CN105801171A - Preparation method for diamond with controllable surface coating thickness, and product prepared by using the same - Google Patents

Abstract

The present invention relates to a method for preparing a diamond with a controlled thickness of the surface coating, the method comprising the following steps: (1) providing a diamond D with a surface coating, wherein the diamond D of the surface coating includes diamond and bonded to the The surface coating C on the diamond surface; (2) carrying out high-temperature treatment to the diamond D of the surface coating so that microcracks or micro-damages occur in the coating; (3) the diamond D of the surface coating processed through step (2) Exfoliation treatment is carried out to obtain a diamond with a thinned surface coating. The invention also discloses the products prepared by the method. The method has simple processing equipment and simple and rapid preparation process.

Description

A method for preparing diamond with controlled surface coating thickness and products obtained by using the method

technical field

The invention relates to the field of diamond composite materials, in particular to a method for controlling the thickness of a diamond surface coating and a product obtained by using the method.

Background technique

At present, when diamond tools are used in the mechanical tool market and the heat-conducting composite material market, due to the low bonding strength between diamond and metal or hard alloy substrates, it is often necessary to coat the diamond surface with a compound layer or alloy layer. In this In the process, the control of coating thickness is particularly important in some high-end applications.

For example, in the preparation process of diamond-metal heat-conducting composite materials, in order to improve the bonding strength between diamond and metal, a strong carbide element layer is often introduced between diamond and metal. The existing relatively excellent process is to coat the surface of diamond powder, but the high thickness of the coating will lead to a large interface thermal resistance between the diamond and the metal, which will affect the thermal conductivity of the composite material. control.

For example, in the process of preparing the diamond grinding wheel after the surface coating of the diamond powder, it is also necessary to control the thickness of the diamond surface coating. Too thick diamond surface coating will reduce the bonding strength with diamond or substrate due to external influences, and too thick diamond surface coating will affect subsequent process factors such as electroplating. Therefore, the control of the coating thickness on the surface of diamond powder has become a major constraint factor in the preparation of precision tools.

In the existing technology, the thickness of the diamond surface coating is often controlled by improving the process of the diamond surface coating process. This technical means often takes a lot of time and cost to meet the requirements.

To sum up, there is an urgent need to develop a method for controlling the thickness of the diamond surface coating with simple process and low cost in the above two fields.

Contents of the invention

The object of the present invention is to provide a method for controlling the thickness of the diamond surface coating with simple processing equipment and simple and rapid preparation process.

In a first aspect of the present invention, a method for preparing a diamond with a controlled surface coating thickness is provided, comprising the steps of:

(1) provide the diamond D of a surface coating, wherein, the diamond D of the surface coating comprises diamond and is bonded to the surface coating C of the described diamond surface; The surface coating C comprises the first coating C1 and the second coating C2; The first coating C1 is located between the diamond and the second coating C2;

The first coating layer C1 is a carbide layer selected from the group consisting of tungsten carbide, chromium carbide, molybdenum carbide, titanium carbide, or combinations thereof;

The second coating C2 is a carbide element layer or an alloy layer thereof, selected from the group consisting of tungsten, chromium, molybdenum, titanium, or a combination thereof;

The thickness of the first coating layer C1 is c1, and the thickness of the second coating layer C2 is c2;

(2) Carrying out high-temperature treatment to the diamond D of the surface coating, so that cracks appear in the second coating C2;

(3) Carrying out the diamond of the described surface coating of step (2) high-temperature treatment, falling off the second coating C2 to the target thickness c2', and obtaining a diamond D' with a reduced thickness of the surface coating, wherein 0≤ c2'<c2.

In another preferred example, the second plating layer is partially or completely peeled off.

In another preferred example, the high-temperature treatment includes the following steps: placing the surface-coated diamond D in a reaction furnace with a treatment temperature of 200-1500° C. and a non-oxidizing atmosphere.

In another preferred example, the treatment temperature is preferably 300-1000°C, more preferably 650-850°C.

In another preferred example, after the diamond D coated on the surface is placed in the reaction furnace at room temperature, the reaction furnace is heated to the processing temperature.

In another preferred example, the heating rate is 5-100°C/min, preferably 5-50°C/min, more preferably 5-20°C/min.

