CN111233515B

CN111233515B - Method for preparing nano-graphite coating on surface of graphite product

Info

Publication number: CN111233515B
Application number: CN202010197141.2A
Authority: CN
Inventors: 杨振远; 白俊鹏
Original assignee: Beijing Jinglong Special Carbon Technology Co ltd
Current assignee: Beijing Jinglong Special Carbon Technology Co ltd
Priority date: 2020-03-19
Filing date: 2020-03-19
Publication date: 2022-04-22
Anticipated expiration: 2040-03-19
Also published as: CN111233515A

Abstract

The invention discloses a method for preparing a nano-graphite coating on the surface of a graphite product, belonging to the field of new materials. The coating is obtained by surface microstructure adjustment, surface oxidation and high-temperature sintering. The method is suitable for protecting volatile carbon materials, inhibiting the phenomenon of powder falling at normal temperature and inhibiting the volatilization of materials at high temperature. The carbon material coated with the coating is particularly suitable for growth protection of high-purity single crystal materials.

Description

Method for preparing nano-graphite coating on surface of graphite product

Technical Field

The invention belongs to the field of new materials, and particularly relates to a method for preparing a nano graphite coating on the surface of a graphite product.

Background

The production and scientific research of semiconductor materials, devices, integrated circuits has become an important component of the electronics industry. Parts, integrated circuits and the like made of semiconductor materials are important basic products in the electronic industry, and have great application in the fields of daily life, military and aerospace.

The growth of semiconductor materials requires a high-purity high-temperature furnace as a growth container, so that the high purity of gas molecules in the container is ensured in the high-temperature process. The currently available thermal coatings are mainly two types of silicon carbide coatings and thermally deposited graphite coatings. However, silicon carbide coatings cannot withstand long-term high temperature processes, particularly those above 2000 degrees, and also volatilize themselves. The thickness of the thermal deposition graphite coating is very large, the coating time is long, the cost is high, and peeling and falling are easy to occur.

Therefore, there is a need for a coating preparation method that combines two inexpensive and convenient coating preparation methods, while also being applicable over a very large temperature range.

Disclosure of Invention

The invention aims to provide a method for preparing a nano graphite coating on the surface of a graphite product, which solves the problem of pollution caused by easy volatilization of a high-temperature protective coating in the prior art.

The invention also aims to provide a method for preparing a nano-graphite coating on the surface of a graphite product, which adopts dynamic oxidation to activate the surface of the graphite product, and the dynamically flowing strong acid oxidation solution enables the top end of a graphene layer on the surface of the graphite product to swell, and the contact area between graphene oxide on the surface of the graphite product and sprayed graphene oxide is increased along with the orientation of the dynamically flowing liquid flow, so that the stability of the coating is increased.

Another object of the present invention is to provide a method for preparing a nano-graphite coating on a surface of a graphite product, which uses dynamic oxidation to activate the surface of the graphite product to generate a large number of binding sites to bind with the sprayed graphene oxide, thereby improving the stability of the coating.

Another object of the present invention is to provide a method for preparing a nano-graphite coating on the surface of a graphite product, which uses dynamic oxidation to activate the surface of the graphite product, so as to generate a large number of binding sites to be bound with the sprayed graphene oxide, wherein the binding sites form defects, and the defects are combined with high-temperature carbonization and sintering, and the coating and the surface of the graphite product form atomic-level binding along with defect repair.

The invention also aims to provide a method for preparing the nano-graphite coating on the surface of the graphite product, which adopts the graphene oxide solution with the size dispersion coefficient of more than 0.6 for spraying, and small pieces of graphene can penetrate into gaps of the interface of the graphite product to play the roles of filling and riveting, thereby further enhancing the stability of the interface.

The invention adopts the following technical scheme: a method for preparing a nano-graphite coating on the surface of a graphite product, which comprises the following steps:

(1) carrying out dynamic oxidation treatment on the surface of a graphite product, specifically, immersing the surface of the graphite product in a dynamically flowing strong acid oxidation solution; the strong acid oxidation solution is a sulfuric acid solution of A and B, wherein B is an oxide, A is a high oxide or peroxide of B, the volume mass ratio of sulfuric acid to A is between 60mL:1g and 0.1g, the mass ratio of A to B is between 1:2 and 1:5, and the oxidation time is 10min to 30 min.

A and B comprise: potassium permanganate and manganese dioxide; potassium ferrate and iron dioxide; hydrogen peroxide and water.

(2) And cleaning with deionized water, and spraying a graphene oxide solution on the surface to form a film, wherein the thickness of the film is less than 100 nm. The size of the graphene oxide in the graphene oxide solution is 10-100 u m, and the dispersion coefficient is more than 0.6.

