Diamond particle inlaid metal matrix diamond coating composite material and preparation method and application thereof

Abstract

The invention discloses a diamond particle inlaid metal matrix diamond coating composite material and a preparation method and application thereof.The preparation method comprises the steps that diamond particles are pressed and embedded in a metal substrate, the metal substrate inlaid with the diamond particles is obtained and subjected to heat treatment, then the metal substrate subjected to heat treatment is placed in nano-diamond seed crystal turbid liquid, seed crystals are planted, and the diamond particle inlaid metal matrix diamond coating composite material is obtained. The preparation method comprises the following steps: planting a seed crystal on a metal substrate to obtain a metal substrate for planting the seed crystal, and carrying out chemical vapor deposition on the metal substrate to grow a diamond film or a diamond-doped film, so as to obtain the diamond particle inlaid metal-based diamond coating composite material. The diamond film has the most obvious diamond phase and (111) crystal face preferred growth trend, the bonding strength of the diamond film and the substrate is high, and the diamond film has excellent conductivity and catalytic activity.

Description

Technical Field

[0001] The invention belongs to the technical field of diamond electrode preparation, and in particular relates to a diamond particle-inlaid metal-based diamond coating composite material and a preparation method and application thereof. Background Art

[0002] In the process of chemical vapor deposition of diamond film, due to the large difference in surface energy between diamond and substrate and the low adhesion of hydrocarbon groups, the growth of diamond on heterogeneous substrates usually leads to lower nucleation density, longer nucleation incubation period and slower deposition rate. Planting nanodiamond seeds on the substrate helps to increase the nucleation density, reduce the nucleation incubation period, accelerate the nucleation rate, reduce the voids generated in the nucleation stage, and improve the coating quality.

[0003] Nanodiamond particles are below 100nm in size and, like other nanoparticles, have an extremely high specific surface energy, which causes the particles to often exist in the form of agglomerates. Physical dispersion methods such as ultrasound and ball milling alone cannot achieve a good dispersion effect, which seriously affects their application in many important fields. Summary of the invention

[0004] In view of the shortcomings of the prior art, the first object of the present invention is to provide a method for preparing a diamond particle-embedded metal-based diamond coating composite material.

[0005] The second object of the present invention is to provide a diamond particle-embedded metal-based diamond coating composite material prepared by the above preparation method.

[0006] The third object of the present invention is to provide an application of a diamond particle-embedded metal-based diamond coating composite material.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The invention discloses a method for preparing a composite material of diamond particles embedded in a metal matrix and diamond coating. The method comprises the following steps: embedding diamond particles in a metal substrate to obtain a metal substrate embedded with diamond particles, performing heat treatment, and then placing the heat-treated metal substrate in a nano-diamond seed crystal suspension to plant seed crystals to obtain a metal substrate planted with seed crystals, and then performing chemical vapor deposition to grow a diamond film or a doped diamond film on the metal substrate to obtain the composite material of diamond particles embedded in a metal matrix and diamond coating.

[0009] The preparation method of the present invention comprises the following steps: pressing and embedding diamond particles on a flat metal substrate, wherein most of the diamond particles are embedded on the surface of the metal substrate; a small number of diamond particles fall off from the surface of the metal substrate, leaving pits on the metal substrate; both the protruding diamond particles and the pits can increase the specific surface area of ​​the metal substrate and effectively increase the nucleation sites during subsequent chemical vapor deposition of diamond, which is conducive to forming a dense and uniform diamond film with a large specific surface area, thereby enhancing the comprehensive performance of the diamond electrode; and then heat treatment is performed to cause a diffusion reaction between the diamond particles and the metal substrate, forming carbides at the interface, enhancing the interface bonding strength, making the embedded diamond particles act like rivets, greatly enhancing the bonding strength of the subsequent chemical vapor deposition diamond film layer; and finally, after planting seed crystals, a diamond film is obtained by chemical vapor deposition. The inventor unexpectedly finds that the diamond film grown on the metal substrate embedded with diamond particles has the most obvious diamond phase and (111) crystal plane preferential growth tendency, thereby further improving the performance of the diamond electrode.