In another preferred example, the diamond D on the surface coating is kept at the treatment temperature.

In another preferred example, the holding time is 1-200 minutes, preferably 1-120 minutes, more preferably 5-120 minutes.

In another preferred example, the surface-coated diamond D is cooled after heat preservation treatment.

In another preferred example, the cooling rate is 5-100°C/min, preferably 5-50°C/min, more preferably 5-20°C/min.

In another preferred example, the reaction furnace cools down naturally after reaching the holding time.

In another preferred example, the surface coating C completely covers the diamond.

In another preferred embodiment, the non-oxidizing atmosphere is selected from the group consisting of vacuum, inert gas, reducing gas, or a combination thereof.

In another preferred example, the degree of vacuum is 10 ⁻⁴ Pa˜10 ⁶ Pa.

In another preferred embodiment, the inert gas is selected from the group consisting of helium, argon, or a combination thereof.

In another preferred embodiment, the reducing gas is selected from hydrogen, ammonia, or a combination thereof.

In another preferred example, the non-oxidizing atmosphere is a reducing gas under vacuum, preferably, the reducing gas is hydrogen.

In another preferred example, the reaction furnace is a vacuum carbon tube furnace.

In another preferred embodiment, the exfoliation treatment is selected from the group consisting of ultrasonic treatment, ball milling treatment, vibration, or a combination thereof.

In another preferred example, the medium for the exfoliation treatment is selected from the group consisting of water and ethanol.

In another preferred example, the time for the exfoliation treatment is 1-100 minutes, preferably 1-50 minutes, more preferably 1-20 minutes.

In another preferred example, the following step is further included before the exfoliation treatment: passing the high-temperature-treated surface-coated diamond D obtained in step (2) through 30-300 mesh sieves respectively.

In another preferred example, the mesh numbers of the mesh screen are: 30 mesh, 60 mesh, 80 mesh, 100 mesh, 150 mesh, and 300 mesh.

In another preferred example, the high temperature treatment and the peeling treatment are performed in cycles until the thickness of the second coating layer C2 reaches the target thickness c2'.

In another preferred example, the number of cycles of the cycle is 1 to 50 times

In another preferred example, the exfoliation treatment is performed before the high temperature treatment.

In another preferred example, after being treated by the method, the thickness reduction (c2'/c2) of the surface coating is 1-95%, preferably 10-70%, more preferably 10-50% .

In the second aspect of the present invention, there is provided a product prepared using the method described in the first aspect of the present invention, the product includes diamond and a surface coating C' bonded to the diamond surface, wherein the surface coating C 'comprising a first coating C1' and a second coating C2'; the first coating C1' is located between the diamond and the second coating C2';

The first coating C1' is a carbide layer selected from the group consisting of tungsten carbide, chromium carbide, molybdenum carbide, titanium carbide, or a combination thereof;

The second coating C2' is a carbide element layer or an alloy layer thereof, selected from the group consisting of tungsten, chromium, molybdenum, titanium, or a combination thereof;

The thickness of the first coating C1' is c1', the thickness of the second coating C2' is c2', and the thickness of the surface coating C' is c'.

In another preferred example, the diamond and the first coating C1' are combined by chemical bonding.

In another preferred example, the surface coating C' completely covers the diamond.

In another preferred example, the shape of the diamond is powder, block, sheet or film.

In another preferred embodiment, the diamond is natural or produced through high temperature, high pressure or chemical vapor deposition.

In another preferred example, the particle size of the diamond is 10-1000 μm, preferably 100-500 μm, more preferably 100-300 μm.

In another preferred example, c2' is 0 to 10000 nm.

In another preferred example, c2' is preferably 0-1000 nm, more preferably 0-10 nm.

In another preferred example, c' is 10-10000 nm, preferably 10-300 nm, more preferably 10-100 nm.

In another preferred example, the mesh size of the product is 30-300 mesh, preferably 50-100 mesh.

In another preferred example, after the product is composited with metal aluminum, the thermal conductivity of the obtained composite material is 420-460 W/m·K.

In a third aspect of the present invention there is provided an article comprising or made from the product of the second aspect of the present invention.

