BDD film material based on silicon carbide fiber cloth and preparation method and application thereof

Abstract

The invention discloses a BDD film material based on silicon carbide fiber cloth and a preparation method and application thereof, and belongs to the technical field of materials. The BDD thin film material comprises silicon carbide fiber cloth serving as a base body, a metal tungsten layer deposited on the upper surface of the silicon carbide fiber cloth and a diamond film layer growing on the surface of the metal tungsten. The invention also discloses a preparation method of the BDD thin film material and application of the BDD thin film material as an electrochemical oxidation anode material. Compared with a common BDD electrode with a planar two-dimensional substrate, the BDD film material prepared from the silicon carbide fiber cloth substrate has the advantages that the specific surface area is increased, and the degradation efficiency of electrochemically removing high-difficulty organic wastewater is improved. The invention further discloses a preparation method of the BDD thin film material based on the silicon carbide fiber cloth, the method is easy to operate, and high-quality, efficient and rapid preparation of the BDD thin film material can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode materials, and particularly to a BDD thin film material based on silicon carbide fiber cloth, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, advanced oxidation processes (AOPs) have been regarded as an effective means for removing refractory biodegradable organic pollutants. As a branch of advanced oxidation processes, electrochemical oxidation technology, also known as electrochemical advanced oxidation processes (EAOPs), mainly oxidizes and removes pollutants in wastewater through electrode reactions, and has received increasing attention in the field of wastewater treatment in recent years. The anode material is the core of electrochemical oxidation technology. The electrochemical degradation reaction of refractory biodegradable organic pollutants occurs at the anode / solution interface. Therefore, the properties of the anode material play a crucial role in terms of degradation efficiency, degradation mechanism, and selectivity. Selecting an anode material that can economically and efficiently degrade organic wastewater has always been the research focus in the field of electrochemical oxidation. An ideal electrochemical oxidation anode material should have the following characteristics: (1) having a wide potential window and a high oxygen evolution potential; (2) good electrical conductivity; (3) stable physical and chemical properties and corrosion resistance; (4) stable mechanical properties and a long service life, etc. Currently, the commonly used anode materials for electrochemical oxidation technology are divided into metal electrodes, metal oxide electrodes, carbon electrodes, and boron-doped diamond (BDD) electrodes.

[0003] Generally, an ideal anode for pollutant degradation must have a high oxygen evolution potential to reduce the occurrence of oxygen evolution side reactions. Due to their low activity, low stability, and low durability, the above-mentioned traditional anode materials are not sufficient for efficient electrochemical oxidation. In recent years, it has been found through research that diamond films have excellent properties such as high resistance, high thermal conductivity, and high chemical stability. After boron doping, the prepared boron-doped diamond has good electrical conductivity and semiconductor properties, and its oxygen evolution potential and electrocatalytic performance are significantly improved, and it can be used as an anode material for electrochemical oxidation with a wide potential window. Therefore, BDD electrodes are considered to be ideal and efficient anode materials in electrochemical oxidation, and their advantages mainly include: (1) an extremely wide electrochemical window; (2) an extremely high oxygen evolution potential; (3) an extremely low background current; (4) excellent chemical stability; (5) excellent anti-adsorption performance; (6) excellent mechanical properties. Based on the above advantages, BDD electrodes are widely used in the field of electrocatalytic oxidation. As an anode material for electrochemical oxidation, they have a higher degradation efficiency than other anode materials, are clean and pollution-free, and can be reused.

[0004] Traditional BDD electrodes currently mainly use heavily doped silicon or metal as the matrix. As a semiconductor material, silicon has a large resistance. After forming a silicon / BDD composite electrode, the impedance heat generated during the electrochemical electrolysis treatment is large, which increases the energy consumption of wastewater treatment. Although metal substrates (such as tungsten, molybdenum, niobium, etc.) have good mechanical and electrical properties, the metal / BDD composite electrode formed has weak bonding force due to the great difference in thermal expansion coefficient with diamond. In addition, since hydrogen must be used in the chemical vapor deposition process of BDD electrodes to etch away the graphite and amorphous carbon associated with diamond growth, the resulting impact is that if silicon carbide is used as the matrix, the high concentration of hydrogen used in diamond growth will also severely etch the silicon carbide matrix, which not only destroys the matrix structure, but also makes the diamond growth atmosphere environment out of control, making it difficult to form a complete diamond film on the surface. Most traditional BDD electrodes are planar 2D structures with small electrochemical active areas and low mass transfer rates, which have become technical problems that need to be solved urgently in the relevant technical field. Summary of the invention

