Titanium-based boron-doped diamond semiconductor composite coating material, and preparation method and application thereof

Abstract

The application discloses a titanium-based boron-doped diamond semiconductor composite coating material and a preparation method and application thereof. The titanium-based boron-doped diamond semiconductor composite coating material is composed of a titanium base, a Ti-B compound gradient transition layer arranged on the surface of the titanium base and a gradient boron-doped diamond semiconductor layer arranged on the surface of the Ti-B compound gradient transition layer. The Ti-B compound gradient transition layer has a gradient increase of boron content from bottom to top. The gradient boron-doped diamond semiconductor layer has a gradient decrease of boron content from bottom to top. The application sets the Ti-B compound gradient transition layer on the surface of the titanium base, and then sets the gradient boron-doped diamond semiconductor layer on the surface of the transition layer, so that the prepared composite coating material has good film-base combination performance, high stability, excellent conductivity and electrochemical performance.

Description

Technical Field

[0001] This invention relates to a titanium-based boron-doped diamond semiconductor composite coating material, its preparation method, and its application, belonging to the field of materials preparation. Background Technology

[0002] Diamond possesses excellent physicochemical properties. Its hardness, molar density, thermal conductivity, sound velocity, and elastic modulus are the highest among known materials. It also exhibits good corrosion resistance, light transmittance, heat resistance, and radiation resistance. Pure diamond has a very high resistivity, making it an excellent electrical insulator. Doping diamond with boron atoms can transform it from an insulating material with a band gap of 5.47 eV into a semiconductor or even a conductor, greatly expanding its application range. At low doping levels, diamond exhibits semiconductor properties, with high electron / hole mobility, making it an ideal material for fabricating high-temperature semiconductors and radiation-resistant semiconductors. At high doping levels, diamond exhibits half-metallic conductivity, making it an ideal anolyte material for electrochemical synthesis, electrochemical oxidation, and electrochemical analysis.

[0003] Boron-doped diamond (BDD) coatings can be deposited on various substrates within a reasonable timescale and a controllable doping level using chemical vapor deposition (CVD) technology. The most commonly used metal substrates for depositing BDD coatings are Ti, Ta, and Nb. Among these, Ti is considered an ideal metal substrate for preparing BDD composite coating materials due to its low specific gravity, good corrosion resistance, and relatively low cost.

[0004] However, as a strong carbide-forming element, Ti strongly absorbs active C atoms during BDD (Bipolar Dioxide) deposition, which slows down BDD coating growth. Furthermore, Ti reacts with C to form the TiC phase, which easily leads to coating peeling during material service. Diamond has a coefficient of thermal expansion of 1.1 × 10⁻⁶. -6 K -1 The coefficient of thermal expansion of pure Ti is 10.03 × 10⁻⁶. -6 K -1 There is a significant thermal expansion mismatch between the two. These factors make it difficult to obtain a highly stable BDD coating on the Ti surface, thus limiting the industrial application of Ti-based BDD composite coating materials.

[0005] Without adding other elements, a Ti-B compound gradient transition layer is set on the surface of a Ti substrate, and then a gradient boron-doped diamond semiconductor layer is set on the surface of the transition layer. The resulting composite coating material effectively improves the problem of mismatch in thermal expansion coefficients, while reducing the solid solution absorption of active C atoms by Ti and the formation of TiC phase during the deposition stage, which greatly improves the stability of the Ti-based BDD semiconductor composite coating material. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the first objective of this invention is to provide a titanium-based boron-doped diamond semiconductor composite coating material that possesses both high adhesion and high stability in its composite coating.

[0007] The second objective of this invention is to provide a method for preparing a titanium-based boron-doped diamond semiconductor composite coating material.

[0008] The third objective of this invention is to provide an application of a titanium-based boron-doped diamond semiconductor composite coating material.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] This invention discloses a titanium-based boron-doped diamond semiconductor composite coating material, comprising a titanium substrate, a Ti-B compound gradient transition layer disposed on the surface of the titanium substrate, and a gradient boron-doped diamond semiconductor layer disposed on the surface of the Ti-B compound gradient transition layer. The boron content in the Ti-B compound gradient transition layer increases from bottom to top, while the boron content in the gradient boron-doped diamond semiconductor layer decreases from bottom to top.

[0011] This invention discloses a titanium-based boron-doped diamond semiconductor composite coating material, wherein the top of the Ti-B compound gradient transition layer is selected from at least one of Ti / TiB multiphase, TiB single phase, TiB2 single phase, Ti / TiB / TiB2 multiphase, and TiB / TiB2 multiphase.

