阅读说明：本技术 金刚石涂层的制备方法及其制得的金刚石涂层、刀具 (Preparation method of diamond coating, diamond coating prepared by preparation method and cutting tool ) 是由 唐永炳 王陶 黄磊 李星星 张文军 李振声 于 2018-09-07 设计创作，主要内容包括：本发明公开了一种金刚石涂层的制备方法及其制得的金刚石涂层、刀具,涉及金刚石薄膜技术领域。金刚石涂层的制备方法包括以下步骤：用纳米金刚石悬浮液在表面带正/负电荷的基体上进行植晶,并通过热丝化学气相沉积法生长金刚石,得到金刚石涂层；纳米金刚石悬浮液中纳米金刚石颗粒的带电性与基体表面所带电荷相反。本发明利用静电吸附植晶方式,使分散在溶液中的纳米金刚石颗粒吸附在基体结构件上,通过该方式能大大提高纳米金刚石颗粒在基体上的吸附密度,在基体表面高密度形核,生长后的金刚石涂层附着力强、使用寿命长,涂层粗糙度低、精度高。沉积该涂层的刀具切削寿命久、加工精度高。(The invention discloses a preparation method of a diamond coating, the diamond coating prepared by the preparation method, and a cutter, and relates to the technical field of diamond films. The preparation method of the diamond coating comprises the following steps: carrying out crystal planting on a substrate with positive/negative charges on the surface by using the nano diamond suspension, and growing diamond by a hot filament chemical vapor deposition method to obtain a diamond coating; the charge of the nanodiamond particles in the nanodiamond suspension is opposite to the charge of the substrate surface. The invention utilizes the electrostatic adsorption crystal planting mode to lead the nano-diamond particles dispersed in the solution to be adsorbed on the substrate structural member, and the adsorption density of the nano-diamond particles on the substrate can be greatly improved by the mode, the high-density nucleation is carried out on the surface of the substrate, and the grown diamond coating has strong adhesive force, long service life, low roughness of the coating and high precision. The cutter deposited with the coating has long cutting life and high processing precision.)

1. A preparation method of a diamond coating is characterized by comprising the following steps:

carrying out crystal planting on a substrate with positive/negative charges on the surface by using the nano diamond suspension to enable nano diamond particles dispersed in the suspension to be adsorbed on the substrate, and then growing diamond on the substrate adsorbed with the nano diamond particles by a hot wire chemical vapor deposition method to obtain a diamond coating;

the charge of the nanodiamond particles in the nanodiamond suspension is opposite to the charge of the substrate surface.

2. The method for preparing a diamond coating according to claim 1, wherein the nano-diamond suspension comprises nano-diamond powder, water and a quaternary ammonium salt type surfactant;

the mass concentration of the nano diamond powder in the nano diamond suspension is 0.005-0.5%, and the concentration of the quaternary ammonium salt surfactant in the nano diamond suspension is 10^-7-10^-4mol/L, and the pH value of the nano-diamond suspension is 2-8.

3. The method for producing a diamond coating according to claim 2, characterized in that said quaternary ammonium salt type surfactant comprises quaternary ammonium salt type surfactant having acyloxy group, preferably trimethyl ammonium halide having acyloxy group, preferably C1-C3 alkylacryloyloxy modified trimethyl ammonium halide, further preferably methacryloyloxyethyl trimethyl ammonium chloride.

4. A method of producing a diamond coating according to any of claims 1-3, characterized in that the substrate is subjected to a corrosion treatment and optionally a hydrogen plasma treatment, resulting in a substrate with a positive/negative charge on the surface;

preferably, the etching treatment comprises washing with an alkaline solution and then with an acidic solution;

preferably, every 50mLH in the alkaline solution₂O contains 3 to 7g K₃[Fe(CN)]₆And 3 to 7g of an alkali metal hydroxide; preferably, the acid solution comprises a mineral acid and H in a volume ratio of 1:5 to 15₂O₂。

5. A method of producing a diamond coating according to claim 4, characterized in that the substrate is cleaned first, then subjected to a corrosion treatment and optionally a hydrogen plasma treatment, and cleaned again to obtain a substrate having a positive/negative charge on the surface;

preferably, the washing and the second washing each independently comprise ultrasonic washing with water for 2-5min, followed by ultrasonic washing with a ketone or alcohol solvent for 5-10 min.