[0005] The purpose of the present invention is to provide a BDD film material based on silicon carbide fiber cloth, a preparation method and an application thereof, so that the grown BDD film has larger electrochemical active sites due to the larger specific surface area of ​​the silicon carbide fiber cloth, thereby improving the electrochemical active area and mass transfer rate.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] On one hand, the present invention discloses a BDD film material based on silicon carbide fiber cloth, which includes silicon carbide fiber cloth as a substrate, a metal tungsten layer deposited on the upper surface of the silicon carbide fiber cloth, and a diamond film layer grown on the surface of the metal tungsten layer.

[0008] In some embodiments of the present invention, the thickness of the metal tungsten layer is 0.18-0.25 mm.

[0009] In some embodiments of the present invention, the thickness of the diamond film layer is 1 to 150 μm.

[0010] Another aspect of the present invention discloses a method for preparing a BDD thin film material based on silicon carbide fiber cloth, the preparation method comprising the following steps:

[0011] S1. Sintering pretreatment: performing sintering pretreatment on the silicon carbide fiber cloth;

[0012] S2. Depositing metallic tungsten: placing the sintered silicon carbide fiber cloth as a substrate in the reaction chamber of the HFCVD equipment, electrifying the tungsten filament in the reaction chamber to make the temperature of the tungsten filament reach a first temperature, introducing carbonyl tungsten vapor to decompose the carbonyl tungsten vapor on the surface of the silicon carbide fiber cloth substrate and depositing a layer of metallic tungsten;

[0013] S3. Growing diamond film: Adjust the tungsten wire power supply, raise the temperature of the tungsten wire to the second temperature, introduce methane, borane, and hydrogen into the reaction chamber, and grow a layer of diamond film on the surface of the deposited tungsten metal.

[0014] In some embodiments of the present invention, in S1, the sintering temperature is 550 - 650 °C, the sintering time is 10 - 60 min. Preferably, the sintering temperature is 600 °C and the sintering time is 30 min.

[0015] In some embodiments of the present invention, in S2, place the silicon carbide fiber cloth as the substrate in the reaction chamber of the HFCVD equipment, and evacuate the reaction chamber; preferably, evacuate the reaction chamber to 1.0 - 3.0 Pa.

[0016] In some embodiments of the present invention, in S2, the first temperature is 1100 - 1500 °C, preferably 1200 - 1400 °C;

[0017] In S2, the introduction time of tungsten carbonyl vapor is 1.5 - 2 h.

[0018] In some embodiments of the present invention, in S3, the second temperature is 2000 - 2420 °C, preferably 2100 - 2300 °C.

[0019] In some embodiments of the present invention, the gas flow rates of the methane, borane, and hydrogen are 20 - 40 cm 3 / min, 10 - 30 cm 3 / min, and 300 - 500 cm 3 .

[0020] The third aspect of the present invention discloses the application of the BDD thin film material based on silicon carbide fiber cloth as an electrochemical oxidation anode material.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The BDD thin film material prepared by the present invention using a silicon carbide fiber cloth substrate has a four - fold increase in specific surface area compared with the BDD electrodes of common planar two - dimensional substrates (such as silicon, niobium, etc.), and the degradation efficiency of electrochemically removing high - difficulty organic wastewater is increased by 30%. Brief Description of the Drawings

[0023] Figure 1 It is a preparation schematic diagram of the present invention. Detailed Embodiments

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0026] The BDD thin film material based on silicon carbide fiber cloth provided by the present invention includes silicon carbide fiber cloth as the matrix, a tungsten metal layer deposited on the upper surface of the silicon carbide fiber cloth, and a diamond film layer grown on the surface of the tungsten metal layer. In the BDD thin film material of the present invention, tungsten metal serves as an intermediate transition layer, and the diamond film is grown on the surface of the intermediate transition layer. The BDD thin film material prepared by using the silicon carbide fiber cloth matrix of the present invention has a four-fold increase in specific surface area and a 30% increase in the degradation efficiency of electrochemical removal of highly difficult organic wastewater compared with the commonly used planar two-dimensional substrate BDD electrode.

[0027] Further, the thickness of the tungsten metal layer is 0.18 - 0.25 mm, preferably 0.20 mm.