[0012] In a further preferred embodiment, the top of the Ti-B compound gradient transition layer is selected from at least one of the Ti / TiB multiphase and TiB single phase.

[0013] In this invention, the Ti-B compound gradient transition layer provided by this invention has a boron content gradient that increases from bottom to top. The bottom layer has a lower B content, so the bottom layer preferentially forms the TiB phase. At a certain temperature, TiB can further combine with B to obtain TiB2. After preparation, the phase distribution from the interior to the surface of the natural matrix is ​​Ti-TiB or Ti-TiB-TiB2.

[0014] In this invention, the introduction of a Ti-B compound gradient transition layer serves two purposes. First, it reduces the absorption of active C atoms by Ti during the chemical vapor deposition of a gradient boron-doped diamond semiconductor layer, thus reducing the formation of the TiC phase. Second, both TiB and TiB2 in the transition layer are highly conductive phases with thermal expansion coefficients between those of diamond and pure titanium, creating a smooth transition between Ti and the BDD coating. The bottom layer of the transition layer has a lower boron content, which helps retain the mechanical properties and conductivity of the metal substrate. The top layer has a higher boron content to enhance the chemical bonding between the transition layer and the BDD coating, further improving the film-substrate adhesion. The intermediate layers employ a gradient increase in boron content, which helps alleviate the hardness gradient between the substrate and the transition layer, resulting in a natural transition between coatings, reducing the likelihood of separation and breakage, and improving adhesion.

[0015] This invention discloses a titanium-based boron-doped diamond semiconductor composite coating material, wherein the thickness of the Ti-B compound gradient transition layer is 5-100 μm. The inventors discovered that controlling the thickness of the transition layer within this range yields optimal performance. If the transition layer is too thin, the boron content in the transition layer is low, failing to effectively improve the chemical bonding with the gradient boron-doped diamond coating; if the transition layer is too thick, the bonding between the transition layer and the substrate becomes weak, resulting in brittleness and easy peeling.

[0016] This invention discloses a titanium-based boron-doped diamond semiconductor composite coating material. The gradient boron-doped diamond semiconductor layer comprises, from bottom to top, a boron-doped diamond bottom layer, a boron-doped diamond intermediate layer, and a boron-doped diamond top layer. The boron-doped diamond bottom layer has a uniform boron content, with a B / C ratio of 46,666-60,000 ppm (atomic ratio). The boron-doped diamond top layer also has a uniform boron content, with a B / C ratio of 26,666-40,000 ppm (atomic ratio). The boron content in the boron-doped diamond intermediate layer decreases linearly from bottom to top, with the boron content at the bottom layer being the maximum and decreasing linearly to the top layer.

[0017] In this invention, the boron-doped diamond bottom layer uses a uniform boron content to maximize the conductivity of the substrate, enhance the chemical bonding between the BDD coating and the Ti-B compound gradient transition layer, and further improve the film-substrate bonding performance. The boron-doped diamond top layer also uses a uniform boron content to maximize the corrosion resistance of the top layer, effectively reduce the coating peeling rate, and improve the service life of the material. The boron-doped diamond intermediate layer adopts a linearly decreasing boron gradient, which allows for a natural transition between coatings, making it less prone to separation and breakage, and improving the bonding strength.

[0018] In a further preferred embodiment, the boron-doped diamond bottom layer, the boron-doped diamond middle layer, and the boron-doped diamond top layer have equal thicknesses.

[0019] This invention discloses a titanium-based boron-doped diamond semiconductor composite coating material, wherein the gradient boron-doped diamond semiconductor layer is uniformly deposited on the surface of a Ti-B compound gradient transition layer by chemical vapor deposition, and the thickness of the gradient boron-doped diamond semiconductor layer is 1μm-2mm.

[0020] Specifically, a boron-doped diamond bottom layer, a boron-doped diamond intermediate layer, and a boron-doped diamond top layer are first deposited on the surface of the Ti-B compound gradient transition layer, and finally a boron-doped diamond top layer is deposited.

[0021] In this invention, the boron-doped diamond bottom layer, the boron-doped diamond middle layer, and the boron-doped diamond top layer all have the same thickness range.

[0022] This invention relates to a titanium-based boron-doped diamond semiconductor composite coating material, wherein the titanium in the titanium matrix is ​​selected from pure Ti or Ti alloys.