(3) After being dried, the mixture is sintered for 1 hour at 150 ℃ and then is put into a high-temperature furnace for high-temperature carbonization.

Further, in the step 1, the strongly acidic oxidizing solution is a peroxide or a hyperoxide and a sulfuric acid solution of the corresponding oxide, wherein the peroxide or the hyperoxide can be hydrogen peroxide, potassium permanganate and potassium ferrate, the corresponding oxide is water, manganese dioxide and iron oxide, the volume mass ratio of the sulfuric acid to the hyperoxide is 60mL:1 g-0.1 g, the mass ratio of the peroxide to the hyperoxide is 2: 1-1: 5, and the oxidation time is 1min-30 min.

Further, in the step 2, the concentration of the graphene oxide solution is between 10ug and 1mg/mL, so as to realize the preparation of the graphene film with the nano-scale thickness.

Further, in step 3, high-temperature carbonization: heating to 1600 deg.C at 5 deg.C/min, maintaining at 1600 deg.C for 4 hr, and heating to 2600 deg.C at 20 deg.C/min.

The graphite product of the invention comprises a graphite substrate, a graphite boat and the like.

The invention has the beneficial effects that: the nano coating has tight binding force, can be coated without a coarse structure, has controllable coating thickness, small thickness of the nano coating and extremely low cost.

Drawings

FIG. 1 is a schematic diagram of coating preparation;

FIG. 2 is a coating for low density crystallite leakage;

FIG. 3 is a coating with high density crystallite leakage;

fig. 4 is a device for measuring the content of microcrystals in a unit area, wherein 1 is a sealing cover prepared by HOPG, 2 is a nano-thickness graphite film prepared by CVD, 4 is a graphite product, and 3 is a graphene coating on the surface of the graphite product.

Detailed Description

Example 1:

a method for preparing a nano-graphite coating on the surface of a graphite product, which comprises the following steps:

(1) 1g of potassium permanganate and 2g of manganese dioxide are dissolved in 60mL of concentrated sulfuric acid with the mass fraction of 98 percent to obtain a strongly acidic oxidizing solution.

Mixing large-size graphene oxide and small-size graphene oxide within the range of 10-100 um in proportion to prepare a graphene oxide solution, so that the distribution coefficient of the sizes is over 0.6.

(2) Taking a square groove with an inlet and an outlet, enabling the strong acid oxidation solution to circularly flow from the inlet to the outlet at a flow speed of 0.1m/s, immersing the surface of the graphite product in the flowing strong acid oxidation solution, and soaking for 30 min.

(3) And (3) cleaning with deionized water, and spraying 10ug/mL of the graphene oxide solution prepared in the step (1) on the surface to form a film, wherein the thickness of the film is less than 100 nm.

(4) After being dried, the mixture is sintered for 1 hour at 150 ℃ and then is put into a high-temperature furnace for high-temperature carbonization; the high-temperature carbonization temperature process is as follows: heating to 1600 deg.C at 5 deg.C/min, maintaining at 1600 deg.C for 4 hr, and heating to 2600 deg.C at 20 deg.C/min.

As shown in fig. 1, the graphite tip in the vertical direction is locally oriented along the coating direction due to dynamic oxidation and oxidation expansion, so that the coating can have excellent conformability and adhesion effect with the graphite on the surface of the product; meanwhile, the small-size graphene is beneficial to reducing the viscosity of the solution, so that the solution can penetrate into gaps of graphite crystal grains, and the contact area and the adhesive force are increased.

Comparative examples 1 to 1

The difference from example 1 is that the surface of the graphite product is oxidized in step 2 by plasma treatment.

Comparative examples 1 to 2

The difference from example 1 is that step 2 is carried out by oxidation treatment using a strongly acidic oxidizing solution in a static state.

Comparative examples 1 to 3

The difference from example 1 is that step 3 was performed by spraying a graphene oxide solution of a relatively uniform size (distribution coefficient 0.3).

	Number of times of sintering	Crystallite content per unit area
			Example 1	60	10 (fig. 2)
Comparative examples 1 to 1	3	300
			Comparative examples 1 to 2	40	24
Comparative examples 1 to 3	32	41

The sintering-resistant frequency test method comprises the following steps: and (3) placing the coated product in an environment with the temperature of 2600 ℃, sintering for 2 hours, and cooling and then sintering for the next time. The sintering resistant times are the limit times until the coating structure is damaged or the volatile microcrystal data exceeds the standard. The structural failure of the coating means: the fracture length is greater than 0.1 mm. The standard exceeding of the volatile microcrystal data means that: the number of volatile microcrystals is more than 100 per square centimeter.