[0010] In a preferred embodiment, the material of the metal substrate is selected from one of the metals nickel, niobium, tantalum, copper, titanium, cobalt, tungsten, molybdenum, chromium, iron or one of their alloys; or a composite material composed of one or more of the above metals and one or more of the ceramics A12O3, ZrO2, SiC, Si3N4, BN, B4C, AlN, TiB2, TiN, WC, Cr7C3, Ti2GeC, Ti2AlC and Ti2AlN, Ti3SiC2, Ti3GeC2, Ti3AlC2, Ti4AlC3, BaPO3.

[0011] The base metal substrate in the present invention includes a rod-shaped, tubular, two-dimensional continuous network structure and a two-dimensional closed flat plate structure.

[0012] In a preferred solution, the metal substrate is first etched with an oxalic acid solution at a temperature of 50° C.-70° C. for 1 to 3 hours, and the mass fraction of oxalic acid in the oxalic acid solution is 5% to 10%.

[0013] By etching the metal substrate with oxalic acid, not only can the oxide film on the surface of the metal substrate be removed, but the metal substrate can also be etched into a microporous structure, providing more active sites for the nucleation of diamond. However, the oxalic acid concentration cannot be too low or too high, and the etching time cannot be too short or too long, otherwise the oxalic acid will not be able to achieve the purpose of etching the metal substrate or the oxalic acid will over-etch and destroy the stability of the substrate. The temperature cannot be too high, otherwise the oxalic acid will decompose.

[0014] In a preferred solution, the diamond particles have a particle size of 250-500 μm. In the present invention, the particle size of the embedded diamonds needs to be effectively controlled. If it is not within the scope of the present invention, not only can it not be effectively embedded in the metal substrate, but the composite material finally produced will also have poor performance problems.

[0015] In a preferred embodiment, the diamond particles are embedded in the metal substrate by pressing, and the pressing pressure is 10 kN-20 kN.

[0016] Controlling the embedding pressure within the above range will ultimately provide the best performance. If the pressure is too small, the diamond particles cannot be embedded in the metal substrate, and if the pressure is too high, the substrate will crack.

[0017] In the actual operation process, the diamond particles are pressed into the etched metal substrate by mechanical pressing using a powder tablet press (hereinafter referred to as D-BDD).

[0018] In a preferred embodiment, the diamond particles are boron-doped diamond particles.

[0019] Preferably, the heat treatment temperature is 900-1025° C. After the heat treatment, the diamond particles and the metal substrate undergo a diffusion reaction to form carbides at the interface, thereby enhancing the interface bonding strength. If the temperature is too low, carbides cannot be formed, thereby reducing the bonding strength.

[0020] In a preferred embodiment, in the nano-diamond seed crystal suspension, the mass fraction of nano-diamond particles is 0.01%-0.05%, and the size of the nano-diamond particles is 10nm-100nm.

[0021] Further preferably, the nano-diamond seed crystal suspension contains a surfactant, and the mass fraction of the surfactant in the nano-diamond seed crystal suspension is 3-5wt%.

[0022] More preferably, the surfactant is selected from at least one of OP-10, polyisobutylene bissuccinimide (T154), sodium hexametaphosphate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, potassium chloride, sodium phosphate, polyethylene glycol, Tween, lysine, glutamic acid, etc. The inventors have found that the dispersion stability of nanodiamonds can be improved by appropriately adding surfactants to the nanodiamond seed crystal suspension.

[0023] In a preferred embodiment, the seed crystal planting method is selected from ultrasonic adsorption, electrostatic self-assembly, and electrophoretic deposition, preferably electrophoretic deposition. The above method can make the nano-diamond seed crystals planted and adsorbed on the surface of the metal substrate with high density.

[0024] Further preferably, when the method of planting the seed crystal is ultrasonic adsorption, the process of planting the seed crystal is: placing the heat-treated metal substrate in the nano-diamond seed crystal suspension, ultrasonically shaking for 5-30 minutes, and then rinsing with ultrapure water and drying.