[0023] This invention relates to a titanium-based boron-doped diamond semiconductor composite coating material, wherein the structure of the titanium substrate is one of zero-dimensional, one-dimensional, two-dimensional, or three-dimensional.

[0024] This invention discloses a titanium-based boron-doped diamond semiconductor composite coating material, wherein the titanium substrate surface has a micro-nano structure.

[0025] In this invention, the fabrication method of the micro-nano structure is not limited, such as at least one of high-temperature atmosphere etching, high-temperature metal etching, and plasma etching.

[0026] The present invention discloses a titanium-based boron-doped diamond semiconductor composite coating material, wherein diamond particles are embedded in the titanium matrix, and the diamond particles have a diameter of 250-500 μm.

[0027] In this invention, embedding diamond particles as a matrix can promote the homogeneous epitaxial growth of the BDD coating, improve the adhesion between the BDD coating and the metal substrate, and reduce the interfacial resistance. In addition, compared with the flat metal substrate BDD semiconductor coating material, the exposed protrusions of the embedded diamond particles can expand the surface area of ​​the BDD coating, which helps to improve the current efficiency in the electrochemical oxidation process. More importantly, the inventors have found that when an appropriate amount of diamond particles are introduced, the gradient boron-doped diamond semiconductor layer grown on the metal substrate has the most obvious diamond phase and the (111) crystal plane preferred growth tendency, which further improves the performance of the semiconductor composite coating material.

[0028] In this invention, the particle size of the embedded diamond needs to be effectively controlled. If it is not within the scope of this invention, it will not only fail to be effectively embedded in the metal substrate, but the final composite material will also have poor performance.

[0029] In a further preferred embodiment, the diamond particles are distributed at a density of 5% to 60% on the titanium matrix.

[0030] If the diamond particle density is too low, it cannot provide enough nucleation sites for the homogeneous growth of BDD, and cannot effectively improve the diamond growth quality and film-matrix bonding performance; if the particle density is too high, the particles will squeeze each other, affecting the bonding force between the particles and the matrix, thereby further affecting the film-matrix bonding performance.

[0031] In a further preferred embodiment, the diamond particles are embedded in the titanium matrix at a depth of 100–350 μm.

[0032] The optimal performance is achieved by controlling the embedding depth of diamond particles in the titanium matrix within the aforementioned range. If the embedding depth is too shallow, the diamond particles will not be effectively embedded in the titanium matrix, which may cause a large number of particles to fall off. The low bonding strength between the diamond particles and the matrix will also easily cause the BDD film to collapse. If the embedding depth is too deep, the exposed area of ​​the diamond particles on the matrix will be small, which will not provide enough nucleation sites for the homogeneous growth of BDD.

[0033] In a further preferred embodiment, the diamond particles are embedded in a titanium matrix.

[0034] The inventors discovered that by embedding diamond particles onto a titanium substrate, most of the diamond particles are embedded on the surface of the titanium substrate; a small portion of the diamond particles detach 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 the formation of a dense and uniform diamond film with a large specific surface area, thereby enhancing the overall performance of the diamond electrode.

[0035] In a further preferred embodiment, the diamond particles are selected from pure diamond particles or boron-doped diamond particles, preferably boron-doped diamond particles.

[0036] This invention discloses a method for preparing a titanium-based boron-doped diamond semiconductor composite coating material. A Ti-B compound gradient transition layer is prepared on the surface of a titanium substrate, and then a gradient boron-doped diamond semiconductor layer is grown on the titanium substrate containing the Ti-B compound gradient transition layer by chemical vapor deposition to obtain a titanium-based boron-doped diamond semiconductor composite coating material.

[0037] In actual operation, a titanium substrate containing pure Ti or Ti alloy can be cleaned and degreased, and then a porous structure can be formed on the surface by acid etching, which can further improve the adhesion of the film substrate to the subsequent film formation. For example, the Ti substrate can be placed in a 3 mol / L hydrochloric acid solution, heated to 90°C, and kept at that temperature for 30 minutes.

[0038] In a preferred embodiment, diamond particles are first embedded in a titanium matrix to obtain a titanium matrix with embedded diamond particles, and then a Ti-B compound gradient transition layer is prepared on the surface of the titanium matrix with embedded diamond particles.

[0039] In actual operation, diamond particles are laid flat on the surface of the titanium matrix according to the designed distribution density of the embedded diamond particles, and then the diamond particles are embedded into the titanium matrix by mechanical pressing using a powder press.