6. A method for producing a diamond coating according to any of claims 1 to 3, characterized in that the substrate is seeded by placing the substrate in a nanodiamond suspension for ultrasonic adsorption;

preferably, the ultrasonic time is 20-40min, and the ultrasonic power is 3000-.

7. A method of producing a diamond coating according to any of claims 1 to 3 wherein the process parameters for filament cvd diamond growth include: hydrogen, methane and optional inert gas are used as reaction gases, the total flow of the reaction gases is 500-850sccm, wherein the flow of the methane gas accounts for 1-5% of the total flow, the flow of the hydrogen and optional inert gas accounts for 95-99% of the total flow, the deposition pressure is 1500-2000Pa, the filament power is 6500-7000W, the filament pitch is 7-15mm, and the deposition time is 1-3 h.

8. A method of producing a diamond coating according to any of claims 1 to 3, characterized by the steps of:

(a) ultrasonically cleaning the matrix for 2-5min by using water, and ultrasonically cleaning for 5-10min by using a ketone or alcohol solvent;

(b) carrying out corrosion treatment on the cleaned substrate, wherein the corrosion treatment comprises cleaning with an alkali solution and then cleaning with an acid solution; every 50mLH of alkali solution₂O contains 3 to 7g K₃[Fe(CN)]₆And 3-7g KOH; the acid solution comprises H with the volume ratio of 1:5-15₂SO₄And H₂O₂；

(c) Ultrasonically cleaning the corroded substrate for 2-5min by using water, and ultrasonically cleaning the corroded substrate for 5-10min by using a ketone or alcohol solvent;

(d) carrying out ultrasonic treatment and separation on the nano-diamond suspension to obtain a diamond dispersion liquid with the particle size of less than 10 nm; the ultrasonic time is 10-15min, the separation rotating speed is 5000-; the nano-diamond suspension comprises nano-diamond powder, water and methacryloyloxyethyl trimethyl ammonium chloride; the mass concentration of the nano diamond powder in the nano diamond suspension is 0.005-0.5%, and the concentration of the methacryloyloxyethyl trimethyl ammonium chloride in the nano diamond suspension is 10^-7-10^-4mol/L, the pH value of the nano-diamond suspension is 2-8;

(e) putting the matrix into the centrifuged diamond dispersion liquid for ultrasonic adsorption; the ultrasonic time is 20-40min, and the ultrasonic power is 3000 and 4000W;

(f) and placing the absorbed matrix in hot wire chemical vapor deposition equipment to grow a nano diamond film to obtain the diamond coating.

9. A diamond coating produced by the method for producing a diamond coating according to any one of claims 1 to 8.

10. A tool, characterized in that the tool surface is provided with a diamond coating according to claim 9.

Technical Field

The invention relates to the technical field of diamond films, in particular to a preparation method of a diamond coating and the diamond coating and a cutter prepared by the preparation method.

Background

With the rapid development of industry, light-weight and high-strength materials gradually become mainstream, new materials such as nonferrous metals, alloys, glass fiber reinforced plastics, graphite, ceramics and the like are widely applied in industry, and common high-speed steel and hard alloy cutters are difficult to be competent for mechanical cutting processing of the materials. Meanwhile, with the successive advent of modern integrated system machining centers, flow machine workshops, and computer integrated manufacturing systems, machining is being developed toward high precision, high speed, and high productivity machining, and various performances of the cutting tools are also required to be quite high. Therefore, there is a trend toward the development of superhard cutting tools having excellent cutting performance.