In the fourth aspect of the present invention, a use of the product described in the second aspect of the present invention is provided, the product is used for preparing mechanical products, composite materials, and/or electronic components.

In another preferred example, the mechanical products include: knives, grinding tools, files, grinding wheels, saw blades, drill bits and the like.

In another preferred example, the composite material includes: a heat dissipation substrate, a heat dissipation sheet, and the like.

It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described in the following (such as embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, we will not repeat them here.

Description of drawings

Fig. 1 is the diamond treatment process schematic diagram of surface coating of the present invention, and wherein, A is the diamond-carbide-metal coating composite surface topography schematic diagram; B is the composite surface coating rupture topography schematic diagram after the method is processed; C is The three-dimensional schematic diagram of the chapped overall structure of the complex.

Fig. 2 is the SEM image of the product obtained in Examples 1 and 2 of the present invention, wherein A and B are respectively complex D 300 ×, 10000 × magnification scanning electron micrographs; ×, 13000× magnification scanning electron microscope photo.

detailed description

After long-term and in-depth research, the inventor unexpectedly found that the thickness of the diamond surface coating can be effectively controlled by oxidizing the diamond on the surface of the coating at high temperature and then peeling it off, thereby achieving the effect of simplifying the process and reducing the cost. Based on the above findings, the inventors have accomplished the present invention.

the term

As used herein, the terms "coated diamond of the present invention", "coated diamond", "diamond-carbide-metal-coated composite" and "composite" are used interchangeably and refer to diamonds and coated diamonds. , wherein, the surface coating comprises a carbide layer and a carbide element layer or its alloy layer; the carbide layer is bonded to the diamond surface; the carbide element layer or its alloy layer is bonded to the carbide layer .

method

The method for preparing the diamond with controlled surface coating thickness of the present invention comprises the following steps:

(1) provide the diamond D of a surface coating, wherein, the diamond D of the surface coating comprises diamond and is bonded to the surface coating C of the described diamond surface; The surface coating C comprises the first coating C1 and the second coating C2; The first coating C1 is located between the diamond and the second coating C2;

The first coating layer C1 is a carbide layer selected from the group consisting of tungsten carbide, chromium carbide, molybdenum carbide, titanium carbide, or combinations thereof;

The second coating C2 is a carbide element layer or an alloy layer thereof, selected from the group consisting of tungsten, chromium, molybdenum, titanium, or a combination thereof;

The thickness of the first coating layer C1 is c1, and the thickness of the second coating layer C2 is c2;

(2) Carrying out high-temperature treatment to the diamond D of the surface coating, so that cracks appear in the second coating C2;

(3) Carrying out the diamond of the described surface coating of step (2) high-temperature treatment, falling off the second coating C2 to the target thickness c2', and obtaining a diamond D' with a reduced thickness of the surface coating, wherein 0≤ c2'<c2.

Specifically, the high-temperature treatment includes the following steps: placing the surface-coated diamond D in a reaction furnace with a treatment temperature of 200-1500° C. and a non-oxidizing atmosphere.

In a preferred example, the treatment temperature is preferably 300-1000°C, more preferably 650-850°C.

In a preferred example, after the diamond D coated on the surface is put into the reaction furnace at room temperature, the reaction furnace is heated to the processing temperature.

In a preferred example, the heating rate is 5-100°C/min, preferably 5-50°C/min, more preferably 5-20°C/min.

In a preferred example, the diamond D on the surface coating is kept at the treatment temperature.

In a preferred example, the holding time is 1-200 minutes, preferably 1-120 minutes, more preferably 5-120 minutes.

In a preferred example, the surface-coated diamond D is cooled after heat preservation treatment.

In a preferred example, the cooling rate is 5-100°C/min, preferably 5-50°C/min, more preferably 5-20°C/min.

In a preferred example, the reaction furnace cools down naturally after reaching the holding time.

In a preferred example, the surface coating C completely covers the diamond.

Typically, the non-oxidizing atmosphere includes (but is not limited to): vacuum, inert gas, reducing gas, or a combination thereof.

In a preferred example, the degree of vacuum is 10 ⁻⁴ Pa˜10 ⁶ Pa.

Typically, the inert gas includes (but is not limited to): helium, argon, or a combination thereof.