[0040] In a further preferred embodiment, the pressing pressure is 10-20 kN. By controlling the pressure within the above range, the final pressing depth can be effectively controlled to be 100-350 μm.

[0041] In this invention, the preparation method of the Ti-B compound gradient transition layer is not limited, as long as the thickness and composition requirements of the transition layer can be met. For example, one of the existing technologies such as electroplating, vapor deposition, magnetron sputtering, chemical vapor deposition, and physical vapor deposition can be used.

[0042] In a preferred embodiment, a Ti-B compound gradient transition layer is prepared on the surface of a titanium substrate by magnetron sputtering or heat treatment.

[0043] The inventors discovered that when using the heat treatment method, since the penetration of boron is from the surface to the inside, a gradient transition layer of boron-doped Ti-B compound can be formed, in which the boron content increases from bottom to top. When using the magnetron sputtering method, the boron content in the Ti-B compound gradient transition layer can be adjusted by the sputtering power and the proportion of boron-containing atmosphere.

[0044] In a further preferred embodiment, when preparing the Ti-B compound gradient transition layer using magnetron sputtering, a Ti target or TiB target with a purity ≥99.99% is used, the distance between the titanium substrate and the target is 5-12 cm, the working pressure is 0.2-3 Pa, the sputtering power is 40-200 W, and the sputtering time is 5-100 min; the sputtering atmosphere is a B-containing atmosphere, preferably borane.

[0045] In a further preferred embodiment, when preparing the Ti-B compound gradient transition layer by heat treatment, the titanium substrate is placed in a B-rich atmosphere for heat treatment, or the titanium substrate is wrapped with B salt or solid B powder and then heat-treated in an argon atmosphere. The heat treatment temperature is controlled at 600-1200℃, preferably 600-1000℃, the heat treatment time is 1-20h, and the working pressure is 2-10kPa.

[0046] In a further preferred embodiment, the titanium substrate is coated with solid boron powder and then heat-treated under an argon atmosphere. When the heat treatment temperature is 700–900°C, the film-substrate bonding performance and degradation performance of BDD are optimal when the solid boron powder is used for boron doping through heat treatment is controlled within the above range. If the temperature is lower than this range, the chemical potential of boron atoms is low, the boron content at the top of the transition layer is low, and the formation of TiC phase cannot be effectively suppressed, thus failing to improve the film-substrate bonding performance. If the temperature is higher than this range, it is easy to cause phase transformation of the titanium substrate, increase the crystal porosity, and increase the thermal stress between the coating and the substrate.

[0047] However, when a transition layer is set within the temperature range of 600-1200℃ controlled by this invention, the performance of the resulting composite coating material is superior to that without a transition layer.

[0048] More preferably, the particle size of the solid B powder is ≤20μm.

[0049] The inventors discovered that by using a titanium substrate coated with high-purity ultrafine boron powder with a particle size of ≤20μm and controlling the heat treatment temperature within the aforementioned preferred range, the resulting transition layer has the best quality, and the performance of the resulting titanium-based boron-doped diamond semiconductor composite coating material is also the best.

[0050] In a further preferred embodiment, the titanium substrate containing the Ti-B compound gradient transition layer is etched in a non-oxidizing atmosphere at a temperature of 500-1100°C for 1-6 hours and a pressure of 8-25 kPa. This etching process forms micro / nano structures on the surface of the titanium substrate, further enhancing adhesion.

[0051] A preferred embodiment of the process for growing a gradient boron-doped diamond semiconductor layer on a titanium substrate containing a Ti-B compound gradient transition layer via chemical vapor deposition is as follows: First, the titanium substrate containing the Ti-B compound gradient transition layer is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment is performed, followed by drying; a titanium substrate with surface-adsorbed nanocrystalline and / or microcrystalline diamond is obtained. Then, the titanium substrate with surface-adsorbed nanocrystalline and / or microcrystalline diamond is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced to perform chemical vapor deposition to grow a gradient boron-doped diamond semiconductor layer. The temperature of the chemical vapor deposition is 600-1000℃, and the gas pressure is 10. 3 -10 4 Pa, time is 3-20h

[0052] In a further preferred embodiment, the suspension containing nanocrystalline and / or microcrystalline diamond mixed particles has a diamond mixed particle mass fraction of 0.01%-0.05%; the diamond mixed particles have a particle size of 5-30 nm and a purity of ≥97%; and the ultrasonic treatment time is 5-30 min.

[0053] In a further preferred embodiment, during the chemical vapor deposition, the percentage of carbon-containing gas in the total gas mass flow rate in the furnace is 0.5-10.0%, preferably 2-5%.