The diamond has the advantages of extremely stable physical and chemical properties, high hardness and wear resistance, good thermal conductivity, low friction coefficient and the like, can solve the problems of processing and processing precision of materials difficult to process, and has long service life. However, it is difficult to utilize the above excellent properties of diamond due to the rare amount, high price, limited size, etc. of natural diamond. The diamond film is grown on the surface of the cutting tool by adopting the hot wire assisted chemical vapor deposition technology, so that the service life of the cutting tool can be greatly prolonged, the machining precision of the tool is greatly improved, and the cutting tool is not limited by the size and the shape of the tool.

The hot filament chemical vapor deposition technology has the advantages of simple equipment, high film forming speed, convenient operation, low cost and the like. However, the temperature required by hot wire chemical vapor deposition is high, and after the diamond film is prepared by using the method, in the process of cooling to room temperature, because the difference between the thermal expansion coefficients of the diamond film and the hard alloy cutter is large, poor film-substrate interface bonding force caused by thermal stress is easily generated, cracks are formed on the interface, and the diamond film is easy to fall off in the cutting process. The ratio of the failure of the diamond film caused by the falling off of the diamond film to the service life termination of the cutter caused by abrasion in the cutting process is about 10:1, and the adhesion between the film and the cutter seriously influences the service life of the cutter.

Disclosure of Invention

It is an object of the present invention to provide a method for producing a diamond coating layer that solves at least one of the above problems.

The invention also aims to provide the diamond coating which is prepared by the preparation method of the diamond coating and has the advantages of good adhesive force, long service life, low roughness and high precision.

It is a further object of the present invention to provide a cutting tool having a surface provided with the diamond coating described above, with the same advantages as the coating described above.

In order to achieve the above purpose of the present invention, the following technical solutions are adopted:

in a first aspect, a method for preparing a diamond coating is provided, comprising the following steps:

carrying out crystal planting on a substrate with positive/negative charges on the surface by using the nano diamond suspension to enable nano diamond particles dispersed in the suspension to be adsorbed on the substrate, and then growing diamond on the substrate adsorbed with the nano diamond particles by a hot wire chemical vapor deposition method to obtain a diamond coating;

the charge of the nanodiamond particles in the nanodiamond suspension is opposite to the charge of the substrate surface.

Preferably, on the basis of the technical scheme of the invention, the nano-diamond suspension comprises nano-diamond powder, water and a quaternary ammonium salt type surfactant;

the mass concentration of the nano diamond powder in the nano diamond suspension is 0.005-0.5%, and the concentration of the quaternary ammonium salt surfactant in the nano diamond suspension is 10^-7-10^-4mol/L, and the pH value of the nano-diamond suspension is 2-8.

Preferably, on the basis of the technical scheme of the invention, the quaternary ammonium salt surfactant comprises a quaternary ammonium salt surfactant with acyloxy, preferably trimethyl ammonium halide with acyloxy, preferably C1-C3 alkyl acryloxy modified trimethyl ammonium halide, and further preferably methacryloxyethyl trimethyl ammonium chloride.

Preferably, on the basis of the technical scheme of the invention, the substrate is subjected to corrosion treatment and optional hydrogen plasma treatment to obtain the substrate with positive/negative charges on the surface;

preferably, the etching treatment comprises washing with an alkaline solution and then with an acidic solution;

preferably, every 50mLH in the alkaline solution₂O contains 3 to 7g K₃[Fe(CN)]₆And 3 to 7g of an alkali metal hydroxide; preferably, the acid solution comprises a mineral acid and H in a volume ratio of 1:5 to 15₂O₂。

Preferably, on the basis of the technical scheme of the invention, the substrate is cleaned firstly, then is subjected to corrosion treatment and optional hydrogen plasma treatment, and is cleaned again to obtain the substrate with positive/negative charges on the surface;

preferably, the washing and the second washing each independently comprise ultrasonic washing with water for 2-5min, followed by ultrasonic washing with a ketone or alcohol solvent for 5-10 min.