[0028] Further, the thickness of the diamond film layer is 1 - 150 μm, preferably 3 - 100 μm.

[0029] The present invention also provides a preparation method of the BDD thin film material based on silicon carbide fiber cloth, including the following steps:

[0030] S1. Perform sintering pretreatment on the silicon carbide fiber cloth, the sintering temperature is 550 - 650 °C, the sintering time is 10 - 60 min, preferably, the sintering temperature is 600 °C and the sintering time is 30 min;

[0031] S2. Place the sintered silicon carbide fiber cloth as the substrate in the reaction chamber of the HFCVD equipment, evacuate the reaction chamber, preferably to 1.0 - 3.0 Pa; energize the tungsten wire in the reaction chamber to make the temperature of the tungsten wire reach the first temperature, and introduce tungsten carbonyl vapor to decompose the tungsten carbonyl vapor on the surface of the silicon carbide fiber cloth substrate and deposit a layer of metallic tungsten; the first temperature is 1100 - 1500 °C, preferably 1200 - 1400 °C;

[0032] S3. Adjust the tungsten wire power supply to raise the temperature of the tungsten wire to the second temperature, introduce methane, borane and hydrogen into the reaction chamber, and grow a layer of diamond film on the surface of the deposited metallic tungsten; the second temperature is 2000 - 2420 °C, preferably 2100 - 2300 °C.

[0033] In the present invention, the sintering pretreatment of S1 is carried out in a tube furnace, and the role of sintering is to remove impurities such as binders in the substrate.

[0034] In the present invention, the evacuation in S2 forms a high vacuum atmosphere in the reaction chamber of the HFCVD equipment to prevent impurities from being incorporated during the growth process.

[0035] In the present invention, the tungsten carbonyl vapor in S2 is the tungsten carbonyl vapor formed by gasification through constant temperature water bath heating, and the introduction time of the tungsten carbonyl vapor is 1.5 - 2 h.

[0036] In the present invention, methane, borane and hydrogen are introduced in S3. Methane (CH 4 ) and hydrogen (H 2 ) serve as reaction gas sources, and borane (B 2 H 6 ) serves as a doping gas source. The growth rate of the diamond film is 0.5 - 1.0 μm / h, preferably 0.51 μm / h. In the present invention, the required thickness of the diamond film is achieved by controlling the growth time.

[0037] In some embodiments of the present invention, the gas flow rates of methane, borane and hydrogen are 20 - 40 cm 3 , 10 - 30 cm 3 and 300 - 500 cm 3 per minute, respectively.

[0038] The power of the HFCVD system used in the embodiments of the present invention is 20 kW.

[0039] Example 1

[0040] This example discloses a preparation method of the BDD thin film material based on silicon carbide fiber cloth of the present invention, and the specific steps are as follows:

[0041] S1. Sinter the silicon carbide fiber cloth as a pretreatment to remove impurities, with a sintering temperature of 600 °C and a sintering time of 30 min;

[0042] S2. Place the sintered silicon carbide fiber cloth as a substrate in the reaction chamber of the HFCVD equipment, and evacuate the reaction chamber to 1.0 Pa; energize the tungsten wire in the reaction chamber to make the temperature of the tungsten wire reach 1400 °C, and introduce tungsten carbonyl vapor to decompose the tungsten carbonyl vapor on the surface of the silicon carbide fiber cloth substrate and deposit a layer of metallic tungsten;

[0043] Among them, the tungsten carbonyl vapor is the tungsten carbonyl vapor formed by vaporization through constant-temperature water bath heating, and the introduction time of the tungsten carbonyl vapor is 1.5 h.

[0044] S3. Adjust the tungsten wire power supply to raise the temperature of the tungsten wire to 2300 °C, introduce methane, borane and hydrogen into the reaction chamber, and grow a layer of diamond film on the surface of the deposited metallic tungsten; the flow rates of methane, borane and hydrogen are 30 cm 3 / min, 20 cm 3 / min and 400 cm 3 / min.

[0045] The growth rate of the diamond film is 0.51 μm / h. Control the growth time to obtain a diamond film layer with a thickness of 3 μm.

[0046] The thickness of the metallic tungsten layer of the BDD thin film material prepared in this example is 0.2 mm, and the thickness of the diamond film layer is 3 μm.