[0054] In a further preferred embodiment, during the chemical vapor deposition, the percentage of boron-containing gas in the total mass flow rate of the furnace is first controlled to be 0.069%-0.0884% to obtain a boron-doped diamond underlayer. Then, the boron doping concentration is reduced linearly until the percentage of boron-containing gas in the total mass flow rate of the furnace is 0.03968%-0.0593% to obtain a boron-doped diamond transition layer. Then, the percentage of boron-containing gas in the total mass flow rate of the furnace is controlled to be 0.03968%-0.0593% again to obtain a boron-doped diamond outer layer; thus, a gradient boron-doped diamond semiconductor layer is obtained.

[0055] The present invention also provides an application of a titanium-based boron-doped diamond semiconductor composite material, wherein the semiconductor composite coating material is applied to at least one of semiconductor devices, electrochemical oxidation, electrochemical synthesis, and electrochemical analysis.

[0056] Beneficial effects

[0057] This invention addresses the significant difference in thermal expansion coefficients between Ti and diamond, as well as the issue of low stability in Ti-based BDD semiconductor composite coating materials caused by the strong solid solution of titanium to activated carbon. It proposes a Ti-B compound gradient transition layer on the surface of a metallic titanium substrate, followed by a gradient boron-doped diamond semiconductor layer on the surface of the transition layer. This forms a Ti-Ti-B compound gradient transition layer-gradient boron-doped diamond semiconductor composite coating material configuration, significantly improving the film-substrate bonding performance and service stability of the Ti-based BDD semiconductor composite material, and reducing the risk of peeling off during the chemical vapor deposition cooling stage and subsequent service stages. Attached Figure Description

[0058] Figure 1 A schematic diagram of the process flow of this invention.

[0059] Figure 2 Electron micrographs of the cross-sections of the titanium-based boron-doped diamond semiconductor composite materials obtained in Comparative Example 1 and Examples 1-3. The images show that, under the same BDD growth process, the film-substrate interface of the sample without a transition layer is blurred, with obvious porous TiC phase formation; after heat treatment at 600℃ to add the transition layer, the film-substrate interface is clear, but a small amount of porous TiC phase can still be observed; as the temperature increases, the film-substrate interface becomes more distinct, the porous TiC phase gradually decreases, and the BDD coating thickness increases significantly.

[0060] Figure 3The XRD patterns obtained after preparing the Ti-B compound gradient transition layer on the surface of the titanium substrate in Examples 1-3 show that, since XRD detection has a certain depth, the phases detected here are not necessarily the phases at the top of the substrate, but all phases within a certain depth range. As can be seen from the figure, there are TiB peaks at 600℃ and 800℃; at 1000℃, both TiB and TiB2 peaks appear.

[0061] Figure 4 Lifetime test current-voltage characteristic curves of Example 1 and Comparative Example 1. Detailed Implementation

[0062] Example 1

[0063] A pure Ti matrix was encapsulated with 5μm solid boron powder and placed in a tube furnace under argon gas as a protective gas for heat treatment. The gas pressure was set to 3000 Pa, the heating temperature was 800℃, and the furnace was cooled after holding at that temperature for 2 hours. Figure 3 The TiB peak can be seen in the XRD (800℃) graph.

[0064] Then, a Ti substrate with a Ti-B compound gradient transition layer on its surface is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment is performed, followed by drying; a substrate material with nanocrystalline and / or microcrystalline diamond adsorbed on its surface is obtained; the mass fraction of the diamond mixture particles in the suspension containing nanocrystalline and / or microcrystalline diamond particles is 0.01%; the particle size of the diamond mixture particles is 10 nm, and the purity is ≥97%; the ultrasonic treatment time is 20 min.

[0065] A substrate material with surface-adsorbed nanocrystalline and / or microcrystalline diamond is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced. First, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.069% to obtain a boron-doped diamond bottom layer. Then, the boron doping concentration is reduced linearly until the percentage of boron-containing gas in the total gas flow rate in the furnace is 0.0493% to obtain a boron-doped diamond intermediate layer. Then, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.03968% to deposit a boron-doped diamond top layer. Thus, a gradient boron-doped diamond semiconductor layer is obtained.

[0066] The carbon-containing gas accounts for 3% of the total gas mass flow rate in the furnace, the boron-doped diamond deposition temperature is 700℃, and the gas pressure is 10. 3 The deposition time was 10 hours. The resulting titanium-based boron-doped diamond composite coating material exhibited good adhesion, with no peeling after removal from the furnace and no peeling after scratching.