[0025] Further preferably, when the method of planting the seed crystal is electrophoretic deposition, the process of planting the seed crystal is: placing the heat-treated metal substrate and the metal electrode together in the nano-diamond seed crystal suspension, applying a DC electric field, so that the nano-diamond particles are electrophoretically deposited on the metal of the metal substrate, and then rinsed and dried with ultrapure water. The distance between the metal substrate and the metal electrode is 5-15mm, the voltage of the applied DC electric field is 15-30V, and the time of electrophoretic deposition is 1-3min.

[0026] The inventors found that the electrophoresis technology has the advantages of simple equipment, controllable movement speed, and uniform deposition on special-shaped surfaces. When the electrophoresis technology is used to plant nano-diamond seed crystals, as the absolute value of the surface potential of the diamond particles in the suspension increases, the nucleation density on the substrate surface increases, which can greatly improve the uniformity of nucleation. Of course, in the process of operating nanomaterials using the electrophoresis technology, the suspension stability of the nanoparticles is the key in the technology. Since nano-diamonds are easy to agglomerate and stack, their suspension stability is poor, and nano-diamonds usually need to be surface modified. In the present invention, by appropriately adding a surfactant to the nano-diamond seed crystal suspension, the dispersion stability of nano-diamonds can be effectively improved.

[0027] In a preferred embodiment, the doped diamond film is a boron-doped diamond film.

[0028] In a preferred embodiment, during the chemical vapor deposition, the temperature of the metal substrate is 600-1000° C., and the growth time is 5-10 hours, preferably 8-10 hours.

[0029] The inventors also found that the diamond electrode made by mechanically pressing diamond particles on a metal substrate has the most obvious diamond phase and (111) crystal plane preferential growth trend on the electrode after 5 to 10 hours of growth, which further improves the performance of the diamond electrode. When diamond particles are not embedded in the metal substrate, the growth direction of the diamond film is not qualitative.

[0030] In a preferred embodiment, when a diamond film is grown by chemical vapor deposition, the mass flow ratio of the gases introduced is methane: hydrogen = 2-5: 90-96; when a doped diamond film is grown by chemical vapor deposition, the mass flow ratio of the gases introduced is methane: borane: hydrogen = 2-5: 2-5: 90-96.

[0031] In a preferred embodiment, the chemical vapor deposition is selected from at least one of hot wire chemical vapor deposition, microwave plasma chemical vapor deposition, DC plasma chemical vapor deposition, radio frequency ion chemical vapor deposition, flame combustion chemical vapor deposition, and DC jet plasma chemical vapor deposition, preferably hot wire chemical vapor deposition.

[0032] Further preferably, during the hot wire chemical vapor deposition, the temperature of the hot wire is controlled to be 1800-2500°C.

[0033] The present invention also provides a diamond particle-embedded metal-based diamond coating composite material prepared by the above preparation method.

[0034] The present invention also provides an application of a diamond particle inlaid metal-based diamond coating composite material prepared by the above preparation method, and the diamond particle inlaid metal-based diamond coating composite material is applied to one of electrochemical biosensors, electrochemical synthesis, and electrochemical detection.

[0035] The present invention also provides an application of a diamond particle embedded metal-based diamond coating composite material prepared by the above preparation method, and the diamond particle embedded metal-based diamond coating composite material is applied to degrading organic wastewater.

[0036] Principles and advantages

[0037] The preparation method of the present invention comprises the following steps: pressing and embedding diamond particles on a flat metal substrate, wherein most of the diamond particles are embedded on the surface of the metal substrate; a small number of diamond particles fall off from the surface of the metal substrate, leaving pits on the metal substrate; both the protruding diamond particles and the pits can increase the specific surface area of ​​the metal substrate and effectively increase the nucleation sites during subsequent chemical vapor deposition of diamond, which is conducive to forming a dense and uniform diamond film with a large specific surface area, thereby enhancing the comprehensive performance of the diamond electrode; and then heat treatment is performed to cause a diffusion reaction between the diamond particles and the metal substrate, forming carbides at the interface, enhancing the interface bonding strength, making the embedded diamond particles act like rivets, greatly enhancing the bonding strength of the subsequent chemical vapor deposition diamond film layer; and finally, after planting seed crystals, a diamond film is obtained by chemical vapor deposition. The inventor unexpectedly finds that the diamond film grown on the metal substrate embedded with diamond particles has the most obvious diamond phase and (111) crystal plane preferential growth tendency, thereby further improving the performance of the diamond electrode.

