resistance.

[0146] It can be seen from Comparative Examples 1-2 and the embodiments that when only one functional coating layer is provided, the wear resistance and corrosion resistance of the composite material are both reduced. After adding the second functional coating layer, the Al2O3 coating layer, the corrosion resistance of the composite film layer is enhanced by utilizing the high Vickers hardness and high resistance of the Al2O3 coating layer.

[0147] It can be seen from Examples 4 and 8 that the overall performance of the film layer is related to the thickness of the first functional coating layer and the second functional coating layer. The first functional coating layer has a suitable thickness, which is beneficial to improving its bonding strength with the base coating layer; the second functional coating layer with a suitable thickness can increase the overall resistance and hardness of the film layer and improve the wear resistance of the film layer.

[0148] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0149] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0150] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A composite material, characterized in that The composite material includes a substrate and an anodized film layer, a basic coating layer, a functional coating layer and a color coating layer arranged on one surface of the substrate in sequence from the inside to the outside, the functional coating layer includes a plurality of first functional coating layers and a plurality of second functional coating layers arranged alternately; the metal elements in the first functional coating layer are different from the metal elements in the second functional coating layer, or the first functional coating layer contains metal elements while the second functional coating layer does not contain metal elements; the metal elements are selected from one or more of Group IVB metals, Group VB metals, Group VIB metals and Group IVA metals.

2. The composite material according to claim 1, wherein The number of layers of the first functional coating layers and the number of layers of the second functional coating layers are each independently 2-10 layers.

3. The composite material according to claim 2, wherein The number of layers of the first functional coating layers and the number of layers of the second functional coating layers are each independently 3-8 layers.

4. The composite material according to claim 1, wherein The thickness of the first functional coating is 100-300 nm; and / or The thickness of the second functional coating is 50-150 nm.

5. The composite material according to any one of claims 1 to 4, wherein The first functional coating layer includes a first element and a second element, the first element is selected from at least one of Cr, Ti, Zr, W, Nb, Mo, Ta and Ge, and the second element is selected from C and / or N.

6. The composite material according to claim 5, wherein The first element in the first functional coating layer is partially or entirely the same as an element in the basic coating layer.

7. The composite material according to claim 5, wherein The first functional coating also contains O element.

8. The composite material according to any one of claims 1 to 4, 6 and 7, wherein: The second functional coating layer is selected from one or more of an aluminum oxide layer, a silicon oxide layer and a silicon nitride layer.

9. The composite material according to any one of claims 1 to 4, 6 and 7, wherein: The anodized film layer has a porous structure; and / or The pores in the anodized film have a pore diameter of 15-35 nm; and / or The porosity of the anodized film layer is 10-20%; and / or The thickness of the anodic oxide film layer is 5-15 μm.

10. The composite material according to any one of claims 1 to 4, 6 and 7, wherein: The substrate is an aluminum alloy; the element of the basic coating is selected from at least one of Cr, Ti, Zr, W, Nb, Mo, Ta and Ge.

11. The composite material according to any one of claims 1 to 4, 6 and 7, wherein: The color coating layer includes a third element and an optional fourth element, the third element is selected from at least one of Cr, Ti, W and Si, and the fourth element includes C and / or N.

12. The composite material according to any one of claims 1 to 4, 6 and 7, wherein: The thickness of the base coating is 100-300 nm; and / or The thickness of the color coating is 300-800 nm.

13. The composite material according to any one of claims 1 to 4, 6 and 7, wherein: The wear resistance of the composite material meets the following requirements: In the vibration wear test, the maximum vibration wear time for wear test results below level 1 is more than 4 hours; and / or The corrosion resistance of the composite material meets at least one of the following requirements: In the boiling test, the maximum boiling time for the cross-cut test result below level 1 is more than 1.5 hours; In the neutral salt spray test, if the cross-cut test result is below level 1, the maximum neutral salt spray treatment time is more than 48 hours; In the artificial sweat test, the maximum artificial sweat treatment time for a cross-cut test result below level 1 is more than 96 hours.

14. A method for preparing a composite material, characterized in that: The method comprises: performing anodizing on a substrate to obtain a substrate with an anodized film layer attached thereto; performing physical vapor deposition on the substrate with the anodized film layer attached thereto; The physical vapor deposition comprises the following steps: Performing a first magnetron sputtering on the substrate with the anodic oxide film layer attached thereto to deposit a basic coating layer on the surface of the anodic oxide film layer; Performing a second magnetron sputtering and a third magnetron sputtering alternately on the basic coating layer multiple times to deposit a functional coating layer on the surface of the basic coating layer; the functional coating layer includes a plurality of first functional coating layers and a plurality of second functional coating layers that are alternately arranged; performing a fourth magnetron sputtering on the surface of the functional coating layer to deposit a color coating layer on the surface of the functional coating layer; The metal element in the first functional coating is different from the metal element in the second functional coating, or the first functional coating contains a metal element while the second functional coating does not contain a metal element; the metal element is selected from one or more of Group IVB metals, Group VB metals, Group VIB metals, and Group IVA metals.

15. The method according to claim 14, wherein The anodizing step comprises the following steps: In a sulfuric acid solution, an anodic oxidation treatment is performed using graphite as a cathode and the substrate as an anode to obtain a substrate with the first anodic oxide film layer attached thereto.

16. The method according to claim 15, wherein The anodizing treatment time is 30-60 minutes; the voltage is 8-15V; and the sulfuric acid concentration is 100-200g / L.

17. The method according to claim 15 or 16, wherein The anodizing further comprises: placing the substrate with the first anodized film layer attached thereto in a phosphoric acid solution for pore expansion treatment to obtain a substrate with a second anodized film layer formed thereon.

18. The method according to claim 17, wherein The concentration of the phosphoric acid solution is 3-10 wt %; and the time for the pore expansion treatment is 2-10 minutes.

19. The method according to claim 14, wherein The number of the plurality of second magnetron sputtering operations and the number of the plurality of third magnetron sputtering operations are each independently 2 to 10 times.

20. The method according to claim 19, wherein The number of the plurality of second magnetron sputtering operations and the number of the plurality of third magnetron sputtering operations are each independently 3 to 8 times.

21. The method according to claim 14, wherein The conditions for the first magnetron sputtering include: the target material is at least one of Cr, Ti, Zr, W, Nb, Mo, Ta and Ge; and / or The conditions for the second magnetron sputtering include: the target material is at least one of Cr, Ti, Zr, W, Nb, Mo, Ta and Ge, and the reaction gas is nitrogen or acetylene; and / or The conditions of the third magnetron sputtering include: the target material is Al or Si; the reaction gas is oxygen or nitrogen; and / or The conditions for the fourth magnetron sputtering include: the target material is at least one of Cr, Ti, W and Si; and the reaction gas is nitrogen and / or acetylene.

22. The method according to claim 14, wherein The metal elements of the first functional coating layer are partially the same as or completely the same as the metal elements of the basic coating layer.

23. A housing, characterized in that: The shell comprises the composite material according to any one of claims 1-13.

24. An electronic device, characterized in that: The electronic device comprises the housing according to claim 23.

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