Typically, the reducing gas includes (but is not limited to): hydrogen, ammonia, or a combination thereof.

In a preferred example, the non-oxidizing atmosphere is a reducing gas under vacuum, preferably, the reducing gas is hydrogen.

In a preferred example, the reaction furnace is a vacuum carbon tube furnace.

Specifically, the exfoliation treatment includes (but is not limited to): ultrasonic treatment, ball milling treatment, vibration, or a combination thereof.

Typically, the medium for the exfoliation treatment includes (but is not limited to): water and ethanol.

In a preferred example, the time for the exfoliation treatment is 1-100 minutes, preferably 1-50 minutes, more preferably 1-20 minutes.

In a preferred example, the following step is further included before the exfoliation treatment: passing the high-temperature-treated surface-coated diamond D obtained in step (2) through 30-300 mesh sieves for treatment.

In a preferred example, the mesh numbers of the mesh screen are: 30 mesh, 60 mesh, 80 mesh, 100 mesh, 150 mesh, and 300 mesh.

Typically, the high temperature treatment and the peeling treatment are performed in cycles until the thickness of the second coating layer C2 reaches the target thickness c2'.

In a preferred example, the number of cycles of the cycle is 1 to 50 times

In a preferred example, the exfoliation treatment is performed before the high temperature treatment.

In a preferred example, after being treated by the method, the thickness reduction (c2'/c2) of the surface coating is 1-95%, preferably 10-70%, more preferably 10-50%.

Now take the diamond powder surface chromium plating and its compound layer as an example to illustrate the diamond surface coating thickness control process of the present invention. First, the coated diamond powder is ultrasonically or ball milled, so that the coating on the diamond surface is subjected to various external forces to form certain micro-cracks or micro-damages. Then, at a certain heating rate, the diamond powder is heated to a certain temperature for treatment, and kept for a period of time, and the diamond powder is treated at a certain cooling rate. Since the thermal expansion coefficient of the diamond and the diamond surface coating is different, at different temperatures , the microcracks on the coating on the diamond surface further expand, and then produce larger cracks. Finally, after the powder is taken out and further ultrasonicated or under the action of various forces, the second coating on the surface of the diamond powder will partly or completely fall off from the surface of the diamond powder, thereby controlling the thickness of the coating on the surface of the diamond powder.

The method of the present invention is basically irrelevant to the process control factors in the coating process of the surface of the diamond powder, and usually only related to the difference in thermal expansion coefficient between different layers in the coating and the properties of each layer.

The thickness of the diamond surface coating of the present invention is controlled. This new coating thickness control process greatly simplifies the time and cost spent on improving various process parameters in the diamond surface coating process, and has good application prospects in many aspects such as machinery, materials, and electronics.

product

The product of the present invention includes diamond and a surface coating C' bonded to the surface of the diamond, wherein the surface coating C' includes a first coating C1' and a second coating C2'; the first coating C1' is located at the between the diamond and the second coating C2';

The first coating C1' is a carbide layer selected from the group consisting of tungsten carbide, chromium carbide, molybdenum carbide, titanium carbide, or a combination thereof;

The second coating C2' is a carbide element layer or an alloy layer thereof, selected from the group consisting of tungsten, chromium, molybdenum, titanium, or a combination thereof;

The thickness of the first coating C1' is c1', the thickness of the second coating C2' is c2', and the thickness of the surface coating C' is c'.

In a preferred example, the diamond and the first coating C1' are combined by chemical bonding.

In a preferred example, the surface coating C' completely covers the diamond.

The surface coating of the product described in the present invention is easily affected by external temperature changes, ultrasonic or ball milling and other external forces to cause surface cracks and peeling off, thereby changing the thickness of the coating.

In a preferred example, the shape of the diamond is powder, block, sheet or film.

In a preferred example, the diamond is natural or produced through high temperature, high pressure or chemical vapor deposition.

In a preferred example, the particle size of the diamond is 10-1000 μm, preferably 100-500 μm, more preferably 100-400 μm.

In the product of the present invention, c2' is 0-10000nm.

In a preferred example, c2' is preferably 0-1000 nm, more preferably 0-10 nm.

In a preferred example, c' is 10-10000 nm, preferably 10-300 nm, more preferably 10-100 nm.