[0067] Using the coating material as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 60 mA / cm². 2A degradation experiment was conducted using simulated dye wastewater (500 mL of 0.1 g / L RB-19 solution, 0.5 M sodium sulfate) as the research object. After 4 hours of degradation, the wastewater changed from deep blue to colorless and clear, with a color removal rate of 99% and an energy consumption of 1.8 kWh / m³ for color removal. 3 ·A -1 .

[0068] Using the coated electrode as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 1 A / cm². 2 An accelerated service life test was conducted in a 1 mol / L H₂SO₄ solution. After 180 hours of electrolysis, the cell voltage rapidly increased, and the electrode completely failed. The accelerated service life of this electrode, converted to an actual service life of 72,000 hours, demonstrates long stability and lifespan, making it suitable for industrial applications.

[0069] Example 2

[0070] Other conditions were the same as in Example 1, except that the pure Ti matrix was encapsulated with 5μm solid boron powder, placed in a tube furnace, and heat-treated with argon gas as a protective gas. The gas pressure was set to 3000 Pa, the heating temperature was 600℃, and the furnace was cooled after holding at that temperature for 2 hours. Figure 3 The TiB peak can be seen in the XRD (600℃) graph.

[0071] Using the coating material as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 60 mA / cm². 2 A degradation experiment was conducted using simulated dye wastewater (500 mL of 0.1 g / L RB-19 solution, 0.5 M sodium sulfate) as the research object. After 4 hours of degradation, the wastewater changed from deep blue to colorless and clear, with a color removal rate of 99% and an energy consumption of 1.9 kWh / m³ for color removal. 3 ·A -1 .

[0072] Using the coated electrode as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 1 A / cm². 2 An accelerated service life test was conducted in a 1 mol / L H₂SO₄ solution. After 150 hours of electrolysis, the cell voltage rapidly increased, and the electrode completely failed. The accelerated service life of this electrode, converted to an actual service life of 60,000 hours, demonstrates long stability and lifespan, making it suitable for industrial applications.

[0073] Example 3

[0074] Other conditions were the same as in Example 1, except that the pure Ti matrix was coated with 5μm solid boron powder, placed in a tube furnace, and heat-treated with argon gas as a protective gas. The gas pressure was set to 3000 Pa, the heating temperature was 1000℃, and the temperature was maintained for 2 hours before cooling with the furnace. Figure 3The XRD pattern (1000℃) shows the presence of both TiB and TiB2 peaks.

[0075] Using the coating material as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 60 mA / cm². 2 A degradation experiment was conducted using simulated dye wastewater (500 mL of 0.1 g / L RB-19 solution, 0.5 M sodium sulfate) as the research object. After 4 hours of degradation, the wastewater changed from deep blue to colorless and clear, with a color removal rate of 99% and an energy consumption of 1.8 kWh / m³ for color removal. 3 ·A -1 .

[0076] Using the coated electrode as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 1 A / cm². 2 An accelerated service life test was conducted in a 1 mol / L H₂SO₄ solution. After 150 hours of electrolysis, the cell voltage rapidly increased, and the electrode completely failed. The accelerated service life of this electrode, converted to an actual service life of 60,000 hours, demonstrates long stability and lifespan, making it suitable for industrial applications.

[0077] Example 4

[0078] Then, boron-doped diamond particles with a particle size of 300 μm were taken and mechanically embedded into the etched titanium substrate using a powder press. The embedding pressure was controlled at 15 kN to obtain a titanium substrate embedded with boron-doped diamond particles. The embedding depth of the boron-doped diamond particles was 100–150 μm, and the density of the boron-doped diamond particles was 40%.

[0079] The titanium substrate was then wrapped with solid boron powder and placed in a tube furnace with argon gas as a protective gas for heat treatment. The gas pressure was set at 3000 Pa, the heating temperature was between 800℃ and 300 Pa, and the substrate was held at that temperature for 2 hours before being cooled with the furnace.

[0080] Then, a Ti substrate with a Ti-B compound gradient transition layer on its surface is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment is performed, followed by drying; a substrate material with nanocrystalline and / or microcrystalline diamond adsorbed on its surface is obtained; the mass fraction of the diamond mixture particles in the suspension containing nanocrystalline and / or microcrystalline diamond particles is 0.01%; the particle size of the diamond mixture particles is 10 nm, and the purity is ≥97%; the ultrasonic treatment time is 20 min.