Preferably, on the basis of the technical scheme of the invention, the crystal planting mode is that the substrate is placed in the nano-diamond suspension for ultrasonic adsorption;

preferably, the ultrasonic time is 20-40min, and the ultrasonic power is 3000-.

Preferably, on the basis of the technical scheme of the invention, the process parameters for growing the diamond by the hot wire chemical vapor deposition method comprise: hydrogen, methane and optional inert gas are used as reaction gases, the total flow of the reaction gases is 500-850sccm, wherein the flow of the methane gas accounts for 1-5% of the total flow, the flow of the hydrogen and optional inert gas accounts for 95-99% of the total flow, the deposition pressure is 1500-2000Pa, the filament power is 6500-7000W, the filament pitch is 7-15mm, and the deposition time is 1-3 h.

Preferably, on the basis of the technical scheme of the invention, the preparation method of the diamond coating comprises the following steps:

(a) ultrasonically cleaning the matrix for 2-5min by using water, and ultrasonically cleaning for 5-10min by using a ketone or alcohol solvent;

(b) carrying out corrosion treatment on the cleaned substrate, wherein the corrosion treatment comprises cleaning with an alkali solution and then cleaning with an acid solution; every 50mLH of alkali solution₂O contains 3 to 7g K₃[Fe(CN)]₆And 3-7g KOH; the acid solution comprises 1:5 by volumeH of-15₂SO₄And H₂O₂；

(c) Ultrasonically cleaning the corroded substrate for 2-5min by using water, and ultrasonically cleaning the corroded substrate for 5-10min by using a ketone or alcohol solvent;

(d) carrying out ultrasonic treatment and separation on the nano-diamond suspension to obtain a diamond dispersion liquid with the particle size of less than 10 nm; the ultrasonic time is 10-15min, the separation rotating speed is 5000-; the nano-diamond suspension comprises nano-diamond powder, water and methacryloyloxyethyl trimethyl ammonium chloride; the mass concentration of the nano diamond powder in the nano diamond suspension is 0.005-0.5%, and the concentration of the methacryloyloxyethyl trimethyl ammonium chloride in the nano diamond suspension is 10^-7-10^-4mol/L, the pH value of the nano-diamond suspension is 2-8;

(e) putting the matrix into the centrifuged diamond dispersion liquid for ultrasonic adsorption; the ultrasonic time is 20-40min, and the ultrasonic power is 3000 and 4000W;

(f) and placing the absorbed matrix in hot wire chemical vapor deposition equipment to grow a nano diamond film to obtain the diamond coating.

In a second aspect, a diamond coating is provided, which is prepared by the preparation method of the diamond coating.

In a third aspect, a tool is provided, the tool surface being provided with the diamond coating described above.

Compared with the prior art, the invention has the following beneficial effects:

(1) the preparation method of the diamond coating of the invention makes the nano diamond particles dispersed in the suspension adsorbed on the substrate structure by utilizing the electrostatic adsorption crystal planting mode of the substrate with positive/negative charges and the nano diamond particles with the electric property opposite to that of the substrate, and the surface of the substrate is made to be negatively charged by using a method such as surface modification, so that the potential of the nano diamond particles is adjusted to be positive, or the surface of the substrate is positively charged, and the potential of the nano diamond particles is adjusted to be negative, and the two methods with positive and negative charges can realize the adsorption of the nano diamond particles on the substrate. The method can greatly improve the adsorption density of the nano diamond particles on the substrate and carry out high-density nucleation on the surface of the substrate, so that the grown diamond coating has strong adhesive force, long service life, low roughness and high precision. The cutter deposited with the coating has long cutting life and high processing precision.