[0038] The diamond particle-embedded metal-based diamond coating composite material prepared by the preparation method of the present invention has a diamond film with the most obvious diamond phase and (111) crystal plane preferential growth trend, a high bonding strength between the diamond film and the substrate, and excellent electrical conductivity and catalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The XRD pattern of the BDD electrode obtained in the embodiment, wherein: Figure 1 Ti / D-BDD5 in (a) is the XRD pattern of the diamond particle embedded metal-based diamond coating composite material obtained in Example 1, and Ti-BDD5 is the XRD pattern of the metal-based diamond coating composite material which is also chemically vapor deposited for 5 hours but is not embedded with diamond particles. Figure 1 Ti / D-BDD in (b) 10 XRD pattern of the diamond particle embedded metal-based diamond coating composite material obtained in Example 2, Ti / D-BDD 10 The XRD pattern of the metal-based diamond coating composite material is also chemical vapor deposition for 10 hours, but without embedded diamond particles. From the XRD spectrum, it can be seen that Ti / D-BDD5 (embedded electrode) has obvious traces of Ti-C bonds compared with Ti / BDD without embedding, proving that the embedded diamond particles are well combined with the metal substrate. 10 Compared with Ti / D-BDD5, it can be seen that the surface of the substrate is basically covered by the diamond film grown in a directional (111) direction; at the same time, it can be seen that after the same growth of 10 hours, there are still many traces of metals and their compounds on the surface of the substrate without embedded diamond particles, which indicates that the surface of the substrate without embedded diamond particles is not completely covered by the diamond film.

[0040] Figure 2 The chromaticity removal rate and energy consumption of OG oxidized by different BDD electrodes. From the figure, we can see that Ti / D-BDD 10 The degradation effect is optimal. DETAILED DESCRIPTION

[0041] Example 1

[0042] A titanium substrate is used, and the titanium substrate is etched with an oxalic acid solution, the etching temperature is 65°C, the etching time is 1 hour, the mass fraction of oxalic acid in the oxalic acid solution is 5%, and then 400-500 μm diamond particles are taken, and the boron-doped diamond particles are pressed into the etched metal substrate by a powder tablet press in a mechanical pressing manner, and the pressing pressure is controlled to be 15 kN to obtain a metal substrate inlaid with boron-doped diamond particles, and the metal substrate is controlled to be heat treated at 900°C to obtain a heat-treated metal substrate. Nano-diamond seed crystals of 10nm-100nm and OP-10 are added into water to obtain nano-diamond seed crystal suspension, wherein the mass fraction of nano-diamond particles is 0.03%, and the mass fraction of surfactant in the nano-diamond seed crystal suspension is 4wt%. Then, a heat-treated metal substrate is placed in the nano-diamond seed crystal suspension, subjected to ultrasonic oscillation treatment for 20min, and then rinsed and dried with ultrapure water to obtain a metal substrate planted with seed crystals. A diamond film is deposited on the metal substrate planted with seed crystals by hot-wire chemical vapor deposition. During the chemical vapor deposition, the temperature of the metal substrate is 1000°C, the temperature of the hot wire is 2100°C, the growth time is 5h, and the mass flow ratio of the introduced gas is methane:borane:hydrogen=2:3:95, so as to obtain a composite material of diamond particles embedded in a metal-based diamond coating (abbreviated as Ti / D-BDD5). The glucose degradation experiment was then carried out. The experimental results showed that the COD degradation rate reached 90% within 4 hours. The corresponding degradation experiment of the electrode sheet without diamond particles (referred to as Ti / -BDD5) showed that the COD removal rate was 79.7%. Compared with the BDD electrode without inlay treatment, the performance was improved by 10.3%, and the energy consumption was reduced by 9.6%.