[0081] A substrate material with surface-adsorbed nanocrystalline and / or microcrystalline diamond is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced. First, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.069% to obtain a boron-doped diamond bottom layer. Then, the boron doping concentration is reduced linearly until the percentage of boron-containing gas in the total gas flow rate in the furnace is 0.0493% to obtain a boron-doped diamond intermediate layer. Then, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.03968% to deposit a boron-doped diamond top layer. Thus, a gradient boron-doped diamond semiconductor layer is obtained.

[0082] The carbon-containing gas accounts for 3% of the total gas mass flow rate in the furnace, the boron-doped diamond deposition temperature is 700℃, and the gas pressure is 10. 3 Pa, deposition time was 10h.

[0083] The obtained titanium-based boron-doped diamond composite coating material has good adhesion, no peeling after leaving the furnace, and no peeling after scratching. The Ti-B compound gradient transition layer is covered by the gradient boron-doped diamond film grown in a directional (111) pattern.

[0084] Using the coating material as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 60 mA / cm². 2 A degradation experiment was conducted using simulated dye wastewater (500 mL of 0.1 g / L RB-19 solution, 0.5 M sodium sulfate) as the research object. After 4 hours of degradation, the wastewater changed from deep blue to colorless and clear, with a color removal rate of 99% and an energy consumption of 1.6 kWh / m³ for color removal. 3 ·A -1 .

[0085] Using the coated electrode as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 1 A / cm². 2 An accelerated service life test was conducted in a 1 mol / L H₂SO₄ solution. After 220 hours of electrolysis, the cell voltage rapidly increased, and the electrode completely failed. The accelerated service life of this electrode, converted to an actual service life of 88,000 hours, demonstrates long stability and lifespan, making it suitable for industrial applications.

[0086] Comparative Example 1

[0087] All other conditions were the same as in Example 1, except that no Ti-B compound transition layer was prepared on the substrate. The resulting composite coating material experienced slight peeling after baking, with a unit colorimetric energy consumption of 2.2 kWh / m³. 3 ·A -1 The service life in the accelerated life test was 120 hours, and the electrode performance was significantly worse than that of Example 1.

Claims

1. A titanium-based boron-doped diamond semiconductor composite coating material, characterized in that: The titanium-based boron-doped diamond semiconductor composite coating material consists of a titanium substrate, a Ti-B compound gradient transition layer disposed on the surface of the titanium substrate, and a gradient boron-doped diamond semiconductor layer disposed on the surface of the Ti-B compound gradient transition layer. The boron content in the Ti-B compound gradient transition layer increases from bottom to top, while the boron content in the gradient boron-doped diamond semiconductor layer decreases from bottom to top. The titanium matrix is ​​embedded with boron-doped diamond particles, the particle size of which is 250~500μm. The boron-doped diamond particles have a distribution density of 5% to 60% on the titanium matrix. The boron-doped diamond particles are embedded in the titanium matrix at a depth of 100~350μm; The boron-doped diamond particles are embedded in a titanium matrix.

2. The titanium-based boron-doped diamond semiconductor composite coating material according to claim 1, characterized in that: The composition at the top of the Ti-B compound gradient transition layer is selected from at least one of Ti / TiB multiphase, TiB single phase, TiB2 single phase, Ti / TiB / TiB2 multiphase, and TiB / TiB2 multiphase; The thickness of the Ti-B compound gradient transition layer is 5-100 μm.

3. The titanium-based boron-doped diamond semiconductor composite coating material according to claim 1 or 2, characterized in that: The gradient boron-doped diamond semiconductor layer, from bottom to top, includes a boron-doped diamond bottom layer, a boron-doped diamond intermediate layer, and a boron-doped diamond top layer. The boron-doped diamond bottom layer has a uniform boron content, with a B / C ratio of 46,666-60,000 ppm on an atomic ratio basis. The boron-doped diamond top layer has a uniform boron content, with a B / C ratio of 26,666-40,000 ppm on an atomic ratio basis. The boron content in the boron-doped diamond intermediate layer decreases linearly from bottom to top, with the boron content in the boron-doped diamond bottom layer being the maximum value and decreasing linearly to the boron content in the boron-doped diamond top layer. The gradient boron-doped diamond semiconductor layer is uniformly deposited on the surface of the Ti-B compound gradient transition layer by chemical vapor deposition, and the thickness of the gradient boron-doped diamond semiconductor layer is 1μm-2mm.