In addition, the preferable typical embodiment of the invention is that the substrate is subjected to alkali-first acid-second corrosion treatment by using a specific solution to ensure that the surface of the substrate is negatively charged, the roughness of the substrate is increased, the nano-diamond suspension takes methacryloyloxyethyl trimethyl ammonium chloride as a dispersing agent, the nano-diamond particles are stably dispersed in the solution, the dispersed particle size is less than 10nm, the Zeta potential of the surface of the nano-diamond particles can be controlled by adjusting the concentration of the nano-diamond and the dispersing agent and the pH value of the dispersing solution to ensure that the surface of the nano-diamond particles is positively charged, and the adsorption density of the nano-diamond particles is very high by electrostatic adsorption under the system and reaches 2.5 multiplied by 10¹¹(nuclei/cm²) The diamond coating prepared by the method has extremely low friction coefficient and high precision, the binding force reaches the highest grade HF1 of the binding force of the industrial standard, and the service life is long.

(2) The coating deposition of the invention needs no intermediate layer, is deposited in place in one step, has simple preparation process and stable process, and is suitable for industrial production.

Drawings

FIG. 1 is a Rockwell indentation BSE topography of example 1;

FIG. 2 is the morphology of the Rockwell indentation BSE of example 2;

FIG. 3 is the morphology of the Rockwell indentation BSE of example 3;

FIG. 4 is the morphology of the Rockwell indentation BSE of example 4;

FIG. 5 is a BSE topography of the sample surface after cutting the sample with the tool of example 1;

fig. 6 is a BSE topography of the sample surface after cutting the sample with the cutter of comparative example 1.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

According to a first aspect of the present invention, there is provided a method of producing a diamond coating comprising the steps of: carrying out crystal planting on a substrate with positive/negative charges on the surface by using the nano diamond suspension to enable nano diamond particles dispersed in the suspension to be adsorbed on the substrate, and then growing diamond on the substrate adsorbed with the nano diamond particles by a hot wire chemical vapor deposition method to obtain a diamond coating; the charge of the nanodiamond particles in the nanodiamond suspension is opposite to the charge of the substrate surface.

The type and material of the substrate are not limited, and typically but not limited to, cutting tools (including but not limited to cemented carbide cutters, etc.), metal mesh (including but not limited to copper mesh, titanium mesh, stainless steel mesh, etc.) or fabric mesh, for example.

The surface of the substrate of the present invention is negatively/positively charged, and "/" in the positive/negative indicates the meaning of "or", i.e., the surface of the substrate is positively or negatively charged.

The manner of obtaining positive/negative charges on the surface of the substrate is not limited, and the manner of obtaining negative charges on the surface of the substrate is typically, but not limited to, subjecting the substrate to an etching treatment (e.g., an acid treatment); the manner in which the surface of the substrate acquires a positive charge is typically, but not by way of limitation, for example, by subjecting the substrate to a hydrogen plasma treatment.

The invention utilizes a hot wire chemical vapor deposition method to prepare the diamond film, the hot wire chemical vapor deposition method (hot wire CVD) is one of chemical vapor deposition methods, the hot wire chemical vapor deposition method is not limited, the method can be carried out by adopting a conventional hot wire chemical vapor deposition device and/or process, and can be a common hot wire method or other improved hot wire methods such as electronic assistance. The chemical vapor deposition diamond growth needs to implant diamond seed crystals, the diamond seed crystals are adsorbed on a substrate, and then epitaxial growth is carried out on the implanted seed crystal points to form the diamond film.

And implanting diamond seed crystals by using a nano-diamond suspension, wherein the nano-diamond suspension is a suspension mainly composed of nano-diamond particles. The charge property of the nano-diamond particles in the nano-diamond suspension is opposite to that of the substrate surface, namely when the substrate surface is positively charged, the nano-diamond particles in the suspension are negatively charged, and when the substrate surface is negatively charged, the nano-diamond particles in the suspension are positively charged.