In a preferred example, the mesh of the product is 30-300 mesh, preferably 50-100 mesh.

After the product described in the invention is combined with metal aluminum, the thermal conductivity of the obtained composite material is 420-460 W/m·K.

Products and uses

The invention provides an article comprising or made from the product of the invention.

The product of the invention is used for preparing mechanical products, composite materials and electronic components.

Typically, the mechanical products include (but are not limited to): knives, grinding tools, files, grinding wheels, saw blades, drill bits and the like.

Typically, the composite material includes (but not limited to): a heat dissipation substrate, a heat dissipation sheet, and the like.

Compared with the prior art, the present invention has the following main advantages:

(1) using the inventive method can quickly and effectively control the thickness of the surface coating;

(2) Using the method of the present invention can greatly simplify the preparation process and reduce the preparation cost;

(3) use the inventive method processing equipment to be simple;

(4) the surface coating thickness of the prepared diamond using the inventive method is even;

The above-mentioned features mentioned in the present invention, or the features mentioned in the embodiments can be combined arbitrarily. All the features disclosed in the specification of this case can be used in combination with any combination, and each feature disclosed in the specification can be replaced by any alternative feature that provides the same, equivalent or similar purpose. Therefore, unless otherwise specified, the disclosed features are only general examples of equivalent or similar features.

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. For the experimental methods without specific conditions indicated in the following examples, usually follow the conventional conditions or the conditions suggested by the manufacturer. Percentages and parts are by weight unless otherwise indicated.

Unless otherwise defined, all professional and scientific terms used herein have the same meanings as commonly understood by those skilled in the art. In addition, any methods and materials similar or equivalent to those described can be applied to the method of the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only.

Example 1

Preparation of diamond composite D with chrome-plated layer on the surface

Mix 10g of diamond particles with an average particle size of about 100 μm with high-purity chromium powder and a small amount of polyethylene glycol (molecular weight: 2000) to make a mixture. Calculated by the total weight of the mixture, chromium powder accounts for 10 wt%, and polyethylene glycol accounts for 10% by weight. 5wt%. Put the mixture in a blender and stir to mix evenly to prepare a slurry. Put it into a vacuum carbon tube furnace, evacuate to a vacuum of about 10 ^-2 Pa, then pass in hydrogen, the gas pressure is 1Pa–120kPa, and the heating rate is 10°C/min. Cool to room temperature.

Take out the high-temperature treated mixture, pass through 30 mesh, 60 mesh, 80 mesh, 100 mesh, 150 mesh, and 300 mesh respectively, and then ultrasonically wash the obtained diamond particles to remove impurities, remove excess chromium powder, and obtain diamond-chromium carbide - Chromium-coated complex D, the weight of the weighed powder is 10.546g.

Example 2

Preparation of diamond composite D' with chrome-plated layer on the surface

Put 10.546g of 100-mesh chrome-plated diamonds prepared in Example 1 into the vacuum carbon tube furnace again, evacuate to a vacuum degree of about ^10-2 Pa, and then inject hydrogen gas with a pressure of 1Pa-120kPa. The heating rate is 10°C/min and the temperature is raised to 750°C, kept for 60 minutes, and then cooled to room temperature with the furnace.

Take out the high-temperature treated samples, pass through 30 mesh, 60 mesh, 80 mesh, 100 mesh, 150 mesh, and 300 mesh sieves respectively, and then ultrasonically wash to remove impurities and remove the falling substances on the surface of the diamond powder, and then the diamond surface coating can be obtained. Thin diamond composite D', weighing powder mass is 10.361g.

result

The surface morphology of the obtained product was detected.

After 1 high-temperature treatment and peeling treatment, the quality of the diamond on the chrome-plated layer on the surface is reduced from 10.546g to 10.361g, which shows that after the method of the present invention is processed, the particle size of the diamond is reduced, that is, the thickness of the diamond surface coating is reduced. Thin.

As can be seen from Fig. 2, after being processed by the method of the present invention, there are some microcracks in the surface coating that does not come off, and the existence of these microcracks provides a force site for its combination with other metals, which is conducive to improving its connection with other metals. The bond strength of the metal.