4. The titanium-based boron-doped diamond semiconductor composite coating material according to claim 1 or 2, characterized in that: The titanium in the titanium matrix is ​​selected from pure Ti or Ti alloys; The structure of the titanium matrix is ​​one of zero-dimensional, one-dimensional, two-dimensional, or three-dimensional. The surface of the titanium substrate has a micro-nano structure.

5. A method for preparing a titanium-based boron-doped diamond semiconductor composite coating material according to any one of claims 1-4, characterized in that: A Ti-B compound gradient transition layer is prepared on the surface of a titanium substrate, and then a gradient boron-doped diamond semiconductor layer is grown on the titanium substrate containing the Ti-B compound gradient transition layer by chemical vapor deposition to obtain a titanium-based boron-doped diamond semiconductor composite coating material.

6. The method for preparing a titanium-based boron-doped diamond semiconductor composite coating material according to claim 5, characterized in that: Boron-doped diamond particles are first embedded in a titanium matrix to obtain a titanium matrix with embedded boron-doped diamond particles, and then a Ti-B compound gradient transition layer is prepared on the surface of the titanium matrix with embedded boron-doped diamond particles; the embedding pressure is 10-20 kN.

7. The method for preparing a titanium-based boron-doped diamond semiconductor composite coating material according to claim 5, characterized in that: Ti-B compound gradient transition layers were prepared on the surface of a titanium substrate by magnetron sputtering or heat treatment. When preparing the Ti-B compound gradient transition layer by magnetron sputtering, a Ti target or TiB target with a purity ≥99.99% is used, the distance between the titanium substrate and the target is 5-12 cm, the working pressure is 0.2-3 Pa, the sputtering power is 40-200 W, the sputtering time is 5-100 min, and the sputtering atmosphere is a boron-containing atmosphere. When preparing the Ti-B compound gradient transition layer by heat treatment, the titanium substrate is placed in a B-rich atmosphere for heat treatment, or the titanium substrate is wrapped with B salt or solid B powder and then heat treated in an argon atmosphere. The heat treatment temperature is controlled at 600-1200℃, the heat treatment time is 1-20h, and the working pressure is 2-10kPa.

8. The method for preparing a titanium-based boron-doped diamond semiconductor composite coating material according to claim 5, characterized in that: The titanium substrate containing the Ti-B compound gradient transition layer is etched in a non-oxidizing atmosphere at a temperature of 500-1100℃ for 1-6 hours and a pressure of 8-25 kPa.

9. The method for preparing a titanium-based boron-doped diamond semiconductor composite coating material according to claim 5, characterized in that: The process of gradient boron doping of a titanium substrate containing a Ti-B compound gradient transition layer via chemical vapor deposition is as follows: First, the titanium substrate containing the Ti-B compound gradient transition layer is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment and drying are performed to obtain a titanium substrate with surface adsorption of nanocrystalline and / or microcrystalline diamond. Then, the titanium substrate with surface adsorption of nanocrystalline and / or microcrystalline diamond is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced to perform chemical vapor deposition to grow a gradient boron-doped diamond semiconductor layer. The temperature of the chemical vapor deposition is 600-1000℃, and the gas pressure is 10. 3 -10 4 Pa, time is 3-20h; In the suspension containing nanocrystalline and / or microcrystalline diamond mixed particles, the mass fraction of the diamond mixed particles is 0.01%-0.05%; the particle size of the diamond mixed particles is 5-30 nm, and the purity is ≥97%; the ultrasonic treatment time is 5-30 min. During the chemical vapor deposition process, the percentage of carbon-containing gas in the total gas mass flow rate within the furnace is 0.5-10.0%. During the chemical vapor deposition process, the percentage of boron-containing gas in the total mass flow rate of the furnace is first controlled to be 0.069%-0.0884% to obtain a boron-doped diamond underlayer. Then, the boron doping concentration is reduced linearly until the percentage of boron-containing gas in the total mass flow rate of the furnace is 0.03968%-0.0593% to obtain a boron-doped diamond transition layer. Then, the percentage of boron-containing gas in the total mass flow rate of the furnace is controlled to be 0.03968%-0.0593% again to obtain a boron-doped diamond outer layer; thus, a gradient boron-doped diamond semiconductor layer is obtained.

10. The method for preparing a titanium-based boron-doped diamond semiconductor composite coating material according to claim 5, characterized in that: The semiconductor composite coating material is applied to at least one of semiconductor devices, electrochemical oxidation, electrochemical synthesis, and electrochemical analysis.

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