[0047] Example 2

[0048] This example discloses a preparation method of the BDD thin film material based on silicon carbide fiber cloth of the present invention, and the specific steps are as follows:

[0049] S1. Sinter the silicon carbide fiber cloth as a pretreatment to remove impurities, with a sintering temperature of 550 °C and a sintering time of 60 min;

[0050] S2. Place the sintered silicon carbide fiber cloth as a substrate in the reaction chamber of the HFCVD equipment, and evacuate the reaction chamber to 3.0 Pa; energize the tungsten wire in the reaction chamber to make the temperature of the tungsten wire reach 1200 °C, and introduce tungsten carbonyl vapor to decompose the tungsten carbonyl vapor on the surface of the silicon carbide fiber cloth substrate and deposit a layer of metallic tungsten;

[0051] Among them, the tungsten carbonyl vapor is the tungsten carbonyl vapor formed by vaporization through constant-temperature water bath heating, and the introduction time of the tungsten carbonyl vapor is 1.5 h.

[0052] S3. Adjust the tungsten wire power supply, raise the temperature of the tungsten wire to 2100 °C, introduce methane, borane and hydrogen into the reaction chamber, and grow a layer of diamond film on the surface of the deposited metallic tungsten; the flow rates of methane, borane and hydrogen are 40 cm 3 / min, 30 cm 3 / min and 500 cm 3 / min respectively.

[0053] The growth rate of the diamond film is 0.6 μm / h. Control the growth time to obtain a diamond film layer with a thickness of 20 μm.

[0054] The thickness of the metallic tungsten layer of the BDD thin film material prepared in this example is 0.18 mm, and the thickness of the diamond film layer is 20 μm.

[0055] Example 3

[0056] This example discloses a preparation method of a BDD thin film material based on a silicon carbide fiber cloth according to the present invention. The specific steps are as follows:

[0057] S1. Perform sintering pretreatment on the silicon carbide fiber cloth to remove impurities. The sintering temperature is 650 °C and the sintering time is 10 min;

[0058] S2. Place the sintered silicon carbide fiber cloth as the substrate in the reaction chamber of the HFCVD equipment, evacuate the reaction chamber to 2.0 Pa; energize the tungsten wire in the reaction chamber to raise the temperature of the tungsten wire to 1500 °C, and introduce tungsten carbonyl vapor to decompose and deposit a layer of metallic tungsten on the surface of the silicon carbide fiber cloth substrate;

[0059] Among them, the tungsten carbonyl vapor is formed by vaporization through water bath constant temperature heating, and the introduction time of the tungsten carbonyl vapor is 1.5 h.

[0060] S3. Adjust the tungsten wire power supply, raise the temperature of the tungsten wire to 2420 °C, introduce methane, borane and hydrogen into the reaction chamber, and grow a layer of diamond film on the surface of the deposited metallic tungsten; the flow rates of methane, borane and hydrogen are 20 cm 3 / min, 10 cm 3 / min and 300 cm 3 / min respectively.

[0061] The growth rate of the diamond film is 0.4 μm / h. Control the growth time to obtain a diamond film layer with a thickness of 50 μm.

[0062] The thickness of the metallic tungsten layer of the BDD thin film material prepared in this example is 0.22 mm, and the thickness of the diamond film layer is 50 μm.

[0063] Example 4

[0064] This embodiment discloses a preparation method of the BDD thin film material based on silicon carbide fiber cloth according to the present invention. The specific steps are as follows:

[0065] S1. Perform sintering pretreatment on the silicon carbide fiber cloth to remove impurities. The sintering temperature is 600 °C and the sintering time is 60 min;

[0066] S2. Place the sintered silicon carbide fiber cloth as the substrate in the reaction chamber of the HFCVD equipment, and evacuate the reaction chamber to 2.0 Pa; energize the tungsten wire in the reaction chamber to make the temperature of the tungsten wire reach 1100 °C, and introduce tungsten carbonyl vapor to decompose the tungsten carbonyl vapor on the surface of the silicon carbide fiber cloth substrate and deposit a layer of metallic tungsten;

[0067] Among them, the tungsten carbonyl vapor is the tungsten carbonyl vapor formed by gasification through constant-temperature water bath heating, and the introduction time of the tungsten carbonyl vapor is 2 h.

[0068] S3. Adjust the tungsten wire power supply to raise the temperature of the tungsten wire to 2000 °C, introduce methane, borane and hydrogen into the reaction chamber, and grow a layer of diamond film on the surface of the deposited metallic tungsten; the flow rates of methane, borane and hydrogen are 25 cm 3 / min, 20 cm 3 / min and 350 cm 3 / min respectively.