[0043] Example 2

[0044] A titanium substrate is used, and the titanium substrate is etched with an oxalic acid solution. The etching temperature is 65°C, the etching time is 1 hour, the mass fraction of oxalic acid in the oxalic acid solution is 5%, and then 250-400 μm diamond particles are taken, and the boron-doped diamond particles are pressed into the etched metal substrate by a powder tablet press. The pressing pressure is controlled to be 10 kNkN, and a metal substrate inlaid with diamond particles is obtained, which is referred to as D-BDD. The metal substrate is controlled to be heat treated at 900°C to obtain a heat-treated metal substrate. Nano-diamond seed crystals of 10nm-100nm and OP-10 are added into water to obtain nano-diamond seed crystal suspension, wherein the mass fraction of nano-diamond particles is 0.05%, and the mass fraction of surfactant in the nano-diamond seed crystal suspension is 4wt%. Then, the heat-treated metal substrate is placed in the nano-diamond seed crystal suspension, subjected to ultrasonic oscillation treatment for 30min, and then rinsed and dried with ultrapure water to obtain a metal substrate planted with seed crystals. A diamond film is deposited on the metal substrate planted with seed crystals by hot wire chemical vapor deposition. During the chemical vapor deposition, the temperature of the metal substrate is 1000°C, the temperature of the hot wire is 2100°C, the growth time is 10h, and the mass flow ratio of the introduced gas is methane: borane: hydrogen = 2:3:95, so as to obtain a diamond particle-embedded metal-based diamond coating composite material (abbreviated as Ti / D-BDD) 10 The glucose degradation experiment was then carried out. The experimental results showed that the COD degradation rate reached 90% within 4 hours, while the electrode without diamond particles (Ti / BDD 10 ))'s corresponding degradation experiments showed that the COD removal efficiency was 78%. Compared with the BDD electrode without inlay treatment, the performance was improved by 12% and the energy consumption was reduced by 13.2%.

[0045] Comparative Example 1

[0046] A titanium substrate is used, and the titanium substrate is etched with an oxalic acid solution. The etching temperature is 65° C., the etching time is 1 hour, and the mass fraction of oxalic acid in the oxalic acid solution is 5%. Then, pure diamond particles (not BDD) of 4000-500 μm are taken, and the diamond particles are pressed into the etched metal substrate by a powder tablet press. The pressing pressure is controlled to be 10 kN to obtain a metal substrate inlaid with diamond particles. The metal substrate is controlled to be heat treated at 900° C. to obtain a heat-treated metal substrate. Nano-diamond seed crystals of 10nm-100nm and OP-10 are added into water to obtain nano-diamond seed crystal suspension, wherein the mass fraction of nano-diamond particles is 0.002%, and the mass fraction of surfactant in the nano-diamond seed crystal suspension is 3wt%. Then, a heat-treated metal substrate is placed in the nano-diamond seed crystal suspension, subjected to ultrasonic oscillation treatment for 20 minutes, and then rinsed and dried with ultrapure water to obtain a metal substrate planted with seed crystals. A diamond film is deposited on the metal substrate planted with seed crystals by hot wire chemical vapor deposition. During the chemical vapor deposition, the temperature of the metal substrate is 1000°C, the temperature of the hot wire is 2100°C, the growth time is 5h, and the mass flow ratio of the introduced gas is methane:borane:hydrogen=2:3:95, so as to obtain a boron-doped diamond diamond coating material. Then, a glucose degradation experiment was carried out. The experimental results showed that the COD degradation rate reached 80% within 4 hours, while the corresponding degradation experiment of the electrode sheet without inlaid diamond particles showed that the COD removal rate was 79.7%, which was almost the same as that of the BDD electrode without inlay treatment.

Claims

1. A method for preparing a composite material of diamond particles embedded in metal and diamond coating, characterized in that: Diamond particles are pressed into a metal substrate to obtain a metal substrate inlaid with diamond particles, which is then heat treated. The heat-treated metal substrate is then placed in a nano-diamond seed crystal suspension to plant seed crystals to obtain a metal substrate planted with seed crystals. The metal substrate is then chemically vapor deposited to grow a diamond film or a doped diamond film to obtain a diamond particle-inlaid metal-based diamond coating composite material.