The way of charging the nano-diamond particles in the suspension with positive or negative electricity is not limited, but a typical but non-limiting way is to add a surfactant into the suspension and modify the surface of the suspension to obtain corresponding charges.

The method of seeding is not limited, and the preferred method of seeding is to place the substrate in a diamond suspension for ultrasonic adsorption.

At present, in order to improve the adhesive force between a hard alloy substrate and a diamond film, a more common method is a method for preparing a gradient intermediate layer, and a plurality of layers of films are deposited between the substrate and a diamond coating, so that the effect of relieving thermal stress can be achieved. The method of adding the gradient intermediate layer not only greatly increases the preparation cost, but also has defects among the multilayer films, and the defects can be expanded during the use process of a cutter, for example, and finally cause the failure of the coating, so that the service life of the coating is short.

The preparation method of the diamond coating enables the nano diamond particles dispersed in the solution to be adsorbed on a substrate structural member by utilizing the electrostatic adsorption crystal planting mode of a substrate with positive/negative charges and nano diamond particles with the electric property opposite to that of the substrate, enables the surface of the substrate to be negatively charged by a surface modification method, adjusts the potential of the nano diamond particles to be positive, or enables the surface of the substrate to be positively charged, adjusts the potential of the nano diamond particles to be negative, and can realize the adsorption of the nano diamond particles on the substrate such as a complex three-dimensional hard alloy structural member. The method can greatly improve the adsorption density of the nano diamond particles on the substrate, and the nano diamond particles are subjected to high-density nucleation on the surface of the substrate, so that the grown diamond coating has strong adhesive force, long service life, low roughness and high precision.

In addition, the coating is deposited without an intermediate layer, is deposited in place in one step, has simple preparation process and stable process, and is suitable for industrial production.

In a preferred embodiment, the nanodiamond suspension comprises nanodiamond powder, water and a dispersing agent; the dispersant is preferably quaternary ammonium salt surfactant, the mass concentration of the nano-diamond powder in the nano-diamond suspension is 0.005-0.5%, and the concentration of the quaternary ammonium salt surfactant in the nano-diamond suspension is 10^-7-10^-4mol/L, and the pH value of the nano-diamond suspension is 2-8.

The nano-diamond powder is preferably detonation nano-diamond powder.

The quaternary ammonium salt surfactant is composed of ammonium cation [ H ]₄N⁺]The cationic surfactant in which all four hydrogen atoms are substituted by organic groups includes, but is not limited to, quaternary ammonium salts having alkyl groups, quaternary ammonium salts containing hetero atoms, quaternary ammonium salts containing benzene rings, hybrid quaternary ammonium salts, and the like. Quaternary ammonium salts having an acyloxy group are preferred.

Preferably, the quaternary ammonium salt is a trimethyl ammonium halide (e.g., trimethyl ammonium chloride, trimethyl ammonium bromide, or trimethyl ammonium iodide) having a modifying group, preferably a trimethyl ammonium halide having an acyloxy group.

Trimethyl ammonium halides having an acyloxy group include, but are not limited to, trimethyl ammonium chloride having an acyloxy group, trimethyl ammonium bromide having an acyloxy group, or trimethyl ammonium iodide having an acyloxy group. Preferably a C1-C3 alkylacryloxy modified trimethylammonium halide, preferably methacryloyloxyethyltrimethylammonium chloride (DMC).

The mass concentration of the nanodiamond powder in the nanodiamond suspension is, for example, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%; the concentration of trimethyl ammonium halide or its derivatives in the nanodiamond suspension is, for example, 10^-7mol/L、10^-6mol/L、10^-5mol/L or 10^-4mol/L; sodium (A)The pH of the rice diamond suspension is, for example, pH2, pH3, pH4, pH5, pH6, pH7, or pH 8.