[0069] The growth rate of the diamond film is 0.45 μm / h. Control the growth time to obtain a diamond film layer with a thickness of 100 μm.

[0070] The thickness of the metallic tungsten layer of the BDD thin film material prepared in this embodiment is 0.25 mm, and the thickness of the diamond film layer is 100 μm.

[0071] Comparative Example 1

[0072] Compared with Example 1, in this Comparative Example 1, the substrate is replaced with a graphite substrate instead of the silicon carbide fiber cloth, and there is no S1. Directly perform S2 and S3; obtain the graphite substrate BDD material.

[0073] Test Example 1

[0074] Respectively investigate the performances of the BDD thin film materials based on silicon carbide fiber cloth in Examples 1 to 4 and the graphite substrate BDD material prepared in Comparative Example 1. The results are shown in the following table:

[0075] Table 1 Investigation results of the performances of BDD thin film materials with different substrates

[0076]

[0077] As can be seen from Table 1, the BDD thin film material based on silicon carbide fiber cloth of the present invention has better corrosion resistance than the graphite matrix BDD material with graphite as the matrix, and the COD removal efficiency of organic wastewater has been improved.

[0078] Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention to illustrate the technical solutions of the present invention, rather than limiting it, let alone limiting the patent scope of the present invention; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; that is to say, any meaningless changes or polishings made in the main design idea and spirit of the present invention, as long as the technical problems solved are still the same as those of the present invention, should be included in the protection scope of the present invention; in addition, directly or indirectly applying the technical solutions of the present invention to other related technical fields shall also be included in the patent protection scope of the present invention by the same token.

Claims

1. BDD film material based on silicon carbide fiber cloth, characterized in that: The invention comprises a silicon carbide fiber cloth as a substrate, a metal tungsten layer deposited on the surface of the silicon carbide fiber cloth, and a diamond film layer grown on the surface of the metal tungsten layer.

2. The BDD thin film material based on silicon carbide fiber cloth according to claim 1, characterized in that: The thickness of the metal tungsten layer is 0.18-0.25 mm.

3. The BDD thin film material based on silicon carbide fiber cloth according to claim 1 or 2, characterized in that: The thickness of the diamond film layer is 1 to 150 μm.

4. The method for preparing a BDD thin film material based on silicon carbide fiber cloth according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Sintering pretreatment: performing sintering pretreatment on the silicon carbide fiber cloth; S2. Depositing metallic tungsten: placing the sintered silicon carbide fiber cloth as a substrate in the reaction chamber of the HFCVD equipment, electrifying the tungsten filament in the reaction chamber to make the temperature of the tungsten filament reach a first temperature, introducing carbonyl tungsten vapor to decompose the carbonyl tungsten vapor on the surface of the silicon carbide fiber cloth substrate and deposit a layer of metallic tungsten; S3. Growing a diamond film: adjusting the tungsten filament power supply, raising the tungsten filament temperature to a second temperature, introducing methane, borane and hydrogen into the reaction chamber, and growing a layer of diamond film on the surface of the deposited metallic tungsten.

5. The method for preparing the BDD thin film material based on silicon carbide fiber cloth according to claim 4, characterized in that: In the above-mentioned S1, the sintering temperature is 550-650° C. and the sintering time is 10-60 min.

6. The method for preparing the BDD thin film material based on silicon carbide fiber cloth according to claim 4, characterized in that: In S2, the silicon carbide fiber cloth is placed as a substrate in a reaction chamber of a HFCVD device, and the reaction chamber is evacuated.

7. The method for preparing a BDD thin film material based on silicon carbide fiber cloth according to claim 4, characterized in that: In S2, the first temperature is 1100-1500° C.; In S2, the introduction time of carbonyl tungsten vapor is 1.5 to 2 hours.

8. The method for preparing a BDD thin film material based on silicon carbide fiber cloth according to claim 4, characterized in that: In S3, the second temperature is 2000-2420°C, preferably 2100-2300°C.

9. The method for preparing a BDD thin film material based on silicon carbide fiber cloth according to claim 4, characterized in that: The gas flow rates of methane, borane and hydrogen are 20-40 cm / min respectively. 3 , 10~30cm 3 and 300~500cm 3 .

10. Use of the BDD thin film material based on silicon carbide fiber cloth according to any one of claims 1 to 3 as an electrochemical oxidation anode material.

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