2. The method for preparing a composite material of diamond particles embedded in metal and diamond coating according to claim 1, characterized in that: The material of the metal substrate is selected from one of the metals nickel, niobium, tantalum, copper, titanium, cobalt, tungsten, molybdenum, chromium, iron or one of their alloys; or a composite material composed of one or more of the above metals and one or more of the ceramics A12O3, ZrO2, SiC, Si3N4, BN, B4C, AlN, TiB2, TiN, WC, Cr7C3, Ti2GeC, Ti2AlC and Ti2AlN, Ti3SiC2, Ti3GeC2, Ti3AlC2, Ti4AlC3, BaPO3; The metal substrate is first etched with an oxalic acid solution at a temperature of 50° C.-70° C. for 1 to 3 hours. The mass fraction of oxalic acid in the oxalic acid solution is 5% to 10%.

3. The method for preparing a composite material of diamond particles embedded in metal and diamond coating according to claim 1, characterized in that: The particle size of the diamond particles is 250-500 μm; The diamond particles are embedded in the metal substrate by pressing, and the pressing pressure is 10kN-20kN; The diamond particles are boron-doped diamond particles.

4. The method for preparing a composite material of diamond particles embedded in metal and diamond coating according to claim 1, characterized in that: The temperature of the heat treatment is 900-1025°C.

5. The method for preparing a composite material of diamond particles embedded in metal and diamond coating according to claim 1, characterized in that: In the nano-diamond seed crystal suspension, the mass fraction of nano-diamond particles is 0.01%-0.05%, and the size of the nano-diamond particles is 10nm-100nm; The nano-diamond seed crystal suspension contains a surfactant, and the mass fraction of the surfactant in the nano-diamond seed crystal suspension is 3-5wt%.

6. The method for preparing a composite material of diamond particles embedded in metal and diamond coating according to claim 5, characterized in that: The surfactant is selected from at least one of OP-10, polyisobutylene bissuccinimide, sodium hexametaphosphate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, potassium chloride, sodium phosphate, polyethylene glycol, Tween, lysine, glutamic acid and the like.

7. The method for preparing a diamond particle-embedded metal-based diamond coating composite material according to claim 1 or 5, characterized in that: The method of planting the seed crystal is selected from one of ultrasonic adsorption, electrostatic self-assembly, and electrophoretic deposition; When the method of planting the seed crystal is ultrasonic adsorption, the process of planting the seed crystal is as follows: placing the heat-treated metal substrate in the nano-diamond seed crystal suspension, ultrasonically shaking for 5-30 minutes, and then washing and drying with ultrapure water; When the method of planting the seed crystal is electrophoretic deposition, the process of planting the seed crystal is: placing the heat-treated metal substrate and the metal electrode together in the nano-diamond seed crystal suspension, applying a DC electric field, so that the nano-diamond particles are electrophoretically deposited on the metal of the metal substrate, and then rinsed and dried with ultrapure water. The distance between the metal substrate and the metal electrode is 5-15mm, the voltage of the applied DC electric field is 15-30V, and the time of electrophoretic deposition is 1-3min.

8. The method for preparing a composite material of diamond particles embedded in metal and diamond coating according to claim 1, characterized in that: The doped diamond film is a boron-doped diamond film; During the chemical vapor deposition, the temperature of the metal substrate is 600-1000° C., and the growth time is 5-10 hours. When chemical vapor deposition is used to grow diamond films, the mass flow ratio of the gases introduced is methane: hydrogen = 2-5: 90-96; when chemical vapor deposition is used to grow doped diamond films, the mass flow ratio of the gases introduced is methane: borane: hydrogen = 2-5: 2-5: 90-96; The chemical vapor deposition is selected from at least one of hot wire chemical vapor deposition, microwave plasma chemical vapor deposition, DC plasma chemical vapor deposition, radio frequency ion chemical vapor deposition, flame combustion chemical vapor deposition, and DC jet plasma chemical vapor deposition.

9. A diamond particle-embedded metal-based diamond coating composite material prepared by the preparation method according to any one of claims 1 to 8.

10. Use of a diamond particle-embedded metal-based diamond coating composite material prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The diamond particle inlaid metal-based diamond coating composite material is applied to one of electrochemical biosensors, electrochemical synthesis and electrochemical detection.

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