Preferably, methacryloyloxyethyl trimethyl ammonium chloride is used as a dispersing agent for dispersing the nano diamond powder in the nano diamond suspension, so that the problems of agglomeration and sedimentation of the nano diamond powder in an aqueous solution are solved, the nano diamond particles can be stably dispersed in the solution, and the dispersion particle size is less than 10 nanometers; the Zeta potential of the nano diamond particles is improved by adjusting the concentration and the pH value of the dispersing agent, so that the stability of a dispersing solution is improved, the adsorption capacity of the nano diamond particles on a matrix is enhanced, and the adsorption density of the nano diamond particles on the surface of the hard alloy matrix reaches 2.5 multiplied by 10¹¹nuclei/cm²The prepared nano-diamond film has stronger bonding force (longer service life), lower roughness and friction coefficient (higher precision).

In a preferred embodiment, the substrate is subjected to an etching treatment and optionally a hydrogen plasma treatment, resulting in a substrate with a positively/negatively charged surface;

preferably, the etching treatment comprises washing with an alkaline solution and then with an acidic solution;

preferably, every 50mLH in the alkaline solution₂O contains 3 to 7g K₃[Fe(CN)]₆And 3 to 7g of an alkali metal hydroxide; preferably, the acid solution comprises a mineral acid and H in a volume ratio of 1:5 to 15₂O₂。

Alkali metal hydroxides include, but are not limited to, NaOH or KOH, preferably KOH. Inorganic acids include but are not limited to HCl, H₂SO₄Or HNO₃Is preferably H₂SO₄。

The basic solution contains, for example, 3g, 4g, 5g, 6g or 7g of K per 50mL of water₃[Fe(CN)]₆And, for example, 3g, 4g, 5g, 6g, or 7g of an alkali metal hydroxide. The acid solution comprises a mineral acid and H in a volume ratio of, for example, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, or 1:15₂O₂。

Preferably, the treatment mode of firstly carrying out alkali and then carrying out acid can be used for removing Co from the substrate on one hand and increasing the roughness of the substrate on the other hand, so that the diamond coating and the substrate have the mechanical occlusion effect, and the surface of the treated substrate is negatively charged.

Optionally, a hydrogen plasma treatment is performed to positively charge the surface of the treated substrate.

Preferably, the substrate is cleaned, then is subjected to corrosion treatment and optional hydrogen plasma treatment, and is cleaned again to obtain the substrate with positive/negative charges on the surface;

preferably, the washing and the second washing each independently comprise ultrasonic washing with water for 2-5min, followed by ultrasonic washing with a ketone or alcohol solvent for 5-10 min.

The ketone is preferably acetone, and the alcohol is preferably ethanol (ethanol).

Preferably, the cleaning comprises ultrasonic cleaning with water for 1-3 times, each for 2-5min, and ultrasonic cleaning with alcohol for 1-2 times, each for 5-10 min.

And cleaning the surface of the substrate, removing impurities on the surface of the substrate, and keeping the surface of the substrate clean. And cleaning after the corrosion treatment, and cleaning the residual corrosion solution in the matrix.

In a preferred embodiment, the process parameters for growing diamond by hot wire chemical vapor deposition include: hydrogen, methane and optionally inert gas are used as the reactant gas, the total reactant gas flow is 500-850sccm, such as 500sccm, 600sccm, 700sccm, 800sccm or 850sccm, wherein the methane gas flow is 1-5%, such as 1%, 2%, 3%, 4% or 5%, and the hydrogen and optionally inert gas flow is 95-99%, such as 99%, 98%, 97%, 96% or 95%, of the total flow; the deposition pressure is 1500-2000Pa, such as 1500Pa, 1600Pa, 1700Pa, 1800Pa, 1900Pa or 2000Pa, the filament power is 6500-7000W, such as 6500W, 6800W or 7000W, the filament sample distance (the sample distance of the upper and lower hot filaments) is 7-15mm, such as 7mm, 8mm, 9mm, 10mm, 12mm, 14mm or 15mm, and the deposition time is 1-3h, such as 1h, 2h or 3 h; graphite is preferably used as the water cooling table.