The method for testing the content of the microcrystals in the unit area comprises the following steps: laying a CVD method prepared nano-thickness graphite film on the surface (one side containing a graphene coating) of a sample to be detected, preparing a sealing cover by using HOPG, and pressing the CVD method prepared nano-thickness graphite film on the periphery; as shown in fig. 4. Sintering at 2600 deg.C for 2 hr. And detecting the number of microcrystals in unit area on the lower surface of the graphite film with the nanometer thickness prepared by the CVD method by a calibration method of a scanning electron microscope.

Example 2:

(1) 1g of hydrogen peroxide and 5g of water are dissolved in 600mL of concentrated sulfuric acid with the mass fraction of 98 percent to obtain a strongly acidic oxidizing solution.

(2) Taking a square groove with an inlet and an outlet, enabling the strong acid oxidation solution to circularly flow from the inlet to the outlet at a flow speed of 0.1m/s, immersing the surface of the graphite product in the flowing strong acid oxidation solution, and soaking for 10 min.

(3) And (3) cleaning with deionized water, and spraying 1mg/mL of the graphene oxide solution prepared in the step (1) on the surface to form a film, wherein the thickness of the film is less than 100 nm.

Comparative example 2-1

The difference from example 2 is that the surface of the graphite product is oxidized in step 2 by using a plasma treatment method.

Comparative examples 2 to 2

The difference from example 2 is that step 2 is carried out by oxidation treatment using a strongly acidic oxidizing solution in a static state.

Comparative examples 2 to 3

The difference from example 2 is that step 3 was performed using a more uniform size (distribution coefficient 0.2) graphene oxide solution.

	Number of times of sintering	Crystallite content per unit area
			Example 2	46	17
Comparative example 2-1	2	1000 (fig. 3)
			Comparative examples 2 to 2	27	43
Comparative examples 2 to 3	24	57

Example 3:

(1) 1g of potassium ferrate and 4g of ferric oxide are dissolved in 100mL of concentrated sulfuric acid with the mass fraction of 98 percent to obtain a strongly acidic oxidizing solution.

(2) Taking a square groove with an inlet and an outlet, enabling the strong acid oxidation solution to circularly flow from the inlet to the outlet at a flow speed of 0.1m/s, immersing the surface of the graphite product in the flowing strong acid oxidation solution, and soaking for 20 min.

(3) And (3) cleaning with deionized water, and spraying 0.5mg/mL of the graphene oxide solution prepared in the step (1) on the surface to form a film, wherein the thickness of the film is less than 100 nm.

The obtained product has a sintering resistant frequency of 57 and a crystallite content per unit area of 21.

Example 4:

(1) 1g of potassium permanganate and 2g of manganese dioxide are dissolved in 80mL of concentrated sulfuric acid with the mass fraction of 98 percent to obtain a strongly acidic oxidizing solution.

(4) After being dried, the mixture is sintered at 150 ℃ and then is put into a high-temperature furnace for high-temperature carbonization; the high-temperature carbonization temperature process is as follows: heating to 1600 deg.C at 5 deg.C/min, maintaining at 1600 deg.C for 4 hr, and heating to 2600 deg.C at 20 deg.C/min.

The obtained product has the sintering resistant times of 61 and the content of microcrystals in unit area of 9.

Claims

1. A method for preparing a nano graphite coating on the surface of a graphite product is characterized by comprising the following steps:

(1) carrying out dynamic oxidation treatment on the surface of a graphite product, specifically, immersing the surface of the graphite product in a dynamically flowing strong acid oxidation solution; the strong acid oxidation solution is a sulfuric acid solution of A and B, wherein B is an oxide, A is a high oxide or peroxide of B, the volume mass ratio of sulfuric acid to A is between 60mL:1g and 0.1g, the mass ratio of A to B is between 1:2 and 1:5, and the oxidation time is 10min to 30 min; a and B are selected from one of the following combinations:

a is potassium permanganate and B is manganese dioxide;

the A is potassium ferrate, and the B is iron dioxide;

a is hydrogen peroxide and B is water;

(2) cleaning with deionized water, and spraying a graphene oxide solution on the surface to form a film, wherein the concentration of the graphene oxide solution is between 10ug/mL and 1 mg/mL; the thickness of the film is less than 100 nm; the size of the graphene oxide in the graphene oxide solution is 10-100 um, and the dispersion coefficient is more than 0.6;

(3) after being dried, the mixture is sintered for 1 hour at 150 ℃ and then is put into a high-temperature furnace for high-temperature carbonization; the high-temperature carbonization procedure is as follows: heating to 1600 deg.C at 5 deg.C/min, maintaining at 1600 deg.C for 4 hr, and heating to 2600 deg.C at 20 deg.C/min.

2. The method for preparing the nano-graphite coating on the surface of the graphite product according to claim 1, wherein the graphite product is a graphite substrate.