In addition, the above-mentioned microcracks can also be removed according to actual needs through the cleaning treatment steps mentioned in the invention patent application titled "A Method for Preparing Diamond with a Reduced Surface Coating Thickness" filed on the same day as the present invention.

Example 3

The composite material 1 prepared by the composite body D obtained in embodiment 1 and metal aluminum

The composite D obtained in Example 1 was mixed with metal aluminum powder, and vacuum hot-pressed at 650° C. for 60 minutes to obtain composite material 1 .

result

The thermal conductivity test of the obtained composite material 1 was carried out, and the thermal conductivity of the composite material 1 was tested to be 396 W/m·K.

Example 4

Composite material 2 prepared by embodiment 2 gained composite body D ' and metal aluminum

The composite D' obtained in Example 2 was mixed with metal aluminum powder, and vacuum hot-pressed at 650°C for 60 minutes to obtain composite material 2.

result

The thermal conductivity of composite material 2 was tested to be 435W/m·K.

Comparing Examples 3 and 4, it can be seen that after being treated by the method of the present invention, the thermal conductivity of the composite material is significantly improved, and the improvement rate is as high as 9.8%.

All documents mentioned in this application are incorporated by reference in this application as if each were individually incorporated by reference. In addition, it should be understood that after reading the above teaching content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims (10)

1. a method for preparing the controlled diamond of surface coating thickness, is characterized in that, comprises the steps: (1) provide the diamond D of a surface coating, wherein, the diamond D of the surface coating comprises diamond and is bonded to the surface coating C of the described diamond surface; The surface coating C comprises the first coating C1 and the second coating C2; The first coating C1 is located between the diamond and the second coating C2; The first coating layer C1 is a carbide layer selected from the group consisting of tungsten carbide, chromium carbide, molybdenum carbide, titanium carbide, or combinations thereof; The second coating C2 is a carbide element layer or an alloy layer thereof, selected from the group consisting of tungsten, chromium, molybdenum, titanium, or a combination thereof; The thickness of the first coating layer C1 is c1, and the thickness of the second coating layer C2 is c2; (2) Carrying out high-temperature treatment to the diamond D of the surface coating, so that cracks appear in the second coating C2; (3) Carrying out the diamond of the described surface coating of step (2) high-temperature treatment, falling off the second coating C2 to the target thickness c2', and obtaining a diamond D' with a reduced thickness of the surface coating, wherein 0≤ c2'<c2. 2. The method according to claim 1, wherein the high temperature treatment comprises the following steps: placing the diamond D of the surface coating in a reaction where the treatment temperature is 200-1500°C and the treatment atmosphere is a non-oxidizing atmosphere in the furnace. 3. The method of claim 2, wherein the non-oxidizing atmosphere is selected from the group consisting of vacuum, inert gas, reducing gas, or combinations thereof. 4. The method of claim 1, wherein the exfoliation treatment is selected from the group consisting of ultrasonic treatment, ball milling treatment, vibration, or a combination thereof. 5. The method according to claim 1, characterized in that, the high temperature treatment and the peeling treatment are carried out in a cycle until the thickness of the second coating C2 reaches the target thickness c2'. 6. A product prepared by the method of claim 1, wherein the product comprises diamond and a surface coating C' bonded to the diamond surface, wherein the surface coating C' comprises a first coating C1 'and the second coating C2'; the first coating C1' is located between the diamond and the second coating C2'; The first coating C1' is a carbide layer selected from the group consisting of tungsten carbide, chromium carbide, molybdenum carbide, titanium carbide, or a combination thereof; The second coating C2' is a carbide element layer or an alloy layer thereof, selected from the group consisting of tungsten, chromium, molybdenum, titanium, or a combination thereof; The thickness of the first coating C1' is c1', the thickness of the second coating C2' is c2', and the thickness of the surface coating C' is c'. 7. The product according to claim 6, characterized in that c2' is 0-10000nm. 8. The product according to claim 6, characterized in that, after the product is composited with metal aluminum, the thermal conductivity of the composite material obtained is 420-460 W/m·K. 9. An article comprising or made from the product of claim 6. 10. The use of the product according to claim 6, characterized in that the product is used for the preparation of mechanical products, composite materials, and/or electronic components.