And the growth quality of the diamond coating is ensured by controlling the parameters of the deposition process.

As a preferred embodiment, a method for preparing a typical diamond coating includes the steps of:

(a) ultrasonically cleaning the matrix for 2-5min by using water, and ultrasonically cleaning for 5-10min by using a ketone or alcohol solvent;

(b) carrying out corrosion treatment on the cleaned substrate, wherein the corrosion treatment comprises cleaning with an alkali solution and then cleaning with an acid solution; every 50mLH of alkali solution₂O contains 3 to 7g K₃[Fe(CN)]₆And 3-7g KOH; the acid solution comprises H with the volume ratio of 1:5-15₂SO₄And H₂O₂；

(c) Ultrasonically cleaning the corroded substrate for 2-5min by using water, and ultrasonically cleaning the corroded substrate for 5-10min by using a ketone or alcohol solvent;

(d) carrying out ultrasonic treatment and separation on the nano-diamond suspension to obtain a diamond dispersion liquid with the particle size of less than 10 nm; the ultrasonic time is 10-15min, the separation rotating speed is 5000-; the nano-diamond suspension comprises nano-diamond powder, water and methacryloyloxyethyl trimethyl ammonium chloride; the mass concentration of the nano diamond powder in the nano diamond suspension is 0.005-0.5%, and the concentration of the methacryloyloxyethyl trimethyl ammonium chloride in the nano diamond suspension is 10^-7-10^-4mol/L, the pH value of the nano-diamond suspension is 2-8;

(e) putting the matrix into the centrifuged diamond dispersion liquid for ultrasonic adsorption; the ultrasonic time is 20-40min, and the ultrasonic power is 3000 and 4000W;

(f) and placing the absorbed matrix in hot wire chemical vapor deposition equipment to grow a nano diamond film to obtain the diamond coating.

Preferably, the process parameters of step (f) include: hydrogen, methane and optional inert gas are used as reaction gases, the total flow of the reaction gases is 500-850sccm, wherein the flow of the methane gas accounts for 1-5% of the total flow, the flow of the hydrogen and optional inert gas accounts for 95-99% of the total flow, the deposition pressure is 1500-2000Pa, the filament power is 6500-7000W, the filament pitch is 7-15mm, and the deposition time is 1-3 h.

The typical method is that the substrate is subjected to alkali-first acid-second corrosion treatment by using a specific solution and then the substrate is subjected toThe surface is negatively charged, the roughness of the matrix is increased, methacryloyloxyethyl trimethyl ammonium chloride is used as a dispersing agent in the nano-diamond suspension, nano-diamond particles are stably dispersed in the solution, the dispersion particle size is less than 10nm, the Zeta potential on the surface of the nano-diamond particles can be controlled by adjusting the concentration of the nano-diamond and the dispersing agent and the pH value of the dispersion liquid, so that the surface of the nano-diamond particles is positively charged, the adsorption density of the implanted crystals by electrostatic adsorption under the system is very high and reaches 2.5 multiplied by 10¹¹(nuclei/cm²) The diamond coating prepared by the method has extremely low friction coefficient and high precision, the binding force reaches the highest grade HF1 of the binding force of the industrial standard, and the service life is long.

According to a second aspect of the present invention, there is provided a diamond coating produced by the above method of producing a diamond coating.

The diamond coating prepared by the method has the advantages of good adhesive force, long service life, low roughness of the coating and high precision.

According to a third aspect of the invention, there is provided a tool, the tool surface being provided with a diamond coating as described above.

Due to the advantages of the diamond coating, the cutter with the coating has the advantages of long cutting life and high machining precision.

The invention is further illustrated by the following specific examples and comparative examples, but it should be understood that these examples are for purposes of illustration only and are not to be construed as limiting the invention in any way. All the raw materials related to the invention can be obtained commercially.